Evolution of antennules of cytheroidean ostracods (Crustacea)

Phylogenetic analysis and fossil records indicate that antennules with whip-like setae are the most plesiomorphic state in cytheroidean ostracods and that antennulae with claw-like setae are derived from antennulae with whip-like setae. Character distributions on the 18S rDNA molecular phylogenetic tree suggest that two phenotypic features of cytheroidean antennules (W/L ratio and claw-like/whip-like setae) have morphological plasticity. These features have evolved as an ethological adaptation rather than due to phylogenetic constraints such as the evolution of shell outline in cytheroideans. However, the species of the Leptocytheridae-Trachyleberididae clade generally have stout, robust antennules, indicating a phylogenetic constraint. The character state of setae (claw/whip) in cytheroidean ostracods is reflected more through their ethology than the W/L ratio of the antennules. On the basis of the present analysis and the fossil record, diversification in the morphology of the antennules seems to have occurred during the early Mesozoic.

Life-stage-dependent sensitivity of the cyclopoid copepod Mesocyclops leuckarti to triphenyltin

The effects of triphenyltin (TPT) on non-target aquatic groups like copepods have not yet been studied in detail. Recently, Mesocyclops leuckarti was suggested as a representative species for freshwater cyclopoid copepods to study the effects of plant protection products. We conducted 96h acute toxicity tests in the laboratory to study the effects of TPT on the different life stages of M. leuckarti. We used the recently proposed General Unified Threshold model of Survival (GUTS) to mechanistically describe the underlying toxicokinetic and toxicodynamic process for the nauplii, copepodites and adults (males and females) of M. leuckarti. Experimental results showed that nauplii were significantly more sensitive to TPT compared to the other stages. Also, the 96h LC50 values were much lower than the 48h LC50 values, suggesting that standard acute toxicity test durations for aquatic invertebrates may underestimate toxic effects with respect to compounds like TPT which have a slow mechanism of action. The GUTS analysis, which mechanistically described the toxicity of TPT to the different life stages of M. leuckarti, suggested that the differences in sensitivity were a consequence of a lower threshold of effects in the nauplii compared to a higher threshold in the later stages. This study shows the potential of using the GUTS to understand how toxic compounds interact with different life-stages. Further experiments to provide a more detailed understanding of toxicokinetics of TPT in copepods could be useful.

The effects of mercury on the dynamics of the peracarida community in a temperate coastal lagoon (Ria de Aveiro, Portugal)

This study focuses on the impact of mercury on the dynamics and bioaccumulation patterns of suprabenthic peracarida community along a mercury gradient. Suprabenthic peracarida was negatively affected in terms of biomass, diversity and productivity. Mysids including Mesopodopsis slabberi dominated the community, presenting a regular distribution along the Hg gradient, so are considered tolerant species to mercury. Then, isopods, the second most abundant group, dominated in the most contaminated areas being considered also a tolerant group. Contrarily, amphipods were negatively correlated with higher Hg concentrations, dominating in the intermediate areas, thus are considered more sensitive species. In addition, isopods and amphipods were the taxa with higher mercury body burden, followed by mysids. This paper highlights the importance of suprabenthic peracarida as a vehicle of mercury transference through the estuarine trophic web since it is a main link between benthic and pelagic levels and an essential food resource for numerous fish species.

Influence of the bioaccessible fraction of polycyclic aromatic hydrocarbons on the ecotoxicity of historically contaminated soils

Sequential supercritical fluid extraction together with a two-site desorption model were employed to estimate the bioaccessible fraction of polycyclic aromatic hydrocarbons (PAHs) in four historically contaminated soils. The ecotoxicity of the soils was assayed by four different contact tests. The same soils were exposed to exhaustive extraction and the extracts were returned to the soils to ensure total 100% bioaccessibility of the pollutants. Then the soils were assayed again. Statistical evaluation revealed that the predicted bioaccessible PAHs generally correlated with the ecotoxicity responses of the tests. The estimated bioaccessible fractions varied from 10 to 98%. This value increased for PAHs with higher lipophilicity and showed no correlation with the organic carbon content in the soils. The ecotoxicity tests in the study indicated different sensitivity toward PAHs and the tests employing Heterocypris incongruens and Eisenia fetida were found to be more suitable than Lemna minor and Vibrio fischeri. Mortality and growth inhibition of ostracods correlated with all the types of PAHs and earthworm growth inhibition and mortality were preferentially sensitive to PAHs with only 3-4 aromatic rings. Determination of the biota-soil accumulation factors indicated that the earthworm growth inhibition corresponded to increased accumulation of PAHs in the earthworm tissue.

Effects of nano-sized zero-valent iron (nZVI) on DDT degradation in soil and its toxicity to collembola and ostracods

Nano-sized zero valent iron (nZVI) has been studied for in situ remediation of contaminated soil and ground water. However, little is known about its effects on organisms in soil and aquatic ecosystems. In this study, the effect of nZVI on degradation of DDT and its ecotoxicological effects on collembola (Folsomia candida) and ostracods (Heterocypris incongruens) were investigated. Two soils were used in suspension incubation experiments lasting for 7 and 30 d; a spiked (20 mg DDT kg(-1)) sandy soil and an aged (>50 years) DDT-polluted soil (24 mg DDT kg(-1)). These were incubated with 1 or 10 g nZVI kg(-1), and residual toxicity in soil and the aqueous phase tested using ecotoxicological tests with collembola or ostracods. Generally, addition of either concentration of nZVI to soil led to about 50% degradation of DDT in spiked soil at the end of 7 and 30 d incubation, while the degradation of DDT was less in aged DDT-polluted soil (24%). Severe negative effects of nZVI were observed on both test organisms after 7 d incubation, but prolonged incubation led to oxidation of nZVI which reduced its toxic effects on the tested organisms. On the other hand, DDT had significant negative effects on collembolan reproduction and ostracod development. We conclude that 1 g nZVI kg(-1) was efficient for significant DDT degradation in spiked soil, while a higher concentration was necessary for treating aged pollutants in soil. The adverse effects of nZVI on tested organisms seem temporary and reduced after oxidation.

Effects of green macroalgal blooms on the meiofauna community structure in the Bay of Cádiz

The effect of macroalgal blooms on the abundance and community structure of intertidal sediment meiofauna was studied using an in situ enclosure experiments (Bay of Cádiz, Spain). Meiofaunal abundance (3500-41,000 ind 10 cm⁻²) was three to sevenfold higher in the presence of macroalgae. Nematoda were the dominant taxon both in Control (52-82%) and Macroalgae plots (92-96%), followed by Harpacticoida Copepoda and Ostracoda. Non-metric Multi-Dimensional Scaling (MDS) analysis clearly separated the meiofaunal community from Control and Macroalgae plots. Organic matter, organic carbon, total nitrogen, chlorophyll a and freeze-lysable inorganic nutrients were higher in Macroalgae plots, and were highly correlated with the horizontal MDS axis separating Control and Macroalgae meiofaunal communities. Meiofaunal abundance and taxonomic composition in the Bay of Cádiz seem to be bottom-up controlled either through a grazer system based on microphytobenthos in bare sediments or through a decomposer system in macroalgae affected sediments.

[Ecological characteristics and seasonal variation of macrobenthos near the Ningjin coastal water of Shandong, East China]

The coastal water off Ningjin is located at the eastern end of the Shandong Peninsula, the boundary of the Northern and Southern Yellow Sea. In this paper, the ecological characteristics and seasonal variation of macrobenthic community in this region were studied, based on the investigation data collected from the four cruises in January (winter), April (spring), July (summer), and October (autumn), 2007. A total of 243 macrobenthic species were identified, of which, 96 species were of Polychaeta, 77 were of Crustacea, 43 were of Mollusca, 13 were of Echinodermata, and the rest 14 species were of other benthic groups. The dominant species varied with seasons, but Paralacydonia paradoxa (Polychaeta) and Amphioplus japonicus (Echinodermata) were dominant throughout the four seasons. The average biomass of the macrobenthos estimated from the four cruises was 9.5 g x m(-2), with the highest biomass during the spring cruise and the lowest one during the winter cruise. The average abundance estimated from the four cruises was 219.6 ind x m(-2), with the highest abundance during the winter cruise and the lowest one during the autumn cruise. The Shannon index (H) of the macrobenthos community varied from 2.82 to 3.23, the species richness index (D) varied from 2.28 to 2.75, and the species evenness index (J) varied from 0.82 to 0.86. The Bray-Curtis similarity cluster analysis and MDS ordination analyses indicated that there was a distinct distribution of macrobenthic communities from seashore to offshore, which was closely correlated with the spatial structure of bathymetry and the sediment type in the study region.

