Gene expression plasticity facilitates acclimatization of a long-lived Caribbean coral across divergent reef environments

Local adaptation can increase fitness under stable environmental conditions. However, in rapidly changing environments, compensatory mechanisms enabled through plasticity may better promote fitness. Climate change is causing devastating impacts on coral reefs globally and understanding the potential for adaptive and plastic responses is critical for reef management. We conducted a four-year, three-way reciprocal transplant of the Caribbean coral Siderastrea siderea across forereef, backreef, and nearshore populations in Belize to investigate the potential for environmental specialization versus plasticity in this species. Corals maintained high survival within forereef and backreef environments, but transplantation to nearshore environments resulted in high mortality, suggesting that nearshore environments present strong environmental selection. Only forereef-sourced corals demonstrated evidence of environmental specialization, exhibiting the highest growth in the forereef. Gene expression profiling 3.5 years post-transplantation revealed that transplanted coral hosts exhibited profiles more similar to other corals in the same reef environment, regardless of their source location, suggesting that transcriptome plasticity facilitates acclimatization to environmental change in S. siderea. In contrast, algal symbiont (Cladocopium goreaui) gene expression showcased functional variation between source locations that was maintained post-transplantation. Our findings suggest limited acclimatory capacity of some S. siderea populations under strong environmental selection and highlight the potential limits of coral physiological plasticity in reef restoration.

Dissecting the resilience of barley genotypes under multiple adverse environmental conditions

As climate change increases abiotic stresses like drought and heat, evaluating barley performance under such conditions is critical for maintaining productivity. To assess how barley performs under normal conditions, drought, and heat stress, 29 different varieties were examined, considering agronomic, physiological, and disease-related characteristics. The research was conducted in five environments: two normal environments in 2020/2021 and 2021/2022, two drought stress environments in 2020/2021 and 2021/2022, and one heat stress environment in 2021/2022. The results demonstrated that genotype and environment significantly influenced all traits (p < 0.05), except canopy temperature, while genotype x environment interaction significantly influenced most traits, except total chlorophyll content and canopy temperature. Heat and drought stress environments often resulted in reduced performance for traits like plant height, spike length, grains per spike, and 100-grain weight compared to normal conditions. Based on individual traits, genotypes 07UT-44, 06WA-77, 08AB-09, and 07N6-57 exhibited the highest grain yield (4.1, 3.6, 3.6, and 3.6 t/ha, respectively). Also, these genotypes demonstrated enhanced stability in diverse drought and heat stress conditions, as assessed by the mean performance vs. stability index (Weighted Average of Absolute Scores, WAASB). The multi-trait stability index (MTSI) identified 07UT-44, 07UT-55, 07UT-71, and 08AB-09 as the most stable genotypes in terms of the performance of all traits. The imported lines demonstrated superior performance and stability, highlighting their potential as valuable genetic resources for developing climate-resilient barley.

Multi-site assessment of soil nitrogen stocks across temperate forests under different thinning intensities, recovery times, and site conditions

Increasing research interests have been paid to understand the factors controlling soil nitrogen (N) stocks under diverse environmental conditions and forest thinning regimes. This study investigated soil N stocks across 13 temperate forests, each of which received three thinning intensities (unthinned control, 15-30 %, and 30-50 % basal area removals) under varying pre-treatment conditions (altitude, slope, soil pH, soil moisture, stand age, stand density, diameter at breast height, and tree height). The total N stored in the forest floor (L, F, and H layers) and mineral soils (0-10, 10-20, and 20-30 cm) was determined 1, 4, and 7 years after thinning. Given the various site conditions and thinning regimes, a standardized effect size was used to analyze the influences of thinning on N stocks. The N stocks (Mg N ha^-1) of the forest floor and at 0-10, 10-20, and 20-30 cm mineral soil depths were 0.02-0.46, 0.32-3.21, 0.29-3.03, and 0.25-2.54 across all studied forests, respectively. The averaged effect sizes indicated decrease in forest floor N stocks and increase in mineral soil N stocks under thinning due to the reduced litterfall and eventual input of thinning residues. Thinning intensity negatively affected the effect sizes for the N stocks (P < 0.05), suggesting that excessively heavy thinning may be inappropriate for retaining forest soil N. However, multimodel inference showed that soil pH (relative importance = 1.00) and stand age (relative importance = 0.42) had the largest influence on the effect sizes for forest floor and mineral soil N stocks. This pattern suggests that the effects of thinning on soil N stocks might vary with pre-treatment conditions, even more than thinning intensities and recovery time; therefore, thinning to manage forest soil N should consider pre-treatment environmental conditions in addition to thinning regime.

A review of the order mysida in marine ecosystems: What we know what is yet to be known

Mysids have a high ecological importance, particularly by their role in marine food chains as a link between the benthic and pelagic realms. Here we describe the relevant taxonomy, ecological aspects such as distribution and production, and their potential as ideal test organisms for environmental research. We also highlight their importance in estuarine communities, trophic webs, and their life history, while demonstrating their potential in addressing emergent problems. This review emphasizes the importance of mysids in understanding the impacts of climate change and their role in the ecology of estuarine communities. Although there is a dearth of research in genomic studies, this review emphasizes the relevance of mysids and their potential as a model organism in environmental assessment studies of prospective or retrospective nature and highlights the need for further research to enhance our understanding of this group's ecological significance.

Corals at the edge of environmental limits: A new conceptual framework to re-define marginal and extreme coral communities

The worldwide decline of coral reefs has renewed interest in coral communities at the edge of environmental limits because they have the potential to serve as resilience hotspots and climate change refugia, and can provide insights into how coral reefs might function in future ocean conditions. These coral communities are often referred to as marginal or extreme but few definitions exist and usage of these terms has therefore been inconsistent. This creates significant challenges for categorising these often poorly studied communities and synthesising data across locations. Furthermore, this impedes our understanding of how coral communities can persist at the edge of their environmental limits and the lessons they provide for future coral reef survival. Here, we propose that marginal and extreme coral communities are related but distinct and provide a novel conceptual framework to redefine them. Specifically, we define coral reef extremeness solely based on environmental conditions (i.e., large deviations from optimal conditions in terms of mean and/or variance) and marginality solely based on ecological criteria (i.e., altered community composition and/or ecosystem functioning). This joint but independent assessment of environmental and ecological criteria is critical to avoid common pitfalls where coral communities existing outside the presumed optimal conditions for coral reef development are automatically considered inferior to coral reefs in more traditional settings. We further evaluate the differential potential of marginal and extreme coral communities to serve as natural laboratories, resilience hotspots and climate change refugia, and discuss strategies for their conservation and management as well as priorities for future research. Our new classification framework provides an important tool to improve our understanding of how corals can persist at the edge of their environmental limits and how we can leverage this knowledge to optimise strategies for coral reef conservation, restoration and management in a rapidly changing ocean.

