The influence of warm‐core rings on slope water entering the Gulf of Maine

Brooks, David A.

doi:10.1029/jc092ic08p08183

Cited by 36 publications

(45 citation statements)

References 22 publications

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“…Data from stations identified by the filled circles are shown in Figure 9; the station names are from a 1982 survey, partly a result of the intense tidal stirring, which continually brings deep nutrients into the euphotic zone, In summer satellite images, the tidally mixed water from the eastern gulf is evident in a plume of cold surface water extending southwestward along the coast from Grand Manan Island to the vicinity of Mt. Desert Island (Fig, I), The cold water traces a nontidal coastal current that is associated with the contrast between buoyant nearshore water and deeper, more saline water confined in Jordan Basin (Brooks, 1985). A fraction of the coastal current turns offshore east of Penobscot Bay and enters a cyclonic gyre that develops in Jordan Basin in the summer.…”

Section: Introductionmentioning

confidence: 95%

Variability of the coastal current and nutrient pathways in the eastern Gulf of Maine

Brooks¹,

Townsend²

1989

J Mar Res

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The eastern Maine coastal current flows southwestward, carrying cold and nutrient-rich waters along the coast from the tidally stirred eastern gulf toward the central and western gulf, where in summer the~aters are warmer and more stratified. The current typically turns offshore before reaching Penobscot Bay, near the central coast, at a location determined largely by the distribution of dense slope water in Jordan Basin. The slope water, which enters the gulf as a deep inflow from the Atlantic Ocean, thus plays a major role in determining the intensity, direction and timing of the delivery of nutrients to the interior gulf. In this paper, we use data from two cruises in August 1987 to examine the variability and nutrient transport of the coastal current, especially to show the important physical linkages between the deep slope water, the structure of the coastal current, and its likely significant effect on biological productivity in the gulf.

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Section: Introductionmentioning

confidence: 95%

Variability of the coastal current and nutrient pathways in the eastern Gulf of Maine

Brooks¹,

Townsend²

1989

J Mar Res

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“…Brooks & Townsend (1989) have observed that the coastal current along the coastal Gulf of Maine, which is presumed to transport larvae away from the eastern Maine spawning ground ), is extremely variable, being subject to redirection as a function of the amount of dense slope water residing immediately offshore in Jordan Basin. The amount of that slope water which enters the Gulf of Maine is in turn likely influenced by the presence of warm core Gulf Stream rings at the mouth of the Northeast Channel (Townsend & Spinrad 1986, Brooks 1987, and hence is an unpredictable and variable phenomen. It is not inconceivable that episodes of greater offshore transport of larvae, at least from the eastern Gulf of Maine, result in better survival through the winter.…”

Section: Recruitment Implicationsmentioning

confidence: 99%

Recruitment implications of larval herring overwintering distributions in the Gulf of Maine, inferred using a new otolith technique

Townsend¹,

Radtke²,

Morrison³

et al. 1989

Mar. Ecol. Prog. Ser.

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We have applied a Sr/Ca ratio technique of otolith analysis to reconstruct the temperature histories of fall-spawned herring larvae Clupea harengus L. captured in inshore waters of the Gulf of Maine, USA, in order to infer their overwintering distributions. Winter survival of herring larvae is believed to be a determinant of recruitment in the Gulf of Maine, though very little is known about this important phase in their life history. Shortly after hatching in coastal spawning areas, larvae congregate inshore along the Maine coast during fall (September to November). Following this abundance peak, inshore larval densities drop to very low levels in mid-winter (late December and January), before a second group of fall-spawned larvae appears inshore in spring (February through April), thus giving a bimodal abundance distribution with time. We have inferred the overwinteriug distributions of larvae captured in the spring in the Sheepscot hver estuary, Maine, by analyzing changes in the concentrations ratios of strontium to calcium in the otoliths. These ratios vary as a function of temperature and thus act as a biological recorder of water temperatures experienced by an individual larva throughout its life history. Results suggest that the spring peak of herring larvae inshore represents larvae which overwintered offshore in the Gulf of Maine, implying that larvae w h c h enter the inshore nursery areas in the fall do not survive.

