Investigating the larval/juvenile notothenioid fish species assemblage in Mcmurdo Sound, Antarctica using phylogenetic reconstruction

• Main Author: Murphy, Katherine R
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: Antarctica; communities; larval fish; McMurdo; mitochondrial DNA; NADH dehydrogenase subunit 2; ND2; notothenioid; phylogenetic reconstruction; species assemblages; Austral; McMurdo Sound; Ross Sea; Terra Nova Bay; Antarc*
• Online Access: http://hdl.handle.net/2142/78472

Aim: To investigate and identify the species found within the little-known larval and juvenile notothenioid fish assemblage of McMurdo Sound, Antarctica, and to compare this assemblage to the well-studied local adult community. Location: McMurdo Sound, Antarctica. Methods: We extracted genomic DNA from larval and juvenile notothenioid fishes collected from McMurdo Sound during the austral summer and used mitochondrial ND2 gene sequencing with phylogenetic reconstruction to make definitive species identifications. We then surveyed the current literature to determine the adult notothenioid communities of McMurdo Sound, Terra Nova Bay, and the Ross Sea, and subsequently compared them to the species identified in our larval/juvenile specimens. Results: Of our 151 larval and juvenile fishes, 142 specimens or 94.0% represented seven species from family Nototheniidae. Only one specimen was not matched directly to a reference sequence but instead was placed as sister taxon to Pagothenia borchgrevinki with a bootstrap value of 100 and posterior probability of 1.0. The nine non-nototheniid specimens represented the following six species: Pogonophryne scotti, Pagetopsis maculatus, Chionodraco myersi, Chionodraco hamatus, Neopagetopsis ionah, and Psilodraco breviceps. Main conclusions: All of our specimens (100%) were identified as notothenioids, closely matching the adult fauna which is 91% notothenioid. Our specimens were overwhelming nototheniid (94% abundance), compared to the 50% nototheniid abundance that is seen in adults, indicating that our data suffer from sampling bias – a common problem in larval studies. Surprising results included a specimen that we hypothesize to be Pagothenia brachysoma as it was placed as sister taxon to P. borchgrevinki. Additionally, C. hamatus, C. myersi, N. ionah, P. maculatus, and P. scotti have never yet been documented in McMurdo Sound though they are found in the nearby Ross Sea. Finally, P. breviceps is of note as this larval fish was collected approximately 7,000 miles away from any adult specimen of this species. This study also provides the framework for future studies of gene flow and population connectivity both within McMurdo Sound and with the much larger, nearby Ross Sea and presents the first investigation into the larval fish diversity of McMurdo Sound.