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Amphidromy links a newly documented fish community of continental Australian streams, to oceanic islands of the west Pacific.

Thuesen PA, Ebner BC, Larson H, Keith P, Silcock RM, Prince J, Russell DJ - PLoS ONE (2011)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Marine and Tropical Biology, James Cook University, Cairns, Queensland, Australia. paul.thuesen@gmail.com

ABSTRACT

Background: Indo-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 findings: Surveys 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/significance: Coastal 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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Related in: MedlinePlus

Map of the West Pacific freshwater fish communities used in analyses.Map indicating the Wet Tropics of north-eastern Australia, in relation to Papua New Guinea and West Pacific island groups. Open circles denote regions were freshwater fish communities were included for analyses.
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pone-0026685-g002: Map of the West Pacific freshwater fish communities used in analyses.Map indicating the Wet Tropics of north-eastern Australia, in relation to Papua New Guinea and West Pacific island groups. Open circles denote regions were freshwater fish communities were included for analyses.

Mentions: First, the fish community data collected from 1) coastal Wet Tropics streams (CWTS) were compared with detailed presence/absence lists from 2) West Pacific island streams (WPIS) (Fig. 2) [2], [31], [32], [33], [34] (data also supplemented from www.fishbase.org), 3) Wet Tropics rivers (stream order ≥5) (WTR) [35] and 4) Papua New Guinea Rivers (PNGR) [36], [37]. It could be argued that a large dissimilarity in community structure was expected in the latter two comparisons, due to the dichotomy in physical size between the study streams and these larger continental rivers. Therefore, to control for these size differences, the fish community of coastal Wet Tropics streams was also compared to 5) Wet Tropics streams which drain into large rivers (WTS) [38], [39]. These adventitious coastal streams were of a similar magnitude in terms of physical size (stream order ≤3), steep gradient, substrate, flow and intactness to CWTS, but differ in that they flowed into larger rivers (stream order ≥5) with a significant estuarine zone. Unfortunately, an equivalent comparison could not be replicated for streams of Papua New Guinea rivers, as only species lists of entire catchments could be sourced from the literature. Only species which were known to have an obligate freshwater component to their life history were included in the analysis.


Amphidromy links a newly documented fish community of continental Australian streams, to oceanic islands of the west Pacific.

Thuesen PA, Ebner BC, Larson H, Keith P, Silcock RM, Prince J, Russell DJ - PLoS ONE (2011)

Map of the West Pacific freshwater fish communities used in analyses.Map indicating the Wet Tropics of north-eastern Australia, in relation to Papua New Guinea and West Pacific island groups. Open circles denote regions were freshwater fish communities were included for analyses.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198781&req=5

pone-0026685-g002: Map of the West Pacific freshwater fish communities used in analyses.Map indicating the Wet Tropics of north-eastern Australia, in relation to Papua New Guinea and West Pacific island groups. Open circles denote regions were freshwater fish communities were included for analyses.
Mentions: First, the fish community data collected from 1) coastal Wet Tropics streams (CWTS) were compared with detailed presence/absence lists from 2) West Pacific island streams (WPIS) (Fig. 2) [2], [31], [32], [33], [34] (data also supplemented from www.fishbase.org), 3) Wet Tropics rivers (stream order ≥5) (WTR) [35] and 4) Papua New Guinea Rivers (PNGR) [36], [37]. It could be argued that a large dissimilarity in community structure was expected in the latter two comparisons, due to the dichotomy in physical size between the study streams and these larger continental rivers. Therefore, to control for these size differences, the fish community of coastal Wet Tropics streams was also compared to 5) Wet Tropics streams which drain into large rivers (WTS) [38], [39]. These adventitious coastal streams were of a similar magnitude in terms of physical size (stream order ≤3), steep gradient, substrate, flow and intactness to CWTS, but differ in that they flowed into larger rivers (stream order ≥5) with a significant estuarine zone. Unfortunately, an equivalent comparison could not be replicated for streams of Papua New Guinea rivers, as only species lists of entire catchments could be sourced from the literature. Only species which were known to have an obligate freshwater component to their life history were included in the analysis.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: School of Marine and Tropical Biology, James Cook University, Cairns, Queensland, Australia. paul.thuesen@gmail.com

ABSTRACT

Background: Indo-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 findings: Surveys 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/significance: Coastal 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.

Show MeSH
Related in: MedlinePlus