Assessing the influence of ocean acidification to marine amphipods: A comparative study

A comprehensive review of the effects of salinity, dissolved organic carbon, pH, and temperature on copper biotoxicity: Implications for setting the copper marine water quality criteria

In recent years, there has been a growing concern about the ecological hazards associated with copper, which has sparked increased interest in copper water quality criteria (WQC). The crucial factors affecting the bioavailability of copper in seawater are now acknowledged to be salinity, dissolved organic carbon (DOC), pH, and temperature. Research on the influence of these four water quality parameters on copper toxicity is rapidly expanding. However, a comprehensive and clear understanding of the relevant mechanisms is currently lacking, hindering the development of a consistent international method to establish the seawater WQC value for copper. As a response to this knowledge gap, this study presents a comprehensive summary with two key focuses: (1) It meticulously analyzes the effects of salinity, DOC, pH, and temperature on copper toxicity to marine organisms. It takes into account the adaptability of different species to salinity, pH and temperature. (2) Additionally, the study delves into the impact of these four water parameters on the acute toxicity values of copper on marine organisms while also reviewing the methods used in establishing the marine WQC value of copper. The study proposed a two-step process: initially zoning based on the difference of salinity and DOC, followed by the establishment of Cu WQC values for different zones during various seasons, considering the impacts of water quality parameters on copper toxicity. By providing fundamental scientific insights, this research not only enhances our understanding and predictive capabilities concerning water quality parameter-dependent Cu toxicity in marine organisms but also contributes to the development of copper seawater WQC values. Ultimately, this valuable information facilitates more informed decision-making in marine water quality management efforts.

A photothermal MoS2 decorated biomass carbon-based aerogel with a directionally aligned porous structure for mitigating heavy metal stress under seawater acidification

Marine animals and human are threatened by seawater acidification and metal contamination. Especially, the toxicity of copper (Cu) is expected to be boosted with seawater acidification. However, studies on the removal of Cu under seawater acidification are limited for practical applications, owing to obstacles such as instability, secondary contamination, and low adsorption efficiency. In this work, coconut shells were utilized for the synthesis of biomass carbon, which was then decorated with MoS2. A novel porous MoS2/carbon-based aerogel (MCA) with the synergistic effect of photothermal conversion and adsorption was constructed via directional freeze-drying technology. The adsorption properties of MCA were a precise match with Freundlich isotherm and pseudo-second-order kinetic models with a high correlation coefficient (R2) of more than 0.995. Under solar illumination, the surface temperature of MCA reached up to 36.3 °C and the adsorption capacity of MCA increased to 833.8 mg g-1, indicating that the remarkable thermal properties of MCA contributed to achieving high adsorption capacity. The adsorption mechanisms of MCA involved in the removal of Cu(ii) ions were dominated by chemisorption rather than surface physical adsorption. Owing to its outstanding photothermal conversion performance and directionally aligned porous structure, MCA was able to remove Cu(ii) species from seawater, and the adsorption ability of MCA reached 247.1 mg g-1 after ten adsorption cycles. MCA exhibited excellent stability to resist the complex natural environment and was easy to reuse. Overall, MCA with a series of merits, including high adsorption efficiency, excellent photothermal conversion property, and outstanding cycling stability, was confirmed to contribute to addressing heavy metal stress under seawater acidification.

Physiological responses of Ampithoe valida and its feeding potential on Ulva prolifera

Large numbers of Amphipoda feed on floating green tide macroalgae in the Yellow Sea, among which Ampithoe valida has a high abundance in the stable and decline periods. Amphipoda preferentially feed on Ulva. Under different temperatures, salinities, and pH, the physiological responses of A. valida and its feeding potential on Ulva prolifera were investigated, along with its physiological responses during green tide blooms in the Southern Yellow Sea. Ampithoe valida could survive within a temperature range of 5-30 °C, salinity of 5-40, and pH of 4-10. Optimal environmental conditions for growth were temperature 15-25 °C, salinity 10-40, and pH 6-10. At temperatures of 5-30 °C, salinities of 5-35, and pH of 4-9, A. valida could effectively reduce U. prolifera biomass. The feeding ability of A. valida was greatest in 25-30 °C, 10-25 salinity, and neutral seawater, exceeding 5 mg·ind.^-1·d^-1. During green tide outbreaks in the Southern Yellow Sea from May to August, the monthly average sea surface temperature, salinity, and pH range is 17.5-27.3 °C, 23.8-29.6, and 7.87-8.17, respectively, within which A. valida showed well growth and could effectively reduce U. prolifera biomass. Finally, this study further discussed the possibility of A. valida as a biological method to control green tide.

