Ecology and Evolutionary Biology Commons^™

Report Of Significant Findings--Las Vegas Bay/Boulder Basin Investigations, James F. Labounty, Michael Horn, Bureau Of Reclamation

Publications (WR)

Field sampling was carried out between 0830 and 1500 beginning at the confluence of Las Vegas Wash and the Inner Las Vegas Bay. Ten (10) locations were sampled, each in a similar manner. Locations of sampling stations are in line from the Wash-Bay confluence to a point midway between Saddle and Black Islands. In addition, sampling was done at a location midway between Sentinel Island and the base of Fortification Hill, and at the buoy line in front of Hoover Dam. Sampling stations are labeled from LV01, at Wash-Bay confluence, to LV17 at Hoover Dam. A significant data collection point …

Modeling The Vertical Distribution Of Oyster Larvae In Response To Environmental Conditions, Margaret M. Dekshenieks, Eileen E. Hofmann, John M. Klinck, Eric N. Powell

CCPO Publications

A size-structured, time and vertically-dependent model was used to investigate the effects of water column structure on the distribution of larvae of the oyster Crassostrea virginica. Formulations used to model larval growth and behavior are based upon laboratory studies. Simulated vertical larval distributions obtained for conditions representative of a well-mixed, partially stratified and strongly stratified water column illustrate the effect that salinity and temperature gradients have on moderating larval swimming and hence on larvae vertical location. For well-mixed conditions, smaller larvae are dispersed throughout most of the water column. For strongly stratified conditions, the smaller-sized larvae cluster within the …

Synthetic Organic Compounds: Las Vegas Wash And Lake Mead, National Water Quality Assessment Program (Nawqa): Nevada Basin And Range

Publications (WR)

The Nevada Basin and Range (NVBR) study unit of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is investigating the status of, trends in, and factors affecting water quality in the Las Vegas area. A principal objective of the investigation is to assess the effects of urbanization on the quality of area water resources.

Las Vegas Wash is the surface-water outlet for the Las Vegas area. The wash transports stormwater runoff, shallow ground-water discharge, and tertiary-treated sewage effluent from the Las Vegas area to Las Vegas Bay of Lake Mead on the Colorado River. Most of the flow—about 96 …

Contributions To The Life History Of Juvenile Blueback Herring (Alosa Aestivalis): Phototactic Behavior And Population Dynamics, Douglas A. Dixon

Dissertations, Theses, and Masters Projects

This research investigated the relationship between juvenile abundance indexes (JAIs) for anadromous blueback herring (Alosa aestivalis) and abiotic factors (river flow and temperature) during the spawning and nursery period in the tidal freshwater areas of James, Pamunkey, Mattaponi, and Rappahannock Rivers in Virginia. Accomplishing this objective required the evaluation of the JAI methodology, specifically the effect of phototactic behavior on diel changes in the surface availability to the pushnet sampling gear, and obtaining population dynamics information (hatch dates, growth, natural mortality) during early life history from otolith microstructure of samples collected in 1991 and 1992. Mean catch-per-unit effort (CPUE) at …

The Role Of Microbial Food Webs In Benthic-Pelagic Coupling In Freshwater And Marine Ecosystems, Adele J. Pile

Dissertations, Theses, and Masters Projects

A majority of carbon in freshwater and marine ecosystems is in the form of ultraplankton, heterotrophic and autotrophic plankton &<&5 &\mu&m including heterotrophic bacteria, Prochlorococcus, cyanobacteria, and autotrophic eucaryotes. However, ultraplankton and subsequently microbial food webs have yet to be incorporated into models of benthic-pelagic coupling despite the preponderance of macroinvertebrates with the capacity to feed on ultraplankton. I have examined the role of microbial food webs in benthic-pelagic coupling in three ecosystems: Lake Baikal, Siberia, Russia; Gulf of Maine, Northwest Atlantic Ocean; and Conch Reef, Florida Keys, USA. Using sponges as a model organism and in situ measurements, I have quantified (1) suspension feeding on ultraplankton and (2) release of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) resulting in direct evidence that benthic macroinvertebrates do occupy the level of primary consumer within the microbial food web. Dual-beam flow cytometry was employed to quantified sponge suspension feeding on five types of ultraplankton: heterotrophic bacteria, Synechococcus-type cyanobacteria, autotrophic picoplankton &<&3 &\mu&m, autotrophic eucaryotes 3-10 &\mu&m, and in marine ecosystems Prochlorococcus. Grazing by the freshwater sponges Baikalospongia intermedia and B. bacilliferia and the boreal marine sponge, Mycale lingua, was unselective for all types of ultraplankton with efficiencies ranging from 63-99%. This is the first time that grazing on Synechococcus-type cyanobacteria and Prochlorococcus by macroinvertebrates has been quantified in freshwater and marine ecosystems. Conversely, the coral reef sponges Ircinia felix and I. strobilina release significant amounts of DIN and DIP as a result of grazing on procaryotic plankton. Using a general model for organism-mediated fluxes, it is conservatively estimated that through active suspension feeding sponges in Lake Baikal retain 1.97 g C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and M. lingua retains 29 mg C day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& while at Conch Reef sponges released 204 &\mu&mol DIN day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}& and 48 &\mu&mol DIP day&\sp{lcub}-1{rcub}& m&\sp{lcub}-2{rcub}&. A majority of the carbon retained at all three locations was from procaryotic cell types suggesting that ultraplankton are an important overlooked component of benthic-pelagic coupling.

The Role Of Epibenthic Predators In Structuring Marine Soft-Bottom Communities Along An Estuarine Gradient, Rochelle D. Seitz

Dissertations, Theses, and Masters Projects

A unifying theory of community regulation in soft-bottom systems remains elusive, despite extensive field studies on factors controlling community structure. Here, I have (1) reviewed models of community regulation, (2) examined the role of predation in controlling benthic diversity along a salinity gradient, (3) examined effects of predation upon an abundant bivalve, Macoma balthica, and (4) revised a model of community regulation in an estuarine soft-bottom system. The Menge and Sutherland (MS) "consumer stress model" posits that consumers feed ineffectively in harsh environments, and the importance of physical disturbance, competition and predation varies with recruitment, environmental conditions, and trophic position. …