Thermal performance with depth: Comparison of a mesophotic scleractinian and an antipatharian species subjected to internal waves in Mo'orea, French Polynesia

Local thermal environment has a strong influence on the physiology of marine ectotherms. This is particularly relevant for tropical organisms living close to their thermal optimum, well exemplified by the increasing frequency of bleaching occurrence in shallow-water corals. Mesophotic Coral Ecosystems (MCEs) were suggested as potential oases, especially when they are submitted to internal waves inducing short-term cooling events. Indeed, probability of bleaching occurrence in scleractinians was reported to decrease with depth in Mo'orea as temperature variability increases. However, ecophysiological data are currently lacking to understand the cause of lower susceptibility/increased plasticity of deeper corals. A growing interest has been devoted the last decade to MCEs, but our understanding of the physiological performance of benthic organisms living in this environment remains relatively unexplored. To tackle that question, we first compared the metabolic responses (dark respiration, net photosynthesis and photosynthetic efficiency) of the depth-generalist scleractinian Pachyseris speciosa from two heterogeneous thermal environment (25 and 85 m depths) to acute heat stress to determine if the local thermal environment could predict coral response to warming. Then, we tested the thermal performance of two sympatric species (the scleractinian P. speciosa and the antipatharian Stichopathes sp.) to determine if there are inter-species differences in performances in species experiencing identical levels of temperature variability, at mesophotic depths (85 m). Results revealed broader thermal performances in the mesophotic P. speciosa compared to mid-depth ones, and constrained performances in the mesophotic antipatharian compared to the scleractinian species. We hypothesize that the high fluctuations in temperature due to internal waves in deeper areas contribute to the broader thermal performances of mesophotic P. speciosa. However, the constrained performances of the mesophotic antipatharian compared to P. speciosa suggests that other processes than the symbiosis with zooxanthellae also influence thermal performances of these mesophotic organisms. Our results supported that Stichopathes sp. lives close to its thermal optimum, suggesting a (relatively) cold thermal specialist strategy. In this context, composition of MCEs in the future is unlikely to shift to antipatharian-dominated landscape and will remain coral-dominated landscape.

Fine-scale heterogeneity reveals disproportionate thermal stress and coral mortality in thermally variable reef habitats during a marine heatwave

Increasing ocean temperatures threaten coral reefs globally, but corals residing in habitats that experience high thermal variability are thought to be better adapted to survive climate-induced heat stress. Here, we used long-term ecological observations and in situ temperature data from Heron Island, southern Great Barrier Reef to investigate how temperature dynamics within various thermally variable vs. thermally stable reef habitats change during a marine heatwave and the resulting consequences for coral community survival. During the heatwave, thermally variable habitats experienced larger surges in daily mean and maxima temperatures compared to stable sites, including extreme hourly incursions up to 36.5 °C. The disproportionate increase in heat stress in variable habitats corresponded with greater subsequent declines in hard coral cover, including a three-times greater decline within the thermally variable Reef Flat (70%) and Deep Lagoon (83%) than within thermally stable habitats along sheltered and exposed areas of the reef slope (0.3-19%). Interestingly, the thermally variable Reef Crest experienced comparatively small declines (26%), avoiding the most severe tidal ponding and resultant heat stress likely due to proximity to the open ocean equating to lower seawater residence times, greater mixing, and/or increased flow. These results highlight that variable thermal regimes, and any acclimatization or adaptation to elevated temperatures that may lead to, do not necessarily equate to protection against bleaching and mortality during marine heatwaves. Instead, thermally stable habitats that have greater seawater exchange with the open ocean may offer the most protection to corals during the severe marine heatwaves that accompany a changing climate.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00338-022-02328-6.

A Hybrid Epidemic Model to Explore Stochasticity in COVID-19 Dynamics

The dynamic nature of the COVID-19 pandemic has demanded a public health response that is constantly evolving due to the novelty of the virus. Many jurisdictions in the USA, Canada, and across the world have adopted social distancing and recommended the use of face masks. Considering these measures, it is prudent to understand the contributions of subpopulations—such as “silent spreaders”—to disease transmission dynamics in order to inform public health strategies in a jurisdiction-dependent manner. Additionally, we and others have shown that demographic and environmental stochasticity in transmission rates can play an important role in shaping disease dynamics. Here, we create a model for the COVID-19 pandemic by including two classes of individuals: silent spreaders, who either never experience a symptomatic phase or remain undetected throughout their disease course; and symptomatic spreaders, who experience symptoms and are detected. We fit the model to real-time COVID-19 confirmed cases and deaths to derive the transmission rates, death rates, and other relevant parameters for multiple phases of outbreaks in British Columbia (BC), Canada. We determine the extent to which SilS contributed to BC’s early wave of disease transmission as well as the impact of public health interventions on reducing transmission from both SilS and SymS. To do this, we validate our model against an existing COVID-19 parameterized framework and then fit our model to clinical data to estimate key parameter values for different stages of BC’s disease dynamics. We then use these parameters to construct a hybrid stochastic model that leverages the strengths of both a time-nonhomogeneous discrete process and a stochastic differential equation model. By combining these previously established approaches, we explore the impact of demographic and environmental variability on disease dynamics by simulating various scenarios in which a COVID-19 outbreak is initiated. Our results demonstrate that variability in disease transmission rate impacts the probability and severity of COVID-19 outbreaks differently in high- versus low-transmission scenarios.

