Tracking : population dynamics and ecology of and in an Alabama estuary.

Unlabelled: is a genus of halophilic, gram-negative bacteria found in estuaries around the globe. Integral parts of coastal cultures often involve contact with vectors of pathogenic spp. (e.

Organic polymer consumption facilitates domoic acid entry into the marine food web without direct ingestion of Pseudo-nitzschia.

Domoic acid (DA) is a neurotoxin produced by diatoms from the genera Pseudo-nitzschia and Nitzschia. DA is transferred through the food web when consumed by organisms such as copepods (e.g.

Silicic acid limitation drives bloom termination and potential carbon sequestration in an Arctic bloom.

The spring diatom bloom in the Arctic Ocean accounts for significant annual primary production leading to the most rapid annual drawdown of water-column pCO. Late-winter waters in the Atlantic Arctic & Subarctic Provinces (AASP) have lower silicic acid concentrations than nitrate, which suggests diatom blooms may deplete Si before N. Here we test a facet of the hypothesis that silicic acid limitation terminates the spring diatom bloom in the AASP and the sinking of the senescent and dead diatoms helps drive carbon sequestration.

Diatom populations in an upwelling environment decrease silica content to avoid growth limitation.

A mix of adaptive strategies enable diatoms to sustain rapid growth in dynamic ocean regions, making diatoms one of the most productive primary producers in the world. We illustrate one such strategy off coastal California that facilitates continued, high, cell division rates despite silicic acid stress. Using a fluorescent dye to measure single-cell diatom silica production rates, silicification (silica per unit area) and growth rates we show diatoms decrease silicification and maintain growth rate when silicon concentration limits silica production rates.

Taxon-specific contributions to silica production in natural diatom assemblages.

The metabolic activity and growth of phytoplankton taxa drives their ecological function and contribution to biogeochemical processes. We present the first quantitative, taxon-resolved silica production rates, growth rates, and silica content estimates for co-occurring diatoms along two cross-shelf transects off the California coast using the fluorescent tracer PDMPO (2-(4-pyridyl)-5-((4-(2-dimethylaminoethylaminocarbamoyl)methoxy)phenyl)oxazole), and confocal microscopy. Taxon contribution to total diatom community silica production was predominantly a function of the surface area of new frustule that each taxon created as opposed to cell abundance or frustule thickness.

Patterns and regulation of silicon accumulation in Synechococcus spp.

Six clones of the marine cyanobacterium Synechococcus, representing four major clades, were all found to contain significant amounts of silicon in culture. Growth rate was unaffected by silicic acid, Si(OH) , concentration between 1 and 120 μM suggesting that Synechococcus lacks an obligate need for silicon (Si). Strains contained two major pools of Si: an aqueous soluble and an aqueous insoluble pool.

Mesozooplankton biomass and grazing in the Costa Rica Dome: amplifying variability through the plankton food web.

We investigated standing stocks and grazing rates of mesozooplankton assemblages in the Costa Rica Dome (CRD), an open-ocean upwelling ecosystem in the eastern tropical Pacific. While phytoplankton biomass in the CRD is dominated by picophytoplankton (<2-µm cells) with especially high concentrations of spp, we found high mesozooplankton biomass (∼5 g dry weight m) and grazing impact (12-50% integrated water column chlorophyll ), indicative of efficient food web transfer from primary producers to higher levels. In contrast to the relative uniformity in water-column chlorophyll and mesozooplankton biomass, variability in herbivory was substantial, with lower rates in the central dome region and higher rates in areas offset from the dome center.

Net biogenic silica production and the contribution of diatoms to new production and organic matter export in the Costa Rica Dome ecosystem.

We determined the net rate of biogenic silica (bSiO) production and estimated the diatom contribution to new production and organic matter export in the Costa Rica Dome during summer 2010. The shallow thermocline significantly reduces bSiO dissolution rates below the mixed layer, leading to significant enhancement of bSiO relative to organic matter (silicate-pump condition). This may explain why deep export of bSiO in this region is elevated by an order of magnitude relative to comparable systems.

Quantifying diatom silicification with the fluorescent dye, PDMPO.

Diatoms require silicic acid to construct ornately detailed cell walls called frustules. The growth and geographic distribution of diatoms is often controlled by the availability of silicic acid. Analytical methods exist to assess diatom community biogenic silica (bSiO) production, but partitioning production among taxa has been largely qualitative.

Summer diatom blooms in the North Pacific subtropical gyre: 2008-2009.

The summertime North Pacific subtropical gyre has widespread phytoplankton blooms between Hawaii and the subtropical front (∼30°N) that appear as chlorophyll (chl) increases in satellite ocean color data. Nitrogen-fixing diatom symbioses (diatom-diazotroph associations: DDAs) often increase 10(2)-10(3) fold in these blooms and contribute to elevated export flux. In 2008 and 2009, two cruises targeted satellite chlorophyll blooms to examine DDA species abundance, chlorophyll concentration, biogenic silica concentration, and hydrography.