Estuaries

South Florida's watersheds have endured a century of urban and agricultural development and disruption of their hydrology. Spatial characterization of South Florida's estuarine and coastal waters is important to Everglades' restoration programs. We applied Factor Analysis and Hierarchical Clustering of water quality data in tandem to characterize and spatially subdivide South Florida's coastal and estuarine waters. Segmentation rendered forty-four biogeochemically distinct water bodies whose spatial distribution is closely linked to geomorphology, circulation, benthic community pattern, and to water management. This segmentation has been adopted with minor changes by federal and state environmental agencies to derive numeric nutrient criteria.

To enable a relevant interpretation of otolith strontium : calcium (Sr/Ca) variations in terms of habitat shifts of eels, the Sr/Ca-salinity relationship in eel otoliths was validated. Downstream and upstream migrations of young eels were reproduced in the laboratory by transferring groups of fish every 2 months between aquaria filled with water coming from the Dordogne river (salinity = 0), the upper Gironde estuary (salinity = 5), the lower Gironde estuary (salinity = 25) and the coast (salinity = 30), which represented the salinity gradient observed in the Gironde-Garonne-Dordogne watershed. Ontogenetic changes in otolith Sr/Ca were assessed in two groups of control fish that were kept in one of either two constant salinities (fresh water or seawater). X-ray electron microprobe (wavelength dispersive spectrometry, WDS) analyses of Sr/Ca ratios in the otoliths showed that the change of aquarium was recorded as a Sr/Ca increase (downstream migration) or a Sr/Ca decrease (upstream migration). No ontogenetic effect was detected in otoliths of control fish outside glass eel marks in either group of fish. The electron microprobe (WDS) analysis of the Sr/Ca life (transected in several otoliths of eels caught in the Gironde-Garonne-Dordogne watershed) showed that some of them were migrant eels that had experienced one major habitat shift during their continental life.

The purpose of this study was to quantify the nitrogen (N) inputs to 34 estuaries on the Atlantic and Gulf Coasts of the United States. Total nitrogen (TN) inputs ranged from 1 kg N ha Ϫ1 yr Ϫ1 for Upper Laguna Madre, Texas, to 49 kg N ha Ϫ1 yr Ϫ1 for Massachusetts Bay, Massachusetts. TN inputs to 11 of the 34 estuaries were dominated by urban N sources (point sources and septic systems) and nonpoint source N runoff (5% of total); point sources accounted for 36-86% of the TN inputs to these 11 urban-dominated estuaries. TN inputs to 20 of the 34 estuaries were dominated by agricultural N sources; N fertilization was the dominant source (46% of the total), followed by manure (32% of the total) and N fixation by crops (16% of the total). Atmospheric deposition (runoff from watershed plus direct deposition to the surface of the estuary) was the dominant N source for three estuaries (

In order to classify the trophic state of detritus sink systems, instead of the conventional indicators based on inorganic nutrient availability and algal biomass and productivity in the water column, we used new biochemical descriptors based on the amount of sedimentary organic carbon (C) and nitrogen (N) potentially available to hetero-trophs. We investigated spatial and temporal changes in microphytobenthic biomass, organic matter biochemical com-position, and enzymatically hydrolyzable protein and carbohydrate pools along a northsouth transect in the Marsala lagoon (Mediterranean Sea, Italy) at three stations characterized by different hydrodynamic conditions and organic matter content in the sediment. In the Marsala lagoon water currents decreased from north to south and this pattern was reflected by organic matter distribution and composition. Sediment organic matter concentrations were among the highest reported in the literature and, in the central area where large meadows of the seagrass Posidonia oceanica were present, display a strong dominance of highly refractory carbohydrates. The protein to carbohydrate ratio was always , 1, indi-cating the dominance of aged organic detritus. Microphytobenthic biomass displays an increasing pattern southward, and its contribution to the biopolymeric C pools ranged from negligible in the central sector of the lagoon to 50% in its northern part, indicating that sources of sediment organic C also changed along the hydrodynamic gradient. The per-centage contribution of the enzymatically hydrolyzable fraction of proteins and carbohydrates was inversely related to total protein and total carbohydrate concentrations, respectively, suggesting that bioavailability of organic C and N in-creased with decreasing organic matter content in the sediment and with increasing hydrodynamic regime. Microphyto-benthic contribution to biopolymeric C (as a proxy of autotrophic organic C) and the ratio of the enzymatically digestible fraction to biopolymeric C (as an indicator of organic matter liability) were significantly correlated, suggesting that chlorophyll a sediment content might be used as an indicator of food promptly available to consumers. The present study also highlighted that the ratio of labile (i.e., enzymatically digestible) versus biopolymeric organic C in the sediments tends to decrease with increasing organic matter content, due to the increase of the refractory fraction of organic C.

