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VIMS Articles

2001

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Full-Text Articles in Life Sciences

Population Biology And Secondary Production Of The Suspension Feeding Polychaete Chaetopterus Cf. Variopedatus: Implications For Benthic-Pelagic Coupling In Lower Chesapeake Bay, Ml Thompson, Linda C. Schaffner Dec 2001

Population Biology And Secondary Production Of The Suspension Feeding Polychaete Chaetopterus Cf. Variopedatus: Implications For Benthic-Pelagic Coupling In Lower Chesapeake Bay, Ml Thompson, Linda C. Schaffner

VIMS Articles

Benthic suspension feeders are functionally important components of many shallow estuarine and coastal ecosystems. Their relative importance in material and energy cycling depends on physical and biological factors, of which population dynamics of individual species are a key feature, We studied the demographics and secondary production of a population of the tubicolous, suspension feeding polychaete, Chaetopterus cf. variopedatus, of southern Chesapeake Bay, Virginia, to better understand its functional role in an estuarine ecosystem. Average worm densities in the study region ranged from 30 to > 1000 individuals m(-2) and were greatest after the summer recruitment period. Recruitment success varied threefold ...


Microbial Loop Carbon Cycling In Ocean Environments Studied Using A Simple Steady-State Model, T. R. Anderson, H. W. Ducklow Oct 2001

Microbial Loop Carbon Cycling In Ocean Environments Studied Using A Simple Steady-State Model, T. R. Anderson, H. W. Ducklow

VIMS Articles

A simple steady-state model is used to examine the microbial loop as a pathway for organic C in marine systems, constrained by observed estimates of bacterial to primary production ratio (BP:PP) and bacterial growth efficiency (BGE). Carbon sources (primary production including extracellular release of dissolved organic carbon, DOC), cycling via zooplankton grazing and viral lysis, and sinks (bacterial and zooplankton respiration) are represented. Model solutions indicate that, at least under near steady-state conditions, recent estimates of BP:PP of about 0.1 to 0.15 are consistent with reasonable scenarios of C cycling (low BGE and phytoplankton extracellular release ...


Density-Dependent Predation, Habitat Variation, And The Persistence Of Marine Bivalve Prey, Rd Seitz, Rom Lipcius, Ah Hines, Db Eggleston Aug 2001

Density-Dependent Predation, Habitat Variation, And The Persistence Of Marine Bivalve Prey, Rd Seitz, Rom Lipcius, Ah Hines, Db Eggleston

VIMS Articles

The persistence of prey encountering intense predation varies by species, prey density, and habitat type; however, the collective impact of these factors has rarely been tested experimentally in natural marine systems. Using the thin-shelled clams Mya arenaria and Macoma balthica as prey, and the main epibenthic predator of whole adult clams, the blue crab Callinectes sapidus, we conducted a series of experiments in Chesapeake Bay tributaries that (1) links field abundance and distribution of bivalve prey species with habitat-specific mortality patterns; (2) represents the first comprehensive field test of species-specific, habitat-specific, and density-dependent mortality for subtidal, soft-bottom, deep-burrowing prey; and ...


The Identification, Conservation, And Management Of Estuarine And Marine Nurseries For Fish And Invertebrates: A Better Understanding Of The Habitats That Serve As Nurseries For Marine Species And The Factors That Create Site-Specific Variability In Nursery Quality Will Improve Conservation And Management Of These Areas, Michael W. Beck, Kl Heck, Kenneth W. Able, Daniel L. Childers, David B. Eggleston, Bronwyn M. Gillanders, Benjamin Halpern, Cynthia G. Hays, Kaho Hoshino, Thomas J. Minello, R J. Orth, Peter F. Sheridan, Michael P. Weinstein Aug 2001

The Identification, Conservation, And Management Of Estuarine And Marine Nurseries For Fish And Invertebrates: A Better Understanding Of The Habitats That Serve As Nurseries For Marine Species And The Factors That Create Site-Specific Variability In Nursery Quality Will Improve Conservation And Management Of These Areas, Michael W. Beck, Kl Heck, Kenneth W. Able, Daniel L. Childers, David B. Eggleston, Bronwyn M. Gillanders, Benjamin Halpern, Cynthia G. Hays, Kaho Hoshino, Thomas J. Minello, R J. Orth, Peter F. Sheridan, Michael P. Weinstein

VIMS Articles

No abstract provided.


