Diversity, relative abundance, new locality records and population structure of Antarctic demersal fishes from the northern Scotia Arc islands and Bouvetøya

Abstract

International audienceA primary objective of the ICEFISH 2004 cruise was to collect and study notothenioid fishes from remote localities in the Atlantic sector of the Southern Ocean. Nearly 1 month was devoted to bottom trawling for fishes on the shelf and upper slope (to 1,000 m) areas around Shag Rocks, South Georgia, South Sandwich Islands and Bouvetøya. The focus was on the latter two locations, because their faunas are more poorly known. Eight species were collected at Shag Rocks with Patagonotothen guntheri most abundant; 17 at South Georgia with Lepidonotothen nudifrons, L. larseni and Gobionotothen gibberifrons most abundant; 13 at the South Sandwich Islands with L. larseni, L. nudifrons and G. gibberifrons most abundant; and 11 at Bouvetøya with L. larseni, Macrourus holotrachys and L. squamifrons most abundant. Ten new locality records were established: Shag Rocks (1), South Georgia (1), South Sandwich Islands (5), South Sandwich Trench at 5,350 m (1) and Bouvetøya (2). Total known demersal fish diversity on the shelf and upper slope at Shag Rocks/South Georgia, South Sandwich Islands and Bouvetøya is 42, 31 and 17 species, respectively. To examine population structure in the four most abundant notothenioids at Bouvetøya (L. larseni, L. squamifrons, Notothenia coriiceps and Chaenocephalus aceratus), we examined the ND2 portion of mitochondrial DNA. Chaenocephalus aceratus, N. coriiceps and L. larseni exhibited no significant genetic differentiation in comparison with samples from localities in the Scotia Sea and the Antarctic Peninsula. However, L. squamifrons showed significant genetic differentiation between the South Shetlands and Bouvetøya populations (F ST = 0.189, P = 0.015). Thus, these data combined with previous studies of two other notothenioids suggest that five of the six notothenioid species at Bouvetøya are not genetically differentiated from other localities in the Atlantic sector of the Southern Ocean. The location of Bouvetøya within the Antarctic Circumpolar Current and the long (1–2 years) pelagic stages of the notothenioids at Bouvetøya may be at least partly responsible for this genetic homogeneit

Population genetic structure and gene flow patterns between populations of the Antarctic icefish Chionodraco rastrospinosus

“…Support for this proposition comes indirectly from the recent study of Ashford et al. (2010), who suggested an extensive larval phase of Chaenocephalus aceratus lasting between 400 and 500 days, consistent with a survey in Bouvet Island in which all detected nototheniid and channichthyid species had long larval durations of 1–2 years (Jones et al. , 2008).…”

“…, 2006). Additionally, at a small scale, Jones et al. (2008) detected no significant divergence between samples from the Scotia Sea and Antarctic Peninsula (South Shetland Islands, South Georgia and South Sandwich Islands) and Bouvet Island (2500 km east of South Georgia) for three different demersal notothenioid species using mtDNA data.…”

Is the Species Flock Concept Operational? The Antarctic Shelf Case

“…Therefore the Trematominae can be considered as a smaller and more recent flock restricted to the Antarctic shelf and a few peri-insular shelves (e.g. South Georgia and South Sandwich islands [46].…”

First evidence of widespread active methane seepage in the Southern Ocean, off the sub-Antarctic island of South Georgia

“…The epibenthic invertebrate megafauna observed in the Cumberland Bay area comprises species commonly found around South Georgia [36][37][38] . Except for the inferred microbial mats chemosynthetic organisms usually found at cold seep sites were not found at the seeps investigated in this study.…”