An island mixing effect in the coastal gulf of maine

Townsend, David W.; Yentsch, Clarice M.; Parker, Castle E.; Balch, William M.; True, Ernest D.

doi:10.1007/bf01983637

Cited by 13 publications

(7 citation statements)

References 15 publications

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“…The jet flows out of the paper. [52,4 already described for tidal fronts (Pingree et al, 1975;Simpson et al, 1979), topographic fronts (Simpson et al, 1982;Townsend et al, 1983) wind-driven upwellings (Dengler, 1985;Traganza et al, 1987) or plume fronts (Coste et al, 1977). However, in open waters, and in particular for the Mediterranean Sea, well known for its oligotrophic waters, data are more scarce due to the difficulty of applying sampling strategies adapted to the study of such mesoscale structures.…”

Section: I/eandal Distribution Of Pigmentsmentioning

confidence: 94%

Phytoplankton dynamics associated with a geostrophic front: Ecological and biogeochemical implications

Claustre¹,

Kerhervé²,

Marty³

et al. 1994

issn: 0022-2402

144

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Using phytoplankton pigments as biomarkers, we investigated the relationship between the physical forcing and the resulting biological, ecological and biogeochemical properties of the geostrophic front of the Eastern Alboran Sea. (1) Typical frontal sites present biomass levels averaging 60 mg chl a mm2 (up to 100 mg mm2), whereas the adjacent zones (typical Atlantic and Mediterranean) are characterized by an average integrated chlorophyll biomass of 20 mg chl a rnm2. (2) The phytoplankton biomass at front is diatom-dominated and differs markedly from the adjacent zones (typical Atlantic and Mediterranean), flagellate-and cyanobacteriadominated.Therefore, high biomasses at the front do not result from purely physical accumulation but rather from local production.(3) The chlorophyll and diatom biomasses increase from the left to the right side of the Atlantic jet, which supports the hypothesis of a cross-frontal secondary circulation allowing a diatom bloom development. (4) Using assumptions on the carbon/chlorophyll ratio and growth rates for the different phytoplankton taxa, we evaluated the specific productions: diatoms account for 67% of the production at front and only about 10% at adjacent zones. (5) High concentrations of phaeopigments are only found at frontal stations, which points out the pecularities of the food web at the frontal site, compared to adjacent areas. (6) The observations made during this study give a precise picture of that frontal system: autotrophic new production and exportation are enhanced. The implication of this fro&l system on the carbon budget at a regional scale may be important.

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Section: I/eandal Distribution Of Pigmentsmentioning

confidence: 94%

Phytoplankton dynamics associated with a geostrophic front: Ecological and biogeochemical implications

Claustre¹,

Kerhervé²,

Marty³

et al. 1994

issn: 0022-2402

144

View full text Add to dashboard Cite

show abstract

“…At fronts formed by wind-driven upwelling, dense phytoplankton concentrations often develop in and around the uplifted pycnocline (Jones & Halpern 1981, Dengler 1985, Traganza et al 1987. Topographic fronts, formed in the lee of islands and headlands, are often the location of enhanced primary and secondary production (Simpson et al 1982, Townsend et al 1983. Water mass fronts and buoyant plume fronts are also commonly found to exhibit an enhanced biological biomass compared to surrounding waters (Houghton & Marra 1983, Richardson 1985.…”

Section: Introductionmentioning

confidence: 99%

Sink or swim, accumulation of biomass at fronts

Franks¹

1992

Mar. Ecol. Prog. Ser.

426

260

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The dense concentrat~ons of blomass colnmonly seen at fronts are often explalned by a phys~olog~cal response of the oiganlsms to the frontal environment However, some fractlon of the enhanced b~o m a s s may be explalned through purely phys~cal processes the interaction of floating sinking or swlmmlng w~t h the flows at a front To explore this hypothesis, I present a model of steady, 2-dlmenslonal cross-frontal circulat~ons, whlch I combine ~1 1 t h a vanety of swlrnming behaviors The models show how patchmess may arise at fronts through retention and accumulat~on zones, and the patterns which evolve glven vanous flow and swimmlng characterlst~cs The ecological slgnlficance of the results 1s discussed

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“…I). These large tides give rise to swift tidal current velocities and significant turbulent mixing relative to the increase in range (Garrett et al .• 1978; Greenberg, 1979;1983). Bigelow (1927) noted that the major areas of tidal mixing, as indicated by summertime areal distributions of sigma-t differences between 0 and 40 m, were Georges Bank, the southwestern Nova Scotian shelf, the Bay of Fundy and the eastern Maine coast.…”

Section: T Introductionmentioning

confidence: 99%

The importance of a plume of tidally-mixed water to the biological oceanography of the Gulf of Maine

Townsend¹,

Christensen²,

Stevenson³

et al. 1987

J Mar Res

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During the warmer months of the year the eastern Gulf of Maine features a plume of cold water which extends from the tidally well-mixed area adjacent to Grand Manan Island at the mouth of the Bay of Fundy southwest along the Maine coast to well beyond Penobscot Bay. Near Grand Manan Island the plume waters are cold (ca. lOOC), nearly vertically isothermal and carry high concentrations of dissolved inorganic nutrients. The analysis of temperature-salinity diagrams and hydrographic vertical section plots indicate that the deeper waters in Jordan Basin, of slope water origin, upwell and contribute a significant fraction of the high nutrient concentrations. The plume waters become increasingly stratified as they flow to the southwest which leads to a phytoplankton bloom downstream. Nitrate concentrations within the euphotic zone of the plume decrease approximately linearly (ca. 194 mg-at N0 3-N • m-2) along a distance of about 130 km travelled after its exit from the Grand Manan area (ca 7.5 days transit time). Cross frontal mixing and tidal flushing along the south and north sides of the plume could account for ca. 18% of this decrease. Total chlorophyll concentrations increase nearly linearly with distance along the first 80 km and then decrease in the following 50 km, presumably the result of phytoplankton being grazed by zooplankton which apparently propagate in response to the increasing chlorophyll levels. Over the distance of increasing chlorophyll concentrations (80 km) the nitrate decrease, corrected for physical losses laterally, would support a "new". primary production of 1.46 gm C m-2 d-I. Our analyses suggest that as much as 44% of the new nitrate which enters the Gulf of Maine at depth through the Northeast Channel upwells in the eastern Gulf becoming part of the plume, and hence this feature appears to be very important to the nutrient budget and general biological oceanography of the inner Gulf of Maine.

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An island mixing effect in the coastal gulf of maine

Cited by 13 publications

References 15 publications

Phytoplankton dynamics associated with a geostrophic front: Ecological and biogeochemical implications

Phytoplankton dynamics associated with a geostrophic front: Ecological and biogeochemical implications

Sink or swim, accumulation of biomass at fronts

The importance of a plume of tidally-mixed water to the biological oceanography of the Gulf of Maine

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