Niche breadth and biodiversity change derived from marine Amphipoda species off Iceland

Understanding the ecological requirements and thresholds of individual species is crucial to better predict potential outcomes of climate change on species distribution. In particular, species optima and lower and upper limits along resource gradients require attention. Based on Huisman‐Olff‐Fresco (HOF) models, we determined species‐specific responses along gradients of nine environmental parameters including depth in order to estimate niche attributes of 30 deep‐sea benthic amphipods occurring around Iceland. We, furthermore, examined the relationships between niche breadth, occupancy, and geographic range assuming that species with a wider niche are spatially more widely dispersed and vice versa. Overall, our results reveal that species react very differently to environmental gradients, which is independent of the family affiliation of the respective species. We could infer a strong relationship between occupancy and geographic range and also relate this to differences in niche breadth; that is specialist species with a narrow niche had a more limited distribution and may thus be more threatened by changing environmental conditions than generalist species, which are more widespread. Given the preponderance of rare species in the deep sea, this implies that many species could be at risk. However, this must be carefully weighed against geographical data gaps in this area, given that many deep‐sea areas are severely undersampled and the true distribution of most species is unknown. After all, our results underline that an accurate taxonomic classification is of crucial importance, without which ecological niche properties cannot be determined and which is hence fundamental for the assessment and understanding of changes in biodiversity in the face of increasing human perturbations.

Effects of ocean acidification on the biochemistry, physiology and parental transfer of Ampelisca brevicornis (Costa, 1853)

Ocean acidification (OA) has received more attention in the marine research community in recent years than any other topic. Excess carbon dioxide makes the ocean more acidic, threatening marine ecosystems. There has been little research on the impact of OA on crustaceans, particularly on their physiological and potential ecosystem-level consequences. Thus, we investigated the impacts of OA on the physiological and biochemical characteristics of the estuarine amphipod Ampelisca brevicornis. Ovigerous amphipods were harvested from nature and maintained in the laboratory to produce juveniles, which were then further reared to obtain the mature adults (F0) and successive offspring (F1). For this study, four pH treatments (pH 8.1, 7.5, 7.0, and 6.5) mimicking future OA were evaluated to understand the physiological and biochemical effects on the organisms. The findings of this study suggest that A. brevicornis is more vulnerable to OA than was previously established in short-term trials. The survival was significantly reduced as pH decreased over time and a significant interaction between pH and time was observed. Survival was higher in F1 than in F0 juveniles and vice versa in terms of growth. Animal's physiological responses such as growth, burrowing behavior, locomotor activity, swimming speed, ventilation rate and reproductive performance were negatively influenced by acidification. These physiological characteristics can be linked to the oxidative stress induced by global change conditions because excess of free radicals degrade cell functioning, affecting species' biochemical and physiological performance. These alterations may have long-term negative impacts, with ecological consequences. The results of this study provide baseline information regarding the effect of OA on this keystone crustacean that may be useful in simulating the impacts of OA to develop different conceptual models for a better understanding of the consequences and implications of climate change in the future for managing marine ecosystems.

Biological effects of the antihypertensive losartan under different ocean acidification scenarios

Since the last decade, several studies have reported the presence and effects of pharmaceutical residues in the marine environment, especially those of the antihypertensive class, such as losartan. However, there is little knowledge about the physiological effects of losartan in marine invertebrates regarding its behavior under possible coastal ocean acidification scenarios. The objective of this study was to evaluate biological effects on marine organisms at different levels of the biological organization caused by the compound losartan in water and sediment under coastal ocean acidification scenarios. Water and sediment samples were collected at five sites around the Santos Submarine Sewage outfall (SSO) and two sites around the Guarujá Submarine Sewage Outfall (GSO). Losartan was found in concentrations ranging from <LOD to 7.63 ng/L in water and from <LOQ to 3.10 ng/g in sediments. Statistical analysis showed interactive effects pH and losartan on the toxicity results. The water toxicity test with Echinometra lucunter embryos/larvae showed LOECs 50-100 mg/L, with values decreasing as the pH decreased. In the sediment assays, LOEC value for sea urchin embryo-larval development was 1.0 μg/g for all tested pHs. Regarding the lysosomal membrane stability assays with adult bivalves, a LOEC of 3000 ng/L was found for Perna perna in water exposure (both at pH 8.0 and 7.6). Effects for Mytella guyanensis were observed at environmentally relevant concentrations in sediment (LOEC = 3 ng/g at pH 8.0 and 7.6). This study demonstrated that coastal ocean acidification by itself causes effects on marine invertebrates, but can also increase the negative effects of losartan in waterborne exposure. There is a need to deepen the studies on the ecotoxicity of pharmaceutical residues and acidification of the marine environment.