[Analysis of the source, potential biological toxicity of heavy metals in the surface sediments from shellfish culture mudflats of Rudong Country, Jiangsu Province]

Concentrations of six heavy metals were measured in the surface sediments from shellfish culture mudflats of Rudong Country, Jiangsu Province in 2010. The geo-accumulation index (Igeo) was employed to evaluate the pollution level of heavy metals and the results showed that the heavy metal contamination could be divided into three groups: no contamination (Igeo), as in the case of Cu, Cd, Hg; light to moderate contamination (0 < Igeo, < 1), as in the case of Pb, As; and moderate contamination (1 < Igeo, < 2), as in the case of Zn. The pollution level of heavy metals followed the order of Zn > As > Pb > Cd > Cu > Hg. The potential biological toxicity was analyzed using sediment quality guidelines (SQG), as the guideline values, Cd showed no potential biological toxicity, As showed occasional potential biological toxicity in all sampling stations, Cu, Pb, Zn, Hg showed potential biological toxicity in some sampling stations, whereas Zn was the only one showing frequent potential biological toxicity in some sampling stations. Sigma TUs revealed that only one of the sampling stations showed significant acute toxicity, whereas the others showed no acute toxicity. Analysis of heavy metal contamination source through principal component analysis (PCA) revealed that the contribution rates of the top two principal components were 37.56% and 33.71%, respectively, indicating that the two main sources of heavy metals were industrial waste water and pollution from transportation and shipping.

Evaluation of sampling sizes on the intertidal macroinfauna assessment in a subtropical mudflat of Hong Kong

In this study, two types of sediment cores with different diameters were used to collect sediment samples from an intertidal mudflat in Hong Kong to investigate the influence of sampling unit on the quantitative assessment of benthic macroinfaunal communities. Both univariate and multivariate analyses were employed to detect differences in sampling efficiencies by the two samplers through total abundance and biomass, species richness and diversity, community structure, relative abundance of major taxa of the infaunal community. The species-area curves were further compared to find out the influence of the sampling units. Results showed that the two sampling devices provided similar information on the estimates of species diversity, density and species composition of the benthos in main part of the mudflat where the sediment was fine and homogenous; but at the station which contained coarse sand and gravels, the significant differences were detected between the quantitative assessments of macrobenthic infauna by the two samplers. Most importantly, the species-area curves indicated that more and smaller samples were better in capturing more species than less large ones when comparing an equal sampling area. Therefore, the efficiency of the sampler largely depended on the sediment properties, and sampling devices must be chosen based on the physical conditions and desired levels of precision on the organisms of the sampling program.

Could the canopy structure of bryophytes serve as an indicator of microbial biodiversity? A test for testate amoebae and microcrustaceans from a subtropical cloud forest in Dominican Republic

The mechanisms that ultimately regulate the diversity of microbial eukaryotic communities in bryophyte ecosystems remain a contentious topic in microbial ecology. Although there is robust consensus that abiotic factors, such as water chemistry of the bryophyte and pH, explain a significant proportion of protist and microcrustacean diversity, there is no systematic assessment of the role of bryophyte habitat complexity on such prominent microbial groups. Water-holding capacity is correlated with bryophyte morphology and canopy structure. Similarly, canopy structure explains biodiversity dynamics of the macrobiota suggesting that canopy structure may also be a potential parameter for understanding microbial diversity. Canopy roughness of the dominant bryophyte species within the Bahoruco Cloud Forest, Cachote, Dominican Republic, concomitant with their associated diversity of testate amoebae and microcrustaceans was estimated to determine whether canopy structure could be added to the list of factors explaining microbial biodiversity in bryophytes. We hypothesized that smooth (with high moisture content) canopies will have higher species richness, density, and biomass of testate amoebae and higher richness and density of microcrustaceans than rough (desiccation-prone) canopies. For testate amoebae, we found 83 morphospecies with relative low abundances. Species richness and density differed among bryophytes with different bryophyte canopy structures and based on non-metric multidimensional scaling, canopy roughness explained 25% of the variation in species composition although not as predicted. Acroporium pungens (low roughness, LR) had the lowest species richness (2 ± 0.61 SD per gram dry weight bryophyte), and density (2.1 ± 0.61 SD individual per gram of dry weight bryophyte); whereas Thuidium urceolatum (high roughness) had the highest richness (24 ± 10.82 SD) and density (94 ± 64.30 SD). The fact that the bryophyte with the highest roughness had the highest levels of diversity for testate amoebae suggests that moisture levels at the level of the bryophyte canopy may not represent a biodiversity driver in a cloud forest with high relative humidity; however, high roughness could generate a dynamic and fluctuating moisture environment with concomitant alternating microbial communities. A total of 26 microcrustacean morphospecies were found across 11 bryophytes; however, no bryophyte canopy effect was detected on their richness and density. Microcrustacean mean density was low ranging from less than one individual per 50 cm2 of bryophyte in Leucobryum (LR) to a maximum of 6 ± 3.37 SD individuals/50 cm2 in Monoclea (LR). This lack of pattern suggests that possible explanatory variables may be related to larger scale processes than those examined in this study.

Effects of metal pyrithione antifoulants on freshwater macrophyte Lemna gibba G3 determined by image analysis

Copper pyrithione (CuPT(2)) and zinc pyrithione (ZnPT(2)) are two popular antifouling agents that prevent biofouling. Research into the environmental effects of metal pyrithiones has mainly focused on aquatic animal species such as fish and crustaceans, and little attention has been paid to primary producers. There have been few reports on residues in environmental matrices because of the high photolabile characteristics of the agents. Residue analyses and ecological effects of the metabolites and metal pyrithiones are not yet fully understood. This study was undertaken to assess the effects of CuPT(2), ZnPT(2), and six metabolites (PT(2): 2,2'-dithio-bispyridine N-oxide, PS(2): 2,2'-dithio-bispyridine, PSA: pyridine-2-sulfonic acid, HPT: 2-mercaptopyridine N-oxide, HPS: 2-mercaptopyridine, and PO: pyridine N-oxide) on a freshwater macrophyte. A 7-day static bioassay using axenic duckweed Lemna gibba G3 was performed under laboratory conditions. Toxic effects of test compounds were assessed by biomass reduction and morphological changes were determined in image analysis. Concentrations of ZnPT(2) and CuPT(2) and those of PT(2) and HPT in the medium were determined by derivatizing 2,2'-dithio-bispyridine mono-N-oxide with pyridine disulfide/ethylene diamine tetra-acetic acid reagent that was equimolar with pyrithione. The toxic intensity of the compounds was calculated from the measured concentrations after 7-day exposure. ZnPT(2), CuPT(2), PT(2), and HPT inhibited the growth of L. gibba with EC(50) ranging from 77 to 140 μg/l as calculated from the total frond number as the conventional index, whereas the other four metabolites had less effect even at 10 mg/l. The presence of the former four toxic derivatives resulted in abnormally shaped and unhealthily colored fronds, whose size was about 20% of the control fronds. EC(50), calculated from the healthy frond area determined in image analysis, ranged from 10 to 53 μg/l. Thus, image analysis as part of a duckweed bioassay can detect the toxic effects of pyrithione derivatives with 3-10 times higher sensitivity than the traditional index.

