Tidal pumping and nutrient fluxes on Georges Bank: A process-oriented modeling study

Hu, Song; Townsend, David W.; Chen, Changsheng; Cowles, Geoffrey W.; Beardsley, Robert C.; Ji, Rubao; Houghton, Robert W.

doi:10.1016/j.jmarsys.2008.04.007

Cited by 36 publications

(33 citation statements)

References 41 publications

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“…4), and also a larger volatility in chl-a in spite of similar volatilities in temperature and nutrients. A high volatility in biomass is predicted to signal dynamic chaos (Scheffer et al 2001) and support the finding that interaction patterns at shallow waters are qualitatively different from those at deep waters e.g., as in Malin et al (2005) and Hu et al(2008).…”

Section: Differences Between Regions In Coastal Waterssupporting

confidence: 73%

Investigating possible causal relations among physical, chemical and biological variables across regions in the Gulf of Maine

Seip

2014

Hydrobiologia

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We examine potential causal relations between ecosystem variables in four regions of the Gulf of Maine under two major assumptions: i) a causal cyclic variable will precede, or lead, its effect variable; e.g., a peak (through) in the causal variable will come before a peak (through) in the effect variable. ii) If physical variables determine regional ecosystem properties, then independent clusters of observations of physical, biological and interaction variables from the same stations will show similar patterns. We use the Leadinglagging, LL-strength method to establish leading strength and potential causality, and we use Principal component analysis, PCA, to establish if regions differ in their ecological characteristics. We found that several relationships for physical and chemical variables were significant, and consistent with "common knowledge" of causal relations. In contrast, relationships that included biological variables differed among regions. In spite of these findings, we found that physical and chemical characteristics of near shore and pelagic regions of the Gulf of Maine translates into unique biological assemblages and unique physicalbiological-interactions.

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Section: Differences Between Regions In Coastal Waterssupporting

confidence: 73%

Investigating possible causal relations among physical, chemical and biological variables across regions in the Gulf of Maine

Seip

2014

Hydrobiologia

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“…Tidal pumping is thought to be the primary mechanism by which cold, salty, nutrient-rich water is brought up onto the bank, primarily along the northern edge (Franks and Chen, 2001; Horne et al, 1989; Hu et al, 2008; Ji et al, 2008). The bulk of the new nitrate is presumably taken up by phytoplankton other than A. fundyense , given that it makes up such a small component of the autotrophic biomass.…”

Section: Discussionmentioning

confidence: 99%

“…Tidal pumping provides a persistent source of nutrients from the adjacent deep basins (Franks and Chen, 2001; Horne et al, 1989; Hu et al, 2008; Ji et al, 2008). Phytoplankton chlorophyll is typically highest on the crest and decreases in the deeper areas along the periphery of the bank, with high rates of primary production throughout the year (O’Reilly et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

Georges Bank: A leaky incubator of Alexandrium fundyense blooms

McGillicuddy

Townsend

Keafer

et al. 2014

Deep Sea Research Part II: Topical Studies in Oceanography

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A series of oceanographic surveys on Georges Bank document variability of populations of the toxic dinoflagellate Alexandrium fundyense on time scales ranging from synoptic to seasonal to interannual. Blooms of A. fundyense on Georges Bank can reach concentrations on the order of 104 cells l−1, and are generally bank-wide in extent. Georges Bank populations of A. fundyense appear to be quasi-independent of those in the adjacent coastal Gulf of Maine, insofar as they occupy a hydrographic niche that is colder and saltier than their coastal counterparts. In contrast to coastal populations that rely on abundant resting cysts for bloom initiation, very few cysts are present in the sediments on Georges Bank. Bloom dynamics must therefore be largely controlled by the balance between growth and mortality processes, which are at present largely unknown for this population. Based on correlations between cell abundance and nutrient distributions, ammonium appears to be an important source of nitrogen for A. fundyense blooms on Georges Bank.

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“…Based on the above observations and the BNL-cyst distribution data presented here, it is suggested that the southerly extension of the MCC may periodically be associated with a high abundance of suspended cysts in the underlying BNLs. If the cysts are eventually carried farther south to the northern side of Georges Bank, strong tidal mixing and upwelling (Franks and Chen, 1996; Chen and Beardsley, 1998; Townsend and Thomas, 2001; Hu et al, 2008) could bring those cysts to the surface where favorable nutrient and light conditions would allow them to bloom. Obviously, this pathway of suspended cyst transport from the central gulf to Georges Bank is not resolved by the present data and a comprehensive assessment of that potential awaits further study.…”

Section: Discussionmentioning

confidence: 99%

Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

Pilskaln

Hayashi

Keafer

et al. 2014

Deep Sea Research Part II: Topical Studies in Oceanography

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Cysts residing in benthic nepheloid layers (BNLs) documented in the Gulf of Maine have been proposed as a possible source of inoculum for annual blooms of a toxic dinoflagellate in the region. Herein we present a spatially extensive data set of the distribution and thickness of benthic nepheloid layers in the Gulf of Maine and the abundance and inventories of suspended Alexandrium fundyense cysts within these near-bottom layers. BNLs are pervasive throughout the gulf and adjacent Bay of Fundy with maximum layer thicknesses of 50–60 m observed. Mean BNL thickness is 30 m in the eastern gulf and Bay of Fundy, and 20 m in the western gulf. Cyst densities in the near-bottom particle resuspension layers varied by three orders of magnitude across the gulf with maxima of 105 cysts m−3. An important interconnection of elevated BNL cyst densities is observed between the Bay of Fundy, the Maine Coastal Current and the south-central region of the gulf. BNL cyst inventories estimated for the eastern and western gulf are each on the order of 1015 cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 1016 . Although BNL cyst inventories in the eastern and western gulf are 1–2 orders of magnitude smaller than the abundance of cysts in the upper 1 cm of sediment in those regions, BNL and sediment-bound cyst inventories are comparable in the Bay of Fundy. The existence of widespread BNLs containing substantial cyst inventories indicates that these near-bottom layers represent an important source of germinating A. fundyense cysts in the region.

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Tidal pumping and nutrient fluxes on Georges Bank: A process-oriented modeling study

Cited by 36 publications

References 41 publications

Investigating possible causal relations among physical, chemical and biological variables across regions in the Gulf of Maine

Investigating possible causal relations among physical, chemical and biological variables across regions in the Gulf of Maine

Georges Bank: A leaky incubator of Alexandrium fundyense blooms

Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

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