Showing papers by "National Ocean Service published in 2001"

Acetylcholinesterase inhibition in estuarine fish and invertebrates as an indicator of organophosphorus insecticide exposure and effects

Abstract: The majority of insecticides currently in use are organophosphorus, carbamate, and synthetic pyrethroid compounds. Organophosphorus insecticides (OPs) produce toxicity by inhibiting the cholinesterase enzymes in the nervous system. Monitoring of acetylcholinesterase (AChE) inhibition has been widely used in terrestrial and freshwater aquatic systems as an indicator of OP exposure and effects. This review describes the use of AChE inhibition as a biomarker in the estuarine environment, discusses the relationship between AChE inhibition and other manifestations of OP toxicity, and highlights areas where additional research is needed. A variety of studies with estuarine fish have suggested that brain AChE inhibition levels of > 70% are associated with mortality in most species. Selected species, however, appear capable of tolerating much higher levels (> 90%) of brain inhibition. Sublethal effects on stamina have been reported for some estuarine fish in association with brain AChE inhibition levels as low as 50%. Most studies suggest, however, that these effects are observed only when brain AChE inhibition is at near-lethal levels. A number of field studies have successfully used AChE inhibition in fish as a biomarker in the estuarine environment. The use of AChE inhibition as a biomarker in estuarine invertebrates has been less well studied. Although AChE inhibition has been measured in the tissues of a variety of invertebrate species following OP exposure, the relationship between AChE inhibition and lethality is less distinct. Additional work is needed in both fish and invertebrates to better explain species-specific differences in the relationship between AChE inhibition and mortality and to investigate other physiological perturbations associated with AChE inhibition.

Cascading of habitat degradation: Oyster reefs invaded by refugee fishes escaping stress

Abstract: Mobile consumers have potential to cause a cascading of habitat degradation beyond the region that is directly stressed, by concentrating in refuges where they intensify biological interactions and can deplete prey resources. We tested this hypothesis on structurally complex, species-rich biogenic reefs created by the eastern oyster, Crassostrea virginica, in the Neuse River estuary, North Carolina, USA. We (1) sampled fishes and invertebrates on natural and restored reefs and on sand bottom to compare fish utilization of these different habitats and to characterize the trophic relations among large reef-associated fishes and benthic invertebrates, and (2) tested whether bottom-water hypoxia and fishery-caused degradation of reef habitat combine to induce mass emigration of fish that then modify community composition in refuges across an estuarine seascape. Experimentally restored oyster reefs of two heights (1 m tall “degraded” or 2 m tall “natural” reefs) were constructed at 3 and 6 m depths. We sampled...

Applications of Satellite Ocean Color Sensors for Monitoring and Predicting Harmful Algal Blooms

Abstract: The new satellite ocean color sensors offer a means of detecting and monitoring algal blooms in the ocean and coastal zone. Beginning with SeaWiFS (Sea Wide Field-of-view Sensor) in September 1997, these sensors provide coverage every 1 to 2 days with 1-km pixel view at nadir. Atmospheric correction algorithms designed for the coastal zone combined with regional chlorophyll algorithms can provide good and reproducible estimates of chlorophyll, providing the means of monitoring various algal blooms. Harmful algal blooms (HABs) caused by Karenia brevis in the Gulf of Mexico are particularly amenable to remote observation. The Gulf of Mexico has relatively clear water and K. brevis, in bloom conditions, tends to produce a major portion of the phytoplankton biomass. A monitoring program has begun in the Gulf of Mexico that integrates field data from state monitoring programs with satellite imagery, providing an improved capability for the monitoring of K. brevis blooms.