The reproductive system of Derocheilocaris typica (Crustacea, Mystacocarida)

Mystacocarids are dioecious. Their gonopores are on the medial side of the third thoracic limb. The male's paired testes lie in the thorax and abdomen. They develop from paired rows of six small follicles dorsally. In the mature animal they fill most of the abdomen. The spermatophores develop within the follicles from spermatogonia mixed with follicle cells, which support and nourish the spermatocytes and produce the seminal fluid. The short vas deferens runs along the bottom of the testes and then continues forward to the gonopore. The vas deferens has a small group of cells near the gonopore that becomes a closure mechanism. The female has reproductive cells and also support cells that provide nutrition and form the wall of the ovary and oviduct. The unpaired female ovary begins in the third thoracic segment. During maturation, the oocytes are pushed posteriorly. The enormous mature ovum extends into a caudal pocket of the ovary. Starting with its anterior end, this ovum is extruded into the short oviduct, which extends laterally and ventrally to the gonopore. During extrusion, the pocket is reabsorbed from behind. There are no accessory structures connected to the reproductive system, nor any external specializations on the third limb.

Developmental process of musculoskeletal integration in ostracod antenna

The functional morphology of arthropod appendages shows remarkable diversity. Plausible functional integrations, particularly between muscles and the exoskeleton, must be achieved in these diverse morphologies. This study provides an insight into the evolutionary pathway of diversified appendages from a functional point of view. The musculoskeletal structure and development of antennae in five species of Cypridocopina were compared. The muscle and skeletal systems are integrated in several ways: The integration in Propontocypris attenuata occurs during various stages of the molting growth, whereas that in Fabaeformiscandona breuili occurs during the myogenesis. These two types of developmental processes have notable similarities, despite their occurrence during different developmental phases. From the overview of the molecular phylogeny presented by earlier studies, it is suggested that the integrated musculoskeletal system has reappeared repeatedly in cypridoid lineages as an atavism. This study demonstrates how arthropod appendages evolve without losing the integrity of the functional whole.

Intersexuality in Crustacea: an environmental issue?

This paper aims to give a historical overview of current understanding about intersexuality in crustaceans, assesses gaps in our knowledge and asks whether it should be an environmental concern. The oldest known cases of intersexuality come from 70 million year old fossil crabs whilst the oldest published case of intersex crustacean stems from a 1730 Royal Society report of a gynandromorph lobster. Many crustacean species are sequential hermaphroditic or simultaneous hermaphrodites. Consequently, there has been confusion as to whether accounts of intersex in the literature are correct. Intersexuality is fairly common throughout the Crustacea and it has been suggested that intersex may arise through different mechanisms. For example, sexual gynandromorphism may arise through disruption in early embryonic development whereas intersexuality may also arise through perturbations of androgenic gland hormone and sexual differentiation in later development. The causes of intersex are multifaceted and can occur through a number of mechanisms including parasitism, environmental sex determination, genetic abnormalities and increasingly pollution is being implicated. Despite many studies on the effects of endocrine disrupters on crustaceans, very few have focussed on wild populations or male related endpoints; rather many laboratory studies have been attempting to assess biomarkers of feminisation. This is surprising as many of the seminal papers on endocrine disruption focussed on effects found in the wild and male specimens. This paper argues that we might have been addressing the right questions (i.e. pollution induced intersex), but in the wrong way (feminisation); and therefore gives recommendations for future directions for research. Biomarker development has been hampered by paucity of genomic and endocrine knowledge of many crustacean model species; however this is rapidly changing with the advent of cheaper affordable genomic techniques and high throughput sequencing.

The discovery of new deep-sea hydrothermal vent communities in the southern ocean and implications for biogeography

A survey of Antarctic waters along the East Scotia Ridge in the Southern Ocean reveals a new vent biogeographic province among previously uncharacterized deep-sea hydrothermal vent communities.

Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-ocean ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian Ocean, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The Southern Ocean is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different oceans but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the Southern Ocean using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other oceans, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in Antarctic marine invertebrates, suggesting that the environmental conditions of the Southern Ocean may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the Antarctic vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than previously recognised.

Deep-sea hydrothermal vents are mainly associated with seafloor spreading at mid-ocean ridges and in basins near volcanic island arcs. They host animals found nowhere else that derive their energy not from the sun but from bacterial oxidation of chemicals in the vent fluids, particularly hydrogen sulphide. Hydrothermal vents and their communities of organisms have become important models for understanding the origins and limits of life as well as evolution of island-like communities in the deep ocean. We describe the fauna associated with high-temperature hydrothermal vents on the East Scotia Ridge, Southern Ocean, to our knowledge the first to be discovered in Antarctic waters. These communities are dominated by a new species of yeti crab, stalked barnacles, limpets and snails, sea anemones, and a predatory seven-armed starfish. Animals commonly found in hydrothermal vents of the Pacific, Atlantic, and Indian Oceans, including giant Riftia tubeworms, annelid worms, vent mussels, vent crabs, and vent shrimps, were not present at the Southern Ocean vents. These discoveries suggest that the environmental conditions of the Southern Ocean may act as a barrier to some vent animals and that the East Scotia Ridge communities form a new biogeographic province with a unique species composition and structure.

Total mercury levels in selected tissues of some marine crustaceans from Persian Gulf, Iran: variations related to length, weight and sex

Much of the variation in trace metal tissue concentrations in marine invertebrates has been attributed to the variety in individual organism size, age and sex. This study assessed the relationship between total mercury (Hg) concentrations in edible tissue, exoskeleton and viscera with length, weight and gender for 69 samples of crustaceans, Penaeus semisulcatus (n = 30), Thenus orientalis (n = 21) and Portunus pelagicus (n = 18) from the northern part of the Persian Gulf. Significant increase in the Hg level in muscle and viscera (r > 0.65, p < 0.01) with an increase in length and weight for all three species. No relationship was found between the Hg level in exoskeleton and length or weight. Significantly higher Hg levels (p < 0.01) were found in female P. semisulcatus than in males (muscle and viscera), but no gender differences were found for the other two species.

Mercury emission factors from intensive shrimp aquaculture and their relative importance to the Jaguaribe River Estuary, NE Brazil

This study estimated Hg emission factors (EFs) and total Hg loading to the Jaguaribe Estuary, NE Brazil, from intensive shrimp farming, and compares this with other local anthropogenic activities. The EF reached 83.5 mg ha(-1) cycle(-1) (about 175 mg ha(-1) year(-1)), resulting in an annual Hg load to the estuary of 0.35 kg. The calculated EF is comparable to Hg EFs from urban wastewaters (200 mg ha(-1)) and solid waste disposal (400 mg ha(-1) year(-1)) from cities located in the estuary's basin. However, due to the smaller area of aquaculture (2,010 ha), total annual loads are much lower than from these other sources (75 and 150 kg year(-1), respectively). Since shrimp farming effluents are released directly into the estuary, the estimated high EF raises environmental concerns with this expanding industry, suggesting the inclusion of this element in ongoing environmental monitoring programs.

Benthic foraminifera distribution in a tourist lagoon in Rio de Janeiro, Brazil: a response to anthropogenic impacts

Rodrigo de Freitas Lagoon, located in the Rio de Janeiro City, receives several types of polluted discharges. The knowledge of the sediment microfauna correlated with heavy metal and organic matter concentrations could supply important data about the conditions of the lagoon. The benthic foraminiferal assemblage presented larger diversity and more abundant samples in the lagoon entrance than in the inner area. The Ammonia tepida - Elphidium excavatum foraminiferal assemblage is characterized by dwarf, corroded and weak organisms. Agglutinated species were found only near the entrance. Low abundance values and sterility of five samples in the inner area (north/northeast) can be caused by high levels of heavy metals and organic matter. A. tepida shows negative correlation with increasing heavy metals values. PAHs and coprostanol high indexes, and the absence or low presence of microfauna in samples around the lagoon margin confirm illegal flows from gas stations and domestic sewage.

