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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.


Related in: MedlinePlus

Relative importance of ecological variables.Parameters are listed according to mean Relative Variable Importance (RVI) across all species/sampling-method combinations. Parameters that were ubiquitous within the confidence set (i.e. models with ΔAIC < 2) have a RVI value of 1.0. The numbers of models included in model averaging are provided in parentheses.
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pone.0121346.g003: Relative importance of ecological variables.Parameters are listed according to mean Relative Variable Importance (RVI) across all species/sampling-method combinations. Parameters that were ubiquitous within the confidence set (i.e. models with ΔAIC < 2) have a RVI value of 1.0. The numbers of models included in model averaging are provided in parentheses.

Mentions: Variation in shark abundance was associated with complex combinations of main effects and interactions. Overall, turbidity and salinity were the most influential variables on shark abundance (Fig. 3). Most notably, excluding blacktip sharks on longlines, turbidity was present in all best-performing models (i.e. those with ΔAIC < 2; Table 3). Mangrove proximity, depth and water temperature were also important however their influence varied between species.


Ecological drivers of shark distributions along a tropical coastline.

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

Relative importance of ecological variables.Parameters are listed according to mean Relative Variable Importance (RVI) across all species/sampling-method combinations. Parameters that were ubiquitous within the confidence set (i.e. models with ΔAIC < 2) have a RVI value of 1.0. The numbers of models included in model averaging are provided in parentheses.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0121346.g003: Relative importance of ecological variables.Parameters are listed according to mean Relative Variable Importance (RVI) across all species/sampling-method combinations. Parameters that were ubiquitous within the confidence set (i.e. models with ΔAIC < 2) have a RVI value of 1.0. The numbers of models included in model averaging are provided in parentheses.
Mentions: Variation in shark abundance was associated with complex combinations of main effects and interactions. Overall, turbidity and salinity were the most influential variables on shark abundance (Fig. 3). Most notably, excluding blacktip sharks on longlines, turbidity was present in all best-performing models (i.e. those with ΔAIC < 2; Table 3). Mangrove proximity, depth and water temperature were also important however their influence varied between species.

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.


Related in: MedlinePlus