East Coast Estuaries Research Articles

Investigation and comparative analysis of ecological risk for heavy metals in sediment and surface water in east coast estuaries of India

The sediments and surface water from 8 stations each from Dhamara and Paradeep estuarine areas were sampled for investigation of heavy metals, Cd, Cu, Pb, Mn, Ni, Zn, Fe, and Cr contamination. The objective of the sediment and surface water characterization is to find the existing spatial and temporal intercorrelation. The sediment accumulation index (Ised), enrichment index (IEn), ecological risk index (IEcR) and probability heavy metals (p-HMI) reveal the contamination status with Mn, Ni, Zn, Cr, and Cu showing permissible (0 ≤ Ised ≤ 1, IEn ˂ 2, IEcR ≤ 150) to moderate (1 ≤ Ised ≤ 2, 40 ≤ Rf ≤ 80) contamination. The p-HMI reflects the range from excellent (p-HMI = 14.89-14.54) to fair (p-HMI = 22.31-26.56) in off shore stations of the estuary. The spatial patterns of the heavy metals load index (IHMc) along the coast lines indicate that the pollution hotspots are progressively divulged to trace metals pollution over time. Heavy metal source analysis coupled with correlation analysis and principal component analysis (PCA) was used as a data reduction technique, which reveals that the heavy metal pollution in marine coastline might originate from redox reactions (FeMn coupling) and anthropogenic sources.

Unusually high sedimentary metal concentrations in intermittently closed and open lakes and lagoons (ICOLLs) in the northern lagoons of Sydney (Australia)

The environmental status of three Intermittently Closed and Open Lakes and Lagoons (ICOLLs) (Manly, Curl Curl and Dee Why Lagoons) in northern Sydney (Australia) were assessed using sedimentary metals. Results identified the highest sedimentary metal enrichment in the Australian central east coast estuaries, with only a moderate ecological risk. A comparison with surficial sediment concentrations from 1996 to 2008 indicated declining metal concentrations, which is largely supported by subsurface metals data. Extensive low-lying areas of the catchments were historically reclaimed by infilling wetlands, which may have resulted in contaminated groundwater influx to the lagoons. An analysis of the sedimentary metals mix in lagoons surrounded by extensive infilling and estuaries with minor reclamation were statistically distinct. ICOLLs are environmentally sensitive due to large catchment/estuary ratios and restricted access to the ocean. A full set of baseline data is provided to support future monitoring of anthropogenic impacts on the system.

Spatial patterns of abundance and shell morphology of two gastropod species associated with different morphologies of an intertidal seaweed

Patterns of abundance and shell morphology of intertidal gastropods are typically thought to depend on environmental conditions, but ecosystem engineers such as canopy-forming seaweeds can also influence these traits. The intertidal seaweed Hormosira banksii (H. banksii) is an abundant species and important ecosystem engineer on rocky shores and estuaries in south-east Australia, where it creates thick canopies colonized by a range of invertebrates, particularly gastropods. In Tasmania (southern Australia), H. banksii shows large variability in thallus length and structure, with different algal morphologies on coasts and in estuaries. In this study, individuals of two gastropod species were sampled from different habitats (north coast, east coast and northern estuaries) to: (1) describe the spatial variability in their abundance and shell morphology, and (2) understand if any relationship exists between H. banksii morphology and gastropod shell morphology. Gastropod abundance and morphology were variable, but multivariate analysis suggested a marginal influence of H. banksii morphological traits, particularly vesicle size, on the patterns observed. As the two gastropod species use habitat differently and that different H. banksii morphs occur in different locations, our results suggest that both algal morphology and environmental conditions may affect gastropod abundance and shell morphology across the different habitats. Hence, from these results a model can be developed and tested in subsequent experimental work to tease apart the effects of seaweed morphology from environmental conditions.