Parasitism by metacercariae modulates the morphological, organic and mechanical responses of the shell of an intertidal bivalve to environmental drivers

Environmental variation alters biological interactions and their ecological and evolutionary consequences. In coastal systems, trematode parasites affect their hosts by disrupting their life-history traits. However, the effects of parasitism could be variable and dependent on the prevailing environmental conditions where the host-parasite interaction occurs. This study compared the effect of a trematode parasite in the family Renicolidae (metacercariae) on the body size and the shell organic and mechanical characteristics of the intertidal mussels Perumytilus purpuratus, inhabiting two environmentally contrasting localities in northern and central Chile (ca. 1600 km apart). Congruent with the environmental gradient along the Chilean coast, higher levels of temperature, salinity and pCO₂, and a lower pH characterise the northern locality compared to that of central Chile. In the north, parasitised individuals showed lower body size and shell resistance than non-parasitised individuals, while in central Chile, the opposite pattern was observed. Protein level in the organic matter of the shell was lower in the parasitised hosts than in the non-parasitised ones regardless of the locality. However, an increase in polysaccharide levels was observed in the parasitised individuals from central Chile. These results evidence that body size and shell properties of P. purpuratus vary between local populations and that they respond differently when confronting the parasitism impacts. Considering that the parasite prevalence reaches around 50% in both populations, if parasitism is not included in the analysis, the true response of the host species would be masked by the effects of the parasite, skewing our understanding of how environmental variables will affect marine species. Considering parasitism and identifying its effects on host species faced with environmental drivers is essential to understand and accurately predict the ecological consequences of climate change.

Times and partners are a-changin': relationships between declining food abundance, breeding success, and divorce in a monogamous seabird species

Seabirds exhibit considerable adjustment capacity to cope with environmental changes during the breeding season and to maximize lifetime reproductive output. For example, divorce has been proposed to be an adaptive behavioral strategy in social monogamous species, as a response to poor conditions and low breeding success. Here, we studied divorce at the population and individual levels in northern gannets (Morus bassanus, hereafter gannets) nesting on Bonaventure island (Quebec, Canada). At the population level, we used Granger's method for detecting and quantifying temporal causality between time series (from 2009 to 2019) of divorce rate and breeding success of gannets (n = 809) and we evaluated the relationship between breeding success and biomass of their two principal prey (Atlantic mackerel, Scomber scombrus, and Atlantic herring, Clupea harengus). Our results indicated that breeding success is mainly influenced by the spawning-stock biomass of Atlantic mackerel, and a decrease in breeding success is followed by an increase in divorce rate with a 1-year lag. However, the effect of the interaction between breeding success and year on the proportion of individuals that divorced showed significant inter-annual variation. At the individual level, our results support the adaptive strategy hypothesis of divorce. Indeed, gannets that changed partners did so following a reproductive failure, and there was an increase in breeding success 1 year following the divorce. Being central place foragers, opportunities for dispersal and adaptation are often limited for breeding seabirds in a context of low food abundance. We suggest that behavioral flexibility expressed as divorce would be an efficient short-term strategy for maintaining reproductive performance.

Post-survey Likert constructions: an adaptive method for generalizing perceptions of environmental variability

Environmental perceptions are inherently based on an individual's existing knowledge, experiences, and future expectations. Methods for measuring environmental perception, therefore, must capture a range of experiences while also being flexible enough to integrate these experiences into a coherent unit for analysis. Many research topics require cross-cultural comparisons in order to corroborate findings; however, assessments of environmental perception are often place- and context-specific. We propose here post-survey Likert constructions (PSLCs), using semi-structured interviews to construct a five-point scale system from multiple household responses after the completion of interviews. This method is able to capture the natural variability in the population using the respondents' own language and characterizations of phenomena. We applied this method to measure the perceived environmental variability of residents living in a dynamic flooding landscape in the Okavango Delta, Botswana. The PSLC method captures the differences in environmental perception in a location with different settlement and cultural histories, multiple language groups, and different environmental conditions. The method easily transfers to other environments and populations, allowing for potential cross-cultural comparisons of perceived environmental variability. This publication responds to calls for increased transparency in reporting the development, execution, advantages, and disadvantages of methods related to environmental change.

Transgenerational effects of temperature fluctuations in Arabidopsis thaliana

Plant stress responses can extend into the following generations, a phenomenon called transgenerational effects. Heat stress, in particular, is known to affect plant offspring, but we do not know to what extent these effects depend on the temporal patterns of the stress, and whether transgenerational responses are adaptive and genetically variable within species. To address these questions, we carried out a two-generation experiment with nine Arabidopsis thaliana genotypes. We subjected the plants to heat stress regimes that varied in timing and frequency, but not in mean temperature, and we then grew the offspring of these plants under controlled conditions as well as under renewed heat stress. The stress treatments significantly carried over to the offspring generation, with timing having stronger effects on plant phenotypes than stress frequency. However, there was no evidence that transgenerational effects were adaptive. The magnitudes of transgenerational effects differed substantially among genotypes, and for some traits the strength of plant responses was significantly associated with the climatic variability at the sites of origin. In summary, timing of heat stress not only directly affects plants, but it can also cause transgenerational effects on offspring phenotypes. Genetic variation in transgenerational effects, as well as correlations between transgenerational effects and climatic variability, indicates that transgenerational effects can evolve, and have probably already done so in the past.

