Estuaries

Quantifying the relationship between mesozooplankton and water quality parameters identifies the factors that structure the mesozooplankton community and can be used to generate hypotheses regarding the mechanisms that control the mesozooplankton population and potentially the trophic network. To investigate this relationship, mesozooplankton and water quality data were collected in Florida Bay from 1994 to 2004. Three key characteristics were found in the mesozooplankton community structure: (1) there are significant differences between the four sub-regions of Florida Bay; (2) there is a break in May of 1997 with significant differences before and after this date; and (3) there is a positive correlation between mesozooplankton abundance and salinity. The latter two characteristics are closely correlated with predator abundance, indicating the importance of top-down control. Hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance despite the increased physiological stress.

India is rich of enormous bounding coastline and vast stretches of estuaries and backwaters. Indian estuaries and coastal waters have numbers of classic research records, most of which are historically important. However, the belated development of estuarine ecology as a field of systematic research has been the outcome of growing concern about immense societal importance of these ecosystems. The varied and increasingly complex problems created through man-made and also natural process have been instrumental in rapid depletion of estuarine resources of the India. Due to obvious reasons, the estuaries need to have focused attention on the issues like status evaluation and stress quantification of the individual system for conservation and protection against further deterioration in future. Available accounts of estuarine biology and fisheries mostly pinpoint limited aspects as intended for. A few research results have comprehensive information and utility for exploring time scale scenario and trend analysis. The book has been designed to bridge and logically interpret the research findings of galaxy of scientists and also the authors, and put forward the management norms for eco-environmental conservation and production sustenance of the estuarine resources.

This report outlines the results of the academic research on historical evolution of the Ems-Dollard estuary. We analyzed the channel-bar patterns and changes in channel volume over the last 200 years and the role of resistant layers in the estuary’s substrate. For this, historical bathymetry was derived from historical maps and a new map with position of resistant layers in the substrate of the estuary was compiled. Holocene clays and peats are resistant layers that locally delay morphological development and form scour holes in the channel bed. Pleistocene resistant layers are more resistant and affect the entire estuary. They limit channel depth and consequently cause widening, resulting in mid-channel bar formation and increased channel curvature. Furthermore, deeper channel confluences preferentially form where resistant layers were absent. The combined effects force the position and dimensions of confluences and bars. Where future sea-level rise may cause channel volumes to increase, antecedent geology will be more exposed, which could lead to unexpected changes in the channel pattern. Based on the demonstrated importance of resistant layers in the past, we recommend to account for them in the likely response of estuaries to sea-level rise. Resistant layer maps could be further improved, when more geological data is incorporated around the watershed between the Eastern and Western Ems.
Over the last two centuries, channel volumes (below NAP ~MSL) have decreased by 1 to 4.6 Mm3 /yr on average, this trend was interrupted in the 1960ies and 1970ies when sediment was extracted from the system. Gas-extraction induced subsidence and especially sea-level rise will cause morphological changes the coming century. Assuming that channel and shoal morphology do not change, 1.5 to 5.3 Mm3/yr of sediment would be needed (for 0.25 and 1.2 m respectively sea-level rise in 2100). Although this is in the same order of magnitude as natural sediment import in the channels over the last two centuries, it is unknown whether the sediments can be provided. Because the estuary needs sediment, sand extraction can best be avoided. Stimulating saltmarsh growth, as has been done in the past, could help flood protection and at the same time reduce suspended sediment concentrations. We recommend to study the effect of this measure on the shoals and channels.

Chemical contaminants can be introduced into estuarine and marine ecosystems from a variety of sources including wastewater, agriculture and forestry practices, point and non-point discharges, runoff from industrial, municipal, and urban lands, accidental spills, and atmospheric deposition. The diversity of potential sources contributes to the likelihood of contaminated marine waters and sediments and increases the probability of uptake by marine organisms. Despite widespread recognition of direct and indirect pathways for contaminant deposition and organismal exposure in coastal systems, spatial and temporal variability in contaminant composition, deposition, and uptake patterns are still poorly known. We investigated these patterns for a suite of persistent legacy contaminants including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) and chemicals of emerging concern including pharmaceuticals within two Oregon coastal estuaries (Coos and Netarts Bays). ...

