Climate change and conservation of endemic amphidromous fishes in Hawaiian streams

Abstract

Amphidromous fishes are important members of oceanic island freshwater communities. Although often depauperate, amphidromous fish assemblages on islands are largely composed of endemic species. Little is known about the effects of anthropogenic stressors on amphidromous fishes, and the consequences of climate-driven changes in water quality and quantity are particularly uncertain. Focusing on native fishes in Hawaii, we discuss the potential for climate change to intensify 3 major threats facing amphidromous fish: (1) loss of 'ridge-to-reef' migratory corridors via disruption of surface water connectivity, (2) in-stream habitat degradation and (3) exotic species introductions. Successfully addressing these and other threats to native fish in Hawaii will require approaches that balance conservation needs with use of water resources. Conservation initiatives should focus on 'scaling up' ongoing projects intended to demonstrate how stream protection and restoration, non-native species removal and reintroductions can benefit at-risk species. Research initiatives should focus on determining the ecological controls on recruitment under current and future climate conditions. KEY WORDS: Amphidromy · Climate change · Freshwater fishes · Hawaii · Ocean−stream connectivity Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Endangered river fish: threats and conservation options'

Parasitism of a native Hawaiian stream fish by an introduced nematode increases with declining precipitation across a natural rainfall gradient

“…In facultative amphidromous species, larvae may remain in freshwater or nearshore environments (Hogan et al 2014). Here, we focused on the facultative amphidromous goby A. stamineus because the species exhibits the broadest in-stream distribution and relative tolerance to degraded condition, which permitted sampling of fishes in multiple reaches across each watershed without risk of detrimental effects on local populations (Fitzsimons et al 2002;Walter et al 2012;Blum et al 2014).…”

Endangered river fish: factors hindering conservation and restoration

“…Diadromous fish require migration corridors that extend from sea to river (e.g. Hasler et al 2011, Jepsen et al 2012, Mateus et al 2012, Walter et al 2012, all this Theme Section). In addition, even small-bodied, pelagic fishes may need at least 100 to 300 river km to sustain populations (Perkin & Gido 2011).…”

“…For example, Baisez et al (2011) documented significant delays and mortality associated with high river temperatures for upstream migrating Atlantic salmon. Walter et al (2012) advocate research efforts to identify the hydrological conditions necessary to positively impact fish recruitment under future climate conditions. In some jurisdictions, efforts have been made to predict the effects of development activities (e.g.…”

Pelagic larval traits of the amphidromous gobySicyopterus lagocephalusdisplay seasonal variations related to temperature in La Réunion Island

“…temperature, current, food availability). After recruiting in river, the juveniles are subject to heavy anthropogenic pressures that often disturb the aquatic systems of tropical islands (Walter et al 2012). Hoareau et al (2007a) showed that newly recruited larvae are aged between 133 and 266 days in La R eunion, whereas those of Pacific areas spend only 131 AE 3.4 days in the sea (Lord et al 2010).…”