Relationships Between Benthic Infauna and Groundwater Eutrophication On A Sandy Beach in Southern Brazil

Urban expansion in Brazilian coastal zones has caused various anthropic impacts on coastal marine ecosystems that have resulted from unorganized use and the lack of infrastructure projects. The inadequate disposal of domestic and industrial effluents in coastal waterbodies is notable, which can cause severe environmental problems. For sandy beaches, the relationships between the contamination of groundwater with domestic sewage and the possible effects on spatial and temporal variations in the density and composition of benthic infauna are still poorly understood. This work aimed to relate variations in benthic infaunal associations with the concentrations of groundwater nutrients in summer and winter on Enseada Beach. The greater concentrations of nutrients in water percolating through the sediment in the summer, increasing of domestic effluents, and periods of intense precipitation increased the contamination of the surface and groundwater. This contributes to an increase in the population density of Thoracophelia furcifera, demonstrating its use as an indicator of eutrophication of the groundwater, allowing monitoring and contribution to actions aimed at improving the environmental quality of sandy beaches.

Missing the Forest and the Trees: Utility, Limits and Caveats for Drone Imaging of Coastal Marine Ecosystems

Coastal marine ecosystems are under stress, yet actionable information about the cumulative effects of human impacts has eluded ecologists. Habitat-forming seaweeds in temperate regions provide myriad irreplaceable ecosystem services, but they are increasingly at risk of local and regional extinction from extreme climatic events and the cumulative impacts of land-use change and extractive activities. Informing appropriate management strategies to reduce the impacts of stressors requires comprehensive knowledge of species diversity, abundance and distributions. Remote sensing undoubtedly provides answers, but collecting imagery at appropriate resolution and spatial extent, and then accurately and precisely validating these datasets is not straightforward. Comprehensive and long-running monitoring of rocky reefs exist globally but are often limited to a small subset of reef platforms readily accessible to in-situ studies. Key vulnerable habitat-forming seaweeds are often not well-assessed by traditional in-situ methods, nor are they well-captured by passive remote sensing by satellites. Here we describe the utility of drone-based methods for monitoring and detecting key rocky intertidal habitat types, the limitations and caveats of these methods, and suggest a standardised workflow for achieving consistent results that will fulfil the needs of managers for conservation efforts.

Trace metals accumulation on the Po river prodelta, North Adriatic Sea

<p><span>The Po River delta (northern Italy) is a complex system composed of terrestrial, transitional and coastal-marine ecosystems strongly influenced by different natural and anthropogenic stressors. In this study, we aimed to provide the anthropic impact during the last 200 years through geochemical concentration of heavy metals. In order to reach this objective, trace Metals (TMs: Pb, Zn, Cu, Cr, Cd and Ni), major elements (Al, Fe and Mn) and natural/artificial radionuclides (210Pb/137Cs) were analysed on the sediment core (EL14-C01) collected in 2014 in the Po River prodelta. We assumed the TMs mean concentrations during the pre-industrial time (before 1850) as the natural background in this area. Sediments deposited after 1850 exhibited a TMs gradual rise compared to the concentrations recorded in the pre-industrial era, in particular Pb, Zn and Cu (PZC). PZC vertical profiles show that the contamination has increased dramatically after the Second World War, during the so called ‘‘Italian Economic Miracle’’ period, exceeding up to 2.5, 2 and 1.5 (Pb>Zn>Cu) times the concentrations of the pre-industrial era. Post-war years saw the birth of the mechanical, chemical, ceramics Italian industries, and the switch from coal to oil and the plastic derivatives it entailed (Romano et al. 2013). The PZC concentrations reached the maximum between 1970s and 1980s, in agreement with anthropogenic atmospheric emissions changes. The distributions of ZPC indicate a sharp contamination decrease from the second half of the 1980s. Probably this reduction was related to the introduction of the Italian Law 319/76 and to the implementation of anti-pollution policies on automotive Pb (unleaded fuels). Recently, the levels of anthropogenic ZPC pollution are similar to the pre-WWII values. During the XXth century, the geochemical analysis show some TMs/Al peaks corresponding to the seven major Po floods with discharges above 8000 m3/s occurred in 1917, 1926, 1928, 1951, 1976, 1994, and 2000.</span></p><p align="justify"><br><br></p>

Potentially bioavailable iron produced through benthic cycling in glaciated Arctic fjords of Svalbard

The Arctic has the highest warming rates on Earth. Glaciated fjord ecosystems, which are hotspots of carbon cycling and burial, are extremely sensitive to this warming. Glaciers are important for the transport of iron from land to sea and supply this essential nutrient to phytoplankton in high-latitude marine ecosystems. However, up to 95% of the glacially-sourced iron settles to sediments close to the glacial source. Our data show that while 0.6–12% of the total glacially-sourced iron is potentially bioavailable, biogeochemical cycling in Arctic fjord sediments converts the glacially-derived iron into more labile phases, generating up to a 9-fold increase in the amount of potentially bioavailable iron. Arctic fjord sediments are thus an important source of potentially bioavailable iron. However, our data suggests that as glaciers retreat onto land the flux of iron to the sediment-water interface may be reduced. Glacial retreat therefore likely impacts iron cycling in coastal marine ecosystems.

Role of external inputs of nutrients to aquatic ecosystems in determining prevalence of nitrogen vs. phosphorus limitation of net primary productivity

Whether net primary productivity in an aquatic ecosystem is limited by nitrogen (N), limited by phosphorus (P), or co-limited by N & P is determined by the relative supply of N and P to phytoplankton compared to their elemental requirements for primary production, often characterized by the “Redfield” ratio. The supply of these essential nutrients is affected by both external inputs and biogeochemical processes within the ecosystem. In this paper, we examine external sources of nutrients to aquatic systems and how the balance of N to P inputs influences nutrient limitation. For ocean subtropical gyres, a relatively balanced input of N and P relative to the Redfield ratio from deep ocean sources often leads to near co-limitation by N and P. For lakes, the external nutrient inputs come largely from watershed sources, and we demonstrate that on average the N:P ratio for these inputs across the United States is well above that needed by phytoplankton, which may contribute to P limitation in those lake that experience this average nutrient loading. Watershed inputs are also important for estuaries and coastal marine ecosystems, but ocean sources of nutrients are also significant contributors to overall nutrient loads. The ocean-nutrient sources of N and P are very often at or below the Redfield ratio of 16:1 molar, and can be substantially so, particularly in areas where the continental shelf is wide. This large input of coastal ocean nutrients with a low N:P ratio is one factor that may make N limitation more likely in many coastal marine ecosystems than in lakes.