Phage strategies facilitate bacterial coexistence under environmental variability

Bacterial communities are often exposed to temporal variations in resource availability, which exceed bacterial generation times and thereby affect bacterial coexistence. Bacterial population dynamics are also shaped by bacteriophages, which are a main cause of bacterial mortality. Several strategies are proposed in the literature to describe infections by phages, such as "Killing the Winner", "Piggyback the loser" (PtL) or "Piggyback the Winner" (PtW). The two temperate phage strategies PtL and PtW are defined by a change from lytic to lysogenic infection when the host density changes, from high to low or from low to high, respectively. To date, the occurrence of different phage strategies and their response to environmental variability is poorly understood. In our study, we developed a microbial trophic network model using ordinary differential equations (ODEs) and performed 'in silico' experiments. To model the switch from the lysogenic to the lytic cycle, we modified the lysis rate of infected bacteria and their growth was turned on or off using a density-dependent switching point. We addressed whether and how the different phage strategies facilitate bacteria coexistence competing for limiting resources. We also studied the impact of a fluctuating resource inflow to evaluate the response of the different phage strategies to environmental variability. Our results show that the viral shunt (i.e. nutrient release after bacterial lysis) leads to an enrichment of the system. This enrichment enables bacterial coexistence at lower resource concentrations. We were able to show that an established, purely lytic model leads to stable bacterial coexistence despite fluctuating resources. Both temperate phage models differ in their coexistence patterns. The model of PtW yields stable bacterial coexistence at a limited range of resource supply and is most sensitive to resource fluctuations. Interestingly, the purely lytic phage strategy and PtW both result in stable bacteria coexistence at oligotrophic conditions. The PtL model facilitates stable bacterial coexistence over a large range of stable and fluctuating resource inflow. An increase in bacterial growth rate results in a higher resilience to resource variability for the PtL and the lytic infection model. We propose that both temperate phage strategies represent different mechanisms of phages coping with environmental variability. Our study demonstrates how phage strategies can maintain bacterial coexistence in constant and fluctuating environments.

Effects of environmental variability on superspreading transmission events in stochastic epidemic models

Superspreaders (individuals with a high propensity for disease spread) have played a pivotal role in recent emerging and re-emerging diseases. In disease outbreak studies, host heterogeneity based on demographic (e.g. age, sex, vaccination status) and environmental (e.g. climate, urban/rural residence, clinics) factors are critical for the spread of infectious diseases, such as Ebola and Middle East Respiratory Syndrome (MERS). Transmission rates can vary as demographic and environmental factors are altered naturally or due to modified behaviors in response to the implementation of public health strategies. In this work, we develop stochastic models to explore the effects of demographic and environmental variability on human-to-human disease transmission rates among superspreaders in the case of Ebola and MERS. We show that the addition of environmental variability results in reduced probability of outbreak occurrence, however the severity of outbreaks that do occur increases. These observations have implications for public health strategies that aim to control environmental variables.

Seagrass Cymodocea nodosa across biogeographical regions and times: Differences in abundance, meadow structure and sexual reproduction

Seagrasses are key habitat-forming species of coastal areas. While previous research has demonstrated considerable small-scale variation in seagrass abundance and structure, studies teasing apart local from large-scale variation are scarce. We determined how different biogeographic scenarios, under varying environmental and genetic variation, explained variation in the abundance and structure (morphology and biomass allocation), epiphytes and sexual reproduction intensity of the seagrass Cymodocea nodosa. Regional and local-scale variation, including their temporal variability, contributed to differentially explain variation in seagrass attributes. Structural, in particular morphological, attributes of the seagrass leaf canopy, most evidenced regional seasonal variation. Allocation to belowground tissues was, however, mainly driven by local-scale variation. High seed densities were observed in meadows of large genetic diversity, indicative of sexual success, which likely resulted from the different evolutionary histories undergone by the seagrass at each region. Our results highlight that phenotypic plasticity to local and regional environments need to be considered to better manage and preserve seagrass meadows.

Toxigenic phytoplankton groups and neurotoxin levels related to two contrasting environmental conditions at the coastal area of Rio de Janeiro (west of South Atlantic)

An assessment of the major pigments and neurotoxins and a description of the phytoplankton community were carried out within the coastal region of Rio de Janeiro State (Brazil), during winter and the following spring of 2018. Overall, six stations were investigated for oceanographic conditions (with CTD casts). Filtered water samples were used to estimate the chlorophyll a (CHL-a), carotenoids (CAR), and phycobiliproteins (PHY) using UV-Vis spectrophotometry, as well as the quantification of saxitoxins (STX) and domoic acid (DA), through High Performance Liquid Chromatography (HPLC). Planktonic organisms were counted using sedimentation chambers of different volumes and an inverted microscope. A cluster analysis, SIMPER, and ANOSIM were applied to the phytoplankton data along with diversity indexes, and non-parametric statistics to phycotoxins and pigments. There was a significant difference between the winter and spring phytoplankton community, associated with the mixed layer depth (r² = -0.626, p < 0.05) and temperature (r² = 0.641, p < 0.05). Phytoplankton biomass and C:CHL-a indicated a higher production during the winter than in spring, with the potentially toxic genus Pseudo-nitzschia responsible for 12.79% of autotrophic abundance (SIMPER output). Pigments showed a slight increase in CAR during spring, while PHY remained at trace concentrations. Both the DA and STX were quantified in winter and spring, but with significant differences only for STX between the sampling periods. Among the 71 taxa, 11 were identified as potentially toxic with an emphasis on STX-producing dinoflagellates and cyanobacteria, such as Alexandrium sp., Gymnodinium spp. along with Trichodesmium spp. Season-related environmental variability may be the major driving force modulating the mixed assemblage of species that support different levels of phycotoxins.

Individual and environmental determinants of Cuterebra bot fly parasitism in the eastern chipmunk (Tamias striatus)

Understanding the interactions between parasites, hosts, and their shared environment is central to ecology. Variation in infestation prevalence may be the result of varying environmental and population characteristics; however, variations in parasitism may also depend on individual characteristics that influence both the exposure and susceptibility to parasites. Using 12 years of data from a population of wild eastern chipmunks relying on pulsed food resources, we investigated the determinants of bot fly parasitism at both the population and individual level. We assessed the relationship between infestation prevalence and weather conditions, population size and food abundance. Then, we assessed the relationship between infestation intensity and chipmunk behavior, sex, age, body mass and food abundance. Precipitation, temperature and population size were positively related to infestation prevalence, while beech masts were negatively related to infestation prevalence, highlighting the importance of local environmental conditions on hosts and parasites. We also found that the influence of activity and exploration on infestation intensity varied according to sex in adults. More active and faster exploring males had more parasites compared to females, suggesting that reproductive behaviors may influence parasite exposure. For juveniles, infestation intensity was greater when juveniles emerged in the spring as opposed to fall, possibly because spring emergence is synchronized with the peak of bot fly eggs in the environment, low food availability and longer activity period. Our results suggest that the environmental, population and host characteristics that are advantageous for reproduction and resource acquisition may come at the cost of increasing parasitism.

