Changing Physical Conditions and Lower and Upper Trophic Level Responses on the US Northeast Shelf

Abstract

Sea surface temperature (SST), salinity, and chlorophyll concentration (CHL) have changed in the US Northeast Shelf ecosystem over recent decades. The changes in these parameters were distinctly marked by change points around the year 2012 resulting in a 0.83 • C increase in SST, a 0.3 PSU increase in salinity, and decrease in CHL in excess of 0.4 mg m −3. Where temperature and salinity shifted in mean level around their respective change points, CHL declined in a more monotonic fashion. Modeled data suggest that the shift in CHL resulted in a greater contribution of picoand nanophytoplankton and a decreased contribution of microphytoplankton to overall CHL. Complementary estimates of the contribution of different phytoplankton functional types suggest a diminished contribution of diatoms to the phytoplankton community. Hence, not only is there evidence of a decline in the overall primary production capacity of the ecosystem, but also evidence of a fundamental change in the size and quality of phytoplankton supporting food webs. Two ecosystem responses to the observed changes in SST, salinity, and CHL were analyzed. Both length and weight at age have declined for a number of species, and both measures of growth appear to be negatively associated with temperature and positively associated with CHL. Biomass of fish and macroinvertebrates has declined in recent years, with a decrease in pelagic species associated with a decrease in CHL, while the decline in demersal species was associated with an increase in temperature. Collectively, these ecosystem changes appear to be the result of the complex interactions of both thermal effects and changes at the base of the food web.

COI Metabarcoding of Zooplankton Species Diversity for Time-Series Monitoring of the NW Atlantic Continental Shelf

“…Morphological microscopic examination of zooplankton samples from NEFSC surveys has allowed analysis and interpretation of temporal and spatial patterns of variability across the region (Kane, 2007;Kane, 2011;O'Brien et al, 2013). The time-series records have provided clear evidence that the region is experiencing rapid climate change (O'Brien et al, 2013;Friedland et al, 2020). Regime shifts (i.e., persistent changes in the structure and function of ecosystems) have been documented during the 1990s and 2000s in pelagic community structure (Pershing et al, 2005;Walsh et al, 2015;Morse et al, 2017), including zooplankton diversity (Head and Sameoto, 2007;Record et al, 2010;Johnson et al, 2011;Bi et al, 2014).…”

“…Patterns of species diversity of the many taxonomic groups of marine zooplankton are key characteristics of ocean ecosystems, determining their function, sustainability, and responses to environmental variation and anthropogenic impacts, including climate change (Sherman et al, 2002;Friedland et al, 2020). Pelagic ecosystems of the NW Atlantic Ocean have been monitored and studied over many decades, providing an invaluable time-series record of zooplankton diversity and abundance (Wiebe et al, 2012;O'Brien et al, 2013).…”

The impact of oyster aquaculture on the estuarine carbonate system

“…We also increased the atmospheric pCO 2 to 550 ppm in accordance with estimates from RCP 8.5 (IPCC, 2014). The temperature of the Gulf of Maine has been increasing rapidly this century (Friedland et al, 2020a;Friedland et al, 2020b;Gonçalves Neto et al, 2021) and is expected to continue warming. Brickman et al (2021) also used the same downscaled global models as Siedlecki et al (2021) to estimate that the Gulf of Maine will warm by an additional 0.5 C by 2050 compared to average 2018 temperatures using the RCP 8.5 emissions scenario.…”

Northern shrimp Pandalus borealis population collapse linked to climate-driven shifts in predator distribution

“…Changes in trophic ecology in the GOM have been observed in recent years (e.g. [6,[91][92][93]); however, these seem unlikely to have resulted in a catastrophic decline of post-juvenile northern shrimp given the generalist feeding strategy of the shrimp [23].…”

“…Climate change has led to well-documented changes in marine, terrestrial and freshwater ecological communities stemming from a diversity of processes, including productivity changes, shifts in species distributions, and changes in timing of seasonal events (phenology) [1][2][3][4][5][6][7][8]. These in turn have the potential to alter competitive and predator-prey interactions, with consequences for species dominance, biodiversity and population persistence.…”