Experimental evidence of uncertain future of the keystone ragworm Hediste diversicolor (O.F. Müller, 1776) under climate change conditions

It is currently assumed that climate change related factors pose severe challenges to biodiversity maintenance. This paper assesses the multi-stressor effects of elevated temperature (15 °C as control, 25 °C as elevated) and CO₂ levels (pH 8.1 as control, 7.5 and 7.0 representing acidifying conditions) on the physiological (survival and regenerative capacity), behavioral (feeding and burrowing activities), and biochemical changes (metabolic capacity, oxidative status and biotransformation mechanisms) experienced by the keystone polychaete Hediste diversicolor. Temperature rise enlarged the adverse effect of marine acidification on the survival of H. diversicolor, delayed the beginning of the excavation activity, enhancing the negative effects that pH decrease had in the burrowing behavior of this polychaete. Additionally, regardless of the temperature, exposure of H. diversicolor to acidification results in a reduction in the feeding rate. It is the first time that this decreased feeding capacity is found related to seawater acidification in this species. The healing of the wound and the blastemal formation were retarded due to these two climatic factors which hinder the regenerative process of polychaetes. These vital physiological functions of H. diversicolor can be related to the oxidative stress induced by climate change conditions since free radicals overproduced will impair cells functioning, affecting species biochemical and physiological performance, including feeding and tissue regeneration. The present results also demonstrated that although polychaetes' metabolic capacity was enhanced under stress conditions, organisms were still able to increase or maintain their energy reserves. Our findings are of major environmental relevance considering that predicted climate change conditions will affect species vital and ecological and physiological capacities. These can be translated into shrinking not only at the individual and population level but also in microbial and endofaunal diversities, in the detritus processing in estuaries and biogeochemical cycles at the ecosystem level. Thus the conservation of H. diversicolor populations is vital for the normal functioning of estuarine mudflat ecosystems.

Harmful effects of cocaine byproduct in the reproduction of sea urchin in different ocean acidification scenarios

This study has as main objective assessing the toxicity of crack-cocaine combined with different scenarios of ocean acidification on fertilization rate and embryo-larval development of Echinometra lucunter sea urchin. Effects on early life stages were assessed at five different concentrations (6,25 mg.L^-1; 12,5 mg.L^-1; 25 mg.L^-1; 50 mg.L^-1 and 100 mg.L^-1) of crack-cocaine at four different pH values (8.5; 8.0; 7.5; 7.0). The pH values were achieved using two different methodologies: adding hydrochloric acid (HCl) and injecting carbon dioxide (CO₂). The fertilization test did not show significant differences (p ≤ 0.05) compared with control sample at pH values 8.5; 8.0 and 7.5. Results of embryo-larval assays showed a half maximal effective concentration (EC50) of crack-cocaine at pH values tested (8.5, 8.0, 7.5) as 58.83, 10.67 and 11.58 mg/L^-1 for HCl acidification and 58.83, 23.28 and 12.57 mg/L^-1 for CO₂ enrichment. At pH 7.0 the effects observed in fertilization rate and embryo development were associated with the acidification. This study is the first ecotoxicological assessment of illicit drug toxicity in aquatic ecosystems at different ocean acidification scenarios.

