Inter-annual variability of summer mesozooplankton communities of the western Chukchi Sea: 2004–2012

Long-Term Changes in Summer Zooplankton Communities of the Western Chukchi Sea, 1945–2012

“…A growing body of literature for many regions of the Arctic demonstrates the close relationship of zooplankton community structure to water column properties and water mass distribution (summarized in Wassmann et al, in press). This relationship is particularly pronounced within the Chukchi Sea, where several incoming Pacific water masses of different origin carry distinct planktonic communities (e.g., Hopcroft et al, 2010;Eisner et al, 2012;Ershova et al, 2015) that dilute or displace the resident Arctic shelf communities. With the higher frequency of warmer summer temperatures during recent years and a longer ice-free period, it is expected that Pacific species will be transported farther north into the Arctic and will remain in the plankton for longer time periods, potentially competing for resources with resident Arctic species.…”

“…We have intentionally excluded studies that were confined to the shelf break (i.e., the Shelf Basin Interaction [SBI] program [Grebmeier and Harvey, 2006], the Burton Island expedition, and others) to avoid encompassing the distinct Arctic Basin communities (e.g., Kosobokova and Hopcroft, 2010), as well as studies confined to the most northeastern Chukchi (e.g., Questel et al, 2013) with the notable exceptions of the 1976 expedition on R/V Mayak (Pavshtiks, 1984), the 1988 BERPAC (Joint US-USSR Bering-Pacific Expedition; Kulikov, 1992) survey, and four RUSALCA expeditions -2012Ershova et al, 2015 …”

“…Documenting temporal or climatological trends is further complicated by lengthy temporal gaps in the historical data, with several decades lacking any observations. Recent Chukchi Sea work repeatedly shows that planktonic communities exhibit an extremely high level of variability-spatially, seasonally, and interannually (Matsuno et al, 2011;Questel et al, 2013;Ershova et al, 2015). Thus, one of the central challenges when examining a time series, such as the one analyzed in this study, will be discerning natural variability vs. climate-mediated long-term change.…”

DNA barcodes unite two problematic taxa: the meiobenthic Boreohydra simplex is a life-cycle stage of Plotocnide borealis (Hydrozoa: Aplanulata)

“…Recent surveys record the medusa in the plankton during the open water season (August-September), but only in low numbers (Ershova et al 2015). The species has a troubled taxonomic history, having been allied to several different families, and is presently incertae sedis within the hydrozoan suborder Capitata (Schuchert 2015).…”

From sea ice to seals: A moored marine ecosystem observatory in the Arctic

“…An oceanic pressure and elevation differential between the Pacific and the Arctic Oceans is the driving force for this transport (Stigebrandt, 1984), moving water, heat, nutrients, organic carbon, and organisms northward, 35 leading to transformations on the shelf en route to the deep Arctic Ocean. Large late spring and summertime phytoplankton blooms (Sambrotto et al, 1984;Springer et al, 1996; Arrigo et al, 2014; Hill et al, in press) make the Chukchi continental shelf an extremely productive marine ecosystem that supports a thriving benthos (Grebmeier et al, 2006), zooplankton (Ershova et al, 2015), seabirds (Kuletz et al, 2015) and marine mammals . The Chukchi Sea shelf is part of a broader Arctic system undergoing rapid change.…”