The influences of various anthropogenic sources of deterioration on meiobenthos (Ostracoda) over the last 100 years in Suo-Nada in the Seto Inland Sea, southwest Japan

This study focuses on the relationships of water and sediment quality with meiobenthos (Ostracoda) over the past 100 years, using a sediment core obtained from Suo-Nada in the Seto Inland Sea, Japan. We compared high-resolution ostracode results with geochemical and sedimentological data obtained from the study core as well as with rich environmental monitoring data that are available. R-mode cluster analysis revealed two bioassociations (BC, KA). Until the 1960 s, assemblages continued to show high diversity. They changed in approximately 1970, when excessive nutrients and organic matter began to be supplied, and most species decreased in number. All species of bioassociation BC were dominant again by the mid-1990 s; however, those of bioassociation KA containing infaunal species did not increase and have been absent or rare since the 1970s because organic pollution of sediments has continued to date. This study provided robust baseline for ostracode-based long-term environmental monitoring in East Asia.

Performance of a constructed wetland in treating brackish wastewater from commercial recirculating and super-intensive shrimp growout systems

A recirculating aquaculture system was developed for treating Pacific white shrimp (Litopenaeus vannamei) production wastewater using an integrated vertical-flow (IVF) and five connected integrated horizontal flow (IHF) constructed wetlands as water treatment filters for mesohaline conditions (8.25‰-8.26‰ salinity). The constructed wetlands demonstrated the ability to reduce total nitrogen, total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphorous, chemical oxygen demand, and total suspended solids to levels significantly lower than those in effluents from culture tanks. Various water quality parameters in the culture tanks were deemed suitable for shrimp culture. The actual ratio of wetland area (A(w)) to culture tank area (A(t)) was 1.1439, and the estimated optimal ratio A(w)/A(t) was approximately 1. The IVF-IHF wetlands showed flexibility and reliability in consistently removing the main pollutants from commercial recirculating and super-intensive shrimp growout systems throughout the culture period.

[Accumulation and degradation of organochorine pesticides in shellfish culture environment in Xiamen sea area]

By using GC-ECD, the concentrations of organochlorine pesticides hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in the shellfish culture environment (sea water, sediments, and culture-shellfishes) in Xiamen sea area were analyzed, and the accumulation and degradation patterns of the HCH and DDT were preliminarily approached. In the sea area, there existed remarkable differences in the accumulation and degradation of HCH and DDT among different shellfish culture environments, being mostly associated with the habitation environment and physiological life habits of shellfish. The accumulated HCH isomers (Rx > 1) were mainly beta-HCH, delta-HCH, and gamma-HCH, whereas the degraded HCH isomers (Rx < 1) were mainly alpha-HCH. The ratio of alpha-HCH to gamma-HCH was less than or equal to 1.0, suggesting that the HCH was come from industrial HCH and lindane, most of the HCH had remained in the culture environment for a longer time, and a small amount of lindane was imported. The DDT in the sea water was aerobically degraded, its main degradation product was DDE, and the ratios of (DDD+DDE) to DDTs (p,p-DDE+p,p-DDD+o,p-DDT+p,p-DDT) was less than 0.5, whereas the DDT in sediments and shellfishes was anaerobically degraded, its main degradation product was DDD, and the ratios of (DDD+DDE) to DDTs was greater than 0.5, suggesting that there was a small amount of DDT newly imported in the sea water, and most DDT in sediments and shellfishes were already degraded and transformed into DDD and DDE. There were definite differences in the degradation rates of HCH isomers in the culture environment, suggesting the conformational change of HCH in its transformation processes in the shellfish culture ecosystem.

External morphology of Lightiella monniotae (Crustacea, Cephalocarida) in the light of Cambrian 'Orsten' crustaceans

The species-poor meiofaunal Cephalocarida have played an important role in discussions of the phylogeny and evolution of Crustacea since their discovery in 1955. One reason may be that the morphology of cephalocarids includes some aspects of putatively ancient appearance, such as the simple roof-shaped head shield, the anterior three head appendages resembling those of a nauplius larva, or the trunk-limb-like second maxilla. Cephalocarida have even been suggested to represent the sister taxon to all other Eucrustacea. Presence of possibly plesiomorphic characters, however, does not necessarily point to a basal position in the system. Growing evidence demonstrates that the modification of the fourth post-antennular cephalic appendage, the 'maxilla', into a "mouth part" may have occurred independently in the different eucrustacean lineages, so a trunk-limb-like maxilla is an ancient feature that does not hold only for cephalocarids. Retention of its plesiomorphic shape and function in the Cephalocarida remains, however, noteworthy. Cephalocarids are still little studied and incompletely known, especially their external morphology. By examining several adults and one young specimen of Lightiella monniotae Cals and Delamare Deboutteville, 1970 from New Caledonia, we aimed to a) document as many details as possible, and b) compare these data with other species of Cephalocarida. We also aimed to reconstruct aspects of the ground pattern of Cephalocarida, which is a pre-requisite for any comparisons in a broader perspective of crustacean phylogeny. Among the new findings or conclusions are: (1) Lightiella is in need of a revision since several assumed differences between the species are questionable or subject to intra-specific variability; (2) the cuticle of the trunk-limb basipod is sub-divided into a number of smaller sclerotized areas as in various exceptionally 3D preserved fossil crustaceans from Cambrian 'Orsten' faunal assemblages; (3) a small transitional portion on the post-maxillulary limbs in the area where the endopod and basipod connect is discussed as either a reduced, proximal endopod segment or as an evolutionary new joint of the basipod to enhance its flexibility; (4) the so-called pseud-epipod is interpreted as an outer branch of the exopod; (5) compared to 'Orsten' crustaceans many characters of the Cephalocarida are more modified than previously assumed, including the morphology of the trunk-limb basipod, and the unique, ring-shaped appearance of the abdominal segments. Also the development is not as plesiomorphic as sometimes assumed, at least not compared to that of the strictly anamorphic series of the 'Orsten' eucrustacean Rehbachiella kinnekullensis. The application of SEM techniques has again proved to be especially appropriate because of the small size of these animals, and because it permits direct comparisons with other similarly small crustaceans and the 'Orsten' crustaceans and their larvae.

[Spatiotemporal distribution of macrobenthic communities and its relationships with environmental factors in Sanmen Bay]

In November 2006 and in January, April, and August 2007, an investigation on the macrobenthic communities was conducted at 18 stations in Sanmen Bay to study the relationships between the macrobenthic communities and environmental factors. A total of 124 taxa were collected, including 44 species of Polychaeta, 34 species of Crustacea, 22 species of Mollusca, 11 species of Echinodermata, and 13 species of others. The species of Polychaeta and Mollusca accounted for 62.9% of the total, which constituted the main population of the communities. Aglaophamus dibranchis, Capitella capitata, and Sternaspis scutata were the dominant species in spring, Sternaspis scutata, Aglaophamus dibranchis, and Spionidae spp. were the dominant species in summer, S. scutata, C. capitata, A. dibranchis and Virgularia gustaviana were the dominant species in autumn, and A. dibranchis, S. scutata, C. capitata, and Spionidae spp. were the dominant species in winter. There was a significant difference in the average biomass and average density of the macrobenthic communities between different seasons. The annual average biomass was 17.36 g x m(-2) and the annual average density was 72 ind x m(-1). The diversity indices of the macrobenthic communities also differed significantly between different seasons. The seasonal average Shannon diversity index was from 1.53 to 1.89, seasonal average Margalef species richness index was from 2. 25 to 2. 96, and seasonal average Pielou evenness index was from 0.83 to 0.94. Canonical correspondence analysis showed that the sea water temperature, salinity, and dissolved inorganic nitrogen, and the organic matter, total nitrogen, and total phosphorus in surface sediment were the main environmental factors affecting the macrobenthic communities. Environmental variables could better explain the changes of main macrobenthic species.