Intraspecific variation in the response of the estuarine European isopod Cyathura carinata (Krøyer, 1847) to ocean acidification

In the present study the model isopod, Cyathura carinata were exposed to four pH_NIST treatments (control: 7.9; 7.5, 7, 6.5) in order to determine the tolerance and pH threshold value this estuarine species withstand under future acidification scenarios. Seawater acidification significantly affected the lifespan of C. carinata, where population density was remarkably reduced at the lowest pH treatment. The longevity, survivorship and swimming activity (related to the acquisition of energy) of these isopods decreased with decreasing pH. Furthermore, to determine the possible metabolic plasticity of this species, the swimming activity, the Na+/K + -ATPase activity (relevant for osmoregulation process), and the RNA:DNA ratio (an indicator of fitness) were measure from two populations of C. carinata, one inhabiting a stable environment (pH_NIST 7.5-8.0) and one inhabiting a fluctuating pCO₂ regimes (pH 3.3-8.5) subjected to three pH treatments (7.9, 7.0 and 6.5). The population from high fluctuating pCO₂ conditions showed capacity to withstand to pH 6.5, as well as higher longevity and metabolic plasticity, when compared with the population from the habitat with slight pCO₂ variation. These results indicate that Cyathura population from stable environments could be vulnerable to ocean acidification because it could trigger detrimental effects on its survival energy budget, and growth. However, ocean acidification has limited effect on the energy budget and survival of C. carinata population from highly variable habitats, suggesting that they are able to cope with the elevated energy demand. The difference showed between populations is likely an indication of genetic differentiation in tolerance to ocean acidification, possibly attributable to local adaptations, which could provide the raw material necessary for adaptation to future conditions. In addition, our results suggest that when assessing marine crustacean responses to changing environments on a global scale, variability in population and metabolic responses need to be considered.

Using a mesocosm approach to evaluate marine benthic assemblage alteration associated with CO2 enrichment in coastal environments

The effects of acidification related to the CO₂ enrichment in the coastal environments on marine macrobenthic abundance, diversity and richness were analyzed in a medium- term (21 days) using mesocosm experiments. Two sampling sites located in the Bay of Cadiz - SW, Spain were selected and tested at pH values ranged from 7.9 to 6.0 (± 0.1). Moreover, variations in the concentrations of metals in the sediment samples were analyzed at the end of each experiment. The results showed low variation in the concentrations of metals in the sediment among the pH treatments. A significant decrease (p < 0.05) in the abundance, diversity and richness of assemblages were measured between the control and the lowest pH level in both sampling sites tested in this study (Rio San Pedro and El Trocadero). The majority of species were found in all samples except in pH 6.0 which only two species were found (Hydrobia ulvae and Scrobicularia plana,) in Rio San Pedro sediment fauna. In general, the results of cluster analysis showed 60% and 40% similarity in all replicated tests in El Trocadero and Rio San Pedro of sediment fauna, respectively. The results of the Principal Component Analysis (PCA) showed that both sediment parameters and pH reduction can interfere in the benthic assemblage indices. Although the assemblages' indices have shown decreases only in the lower pHs, the organisms also could be impacted by chronic effects. Therefore, the extension of this study is important in order to improve the knowledge about the risks associated with CO₂ enrichment in on marine organisms.

Effects of CO2 enrichment on metal bioavailability and bioaccumulation using Mytilus galloprovincialis

The main aim of this study was to evaluate the bioavailability of metals related to CO₂ enrichment on the mussels Mytilus galloprovincialis by metal's bioaccumulation analysis. Two sediment samples were selected and subjected to different pH levels. Concentrations of metals were measured in the overlying seawater and in the whole body of mussels exposed on the 7th, 14th and 21st days. Results showed that the CO₂ enrichment in aquatic ecosystems cause significant (p < 0.05) changes on the concentrations of Cu, Zn, Ni, Mn and As between the control pH and pH 7.0 after 7 days of exposure; and in the concentration of Fe at pH 6.0 using the RSP sediment. The multivariate analysis results showed that the increase in the bioaccumulation of some metals in mussels was linked to the acidification. It was concluded that many factors may interfere in the results when the acidification and bioavailability of metals are inquired.

Negatives and Positives: Contaminants and Other Stressors in Aquatic Ecosystems

Published research is reviewed to provide examples of both positive and negative interactions of contaminants and: climate change; habitat change; invasive and introduced species; and, eutrophication including harmful algal blooms. None of these stressor interactions results solely in negative effects. Research must shift from examining contaminants or other stressors in isolation to considering potential positive and negative effects of interactions, with the ultimate goal of providing the necessary information for the effective management of ecosystem services.