Pharmaceuticals, personal care products, food additive and pesticides in surface waters from three Australian east coast estuaries (Sydney, Yarra and Brisbane)

The detection rates of pharmaceuticals (Ps), personal care products (PCPs), current-use pesticides (CUPs) and a food additive (FA) in Brisbane River estuary (Queensland), Sydney estuary (New South Wales) and the Yarra River estuary (Melbourne, Victoria) were: Ps: 16/25, 7/25 and 12/25, respectively, CUPs; 28/53, 5/53 and 23/53, respectively, PCPs: 1/3, 0/3 and, 1/3, respectively and FA; 1/1, 1/1 and 1/1, respectively. Diuron was measured in all estuarine samples, simazine, MCPA and 2,4 D were also commonly measured. Pharmaceuticals: carbamazepine, iopromide paracetamol tramadol and venlafaxine were also commonly measured across the estuaries. Generally, analytes were prominent in Brisbane River estuary, followed by Yarra River/Sydney estuary. Inputs of Ps are likely from leakages or effluents of WWTPs; CUPs are potentially from agricultural and parklands via surface run-off in Brisbane River estuary, while for Sydney and Yarra estuaries, which have separate stormwater and sewer systems, sources are likely to be ingression and leakage.

Predicting visual clarity and light penetration from water quality measures in New Zealand estuaries

Estuaries are biogeochemically and physically dynamic environments, resulting in diverse optical water properties that vary in space and time. This natural variability challenges effective monitoring. We develop semi-empirical linear models of the two main water clarity aspects, visual clarity and light penetration, as functions of more routinely monitored and/or modelled water quality measures, to simplify approximations and allow more expansive modelling in space and time. At multiple points along salinity gradients in six northern New Zealand estuaries, we made discrete measurements of horizontal black disk visibility (yBD) and downwelling irradiance attenuation (Kd(PAR)), with surface concentrations of the main light-attenuating constituents (LACs): total suspended solids (TSS), coloured dissolved organic matter (CDOM – ag(340)), and phytoplankton chlorophyll a (Chl.a). Estuaries on the east coast (Tauranga and Tairua Harbours) were relatively clear compared to those on the west coast (Kaipara and Raglan Harbours). Although Kd(PAR) (controlling light penetration and euphotic zone depth) and yBD (inversely proportional to beam attenuation at 550 nm, controlling visual clarity) were strongly corelated over all estuaries (r2 > 0.8), there were small, yet significant, differences between regression lines in different estuaries. This suggests regional differences in light scattering and absorption properties of the LACs. Variability in water clarity was mainly accounted for by TSS alone in west coast Kaipara Harbour sub-estuaries (r2 > 0.7), while in east coast estuaries, TSS was a weak predictor (r2 < 0.5), and prediction was significantly improved by accounting for CDOM (r2 > 0.7). West coast Raglan Harbour had intermediary responses. In most cases, the inclusion of CDOM significantly improved estuary models, but Chl.a was a significant term only in a few cases, such as during one survey on the Kaipara River sub-estuary. Co-linearity of LACs was an issue in some cases for semi-empirical models. The application of a literature-derived Lambert-Beer Law (LBL) type model to our data more effectively partition the contributions of the LACs, which confirmed and quantified differences between west coast (TSS dominant), and east coast (TSS + CDOM) estuaries. Although we expect that ‘simple’ semi-empirical models will have wide practical application for estimating visual clarity and light penetration in estuaries in New Zealand and elsewhere, consideration of all LACs in an LBL type model is advised across entire estuaries, and local verification and ‘tuning’ is desirable.

Air–water CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; evasion from US East Coast estuaries

