Fish assemblage dynamics in an intermittent river of the northern Australian wet–dry tropics

Abstract

Intermittent rivers make up a large portion of the global river network and are the dominant river type in northern Australia. Increased pressure is being placed on such systems, and a better understanding of their ecology is needed. We examined, over a 7‐year period, the fish fauna of the intermittent Fergusson River, a major tributary of the Daly River of the northern Australia. Changes in habitat structure with the onset of the dry season involved contraction of the riffle/run/pool habitat to a single refugial pool, the size of which was determined by antecedent wet season hydrology. The fishes present comprised a subset of species present within the Daly River main channel and consisted of the most widely distributed of northern Australia's freshwater fishes. The Fergusson River provides suitable spawning habitat for species during the wet season (e.g. Hephaestus fuliginosus, Leiopotherapon unicolor and Neosilurus catfishes) and during the dry season for a different set of species (e.g. Amniataba percoides, Melanotaenia australis and Glossogobius aureus). Little year‐to‐year variation in assemblage structure was observed early in the dry season, whereas interannual variation in late dry season assemblages was substantial. Dry season recruitment imparted some of the interannual variability in assemblage structure recorded between late dry season samples. Piscivorous fishes were an important, but temporally variable, component of the assemblage present in the late dry season refugial habitat, and predation was potentially another important source of variation in assemblage structure.

Biodiversity value of remnant pools in an intermittent stream during the great California drought

“…This is similar to values observed in other Mediterranean‐climate systems (Magalhâes et al, ; Pires et al, ; Vardakas et al, ) and semiarid systems (Arthington, Balcombe, Wilson, Thoms, & Marshall, ; Beesley & Prince, ), but much lower than the fish species richness documented from intermittent streams in the wet–dry tropics (e.g. 20–30 species: Minshull, ; Pusey, Kennard, Douglas, & Allsop, ). The dominance of native fishes at Coyote Creek may be in large part the result of seasonal drying and habitat contraction to which non‐native species are not adapted.…”

Dynamic contributions of intermittent and perennial streams to fish beta diversity in dryland rivers

“…By examining separate stream components based on flow intermittence and species components based on origin (native or non‐native), we exposed underlying changes in diversity patterns that would otherwise not have been apparent. We found that native species often played a greater role than non‐native species in contributing to beta diversity in intermittent streams, indicating intermittent streams represent important habitats to support local native fish persistence and contribute to maintaining regional diversity through time (Datry, Moya, Zubieta, & Oberdorff, ; Pusey, Kennard, Douglas, & Allsop, ). Fluctuations in river flow due to annual or seasonal hydrologic events (e.g.…”

Effects of adoption of freshwater residency on life‐history ecology of terapontid grunters

“…Extremely seasonal wet season flows create an expanded array of habitat but also act as a disturbance (Stewart‐Koster et al, 2011) and can be both a source of mortality and recruitment. Pronounced intermittency, which is the dominant characteristic of most northern rivers (Kennard et al, 2010), similarly creates opportunities for recruitment while flows persist but prove inimical when they cease (Pusey, Kennard, Douglas, & Allsop, 2016). It is not without significance that northern Australia's most widely distributed fish, L. unicolor , is characteristic of intermittent streams (Pusey et al, 2017).…”