Synergistic Effects of Climate Change and Marine Pollution: An Overlooked Interaction in Coastal and Estuarine Areas

Natural distribution of pure and hybrid Mytilus sp. along the south Mediterranean and North-east Atlantic coasts and sensitivity of D-larvae stages to temperature increases and metal pollution

The distribution of the Mediterranean mussel Mytilus galloprovincialis extends more and more northwards in the Atlantic. Crossings are frequently observed with the blue mussel Mytilus edulis along the French and English coasts. The aim of this study is firstlyto identify the co-presence of M. galloprovincialis, M. edulis, and their hybrids in different sites of the Mediterranean and Atlantic coasts, and to provide insights for the thermal tolerance and toxicant susceptibility of Mytilus edulis, Mytilus galloprovincialis and their hybrids. Mussels were collected from the shore at 20 sampling sitesin Europe and Tunisia and identified using Me 15/16 primers targeting the adhesive protein gene sequence. Samples were screened for the presence of Mytilus edulis, Mytilus galloprovincialis, and hybrids alleles using PCR. To get more information on hybrids sensitivities to temperature and metals, freshly fertilized eggs of the two species and their hybrids were reared at four temperatures 18, 20, 22, and 24 °C and exposed to concentrations of Cu, Ag, and a mixture of both metals. Arrests of development and malformations were recorded after 48 h of exposure. The genotypic identification of the two species on 20 sites of the Mediterranean and Atlantic coasts carried out during this study confirms the presence of pure and hybrid species of mussel. Our results highlighted that hybrid larvae from a female of M. galloprovincialis are significantly more tolerant to temperature increases than pure larvae of M. galloprovincialis and pure and hybrid larvae of M. edulis. No significant interspecies-differences of sensitivity were noted for metal exposure alone. However, a co-exposure of larvae to both metal and high temperature highlighted the higher tolerance of hybrid larvae from a female of M. galloprovincialis to both stresses. The overall results could allow the prediction of the future evolution of mussel populations facing environmental changes.

Neurotoxicity in Marine Invertebrates: An Update

Invertebrates represent about 95% of existing species, and most of them belong to aquatic ecosystems. Marine invertebrates are found at intermediate levels of the food chain and, therefore, they play a central role in the biodiversity of ecosystems. Furthermore, these organisms have a short life cycle, easy laboratory manipulation, and high sensitivity to marine pollution and, therefore, they are considered to be optimal bioindicators for assessing detrimental chemical agents that are related to the marine environment and with potential toxicity to human health, including neurotoxicity. In general, albeit simple, the nervous system of marine invertebrates is composed of neuronal and glial cells, and it exhibits biochemical and functional similarities with the vertebrate nervous system, including humans. In recent decades, new genetic and transcriptomic technologies have made the identification of many neural genes and transcription factors homologous to those in humans possible. Neuroinflammation, oxidative stress, and altered levels of neurotransmitters are some of the aspects of neurotoxic effects that can also occur in marine invertebrate organisms. The purpose of this review is to provide an overview of major marine pollutants, such as heavy metals, pesticides, and micro and nano-plastics, with a focus on their neurotoxic effects in marine invertebrate organisms. This review could be a stimulus to bio-research towards the use of invertebrate model systems other than traditional, ethically questionable, time-consuming, and highly expensive mammalian models.

Rapid freshwater discharge on the coastal ocean as a mean of long distance spreading of an unprecedented toxic cyanobacteria bloom