Life cycle assessment of Chinese shrimp farming systems targeted for export and domestic sales

We conducted surveys of six hatcheries and 18 farms for data inputs to complete a cradle-to-farm-gate life cycle assessment (LCA) to evaluate the environmental performance for intensive (for export markets in Chicago) and semi-intensive (for domestic markets in Shanghai) shrimp farming systems in Hainan Province, China. The relative contribution to overall environmental performance of processing and distribution to final markets were also evaluated from a cradle-to-destination-port perspective. Environmental impact categories included global warming, acidification, eutrophication, cumulative energy use, and biotic resource use. Our results indicated that intensive farming had significantly higher environmental impacts per unit production than semi-intensive farming in all impact categories. The grow-out stage contributed between 96.4% and 99.6% of the cradle-to-farm-gate impacts. These impacts were mainly caused by feed production, electricity use, and farm-level effluents. By averaging over intensive (15%) and semi-intensive (85%) farming systems, 1 metric ton (t) live-weight of shrimp production in China required 38.3 ± 4.3 GJ of energy, as well as 40.4 ± 1.7 t of net primary productivity, and generated 23.1 ± 2.6 kg of SO(2) equiv, 36.9 ± 4.3 kg of PO(4) equiv, and 3.1 ± 0.4 t of CO(2) equiv. Processing made a higher contribution to cradle-to-destination-port impacts than distribution of processed shrimp from farm gate to final markets in both supply chains. In 2008, the estimated total electricity consumption, energy consumption, and greenhouse gas emissions from Chinese white-leg shrimp production would be 1.1 billion kW·h, 49 million GJ, and 4 million metric tons, respectively. Improvements suggested for Chinese shrimp aquaculture include changes in feed composition, farm management, electricity-generating sources, and effluent treatment before discharge. Our results can be used to optimize market-oriented shrimp supply chains and promote more sustainable shrimp production and consumption.

Regulation of crustacean molting: a review and our perspectives

Molting is a highly complex process that requires precise coordination to be successful. We describe the early classical endocrinological experiments that elucidated the hormones and glands responsible for this process. We then describe the more recent experiments that have provided information on the cellular and molecular aspects of molting. In addition to providing a review of the scientific literature, we have also included our perspectives.

[Macrozoobenthos functional groups in intertidal flat of northwest Jiaozhou Bay]

Based on the survey of macrozoobenthos at 35 locations of 7 sections in the intertidal flat of northwest Jiaozhou Bay in February, May, August, and November 2009, three zones including high tidal zone (A), mid tidal zone (B, C, and D), and low tidal zone (E) were selected to study the functional groups of macrozoobenthos in the flat. A total of 71 macrozoobenthos species were recorded, most of which were of mollusk (31 species), polychaete (20 species), and crustacean (14 species). The species number in A, B, C, D, and E was 26, 33, 35, 38, and 31, respectively. According to their food preferences, the macrozoobenthos were classified into 4 functional groups, i. e., planktonphagous, carnivorous, omnivorous, and detritivorous. The percentage of the species number of each functional group in the total species number of macrozoobenthos was in the order of carnivorous > planktophagous > detritivorous > omnivorous. Carnivorous group had the highest species diversity index, while omnivorous group had the lowest one. Overall, the species richness index, evenness index, and species diversity index were higher in mid tidal zone and lower in high and low tidal zones. The present study showed that the distribution of macrozoobenthos functional groups varied with the environment of tidal zones, being an integrative reflection of their habitat conditions.

The non-native seaweed Asparagopsis armata supports a diverse crustacean assemblage

This is the first study describing the crustacean fauna associated to Asparagopsis armata, a non-native, red seaweed widely distributed along western Mediterranean coasts. First found in Australia and New Zealand, it was introduced naturally through the Strait of Gibraltar and rapidly spread out. A one-year spatio-temporal study (Feb 08-Feb 09) was carried out in the Strait of Gibraltar to characterize the spatio-temporal patterns of the associated crustacean fauna. Maximum biomass of A. armata was measured during April-June, whereas the maximum crustacean abundances were registered from June-October. In total 41 crustacean species were identified. The caprellid Caprella penantis, traditionally associated to non-polluted areas, was more abundant on Tarifa Island (higher values of dissolved oxygen and pH) than in Algeciras (lower oxygen and pH). The gammarid Podocerus variegatus was dominant in Algeciras Bay while Hyale schmidti and Apherusa mediterranea were the most abundant on Tarifa Island. Among isopods, Synisoma nadejda was only found on Tarifa Island. When compared with literature of native algae of the intertidal and shallow sublittoral, the species richness of associated crustaceans was similar in A. armata and the natives. Very little is known about the influence of this algae on altering marine communities, so complete faunistic studies dealing with other groups such as polychaetes or molluscs are necessary to properly address biogeographical, ecological and management programmes dealing with this non-native species.

Biodiversity of the deep-sea continental margin bordering the Gulf of Maine (NW Atlantic): relationships among sub-regions and to shelf systems

BACKGROUND

In contrast to the well-studied continental shelf region of the Gulf of Maine, fundamental questions regarding the diversity, distribution, and abundance of species living in deep-sea habitats along the adjacent continental margin remain unanswered. Lack of such knowledge precludes a greater understanding of the Gulf of Maine ecosystem and limits development of alternatives for conservation and management.

METHODOLOGY/PRINCIPAL FINDINGS

We use data from the published literature, unpublished studies, museum records and online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf of Maine (39-43°N, 63-71°W, 150-3000 m depth); (2) compare patterns of taxonomic diversity and distribution of megafaunal and macrofaunal species among six distinct sub-regions and to the continental shelf; and (3) estimate the amount of unknown diversity in the region. Known diversity for the deep-sea region is 1,671 species; most are narrowly distributed and known to occur within only one sub-region. The number of species varies by sub-region and is directly related to sampling effort occurring within each. Fishes, corals, decapod crustaceans, molluscs, and echinoderms are relatively well known, while most other taxonomic groups are poorly known. Taxonomic diversity decreases with increasing distance from the continental shelf and with changes in benthic topography. Low similarity in faunal composition suggests the deep-sea region harbours faunal communities distinct from those of the continental shelf. Non-parametric estimators of species richness suggest a minimum of 50% of the deep-sea species inventory remains to be discovered.

CONCLUSIONS/SIGNIFICANCE

The current state of knowledge of biodiversity in this deep-sea region is rudimentary. Our ability to answer questions is hampered by a lack of sufficient data for many taxonomic groups, which is constrained by sampling biases, life-history characteristics of target species, and the lack of trained taxonomists.

[Effects of sediment dredging on benthos community structure and water quality in Zhushan Bay]

We surveyed the changes of macro-benthos community composition and nutrients concentration in water in Zhushan Bay after it had been dredged 6 months, which aimed to remove the polluted surface sediments. The results showed that the main benthos in the dredged and un-dredged sediments were Limodrilus hoffmeisteri, Pelopia and Bellamya aeruginosa; compared to the un-dredged sediments, the bio-diversity of dredged areas became lower. However, its biomass became higher than that in un-dredged areas. Concentration range changes of TN and TP in overlying water was 1.64-4.45 mg/L and 0.133-0.258 mg/L, respectively. The post-dredged sediments were still in a higher state of nutrients for the higher concentration nutrients in overlying water, macro-benthos were the species that lived in a serious polluted water environment. Using Shannon-Weaver, Simpson, and Goodnight benthic index to evaluate the results show that the dredged area is in the moderately polluted level, but un-dredged area is in the middle-heavily polluted level. According to the benthos fauna surveys and water quality monitoring results, the effective of sediment dredging could play its role only the strict control on the external pollution resources have been made and reduces the effects of polluted water on the sediments.