. Geographic and hydrodynamic characteristics of shallow coastal lagoons. In: L.G. Ward and G.M. Ashley (Editors), Physical Processes and Sedimentology of Siliciclastic-Dominated Lagoonal Systems. Mar. Geol.,. Coastal lagoons can be conveniently separated based on geomorphology into leaky, restricted or choked systems. This subdivision orders coastal lagoons hydrodynamically according to water exchange with the coastal ocean. Leaky systems have the shortest turnover time, restricted lagoons have a longer turnover time, and choked lagoons have the longest turnover time. In leaky coastal lagoons, oscillating tidal currents account for most of the flow variance and mask residual currents due to wind-and freshwater-induced density gradients. In restricted lagoons, tides, winds, and freshwater runoff drive components of the circulation. Winds are usually dominant in causing circulation and mixing in choked lagoons, and water exchange with the coastal ocean largely depends on the hydrologic cycle. Coastal lagoons are usually well mixed, but can exhibit significant horizontal gradients due to freshwater runoff and vertical gradients due to solar radiation or surface cooling. In general, river inflow and heat balance induce stratification in coastal lagoons, whereas winds and tides cause mixing. Coastal lagoons usually trap inorganic sediment and organic matter, thus serving as material sinks. On a geologic time scale, they are short-lived landscape features, with an existence intrinsically linked to filtering efficiency and relative sea-level change as a result of glacioeustatic cycles and local tectonic activity.

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.

One of the primary challenges of the Water Framework Directive (WFD) of the European Union is to provide a guide for the recovery of surface waters from pollution. However, few studies deal with reference conditions according to the WFD in coastal waters. Using the urbanised Laajalahti Bay (Helsinki, Finland) as an example, reference conditions and pollution history were defined using the stratigraphy of diatoms, sediment geochemistry, stable isotopes, sedimentary pigments, long-term monitoring results of water quality, and nutrient-loading. Principal components analysis was used to generate a multidimensional index of water quality on the basis of the sediment data. We distinguished 5 phases: (1) a pre-industrial phase (before ca. 1815); (2) a phase of slight human disturbance (ca. 1815 to 1900); (3) an onset of anthropogenic impact (ca. 1900 to 1955); (4) a severe pollution phase (ca. 1955 to 1975); (5) basin recovery and a phase of internal loading (from ca. 1975 onwards). Phase 2 was used to define reference conditions. Phase 1 was not used as it occurred before the formation of the semi-enclosed bay by post-glacial isostatic land-uplift. There was good agreement between the sedimentary record and the water-quality data during Phase 4. Despite an improvement in water quality after the local municipal treatment plant closed in 1986, Laajalahti Bay is still far from reference conditions due to internal loading.

Biotic factors such as interactions among co-occurring taxa are frequently cited as important in determining how nekton use habitat, yet their effects have rarely been tested experimentally. We investigated the general hypothesis that depth distributions of five taxa common in salt marsh intertidal creeks are affected by the presence of other taxa. Two experiments were conducted in a pair of large (15 m 3 ), multi-level (20, 40, and 60cm water depth) flow-through tanks under fairly stable environmental conditions. During the first experiment, when grass shrimp (Palaemonetes spp.), mummichog (Fundulus heteroclitus), white mullet (Mugil curema), spot (Leiostomus xanthurus), and pinfish (Lagodon rhomboides) were each tested alone, the highest proportions of individuals occupied the intermediate and deepest depths. When all taxa were tested together, the distributions of resident creek taxa, mummichog and grass shrimp, shifted to shallower depths, but the distributions of the seasonal transient taxa, white mullet, spot, and pinfish, did not change. A second experiment was conducted to test the effect of predator presence on grass shrimp depth selection. Neither predatory pinfish nor non-predatory white mullet had a strong influence on grass shrimp depth distribution when tested separately, but grass shrimp shifted to shallower depths in the combined presence of both fish. This suggests that a multipletaxa effect such as increased disturbance or higher encounter frequency influenced the depth selection of grass shrimp. Our results demonstrate that biotic factors are important in shaping distributions of grass shrimp and mummichog in shallow water habitat.

