New Insights into the Distribution, Physiology and Life Histories of South American Galaxiid Fishes, and Potential Threats to This Unique Fauna

Abstract

South American galaxiids occupy both Patagonia and the ichthyogeographic Chilean Province, encompassing glacial Andean deep lakes, shallow plateau lakes, reservoirs, short Pacific rivers and long Atlantic rivers. The total fish fauna includes 29 species, comprising Neotropical fishes (siluriforms and characids), galaxiids, percichthyids, atherinopsids and mugilids, two lamprey species, and several exotic fishes (salmonids, Gambusia spp. and common carp). The family Galaxiidae shares a common ancestry with the Gondwanan temperate fish fauna, played a major role in the post-glacial colonization of Andean lakes and streams, and contributes key species to the food webs. Galaxiid species occupy an enormous latitudinal gradient, show a wide variety of life history patterns and are the southernmost native freshwater fishes of the world. Knowledge of South American galaxiids has improved notably, but new challenges arise due to climate change, biological invasions, damming, aquaculture and contamination. In this changing environment, the future of South American galaxiids should be carefully considered as a legacy of the old Gondwana and a unique attribute of the freshwaters of southern South America.

Variation of stomach content and isotopic niche of puye Galaxias maculatus (Jenyns, 1842) in large river systems of southern Chile

“…This diet may contribute to the better body condition of these fish compared to fish in lakes and estuaries. Fish in this study were sampled in autumn and better condition of larger fish in some populations may be related to their sexual maturity and gonad development for autumn spawning (Cussac et al., 2020). As such, we acknowledge that our results are influenced by the limited sampling that occurred on a single occasion in autumn 2013.…”

“…Galaxias maculatus (Jenyns, 1842), locally referred to as puye in Chile, is a small fish characterised by large geographical range and an ability to adapt to a variety of habitats (Barbee et al., 2011; Cussac et al., 2020; Pollard, 1971). Populations of puye can be found in Australia, New Zealand, Chatham Island, southern Chile, Argentina, and the Falkland Islands (McDowall, 1968; Pollard, 1973).…”

Morphometric Response of Galaxias maculatus (Jenyns) to Lake Colonization in Chile

“…Galaxias maculatus is the most widely distributed diadromous fish in the southern hemisphere. It occurs in rivers and lakes in Australia, New Zealand, and Southern South America (Chile and Argentina) [30][31][32]. As adults, the individuals are small (about 100 mm) and elongate with generally slender bodies [33].…”

“…Although G. maculatus are typically river-dwelling [34], some populations in Chile have become isolated in lakes [31,35,36]. These landlocked populations have little to no gene flow with their original source river populations [32,34,[37][38][39]. This genetic isolation is significant if the variation between populations is based on underlying, heritable differences rather than phenotypic plasticity.…”

Effects of the cranial parasite Tylodelphys sp. on the behavior and physiology of puye Galaxias maculatus (Jenyns, 1842)

“…Specifically, we studied Tylodelphys sp., a recently reported parasite that inhabits the cranial cavity of puye Galaxias maculatus (Jenyns, 1842) ( George-Nascimento, López-Rodríguez & Górski, 2020 ). Puye are freshwater fish commonly found in southern South America in littoral zones of rivers and lakes where they feed ( Cussac et al, 2020 ; Górski et al, 2018 ; Habit et al, 2010 ).…”