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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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Map of study sites in north-eastern Australia.Location of five study sites in the Wet Tropics of north-eastern Australia. Solid triangles denote where freshwater fish surveys were conducted.
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pone-0026685-g001: Map of study sites in north-eastern Australia.Location of five study sites in the Wet Tropics of north-eastern Australia. Solid triangles denote where freshwater fish surveys were conducted.

Mentions: Five non-adventitious coastal streams in the Wet Tropics of north-eastern Australia were chosen for survey. For the sake of brevity, these streams will be referred to as coastal Wet Tropics streams in this study. Streams were selected for survey based on the following criteria: a small stream order (≤3), a steep gradient, the absence of an extensive estuary, an intact rainforest riparian zone and relatively perennial flows. Streams were selected to encompass the range of catchment sizes that drain these steep coastal ranges (Table 1). Noah Creek, located north of the regional city of Cairns, was the largest catchment investigated (29.8 km2) (Fig. 1). This system drains the northern flank of Thornton Range and has a small lowland component to its catchment which includes a small estuarine zone. Pauls Pocket Creek and Un-named Creek 1 drain the Malbon Thompson range to the south of Cairns. These systems have no significant lowland habitat, however, Pauls Pocket Creek flows into a very small coastal lagoon which remains closed to the ocean during periods of minimal flow. Un-named Creek 2 and Un-named Creek 3 flow off the eastern ridge of the Graham Range to the south of Cairns. Both of these catchments are very small and steep (1.2 km2 and 0.4 km2 respectively) with no lowland/estuarine component. All study streams are in a relatively pristine state with no artificial barriers to flow, although water is abstracted from Un-named Creek 2 for the small coastal community of Russell Heads.


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 study sites in north-eastern Australia.Location of five study sites in the Wet Tropics of north-eastern Australia. Solid triangles denote where freshwater fish surveys were conducted.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0026685-g001: Map of study sites in north-eastern Australia.Location of five study sites in the Wet Tropics of north-eastern Australia. Solid triangles denote where freshwater fish surveys were conducted.
Mentions: Five non-adventitious coastal streams in the Wet Tropics of north-eastern Australia were chosen for survey. For the sake of brevity, these streams will be referred to as coastal Wet Tropics streams in this study. Streams were selected for survey based on the following criteria: a small stream order (≤3), a steep gradient, the absence of an extensive estuary, an intact rainforest riparian zone and relatively perennial flows. Streams were selected to encompass the range of catchment sizes that drain these steep coastal ranges (Table 1). Noah Creek, located north of the regional city of Cairns, was the largest catchment investigated (29.8 km2) (Fig. 1). This system drains the northern flank of Thornton Range and has a small lowland component to its catchment which includes a small estuarine zone. Pauls Pocket Creek and Un-named Creek 1 drain the Malbon Thompson range to the south of Cairns. These systems have no significant lowland habitat, however, Pauls Pocket Creek flows into a very small coastal lagoon which remains closed to the ocean during periods of minimal flow. Un-named Creek 2 and Un-named Creek 3 flow off the eastern ridge of the Graham Range to the south of Cairns. Both of these catchments are very small and steep (1.2 km2 and 0.4 km2 respectively) with no lowland/estuarine component. All study streams are in a relatively pristine state with no artificial barriers to flow, although water is abstracted from Un-named Creek 2 for the small coastal community of Russell Heads.

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