Estuaries are among the ecosystems most affected by human actions worldwide. Economic development in Morocco puts pressure on these aquatic systems, making them vulnerable. This study compares the ...state of benthic communities between a pristine estuary (Massa estuary) and a polluted one (Souss estuary). Both ecosystems belong to the Souss Massa National Park (SMNP), registered in the Ramsar list for its ecological importance as a Marine Protected Area (MPA). Twenty-one benthic species were identified in the pristine estuary, but only six species in the polluted one. Similar differences were detected for the species abundance and biomass. The total organic matter and the water-dissolved oxygen also revealed a notable negative effect of the sewage discharge. The results confirmed human disturbances on faunal communities related to direct wastewater inputs and indirect anthropogenic activities such as the urbanization and the litter generation. A combination of ending wastewater discharge and adding tertiary-level water treatment plants is recommended. The findings highlight the importance of MPAs in conservation strategies if coupled with continuous surveillance of pollution.
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•Study of benthic communities in two estuaries of a marine protected area (MPA) in Morocco•Significant difference found between pristine and polluted estuaries•Wastewater inputs influenced the load of organic matter and the dissolved oxygen.•Urgent addition/upgrading to tertiary-level water treatment plants and ending wastewater discharge is needed.•MPAs are effective if coupled with continuous surveillance of pollution.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Kelps are ecologically important primary producers and ecosystem engineers, and play a central role in structuring nearshore temperate habitats. They play an important role in nutrient cycling, ...energy capture and transfer, and provide biogenic coastal defence. Kelps also provide extensive substrata for colonising organisms, ameliorate conditions for understorey assemblages, and provide three-dimensional habitat structure for a vast array of marine plants and animals, including a number of commercially important species. Here, we review and synthesize existing knowledge on the functioning of kelp species as biogenic habitat providers. We examine biodiversity patterns associated with kelp holdfasts, stipes and blades, as well as the wider understorey habitat, and search for generality between kelp species and biogeographic regions. Environmental factors influencing biogenic habitat provision and the structure of associated assemblages are considered, as are current threats to kelp-dominated ecosystems. Despite considerable variability between species and regions, kelps are key habitat-forming species that support elevated levels of biodiversity, diverse and abundant assemblages and facilitate trophic linkages. Enhanced appreciation and better management of kelp forests are vital for ensuring sustainability of ecological goods and services derived from temperate marine ecosystems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Herbivory and nutrient availability are fundamental drivers of benthic community succession in shallow marine systems, including coral reefs. Despite the importance of early community succession for ...coral recruitment and recovery, studies characterizing the impact of top-down and bottom-up drivers on micro- and macrobenthic communities at scales relevant to coral recruitment are lacking. Here, a combination of tank and field experiments were used to assess the effects of herbivore exclusion and nutrient enrichment on micro- to macrobenthic community succession and subsequent coral recruitment success. Herbivore exclusion had the strongest effect on micro- and macrobenthic community succession, including a community shift toward copiotrophic and potentially opportunistic/pathogenic microorganisms, an increased cover of turf and macroalgae, and decreased cover of crustose coralline algae. Yet, when corals settled prior to the development of a macrobenthic community, rates of post-settlement survival increased when herbivores were excluded, benefiting from the predation refugia provided by cages during their vulnerable early post-settlement stage. Interestingly, survival on open tiles was negatively correlated with the relative abundance of the bacterial order Rhodobacterales, an opportunistic microbial group previously associated with stressed and diseased corals. Development of micro- and macrobenthic communities in the absence of herbivory, however, led to reduced coral settlement. In turn, there were no differences in post-settlement survival between open and caged treatments for corals settled on tiles with established benthic communities. As a result, open tiles experienced marginally higher recruitment rates, driven primarily by the higher initial number of settlers on open tiles compared to caged tiles. Overall, we reveal that the primary interaction driving coral recruitment is the positive effect of herbivory in creating crustose coralline algae (CCA)-dominated habitats, free of fleshy algae and associated opportunistic microbes, to enhance coral settlement. The negative direct and indirect impact of fish predation on newly settled corals was outweighed by the positive effect of herbivory on the initial rate of coral settlement. In turn, the addition of nutrients further altered benthic community succession in the absence of herbivory, reducing coral post-settlement survival. However, the overall impact of nutrients on coral recruitment dynamics was minor relative to herbivory.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Application of sidescan sonar at the regional scale of the Abrolhos Bank, with ground-truthing by remotely operated vehicles and mixed-gas diving operations, revealed a much more complex habitat ...mosaic than previously recognized. The regional benthic habitat map indicates 8844km2 of reefs (earlier estimates from remote sensing were around 500km2) and 20,904km² of rhodolith habitat—the world's largest continuous bed. Integration of the regional megahabitat map with spatially explicit data on the distribution of marine protected areas (<0.2% of each benthic megahabitat area) and economic activities with the highest potential of environmental impact (fishing, mining, oil and gas exploitation and dredging) reveals the need of a regional scale spatial planning process engaging conflicting sectors.