Health and Ecological Impacts of Harmful Algal Blooms: Risk Assessment Needs

Abstract: The symposium session, Indicators for Effects and Predictions of Harmful Algal Blooms, explored the current state of indicators used to assess the human health and ecological risks caused by harmful algal blooms, and highlighted future needs and impediments that must be overcome in order to provide a complete risk assessment of their impacts. Six recognized human poisoning syndromes resulting from algal toxins (paralytic, neurotoxic, amnesic, diarrhetic shellfish poisonings, ciguatera fish poisoning, and putative estuary associated syndrome) impact human health through consumption of contaminated seafood, direct contact with bloom water, or inhalation of aerosolized toxin. Thorough health risk assessment for the variety of algal toxins is hampered to varying degrees because either the toxin has not been identified or indicators for exposure and effects remain poorly defined. Predicting the occurrence and determining the impacts of harmful algal blooms in coastal ecosystems are the two major ecological ris...

Sexual dimorphism of brain aromatase activity in medaka: induction of a female phenotype by estradiol.

Abstract: In this study we identified sex-dependent dimorphism of brain aromatase in the teleost medaka and examined its regulation by sex steriods. We first investigated differential distribution of brain aromatase activity in sexually mature male and female medaka in serial coronal sections of the brain and identified the hypothalamic nuclei contained in each section using the brain atlas of medaka. In the brain of male medaka, high levels of activity are localized in sections containing the preoptic (POA) and suprachiasmatic nuclei (SC) (63-75 fmol/hr) and low levels in the nuclei periventricular dorsalis (HD), ventralis (HV), and caudalis (Hc), nuclei diffusus of lobulus inferiores (NDIL), and nuclei tuberi anteriores (TA) and posteriores (TP) (< 25 fmol/hr). In the brain of female medaka high aromatase activity is localized in sections containing the HD, HV, Hc, NDIL, TA, and TP (85-80 fmol/hr) and highly variable levels in the POA and SC (23-70 fmol/hr). The concentration and time dependency of the exposure of male medaka to estradiol on the total brain aromatase activity and morphologic sex characteristics were determined next. Estradiol increased the activity of brain aromatase in a concentration-dependent manner at 2.5 and 25 microg/L, but the increase was lower at higher concentrations of the hormone. The effect was time dependent, gradually increasing up to the fifth day of exposure, after which it reached a plateau. Estradiol induction of brain aromatase analyzed using Lineweaver-Burke plots of saturation assays revealed a non-first-order reaction. The results indicate that a positive feedback mechanism regulates brain aromatase and imply that the sexual dimorphic distribution of aromatase may be highly sensitive to physiologic cues and environmental perturbations in fish.

Predictive mapping for management and conservation of seagrass beds in North Carolina

Abstract: An Erratum has been published for this article in Aquatic Conservation: Marine and Freshwater Ecosystems 12(2), 2002 577 1 This research extends techniques of predictive mapping from their application in terrestrial environments to marine landscapes by investigating the relationship between seagrass and hydrodynamics in Core Sound, North Carolina, USA 2 An empirically derived logistic multiple regression model and a Boolean logic suitability model were used to produce several predictive map products, including: susceptibility of seagrasses to storms, probability of seagrass cover, and suitability of areas for restoration of seagrasses A visual comparison between these maps and conventional seagrass polygon maps allows for a discussion of ‘field’ versus ‘object’ mapping, and the ramifications for management based on different cartographic techniques 3 The predictive method used here showed that only a small portion (19%) of the seagrass bed in the study area would be expected to have a high probability of seagrass coverage The majority of the seagrass habitat in the study area was predicted to have less than 50% probability of seagrass cover In addition, 16% of the nearly 2000 ha of seagrass within the study area were predicted to be highly susceptible to acute storm events Moreover, using a conservative set of site selection criteria, only 7% of the study area encompassed by seagrass habitat was predicted to have a high probability of successful restoration if injured 4 This method provides for an inexpensive way to scale-up from high-resolution data to a coarser scale that is often required for conservation and management Copyright © 2001 John Wiley & Sons, Ltd

Springtime ichthyoplankton of the slope region off the north-eastern United States of America : larval assemblages, relation to hydrography and implications for larval transport

