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Ecological drivers of shark distributions along a tropical coastline.

Yates PM, Heupel MR, Tobin AJ, Simpfendorfer CA - PLoS ONE (2015)

Bottom Line: In particular, turbid environments were especially important for all species at typical oceanic salinities.Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species.Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

View Article: PubMed Central - PubMed

Affiliation: Centre for Sustainable Tropical Fisheries and Aquaculture and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland, Australia.

ABSTRACT
As coastal species experience increasing anthropogenic pressures there is a growing need to characterise the ecological drivers of their abundance and habitat use, and understand how they may respond to changes in their environment. Accordingly, fishery-independent surveys were undertaken to investigate shark abundance along approximately 400 km of the tropical east coast of Australia. Generalised linear models were used to identify ecological drivers of the abundance of immature blacktip Carcharhinus tilstoni/Carcharhinus limbatus, pigeye Carcharhinus amboinensis, and scalloped hammerhead Sphyrna lewini sharks. Results indicated general and species-specific patterns in abundance that were characterised by a range of abiotic and biotic variables. Relationships with turbidity and salinity were similar across multiple species, highlighting the importance of these variables in the functioning of communal shark nurseries. In particular, turbid environments were especially important for all species at typical oceanic salinities. Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species. Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

No MeSH data available.


Study area.Spatial distribution of longline and gill-net sampling (indicated in black) within the five study bays along tropical north Queensland.
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pone.0121346.g001: Study area.Spatial distribution of longline and gill-net sampling (indicated in black) within the five study bays along tropical north Queensland.

Mentions: This study was conducted within five bays spanning c. 400 km of the tropical north Queensland coastline (Fig. 1): Rockingham, Bowling Green, Upstart, Edgecumbe and Repulse Bays. The bays are shallow (predominantly < 15 m depth) and sheltered from ocean swells by the Great Barrier Reef. As a result, bays were dominated by silty substrates with mudflat or mangrove-lined foreshores. Environmental conditions across the study region were spatially and temporally variable. For example, mangrove extent ranged from c. 29 km2 in Edgecumbe Bay up to c. 205 km2 in Rockingham Bay. The supply of freshwater from rivers typically varied depending on catchment size and the spatial distribution of rainfall [41]. In addition, rainfall was highly seasonal with 60–80% typically occurring during the summer wet season (November–April; [41]).


Ecological drivers of shark distributions along a tropical coastline.

Yates PM, Heupel MR, Tobin AJ, Simpfendorfer CA - PLoS ONE (2015)

Study area.Spatial distribution of longline and gill-net sampling (indicated in black) within the five study bays along tropical north Queensland.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390147&req=5

pone.0121346.g001: Study area.Spatial distribution of longline and gill-net sampling (indicated in black) within the five study bays along tropical north Queensland.
Mentions: This study was conducted within five bays spanning c. 400 km of the tropical north Queensland coastline (Fig. 1): Rockingham, Bowling Green, Upstart, Edgecumbe and Repulse Bays. The bays are shallow (predominantly < 15 m depth) and sheltered from ocean swells by the Great Barrier Reef. As a result, bays were dominated by silty substrates with mudflat or mangrove-lined foreshores. Environmental conditions across the study region were spatially and temporally variable. For example, mangrove extent ranged from c. 29 km2 in Edgecumbe Bay up to c. 205 km2 in Rockingham Bay. The supply of freshwater from rivers typically varied depending on catchment size and the spatial distribution of rainfall [41]. In addition, rainfall was highly seasonal with 60–80% typically occurring during the summer wet season (November–April; [41]).

Bottom Line: In particular, turbid environments were especially important for all species at typical oceanic salinities.Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species.Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

View Article: PubMed Central - PubMed

Affiliation: Centre for Sustainable Tropical Fisheries and Aquaculture and College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland, Australia.

ABSTRACT
As coastal species experience increasing anthropogenic pressures there is a growing need to characterise the ecological drivers of their abundance and habitat use, and understand how they may respond to changes in their environment. Accordingly, fishery-independent surveys were undertaken to investigate shark abundance along approximately 400 km of the tropical east coast of Australia. Generalised linear models were used to identify ecological drivers of the abundance of immature blacktip Carcharhinus tilstoni/Carcharhinus limbatus, pigeye Carcharhinus amboinensis, and scalloped hammerhead Sphyrna lewini sharks. Results indicated general and species-specific patterns in abundance that were characterised by a range of abiotic and biotic variables. Relationships with turbidity and salinity were similar across multiple species, highlighting the importance of these variables in the functioning of communal shark nurseries. In particular, turbid environments were especially important for all species at typical oceanic salinities. Mangrove proximity, depth, and water temperature were also important; however, their influence varied between species. Ecological drivers may promote spatial diversity in habitat use along environmentally heterogeneous coastlines and may therefore have important implications for population resilience.

No MeSH data available.