A new colorimetric DET technique for determining mm-resolution sulfide porewater distributions and allowing improved interpretation of iron(II) co-distributions

Measurement of sulfide in pore waters is critical for understanding biogeochemical processes, especially within coastal sediments. Here we report the development of a new colorimetric DET (diffusive equilibration in thin films) technique for determining mm-resolution, two-dimensional sulfide distributions in sediment pore waters. This colorimetric sulfide DET method was based on the standard spectrophotometric methylene blue assay, but modified to allow quantitation of sulfide by computer imaging densitometry. The method detection and effective upper measurement limits of the optimised technique were 3.7 and 1000 μmol L^-1, respectively. The optimised sulfide DET method was combined with the colorimetric iron(II) DET method to obtain co-distributions in coastal seagrass (Zostera muelleri) colonised sediment under light and dark conditions. In the dark, seagrass sediments were more reduced than in the light, with large areas being dominated by high porewater sulfide concentrations. These co-distributions were compared with those obtained using the previously described DET-DGT (diffusive gradients in thin films) method for measuring iron(II) and sulfide co-distributions. There was less overlap of iron(II) and sulfide distributions using the sulfide DET as the two DET methods are influenced most by the later hours of deployment, whereas the sulfide-DGT measurement integrates concentrations over the whole deployment period. Overlap was most apparent in very dynamic sediment zones, such as burrow wall sediments.

The potential of Glycymeris longior (Mollusca, Bivalvia) as a multi-decadal sclerochronological archive for the Argentine Sea (Southern Hemisphere)

In the absence of instrumental records, shell growth increments of bivalves are used to build continuous multi-decadal time series of growth and to estimate environmental variability. While there is interest in such chronologies in the Northern Hemisphere, there is a lack of multi-decadal datasets of growth for marine species from the Southern Hemisphere. We assessed the potential of the clam Glycymeris longior as an environmental proxy archive for the mid-latitudes of the South Atlantic Ocean, by applying sclerochronological techniques on the shells of individuals from a coastal area in Northern Patagonia, Argentina. Growth of G. longior showed a synchronous pattern, and shells were cross dated. We demonstrated that G. longior shells can be used to generate a robust multi-decadal chronology. The chronology spanned for a period of 22 years, from 1990 to 2011. This chronology has the potential to be extended, given that the maximum longevity of the analysed shells was 69 years. Significant positive correlations were found between the chronology and sea surface temperature and the Southern Annular Mode index. The sclerochronological approach performed in this study is a first step toward a long-term understanding of the links between climate and growth patterns of bivalves in temperate regions of SW Atlantic Ocean, under a long-term perspective.

Geochemical (soil) and phylogenetic (plant taxa) factors affecting accumulation of macro- and trace elements in three natural plant species

A field study was carried out to estimate the variations in the concentrations of macro- and trace elements in the rhizosphere soil and in roots and leaves of three widely distributed plant species-couch grass, plantain, and yarrow collected simultaneously from two sites characterized by different soil parameters. Main attention was paid to environmental (soil characteristics) and phylogenetic (plant species) factors that can influence on the concentrations of different elements in the plants and in soils. Both the factors cannot be considered as independent, although their contribution to the plant elemental composition may be different. There were statistically significant differences between concentrations of C, N, and H and 13 macro- and trace elements in the soils collected from the two sites. The concentrations of many chemical elements in the rhizosphere soil of the three plant species collected from the same site were often different. The differences in the characteristics of the soils at the sites resulted in differences between the concentrations of several elements in the plants growing at the sites. However, this was only one of the reasons of significant difference between the concentrations of macro- and trace elements in the same plant species collected from the sites. Couch grass, plantain, and yarrow had different reactions on the soil characteristics. The elemental composition of each plant species was unique although they grew at the same place and were collected simultaneously. Among the plants, yarrow was more tolerant to varying environmental conditions than plantain and couch grass.

Role of temperature and carbonate system variability on a host-parasite system: Implications for the gigantism hypothesis

Biological interactions and environmental constraints alter life-history traits, modifying organismal performances. Trematode parasites often impact their hosts by inducing parasitic castration, frequently correlated with increased body size in the host (i.e., gigantism hypothesis), which is postulated to reflect the re-allocation of energy released by the reduction in the reproductive process. In this study, we compared the effect of a trematode species on shell size and morphology in adult individuals of the intertidal mussels Perumytilus purpuratus (>20 mm) collected from two local populations of contrasting environmental regimes experienced in central-southern Chile. Our field data indicates that in both study locations, parasitized mussels evidenced higher body sizes (shell length, total weight and volume) as compared with non-parasitized. In addition, parasitized mussels from the southern location evidenced thinner shells than non-parasitized ones and those collected from central Chile, suggesting geographical variation in shell carbonate precipitation across intertidal habitats of the Chilean coast. In laboratory conditions, mussels collected from a local population in central Chile were exposed to two temperature treatments (12 and 18 °C). Parasitized mussels showed higher growth rates than non-parasitized, regardless of the seawater temperature treatments. However, the metabolic rate was not influenced by the parasite condition or the temperature treatments. Our field and laboratory results support the parasite-induced gigantism hypothesis, and suggest that both the thermal environment and geographic location explain only a portion of the increased body size, while the parasitic condition is the most plausible factor modulating the outcome of this host-parasite interaction.