Habitat Fragmentation In A Seagrass Landscape: Patch Size And Complexity Control Blue Crab Survival, Ka Hovel, Rom Lipcius Jul 2001

Habitat Fragmentation In A Seagrass Landscape: Patch Size And Complexity Control Blue Crab Survival, Ka Hovel, Rom Lipcius

VIMS Articles

Habitat fragmentation is increasingly common on land and in the sea, leading to small, isolated habitat patches in which ecological processes may differ substantially from those in larger, continuous habitats. Seagrass is a productive but fragmented subtidal habitat that serves as a refuge from predation for many animals because its structural complexity limits the detection and capture of resident prey. The singular influence of seagrass habitat fragmentation (e.g., patch size) on faunal survival is largely unknown and has been difficult to quantify because seagrass habitat complexity (e.g., shoot density) and patch size are often confounded and vary seasonally ...


Variation In Top-Down And Bottom-Up Control Of Marine Bivalves At Differing Spatial Scales, Rd Seitz, Rom Lipcius Jun 2001

Variation In Top-Down And Bottom-Up Control Of Marine Bivalves At Differing Spatial Scales, Rd Seitz, Rom Lipcius

VIMS Articles

At large spatial scales(> 1 km). the forces structuring marine communities are diverse and include oceanographic, geological. and human processes, as well as availability of regional species pools. Few studies in marine and estuarine systems have examined the joint effects of predation (top-down) and food availability (bottom-up) in controlling populations at these scales. We compared the relative influence of top-down and bottom-up factors to population abundance of the infaunal clam Macomala balthican in two ecosystems differing in spatial extent by an order of magnitude. the York River, 50 km long, and the Rhode River. 5 km long. In both rivers ...


Reduction In Dna Binding Activity Of The Transcription Factor Pax-5a In B Lymphocytes Of Aged Mice, J Anspach, G Poulsen, I Kaattari, R Pollock, P Zwollo Jan 2001

Reduction In Dna Binding Activity Of The Transcription Factor Pax-5a In B Lymphocytes Of Aged Mice, J Anspach, G Poulsen, I Kaattari, R Pollock, P Zwollo

VIMS Articles

Aging has been associated with intrinsic changes of the humoral immune response, which may lead to an increased occurrence of autoimmune disorders and pathogenic susceptibility. The transcription factor Pax-5 is a key regulator of B cell development. Pax-5a/B cell-specific activator protein and an alternatively spliced isoform, Pax-Sd, may have opposing functions in transcriptional regulation due to the lack of a transactivation domain in Pax-Sd. To study B cell-specific changes that occur during the aging process, we investigated expression patterns of Pax-Sa and Sd in mature B cells of young and aged mice. RNase protection assays showed a similar transcriptional ...


A Comparative Field Study Of Crassostrea Ariakensis (Fujita 1913) And Crassostrea Virginica (Gmelin 1791) In Relation To Salinity In Virginia, G. W. Calvo, Mark Luckenbach, Standish K. Allen Jr., E. M. Burreson Jan 2001

A Comparative Field Study Of Crassostrea Ariakensis (Fujita 1913) And Crassostrea Virginica (Gmelin 1791) In Relation To Salinity In Virginia, G. W. Calvo, Mark Luckenbach, Standish K. Allen Jr., E. M. Burreson

VIMS Articles

We examined survival, growth, and disease susceptibility of triploid Crassostrea ariakensis (= rivularis) and compared results with that of diploid Crassostrea virginica. Two hundred and fifty oysters (age = 2 yr, mean shell height = 60-64 mm) of each species were deployed at duplicate sites, (Chesapeake Bay, and the Atlantic Coast of Virginia) within low, medium, and high salinity regimes respectively (< 15%, 15-25%, > 25%). Over the course of the study, from June 1998 to September 1999, C. virginica exhibited low survival, modest growth and high disease susceptibility. In contrast, C. ariakensis exhibited high survival, high growth rate, and low disease susceptibility. At low salinity sites ...