Monitoring acute and chronic water column toxicity in the Northern Sacramento-San Joaquin Estuary, California, USA, using the euryhaline amphipod, Hyalella azteca: 2006 to 2007

After the significant population decline of several pelagic fish species in the Northern Sacramento-San Joaquin (SSJ) Estuary (CA, USA) in 2002, a study was performed to monitor water column toxicity using the amphipod Hyalella azteca. From January 1, 2006 to December 31, 2007, water samples were collected biweekly from 15 to 16 sites located in large delta channels and main-stem rivers, selected based on prevalent distribution patterns of fish species of concern. Ten-day laboratory tests with H. azteca survival and relative growth as toxicity endpoints were conducted. The enzyme inhibitor piperonyl butoxide ([PBO], 25 µg/L) was added to synergize or antagonize pyrethroid or organophosphate (OP) insecticide toxicity, respectively. Significant amphipod mortality was observed in 5.6% of ambient samples. Addition of PBO significantly changed survival or growth in 1.1% and 10.1% of ambient samples, respectively. Sites in the Lower Sacramento River had the largest number of acutely toxic samples, high occurrence of PBO effects on amphipod growth (along with sites in the South Delta), and the highest total ammonia/ammonium concentrations (0.28 ± 0.15 mg/L). Ammonia/ammonium, or contaminants occurring in mixture with these, likely contributed to the observed toxicity. Pyrethroid insecticides were detected at potentially toxic concentrations. Overall, results of this study identified specific areas and contaminants of concern and showed that water in the Northern SSJ Estuary was at times acutely toxic to sensitive invertebrates.

Evaluation of the toxicity of river and creek sediments in Hungary with two different methods

The aim of this study is to compare the responses of two different ecotoxicological methods for the determination of the toxic hazard of river or creek sediments in Hungary. Since water quality is intrinsically linked to sediment quality, the ecotoxicological control of sediments is also very important in the water quality policy. The 2000/60 EC Water Framework Directive aims at achieving a good qualitative and quantitative status of all water bodies by 2015. Fifteen sediments and four sludges were collected at different sites in Hungary, which are contaminated by industrial sewage. The first assay is the acute toxicity test with the crustacean Daphnia magna Straus (OECD 202) using larvae less than 1 day old, and an exposure time of 2 days. The second assay is the Ostracodtoxkit F with freshly hatched larvae of the crustacean Heterocypris incongruens and an exposure time of 6 days. The Ostracodtoxkit F test is a "direct sediment contact" bioassay, in which the test organisms are in continuous contact with the sediments. The Daphnia tests were applied on water extracts of the sediment without any contact of the test organisms with the contaminated sediment. The same 1:4 water/sediment ratio has been applied to both tests. The results showed higher toxic effects of the sediments to H. incongruens than to D. magna confirming the need to complement "water only" tests with "solid phase" assays for a meaningful evaluation of the toxic hazard of aquatic environments. The sensitivity of H. incongruens is similar to that of the other test species which are currently used for solid-phase assays. The growth inhibition of H. incongruens is a very sensitive endpoint for sediment toxicity testing. The sediment toxicity tested by ostracods showed strong correlation with concentration of total chromium, lead, and cadmium together.

High sensitivity of Gammarus sp. juveniles to deltamethrin: outcomes for risk assessment

Amphipods from the genus Gammarus are among the most frequently used organisms in ecotoxicological testing and in situ bioindication. Because of their importance in risk assessment, it is necessary to understand the potential roles of life stage, population source and inter-specific differences on the sensitivity of these organisms to contaminants. In the present study, the acute toxicity of deltamethrin, a commonly used pyrethroid insecticide, has been tested for Gammarus fossarum and Gammarus pulex (Crustacea, Amphipoda) to document the inter- and intra-specific variability at different developmental stages. Adult G. fossarum were about two-fold more sensitive to deltamethrin than adult G. pulex, 96-h LC50 being 33.2 and 68.0 ng L(-1), respectively. However, in the same species, significant differences of sensitivity were observed between individuals from different locations. Furthermore, G. fossarum from certain localities were less sensitive to deltamethrin than certain G. pulex. In addition, juveniles of both species were about 14- to 22-fold more sensitive to deltamethrin than adults: 48-h LC50 in G. fossarum and G. pulex juveniles were 4.0 and 5.7 ng L(-1). Therefore, lethal effects of deltamethrin on Gammarus sp. populations likely depend more on juvenile response rather than on adult response. Since juveniles were also the most abundant population component, the present results show that risk assessment should consider at this developmental stage.

[Standing crop and spatial distribution of meiofauna in Yellow Sea at late stage of Enteromorpha prolifera bloom in 2008]

An investigation was made on the standing crop, spatial distribution, sediment environment of meiofauna at 33 stations (including 22 stations in cold water mass area and 9 stations in Enteromorpha prolifera bloom area) in the Yellow Sea at the late stage of E. prolifera bloom in summer 2008. In this southern Yellow Sea area which was seriously impacted by the green algal bloom, the silt and clay contents in the sediments in 2008 had an obvious increase, compared with those in 2007, and the sediment chlorophyll-a and phaeophytin a contents in 2008 did not show obvious changes in cold water mass area but distinctly decreased in southern Jiangsu inshore area and Yangtze River estuary. Within the total 16 meiofaunal groups sorted, no marked variation was observed in their vertical distribution and in the contribution of each group to the total meiofauna. In 2008, the average abundance of meiofauna was (1375 +/- 793) ind x 10 cm(-2), and the biomass was (1203 +/- 707) micro x 10 cm(-2), both of which were decreased by about 1/3, compared with those in 2007. The meiofaunal standing crop was decreased more obviously in the stations heavily affected by the E. prolifera bloom, while that in the Yellow Sea cold water mass area was slightly increased, resulting in an unusual trend of meiofaunal standing crop decreasing from the central area of cold water mass to the inshore area in the southern Yellow Sea. By contrast, and as usual, the meiofaunal standing crop was increased from the cold water mass area to the inshore area in the northern Yellow Sea. Statistical analyses suggested that only the meiofaunal abundance had positive correlation with the salinity in the stations heavily affected by the green algal bloom. Our study indicated that macroalgal bloom obviously inhibited the standing crop of meiofauna in the inshore area. The decrease was not due to the deficiency of food concentration, but likely caused by the deposition and degradation of the E. prolifera bloom.

Effect of salinity on survival and growth of blue crab, Callinectes amnicola from Lagos Lagoon, Nigeria

The effect of salinity on the survival and growth of Callinectes amnicola (De Rocheburne) from the Lagos Lagoon, Nigeria was monitored in the laboratory for 22 weeks. The crabs were euryhaline and tolerated a salinity range of 5 to 25 per thousand and had 90% survival at 15 and 20 per thousand. The highest gain in weight (173.0%) and carapace width (56.1%) was obtained at salinity of 15 per thousand. The highest specific growth rate (1.98) was obtained at 15 per thousand, while the lowest specific growth rate (-0.28) was recorded at 35 per thousand. The condition factor of the crabs showed a fairly consistent pattern at the different salinity levels with values ranging from 5.7 to 7.3. Complete moulting was obtained at salinity of 15 per thousand in the 12th week of the experiment. The crab with carapace width of 6.8 cm increased to 8.1 cm (19.1%) after moulting.

A eucrustacean metanauplius from the Lower Cambrian

A new eucrustacean arthropod, Wujicaris muelleri gen. et sp. nov, is represented by a Lower Cambrian early metanauplius of strikingly modern morphology despite being the oldest known fossil of such an early immature crustacean larva. The morphology of the metanauplius closely mirrors that of corresponding developmental stages of living barnacles and copepods, and it is likely that its appendages had a similar function for feeding and locomotion. The metanauplius larva demonstrates remarkable stasis in morphology, life history, and lifestyle of (small) eucrustaceans over 525 million years, probably as a result of adaptation to a long-lasting physical niche and regime involving low Reynolds numbers and laminar current flow.