Abstract. This study presents the first regional-scale assessment of estuarine CO2 evasion along the US East Coast (25–45° N). The focus is on 42 tidal estuaries, which together drain a catchment of 697 000 km2 or 76 % of the total area within this latitudinal band. The approach is based on the Carbon–Generic Estuary Model (C-GEM) that allows the simulation of hydrodynamics, transport, and biogeochemistry for a wide range of estuarine systems using readily available geometric parameters and global databases of seasonal climatic, hydraulic, and riverine biogeochemical information. Our simulations, performed using conditions representative of the year 2000, suggest that, together, US East Coast estuaries emit 1.9 Tg C yr−1 in the form of CO2, which corresponds to about 40 % of the carbon inputs from rivers, marshes, and mangroves. Carbon removal within estuaries results from a combination of physical (outgassing of supersaturated riverine waters) and biogeochemical processes (net heterotrophy and nitrification). The CO2 evasion and its underlying drivers show important variations across individual systems, but reveal a clear latitudinal pattern characterized by a decrease in the relative importance of physical over biogeochemical processes along a north–south gradient. Finally, the results reveal that the ratio of estuarine surface area to the river discharge, S∕Q (which has a scale of per meter discharged water per year), could be used as a predictor of the estuarine carbon processing in future regional- and global-scale assessments.

Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state.

A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes that the bulk volume of sediment equates to the sum of self‐packing volumes of organic and mineral components or BD = 1/[LOI/k1 + (1‐LOI)/k2], where k1 and k2 are the self‐packing densities of the pure organic and inorganic components, respectively. The model explained 78% of the variability in total BD when fitted to 5075 measurements drawn from 33 wetlands distributed around the conterminous United States. The values of k1 and k2 were estimated to be 0.085 ± 0.0007 g cm−3 and 1.99 ± 0.028 g cm−3, respectively. Based on the fitted organic density (k1) and constrained by primary production, the model suggests that the maximum steady state accretion arising from the sequestration of refractory organic matter is ≤ 0.3 cm yr−1. Thus, tidal peatlands are unlikely to indefinitely survive a higher rate of sea‐level rise in the absence of a significant source of mineral sediment. Application of k2 to a mineral sediment load typical of East and eastern Gulf Coast estuaries gives a vertical accretion rate from inorganic sediment of 0.2 cm yr−1. Total steady state accretion is the sum of the parts and therefore should not be greater than 0.5 cm yr−1 under the assumptions of the model. Accretion rates could deviate from this value depending on variation in plant productivity, root:shoot ratio, suspended sediment concentration, sediment‐capture efficiency, and episodic events.

Source determination of benzotriazoles in sediment cores from two urban estuaries on the Atlantic Coast of the United States

Benzotriazoles (BZTs) are used in a broad range of commercial and industrial products, particularly as metal corrosion inhibitors and as ultraviolet (UV) light stabilizer additives in plastics and polymers. In this study, dated sediment cores from two east coast estuaries were analyzed for commonly used BZTs. In Narragansett Bay, UV stabilizing BZTs (UV-BZTs) were present at high levels from 1961 on, reflecting their patent date, local production and long-term preservation in sediment. In Salem Sound, UV-BZTs were present at concentrations consistent with other coastal marine locations not influenced by BZT production. Anticorrosive BZTs (AC-BZTs) were found in both cores, with the highest levels reported to date present in Narragansett Bay, indicating sorption to, and preservation in, sediments. This study revealed that both classes of BZTs have remained structurally intact over time in coastal sediment cores, demonstrating their resistance to degradation and persistence in environmental compartments.

The relevance of mitochondrial lineages of Taiwanese cultured grey mullet,Mugil cephalus, to commercial products of Roe

Mugil cephalus is an important aquaculture species in Taiwan with highly valuable roe. In order to obtain its roe, mullet fry from various Taiwan estuaries are raised in aquaculture ponds until maturity. However, not all female mullets have developed ovaries. Therefore, we have attempted to use DNA profiling to aid selection of mullet fry for aquaculture. A large proportion of North coast mullet and some West coast mullet were identified as cytochrome oxidase subunit I (COI) mitochondrial lineage 1. COI mitochondrial lineage 2 was dominant in the west and east coast estuaries, whereas COI mitochondrial lineage 3 was fewest and only was present in Chang-hua county (middle west of Taiwan). The gonadosomatic index (GSI) of lineage 1 individuals ranged from 0 to 5, no matter where the mullet fry were captured. The GSI of both the west and east coast lineage 2 individuals ranged from 0 to over 15, but the GSI of lineage 2 of the I-lan (north east of Taiwan) population was generally lower than that of western populations. These findings suggest that a genetic difference whereby west coast lineage 2 mullet yield heavier roe although the body size of lineage 1 individual is larger than that of lineage 2. Thus, lineage 2 individuals with their normal GSI distribution are the most economically viable. The application of the rapid screening of mitochondrial lineages is expected to help aquaculture farmers cultivate lineage 2 fry for roe production rather than lineage 1.