Grazer Diversity, Functional Redundancy, And Productivity In Seagrass Beds: An Experimental Test, Je Duffy, Ks Macdonald, Jm Rhode, Jd Parker Jan 2001

Grazer Diversity, Functional Redundancy, And Productivity In Seagrass Beds: An Experimental Test, Je Duffy, Ks Macdonald, Jm Rhode, Jd Parker

VIMS Articles

Concern over the accelerating loss of biodiversity has stimulated renewed interest in relationships among species richness, species composition, and the functional properties of ecosystems. Mechanistically, the degree of functional differentiation or complementarity among individual species determines the form of such relationships and is thus important to distinguishing among alternative hypotheses for the effects of diversity on ecosystem processes. Although a growing number of studies have reported relationships between plant diversity and ecosystem processes, few have explicitly addressed how functional diversity at higher trophic levels influences ecosystem processes. We used mesocosm experiments to test the impacts of three herbivorous crustacean species ...


The Effects Of A Regulatory Gear Restriction On The Recruiting Year Class In The Sea Scallop, Placopecten Magellanicus (Gmelin, 1791), Fishery, Jc Brust, Wd Dupaul, Je Kirkley Jan 2001

The Effects Of A Regulatory Gear Restriction On The Recruiting Year Class In The Sea Scallop, Placopecten Magellanicus (Gmelin, 1791), Fishery, Jc Brust, Wd Dupaul, Je Kirkley

VIMS Articles

In 1994, Amendment 4 to the sea scallop (Placopecten magellanicus) fishery management plan was adopted, which restricted fishing effort by controlling vessel days at sea. crew size, and gear size. Dredge ring size was increased from 76.2 mm (3.0") to 82.6 mm (3.25") in March 1994, and again to 88.9 mm (3.5") in January 1996 to increase the age of entry of scallops into the fishery. Between June 1994 and April 1995, four trips were taken on commercial scallop vessels in the western mid-Atlantic to determine harvest efficiency of 88.9-mm dredge rings relative ...


Development And Verification Of A Model For The Population Dynamics Of The Protistan Parasite, Perkinsus Marinus, Within Its Host, The Eastern Oyster, Crassostrea Virginica, In Chesapeake Bay, Lmr Calvo, Rl Wetzel, Em Burreson Jan 2001

Development And Verification Of A Model For The Population Dynamics Of The Protistan Parasite, Perkinsus Marinus, Within Its Host, The Eastern Oyster, Crassostrea Virginica, In Chesapeake Bay, Lmr Calvo, Rl Wetzel, Em Burreson

VIMS Articles

A simulation model was developed to investigate the population dynamics of the protistan parasite, Perkinsus marinus, within its host, the eastern oyster, Crassostrea virginica. The main objective was to evaluate the relationship between P. marinus population dynamics and environmental conditions in order to predict the onset and termination of P. marinus epizootics in Chesapeake Bay oyster populations. Information derived from laboratory experiments and from direct field observations of P. marinus dynamics in the James River for the years 1990 to 1993 was utilized for model development. The individual-based model, which is driven by temperature and salinity, tracks the average within-host ...


A Comparison Of Calcified Structures For Aging Summer Flounder, Paralichthys Dentatus, Ann M. Sipe, Mark E. Chittenden Jan 2001

A Comparison Of Calcified Structures For Aging Summer Flounder, Paralichthys Dentatus, Ann M. Sipe, Mark E. Chittenden

VIMS Articles

Calcified structures of summer flounder, Paralichthys dentatus, were evaluated to identify the best age determination method. Scales, the currently preferred structure, were compared with opercular bones and to right and left whole and sectioned otoliths for ages 0 to 10. All structures showed concentric rings that were interpreted as annual; however structures differed greatly in the clarity of their presumed annual marks. Right and left otoliths generally gave the same age, although they differed in the clarity of marks. Sectioned otoliths, particularly right ones, were the best aging structure. Right sectioned otoliths consistently showed the clearest marks and had the ...