Coral Symbiodinium Community Composition Across the Belize Mesoamerican Barrier Reef System is Influenced by Host Species and Thermal Variability

Reef-building corals maintain a symbiotic relationship with dinoflagellate algae of the genus Symbiodinium, and this symbiosis is vital for the survival of the coral holobiont. Symbiodinium community composition within the coral host has been shown to influence a coral's ability to resist and recover from stress. A multitude of stressors including ocean warming, ocean acidification, and eutrophication have been linked to global scale decline in coral health and cover in recent decades. Three distinct thermal regimes (high_TP, mod_TP, and low_TP) following an inshore-offshore gradient of declining average temperatures and thermal variation were identified on the Belize Mesoamerican Barrier Reef System (MBRS). Quantitative metabarcoding of the ITS-2 locus was employed to investigate differences and similarities in Symbiodinium genetic diversity of the Caribbean corals Siderastrea siderea, S. radians, and Pseudodiploria strigosa between the three thermal regimes. A total of ten Symbiodinium lineages were identified across the three coral host species. S. siderea was associated with distinct Symbiodinium communities; however, Symbiodinium communities of its congener, S. radians and P. strigosa, were more similar to one another. Thermal regime played a role in defining Symbiodinium communities in S. siderea but not S. radians or P. strigosa. Against expectations, Symbiodinium trenchii, a symbiont known to confer thermal tolerance, was dominant only in S. siderea at one sampled offshore site and was rare inshore, suggesting that coral thermal tolerance in more thermally variable inshore habitats is achieved through alternative mechanisms. Overall, thermal parameters alone were likely not the only primary drivers of Symbiodinium community composition, suggesting that environmental variables unrelated to temperature (i.e., light availability or nutrients) may play key roles in structuring coral-algal communities in Belize and that the relative importance of these environmental variables may vary by coral host species.

Dynamic changes in display architecture and function across environments revealed by a systems approach to animal communication

Animal communication is often structurally complex and dynamic, with signaler and receiver behavior varying in response to multiple environmental factors. To date, studies assessing signal dynamics have mostly focused on the relationships between select signaling traits and receiver responses in a single environment. We use the wolf spider Schizocosa floridana to explore the relationships between courtship display form and function across two social contexts (female presence vs absence) and two light environments (light vs dark). We use traditional analytical methods to determine predictors of copulation success (i.e., signal function) and examine these predictors in a structural context by overlaying them on signal phenotype networks (Wilkins et al. 2015). This allows us to explore system design principles (degeneracy, redundancy, pluripotentiality), providing insight into hypotheses regarding complex signal evolution. We found that both social context and light environment affect courtship structure, although the predictors of mating success remain similar across light environments, suggesting system degeneracy. Contrastingly, the same display traits may serve different functions across social environments, suggesting pluripotentiality. Ultimately, our network approach uncovers a complexity in display structure and function that is missed by functional analyses alone, highlighting the importance of systems-based methodologies for understanding the dynamic nature of complex signals.

The importance of local settings: within-year variability in seawater temperature at South Bay, Western Antarctic Peninsula

The Western Antarctic Peninsula (WAP) has undergone significant changes in air and seawater temperatures during the last 50 years. Although highly stenotherm Antarctic organisms are expected to be severely affected by the increase of seawater temperature, high-resolution datasets of seawater temperature within coastal areas of the WAP (where diverse marine communities have been reported) are not commonly available. Here we report on within-year (2016–2017) variation in seawater temperature at three sites on Doumer Island, Palmer Archipelago, WAP. Within a year, Antarctic organisms in South Bay were exposed to water temperatures in excess of 2 °C for more than 25 days and 2.5 °C for more than 10 days. We recorded a temperature range between −1.7° to 3.0 °C. Warming of seawater temperature was 3.75 times faster after October 2016 than it was before October. Results from this study indicate that organisms at South Bay are already exposed to temperatures that are being used in experimental studies to evaluate physiological responses to thermal stress in WAP organisms. Continuous measurements of short to long-term variability in seawater temperature provides important information for parametrizing meaningful experimental treatments that aim to assess the local effects of environmental variation on Antarctic organisms under future climate scenarios.

Comparing in situ colorimetric DET and DGT techniques with ex situ core slicing and centrifugation for measuring ferrous iron and dissolved sulfide in coastal sediment pore waters

In productive coastal sediments the separation between different biogeochemical zones (e.g. oxic, iron(III)-reducing and sulfate-reducing) may be on the scale of millimetres. Conventional measurement techniques simply cannot resolve changes in pore water solute concentrations over such small distances. The diffusive equilibration in thin films (DET) and the diffusive gradients in thin films (DGT) techniques allow in situ determination of pore water solute concentration profiles with one-dimensional profiles and/or two-dimensional distributions on the millimetre scale. Here we compare measurements of pore water iron(II) and sulfide using conventional core sampling (slicing and centrifugation) and colorimetric DET-DGT techniques. DET-DGT samplers were deployed within replicate sediment cores from three different sites, which were processed by slicing and centrifugation following retrieval of the samplers, so that the measurements were approximately co-located. Iron(II) concentrations were determined by DET at all three sites (0.3-262 μmol L^-1), while dissolved sulfide was consistently measured by DGT at one site only (0.003-112 μmol L^-1). Pore water concentrations of iron(II) and sulfide determined conventionally following pore water extraction (iron(II); 0.4-88 μmol L^-1 and sulfide; 0.05-36 μmol L^-1), were systematically lower than the colorimetric DET and DGT measurements in the same sample. This underestimation was most likely due to the mixing of sediment from different biogeochemical zones during pore water extraction, which resulted in the precipitation of iron(II) and sulfide. This study shows that conventional pore water extraction methods can be unreliable for the determination of redox-active solutes due to artefacts associated with pore water mixing.

Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof

Green roofs provide ecosystem services, including stormwater retention and reductions in heat transfer through the roof. Microclimates, as well as designed features of green roofs, such as substrate and vegetation, affect the magnitude of these services. Many green roofs are partially shaded by surrounding buildings, but the effects of this within-roof spatial environmental heterogeneity on thermal performance and other ecosystem services have not been examined. We quantified the effects of spatial heterogeneity in solar radiation, substrate depth and other variables affected by these drivers on vegetation and ecosystem services in an extensive green roof. Spatial heterogeneity in substrate depth and insolation were correlated with differential growth, survival and flowering in two focal plant species. These effects were likely driven by the resulting spatial heterogeneity in substrate temperature and moisture content. Thermal performance (indicated by heat flux and substrate temperature) was influenced by spatial heterogeneity in vegetation cover and substrate depth. Areas with less insolation were cooler in summer and had greater substrate moisture, leading to more favorable conditions for plant growth and survival. Spatial variation in substrate moisture (7%-26% volumetric moisture content) and temperature (21°C-36°C) during hot sunny conditions in summer could cause large differences in stormwater retention and heat flux within a single green roof. Shaded areas promote smaller heat fluxes through the roof, leading to energy savings, but lower evapotranspiration in these areas should reduce stormwater retention capacity. Spatial heterogeneity can thus result in trade-offs between different ecosystem services. The effects of these spatial heterogeneities are likely widespread in green roofs. Structures that provide shelter from sun and wind may be productively utilized to design higher functioning green roofs and increase biodiversity by providing habitat heterogeneity.