Net ecosystem production and organic carbon balance of U.S. East Coast estuaries: A synthesis approach

AbstractNet ecosystem production (NEP) and the overall organic carbon budget for the estuaries along the East Coast of the United States are estimated. We focus on the open estuarine waters, excluding the fringing wetlands. We developed empirical models relating NEP to loading ratios of dissolved inorganic nitrogen to total organic carbon, and carbon burial in the sediment to estuarine water residence time and total nitrogen input across the landward boundary. Output from a data‐constrained water quality model was used to estimate inputs of total nitrogen and organic carbon to the estuaries across the landward boundary, including fluvial and tidal‐wetland sources. Organic carbon export from the estuaries to the continental shelf was computed by difference, assuming steady state. Uncertainties in the budget were estimated by allowing uncertainties in the supporting model relations. Collectively, U.S. East Coast estuaries are net heterotrophic, with the area‐integrated NEP of −1.5 (−2.8, −1.0) Tg C yr−1 (best estimate and 95% confidence interval) and area‐normalized NEP of −3.2 (−6.1, −2.3) mol C m−2 yr−1. East Coast estuaries serve as a source of organic carbon to the shelf, exporting 3.4 (2.0, 4.3) Tg C yr−1 or 7.6 (4.4, 9.5) mol C m−2 yr−1. Organic carbon inputs from fluvial and tidal‐wetland sources for the region are estimated at 5.4 (4.6, 6.5) Tg C yr−1 or 12 (10, 14) mol C m−2 yr−1 and carbon burial in the open estuarine waters at 0.50 (0.33, 0.78) Tg C yr−1 or 1.1 (0.73, 1.7) mol C m−2 yr−1. Our results highlight the importance of estuarine systems in the overall coastal budget of organic carbon, suggesting that in the aggregate, U.S. East Coast estuaries assimilate (via respiration and burial) ~40% of organic carbon inputs from fluvial and tidal‐wetland sources and allow ~60% to be exported to the shelf.

Transport and retention of the mitten crab (&lt;I&gt;Eriocheir sinensis&lt;/I&gt;) in a Mid-Atlantic estuary: Predictions from a larval transport model

Invasive species cause extensive ecological damage in freshwater and marine habitats and are a threat to biodiversity in aquatic ecosystems world-wide. One such species, the Chinese mitten crab, Eriocheir sinensis, has invasive populations in northern Europe and San Francisco Bay, and there are confirmed reports of breeding female crabs in both the Chesapeake and Delaware Bays. Despite their threat to these ecosystems, there are still large gaps in the current understanding of this species’ larval biology that are critical to predicting the potential for large populations to establish in East Coast bays and estuaries. We addressed these issues by using a physical circulation model of Delaware Bay and the adjacent coastal ocean coupled to a modified particle advection scheme. We used this model to examine the effects of different physical mechanisms and larval behavior on transport, retention, and settlement of larvae in the bay. The circulation model produced flow fields using observed winds and river discharge for 2006 as well as systematic variations of river discharge and wind direction. Since little is known regarding mitten crab larval behavior, the larval component was purposefully general and incorporated a suite of behaviors such as tidal, diel, and ontogenetic vertical migration; however, results of this study showed that vertical migration affects the magnitude, but not locations of larval settlement. Simulations revealed that changes in the time and location of spawning can result in large variations in retention and settlement of larvae in Delaware Bay and the coastal ocean, due to seasonal variations of the physical flow field. Overall results of our study showed that the estuarine and coastal circulation typically found along the Middle Atlantic coast of the United States can result in significant retention of new and established E. sinensis populations in large estuaries as well as transport of larvae to new coastal locations.