We tested the hypothesis that effects of predation by fish on epibiota are independent of the size of fish and the area foraged. We used cages with different sizes of mesh to exclude fish of different sizes. Sizes of mesh were chosen following observations that there were small (, 200 mm TL) and large (. 200 mm TL) predatory fish at the study site. Predation by fish was intense on oysters and directly or indirectly reduced the density of the gastropod, Bembicium auratum. The cover of algae was positively affected by predation, possibly because predation on oysters created more space for algae. Predation by small fish (toadfish) was intense, but the effects of large fish were negligible. Predation was, however, independent of the sizes of experimental panels (i.e. area foraged) over the range examined (5 3 5, 10 3 10, 20 3 20 cm). Our results highlight the importance of doing experiments to test hypotheses derived from known aspects of the biology of the predators and prey being studied.

This paper reviews research that has taken place on physical oceanography and sedimentology on New Zealand's estuaries and the inner shelf since c. 1967. It includes estuarine sedimentation, tidal inlets, beach morphodynamics, nearshore and inner shelf sedimentation, tides and coastal currents, numerical modelling, short-period waves, tsunamis, and storm surges. An extensive reference list covering both published and unpublished material is included. Formal teaching and research programmes dealing with coastal landforms and the processes that shape them were only introduced to New Zealand M91078

Inputs of fresh water and grazing both can control aquatic food webs, but little is known about the relative strengths of and interactions between these controls. We use longterm data on the food web of the freshwater Hudson River estuary to investigate the importance of, and interactions between, inputs of fresh water and grazing by the invasive zebra mussel (Dreissena polymorpha). Both freshwater inputs and zebra mussel grazing have strong, pervasive effects on the Hudson River food web. High flow tended to reduce population size in most parts of the food web. High grazing also reduced populations in the planktonic food web, but increased populations in the littoral food web, probably as a result of increases in water clarity. The influences of flow and zebra mussel grazing were roughly equal (i.e., within a factor of 2) for many variables over the period of our study. Zebra mussel grazing made phytoplankton less sensitive to freshwater inputs, but water clarity and the littoral food web more sensitive to freshwater inputs, showing that interactions between these two controlling factors can be strong and varied.

The quantification and monitoring of sediment dynamics in estuaries has received plenty of attention in recent years due to both economic and environmental interests. Numerical models have been widely applied for predicting the morphodynamic evolution of these areas. However, the degree of uncertainty of these models is often very high due to the lack of measurements necessary for a complete model calibration and validation. In this paper, different methods have been integrated to overcome these limitations. The hydrodynamics and suspended sediment transport in the IJzer estuary were estimated by means of field data and with the use of a two-dimensional hydrodynamic model coupled to a morphodynamic model. Tidal pumping was recognized as the main driving mechanism of sediments inside the estuary. Erosion-deposition areas calculated with the numerical model were compared to the locations and volumes of dredged material. Model results and measurements were generally in good agreement. Additional support for the morphodynamic model results came from airborne hyperspectral images acquired in 2001 and 2005.

Water quality controls involve large number of variables and observations, often subject to some outliers. An outlier is an observation that is numerically distant from the rest of the data or that appears to deviate markedly from other members of the sample in which it occurs. An interesting analysis is to find those observations that produce measurements that are different from the pattern established in the sample. Therefore, identification of atypical observations is an important concern in water quality monitoring and a difficult task because of the multivariate nature of water quality data. Our study provides a new method for detecting outliers in water quality monitoring parameters, using oxygen and turbidity as indicator variables. Until now, methods were based on considering the different parameters as a vector whose components were their concentration values. Our approach lies in considering water quality monitoring through time as curves instead of vectors, that is to say, the data set of the problem is considered as a time-dependent function and not as a set of discrete values in different time instants. The methodology, which is based on the concept of functional depth, was applied to the detection of outliers in water quality monitoring samples in San Esteban estuary. Results were discussed in terms of origin, causes, etc., and compared with those obtained using the conventional method based on vector comparison. Finally, the advantages of the functional method are exposed.

