Feeding Ecology of Odontaster validus under Different Environmental Conditions in the West Antarctic Peninsula

Abstract

To study how Odontaster validus can influence the spatial structure of Antarctic benthic communities and how they respond to disturbance, it is necessary to assess potential dietary shifts in different habitats. We investigated the diets of O. validus from Maxwell Bay and South Bay in the West Antarctic Peninsula. A multifaceted approach was applied including in situ observations of cardiac stomach everted contents, isotopic niche, and trophic diversity metrics. Results confirm the flexible foraging strategy of this species under markedly different environmental conditions, suggesting plasticity in resource use. The data also showed evidence of isotopic niche expansion, high δ15N values, and Nacella concinna as a common food item for individuals inhabiting a site with low seasonal sea ice (Ardley Cove), which could have significant ecological implications such as new trophic linkages within the Antarctic benthic community. These results highlight the importance of considering trophic changes of key species to their environment as multiple ecological factors can vary as a function of climatic conditions.

Shallow Hard-Bottom Benthic Assemblages of South Bay (Antarctic Peninsula): An Update 40 Years Later

“…Odontaster validus was the most abundant species, with a mean density similar to that found on Anvers Island [59] and higher than that reported for McMurdo Sound [73]. Their conspicuous presence in all sites could be due to their ability to vary resource utilization across differing habitat compositions, which may be a key response allowing their persistence and survival in the face of environmental change [74]. The limpet N. concinna showed a significant density in the first meters of all the sites (except for S3); in S4, it was responsible for the high total fauna abundance values, registering at 5 m a density of limpets up to four times greater than in the other sites.…”

Rhodobacteraceae dominate the core microbiome of the sea star Odontaster validus (Koehler, 1906) in two opposite geographical sectors of the Antarctic Ocean

“…The sea star Odontaster validus Koehler, 1906 is a keystone species of Antarctic benthic communities ( Dearborn, 1977 ; Zenteno-Devaud et al, 2022 ), which lives at depths down to ca. 900 m, and has different functional roles in food webs due to its plasticity in feeding behavior (i.e., omnivore, filter feeder, scavenger, herbivore, predator active, scavenger, spongivore; Pearse, 1969 ; McClintock, 1994 ; McClintock et al, 2008 ; Baum and Worm, 2009 ; van den Hoff et al, 2014 ; Zenteno-Devaud et al, 2022 ).…”

“…The sea star Odontaster validus Koehler, 1906 is a keystone species of Antarctic benthic communities ( Dearborn, 1977 ; Zenteno-Devaud et al, 2022 ), which lives at depths down to ca. 900 m, and has different functional roles in food webs due to its plasticity in feeding behavior (i.e., omnivore, filter feeder, scavenger, herbivore, predator active, scavenger, spongivore; Pearse, 1969 ; McClintock, 1994 ; McClintock et al, 2008 ; Baum and Worm, 2009 ; van den Hoff et al, 2014 ; Zenteno-Devaud et al, 2022 ). Investigations on the evolutionary history of O. validus highlighted that the distribution of this species is confined to benthic ecosystems surrounding the Antarctic continent and islands and demonstrated a long-distance genetic similarity due to the vast dispersal potential of the pelagic larval phase lasts for 6 months or more ( Janosik et al, 2011 ).…”

“…In the present study, we investigated the whole-body bacterial microbiome of the sea star O. validus inhabiting the Antarctic Peninsula and several sites of the Ross Sea, the two main marine areas located in opposite geographic sectors of the Southern Ocean. These two distinct Antarctic seas, despite being connected by the Antarctic Circumpolar Current (which has been described as a promoter of genetic connection across the sub-Antarctic zone; Moon et al, 2017 ; Zenteno-Devaud et al, 2022 ), are influenced by different oceanographic processes including the presence of large and deep-reaching cyclonic gyres ( Orsi et al, 1993 ; Jacobs et al, 2002 ; Carter et al, 2008 ; Chown et al, 2015 ) and trophic conditions ( Smith et al, 2012 ), leading to hypothesize a different influence on the sea star microbiome. To test this hypothesis, we assessed the diversity, putative functions, and potential origin (from the surrounding habitats) of the bacterial microbiome of O. validus from the two different Antarctic sectors.…”