Allelopathic effects of Cochlodinium polykrikoides isolates and blooms from the estuaries of Long Island, New York, on co-occurring phytoplankton

The toxic dinoflagellate Cochlodinium polykrikoides forms harmful algal blooms in coastal ecosystems around the world, to the great detriment of fisheries. Here we describe the allelo- pathic effects of C. polykrikoides blooms and strains isolated from east coast estuaries of the United States on natural communities and cultured phytoplankton. The allelopathic effects of C. poly- krikoides cultures and blooms on the target microalgal cells included loss of motility, distortion of cell morphology, and 60 to 100% cell mortality within minutes to 24 h. Allelopathy by C. polykrikoides on target microalgae was dependent on the relative and absolute cell abundance of each species as well as exposure time. The ability of C. polykrikoides cultures to kill target algae connected through a 5 µm mesh nylon membrane indicated that the allelopathic agents were extracellular and that direct cellular contact with target cells was not required for C. polykrikoides to exhibit allelopathy. Freez- ing, heating, sonication, and filtration of C. polykrikoides cells led to the complete loss of their allelo- pathic effect, suggesting that the allelopathic agents were short-lived and dependent on cell viabil- ity. Additions of the reactive oxygen species (ROS)-scavenging enzymes peroxidase and catalase into C. polykrikoides cultures eliminated or lessened their allelopathic effects, suggesting ROS-like chemical(s) were responsible for the allelopathy. These results are consistent with bioassays of fish and shellfish larvae with C. polykrikoides, suggesting that its toxicity to fish and shellfish larvae and its allelopathic effects on algae are caused by the same agents. The rapid and strong allelopathic effects exhibited by C. polykrikoides suggest allelopathy may facilitate blooms by eliminating com- peting species.

Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary.

The Disappearance of Oyster Reefs from Eastern Australian Estuaries—Impact of Colonial Settlement or Mudworm Invasion?

Oysters have been harvested on the east coast of Australia for many thousands of years. Coastal Aboriginal communities used the extensive estuarine oyster resource and may have farmed oysters by establishing shell cultch beds in shallow areas of estuaries. The British colonization of Australia commenced in 1788 and oysters were initially used for food and production of lime. Concerns about unsustainable exploitation led to introduction of legislation that directed the oyster industry to aquaculture in 1884. Translocation of oyster stock for fattening, from New Zealand to Australian east coast estuaries, was encouraged. Here evidence is presented that this activity resulted in “mudworm disease” appearing in oyster farming estuaries on the Australian east coast between 1880 and 1900. The pandemic permanently destroyed natural sub-tidal oyster reefs and forced the oyster industry to adopt avoidance farming techniques including intertidal farming to cope with mudworm.

Anguilla rostrata glass eel ingress into two, U.S. east coast estuaries: patterns, processes and implications for adult abundance

A time series of American eel Anguilla rostrata glass eel abundance, timing and size from Little Egg Inlet, New Jersey (16 years) and Beaufort Inlet, North Carolina (18 years) was used to provide a better understanding of ingress patterns at two, U.S. east coast estuaries. There was no evidence of synchronous declines in abundance between the two locations; however, at the Little Egg Inlet site, glass eels arrived later in the season and at significantly smaller sizes over the duration of the series. One significant linkage between sites was revealed: abundance was positively correlated with winter precipitation. Precipitation differed between sites annually and was correlated with El Niño at Beaufort Inlet and, to a lesser extent, the North Atlantic Oscillation at Little Egg Inlet. It is hypothesized that glass eels may use freshwater signals to enhance recruitment to local estuaries, thus influencing year‐class strength, yet the relationship between year‐class strength and adult abundance remains unresolved.

