Long-term observations of pteropod phenology along the Western Antarctic Peninsula

Distribution and Abundances of Planktic Foraminifera and Shelled Pteropods During the Polar Night in the Sea-Ice Covered Northern Barents Sea

“…This coincides with studies from the Arctic Ocean and Svalbard fjords that suggest a breeding period of L. helicina during autumn (Kobayashi, 1974;Gannefors et al, 2005). Recently, an active grow of Limacina helicina antarctica has been reported throughout the winter season in the Southern Ocean (Thibodeau et al, 2020). Therefore, it is possible that the occurrence of living juveniles in December may indicate that a growth of the overwintering L. helicina (veligers into juveniles) occurred despite of the lack of daylight (hence limited primary production), the increase and thickening of sea-ice cover and declining food quality during early winter months (October to December).…”

“…This may suggest that L. helicina, as the subpolar planktic foraminiferal species T. quinqueloba, adapted to and/or survived the very low temperatures in situ under the sea-ice cover in the northern Barents Sea. The life cycle of planktic foraminifera in high latitudes in winter is still unknown and the overwintering strategy of pteropods is still under debate (Lischka and Riebesell, 2012;Berge et al, 2020;Thibodeau et al, 2020). Independent from, whether pteropods live in a stage of reduced metabolism (Lischka and Riebesell, 2012) or the overwintering strategy is no change in metabolism with a continued active growth (Berge et al, 2020;Thibodeau et al, 2020), they are able to adapt to and survive harsh conditions of the under-ice waters.…”

“…It is still under debate if Arctic pteropods, such as Limacina helicina, slow down their metabolism and growth during wintertime or continue the metabolic activity (Lischka and Riebesell, 2012;Berge et al, 2020;Thibodeau et al, 2020). Furthermore, a recent study from the west Antarctic Peninsula has shown evidence that Limacina helicina antarctica shells actively grow during the ice-covered winter season with continued growth into the summer (Thibodeau et al, 2020). The overwintering strategy is suggested to exert a domineering impact on the ability of pteropods to counteract changes in their environment.…”

Long‐term patterns in ecosystem phenology near Palmer Station, Antarctica, from the perspective of the Adélie penguin

“…Limacina rangii pteropods were also collected from the sediment trap from 2003-2004 to 2017-2018 and typically were present from April to December due to their ontogenetic vertical migration (see methods in Thibodeau, Steinberg, McBride, et al, 2020). Date of appearance was determined as the median date during the first sampling interval when more than 10 unbroken L. rangii shells were present in a sample cup for a given year (Thibodeau, Steinberg, McBride, et al, 2020). Macro-and mesozooplankton were collected twice per week at Station E from December to March during the 2017-2018 and 2018-2019 field seasons.…”

“…While spring preconditioning, specifically the timing of sea ice retreat and its extent, is a dominant physical force governing biological processes at all trophic levels (Saba et al, 2014), it is generally unclear how the winter and spring setup drives summer ecosystem shifts and how these shifts cascade from one trophic level to the next. A few studies have shown phenological shifts in phytoplankton (Schofield et al, 2017), zooplankton (Thibodeau, Steinberg, McBride, et al, 2020), and predators (Cimino et al, 2019), but in some instances, it is unclear whether these shifts are related to the timing of other biophysical processes. Further, past studies have used monthly or seasonal composites of variables to explain species phenological responses, which may not be ecologically relevant or sufficient to capture variability on sub‐monthly scales (Kim et al, 2016).…”