Nitrogen Cycling Through A Fringing Marsh-Aquifer Ecotone, Cr Tobias, Iris C. Anderson, Elizabeth A. Canuel, Sa Macko Jan 2001

Nitrogen Cycling Through A Fringing Marsh-Aquifer Ecotone, Cr Tobias, Iris C. Anderson, Elizabeth A. Canuel, Sa Macko

VIMS Articles

Fringing wetlands are critical components of estuarine systems, and subject to water fluxes from both watersheds and estuaries. To assess the effect of groundwater discharge on marsh nitrogen cycling, we measured N-cycling in sediments from a fringing mesohaline marsh in Virginia which receives a seasonal groundwater input. Mineralization, nitrification, potential denitrification (DNF), and potential dissimilatory nitrate reduction to ammonium (DNRA) rates were estimated along with porewater concentrations of oxygen, sulfide, and conductivity during high (May 1997) and low (October 1997) groundwater discharge. All N-cycling processes were confined to the upper 1 to 1.5 m of marsh, where organic matter ...


Modeling The Response Of Top-Down Control Exerted By Gelatinous Carnivores On The Black Sea Pelagic Food Web, Temel Oguz, Hugh W. Ducklow, Jennifer E. Purcell, Paola Malanotte-Rizzoli Jan 2001

Modeling The Response Of Top-Down Control Exerted By Gelatinous Carnivores On The Black Sea Pelagic Food Web, Temel Oguz, Hugh W. Ducklow, Jennifer E. Purcell, Paola Malanotte-Rizzoli

VIMS Articles

Recent changes in structure and functioning of the interior Black Sea ecosystem are studied by a series of simulations using a one-dimensional, vertically resolved, coupled physical-biochemical model. The simulations are intended to provide a better understanding of how the pelagic food web structure responds to increasing grazing pressure by gelatinous carnivores (medusae Aurelia aurita and ctenophore Mnemiopsis leidyi) during the past 2 decades. The model is first shown to represent typical eutrophic ecosystem conditions of the late 1970s and early 1980s. This simulation reproduces reasonably well the observed planktonic food web structure at a particular location of the Black Sea ...


Emerging Areas Of Research Reported During The Cdc National Conference On Pfiesteria: From Biology To Public Health, C Rubin, Eugene M. Burreson Jan 2001

Emerging Areas Of Research Reported During The Cdc National Conference On Pfiesteria: From Biology To Public Health, C Rubin, Eugene M. Burreson

VIMS Articles

Since its identification in 1996, the marine dinoflagellate Pfiesteria piscicida Steidinger & Burkholder has been the focus of intense scientific inquiry in disciplines ranging from estuarine ecology to epidemiology and from molecular biology to public health. Despite these research efforts, the extent of human exposure and the degree of human illness directly associated with Pfiesteria is still in the process of being defined. Unfortunately, during this same time Pfiesteria has also stimulated media coverage that in some instances jumped ahead of the science to conclude that Pfiesteria presents a widespread threat to human health. Political and economic forces also came into play when the tourism and seafood industries were adversely impacted by rumors of toxin-laden water in estuaries along the east coast of the United States. Amid this climate of evolving science and public concern, Pfiesteria has emerged as a highly controversial public health issue. In October 2000 Centers for Disease Control and Prevention sponsored the National Conference on Pfiesteria: From Biology to Public Health to bring together Pfiesteria researchers from many disparate disciplines. The goal of this meeting was to describe the state of the science and identify directions for future research. In preparation for the conference an expert peer-review panel was commissioned to review the existing literature and identify research gaps; the summary of their review is published in this monograph. During the meeting primary Pfiesteria researchers presented previously unpublished results. The majority of those presentations are included as peer-reviewed articles in this monograph. The discussion portion of the conference focused upon researcher-identified research gaps. This article details the discussion segments of the conference and makes reference to the presentations as it describes emerging areas of Pfiesteria research.