Evaluation of management strategies for reducing nitrogen loadings to four US estuaries

In this study we used the Watershed Assessment Tool for Evaluating Reduction Strategies for Nitrogen (WATERSN) model to evaluate a variety of management strategies for reducing nitrogen (N) loads to four US east coast estuaries: Casco Bay, Long Island Sound, Chesapeake Bay and Pamlico Sound. These management strategies encompass reductions in atmospheric emissions and deposition of N from sources including, fossil fuel burning utility emissions and mobile NO x emissions, N treatment in wastewater and controls on agricultural N inputs. We find that in primarily urban watersheds biological removal of N in wastewater treatment produces the greatest reduction in N loading (32–57% reductions), while in less urban watersheds, reductions in agricultural loading are more effective (5–56% reductions) in decreasing N loads to coastal ecosystems. Because anthropogenic N inputs are derived from a variety of sources, we also examined an integrated scenario targeting all major N sources; this resulted in 35–58% reductions in N loading. Nitrogen pollution originates from multiple sources and is transported through several media (air, soil, water); a major challenge of the development of N management strategies will be the control of multiple sources to effectively reduce N loads to estuaries.

Feeding habits of age-0 striped bass,Morone saxatilis, in the mid-Hudson River estuary: Temporal, spatial, and ontogenetic variation

We quantified temporal and spatial variability in diets of 950 juvenile (age-0) striped bass in the Hudson River estuary. We used canonical correspondence analysis to assess the roles of temporal and spatial habitat variability in juvenile diet variation. We found that juvenile striped bass diets in the Hudson River were only modestly comparable to diets in other east coast estuaries. Among-year differences (51.4%) and spatial differences (41.9%) were substantially associated with juvenile striped bass diet. We found ontogeny (2.8%) and within-season variation (9.5%) to only weakly associate with diet variation. Our results indicate that an understanding of the temporal and spatial variation within the Hudson River estuary is vital in understanding variation in feeding by resident juvenile fish.

Assessing perceptions about ecosystem health and restoration options in three east coast estuaries.

Increasingly public and governmental agencies are concerned about revitalizing coastal environments. Understanding how the public uses these areas, and what they see as the most important improvements to these regions is critical to their assessment and management. Uses of three estuaries, and perceptions of possible management and restoration options, were examined for people who were interviewed in the New York/New Jersey Harbor, Manasquan Inlet, and Barnegat Bay, New Jersey. Nearly 90% of the people interviewed listed pollution as New Jersey's most important environmental problem. Most people (68%) used the habitat for outdoor sports, but rated communing with nature, walking, and the provision of open 'green' space as the most valued uses. Pollution prevention was the most often mentioned habitat improvement desired, and people rated removing pollution, cleaning up garbage, and creating more fish breeding habitat the highest. There were significant locational differences in how people used the estuaries, and in how they thought they should be improved. People from Barnegat Bay ranked most uses higher than did people from elsewhere, while the people from Manasquan Inlet rated the importance of most remediation and restoration actions higher. Many of the improvements fall within environmental management, including (rank order from high to low) creating more fish breeding habitat, improving native vegetation, improving habitat for birds, increasing plant diversity, improving habitat for butterflies, and enlarging adjacent marshes. The data provide clear support for the importance of these coastal habitats for communing with nature and having open 'green space' spaces, and for providing recreational opportunities. To enhance their value, people want to remove pollution and improve both the habitat quality and the educational and recreational facilities.

Is Sugary Toxin the Smoking Gun?