The Southwest Florida Water Management District has implemented a management approach for unimpounded rivers that limits withdrawals to a percentage of streamflow at the time of withdrawal. The natural flow regime of the contributing river is considered to be the baseline for assessing the effects of withdrawals. Development of the percent-of-flow approach has emphasized the interaction of freshwater inflow with the overlap of stationary and dynamic habitat components in tidal river zones of larger estuarine systems. Since the responses of key estuarine characteristics (e.g., isohaline locations, residence times) to freshwater inflow are frequently nonlinear, the approach is designed to prevent impacts to estuarine resources during sensitive low-inflow periods and to allow water supplies to become gradually more available as inflow increases. A high sensitivity to variation at low inflow extends to many invertebrates and fishes that move upstream and downstream in synchrony with inflow. Total numbers of estuarine-resident and estuarine-dependent organisms have been found to decrease during low-inflow periods, including mysids, grass shrimp, and juveniles of the bay anchovy and sand seatrout. The interaction of freshwater inflow with seasonal processes, such as phytoplankton production and the recruitment of fishes to the tidal-river nursery, indicates that withdrawal percentages during the springtime should be most restrictive. Ongoing efforts are oriented toward refining percentage withdrawal limits among seasons and flow ranges to account for shifts in the responsiveness of estuarine processes to reductions in freshwater inflow.

Estuaries represent highly dynamic environments, especially with respect to salinity. Exploitation of these habitats by marine species can assist their ecological success, however they require specialized behavioral strategies as well as physiological abilities to cope with the fluctuations of physical stressors. The Valdivia River estuary, southern Chile, is a site of high larval recruitment and juvenile abundance of the commercial crab species Cancer edwardsii, particularly during the spring and summer months. This estuary experiences severe low salinity events (b7.5) for periods exceeding 6 h, that are associated with rainfall events and the subsequent higher flow rates of the tributaries. To determine the strategies employed by juvenile crabs living in the inner portions of the estuary in the face of changes in salinity conditions, we evaluated their survival and behavioral responses when exposed to a salinity gradient. Early juveniles were incubated at salinities of 0, 7.5, 15-22.5, 32 and crab mortality was recorded after 1, 6 and 12 h of exposure. In addition, early juveniles were experimentally exposed to continuous and gradual changes in saline conditions to evaluate their behavior, which was recorded on video. The main results were (1) despite most Cancer species being considered weak osmoregulators, 30% of individuals of C. edwardsii were able to survive freshwater conditions for 12 h. (2) burying and not quiescence behavior was associated with a drop in salinity, (3) in severe hyposaline conditions, the crabs increased their survival burying in the substrate, probably using higher salinity (N 22) interstitial water. Our findings suggest that burying behavior plays a key role in allowing the crabs inhabit inner estuarine areas where sudden and unexpected severe hyposalinity events occur.

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.

Please direct any queries regarding use or permissions to [email protected] Development and validation of a GC-MS method for the evaluation of 17 endocrine disruptor compounds, including phytoestrogens and sitosterol, in coastal waterstheir spatial and seasonal levels in Porto costal region (Portugal) ABSTRACT A gas chromatography with mass spectrometric detection (GC-MS) method was developed and optimized for the determination of 17 endocrine disrupting compounds (EDCs) in coastal water samples. The evaluated EDCs were from different origins and included estrogens, bisphenol A, alkylphenolethoxylates, alkylphenols, phytoestrogens and sitosterol (SITO). The EDCs were extracted from samples using Oasis HLB (Hydrophilic-Lipophilic Balance) cartridges and derivatized with N,Obis(trimethylsilyl)trifluoroacetamide (BSTFA) added with 1% trimethylchlorosilane (TMCS). The validation parameters revealed that this method was highly specific for all assayed compounds (>99%) and the linearity of the calibration curves showed a correlation higher than 0.99. The detection limits were at low ng/L level and the recovery rates were higher than 70%. The performance of the method was checked using coastal water samples taken every 2 months during 2009-2010 from the Douro River estuary and the Porto coastline (Portugal). These data revealed that approximately 98.0% of the analyzed compounds showed levels above their limits of detection (LODs). The measured estrogens (2-20 ng/L) and industrial pollutants (up to 1.1 μg/L) were in biologic hazardous concentrations. Besides, a clear seasonal pattern of fluctuation was established for phytoestrogens and SITO. The physicochemical data, namely the amounts of nitrates, nitrites and phosphorous, confirmed the low water quality of this area.

The PCB contamination of fish from the Gironde Estuary (France) was investigated. PCB distribution differed between lean, low-fat and high-fat species. A process of biomagnification was observed in the Gironde estuarine fish assemblage. Health concerns about fish flesh contamination were revealed.