In four shallow and mesophotic tropical reef sponges from Guam the microbial community largely depends on host identity

Sponges (phylum Porifera) are important members of almost all aquatic ecosystems, and are renowned for hosting often dense and diverse microbial communities. While the specificity of the sponge microbiota seems to be closely related to host phylogeny, the environmental factors that could shape differences within local sponge-specific communities remain less understood. On tropical coral reefs, sponge habitats can span from shallow areas to deeper, mesophotic sites. These habitats differ in terms of environmental factors such as light, temperature, and food availability, as well as anthropogenic impact. In order to study the host specificity and potential influence of varying habitats on the sponge microbiota within a local area, four tropical reef sponges, Rhabdastrella globostellata, Callyspongia sp., Rhaphoxya sp., and Acanthella cavernosa, were collected from exposed shallow reef slopes and a deep reef drop-off. Based on 16S rRNA gene pyrosequencing profiles, beta diversity analyses revealed that each sponge species possessed a specific microbiota that was significantly different to those of the other species and exhibited attributes that are characteristic of high- and/or low-microbial-abundance sponges. These findings emphasize the influence of host identity on the associated microbiota. Dominant sponge- and seawater-associated bacterial phyla were Chloroflexi, Cyanobacteria, and Proteobacteria. Comparison of individual sponge taxa and seawater samples between shallow and deep reef sites revealed no significant variation in alpha diversity estimates, while differences in microbial beta diversity (variation in community composition) were significant for Callyspongia sp. sponges and seawater samples. Overall, the sponge-associated microbiota is significantly shaped by host identity across all samples, while the effect of habitat differentiation seems to be less predominant in tropical reef sponges.

Individual and mixture effects of selected pharmaceuticals on larval development of the estuarine shrimp Palaemon longirostris

Few ecotoxicological studies incorporate within the experimental design environmental variability and mixture effects when assessing the impact of pollutants on organisms. We have studied the combined effects of selected pharmaceutical compounds and environmental variability in terms of salinity and temperature on survival, development and body mass of larvae of the estuarine shrimp Palaemon longirostris. Drug residues found in coastal waters occur as mixture, and the evaluation of combined effects of simultaneously occurring compounds is indispensable for their environmental risk assessment. All larval stages of P. longirostris were exposed to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DS: 40 and 750 μg L(-1)), the lipid regulator clofibric acid (CA: 17 and 361 μg L(-1)) and the fungicide clotrimazole (CLZ: 0.14 and 4 μg L(-1)). We observed no effect on larval survival of P. longirostris with the tested pharmaceuticals. However, and in contrast to previous studies on larvae of the related marine species Palaemon serratus, CA affected development through an increase in intermoult duration and reduced growth without affecting larval body mass. These developmental effects in P. longirostris larvae were similar to those observed in the mixture of DS and CA confirming the toxic effects of CA. In the case of CLZ, its effects were similar to those observed previously in P. serratus: high doses affected development altering intermoult duration, tended to reduce the number of larval instars and decreased significantly the growth rate. This study suggests that an inter-specific life histories approach should be taken into account to assess the effect of emergent compounds in coastal waters.

Addressing the complexity of water chemistry in environmental fate modeling for engineered nanoparticles

Engineered nanoparticle (ENP) fate models developed to date - aimed at predicting ENP concentration in the aqueous environment - have limited applicability because they employ constant environmental conditions along the modeled system or a highly specific environmental representation; both approaches do not show the effects of spatial and/or temporal variability. To address this conceptual gap, we developed a novel modeling strategy that: 1) incorporates spatial variability in environmental conditions in an existing ENP fate model; and 2) analyzes the effect of a wide range of randomly sampled environmental conditions (representing variations in water chemistry). This approach was employed to investigate the transport of nano-TiO2 in the Lower Rhône River (France) under numerous sets of environmental conditions. The predicted spatial concentration profiles of nano-TiO2 were then grouped according to their similarity by using cluster analysis. The analysis resulted in a small number of clusters representing groups of spatial concentration profiles. All clusters show nano-TiO2 accumulation in the sediment layer, supporting results from previous studies. Analysis of the characteristic features of each cluster demonstrated a strong association between the water conditions in regions close to the ENP emission source and the cluster membership of the corresponding spatial concentration profiles. In particular, water compositions favoring heteroaggregation between the ENPs and suspended particulate matter resulted in clusters of low variability. These conditions are, therefore, reliable predictors of the eventual fate of the modeled ENPs. The conclusions from this study are also valid for ENP fate in other large river systems. Our results, therefore, shift the focus of future modeling and experimental research of ENP environmental fate to the water characteristic in regions near the expected ENP emission sources. Under conditions favoring heteroaggregation in these regions, the fate of the ENPs can be readily predicted.

Foraging behavior links climate variability and reproduction in North Pacific albatrosses

BACKGROUND

Climate-driven environmental change in the North Pacific has been well documented, with marked effects on the habitat and foraging behavior of marine predators. However, the mechanistic linkages connecting climate-driven changes in behavior to predator populations are not well understood. We evaluated the effects of climate-driven environmental variability on the reproductive success and foraging behavior of Laysan and Black-footed albatrosses breeding in the Northwest Hawaiian Islands during both brooding and incubating periods. We assessed foraging trip metrics and reproductive success using data collected from 2002-2012 and 1981-2012, respectively, relative to variability in the location of the Transition Zone Chlorophyll Front (TZCF, an important foraging region for albatrosses), sea surface temperature (SST), Multivariate ENSO Index (MEI), and the North Pacific Gyre Oscillation index (NPGO).