Classification And Identification Of Pfiesteria And Pfiesteria-Like Species, K Steidinger, Patrice Mason, Kimberly S. Reece, Lw Haas Jan 2001

Classification And Identification Of Pfiesteria And Pfiesteria-Like Species, K Steidinger, Patrice Mason, Kimberly S. Reece, Lw Haas

VIMS Articles

Dinoflagellates can be classified both botanically and zoologically; however, they are typically put in the botanical division Pyrrhophyta. As a group they appear most related to the protistan ciliates and apicomplexans at the ultrastructure level. Within the Pyrrhophyta are both unarmored and armored forms of the dominant, motile flagellated stage. Unarmored dinoflagellates do not have thecal or wall plates arranged in specific series, whereas armored species have plates that vary in thickness but are specific in number and arrangement. In armored dinoflagellates, the plate pattern and tabulation is a diagnostic character at the family, subfamily, and even genus levels. In ...


Skin Ulcers In Estuarine Fishes: A Comparative Pathological Evaluation Of Wild And Laboratory-Exposed Fish, Wolfgang K. Vogelbein, Jeffrey D. Shields, Lw Haas, Kimberly S. Reece, D. E. Zwerner Jan 2001

Skin Ulcers In Estuarine Fishes: A Comparative Pathological Evaluation Of Wild And Laboratory-Exposed Fish, Wolfgang K. Vogelbein, Jeffrey D. Shields, Lw Haas, Kimberly S. Reece, D. E. Zwerner

VIMS Articles

The toxic dinoflagellate Pfiesteria piscicida Steidinger & Burkholder has recently been implicated as the etiologic agent of acute mass mortalities and skin ulcers in menhaden, Brevoortia tyrannus, and other fishes from mid-Atlantic U.S. estuaries. However, evidence for this association is largely circumstantial and controversial. We exposed tilapia (Oreochromis spp.) to Pfiesteria shurnwayae Glasgow & Burkholder (identification based on scanning electron microscopy and molecular analyses) and compared the resulting pathology to the so-called Pfiesteria-specific lesions occurring in wild menhaden. The tilapia challenged by high concentrations (2,000-12,000 cells/mL) of P. shurnwayae exhibited loss of mucus coat and scales plus mild petecchial hemorrhage, but no deeply penetrating chronic ulcers like those in wild menhaden. Histologically, fish exhibited epidermal erosion with bacterial colonization but minimal associated inflammation. In moribund fish, loss of epidermis was widespread over large portions of the body. Similar erosion occurred in the mucosa lining the oral and branchial cavities. Gills exhibited epithelial lifting, loss of secondary lamellar structure, and infiltration by lymphoid cells. Epithelial lining of the lateral line canal LLC) and olfactory organs exhibited severe necrosis. Visceral organs, kidney, and neural tissues (brain, spinal cord, ganglia, peripheral nerves) were histologically normal. An unexpected finding was the numerous P. shurnwayae cells adhering to damaged skin, skin folds, scale pockets, LLC, and olfactory tissues. In contrast, histologic evaluation of skin ulcers in over 200 wild menhaden from Virginia and Maryland portions of the Chesapeake Bay and the Pamlico Estuary, North Carolina, revealed that all ulcers harbored a deeply invasive, highly pathogenic fungus now known to be Aphanomyces invadans. In menhaden the infection always elicited severe myonecrosis and intense granulomatous myositis. The consistent occurrence of this fungus and the nature and severity of the resulting inflammatory response indicate that these ulcers are chronic (age > 1 week) and of an infectious etiology, not the direct result of an acute toxicosis initiated by Pfiesteria toxin(s) as recently hypothesized. The disease therefore is best called ulcerative mycosis (UM). This study indicates that the pathology of Pfiesteria laboratory exposure is fundamentally different from that of UM in menhaden; however, we cannot rule out Pfiesteria as one of many possible early initiators predisposing wild fishes to fungal infection in some circumstances.