We examined variations in the juvenile life history of fall-spawning Chinook salmon, Oncorhynchus tshawytscha, for evidence of change in estuarine residency and migration patterns following the removal of dikes from 145 ha of former salt-marsh habitat in the Salmon River estuary (Oregon). Mark-recapture studies and abundance patterns in the estuary during 2000e2002 describe the following life-history types among Chinook salmon: (1) fry disperse throughout the estuary, and many move into restored tidalmarsh habitats in the early spring soon after emergence; (2) juveniles reside in freshwater for several months, enter the estuary in June or July, and remain for (a) a few weeks or (b) several months before entering the ocean; and (3) juveniles enter the ocean later in the fall after an extended period of rearing upriver and/or in the estuary. The absence of fry migrants in the estuary during spring and early summer in 1975e1977 d a period that precedes restoration of any of the diked marshes d and the extensive use of marsh habitats by fry and fingerlings AprileJuly, 2000e2002 indicate that wetland restoration has increased estuarine rearing opportunities for juvenile Chinook salmon. Year-to-year patterns of estuarine rearing and abundance by juvenile salmon may be influenced by flood and drought conditions that affected adult spawner distribution and over-winter survival of salmon eggs. However, persistent changes in spawner distribution since 1975e1977, including the concentration of hatchery strays in the lower river, may account for the large proportion of fry that now disperse into the estuary soon after emergence in the spring. Although few of these earliest migrants survived to the river mouth, many fry and fingerlings from mid-and upper-basin spawning areas distributed throughout a greater portion of the estuary during the spring and summer and migrated to the ocean over a broader range of sizes and time periods than thirty years ago. The results suggest that wetland recovery has expanded life history variation in the Salmon River population by allowing greater expression of estuarine-resident behaviors.

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

The feasibility of various techniques for the separation and quantification of sediment and sediment porewaters for total Hg and methylmercury (MMHg)scentrifugation, sediment filtration, whole core squeezing, and dialysis membrane techniques (peepers)swere investigated in estuarine sediments. The concentration and distribution of iron, manganese, MMHg, and total Hg in porewaters were compared to ascertain which method provided the best technique for the collection of large volume porewater samples. Direct filtration techniques did not provide sufficient sample volume. Our studies confirmed the need to filter in an inert atmosphere. Processing in an inert atmosphere is also required for centrifugation. Centrifugation was the most difficult method, requiring extensive operator training and much attention to detail during sample processing. Core squeezing is a viable alternative but suffers from sample size problems and potential artifacts due to oxidation during processing. While peepers have advantages, the investigations here show that they need to be completely degassed before they provide reliable Hg speciation measurements, especially as they were constructed from Teflon, which can store significant amounts of oxygen. The need to deoxygenate the peepers compromises their use as a routine separation method for Hg. On the basis of the need for large volumes and the large number of samples to be collected, we concluded that centrifugation was the most reliable method for the determination of Hg and MMHg in estuarine porewaters.

Advances in sensor design and data analysis techniques are making remote sensing systems practical and attractive for use in research and management of coastal ecosystems, such as wetlands, estuaries, and coral reefs. Multispectral and hyperspectral imagers are available for mapping coastal land cover, concentrations of organic/inorganic suspended particles, and dissolved substances in coastal waters. Thermal infrared scanners can map sea surface temperatures accurately and chart coastal currents, while microwave radiometers can measure ocean salinity, soil moisture, and other hydrologic parameters. Radar imagers, scatterometers, and altimeters provide information on ocean waves, ocean winds, sea surface height, and coastal currents, which strongly influence coastal ecosystems. Using airborne light detecting and ranging systems, one can produce bathymetric maps, even in moderately turbid coastal waters. Since coastal ecosystems have high spatial complexity and temporal variability, they frequently have to be observed from both satellite and aircraft in order to obtain the required spatial, spectral, and temporal resolutions. A reliable field data collection approach using ships, buoys, and field instruments with a valid sampling scheme is required to calibrate and validate the remotely sensed information. The objective of this paper is to present an overview of practical remote sensing techniques that can be used in studies of coastal ecosystems.

