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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
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 between …
Microbial Loop Carbon Cycling In Ocean Environments Studied Using A Simple Steady-State Model, T. R. Anderson, H. W. Ducklow
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) at open ocean sites …
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
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.
Density-Dependent Predation, Habitat Variation, And The Persistence Of Marine Bivalve Prey, Rochelle D. Seitz, Rom Lipcius, Ah Hines, Db Eggleston
Density-Dependent Predation, Habitat Variation, And The Persistence Of Marine Bivalve Prey, Rochelle D. 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 …
Variation In Top-Down And Bottom-Up Control Of Marine Bivalves At Differing Spatial Scales, Rochelle D. Seitz, Rom Lipcius
Variation In Top-Down And Bottom-Up Control Of Marine Bivalves At Differing Spatial Scales, Rochelle D. 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, …
Aerobic Respiratory Costs Of Swimming In The Negatively Buoyant Brief Squid Lolliguncula Brevis, Ian K. Bartol, Roger L. Mann, Mark R. Patterson
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, DML …
Grazer Diversity, Functional Redundancy, And Productivity In Seagrass Beds: An Experimental Test, Je Duffy, Ks Macdonald, Jm Rhode, Jd Parker
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 …
Plant Species Diversity And Composition: Experimental Effects On Marine Epifaunal Assemblages, Jd Parker, Je Duffy, R J. Orth
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
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
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 …
Nitrogen Cycling Through A Fringing Marsh-Aquifer Ecotone, Cr Tobias, Iris C. Anderson, Elizabeth A. Canuel, Sa Macko
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 and …
Swimming Mechanics And Behavior Of The Shallow-Water Brief Squid Lolliguncula Brevis, Ian K. Bartol, Mark R. Patterson, Roger L. Mann
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 …