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5 Modeling the Population Consequences of Exposure to Multiple Stressors
Pages 59-68

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From page 59...
... (2014) used the PCoD model structure to • variations in health may affect individual vital rates investigate the potential effects of lost foraging dives on the (the probability of survival, giving birth, or growth/ health (measured by total lipid mass; see Schick et al., 2013)
From page 60...
... used a bioenergetic model and empirical information DEFINING INDIVIDUAL HEALTH on the behavioral response of adult female minke whales (Balaenoptera acutorostrata) to whale-watching boats on Evaluation of the potential demographic impacts on their summer feeding grounds in Iceland to estimate the marine mammal populations of cumulative exposure to effects of these responses on the whales' health (as measured multiple stressors requires the biological upscaling (Cooke by their blubber volume)
From page 61...
... work for a single individual exposed to one stressor. It differs Given this background, an assessment of an individual's from the original PCoD model in the following ways: health provides a useful integration of the way physiological and behavioral responses to multiple stressors may affect that • It can be used to describe the effects of any dosage individual's fitness.
From page 62...
... Examples include of cumulative impacts. reduced immune status, increased long-term levels of stress The effects of multiple stressors may interact internally hormones, and reduced body condition relative to normal to affect allostatic load.
From page 63...
... comprehensive model of cumulative effects. The framework As noted above, the PCoMS framework treats mortality needs to be fleshed out with mathematical functions that from predation and anthropogenic activities (such as bycatch, describe the relationships between the different compartdeliberate killing, and fatal ship strikes)
From page 64...
... valuable marker of the cumulative effect of multiple stressors These relationships could be used as the transfer func- in marine mammals. tions linking the health and individual vital rates compart- Uses of single physiological markers have yielded ments in a PCoMS framework that described the cumulative strong but inconsistent links to individual and population effects of physical injury (resulting from entanglement and fitness.
From page 65...
... Behavior Thus, diving behavior represents a complex interaction of physiological adaptation and the requirements of foraging The most comprehensive information on quantifying and social behaviors. Alterations in behavior in response to exposure-related changes in marine mammal behavior as a disturbance have the potential to create health impacts when function of measured levels of exposure to a stressor come they exceed the constraints imposed by physiology.
From page 66...
... Hematology and serum chemistry parameters are rou tinely used in human health care to assess physiological state and are generally organized into panels that represent specific QUANTIFYING EXPOSURE-RELATED pathological processes or organ systems. In circumstances CHANGES IN INDIVIDUAL HEALTH where blood samples can be collected from marine mammals these measures can provide information on basic metabolic Measures of Body Condition That Are Useful for status, kidney function, inflammation, liver disease, or thyAssessing Health roid disorders.
From page 67...
... all of the primary immune components identified in biomedical studies. However, it is likely that there are modifications Measures of Stress That Are Useful for Assessing Health to marine mammal immune function that serve to preserve response under the diverse environmental conditions expe- One approach to measuring the cumulative physirienced, including high pressure, cold temperatures, and ological impact of multiple stressors on marine mammals is extreme hypoxemia, conditions that are immunosuppressive through the measurement of stress hormones.
From page 68...
... glucocorticoid tial to provide unique insights into the historical variation concentrations can be measured in rapidly acquired blood in stress responses and reproduction. Earplugs from several samples, although this kind of sampling is not feasible for species of large cetaceans provide time series of hormone most species of marine mammals.


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