Abstract: Larval transport in the slope region off north-eastern North America influences recruitment to juvenile habitats for a variety of fishes that inhabit the continental shelf. In this study, collections of larval fishes were made during springtime over the continental slope to provide insights into larval distributions and transport. Ichthyoplankton composition and distribution mirrored the physical complexity of the region. Three larval fish assemblages were defined, each with different water mass distributions. A Gulf Stream assemblage was found predominantly in the Gulf Stream and associated with filaments of discharged Gulf Stream water in the Slope Sea. Larvae of this assemblage originated from oceanic and shelf regions south of Cape Hatteras. Several members of this assemblage utilize habitats in the Middle Atlantic Bight (MAB) as juveniles (Pomatomus saltatrix, Peprilus triacanthus) and other members of the assemblage may share this life cycle (Mugil curema, Sphyraena borealis, Urophycis regia). A Slope Sea assemblage was found in all water masses, and was composed of epi- and mesopelagic fish larvae, as well as larvae of benthic shelf/slope residents. Larvae of one member of this assemblage (U. tenuis) are spawned in the Slope Sea but cross the shelf-slope front and use nearshore habitats for juvenile nurseries. A MAB shelf assemblage was found in MAB shelf water and was composed of larvae that were spawned on the shelf. Some of these species may cross into the Slope Sea before returning to MAB shelf habitats (e.g. Enchelyopus cimbrius, Glyptocephalus cynoglossus). Previous studies have examined the effect of warm-core rings on larval distributions, but this study identifies the importance of smaller-scale features of the MAB shelf/slope front and of filaments associated with Gulf Stream meanders. In combination with these advective processes, the dynamic nature of larval distributions in the Slope Sea appears to be influenced, to varying degrees, by both vertical and horizontal behaviour of larvae and pelagic juveniles themselves.

Two novel alphaherpesviruses associated with fatal disseminated infections in atlantic bottlenose dolphins

Abstract: Two immature female bottlenose dolphins (Tursiops truncatus) were found stranded on the Atlantic coast of the USA. Necropsy and histopathologic examination of both dolphins demonstrated acute necrotizing lesions in multiple organ systems. Commonly seen in these lesions were cells with enlarged nuclei that contained single 4 to 6 μm diameter homogeneous eosinophilic inclusion bodies that were often surrounded by a clear halo. Ultrastructural examination revealed that intranuclear inclusions contained 90 to 110 nm diameter viral particles with electron-dense cores and hexagonal profiles. Viral particles were also present in the cytoplasm, and these were surrounded by variably electron-dense envelopes. Enveloped virions were 140 nm in diameter. Polymerase chain reactions targeting the DNA polymerase and terminase genes of herpesviruses were carried out on unfixed tissues of both animals, and analysis of the DNA products indicated the presence of two novel alphaherpesviruses. The gross, histologic, ultrastruc...

Review and Assessment of In Vitro Detection Methods for Algal Toxins

Abstract: Algal toxins produced by marine and freshwater microalgae present a significant analytical challenge because of their complex structures and frequent occurrence as mixtures of structural congeners, which differ in toxic potencies and are present at varying proportions in contaminated samples Rapid, sensitive in vitro detection methods specific for each class of algal toxins have been developed over the past decade, including immunoassays, enzyme inhibition assays, receptor assays, and cell assays This review discusses the conceptual approaches to assay development and provides a detailed assessment of the use of in vitro detection methods for marine and freshwater algal toxins

Analysis of pesticide runoff from mid-Texas estuaries and risk assessment implications for marine phytoplankton.

Abstract: During 1993, estuarine surface water samples were collected from the mid-Texas coast (Corpus Christi to Port Lavaca, TX). Agricultural watershed areas as well as tidal creeks immediately downstream were chosen as sampling sites along with adjoining bay sampling stations. Collections were made throughout the growing season (February to October 1993) before and after periods of significant (>1.25 cm) rainfall. All samples were initially screened for the presence of pesticides using enzyme-linked immunosorbent assay (ELISA) test kits (EnviroGard™) for triazine herbicides and carbamate insecticides. All samples were extracted and then analyzed using gas chromatography (GC) for quantification of atrazine. Only samples testing positive for carbamate insecticides via ELISA were further extracted for GC analysis to quantify aldicarb and carbofuran. Additionally, laboratory toxicity tests using phytoplankton were examined from published, peer-reviewed literature and compared with the atrazine field levels found in...