Toxicity of metal pyrithione photodegradation products to marine organisms with indirect evidence for their presence in seawater

We evaluated the acute toxicities of the metal pyrithiones (MePTs)--copper pyrithione (CuPT) and zinc pyrithione (ZnPT)--to four species of marine algae and a marine crustacean (Tigriopus japonicus). We also performed acute toxicity tests using six of the main MePT photodegradation products: pyridine-N-oxide (PO); 2-mercaptopyridine (HPS); pyridine-2-sulfonic-acid (PSA); 2-mercaptopyridine-N-oxide (HPT); 2,2'-dithio-bis-pyridine ([PS](2)); and 2,2'-dithio-bis-pyridine-N-oxide ([PT](2))-and three marine organisms representing three trophic levels: an alga (Skeletonema costatum), a crustacean (T. japonicus), and a fish (Pagrus major). The acute toxicity values (72-h EC(50)) of CuPT, ZnPT, HPT, (PT)(2), (PS)(2), HPS, PO, and PSA for S. costatum, which was the most sensitive of the test organisms to the chemicals tested, were 1.5, 1.6, 1.1, 3.4, 65, 730, >100,000, and >100,000 microg l(-1), respectively. CuPT was detected in the growth media used for S. costatum tests and in seawater containing HPT or (PT)(2); the concentration of CuPT in seawater containing HPT was highly dependent on the Cu(2+) concentration. These results indicate that in the presence of sufficient Cu(2+), the toxicities of HPT and (PT)(2) should be assessed as CuPT because in Japan MePTs are most frequently used as antifouling booster biocides in conjunction with cuprous oxide.

Factors influencing epibenthic assemblages in the Minho Estuary (NW Iberian Peninsula)

The epibenthic community of the Minho Estuary was studied during the summer of 2006. Diversity was generally low and a total of 14 fish and five crustacean taxa were identified. Multivariate analysis revealed two site clusters (A and B). Water conductivity and percentage of fine sand were the abiotic variables that most contributed to the spatial distinction between clusters. The species contributing the most to the average similarity within Cluster A were Crangon crangon and Pomatoschistus microps, while in Cluster B was Atyaephyra desmarestii. Possible factors responsible for the low diversity of the epibenthic community in Minho Estuary were the low macrozoobenthic abundance and diversity, and the high abiotic oscillations between tides (mainly salinity) acting on the ecosystem.

Fish and macro-crustacean communities and their dynamics in the Severn Estuary

The species of fish and macro-crustacean living within the Severn Estuary are reviewed. The fish community is notably species rich and exceeds 100 species in total for the estuary. Standardised long-term sampling at Hinkley Point in Bridgwater Bay gives a total complement of 83 for a single locality and this number is increasing by about one new species every two years. Most of these new species are moving in from centres of population lying to the south of the estuary. Almost all species of fish and macro-crustacean living within the estuary undertake regular migrations so that they tend to move seasonally in waves up and down the estuary. For fish, both species richness and the total abundance reach a maximum in late summer and autumn. The timing of this peak varies between the upper and lower estuary. This seasonal maximum is primarily caused by the arrival of the new recruits which use the estuary as a nursery. In contrast, crustaceans tend to be at their most diverse and abundant in early to mid summer. Using a 30-year time series of fish and crustacean abundance collected at Hinkley Point it is shown that major changes in the structure of the community are now underway and there are considerable recent changes in the abundance. However, some abundant species, including sand goby, Pomatoschistus spp., whiting, Merlangius merlangus and sprat, Sprattus sprattus, the three most abundant species in the estuary, have shown no long-term trend. At present, approximately 20% of the fish and macro-crustaceans observed in Bridgwater Bay are undergoing rapid, typically exponential, change in abundance. For a numerically abundant, diverse, fauna composed of approximately 90 species such levels of change are unexpected and suggest that the system is presently far from equilibrium. In some cases, the observed changes can be related to recent warming and the North Atlantic Oscillation. The overall increase in fish abundance observed may reflect a general improvement in water quality and a reduction in other anthropogenic impacts such as mortality in cooling-water intakes. The potential impacts of tidal power generation in the Severn Estuary are reviewed. There is considerable potential for any major installation to impact the fish and crustacean populations as they migrate and also alter the nature of the habitat resulting in changes in community composition. A particular difficulty in predicting the future impact of harnessing tidal energy is that the present community is already changing rapidly. The ability of fish and crustaceans to pass through the turbines unharmed will be a key issue in an assessment of the impact of tidal power generation.

Semisubmersible oil platforms: understudied and potentially major vectors of biofouling-mediated invasions

Biofouling has long been recognised as a major pathway for the introduction of non-indigenous species. This study records the decapods and stomatopod crustaceans fouling a semisubmersible oil platform dry docked for hull cleaning in Jurong Port, Singapore. Of the 25 species of decapods identified, 13 were non-indigenous and represent new records to Singapore waters. Of these, the crabs Glabropilumnus seminudus and Carupa tenuipes are known to be invasive in other parts of the world. The stomatopod, Gonodactylaceus randalli, is the first mantis shrimp recorded in a biofouling community. The richness and diversity of this fouling community, consisting of many vagile species, highlights the difference between platforms and ships. With the expansion of maritime oil and gas exploration, the threat posed by an expanded fleet of semisubmersible oil platforms translocating non-indigenous fouling communities across biogeographical boundaries is very serious. Scientists, policy-makers, and stakeholders should turn their attention to this growing problem.

Does the survivorship of activated resting stages in toxic environments provide cues for ballast water treatment?

The toxic effects of three inorganic metals (Cu, Cr, Hg), three organic (phenol, formalin, ammonium) chemicals, ozone-enriched water and peroxides (H2O2) on embryonic development were tested in 8 species from the Porifera, Bryozoa and Crustacea. Toxicants with lower molecular weight showed stronger negative impacts on post-diapause embryos than chemicals with higher molecular weight if related to the toxicity of the chemicals to active adult stages. Only few embryos of the cladoceran Moina macrocopa and none of the cladoceran Wlassicsia pannonica treated with peroxides at concentration 0.3% developed further. Ozone-enriched water had no significant effect on post-diapause embryonic development in cladocerans. Ammonium (the product of NH4OH dissociation) in concentration 100 mg/l and higher killed all embryos of M. macrocopa inside protective membranes. Peroxides and ammonium are suggested for the purification of ship ballast waters as effective, non-expensive and non-persistent toxic chemicals. Resting stages of invertebrates including at least Crustaceans, Porifera and Bryozoa seem to allow not only dispersal among toxic industrial environments such as ship ballast compartments, but may also endure serious pollution events common in seaports and estuaries. Artemia cysts due to their strong protection against different toxic substances are recommended as a model for studies of toxic effects in diapausing stages in polluted estuaries and marine environments.

Changes in the benthic macroinvertebrate fauna of a large microtidal estuary following extreme modifications aimed at reducing eutrophication

An artificial channel was opened in 1994 between the microtidal Peel-Harvey Estuary and the Indian Ocean to increase tidal exchange and thus ameliorate the problems of eutrophication. Although this greatly reduced macroalgal and cyanobacterial growths and the amount of particulate organic matter, our data indicate that, contrary to managerial expectations, the benthic environment has deteriorated. Thus, although macroinvertebrate density has declined as predicted, taxonomic distinctness (Delta( *)) has also declined and species composition has become more variable. Macroinvertebrate composition has also changed markedly at the species, family and even phylum levels. The Crustacea, the most sensitive of the major macrobenthic taxa to environmental stress, has become proportionally less abundant and speciose, whereas the Polychaeta, the least sensitive, was unique in showing the reverse trend. The benthos of the Peel-Harvey Estuary is thus apparently more stressed than previously, probably due to the multiple effects of a great increase in system use.

Effects of antimony on aquatic organisms (Larva and embryo of Oryzias latipes, Moina macrocopa, Simocephalus mixtus, and Pseudokirchneriella subcapitata)

Antimony is widespread in aquatic environment. Trivalent forms of antimony are known to be more toxic than other chemical species of antimony. In the present study, antimony potassium tartrate (APT), the trivalent inorganic forms of antimony, was selected as a test antimony compound due to its high water solubility. The effects of antimony on Japanese medaka (Oryzias latipes), planktonic crustacea (Moina macrocopa and Simocephalus mixtus), and green algae (Pseudokirchneriella subcapitata) were evaluated. Larval survival and the embryonic development were measured for fish assay. APT was less toxic to larval medaka (24-h LC50, 261; 48-h LC50, 238 mg L(-1)). Simocephalus mixtus was killed by very low concentrations of APT (24-h LC50, 4.92 mg L(-1)), and antimony was also toxic to Moina macrocopa (24-h LC50, 12.83 mg L(-1)). Toxicities of APT to S. mixtus and Moina macrocopa were about 50 and 20 times more toxic to Oryzias latipes larvae, respectively, in terms of 24-h LC50 value. Growth inhibition of Pseudokirchneriella subcapitata was observed in the presence of APT (72-h EC50, 206 mg L(-1)). This study demonstrated that APT is more toxic to planktonic crustacea than fish and green algae, and planktonic crustacea appears a better indicator of antimony pollution in aquatic environment.