A Unique Mycobacterium Species Isolated From An Epizootic Of Striped Bass (Morone Saxatilis), Martha W. Rhodes, Howard Kator, Shaban Kotob, Peter Van Berkum, Ilsa Kaattari, Wolfgang K. Vogelbein, Margaret Floyd, W. Ray Butler, Frederick D. Quinn, Christopher Ottinger, Emmet Shotts Jan 2001

A Unique Mycobacterium Species Isolated From An Epizootic Of Striped Bass (Morone Saxatilis), Martha W. Rhodes, Howard Kator, Shaban Kotob, Peter Van Berkum, Ilsa Kaattari, Wolfgang K. Vogelbein, Margaret Floyd, W. Ray Butler, Frederick D. Quinn, Christopher Ottinger, Emmet Shotts

VIMS Articles

We isolated a Mycobacterium sp. resembling Mycobacterium marinum and M. ulcerans from diseased striped bass (Morone saxatilis) during an epizootic of mycobacteriosis in the Chesapeake Bay. This isolate may represent an undescribed Mycobacterium species, based on phenotypic characteristics and comparative 16S rRNA gene sequence.


Delivery And Fate Of Fluvial Water And Sediment To The Sea: A Marine Geologist's View Of European Rivers, J. D. Milliman Jan 2001

Delivery And Fate Of Fluvial Water And Sediment To The Sea: A Marine Geologist's View Of European Rivers, J. D. Milliman

VIMS Articles

Despite their relatively small drainage areas, European rivers reflect a wide variety of hydrologic regimes, although with very few exceptions they have been strongly affected by human activity. Scandinavian rivers (particularly those draining Iceland and western Norway) can have high runoff, and, except for those draining Iceland, all have very low suspended and dissolved sediment loads. Northern and western European rivers have somewhat lower runoff, among the lowest suspended sediment yields in the world, and anthropogenically enhanced dissolved solid loads. Annual discharge of many of these rivers appears to vary inversely with the North Atlantic Oscillation index. Rivers discharging from ...


Swimming Mechanics And Behavior Of The Shallow-Water Brief Squid Lolliguncula Brevis, Ian K. Bartol, Mark R. Patterson, Roger L. Mann Jan 2001

Swimming Mechanics And Behavior Of The Shallow-Water Brief Squid Lolliguncula Brevis, Ian K. Bartol, Mark R. Patterson, Roger L. Mann

VIMS Articles

Although squid are among the most versatile swimmers and rely on a unique locomotor system, little is known about the swimming mechanics and behavior of most squid, especially those that swim at low speeds in inshore waters. Shallow-water brief squid Lolliguncula brevis, ranging in size from 1.8 to 8.9 cm in dorsal mantle length (DML), were placed in flumes and videotaped, and the data were analyzed using motion-analysis equipment. Flow visualization and force measurement experiments were also performed in water tunnels. Mean critical swimming speeds (Ucrit) ranged from 15.3 to 22.8 cm s–1, and ...


Aerobic Respiratory Costs Of Swimming In The Negatively Buoyant Brief Squid Lolliguncula Brevis, Ian K. Bartol, Roger L. Mann, Mark R. Patterson Jan 2001

Aerobic Respiratory Costs Of Swimming In The Negatively Buoyant Brief Squid Lolliguncula Brevis, Ian K. Bartol, Roger L. Mann, Mark R. Patterson

VIMS Articles

Because of the inherent inefficiency of jet propulsion, squid are considered to be at a competitive disadvantage compared with fishes, which generally depend on forms of undulatory/oscillatory locomotion. Some squid, such as the brief squid Lolliguncula brevis, swim at low speeds in shallow-water complex environments, relying heavily on fin activity. Consequently, their swimming costs may be lower than those of the faster, more pelagic squid studied previously and competitive with those of ecologically relevant fishes. To examine aerobic respiratory swimming costs, O2 consumption rates were measured for L. brevis of various sizes (2–9 cm dorsal mantle length ...