Housatonic River estuary in southwestern Connecticut. Nekton were sampled on nine spring high tide events from May to October 2000 using bottomless lift nets positioned between 0-5 and 10-20 m fi°oin the creek edge. Flooding depth, duration, and frequency were measured froin each vegetation type during each sampling iilontfi. Benthic macroinverte= brate density was also measured within each vegetation type in May, July, and Septembei: Frequency of flooding was 52% lower and flooding depth and duration were also significantly reduced in P. austrMis relative to S. agterniflora. A total of 4,197 individuals representing 7 species, mostly Pahwmonetes pugio (dagger-blade grass shrimp) and Fund*dus heteroclitus(common mummichog), were captured. P. pugio densities were significantly greater in S. alterniflora as were benthic macroinvertebrate density and taxa richness during May, but not during June or Octoben Total fish density was not significantly different between P. auslrafis and S. Mt~mnifloru and was independent of location mi the marsh. Significantly more juvenile F. hete~oclitus were collected within S. alt~niflora relative to P. australis in June and July; suggesting that recruitment of this species may be lower in P. australis habitat. Fish density generally did not vary predictably across the range of flooding depth and duration; there was a positive relationship between flooding depth and fish density in S.

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.

Population parameters are necessary in order to understand the health of any fishery to determine appropriate management measures. The prawn Macrobrachium equidens is an important component of the artisanal Macrobrachium fishery of the Cross River Estuary, contributing about 3.8 and 2.9% by number and weight, respectively, to the total catch of the multi-species Macrobrachium fishery of the area. Growth and mortality parameters of this prawn Macrobrachium equidens was studied from length-frequency data using ELEFAN Programme of FAO-ICLARM Stock Assessment Tools (FiSAT), and the following results were obtained: asymptotic length (L ∞ ) = 107.12 mm, growth constant K = 1.25/year, oscillation constant C = 1, Winter Point WP = 0.35, total mortality (Z) = 4.97/year, natural mortality (M) = 2.69/year, fishing mortality (F) = 2.28/year and exploitation rate (E) = 0.46. The fishery is on the verge of over-exploitation. Regulatory management measure to improve the contributions of this fishery to the overall prawn landing in the area is imperative. The most realizable management option is the closed period, during the reproductive season. This implies periodic closures at two alternate moon phases during the peak of reproductive activities. This option eliminates the contentious closure of the fishery during the most 'lucrative fishing season'. The fisherfolk will easily adopt these short closure periods and cooperate to ensure sustainable management.

We examined variations in organic carbon (OC) pools and microplanktonic carbon fluxes at three stations in the Hudson River estuary during 12 cruises between Octobers of 1996 and 1998. Phytoplankton biomass and net primary production varied from 5 to 40 mol C L Ϫ1 and 0.3 to 318.3 mmol C m Ϫ2 d Ϫ1 , respectively. Biomass and production of bacterioplankton in the surface layer commonly exceeded those of phytoplankton, varying from 0.2 to 72 mol C L Ϫ1 and 1.4 to 70 mmol C m Ϫ2 d Ϫ1 , respectively. Median planktonic respiration varied from 275 to 605 mmol CO 2 m Ϫ2 d Ϫ1 between stations along the salinity gradient. Primary production/respiration (P : R) ratios varied temporally and spatially between 0.003 and 6.60, averaging 0.22. Carbon mass balances revealed that under low river discharges (Ͻ250 m 3 s Ϫ1), the estuary processed 2.4-fold more carbon internally and advected 2.7-fold less carbon seaward than under higher flows. Annual OC budgets suggest that ϳ19 ϫ 10 9 mol C yr Ϫ1 of total organic carbon (TOC) entered the estuary, whereas 30 ϫ 10 9 mol TOC yr Ϫ1 was exported seaward, representing a net gain of 11 ϫ 10 9 mol TOC yr Ϫ1 within the estuary. Microplankton processed ϳ32 ϫ 10 9 mol C yr Ϫ1 , of which 5.6 ϫ 10 9 mol C was attributed to photo-and chemoautotrophic (ϳ72%) and heterotrophic (ϳ28%) production; the remainder was respired to CO 2 (26.5 ϫ 10 9 mol CO 2 yr Ϫ1). The persistent imbalance between carbon oxidation and carbon fixation strongly suggests that the Hudson River estuary usually is net heterotrophic and is a significant source of inorganic carbon to the coastal ocean and atmosphere.