Cyanobacterial toxic blooms are a worldwide problem. The Río de la Plata (RdlP) basin makes up about one fourth of South America areal surface, second only to the Amazonian. Intensive agro-industrial land use and the construction of dams have led to generalized eutrophication of main tributaries and increased the intensity and duration of cyanobacteria blooms. Here we analyse the evolution of an exceptional bloom at the low RdlP basin and Atlantic coast during the summer of 2019. A large array of biological, genetic, meteorological, oceanographic and satellite data is combined to discuss the driving mechanisms. The bloom covered the whole stripe of the RdlP estuary and the Uruguayan Atlantic coasts (around 500 km) for approximately 4 months. It was caused by the Microcystis aeruginosa complex (MAC), which produces hepatotoxins (microcystin). Extreme precipitation in the upstream regions of Uruguay and Negro rivers' basins caused high water flows and discharges. The evolution of meteorological and oceanographic conditions as well as the similarity of organisms' traits in the affected area suggest that the bloom originated in eutrophic reservoirs at the lower RdlP basin, Salto Grande in the Uruguay river, and Negro river reservoirs. High temperatures and weak Eastern winds prompted the rapid dispersion of the bloom over the freshwater plume along the RdlP northern and Atlantic coasts. The long-distance rapid drift allowed active MAC organisms to inoculate freshwater bodies from the Atlantic basin, impacting environments relevant for biodiversity conservation. Climate projections for the RdlP basin suggest an increase in precipitation and river water flux, which, in conjunction with agriculture intensification and dams' construction, might turn this extraordinary event into an ordinary situation.

Antioxidant response of the sea urchin Paracentrotus lividus to pollution and the invasive algae Lophocladia lallemandii

Pollution derived from human activities and the arrival of invasive species are common worldwide and affect coastal marine ecosystems negatively, and more especially in a semi-closed sea such as the Mediterranean Sea. The aim of the study was to evaluate oxidative stress biomarkers in the gonadal tissue of the sea urchin Paracentrotus lividus (Lamarck, 1816) sampled in different areas of Sant Antoni de Portmany (Ibiza Island, Spain) with different anthropic activities, and in an area deeply covered by the invasive red algae Lophocladia lallemandii. The densities of P. lividus were higher in the area with the greatest anthropogenic influence, while the area invaded by L. lallemandii showed the lowest density. A significant increase in the activities of the antioxidant enzymes catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) and the phase II detoxifying enzyme glutathione S-transferase (GST) was found in the most impacted area by the human activity. Moreover, malondialdehyde (MDA) and nitrite levels were also increased in the most impacted area. Similarly, the presence of L. lallemandii induced oxidative stress in P. lividus evidenced by a significant increase in all analysed biomarkers. In conclusion, changes in oxidative stress biomarkers are a good proxy to evaluate the impacts induced by anthropogenic activities and by the presence of invasive algae to P. lividus.

Morpho-Functional Alterations in the Gills of a Seawater Teleost, the Ornate Wrasse (Thalassoma pavo L.), after Short-Term Exposure to Chlorpyrifos

Chlorpyrifos (CPF) is an organophosphorus insecticide commonly used for domestic and agricultural purposes. The risk posed by environmental contamination from CPF is well acknowledged, and it has been detected worldwide in aquatic habitats and coastal areas. In addition, due to its slower degradation in seawater compared to freshwater, CPF is of particular concern for marine environments. Here, we investigated for the first time the morpho-functional alterations induced by CPF on the gills of Thalassoma pavo, a widespread species in the Mediterranean Sea. We tested the effects of two sublethal concentrations (4 and 8 µg/L) after 48 and 96 h. Our study demonstrates that the alterations induced by CPF are dose and time-dependent and highlight the harmful properties of this insecticide. After exposure to the low tested concentration, the more frequent alteration is an intense proliferation of the primary epithelium, whereas after exposure to the high concentration, the primary epithelium proliferation is less extensive, and the most evident effects are the thinning of secondary lamellae and the ectopia of chloride and goblet cells. CPF also modulated the expression of Na⁺/K⁺-ATPase. Dilation of lamellar apical tips, pillar cell degeneration, and appearance of aneurysms are often observed.

