The influence of glacial melt and retreat on the nutritional condition of the bivalve Nuculana inaequisculpta (Protobranchia: Nuculanidae) in the West Antarctic Peninsula

Abstract

Due to climate change, numerous ice bodies have been lost in the West Antarctic Peninsula (WAP). As a consequence, deglaciation is expected to impact the marine environment and its biota at physiological and ecosystem levels. Nuculana inaequisculpta is a marine bivalve widely distributed around Antarctica that plays an important role for ecosystem functioning. Considering that N. inaequisculpta inhabits coastal areas under effect of glacial melt and retreat, impacts on its nutritional condition are expected due to alterations on its physiology and food availability. To test this hypothesis, biochemical composition (lipids, proteins, and fatty acids) and energy content were measured in individuals of N. inaequisculpta collected in a fjord at different distances to the retreating glacier in the WAP. Oceanographic parameters of the top and bottom-water layers (temperature, salinity, dissolved oxygen, and chlorophyll-a) were measured to investigate how the environment changes along the fjord. Results showed that surface oceanographic parameters displayed a lower temperature and dissolved oxygen, but a higher salinity and chlorophyll-a content at nearest compared to farthest sites to the glacier. In contrast, a lower temperature and chlorophyll-a, and a higher salinity and dissolved oxygen was measured in the bottom-water layer toward the glacier. N. inaequisculpta had a higher amount of lipids (17.42 ± 3.24 vs. 12.16 ± 3.46%), protein (24.34 ± 6.12 vs. 21.05 ± 2.46%) and energy content (50.57 ± 6.97 J vs. 39.14 ± 5.80 J) in the farthest compared to the nearest site to the glacier. No differences were found in total fatty acids among all sites. It seems likely that lower individual fitness related to proximity to the glacier would not be related to nutritional quality of sediment food, but rather to food quantity.

Gene flow in the Antarctic bivalveAequiyoldia eightsii(Jay, 1839) suggests a role for the Antarctic Peninsula Coastal Current in larval dispersal

“…The population of Yelcho was supported as a source population and thus, an important source of propagules and genetic diversity for recolonization [15]. Efforts to monitor this area are highly recommended if conservation plans need to be taken, especially in a time of rapid climate change at the WAP [48], where increased temperatures and rapid glaciar retreat may impact ocean circulation-and, consequently, gene flow and metapopulation dynamics-in unpredictable ways. The role of the ACC on species dispersal has been well documented for several taxa, but much less is known in this regard of the importance of other, more localized (and more nearshore) currents.…”

The Clam Before the Storm: A Meta Analysis Showing the Effect of Combined Climate Change Stressors on Bivalves

“….g., De Groot, 1984;Baeta et al, 2014). Akin to other calcifying invertebrate organisms, it has been hypothesised that the physiochemical changes resulting from climate change will reduce bivalve growth, impair maintenance of shells (Maynou et al, 2020;Knights et al, 2020), and disrupt larval settlement patterns and spawning (Bascur et al, 2020;Figueirodo et al, 2022). In recognition of the environmental, social, and economic benefits bivalves produce, and the current and future pressures they face, the group is a focus for conservation efforts (zu Ermgassen et al, 2020;Buelow andWaltham, 2020, Gagnon et al, 2020).…”