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“…Nutrients within this basin are upwelled and entrained in the strong south-west flow of the Eastern Maine coastal current (Townsend et al, 1987;Brooks and Townsend, 1989). Part of this current may recirculate in one or more large counter-clockwise gyres centered over Jordan and Wilkinson Basins (Bigelow, 1927;Brooks, 1985Brooks, , 1987Butman and Beardsley, 1987). Some of the central waters may exit the Gulf either via a narrow subsurface jet hugging the north side of Georges Bank or by recirculating around Georges Bank and returning to the New England Shelf south of Cape Cod.…”

Section: Introductionmentioning

confidence: 99%

Water column nutrients and sedimentary denitrification in the Gulf of Maine

Christensen¹,

Townsend²,

Montoya³

1996

Continental Shelf Research

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Abstract--Sedimentary denitrification acts to remove nitrogen from both the sediments and water column in continental shelf ecosystems, so that in enclosed shelf areas where water residence times are long (about a year in the Gulf of Maine), significant rates of sedimentary denitrification might lower inorganic nitrogen concentrations. We examined this using a basin-wide suite of hydrographic and nutrient data collected in mid-summer. Total inorganic nitrogen (TIN) concentrations (nitrate + nitrite + ammonium) were highest in the aged North Atlantic continental slope waters found at depth in the Jordan Basin on the eastern side of the Gulf. Phosphate and silicate concentrations were moderately high in these waters. On the western side of the Gulf, Wilkinson Basin receives much less of the nutrient-rich slope waters. In these deep waters, TIN concentrations were lower and phosphate and silicate concentrations higher than in the Jordan Basin. In the intermediate and deep waters, TIN/PO 4 ratios averaged 19 on the eastern side but only 15-16 on the western side of the Gulf. Partially isolated regions within the Gulf had even lower TIN/PO 4 ratios. The differences in this ratio suggested the occurrence of either a non-stoichiometric reduction in nitrogen or an enrichment in phosphate between the eastern and western sides of the Gulf. The relationship between phosphate and silicate was identical in open waters on both sides of the Gulf, indicating that the difference in the TIN/PO 4 ratio was due to a loss of nitrogen. A parameter, delta-N, quantified the non-stoichiometric nitrogen loss and was defined as, AN = a[PO4] - [TIN], where [PO4] and [TIN] were the measured concentrations in an individual water sample and a was the average TIN/PO4 ratio in the Jordan Basin. Within and below the Maine Intermediate Waters (50--120 m), the distribution of AN showed the removal of 2-4 ~gat N 1 i in most of the waters west and south-west of the Jordan Basin. AN was greater in waters close to the sediments suggesting that sediments were the site of nitrogen removal. The overall rate of denitrification was estimated to be 31.2-46.8 x 109 gat N y l based on the average AN, the water volume within the Gulf and the water residence time. When normalized to sediment area, this rate was 0.80-1.21 pgat N cm 2 s-1. The classical inorganic nitrogen budget of the Gulf of Maine, based on inflow rates and nutrient concentrations of the source waters, was reassessed and found to be unbalanced by 43.1 x 109 gat N y 1 with TIN inputs (138.6 x 109 gat N y 1) exceeding advective TIN losses (-95.5 × 109 gat N y-X). Organic matter burial and net organic nitrogen export at the rate of 1.5 % of the primary productivity could account for 23 % of the imbalance (-10.0 × 109 gat N y-l). Denitrification, at the aerial rate of 0.85 pgat N cm -2 s i accounted for the remainder (-33.1 x 109gat N y-l).

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The influence of warm‐core rings on slope water entering the Gulf of Maine

Cited by 36 publications

References 22 publications

Variability of the coastal current and nutrient pathways in the eastern Gulf of Maine

Variability of the coastal current and nutrient pathways in the eastern Gulf of Maine

Recruitment implications of larval herring overwintering distributions in the Gulf of Maine, inferred using a new otolith technique

Water column nutrients and sedimentary denitrification in the Gulf of Maine

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