Assemblages of micronektonic fishes and invertebrates in a gradient of regional warming along the Western Antarctic Peninsula

• Published in: Journal of Marine Systems
• Main Authors: Parker, Melanie L., Fraser, William R., Ashford, Julian, Torres, Joseph J., PATARNELLO, TOMASO, ZANE, LORENZO
• Other Authors: Patarnello, Tomaso, Zane, Lorenzo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2015
• Subjects: Assemblage; Continental shelf; Macrozooplankton; Micronekton; Pleuragramma; Western antarctic peninsula; Aquatic Science; Oceanography; Ecology; Evolution; Behavior and Systematics; Antarctic; Antarctic Peninsula; Austral; Marguerite; Marguerite Bay; Charcot; Anvers; Renaud; Anvers Island; Joinville; Joinville Island; Croker; Charcot Island; Croker Passage; Renaud Island; Antarc*; Antarctica; Euphausia superba; Thysanoessa macrura
• Online Access: http://hdl.handle.net/11577/3168642; https://doi.org/10.1016/j.jmarsys.2015.07.005

Micronektonic fishes and invertebrates were sampled with 32 midwater trawls at nine sites along the Western Antarctic Peninsula (WAP) in the austral fall (March-April) of 2010. Study sites were located within four hypothesized hydrographic regions: near Joinville Island in Region I, at Croker Passage, near Anvers Island, and near Renaud Island in Region II, within Marguerite Bay and the Marguerite Trough in Region III, and near Charcot Island in Region IV. A total of 62 taxa representing 12 taxonomic groups of pelagic invertebrates and 9 families of fish were captured, but assemblages were dominated by only a few species. The most numerically abundant taxa were the euphausiids, Thysanoessa macrura, Euphausia superba, and E. crystallorophias, combining to contribute nearly 79% of the total catch. Biomass dominants included E. superba, which contributed more than 44% of the total catch, the notothenioid Pleuragramma antarctica, and the salp, Salpa thompsoni. A comparison of total catches among sites revealed that the largest volumetric abundances and biomasses were captured at the Marguerite Bay site.Cluster analysis of abundance data identified distinct multispecies assemblages at Joinville Island in Region I, Croker Passage in Region II, Marguerite Bay in Region III, and Charcot Island in Region IV. A fifth distinct assemblage included samples from sites near Anvers and Renaud Island in Region II, and from the Marguerite Trough in Region III. Assemblages at Joinville Island and Croker Passage were both dominated by E. superba and S. thompsoni, but hydrographic conditions at Joinville Island favored a neritic assemblage, underscored by substantial numbers of P. antarctica. The assemblage at Croker Passage was more oceanic in nature with major inputs from the myctophid, Electrona antarctica and the hyperiid amphipod, Themisto gaudichaudii. Marguerite Bay and Charcot Island were well-mixed assemblages with strong representation by both neritic and oceanic fauna. The mid-peninsula assemblage was oceanic in ...