RESULTS

Foraging behavior for both species was influenced by climatic and oceanographic factors. While brooding chicks, both species traveled farther during La Niña conditions, when NPGO was high and when the TZCF was farther north (farther from the breeding site). Models showed that reproductive success for both species showed similar trends, correlating negatively with conditions observed during La Niña events (low MEI, high SST, high NPGO, increased distance to TZCF), but models for Laysan albatrosses explained a higher proportion of the variation. Spatial correlations of Laysan albatross reproductive success and SST anomalies highlighted strong negative correlations (>95 %) between habitat use and SST. Higher trip distance and/or duration during brooding were associated with decreased reproductive success.

CONCLUSIONS

Our findings suggest that during adverse conditions (La Niña conditions, high NPGO, northward displacement of the TZCF), both Laysan and Black-footed albatrosses took longer foraging trips and/or traveled farther during brooding, likely resulting in a lower reproductive success due to increased energetic costs. Our results link climate variability with both albatross behavior and reproductive success, information that is critical for predicting how albatross populations will respond to future climate change.

Age-specific survival and annual variation in survival of female chamois differ between populations

In many species, population dynamics are shaped by age-structured demographic parameters, such as survival, which can cause age-specific sensitivity to environmental conditions. Accordingly, we can expect populations with different age-specific survival to be differently affected by environmental variation. However, this hypothesis is rarely tested at the intra-specific level. Using capture-mark-recapture models, we quantified age-specific survival and the extent of annual variations in survival of females of alpine chamois in two sites. In one population, survival was very high (>0.94; Bauges, France) until the onset of senescence at approximately 7 years old, whereas the two other populations (Swiss National Park, SNP) had a later onset (12 years old) and a lower rate of senescence. Senescence patterns are therefore not fixed within species. Annual variation in survival was higher in the Bauges (SD = 0.26) compared to the SNP populations (SD = 0.20). Also, in each population, the age classes with the lowest survival also experienced the largest temporal variation, in accordance with inter-specific comparisons showing a greater impact of environmental variation on these age classes. The large difference between the populations in age-specific survival and variation suggests that environmental variation and climate change will affect these populations differently.

Effects of sampling method on foliar δ (13)C of Leymus chinensis at different scales

Stable carbon isotope composition (δ (13)C) usually shows a negative relationship with precipitation at a large scale. We hypothesized that sampling method affects foliar δ (13)C and its response pattern to precipitation. We selected 11 sites along a precipitation gradient in Inner Mongolia and collected leaves of Leymus chinensis with five or six replications repeatedly in each site from 2009 to 2011. Additionally, we collected leaves of L. chinensis separately from two types of grassland (grazed and fenced) in 2011. Foliar δ (13)C values of all samples were measured. We compared the patterns that foliar δ (13)C to precipitation among different years or different sample sizes, the differences of foliar δ (13)C between grazed and fenced grassland. Whether actual annual precipitation (AAP) or mean annual precipitation (MAP), it was strongly correlated with foliar δ (13)C every year. Significant difference was found between the slopes of foliar δ (13)C to AAP and MAP every year, among the slopes of foliar δ (13)C to AAP from 2009 to 2011. The more samples used at each site the lower and convergent P-values of the linear regression test between foliar δ (13)C and precipitation. Furthermore, there was significant lower foliar δ (13)C value in presence of grazed type than fenced type grassland. These findings provide evidence that there is significant effect of sampling method to foliar δ (13)C and its response pattern to precipitation of L. chinensis. Our results have valuable implications in methodology for future field sampling studies.

Environmental risk analysis of oil handling facilities in port areas. Application to Tarragona harbor (NE Spain)

Diffuse pollution from oil spills is a widespread problem in port areas (as a result of fuel supply, navigation and loading/unloading activities). This article presents a method to assess the environmental risk of oil handling facilities in port areas. The method is based on (i) identification of environmental hazards, (ii) characterization of meteorological and oceanographic conditions, (iii) characterization of environmental risk scenarios, and (iv) assessment of environmental risk. The procedure has been tested by application to the Tarragona harbor. The results show that the method is capable of representing (i) specific local pollution cases (i.e., discriminating between products and quantities released by a discharge source), (ii) oceanographic and meteorological conditions (selecting a representative subset data), and (iii) potentially affected areas in probabilistic terms. Accordingly, it can inform the design of monitoring plans to study and control the environmental impact of these facilities, as well as the design of contingency plans.

Transitions during cephalopod life history: the role of habitat, environment, functional morphology and behaviour

Cephalopod life cycles generally share a set of stages that take place in different habitats and are adapted to specific, though variable, environmental conditions. Throughout the lifespan, individuals undertake a series of brief transitions from one stage to the next. Four transitions were identified: fertilisation of eggs to their release from the female (1), from eggs to paralarvae (2), from paralarvae to subadults (3) and from subadults to adults (4). An analysis of each transition identified that the changes can be radical (i.e. involving a range of morphological, physiological and behavioural phenomena and shifts in habitats) and critical (i.e. depending on environmental conditions essential for cohort survival). This analysis underlines that transitions from eggs to paralarvae (2) and from paralarvae to subadults (3) present major risk of mortality, while changes in the other transitions can have evolutionary significance. This synthesis suggests that more accurate evaluation of the sensitivity of cephalopod populations to environmental variation could be achieved by taking into account the ontogeny of the organisms. The comparison of most described species advocates for studies linking development and ecology in this particular group.

Spatiotemporal patterns provoked by environmental variability in a predator-prey model

The emergence of spatiotemporal patterns in the distribution of species is one of the most striking phenomena in ecology and nonlinear science. Since it is known that spatial inhomogeneities can significantly affect the dynamics of ecological populations, in the present paper we investigate the impact of environmental variability on the formation of patterns in a spatially extended predator-prey model. In particular, we utilize a predator-prey system with a Holling III functional response and introduce random spatial variations of the kinetic parameter signifying the intrinsic growth rate of the prey, reflecting the impact of a heterogeneous environment. Our results reveal that in the proximity of the Hopf bifurcation environmental variability is able to provoke pattern formation, whereby the coherence of the patterns exhibits a resonance-like dependence on the variability strength. Furthermore, we show that the phenomenon can only be observed if the spatial heterogeneities exhibit large enough regions with high growth rates of the prey. Our findings thus indicate that variability could be an essential pattern formation mechanism of the populations.