Fish from the Southern Ocean: biodiversity, ecology and conservation challenges

• Published in: Frontiers in Marine Science
• Main Author: Marino Vacchi
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2015
• Subjects: Fishes; Biodiversity; Southern Ocean; Antarctica; ecology and conservation; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Antarctic; The Antarctic; Antarc*; Antarctic silverfish; Sea ice
• Online Access: https://doi.org/10.3389/conf.fmars.2015.03.00094; https://doaj.org/article/70652567db50498fadce58fab7db14c6

According to the most recent census, the modern fauna of the Southern Ocean (SO) includes 374 fish species. Among them, a single group of closely related species, the suborder Notothenioidei, dominates, in terms of diversity, biomass and abundance, accounting for 115 or 30.75% of all SO species. The diversification and dominance of notothenioids in the SO is the result of a unique evolutionary history influenced by climatic and oceanographic changes that led to the isolation of the Antarctic continent and the establishment of the modern Antarctic marine environment. Taking advantage by the eradication of previous faunas, over the last 25 million years, notothenioid expanded in a variety of habitats and filled most of the available ecological niches in the frigid and isolated waters of the Antarctic continental shelf and slope. Living and functioning at subzero temperatures implied important adaptations, including freezing avoidance by antifreeze glycoproteins ( AFGPs). Among the system-wide adaptive traits holding major ecological implications, the acquisition of secondary pelagicism in some species (plesiomorphically devoid of swim-bladder) is a major. In those notothenioids, lipid deposition and reduced ossification allowed to achieve partial or full neutral buoyancy, and enabled expansion into semi-pelagic, pelagic, and cryopelagic habitats. Such an impressive ecological expansion has allowed several notothenioids to play a primary role in the Antarctic marine ecosystems. On the other side, their fine adaptation to the environment, might expose these fishes to risks that need to be properly considered and addressed. For instance, a relationship between the Antarctic silverfish (Pleuragramma antarctica), a key species in the coastal Antarctic ecosystem and the sea-ice, has recently been assessed, thus making this species potentially threatened by the ongoing climatic change, with implications for the whole ecosystem. In addition, some Antarctic fish, such as toothfishes (Dissostichus eleginoides and Dissostichus ...