Otolith record of age, growth, and ontogeny in larval and pelagic juvenile Stephanolepishispidus (Pisces: Monacanthidae)

Abstract: Juveniles of the planehead filefish Stephano-lepishispidus (Pisces: Monacanthidae) (Linnaeus, 1766) are a major component of the Sargassum spp. community, yet little is known of their ecology. In this study, the otolith record of age, growth, and ontogeny in S.hispidus was examined. Juveniles caught off Beaufort Inlet, North Carolina (USA) on 30 June 1996 were marked with alizarin complexone and reared in a flow-through, outdoor tank for up to 19 days. Examination of marked otoliths at several time intervals showed that increment formation was not significantly different than one increment per day, and thus, increment number was used to estimate age. Depth-distribution, morphology, and meristics of larvae and juveniles collected (1990–1992) between Cape Romain, South Carolina, and Cape Hatteras, North Carolina, were examined to identify the timing of the larval to juvenile transition. All indicators suggested the transition occurred between 17 and 20 days. Mean otolith increment widths exhibited a marked change at about 20 days, coinciding with the timing of the larval to juvenile transition and a change in the depth distribution from bottom to surface waters. Increment width of individual juveniles, however, did not exhibit the same pattern; only 40% conformed to the pattern identified for all fish. Thus, the record of the larval to juvenile transition is clear at the population level, but unresolved at the individual level.

Comparison of the Development and Function of the Swimbladder of Brevoortia tyrannus (Clupeidae) and Leiostomus xanthurus (Sciaenidae)

Abstract: The swimbladders of physostomous Brevoortia tyrannus (Atlantic menhaden) and physoclistous Leiostomus xanthurus (spot) develop as a simple evagination of the larval foregut. The swimbladder of L. xanthurus develops earlier (at yolk and oil globule depletion when larvae are two days posthatch and ∼2 mm notochord length) than it does in B. tyrannus (well after yolk and oil depletion when larvae are 12 days and ∼8 mm). The larvae of each species initially inflate the swimbladder by ascending to the surface and forcing atmospheric gas through a pneumatic duct into the swimbladder lumen. Larval B. tyrannus modulate swimbladder volume and buoyancy within a diel cycle by inflation with atmospheric gas passed through a persistent pneumatic duct and deflation by diffusion through the swimbladder wall along with expulsion through the anus and mouth. This capacity of swimbladder volume modulation and buoyancy compensation corresponds with the average vertical distribution of larvae in the sea, where larval ...

Korotnevella hemistylolepis N. Sp. and Korotnevella monacantholepis N. Sp. (Paramoebidae), Two New Scale-covered Mesohaline Amoebae

Abstract: Two new species of Korotnevella Goodkov, 1988, Korotnevella hemistylolepis n. sp. and Korotnevella monacantholepis n. sp., are described from mesohaline ecosystems. The amoebae are characterized on the basis of light and electron microscopy with special emphasis on the structure of the basket scales, which have species-specific architecture. The two new species are the second and third ones recovered from environments other than freshwater. In terms of scale morphology they most closely resemble a freshwater species, Korotnevella bulla (Schaeffer, 1926) Goodkov, 1988. Two genus names, Dactylamoeba Korotnev, 1880 and Korotnevella Goodkov, 1988, are in current use. The latter name is preferred, pending rediscovery and characterization of Dactylamoeba elongata Korotnev, 1880, the type species of the genus. Korotnevella species can be divided into three groups on the basis of scale morphology, suggesting that the genus may not be monophyletic. A key to species is provided.