Single and combined effects of thiacloprid concentration, exposure duration, and water temperature on marbled crayfish Procambarus virginalis

The increasing utilization of chemicals and ongoing climate change have a negative impact on aquatic ecosystems. The present study examined combined effects of water temperature, chemical concentration, and duration of exposure to the neonicotinoid thiacloprid on marbled crayfish Procambarus virginalis. Crayfish were exposed to thiacloprid at the environmental concentration of 4.50 μg L-1 and 10% 96LC50 to marbled crayfish, 64.64 μg L-1, at water temperature of 17 and 23 °C for 28 days followed by a 28 day depuration period. No crayfish died during the experiment. Both thiacloprid concentrations at 23 °C showed a synergistic effect with temperature on the biochemical indicators in haemolymph compared to those at 17 °C. Both concentrations of thiacloprid at both temperatures were associated with significant differences from thiacloprid-free controls (P < 0.01) in haemolymph glucose, ammonia, calcium, inorganic phosphate, and lactate; haemolymph enzymes aspartate aminotransferase, alanine aminotransferase, creatine kinase, and alkaline phosphatase; antioxidant biomarkers superoxide dismutase, catalase, glutathione S-transferase, and reduced glutathione in hepatopancreas, muscle, and gill, and showed lipid peroxidation in hepatopancreas and muscle. Histological analyses revealed structural changes and damage to gill and hepatopancreas of exposed crayfish.

Cumulative impact assessment for ecosystem-based marine spatial planning

Claims for ocean space are growing while marine ecosystems suffer from centuries of insufficient care. Human pressures from runoff, atmospheric emissions, marine pollution, fishing, shipping, military operations and other activities wear on habitats and populations. Ecosystem-based marine spatial planning (MSP) has emerged worldwide as a strategic instrument for handling conflicting spatial claims among competing sectors and the environment. The twofold objective of both boosting the blue economy and protecting the environment is challenging in practice and marine planners need decision support. Cumulative Impact Assessment (CIA) was originally developed to provide an overview of the human imprint on the world's ocean ecosystems. We have now added a scenario component to the CIA model and used it within Swedish ecosystem-based MSP. This has allowed us to project environmental impacts for different planning alternatives throughout the planning process, strengthening the integration of environmental considerations into strategic decision-making. Every MSP decision may entail a local shift of environmental impact, causing positive or negative consequences for ecosystem components. The results from Swedish MSP in the North Sea and Baltic Sea illustrate that MSP certainly has the potential to lower net cumulative environmental impact, both locally and across sea basins, as long as environmental values are rated high and prevailing pressures derive from activities that are part of MSP. By synthesizing innumerous data into comprehensible decision support that informs marine planners of the likely environmental consequences of different options, CIA enables ecosystem-based MSP in practice.

Fluoxetine Arrests Growth of the Model Diatom Phaeodactylum tricornutum by Increasing Oxidative Stress and Altering Energetic and Lipid Metabolism

Pharmaceutical residues impose a new and emerging threat to aquatic environments and its biota. One of the most commonly prescribed pharmaceuticals is the antidepressant fluoxetine, a selective serotonin re-uptake inhibitor that has been frequently detected, in concentrations up to 40 μg L^–1, in aquatic ecosystems. The present study aims to investigate the ecotoxicity of fluoxetine at environmentally relevant concentrations (0.3, 0.6, 20, 40, and 80 μg L^–1) on cell energy and lipid metabolism, as well as oxidative stress biomarkers in the model diatom Phaeodactylum tricornutum. Exposure to higher concentrations of fluoxetine negatively affected cell density and photosynthesis through a decrease in the active PSII reaction centers. Stress response mechanisms, like β-carotene (β-car) production and antioxidant enzymes [superoxide dismutase (SOD) and ascorbate peroxidase (APX)] up-regulation were triggered, likely as a positive feedback mechanism toward formation of fluoxetine-induced reactive oxygen species. Lipid peroxidation products increased greatly at the highest fluoxetine concentration whereas no variation in the relative amounts of long chain polyunsaturated fatty acids (LC-PUFAs) was observed. However, monogalactosyldiacylglycerol-characteristic fatty acids such as C16:2 and C16:3 increased, suggesting an interaction between light harvesting pigments, lipid environment, and photosynthesis stabilization. Using a canonical multivariate analysis, it was possible to evaluate the efficiency of the application of bio-optical and biochemical techniques as potential fluoxetine exposure biomarkers in P. tricornutum. An overall classification efficiency to the different levels of fluoxetine exposure of 61.1 and 88.9% were obtained for bio-optical and fatty acids profiles, respectively, with different resolution degrees highlighting these parameters as potential efficient biomarkers. Additionally, the negative impact of this pharmaceutical molecule on the primary productivity is also evident alongside with an increase in respiratory oxygen consumption. From the ecological point of view, reduction in diatom biomass due to continued exposure to fluoxetine may severely impact estuarine and coastal trophic webs, by both a reduction in oxygen primary productivity and reduced availability of key fatty acids to the dependent heterotrophic upper levels.