The distribution, sources and fate of mercury (Hg) in the water column of the Gulf of Trieste (northern Adriatic Sea), affected by the Hg polluted river SocayIsonzo for centuries draining the cinnabar-rich deposits of the Idrija mining district (NW Slovenia), were studied in terms of total and dissolved Hg, reactive Hg, total and dissolved methylmercury (MeHg), mesozooplankton Hg and MeHg, and sedimentation rates of particulate Hg. Higher total Hg concentrations in the surface layer were restricted to the area of the Gulf in front of the river plume expanding in a westerly direction. Higher concentrations in bottom water layers were the consequence of sediment resuspension. Dissolved Hg exhibited higher concentrations in the surface layer in the area in front of the river plume. Higher bottom concentrations of dissolved Hg observed at some stations were probably due to remobilization from sediments, including resuspension and benthic recycling. The relationship between dissolved Hg in the surface layer and salinity showed nonconservative mixing in June 1995 during higher riverine inflow and nearly conservative mixing in September 1995 during lower riverine inflow. Both mixing curves confirm the river SocayIsonzo to be the most important source of total and dissolved Hg, which are significantly correlated, in the Gulf. Reactive Hg is significantly correlated with dissolved Hg, indicating that the majority of dissolved Hg is reactive and potentially involved in biogeochemical transformations. The higher total MeHg in the bottom layer is the result of remobilization of MeHg from sediments including benthic fluxes. Strong seasonal variation of sedimentation rates of particulate Hg was found during a 2-year study in the central part of the Gulf. These variations followed those of total sedimented matter, indicating that sedimented Hg is mostly associated with inorganic matter. About a 2.5-fold higher fluxes of particulate Hg were observed at the depth of 20 m relative to 10 m which is attributed to bottom sediment resuspension. Temporal variability of mesozooplankton Hg and MeHg is the consequence of biomass and species variations, and grazing behaviour. From the preliminary Hg mass balance it appears that the Gulf is an efficient trap for total Hg and a net source of MeHg.

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.

The gelatinous macroplankters Mnemiopsis leidyi and Phyllorhiza punctata are recorded for the first time from the Italian coasts of the Western Mediterranean. In the framework of the CIESM Jellywatch campaign in the summer of 2009, M. leidyi was recorded from the Ligurian, Tyrrhenian, and Ionian Seas, including swarming episodes that, together with those reported from Spain in the same period, suggest a great success of the species in the Western Mediterranean. A single specimen of P. punctata has been recorded from Sardinia. These species do not sting or harm humans and no impact on tourism is expected, but they might harm fisheries by predating on fish eggs and larvae and their prey, zooplankton. The large distribution area of M. leidyi suggests that the species invaded the Western Mediterranean during the summer of 2009, but its establishment is still uncertain, since the populations might not withstand winter conditions. The isolated record of P. punctata just indicates that it can reach this part of the Mediterranean.

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.

Dissolution of diatom biogenic silica (bSiO 2 ) in estuaries and its control by water salinity and bacteria were investigated using the river euryhaline species Cyclotella meneghiniana as a model. Laboratory-controlled bioassays conducted at different salinities with an estuarine bacteria inoculum showed a faster dissolution of diatom bSiO 2 at the lowest salinity where bacteria were the most abundant. However in another experiment, salinity increase clearly enhanced the dissolution of cleaned frustules (organic matter free). The presence of active bacteria might therefore predominate on the effect of salinity for freshly lysed diatoms whereas salinity might rather control dissolution of organic-matterfree frustule remains. Incubation of cultivated diatoms at different protease concentrations revealed that high proteolytic activities had little effect on bSiO 2 dissolution at a 1-month scale in spite of an efficient removal of organic matter from the frustules. Altogether it is hypothesized that bacterial colonization increases bSiO 2 dissolution by creating a microenvironment at the diatom surface with high ectoproteolytic activity but also via the release of metabolic byproducts since the presence of organic matter seems generally to facilitate diatom bSiO 2 dissolution.

The present water quality of the Humber rivers and coastal zone depends on a complex interplay of factors, including physical ones, such as the underlying geology, which influences soil type, climatic ones, such as the rainfall, which influences runoff, socio-economic ones, which influence present-day human activities in the catchment, and the legacy of former activities, such as contaminated sediments from mining. All of these factors affect the fluxes of nutrients and other contaminants to the rivers and coastal zone. The Water Framework Directive (WFD) requires the production of a river basin management plan intended to lead to the achievement of good chemical and ecological status for all water bodies in the catchment over the next two decades. This paper provides an overview of the current environmental and socio-economic state of the Humber catchment and coastal zone, and broadly examines how socio-economic drivers affect the fluxes of nutrients and contaminants to the coastal zone, using the driverpressure-state-impact-response (DPSIR) approach. This is followed by an overview of future research, describing the use of scenarios to simulate future fluxes and provide a consistent framework to evaluate potential policies to improve water quality in the estuary. The Humber catchment is one of eight case studies within a European research project, EUROCAT (EVK1- CT-2000-00044), which aims to achieve integrated catchment and coastal zone management by analysing the response of the coastal sea to changes in fluxes of nutrients and contaminants from the catchments. For the Humber case study, the research focuses on the fluxes of two nutrient elements, N and P, and four metal contaminants, As, Cu, Pb and Zn. The project requires the integration of scientific and socio-economic approaches, bringing together quantitative environmental data garnered for individual river catchments and coastal zones in previous research programmes, and local and regional socio-economic data, to aid decision-makers in their search for integrated and sustainable coastal zone management strategies. ᮊ