This memo is the result of an exploration of possible sources on the Eastern Scheldt estuary. The memo’s aim is to provide a clear point of departure for the Eastern Scheldt Survey, which will summarize up to date knowledge on the Eastern Scheldt Barrier and its effects.
It offers the opportunity for the Severe Storm Prediction Education and Evacuation from Disasters-center (SSPEED), the commissioner of the Survey, to give further direction to the search if required.
Being the product of much public and expert debate, the barrier and the estuary have enjoyed much attention over the last decades, resulting in numerous publications addressing a variety of topics. The findings of the exploration of these sources are grouped in three categories: (1) decision-making regarding the construction of the barrier, (2) the environmental effects, and (3) the effect on the regional spatial-economic development pattern. Within these categories, the following themes were studied:
i. Public and expert debate before, during and after construction (and its effect on policy and decision-making)
ii. Effects on hydrodynamics, sediment fluxes and morphology
iii. Effects on benthos and primary production
iv. Effects on wading birds
v. Mitigation measures
vi. Economy
vii. Land use development pattern

Environmental indicators must have a predictable relationship with stressors to be of value in ecological assessments. We evaluated the information provided by commonly implemented monitoring indicators as a means of assessing of the level of ecological impact experienced by coastal lagoons in New South Wales, Australia. Existing data for environmental variables in coastal lagoons were correlated with independent estimates of catchment disturbance. There were few relationships between the monitoring variables (particularly water chemistry) and nutrient loads and catchment land use. Data from NSW catchments and lagoons were compared to analogous data from published northern hemisphere studies and it was clear that stressor variables were up to one to two orders of magnitude smaller in NSW, potentially explaining the lack of relationships with recognised indicators.Our study has highlighted the importance of using a range of indicators to assess trends in ecological condition of an estuarine ecosystem, particularly where stressor levels are not great. Using water quality as the sole means of determining lagoon condition was simply inadequate in NSW lagoons. We recommended that ecological outcome indicators such as algal abundance (macro and micro) and turbidity were most likely to show interpretable patterns at low to moderate nitrogen loadings (<40 kg Ha−1 yr−1) and that these should form the basis of estuarine trend monitoring in NSW lagoons. The demonstrated value of seagrass and macroalgal monitoring in estuaries with moderate to high nutrient loadings suggests that these indicators should not be overlooked when planning monitoring programs, recognising, however, they will not have strong discrimination at lower catchment loadings.

This study was originally submitted as a dissertation for the doctoral degree in Marine Sciences for the Department of Marine Sciences of the University of Puerto Rico at Mayagüez. It was subdivided into eleven chapters and two appendixes, which treated a number of biological aspects of the coastal, marine, and estuarine mycology of the Puerto Rican archipelago.  Field and laboratory surveys were carried out.  It has been summarized the history of marine mycology in Puerto Rico, a checklist of all the known fungi species, and general ecological aspects in beaches, mangroves, and estuarine environments.  Some fungal species might be useful for bioremediation.  For example, two species of Cladosporium were isolated from seawater based on their ability to use the polyaromatic hydrocarbons naphthalene and phenanthrene as a sole carbon and energy source.  Also a bibliography on coastal and marine biology primarily mycological in orientation is presented.

Long-term assessment of ecosystem restoration projects is complex because of ecological processes such as succession, particularly in highly dynamic ecosystems such as estuaries. Restoration of intertidal flats and marshes on formerly embanked land, often called managed coastal realignment (MR), became popular in estuarine management. In our study, biophysical and monetary data were collected to calculate the value of 15 (sub)ecosystem services (ES) delivered by a large tidal marsh restoration project in the Schelde estuary in Belgium and the Netherlands. We hypothesized that ES delivery changes over time due to ecological succession and hence the long-term benefits are subject to this phenomenon and need to be taken into consideration. A marsh sediment accretion model (MARSED) was used to simulate potential marsh succession scenarios. In this way, the temporal evolution of ES delivery caused by ecological succession could be evaluated. Our study shows that benefits during successional marsh stages could actually be higher than for marshes in equilibrium. This finding does not suggest that ecosystems in transition always have a higher value than systems in equilibrium, but emphasizes the need to consider long-term ecological dynamics, such as succession, in a benefit assessment for restoration projects.