•We present a benthic megahabitat map for the Abrolhos Shelf, with three megahabitats.•Benthic megahabitats include 8844km2 of reefs and the world's largest rhodolith bed with 20,904km².•Primary and secondary databases on the main economic activities and marine protected areas were integrated in the analyses.•Marine protected areas coverage is incipient and covers less than 0.5% of each megahabitat.•Elements for triggering spatial planning at the regional scale are presented and discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Accelerated exploration of minerals in the deep sea over the past decade has raised the likelihood that commercial mining of the deep seabed will commence in the near future. Environmental concerns ...create a growing urgency for development of environmental regulations under commercial exploitation. Here, we consider an ecosystem services approach to the environmental policy and management of deep-sea mineral resources. Ecosystem services link the environment and human well-being, and can help improve sustainability and stewardship of the deep sea by providing a quantitative basis for decision-making. This paper briefly reviews ecosystem services provided by habitats targeted for deep-seabed mining (hydrothermal vents, seamounts, nodule provinces, and phosphate-rich margins), and presents practical steps to incorporate ecosystem services into deep-seabed mining regulation. The linkages and translation between ecosystem structure, ecological function (including supporting services), and ecosystem services are highlighted as generating human benefits. We consider criteria for identifying which ecosystem services are vulnerable to potential mining impacts, the role of ecological functions in providing ecosystem services, development of ecosystem service indicators, valuation of ecosystem services, and implementation of ecosystem services concepts. The first three steps put ecosystem services into a deep-seabed mining context; the last two steps help to incorporate ecosystem services into a management and decision-making framework. Phases of environmental planning discussed in the context of ecosystem services include conducting strategic environmental assessments, collecting baseline data, monitoring, establishing marine protected areas, assessing cumulative impacts, identifying thresholds and triggers, and creating an environmental damage compensation regime. We also identify knowledge gaps that need to be addressed in order to operationalize ecosystem services concepts in deep-seabed mining regulation and propose potential tools to fill them.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Parasite–host systems are pervasive in nature but are extremely difficult to convincingly identify in the fossil record. Here we report quantitative evidence of parasitism in the form of a ...unique, enduring life association between tube-dwelling organisms encrusted to densely clustered shells of a monospecific organophosphatic brachiopod assemblage from the lower Cambrian (Stage 4) of South China. Brachiopods with encrusting tubes have decreased biomass (indicating reduced fitness) compared to individuals without tubes. The encrusting tubes orient tightly in vectors matching the laminar feeding currents of the host, suggesting kleptoparasitism. With no convincing parasite–host interactions known from the Ediacaran, this widespread sessile association reveals intimate parasite–host animal systems arose in early Cambrian benthic communities and their emergence may have played a key role in driving the evolutionary and ecological innovations associated with the Cambrian radiation.
Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds, found ubiquitously in all environmental compartments. PAHs are considered hazardous pollutants, being of concern to both the ...environmental and human health. In the aquatic environment, PAHs tend to accumulate in the sediment due to their high hydrophobicity, and thus sediments can be considered their ultimate sink. Concurrently, sediments comprise important habitats for benthic species. This raises concern over the toxic effects of PAHs to benthic communities. Despite PAHs have been the subject of several reviews, their toxicity to freshwater benthic species has not been comprehensively discussed. This review aimed to provide an overview on PAHs distribution in freshwater environments and on their toxicity to benthic fauna species. The distribution of PAHs between sediments and the overlying water column, given by the sediment-water partition coefficient, revealed that PAHs concentrations were 2 to 4 orders of magnitude higher in sediments than in water. The sediment-water partition coefficient was positively correlated to PAHs hydrophobicity. Toxicity of PAHs to benthic fauna was addressed through Species Sensitivity Distributions. The derived hazardous concentration for 5% of the species (HC5) decreased as follows: NAP (376 μg L−1) > PHE > PYR > FLT > ANT (0.854 μg L−1), varying by 3 orders of magnitude. The hazardous concentrations (HC5) to benthic species were inversely correlated to the hydrophobicity of the individual PAHs. These findings are pertinent for environmental risk assessment of these compounds. This review also identified future challenges regarding the environmental toxicity of PAHs to freshwater benthic communities, namely the need for updating the PAHs priority list and the importance of comprehensively and more realistically assess the toxicity of PAHs in combination with other stressors, both chemical and climate-related.
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•PAHs concentrations were 2–4 orders of magnitude higher in sediments than in water.•PAHs sediment-water partitioning coefficients increased along with hydrophobicity.•Hazardous concentrations decreased with increasing hydrophobicity.•HC5 values for benthic communities were ranked as NAP > PHE > PYR > FLT > ANT.•These findings are pertinent for ecological risk assessment of PAHs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The seafloor of the eastern Gulf of Finland (the Baltic Sea), especially its easternmost part – Neva Bay – has experienced anthropogenic impacts since the beginning of the XVIII century. The aim of ...this paper is: i) to analyze results of different stages of anthropogenic impact on the geological environment and ecosystem, ii) to assess the influence of dredging, dumping, and aggregates (sand, gravel) and ferromanganese concretions extraction on bottom relief and sedimentation processes, and iii) to establish the major spatial and temporal trends of heavy metal accumulation in the soft bottom sediments. Since the establishment of St. Petersburg, and into the 1960s, there was a physical impact on the seabed through the construction of artificial islands, dredging, and dumping. From 1960s to the 1990s, these types of activity became even more intense, as nearshore submarine terraces were used for sand and gravel extraction, and sediment pollution (e.g., heavy metals) has become one of the main environmental problems of the region. Based on extensive geochemical data collected for the first time in the study area, we examined a vertical distribution of heavy metals in cores obtained from different sedimentary basins. Results demonstrate a trend of increasing concentration values from the 1940s to the 1990s. Background concentrations of heavy metals are based on the geochemistry of catchment areas, decreasing in concentrations from the northwest to the southeast, while the maximum concentrations of hazardous substances deposited from the 1970s to the 1990s were observed in the easternmost part of the gulf. Since the 1990s the heavy metal input to the Gulf of Finland has significantly decreased, so the concentration of these hazardous substances in the surface sediments dropped as well, demonstrating a spatial distribution corresponding more to background (natural, pre-industrial) values. On the other hand, big hydrotechnical projects, realized during the last 20 years – artificial territories and new harbors construction, accompanying with dredging and dumping, ferromanganese concretion extraction, etc. – led to resuspension and secondary pollution of water. The other problem is the expansion of anoxic areas, caused both by climate change and human-stimulated eutrophication. Near-bottom anoxic conditions stimulate heavy metal migration from bottom sediments into the water column. All these processes impacted benthic communities as our review of previously published studies reveals. Geological and geophysical research revealed that within some areas anthropogenic impact caused a complete change of the sedimentation processes such as direction and rates of transport, which led to the total transformation of bottom relief, surface sediment distribution, and the benthic communities.