Metal body burden and tissue oxidative status in the bivalve Venerupis decussata from Tunisian coastal lagoons

Coastal transitional waters are exposed to many anthropogenic threats. This study aims to assess the trace metals' pollution status of transitional waters by evaluating its biological effects in the clam Venerupis decussata. Among the studied sites along the Tunisian littoral, South Tunis and Boughrara were the most impacted, since clams from these two lagoons presented significant differences in: (i) trace metal contents, (ii) in-cell hydrogen peroxide, (iii) enzymatic and non-enzymatic defenses, (iv) damage to lipids and proteins, and (v) protein post-translational modifications. These changes related to evident histopathological traits. PCA showed a clear separation between the digestive gland and gills tissues and illustrated an impact gradient in Tunisian coastal lagoons. Water temperature was revealed as an added natural stressor that, when concurring with high pollution, may jeopardize an ecosystem's health and contribute to the accumulation of hazardous metals in organisms.

A Review of Published Literature Regarding Health Issues of Coastal Communities in Sabah, Malaysia

Several of the coastal zones in Sabah, Malaysia, are isolated and inaccessible. This study aimed to review the published literature on the health status of the coastal communities in Sabah. The following four main health issues were found: (i) malaria, (ii) tuberculosis (TB), (iii) seafood poisoning, and (iv) antenatal problems. Factors associated with the risk of acquiring malarial infection in the studied coastal area were advanced age, male sex, farming as an occupation, history of travel outside the village, and rainy seasons. TB infection was primarily observed in adult men. Seafood poisoning was significantly common in Sabah. Studies have reported that tetrodotoxin and paralytic shellfish poisoning were commonly reported (30-60 cases annually). Several pregnant women in the coastal community had insufficient knowledge of the national antenatal care programme. Nonetheless, 99% of them received antenatal care at public healthcare facilities with 92% of them undergoing safe delivery. Nevertheless, a majority of the pregnant women had iodine deficiency due to low iodised salt intake. Findings from this review highlighted that the coastal communities in Sabah are experiencing significant health problems. Specific attention is required to significantly enhance the health and well-being of the individuals living in the coastal communities in Sabah.

Energy and Exergy Evaluation of a Two-Stage Axial Vapour Compressor on the LNG Carrier

Data from a two-stage axial vapor cryogenic compressor on the dual-fuel diesel–electric (DFDE) liquefied natural gas (LNG) carrier were measured and analyzed to investigate compressor energy and exergy efficiency in real exploitation conditions. The running parameters of the two-stage compressor were collected while changing the main propeller shafts rpm. As the compressor supply of vaporized gas to the main engines increases, so does the load and rpm in propulsion electric motors, and vice versa. The results show that when the main engine load varied from 46 to 56 rpm at main propulsion shafts increased mass flow rate of vaporized LNG at a two-stage compressor has an influence on compressor performance. Compressor average energy efficiency is around 50%, while the exergy efficiency of the compressor is significantly lower in all measured ranges and on average is around 34%. The change in the ambient temperature from 0 to 50 °C also influences the compressor’s exergy efficiency. Higher exergy efficiency is achieved at lower ambient temperatures. As temperature increases, overall compressor exergy efficiency decreases by about 7% on average over the whole analyzed range. The proposed new concept of energy-saving and increasing the compressor efficiency based on pre-cooling of the compressor second stage is also analyzed. The temperature at the second stage was varied in the range from 0 to −50 °C, which results in power savings up to 26 kW for optimal running regimes.