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Full-Text Articles in Life Sciences

Temporal Shifts In Top-Down Vs. Bottom-Up Control Of Epiphytic Algae In A Seagrass Ecosystem, Ma Whalen, Je Duffy, Jb Grace Feb 2013

Temporal Shifts In Top-Down Vs. Bottom-Up Control Of Epiphytic Algae In A Seagrass Ecosystem, Ma Whalen, Je Duffy, Jb Grace

VIMS Articles

In coastal marine food webs, small invertebrate herbivores (mesograzers) have long been hypothesized to occupy an important position facilitating dominance of habitat-forming macrophytes by grazing competitively superior epiphytic algae. Because of the difficulty of manipulating mesograzers in the field, however, their impacts on community organization have rarely been rigorously documented. Understanding mesograzer impacts has taken on increased urgency in seagrass systems due to declines in seagrasses globally, caused in part by widespread eutrophication favoring seagrass overgrowth by faster-growing algae. Using cage-free field experiments in two seasons (fall and summer), we present experimental confirmation that mesograzer reduction and nutrients can promote ...


Seasonal Distributions And Movements Of Longnose Gar (Lepisosteus Osseus) Within The York River System, Virginia, Patrick E. Mcgrath, Eric J. Hilton, John A. Musick Jan 2012

Seasonal Distributions And Movements Of Longnose Gar (Lepisosteus Osseus) Within The York River System, Virginia, Patrick E. Mcgrath, Eric J. Hilton, John A. Musick

VIMS Articles

The seasonal movements of Lepisosteus osseus (Longnose Gar) are largely unknown. The goal of this project was to characterize spawning movements and seasonal distributions by using acoustic tagging methods and examining historical catch records from a trawl survey. This is the first time that movements have been studied for an estuarine population of Longnose Gar. Two individuals moved greater minimum distances (69 and 74 km) than found in the only other report on movement in this species. Spawning-ground residency time, collected from two tagged Longnose Gar, was approximately one month, and tidal periodicity was observed for one of the two ...


Carbon Cycling In A Tidal Freshwater Marsh Ecosystem: A Carbon Gas Flux Study, Sc Neubauer, Wd Miller, Iris C. Anderson Jan 2000

Carbon Cycling In A Tidal Freshwater Marsh Ecosystem: A Carbon Gas Flux Study, Sc Neubauer, Wd Miller, Iris C. Anderson

VIMS Articles

A process-based carbon gas flux model was developed to calculate total macrophyte and microalgal production, and community and belowground respiration, for a Peltandra virginica dominated tidal freshwater marsh in Virginia. The model was based on measured field fluxes of CO2 and CH,, scaled to monthly and annual rates using empirically derived photosynthesis versus irradiance, and respiration versus temperature relationships. Because the gas exchange technique measures whole system gas fluxes and therefore includes turnover and seasonal translocation, estimates of total macrophyte production will be more accurate than those calculated from biomass harvests. One Limitation of the gas flux method is that ...


Rehabilitation Of The Troubled Oyster Industry Of The Lower Chesapeake Bay, William J. Hargis Jr., Dexter S. Haven Jan 1988

Rehabilitation Of The Troubled Oyster Industry Of The Lower Chesapeake Bay, William J. Hargis Jr., Dexter S. Haven

VIMS Articles

After 1885 Virginia's lower Chesapeake Bay system produced more oysters per year than any other area in the United States and remained predominant until 1960. Since then she has surrendered supremacy as annual harvests of her troubled oyster industry have steadily declined. Numerous factors were responsible for the tremendous productivity of the lower Bay's oyster beds; a number have been involved in its decline. Natural events, such as the catastrophic epizootics of the early 1960's, continuing disease and predation, increased salinities of drought years and great freshets of tropical storms have contributed significantly to the reduction. Pollution ...


Rhynchocoela: Nemerteans From Marine And Estuarine Waters In Virginia, William E. Mccaul Oct 1963

Rhynchocoela: Nemerteans From Marine And Estuarine Waters In Virginia, William E. Mccaul

VIMS Articles

This paper presents twenty-two species of nemerteans collected from various habitats in the York River, the Chesapeake Bay, and the Eastern Shore of Virginia during the summer of l962. For the presentation of supplementary descriptions, this number includes those already reported from the Chesapeake area (Ferguson and Jones, 1949) , besides seventeen species not previously reported from this region and two newly described species.