PFIESTERIA DEBATE A team of researchers claims to have found more support for the controversial assertion that a toxic microbe called Pfiesteria is responsible for massive fish die-offs along the eastern United States. But the new studies, which include the first rough sketch of the toxin, have failed to convince skeptics. For 10 years, aquatic ecologist JoAnn Burkholder of North Carolina State University in Raleigh has argued that a potent neurotoxin from the dinoflagellate Pfiesteria has killed more than a billion fish in East Coast estuaries and sickened lab workers and fishers. However, the toxin has not been identified. This past summer, doubts escalated when researchers at the Virginia Institute of Marine Science (VIMS) in Gloucester Point and other universities reported in two top journals that they could not find a toxin, and that Pfiesteria can kill larval fish by feeding on them ( Science , 11 October, p. [346][1]). ![Figure][2] Toxic or just hungry? Scientists disagree on how deadly a sugarlike molecule reportedly made by the Pfiesteria microbe (above) is to fish. CREDIT: VIRGINIA INSTITUTE OF MARINE SCIENCE Last week, at the 10th International Conference on Harmful Algae in St. Petersburg, Florida, Burkholder said that her critics had not established the right conditions for making Pfiesteria produce toxin. Her lab coaxed the strain of Pfiesteria shumwayae used in the VIMS experiments to kill juvenile tilapia in less than 4 hours, which meets her criteria for toxicity. Collaborating chemist Peter Mueller of the National Oceanic and Atmospheric Administration in Charleston, South Carolina, described a toxic chemical isolated from Burkholder's fish-killing Pfiesteria strains. Burkholder says the NOAA lab also detected this chemical in water and cells from the VIMS strain. It appears to be a glycoside, a molecule that's half sugar, half some other chemical group that hasn't been identified. Other algal toxin researchers remain skeptical. Wayne Carmichael of Wright State University in Dayton, Ohio, says that, although he knows of one other algal toxin that's a glycoside, this kind is unlikely to cause the neurotoxic effects reported in fish and humans. “It would not explain the range” of observations, he says. VIMS fish pathologist Wolfgang Vogelbein points out that nobody has yet shown that this purified toxin produces the lesions he sees on fish physically attacked by Pfiesteria. Burkholder's critics want the chance to test her toxic strains. Burkholder, who has long been criticized for not sharing her strains, says that “there were discussions” at the meeting of organizing blind testing of her cultures by other labs, but it's “still in the planning stages.” The key issue, she says, is for other scientists to follow her protocols. [1]: /lookup/doi/10.1126/science.298.5592.346 [2]: pending:yes

Simultaneous measurement of phytoplanktonic primary production, nutrient and light availability along a turbid, eutrophic UK east coast estuary (the Colne Estuary)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 231:1-12 (2002) - doi:10.3354/meps231001 Simultaneous measurement of phytoplanktonic primary production, nutrient and light availability along a turbid, eutrophic UK east coast estuary (the Colne Estuary) Esra Kocum*, Graham J. C. Underwood**, David B. Nedwell Department of Biology, University of Essex, John Tabor Buildings, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom *Present address: Canakkale Onsekiz Mart University, Fen-Ed. Fak., 17100 Canakkale, Turkey **Corresponding author. E-mail: gjcu@essex.ac.uk ABSTRACT: Primary production, algal biomass, light conditions and dissolved inorganic nutrient concentrations were monitored simultaneously along the Colne Estuary, UK for a period of 15 mo. Phytoplanktonic primary production and chlorophyll a (chl a) concentration ranged from 0.64 x 10-3 to 17 µgC l-1 h-1 and 0.5 to 37.5 µg chl a l-1, respectively. Nutrient concentrations decreased along a downstream gradient, with high concentrations of nitrate (564 µM), ammonium (291 µM) and phosphate (52 µM) present at the head of the estuary. Despite high light-attenuation coefficients (mean K = 3.2 m-1), the greatest phytoplankton biomass and primary production were measured at the head of the estuary, where nutrient concentrations were high, and phytoplankton biomass and primary production decreased down the estuarine gradient. Despite year-round high nutrient concentrations, chlorophyll a concentrations and rates of primary production remained below levels reported for bloom formation in similar systems. Comparison of field data with measurements derived from phytoplanktonic P vs E curves showed that simulated in situ rates of surface-water biomass-normalised production (PB) were usually significantly lower than the PBmax values. of the phytoplankton. Therefore phytoplankton primary production in the Colne Estuary was light-limited for most of the year, and increased algal biomass and production towards the head of the estuary (despite high attenuation coefficients) was due to a shallow, well-mixed water column (low Zmix:Zeu [critical mixing ratio]). KEY WORDS: Phytoplankton · Estuary · Primary production · Chlorophyll a · Light-limitation Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 231. Online publication date: April 23, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.