Even though the Queque´n Grande River Estuary has economic and strategic importance from an oceanographic point of view, it has been ignored until recently. Nevertheless, many anthropogenic modifications (i.e., dredging, jetty and harbour construction, etc.) have taken place in the last 100 years which, most of them, have resulted in significative economic expenses to the harbour and city authorities due to the lack of adequate prior studies. The purpose of this article is to provide a review of the present status of the geomorphology and main physical characteristics of the estuary and describe the effects of these man-made modifications upon the estuary. Data were gathered in several field cruises from 1994 to 2000 plus from continuous recording devices installed at or near the estuary directed to define the present geomorphologic and oceanographic conditions of the estuary and to establish a monitoring program. The ultimate goal is to provide some practical solutions in diminishing the maintenance of the harbour and to provide pollution-control devices.

The potential impact of human disturbance on wintering waterbirds using intertidal mudflats was considered by relating their numbers to the presence of nearby footpaths, roads, railroads, and towns. Data were obtained for six English estuaries from the Wetland Bird Survey Low Tide Count scheme. Counts were undertaken monthly from November to February, and data were available for an average of 2.8 years per estuary for the period 1992-1993 to 1999 -2000. Count sections and the positions of man-made landscape features were mapped using a GIS. Generalized linear models tested whether bird numbers varied according to the estuary, month, area, whether or not the section bordered water, and the pro-portion of each section within a specified distance of each landscape feature. In addition, the proximity of sections to the nearest footpath access point was considered. Numbers of six of nine species, northern shelduck (Tadorna tadorna), red knot (Calidris canutus), dunlin (Calidris alpina), black-tailed godwit (Limosa limosa), Eurasian curlew (Numenius arquata) and common redshank (Tringa totanus), were significantly lower where a footpath was close to a count section, while those of brant (Branta bernicla) were greater. Northern shelduck, black-bellied plover (Pluvialis squatarola), dunlin, and black-tailed godwit numbers were reduced close to railroads and those of common ringed plover (Charadrius hiaticula), black-bellied plover, and Eurasian curlew close to roads. Common ringed plover numbers were greater close to towns. The relative distances to which species were affected by footpaths corresponded to published information concerning their flight distances in response to human disturbance. The study provided evidence that sustained disturbance associated with footpaths, roads, and railroads reduced local habitat quality for waterbirds and the carrying capacity of estuaries.

Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high quality ecological information regarding the potential impacts, in order to develop sound management strategies. Crab-tiling is a largely unregulated and un-researched fishery, which operates commercially in the south-west UK. The target species is the green crab Carcinus maenas. Those crabs which are pre-ecdysis and have a carapace width greater than 40 mm are collected to be sold to recreational anglers as bait. Collection involves laying artificial structures on intertidal sandflats and mudflats in estuaries. Crabs use these structures as refugia and are collected during low tide. However, the effect that this fishery has on populations of C. maenas is not known. The impact of crab-tiling on C. maenas population structure was determined by sampling crabs from tiled estuaries and non-tiled estuaries using baited drop-nets. A spatially and temporarily replicated, balanced design was used to compare crab abundance, sizes and sex ratios between estuaries. Typically, fisheries are associated with a reduction in the abundance of the target species. Crab-tiling, however, significantly increased C. maenas abundance. This was thought to be a result of the extra habitat in tiled estuaries, which probably provides protection from natural predators, such as birds and fish. Although crabs were more abundant in tiled estuaries than non-tiled estuaries, the overall percentage of reproductively active crabs in non-tiled estuaries was greater than in tiled estuaries. As with most exploited fisheries stocks, crabs in exploited (tiled) estuaries tended to be smaller, with a modal carapace width of 20-29 mm rather than 30-39 mm in non-tiled estuaries. The sex ratio of crabs however; was not significantly different between tiled and non-tiled estuaries. These results illustrate the potential to manage fished populations using habitat provision to mitigate the effects of fishing pressure.