Biogeochemical impact of summertime coastal upwelling on the New Jersey Shelf

Abstract

The alternative hypothesis that observed regions of recurrent hypoxia on the New Jersey inner shelf are more related to coastal upwelling than riverine inputs of nutrients was investigated through a series of multidisciplinary research programs beginning in 1993. The largest variations in ocean temperatures along the New Jersey coast, other than seasonal, are found to be caused by episodic summertime upwelling events driven by southwesterly winds associated with the atmospheric Bermuda High. Off the southern coast of New Jersey, topographic variations associated with ancient river deltas cause upwelled water to evolve into an alongshore line of recurrent upwelling centers that are colocated with historical regions of low dissolved oxygen. Recurrent upwelling centers are observed every summer in a 9-year data set. The most significant upwelling events occur in summers following colder than usual falls and winters. Size and duration of individual events are correlated and are found to depend on the wind forcing history that effects the inner side of the Middle Atlantic Cold Pool, the precipitation history that effects the strength of the Hudson River plume, and the mixing storm frequency. Upwelling results in a significant enhancement of particulate organic carbon. The typical carbon enhancement associated with the upwelling is sufficient to deplete 75% of the oxygen in the bottom water, making it borderline hypoxic. This indicates that topographically controlled coastal upwelling, rather than riverine inputs, is the more probable mechanism for generating the historical regions of recurrent hypoxia observed along the New Jersey coast.

Short-term upwelling events modulate fish sound production at a mid-Atlantic Ocean observatory

“…Lower temperatures usually coincided with higher dissolved oxygen levels during this study period, a relationship that may be reversed during coastal upwelling in the summer (Glenn et al 2004). During upwelling, southwesterly long-shore winds force warm, low-salinity surface water seaward away from the site via Eckman transport.…”

“…In the case of a migrant such as weakfish Cynoscion regalis, maturation probably begins earlier at overwintering sites near or south of Cape Hatteras, and temperature influences spawning activity locally, either by direct influence of metabolic rate or by attraction to and retention within a suitable spawning area. Interestingly, cusk eels did not reduce their level of calling during the upwelling event, while the level of recorded sounds was reduced for sciaenids.Mar Ecol Prog Ser 375Lower temperatures usually coincided with higher dissolved oxygen levels during this study period, a relationship that may be reversed during coastal upwelling in the summer (Glenn et al 2004). During upwelling, southwesterly long-shore winds force warm, low-salinity surface water seaward away from the site via Eckman transport.…”

Sub-kilometer length scales in coastal waters

“…This condition is conducive to identify horizontal CSVs as a function of depth, however as upwelling progresses the physical environment will tend toward baroclinic conditions (Rao et al, 2005;Hamilton and Rattray, 1978;O'Brien and Hurlburt, 1972), with vertical displacement of isopycnals variable relative to horizontal distance offshore Glenn et al, 2004).…”

Significance of Submarine Groundwater Discharge in Nutrient Budgets in Tropical Sanya Bay, China

“…For example, acidification and hypoxia occur in coastal waters induced by upwelling [1][2][3][4][5] and coastal eutrophication and consequent hypoxia are observed due to increasing terrestrial nutrient loadings from catchment areas [6]. These massive nutrient inputs often stimulate phytoplankton growth in coastal waters and result in the conversion of inorganic carbon to organic carbon [6], which is an important step in the marine carbon cycle.…”