Kevin D. Friedland , Paula Fratantoni , Adrienne Silver , Damian C. Brady , Avijit Gangopadhyay , Scott I. Large , Ryan E. Morse , David W. Townsend , Marjorie A.M. Friedrichs , D. Christopher Melrose
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引用次数: 0
Abstract
The Northeast US Continental Shelf (NES) is a highly productive marine ecosystem that has experienced wide swings in phytoplankton chlorophyll concentration (CHL). To better understand this variability, we examined changes in CHL over the period 1998–2022, while also considering three indicators of the potential supply of nutrient source waters including cross-shelf advection via deep channels, transport from beyond the shelf edge via Gulf Stream warm core rings (WCR), and input from river and estuarine discharge. Traditionally, deep channel advection of water across the NES was assumed to be derived from Labrador Slope Water (LSW) and Warm Slope Water (WSW). These designations do not fully capture the range of water types contributing to cross-shelf advection. The contribution of LSW and WSW was reciprocal over time, with the presence of WSW at an increased level in recent years. There has been an increase in the number of WCRs off the NES represented by indices of ring occupancy. Precipitation increased over the study period as well, generally over the NES region and in particular in the Mid-Atlantic Bight drainage. We see evidence of the effect of increased precipitation on the NES proper through a change in the area of the ocean surface having 555 nm reflectance with sr−1 > 0.004. Using a canonical analysis, CHL correlated positively with the proportion of LSW and negatively with WSW. These correlations suggest there are aspects of the nutrient content associated with these water masses that are key to phytoplankton growth. WCR frequency negatively correlated with CHL, which was expected since the nutrient loadings of WCRs tends to be low. Finally, CHL negatively correlated with precipitation rate, which suggests terrestrial origin nutrient inputs to the NES are minor. We suggest that in order to understand future CHL dynamics in the NES, careful consideration of advective sources of nutrients in the Northwest Atlantic is necessary.
期刊介绍:
Continental Shelf Research publishes articles dealing with the biological, chemical, geological and physical oceanography of the shallow marine environment, from coastal and estuarine waters out to the shelf break. The continental shelf is a critical environment within the land-ocean continuum, and many processes, functions and problems in the continental shelf are driven by terrestrial inputs transported through the rivers and estuaries to the coastal and continental shelf areas. Manuscripts that deal with these topics must make a clear link to the continental shelf. Examples of research areas include:
Physical sedimentology and geomorphology
Geochemistry of the coastal ocean (inorganic and organic)
Marine environment and anthropogenic effects
Interaction of physical dynamics with natural and manmade shoreline features
Benthic, phytoplankton and zooplankton ecology
Coastal water and sediment quality, and ecosystem health
Benthic-pelagic coupling (physical and biogeochemical)
Interactions between physical dynamics (waves, currents, mixing, etc.) and biogeochemical cycles
Estuarine, coastal and shelf sea modelling and process studies.