Summer survey of dugong distribution and abundance in Shark Bay reveals additional key habitat area

Holley, David; Lawler, Ivan R.; Gales, Nicholas J.

doi:10.1071/wr05031

Cited by 24 publications

(27 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First, seasonal movements are correlated to temperature changes [2], [54]–[56]. Second, dugongs seem to move further southwards along the east coast of Australia in warm years [57].…”

Section: Discussionmentioning

confidence: 99%

Mortality of Inshore Marine Mammals in Eastern Australia Is Predicted by Freshwater Discharge and Air Temperature

Meager

Limpus

2014

PLoS ONE

View full text Add to dashboard Cite

Understanding environmental and climatic drivers of natural mortality of marine mammals is critical for managing populations effectively and for predicting responses to climate change. Here we use a 17-year dataset to demonstrate a clear relationship between environmental forcing and natural mortality of inshore marine mammals across a subtropical-tropical coastline spanning a latitudinal gradient of 13° (>2000 km of coastline). Peak mortality of inshore dolphins and dugongs followed sustained periods of elevated freshwater discharge (9 months) and low air temperature (3 months). At a regional scale, these results translated into a strong relationship between annual mortality and an index of El Niño-Southern Oscillation. The number of cyclones crossing the coastline had a comparatively weak effect on inshore marine mammal mortality, and only in the tropics. Natural mortality of offshore/migratory cetaceans was not predicted by freshwater discharge, but was related to lagged air temperature. These results represent the first quantitative link between environmental forcing and marine mammal mortality in the tropics, and form the basis of a predictive tool for managers to prepare responses to periods of elevated marine mammal mortality.

show abstract

“…First, seasonal movements are correlated to temperature changes [2], [54]–[56]. Second, dugongs seem to move further southwards along the east coast of Australia in warm years [57].…”

Section: Discussionmentioning

confidence: 99%

Mortality of Inshore Marine Mammals in Eastern Australia Is Predicted by Freshwater Discharge and Air Temperature

Meager

Limpus

2014

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…Case study 3:— Use of alternative foraging tactics by dugongs ( Dugong dugon ) in Shark Bay —Shark Bay is home to over 10,000 dugongs (Holley et al . 2006), many of which make use of our study area (> Wirsing et al .…”

mentioning

confidence: 99%

Seascapes of fear: evaluating sublethal predator effects experienced and generated by marine mammals

Wirsing

Heithaus

Frid³

et al. 2007

Marine Mammal Science

158

129

View full text Add to dashboard Cite

The notion that predators can affect their prey without killing them is widely supported in the ecological literature yet rarely applied by marine mammal studies. We present three case studies in which patterns of time allocation by individual marine mammal foragers were used to index the sublethal effects of predators on bottlenose dolphins (Tursiops sp.), harbor seals (Phoca vitulina), and dugongs (Dugong dugon). In each case, foraging individuals optimized energy gain and safety from predators by spending less time in more profitable but dangerous patches or decreasing their use of risky feeding tactics that would increase net energy gain. By implication, marine mammals are subject to the non consumptive effects of their predators (i.e., to intimidation), and fear can mediate their impacts on their resources. We suggest, therefore, that future studies quantify patterns of time allocation to measure sublethal effects of predators on marine mammals, as well as the capacity of marine mammals to have sublethal effects on their own prey. We argue that such an approach is important because non consumptive effects may be of greater magnitude than lethal effects of predators, and information on sublethal effects of predators can inform conservation plans and studies of community structure.

show abstract

“…At the higher latitude limits of their range in summer, dugongs are most frequently sighted over shallow seagrass meadows, but in winter they are also sighted in deeper waters where sea temperatures are warmer ( e.g ., Preen , Lanyon , Holley et al . , Sheppard et al . , Marsh et al .…”

Section: Discussionmentioning

confidence: 99%

Improving population estimates by quantifying diving and surfacing patterns: A dugong example

Hagihara

Jones

Grech

et al. 2013

Marine Mammal Science

View full text Add to dashboard Cite

Diving animals are available for detection from above the water when environmental conditions are favorable and the animals are near the surface. The number of animals that are unavailable for detection needs to be estimated to obtain unbiased population estimates. The current availability correction factors used in aerial surveys for the dugong (Dugong dugon) allow for variation in environmental conditions but use the average time dugongs spend near the surface (i.e., constant availability corrections). To improve availability estimates, we examined location and dive data from nine dugongs fitted with satellite telemetry units and time‐depth recorders (TDRs) in eastern Australia. The effects of water depth, tidal conditions, and habitat types on dugong surfacing time were examined using generalized linear mixed models (GLMMs). We found that availability for detection differed with water depth, and depth‐specific availability estimates were often lower than the constant estimates. The habitat effect was less influential, and there was no tidal effect. The number of dugongs estimated using depth‐specific availabilities were higher than those obtained using constant availabilities across water depth. Hence, information on water depth can refine availability estimates and subsequent abundance estimates from dugong aerial surveys. The methodology may be applicable to other aquatic wildlife.

show abstract

Summer survey of dugong distribution and abundance in Shark Bay reveals additional key habitat area

Cited by 24 publications

References 19 publications

Mortality of Inshore Marine Mammals in Eastern Australia Is Predicted by Freshwater Discharge and Air Temperature

Mortality of Inshore Marine Mammals in Eastern Australia Is Predicted by Freshwater Discharge and Air Temperature

Seascapes of fear: evaluating sublethal predator effects experienced and generated by marine mammals

Improving population estimates by quantifying diving and surfacing patterns: A dugong example

Contact Info

Product

Resources

About