Seasonal Occurrence And Site-Utilization Patterns Of Adult Tautog, Tautoga Onitis (Labridae), At Manmade And Natural Structures In Lower Chesapeake Bay, Michael D. Arendt, Jon Lucy, Thomas A. Munroe Jan 2001

Seasonal Occurrence And Site-Utilization Patterns Of Adult Tautog, Tautoga Onitis (Labridae), At Manmade And Natural Structures In Lower Chesapeake Bay, Michael D. Arendt, Jon Lucy, Thomas A. Munroe

VIMS Articles

Ultrasonic transmitters were surgically implanted into adult tautog (n=27,400-514 mm TL) to document seasonal occurrence and site utilization at four sites situated within known tautog habitat near Cape Charles, Virginia, in lower Chesapeake Bay. Tagged tautog were released at the same sites where originally caught within 2 h of capture. Sites were continuously monitored with automated acoustic receivers between 9 November 1998 and 13 October 1999. Two sites consisted of natural bedform. materials and two sites consisted of manmade materials. Ninety-four percent of tautog (n=15) released in fall 1998 remained inshore during winter at sustained water temperatures ...


Plant Species Diversity And Composition: Experimental Effects On Marine Epifaunal Assemblages, Jd Parker, Je Duffy, R J. Orth Jan 2001

Plant Species Diversity And Composition: Experimental Effects On Marine Epifaunal Assemblages, Jd Parker, Je Duffy, R J. Orth

VIMS Articles

Plant diversity is believed to govern animal community structure, yet few studies have tested this relationship. We manipulated plant species diversity and composition (2 seagrasses and 3 seaweeds) and measured the abundance, diversity, and biomass of plant-associated macroinvertebrates in a temperate, estuarine seagrass community. Animal diversity was weakly but positively related to plant diversity (Simpson's 1 - lambda). Most indices of animal diversity, however, were more strongly related to total plant surface area than to plant diversity. Epifaunal abundance and biomass increased, whereas epifaunal diversity and evenness decreased with total plant surface area. Both food and habitat covary with plant ...


Species-Specific Impacts Of Grazing, Amphipods In An Eelgrass-Bed Community, Je Duffy, Am Harvilicz Jan 2001

Species-Specific Impacts Of Grazing, Amphipods In An Eelgrass-Bed Community, Je Duffy, Am Harvilicz

VIMS Articles

Small, grazing invertebrates often benefit seagrasses by cropping their epiphytic algal competitors. Yet predictive relations between grazer abundance and seagrass performance are elusive, in significant part because of poorly understood diversity in mesograzer feeding biology. We conducted experiments in eelgrass Zostera marina microcosms to explore how differences in feeding between 2 common grazing amphipod taxa affected accumulation and species composition of epiphytes on eelgrass, as well as amphipod population growth, competition and production, over a 4-week period in summer. Gammarus mucronatus and ampithoids (a mixture of Cymadusa compta and Ampithoe longimana) were stocked, singly and in combination, along with a ...


Magnitude And Variability Of Benthic And Pelagic Metabolism In A Temperate Coastal Lagoon, Kj Mcglathery, Iris C. Anderson, Ac Tyler Jan 2001

Magnitude And Variability Of Benthic And Pelagic Metabolism In A Temperate Coastal Lagoon, Kj Mcglathery, Iris C. Anderson, Ac Tyler

VIMS Articles

In shallow coastal systems where most of the seafloor lies within the photic zone, benthic photoautotrophy is likely to play a key role in regulating carbon and nitrogen cycling. We measured dissolved inorganic carbon exchanges in seasonal microcosm incubations to determine the relative importance of benthic (with and without macroalgae) and water column metabolism at 3 sites located along a nutrient gradient in a coastal barrier-island lagoon on the eastern shore of Virginia. When coupled with data on in situ biomass, the incubations clearly indicated a seasonality in the dominance of primary producers at the sites, with benthic primary producers ...


