Decadal changes in zooplankton of the Northeast U.S. continental shelf.
The abundance of the subarctic copepod, Calanus finmarchicus, and temperate, shelf copepod, Centropages typicus, was estimated from samples collected bi-monthly over the Northeast U.S. continental shelf (NEUS) from 1977-2010. Latitudinal variation in long term trends and seasonal patterns for the two copepod species were examined for four sub-regions: the Gulf of Maine (GOM), Georges Bank (GB), Southern New England (SNE), and Mid-Atlantic Bight (MAB). Results suggested that there was significant difference in long term variation between northern region (GOM and GB), and the MAB for both species. C. finmarchicus generally peaked in May - June throughout the entire study region and Cen. typicus had a more complex seasonal pattern. Time series analysis revealed that the peak time for Cen. typicus switched from November - December to January - March after 1985 in the MAB. The long term abundance of C. finmarchicus showed more fluctuation in the MAB than the GOM and GB, whereas the long term abundance of Cen. typicus was more variable in the GB than other sub-regions. Alongshore transport was significantly correlated with the abundance of C. finmarchicus, i.e., more water from north, higher abundance for C. finmarchicus. The abundance of Cen. typicus showed positive relationship with the Gulf Stream north wall index (GSNWI) in the GOM and GB, but the GSNWI only explained 12-15% of variation in Cen. typicus abundance. In general, the alongshore current was negatively correlated with the GSNWI, suggesting that Cen. typicus is more abundant when advection from the north is less. However, the relationship between Cen. typicus and alongshore transport was not significant. The present study highlights the importance of spatial scales in the study of marine populations: observed long term changes in the northern region were different from the south for both species.
Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America.
Hongsheng
H
Bi
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America.
Rubao
R
Ji
Department of Marine Biology, Texas A & M University, Galveston, Texas, United States of America.
Hui
H
Liu
Department of Oceanography, Pusan National University, Busan, South Korea.
Young-Heon
YH
Jo
Northeast Fisheries Science Center Narragansett Laboratory, National Marine Fisheries Service, Narragansett, Rhode Island, United States of America.
Jonathan A
JA
Hare
D000818:Animals; D001267:Atlantic Ocean; D033342:Copepoda / Q000502:physiology*; D017753:Ecosystem; D014481:United States; D015048:Zooplankton / Q000502:physiology*