Rapid Climate-Driven Circulation Changes Threaten Conservation of Endangered North Atlantic Right Whales

Abstract

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The role of sand lances (Ammodytes sp.) in the Northwest Atlantic Ecosystem: A synthesis of current knowledge with implications for conservation and management

“…The shift in deep water salinity and temperature anomalies in deep‐eastern Gulf of Maine waters corresponds to the recent weakening of Atlantic Meridional Overturning Circulation and northward shift of the Gulf Stream (Caesar, Rahmstorf, Robinson, Feulner, & Saba, 2018). Since 2010, observed abundances of lipid‐rich stages of C. finmarchicus in the Maine Coastal Current and Wilkinson Basin have declined by about 30%, consistent with a lower supply in the eastern Gulf of Maine and partial amplification of the coastal current (Record et al, 2019).…”

“…Calanus species, notably C. finmarchicus (Calanidae) , were historically abundant in the deep waters (>75 m depth) of the Gulf of Maine (Bigelow, 1926; Durbin, Gilman, Campbell, & Durbin, 1995; Runge & Jones, 2012), where densities have been as high or higher than anywhere across the NWA, even though this area represents the southernmost margin of their subarctic range (Melle et al, 2014). C. finmarchicus exhibits high interannual and seasonal variability in the Gulf of Maine (Record et al, 2019). Historically, older stages were transported from the Gulf of St. Lawrence during summer and fall into the eastern Gulf of Maine, with contributions by the subsurface Labrador Subarctic Slope Water (Head, Harris, & Petrie, 1999; MERCINA Working Group et al, 2001; Record et al, 2019) in the Nova Scotia Current (Appendix S1: Supplemental 1) (Kane, 2007; Pershing et al, 2005).…”

“…C. finmarchicus exhibits high interannual and seasonal variability in the Gulf of Maine (Record et al, 2019). Historically, older stages were transported from the Gulf of St. Lawrence during summer and fall into the eastern Gulf of Maine, with contributions by the subsurface Labrador Subarctic Slope Water (Head, Harris, & Petrie, 1999; MERCINA Working Group et al, 2001; Record et al, 2019) in the Nova Scotia Current (Appendix S1: Supplemental 1) (Kane, 2007; Pershing et al, 2005). However, shifts in seasonal oceanographic conditions, circulation and the phenology of lower trophic level species are affecting established patterns in regional timing and availability of resources (see Sections 4.1 and 4.2; Staudinger et al, 2019; Thomas et al, 2017).…”

“…Since 2010, evidence points to a shift in the external source that supplies C. finmarchicus , NWA Ammodytes’ primary prey during the spring season, into the Gulf of Maine as more warm and saline ( Calanus ‐poor) Atlantic slope water and less cold ( Calanus ‐rich) Nova Scotia shelf current enters at depth through the Northeast Channel (Record et al, 2019). The shift in deep water salinity and temperature anomalies in deep‐eastern Gulf of Maine waters corresponds to the recent weakening of Atlantic Meridional Overturning Circulation and northward shift of the Gulf Stream (Caesar, Rahmstorf, Robinson, Feulner, & Saba, 2018).…”

“…One source of variability is the match or mismatch of food available to C. finmarchicus emerging from diapause in spring, which has already advanced in time, and is predicted to continue advancing, due to earlier spring warming (Maps et al, 2011; Pierson, Batchelder, Saumweber, Leising, & Runge, 2013). Shifts in the timing of seasonal events during recent decades are linked to changes in primary productivity and growth cycles leading to large earlier cohorts of C. finmarchicus , despite reduced overwintering stock (Record et al, 2019; Staudinger et al, 2019). Changes in spring production affect the supply of C. finmarchicus in subsequent seasons, particularly on Stellwagen Bank, Georges Bank and elsewhere in coastal waters of Southern New England (Greene & Pershing, 2007).…”