Effects of environmentally relevant concentrations of nonylphenol on growth and 20-hydroxyecdysone levels in mysid crustacean, Americamysis bahia

We investigated the effects of environmentally relevant concentrations of nonylphenol (NP) on survival, growth, sexual development and molting of the mysid Americamysis bahia (Crustacea: Mysidacea), including assay of 20-hydroxyecdysone (20E) levels. Seven-day-old mysids were exposed to NP concentrations of 0.3, 1, 3, 10 and 30 microg/L for 14 days. Among growth-related traits we assayed, an effect on body length was the most prominent, with the effects observed at concentrations as low as 1 microg/L NP. In addition, the total number of molting exposed to NP for 14 days was significantly decreased in the treatment groups at 10 or 30 microg/L relative to the controls. These results clearly indicate that subchronic exposure to environmentally relevant concentrations of NP affects growth of mysids. Furthermore, we investigated the effect of NP on production of 20E in female mysids during the molting period. Production of 20E in pre-molting mysids exposed to 30 microg/L of NP was lower than those in control groups, and exposure of female mysids to NP disrupted molting cycles. Taken together, the results suggest that environmentally relevant concentrations of NP can disrupt growth of A. bahia via inhibition of 20E levels and an associated delay in molting.

Tolerance of Physocypria kraepelini (Crustacean, Ostracoda) to water-borne ammonia, phosphate and pH value

This study evaluated the median lethal concentration (LC50) and safe concentration of water-borne ammonia, phosphate and pH value on Physocypria kraepelini, a freshwater Ostracoda with a static renewal test system. The results indicated that the LC50 values of ammonia for P kraepelini were 1026.71, 859.98, 771.79 and 583.82 mg/L at 24, 48, 72 and 96 h exposure, respectively, and the safe concentration range of ammonia for the long-term survival of P. kraepelini was less than 58.38 mg/L. The safe range of pH value for the survival of P. kraepelini was from 6.59 to 7.61. P. kraepelini has a high tolerance to ammonia, phosphate and pH value which are the main environmental factors in the serious eutrophication water.

Evaluation of zoobenthic assemblages and recovery following petroleum spill in a coastal area of Río de la Plata estuarine system, South America

The objective of this work was to analyse zoobenthic assemblages in the coastal sector of the Río de La Plata, Argentina, after a petroleum spill. Sampling stations were located in representative sites of various landscapes. Structure, composition, physico-chemical parameters and seasonal changes were recorded in order to assess taxocenosis evolution during the period 1999-2003. Recovery signs were estimated by means of biotic indices and the presence of sensitive species. Tolerant species were dominant in heavily polluted sites, with low diversity and water quality values, according to the biotic indices used. In certain zones, sediment quality remains impoverished, with a visible oil film on the surface. However, during the last sampling, some points showed an increase in biotic indices, pointing to a slight improvement in environmental conditions.

[Ecological character of pelagic mysids in Yangtze Estuary of China]

Based on the four seasonal oceanographic cruises investigation data in the Yangtze Estuary (122 degrees 00'-123 degrees 30' E, 29 degrees 00'-32 degrees 00' N) in 2002-2003, the diversity and abundance dynamics of pelagic mysids as well as their relationships with fishing ground were studied. A total of 14 species were identified, among which, 10 species occurred in autumn, 8 species in spring and summer, and 2 species in winter. Clear seasonal alterations were observed, among which the highest alteration ratio (90.9%) occurred from autumn to winter. Shannon diversity index (H') in spring, summer and autumn was above 2, and that in winter was 1. Mean abundance was the highest in summer [234.70 ind x (100 m3)(-1)], followed by in autumn [103.34 ind x (100 m3)(-1)], spring [80.36 ind x (100 m3)(-1)], and winter [12.40 ind x (100 m3)(-1)]. The changes in mean abundance were in accordance with the fluctuation of seasonal temperature. Due to the adaptation to a wide range of temperature and salinity, Gastrosaccus pelagicus was dominant in spring, autumn and winter. Acanthomysis brevirostris was dominant in summer and autumn, and A. longirostrisas in winter. The dominant species in each season all made a significant contribution to total abundance. A. brevirostris was observed in large agglomerates in summer. As a kind of fish diet, mysids were of importance in the formation of fishing grounds in the Yangtze Estuary and Zhoushan Islands.

First maxillae suction discs in Branchiura (Crustacea): development and evolution in light of the first molecular phylogeny of Branchiura, Pentastomida, and other "Maxillopoda"

The fish ectoparasites Branchiura (Crustacea) display two different ways of attachment to the fish surface as adults: the first maxillae are either hooks (Dolops) or suction discs (Argulus, Chonopeltis, and Dipteropeltis). In larval Argulus foliaceus the first maxillae are hooks. With the first molecular phylogeny of the Branchiura as a background, the present paper discusses the evolutionary scenarios leading to hooks versus suction discs. Specific homologies exist between larval Argulus foliaceus hooks and adult Dolops ranarum hooks. These include the presence of a comparable number of segments/portions and a distal segment terminating in a double structure: a distal two-part hook (in Argulus) or one hook and an associate spine-like structure (in Dolops). In the phylogenetic reconstruction based on three molecular markers (mitochondrial 16S rRNA, nuclear 18S and 28S rRNA), Dolops ranarum is found to be in a sister group position to all other Branchiura, which in this analysis include six Argulus and one Chonopeltis sequences. Based on the molecular phylogeny a likely evolutionary scenario is that the ancestral branchiuran used hooks (on the first maxilla) for attachment, as seen in Dolops, of which the proximal part was subsequently modified into suction discs in Argulus and Chonopeltis (and Dipteropeltis). The sister group relationship of the Branchiura and Pentastomida is confirmed based on the most comprehensive taxon sampling until now. No evidence was found for a branchiuran in-group position of the Pentastomida.

Assessment of the effects of soil PAH accumulation by a battery of ecotoxicological tests

Surface soils were collected at remote, urban and industrial sites in the Southern of Italy in order to evaluate PAH concentrations and assess the toxic effects by a battery of ecotoxicological tests. The tests were performed on whole soils and on both organic and aqueous extracts. Further goal of this study was to integrate the results coming from each test and matrix in a synthetic toxicity index. The highest summation sigmaPAH concentrations were measured at the industrial soil, although this one did not show an high ecotoxicological risk. Among the performed tests, the phytotoxicity tests showed the highest sensitivity. For whole soil, the worst case always has been represented by test through bacteria. Our results could represent the first step toward the selection of a proper battery to characterize the soil ecotoxicological risk.

Is surface orientation a determinant for colonisation patterns of vagile and sessile macrobenthos on artificial reefs?

In order to examine how substratum colonisation can affect community structure, a 1-year study was conducted at the Faro/Ancao artificial reef (Algarve, Portugal). In the study of hard substratum communities, motile species are usually neglected and only the conspicuous species are taken into account. Therefore, the development of vagile and sessile components of the epibiotic community were analysed separately. Differences between assemblages on horizontal surfaces, but not on vertical surfaces, were detected. Multivariate analysis detected differences in macrobenthic community structure either considering sessile or motile components. However, significant differences were only detected for vagile fauna. Moreover, this study suggests that for hard substratum communities, analysis of the vagile fauna is important and should be taken into account in the functioning of the artificial raft.