•The eastern Gulf of Finland is one of the most highly impacted area of the Baltic Sea.•Physical impact on the sea bottom (dredging, dumping, sand and gravel extraction etc.) have a strong negative effect on benthic communities.•Heavy metal content in the bottom sediments indicate the amount of hazardous substances input to the Gulf of Finland. Vertical distribution of heavy metals in the cores demonstrates trends of increasing concentration values since 1940s–1990s, and an opposite trend ever since.•Expanding of hypoxic/anoxic near-bottom conditions caused by climate change and anthropogenic nutrient load factors is a significant environmental health problem in the Gulf of Finland. The invasion and mass expansion of the hypoxic-tolerant polychaete Marenzelleria arctia can mitigate the negative effects of oxygen depletion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Ecosystem macroscopic properties given by
Ascendency
theoretical framework were compared between two multispecies mass-balanced trophic models of the coastal benthic ecosystem along Mejillones Bay in ...northern Chile (SE Pacific). The models were constructed with a similar number of components representing system conditions for years 2006 and 2018 using
Ecopath with Ecosim
(EwE) software. The most relevant change was that the macroalgae (principally Rhodophyta group) increased notably over 12 years. In terms of
Ascendency
, the larger increase in
Total System Throughput
(TST) compared to the null increment in the
Average Mutual Information
would indicate that the benthic ecosystem of Mejillones Bay is moving towards eutrophic conditions. This is consistent with the reduction in the TST cycled,
Finn’s cycling index
, and a two-fold increase in the flow of detritus. Likewise, the
Keystone Species Complex
seems to be sensitive to changes in the properties of ecosystems, reducing the number of components in cases of deteriorated ecosystem. Based on the results obtained, it is suggested the implementation of management strategies that allow reversing this trend towards eutrophication, such as, to strengthen environmental policies and monitoring programs in order to conserve the benthic communities of Mejillones Bay.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study was to describe the epibenthic and demersal communities of the Avilés Canyon System (ACS) in relation to the environmental variables that characterize their biotope. ACS ...(Cantabrian Sea, NE Atlantic) was recently included in the Natura 2000 network as a Site of Community Importance (SCI). Data of faunal biomass derived from 6 surveys carried out using beam trawl and otter trawls in 2009 and 2010 within INDEMARES and ERDEM projects. Data were divided into two groups to obtain information about the two ecological compartments: benthic and demersal. The total number of species used in this analysis ascended to 116 in the case of benthic organisms and 110 in the case of demersal. Hierarchical clustering analysis was applied to obtain groups of samples similar in terms of species composition for the two ecological components. Depth was the main discriminating factor for grouping hauls, showing high consistency of bathymetric range independently from the compartment examined. Six groups were identified by depth as follows: medium shelf (∼100–200 m), external shelf (∼150–300m), shelf break (∼300–400 m), upper-slope (∼500–700 m), upper middle-slope (∼700–1100 m), and lower-middle-slope (1200–1500 m). SIMPER analysis on biomass values was performed to determine the structure of the faunal assemblages observed for each group in both compartments. Using biomass values for the analysis allowed for the exploration of groups playing important roles in ecosystem functioning and energy fluxes taking place on the sedimentary bottom of this SCI. Finally, CCA analysis revealed that the main environmental drivers were depth, broad scale bathymetric position index (BPI), near-bottom salinity, sedimentary type, and dynamics related variables (Q50 phy and So). This study gives an inventory of the soft bottom assemblages along a very wide depth range (100–1500 m) inside a SCI, linking both epibenthic and demersal communities with the biotope preferences. This study contributes to fundamental knowledge on soft-bottom communities as a pre-requisite, necessary for the next steps in terms of management framework in the SCI.
•Data of bottom related fauna in a marine SCI were analysed in North of Spain.•Soft bottom communities of the Avilés Canyon System were determined.•Epibenthic and demersal assemblages described followed a bathymetric pattern.•Environmental linkages were observed related with physics and geological factors.•BPI broad, Salinity, Bottom type and sedimentary dynamics influence assemblages.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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