Posts Tagged 'pollution'

Cumulative human impacts on Mediterranean and Black Sea marine ecosystems: assessing current pressures and opportunities

Management of marine ecosystems requires spatial information on current impacts. In several marine regions, including the Mediterranean and Black Sea, legal mandates and agreements to implement ecosystem-based management and spatial plans provide new opportunities to balance uses and protection of marine ecosystems. Analyses of the intensity and distribution of cumulative impacts of human activities directly connected to the ecological goals of these policy efforts are critically needed. Quantification and mapping of the cumulative impact of 22 drivers to 17 marine ecosystems reveals that 20% of the entire basin and 60–99% of the territorial waters of EU member states are heavily impacted, with high human impact occurring in all ecoregions and territorial waters. Less than 1% of these regions are relatively unaffected. This high impact results from multiple drivers, rather than one individual use or stressor, with climatic drivers (increasing temperature and UV, and acidification), demersal fishing, ship traffic, and, in coastal areas, pollution from land accounting for a majority of cumulative impacts. These results show that coordinated management of key areas and activities could significantly improve the condition of these marine ecosystems.

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Combined effects of two emerging environmental stressors (perfluorooctane sulfonate and carbon dioxide) on estrogenic responses of juvenile Atlantic cod (Gadus morhua)

Predicted climate changes have been suggested to alter future distribution and toxicity of persistent organic pollutants (POPs). Until now, little effort has been put into investigating such interactive effects between POPs and elevated CO2 levels (hypercapnia) in the aquatic environment. In the present study, juvenile Atlantic cod (Gadus morhua) were exposed to the emerging POP perfluorooctane sulfonate (PFOS; 0, 100 and 200 µg/L) for 1 hour/day in 5 days, followed by changes in elevated water CO2 saturation (0, 0.3 and 0.9%) for 3, 6 and 9 days. Endocrine disrupting potential of PFOS and elevated CO2 levels, both singly and in combination, were examined by analyzing levels of sex steroid hormones (E2, T, 11-KT) and transcript expression of estrogen responsive genes (ER-α, Vtg-α, Vtg-β, ZP-2, ZP-3), in addition to steroid and xenobiotic metabolism (CYP1A, CYP3A) and hypoxia-inducible factor (HIF-1α). Elevated CO2 produced increased levels of sex steroid hormones (E2, T, 11-KT) with concomitant increases in transcriptional expression of estrogen responsive genes. PFOS produced a weak time- and dose-dependent estrogenic effect as measured in mRNA expression of estrogen responsive genes, but no effect on steroid hormone levels. Exposure to elevated CO2 and PFOS in combination produced gene expression patterns that are different from the effects observed for CO2 and PFOS alone, indicating interactive effects. These observations suggest that hypercapnia and emerging POPs such as PFOS in combination could modulate the estrogen signaling in juvenile Atlantic cod (Gadus morhua), with potential consequences for sexual development and reproduction. To the best of our knowledge, this is the first study to report hypercapnia-induced sex steroid disruption in any fish species or lower vertebrate. These findings suggest a potential for adverse effects of increased anthropogenic CO2 emissions on sexual development and reproduction in fish. This also raises the question whether such interactive effects might be observed in other aquatic species and with other endocrine disrupters and POPs as well. Such findings could have implications for the accuracy of current risk assessments of emerging POPs, under changing climatic conditions.

Continue reading ‘Combined effects of two emerging environmental stressors (perfluorooctane sulfonate and carbon dioxide) on estrogenic responses of juvenile Atlantic cod (Gadus morhua)’

Chapter five – stress biology and immunology in Nephrops norvegicus

The Norway lobster Nephrops norvegicus lives at low-light depths, in muddy substrata of high organic content where water salinities are high and fluctuations in temperature are moderate. In this environment, the lobsters are naturally exposed to a number of potential stressors, many of them as a result of the surficial breakdown of organic material in the sediment. This process (early diagenesis) creates a heterogeneous environment with temporal and spatial fluctuations in a number of compounds such as oxygen, ammonia, metals, and hydrogen sulphide. In addition to this, there are anthropogenically generated stressors, such as human-induced climate change (resulting in elevated temperature and ocean acidification), pollution and fishing. The lobsters are thus exposed to several stressors, which are strongly linked to the habitat in which the animals live. Here, the capacity of Nephrops to deal with these stressors is summarised. Eutrophication-induced hypoxia and subsequent metal remobilisation from the sediment is a well-documented effect found in some wild Nephrops populations. Compared to many other crustacean species, Nephrops is well adapted to tolerate periods of hypoxia, but prolonged or severe hypoxia, beyond their tolerance level, is common in some areas. When the oxygen concentration in the environment decreases, the bioavailability of redox-sensitive metals such as manganese increases. Manganese is an essential metal, which, taken up in excess, has a toxic effect on several internal systems such as chemosensitivity, nerve transmission and immune defence. Since sediment contains high concentrations of metals in comparison to sea water, lobsters may accumulate both essential and non-essential metals. Different metals have different target tissues, though the hepatopancreas, in general, accumulates high concentrations of most metals. The future scenario of increasing anthropogenic influences on Nephrops habitats may have adverse effects on the fitness of the animals.

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Interactive effects of global climate change and pollution on marine microbes: the way ahead

Global climate change has the potential to seriously and adversely affect marine ecosystem functioning. Numerous experimental and modeling studies have demonstrated how predicted ocean acidification and increased ultraviolet radiation (UVR) can affect marine microbes. However, researchers have largely ignored interactions between ocean acidification, increased UVR and anthropogenic pollutants in marine environments. Such interactions can alter chemical speciation and the bioavailability of several organic and inorganic pollutants with potentially deleterious effects, such as modifying microbial-mediated detoxification processes. Microbes mediate major biogeochemical cycles, providing fundamental ecosystems services such as environmental detoxification and recovery. It is, therefore, important that we understand how predicted changes to oceanic pH, UVR, and temperature will affect microbial pollutant detoxification processes in marine ecosystems. The intrinsic characteristics of microbes, such as their short generation time, small size, and functional role in biogeochemical cycles combined with recent advances in molecular techniques (e.g., metagenomics and metatranscriptomics) make microbes excellent models to evaluate the consequences of various climate change scenarios on detoxification processes in marine ecosystems. In this review, we highlight the importance of microbial microcosm experiments, coupled with high-resolution molecular biology techniques, to provide a critical experimental framework to start understanding how climate change, anthropogenic pollution, and microbiological interactions may affect marine ecosystems in the future.

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