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2004

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Marine Biology

Biological Sciences Peer-Reviewed Articles

Articles 1 - 6 of 6

Full-Text Articles in Life Sciences

Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl Jul 2004

Light Dependence Of [H-3]Leucine Incorporation In The Oligotrophic North Pacific Ocean, Mj Church, Hw Ducklow, Da Karl

VIMS Articles

The influence of irradiance on bacterial incorporation of [H-3] leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [H-3]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [C-14] bicarbonate) in both the upper and lower photic zones. Rates of [H-3]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence ...


Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer Apr 2004

Particle-Associated Flagellates: Swimming Patterns, Colonization Rates, And Grazing On Attached Bacteria, T Kiorboe, Hp Grossart, H Ploug, K Tang, B Auer

VIMS Articles

Some pelagic flagellates colonize particles, such as marine snow, where they graze on bacteria and thus impact the dynamics of the attached microbial communities. Particle colonization is governed by motility. Swimming patterns of 2 particle-associated flagellates, Bodo designis and Spumella sp., are very different, the former swimming slowly in an erratic, random pattern, and the latter faster and along smooth helixes of variable amplitude and frequency. At spatial scales exceeding ca. 50 mum, the motility of B. designis can be described as a random walk and modeled as diffusion. Spumella sp. shows directional persistence of the helical axes up to ...


Seed Production From The Mixed Mating System Of Chesapeake Bay (Usa) Eelgrass (Zostera Marina; Zosteraceae), Jm Rhode, Je Duffy Feb 2004

Seed Production From The Mixed Mating System Of Chesapeake Bay (Usa) Eelgrass (Zostera Marina; Zosteraceae), Jm Rhode, Je Duffy

VIMS Articles

In monoecious plants, gametes can be exchanged in three ways: among unrelated genets (outbreeding), with close relatives (inbreeding), or within individuals (geitonogamous selling). These different mating systems may have consequences for population demography and fitness. The experiment presented herein used artificial crosses to examine the mating system of Chesapeake Bay, Virginia, USA eelgrass (Zostera marina L; Zosteraceae), a bisexual submerged aquatic plant that can outbreed, inbreed, and self. Genetic data indicate severe heterozygosity deficiencies and patchy genotype distribution in these beds, suggesting that plants therein reproduce primarily by vegetative propagation, autogamy, or geitonogamy. To clarify eelgrass reproductive strategies, flowers from ...


Allee Effects In Marine Systems, J Gascoigne, Rn Lipcius Jan 2004

Allee Effects In Marine Systems, J Gascoigne, Rn Lipcius

VIMS Articles

The fitness or population growth rate of populations with Allee effects increases with increasing population size or density up to a certain threshold. Allee effects are possible in marine populations, as they are less open than has been assumed and may have a metapopulation structure. We modelled the population consequences of Allee effects and show that increases in mortality interact with critical Allee thresholds, such that an Allee effect with no population consequences at low mortality can drive a population to extinction when mortality is increased. In heavily fished species, populations with strong Allee effects go extinct at lower levels ...


Production Of Chromophoric Dissolved Organic Matter (Cdom) In The Open Ocean By Zooplankton And The Colonial Cyanobacterium Trichodesmium Spp., Dk Steinberg, Nb Nelson, Ca Carlson, Ac Prusak Jan 2004

Production Of Chromophoric Dissolved Organic Matter (Cdom) In The Open Ocean By Zooplankton And The Colonial Cyanobacterium Trichodesmium Spp., Dk Steinberg, Nb Nelson, Ca Carlson, Ac Prusak

VIMS Articles

Chromophoric (or colored) dissolved organic matter (CDOM) has been identified as a major determinant of the optical properties of oligotrophic oceans. The factors controlling distribution of CDOM far from the direct influence of land are not well known, as CDOM abundance and distribution does not directly correlate with phytoplankton productivity or biomass, or with dissolved organic matter (DOM) concentration. As part of a larger study of the dynamics of CDOM in the open ocean, we investigated direct release from plankton as a factor contributing to distribution patterns of CDOM. We measured the production of CDOM by zooplankton (copepods, euphausiids, amphipods ...


Conserving Populations At Low Abundance: Delayed Functional Maturity And Allee Effects In Reproductive Behaviour Of The Queen Conch Strombus Gigas, J Gascoigne, Rn Lipcius Jan 2004

Conserving Populations At Low Abundance: Delayed Functional Maturity And Allee Effects In Reproductive Behaviour Of The Queen Conch Strombus Gigas, J Gascoigne, Rn Lipcius

VIMS Articles

Effectiveness of conservation measures for diminished populations depends on the mechanism producing low abundance. In queen conch, which is heavily exploited, reproductive activity is depressed where conch density is low, which may be due to the Allee effect, poor habitat quality, or delayed functional maturity. To determine the mechanism underlying impaired reproduction in shallow seagrass beds, mature conch were translocated from 'source' sites with high and low, ambient conch density (similar to1000 and similar to20 conch ha(-1), respectively), and kept at high density in enclosures within high- and low-density 'host' sites. We monitored reproductive activity, and modelled conch population ...