Restoration Of The Oyster Resource In Chesapeake Bay: The Role Of Oyster Reefs In Population Enhancement, Water Quality Improvement And Support Of Diverse Species-Rich Communities, Roger L. Mann Jan 2001

Restoration Of The Oyster Resource In Chesapeake Bay: The Role Of Oyster Reefs In Population Enhancement, Water Quality Improvement And Support Of Diverse Species-Rich Communities, Roger L. Mann

VIMS Articles

Restoration of the oyster Crassostrea virginica resource to the Chesapeake Bay is a widely supported goal. The role of the oyster in restoration through benthic-pelagic coupling is examined in the context of current and projected watershed management problems, agricultural and urban development with associated nutrient and sediment erosion issues, in the entire Chesapeake Bay watershed. Efforts to date have focused on rebuilding three-dimensional reef structures, often with oyster broodstock enhancement, in predominantly small estuaries with retentive circulation to provide demonstration of increased resultant recruitment. Fishery enhancement activity is then based on local increases in recruitment. Such examples are used to ...


Oyster Reefs As Fish Habitat: Opportunistic Use Of Restored Reefs By Transient Fishes, Juliana M. Harding, Roger L. Mann Jan 2001

Oyster Reefs As Fish Habitat: Opportunistic Use Of Restored Reefs By Transient Fishes, Juliana M. Harding, Roger L. Mann

VIMS Articles

Under the Magnuson-Stevenson Fisheries Management Act of 1996, current fisheries management practice is focused on the conce_pt of Essential Fish Habitat (EFH). Application of the EFH concept to estuarine habitats relates directly to ongoing oyster reef restorat10n efforts. Oyster reef restoration typically creates complex habitat in regions where such habitat is limited or absent. While healthy oyster reefs provide structurally and ecologically complex habitat for many other species from all trophic levels including recreationally and commercially valuable transient finfishes, additional data is required to evaluate oyster reef habitats in the context of essential fish habitat. Patterns of transient fish species ...


Criteria For Determining Maturity Stage In Female American Shad, Alosa Sapidissima, And A Proposed Reproductive Cycle, Je Olney, Sc Denny, Jm Hoenig Jan 2001

Criteria For Determining Maturity Stage In Female American Shad, Alosa Sapidissima, And A Proposed Reproductive Cycle, Je Olney, Sc Denny, Jm Hoenig

VIMS Articles

We describe macro- and microscopic criteria to judge maturation stages of female American shad (Alosa sapidissima) collected in the York river, Virginia, USA. For comparison, we also examined ovaries of fishes collected in the Edisto river, South Carolina, and the Connecticut river, Massachusetts. The study augments a developing stock assessment program that is evaluating the use of index-removal and change-in-ratio estimators of exploitation rate and absolute abundance. Samples were obtained from traps at the York river mouth, staked gill nets in mid-reaches of the river, and drift gill nets on the spawning grounds (approximately 100 km from the river mouth ...


Stomach Content Analysis Of Cobia, Rachycentron Canadum, From Lower Chesapeake Bay, Michael D. Arendt, John E. Olney, Jon A. Lucy Jan 2001

Stomach Content Analysis Of Cobia, Rachycentron Canadum, From Lower Chesapeake Bay, Michael D. Arendt, John E. Olney, Jon A. Lucy

VIMS Articles

No abstract provided.


Differential Diagnosis Of Mixed Haplosporidium Costale And Haplosporidium Nelsoni Infections In The Eastern Oyster, Crassostrea Virginica, Using Dna Probes, Na Stokes, Em Burreson Jan 2001

Differential Diagnosis Of Mixed Haplosporidium Costale And Haplosporidium Nelsoni Infections In The Eastern Oyster, Crassostrea Virginica, Using Dna Probes, Na Stokes, Em Burreson

VIMS Articles

Haplosporidium costale and Haplosporidium nelsoni are morphologically similar pathogens of the eastern oyster Crassostrea virginica. In the absence of the spore stage, infections of the two species are extremely difficult, if not impossible, to distinguish using traditional light microscopy of stained tissue sections. Species-specific molecular diagnostics were developed for H. costale from the small subunit ribosomal DNA (SSU rDNA) sequence. The polymerase chain reaction (PCR) primers amplified a 557 base pair (bp) region of the H. costale SSU rDNA, but did not amplify DNA from oyster (C. virginica) or from six other haplosporidans (H. nelsoni, H. louisiana, H. lusitanicum, Minchinia ...