Discovery of stream-cling-goby assemblages (Stiphodon species) in the Australian Wet Tropics

BackgroundIndo-Pacific high island streams experience extreme hydrological variation, and are characterised by freshwater fish species with an amphidromous life history. Amphidromy is a likely adaptation for colonisation of island streams following stochastic events that lead to local extirpation. In the Wet Tropics of north-eastern Australia, steep coastal mountain streams share similar physical characteristics to island systems. These streams are poorly surveyed, but may provide suitable habitat for amphidromous species. However, due to their ephemeral nature, common non-diadromous freshwater species of continental Australia are unlikely to persist. Consequently, we hypothesise that coastal Wet Tropics streams are faunally more similar, to distant Pacific island communities, than to nearby faunas of large continental rivers.Methods/Principal FindingsSurveys of coastal Wet Tropics streams recorded 26 species, 10 of which are first records for Australia, with three species undescribed. This fish community is unique in an Australian context in that it contains mostly amphidromous species, including sicydiine gobies of the genera Sicyopterus, Sicyopus, Smilosicyopus and Stiphodon. Species presence/absence data of coastal Wet Tropics streams were compared to both Wet Tropics river networks and Pacific island faunas. ANOSIM indicated the fish fauna of north-eastern Australian coastal streams were more similar to distant Pacific islands (R = 0.76), than to nearby continental rivers (R = 0.98).Main Conclusions/SignificanceCoastal Wet Tropics streams are faunally more similar to distant Pacific islands (79% of species shared), than to nearby continental fauna due to two factors. First, coastal Wet Tropics streams lack many non-diadromous freshwater fish which are common in nearby large rivers. Second, many amphidromous species found in coastal Wet Tropics streams and Indo-Pacific islands remain absent from large rivers of the Wet Tropics. The evolutionary and conservation significance of this newly discovered Australian fauna requires clarification in the context of the wider amphidromous fish community of the Pacific.

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“…from Thuesen [23], [24], Ebner & Thuesen [25] and current study. # Species shared with Pacific island groups.…”

Section: Resultsmentioning

confidence: 96%

“…The current study, along with a small pilot study [25] has added significantly to the number of freshwater fish recorded in Australia, and specifically in the north-eastern Wet Tropics (increased 15% from 56 species to 67 species). Of the 67 native freshwater fish species (i.e.…”

Section: Discussionmentioning

confidence: 97%

Amphidromy Links a Newly Documented Fish Community of Continental Australian Streams, to Oceanic Islands of the West Pacific

Thuesen

Ebner

Larson³

et al. 2011

PLoS ONE

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“…Functional links between community structure and patterns of flow have highlighted the potential role that high annual base flows may play in maintaining species diversity in these tropical coastal streams. Although overharvesting of some gobies for the aquarium trade may put these species at risk (Ebner & Thuesen, 2011; e.g. national listing of Stiphodon semoni as critically endangered in Australia), flow alteration arising from climate change and/or human activities could also be considered a serious threat (Xenopoulos et al.…”

Section: Discussionmentioning

confidence: 99%

Flow velocity underpins microhabitat selection by gobies of the Australian Wet Tropics

2013

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Summary 1. Water flow is a critical driver of aquatic ecosystem health and function. Amid rising concerns over changing flow regimes, there is an urgent need to understand the functional mechanisms by which flow influences patterns of freshwater biodiversity. 2. We explored the functional link between flow velocity and microhabitat specialisation in a speciose group of freshwater gobies (comprising over half the total fish species richness) within insular streams of the Australian Wet Tropics under base flow conditions. We addressed two particular questions: (i) What is the relative selectivity of species towards streambed composition and water flow velocity? and (ii) Can patterns of microhabitat occupation be explained by differences in intrinsic flow performance among species? To answer these questions, we combined visual field observations of microhabitat use with flow tank assessments of flow speed performance. 3. Tropical freshwater gobies displayed strong specificity towards flow velocities, while being relatively non‐selective towards streambed composition. At opposite extremes of the spectrum, we found Sicyopterus lagocephalus occupying high‐flow (>1.0 ms−1) microhabitats while Redigobius bikolanus selected slower‐flow (<0.05 ms−1) areas. These patterns of microhabitat flow specificity were largely explained by the different abilities of species to swim and/or cling to the substratum under these different flow settings. 4. Our findings confirm suggestions that predictable base flows in tropical streams support habitat specialists, which include one species capable of occupying areas of extremely high flow that very few other fishes can withstand. 5. The functional link between flow and gobioid fish distribution patterns could occur throughout tropical streams of the Indo‐Pacific and Caribbean as a widespread phenomenon that may help inform stream flow management guidelines to maintain this substantial component of tropical freshwater biodiversity around the globe.

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“…Electrofishing has been widely used to survey fishes in north-eastern and temperate Australia (Gehrke & Harris, 2000;Kennard et al ., 2006;Stewart-Koster et al ., 2007;Ebner et al ., 2008). Direct observation from the surface or by snorkelling has also sometimes been used to survey freshwater fishes in Australian systems (Bishop et al ., 1995;Hattori & Warburton, 2003;Morgan & Gill, 2004;Hardie et al ., 2006;Ebner et al ., 2009Ebner et al ., , 2011Ebner & Thuesen, 2010;Thuesen et al ., 2011), although turbidity and the threat of attack by crocodiles and bull sharks Carcharhinus leucas (Müller & Henle 1839) make underwater surveys undesirable in much of the tropics. Permanently turbid or sporadically turbid waterholes are characteristic of most catchments within central and northern Australia (McGregor et al ., 2006), thwarting the widespread application of visual-based survey techniques.…”

Section: Introductionmentioning

confidence: 99%

Using remote underwater video to estimate freshwater fish species richness

Ebner

Morgan

2013

Journal of Fish Biology

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Species richness records from replicated deployments of baited remote underwater video stations (BRUVS) and unbaited remote underwater video stations (UBRUVS) in shallow (<1 m) and deep (>1 m) water were compared with those obtained from using fyke nets, gillnets and beach seines. Maximum species richness (14 species) was achieved through a combination of conventional netting and camera-based techniques. Chanos chanos was the only species not recorded on camera, whereas Lutjanus argentimaculatus, Selenotoca multifasciata and Gerres filamentosus were recorded on camera in all three waterholes but were not detected by netting. BRUVSs and UBRUVSs provided versatile techniques that were effective at a range of depths and microhabitats. It is concluded that cameras warrant application in aquatic areas of high conservation value with high visibility. Non-extractive video methods are particularly desirable where threatened species are a focus of monitoring or might be encountered as by-catch in net meshes.

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Discovery of stream-cling-goby assemblages (Stiphodon species) in the Australian Wet Tropics

Cited by 14 publications

References 17 publications

Amphidromy Links a Newly Documented Fish Community of Continental Australian Streams, to Oceanic Islands of the West Pacific

Amphidromy Links a Newly Documented Fish Community of Continental Australian Streams, to Oceanic Islands of the West Pacific

Flow velocity underpins microhabitat selection by gobies of the Australian Wet Tropics

Using remote underwater video to estimate freshwater fish species richness

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