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3 How to Get From Acoustic Disturbance to Population Effects
Pages 35-68

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From page 35...
... The fourth transfer function relates changes in the vital rates of individuals to population effects. Current data are insufficient to allow the PCAD model to serve as more than a conceptual model, so the listing of data at the first three levels -- involving sound characteristics, behaviors, and life functions -- is exemplary rather than all-inclusive.
From page 36...
... 36 + Duty Source Le Dur SOUND + Frequency + ation cycle vel + 1 + Av Mother-inf Resting Diving Breathing Or CHANGE BEHA + relationships spatial- Vocalization oidance ientation VIOR ant + 2 Response Nur Breeding Mig Sur AFFECTED IMMEDIA LIFE + predator Feeding tur ration viv ing al FUNCTION TEL to Y 0 3 + Reproduction Matur Sur Stage VIT viv AL ation al specific RA TES +++ 4 + Extinction Elasticity Sensitivity Tr POPULA ansient Population Population probability dynamics TION str ucture growth EFFECT rate FIGURE 3-1
From page 37...
... Five groups of variables are of interest, and transfer functions specify the relationships between the variables listed, for example, how sounds of a given frequency affect the vocalization rate of a given species of marine mammal under specified conditions. Each box lists variables with observable features (sound, behavior change, life function affected, vital rates, and population effect)
From page 38...
... . This could allow the development of mathematical models that predict the levels and types of noise that pose a risk of injury or behavioral disturbance to marine mammals.
From page 39...
... · Absolute sensitivity · Temporal integration function · Nonauditory biological effects · Biologically significant behaviors with the potential to change demographic parameters such as mortality and reproduction. Modified from NRC (2000)
From page 40...
... For marine mammals, data are available on only a few sounds and a few behaviors in a few species. Observational and correlational studies can provide trend data, and expertopinion modeling can provide at least a "lookup" table to serve as a surrogate for this transfer function (Andelman et al., 2001)
From page 41...
... That makes demographic models a powerful tool for placing bounds on likely effects, for exploring the quantitative implications of hypothesized interactions, and for synthesizing what is currently known. Establishing acceptable population effects is a management question that has already received a good deal of attention.
From page 42...
... Development of such a model will allow sensitivity analysis that can be used to focus, stimulate, and direct research on appropriate transfer functions. In addition to research studies designed to evaluate reactions of marine mammals to noise, limited information is available from monitoring pro
From page 43...
... However, if those short-term measures are selected purely for ease of observation, it will often be difficult to link the responses to the functional categories described in the PCAD model, a link that is essential for extrapolating short-term measures to long-term effects that would alter some life function of an individual animal. Federal regulators for the last several decades have required monitoring programs instead of targeted research on the assumption that monitoring would detect developing problems.
From page 44...
... off Sakhalin Island, Russia, illustrate the potential for anthropogenic sound to have a severe impact on a marine mammal population. The western gray whale is critically endangered, numbering about 100, and depends on the north eastern Sakhalin Island feeding ground for most of its food intake.
From page 45...
... Current data on physiological or behavioral effects of well-studied marine mammals would not have suggested such a risk to poorly known beaked whales. The recent cases of the association of beaked whale strandings with naval sonar stimulated a review of prior records of beaked whale mass stranding events (Brownell et al., 2004; Taylor et al., 2004)
From page 46...
... Federal agencies with responsibility for managing marine mammal populations conduct intramural research that often ends up as unpublished reports that contain valuable information. For example, NOAA Fisheries conducts surveys for assessing the status of marine mammal stocks.
From page 47...
... All data entered into such an integrated data base must be coded as to quality, and peer-reviewed data and interpretations should be rated highest. DATA NEEDED TO DETERMINE PHYSIOLOGICAL RESPONSES TO ACOUSTIC STIMULI Immediate behavioral responses are the easiest to observe, but the population consequences of sound will be modulated through physiological responses.
From page 48...
... Physiological Stress Effects Anthropogenic sound is a potential source of stress in marine mammals, and it has been shown to increase blood pressure and catecholamine and cortisol concentrations in humans (Evans et al., 1995; Evans et al., 2001; Ising and Kruppa, 2004)
From page 49...
... (d) In more naturally fluctuating conditions, type 1 allostatic overload may occur first or more rapidly if a perturbation occurs during a season when the conditions are worse.
From page 50...
... An allostatic state can be maintained for some time if environmental resources are sufficient. However, the cumulative result of an organism's allostatic state is its "allostatic load." The usual allostatic load results from the organism's need to obtain enough food to survive plus any extra energy required for normal seasonal activities, such as migrating, molting, mating, and lactating.
From page 51...
... , must balance their energy budgets on much shorter periods -- months to days. Thus, energy considerations suggest that sound disturbance could severely affect the energy budget of baleen whales if it displaced them from their feeding grounds for a substantial fraction of the feeding season but would be less likely to have a serious effect on energy needs if it occurred in other circumstances, such as during migration, and merely displaced them temporarily from their normal migratory path.
From page 52...
... . Thus, energy considerations suggest that small otariid species could be affected rather quickly by anthropogenic noise close to their rookeries if it interrupted normal foraging whereas larger species that were not foraging during lactation would be more likely to meet their and their pups' energy needs in the presence of a similar disturbance.
From page 53...
... Determining the time for various marine mammals will identify the extent to which this technique can be applied usefully, at least in situations where capture for blood sampling is feasible. In most cases, capture of marine mammals for blood sampling will be impossible.
From page 54...
... a programmed schedule. More recently, sophisticated data logger tags have been attached to marine mammals to study their responses to anthropogenic sounds (Burgess, 2001; Johnson and Tyack, 2003)
From page 55...
... Concentrations of fecal progestins are increasingly used in research and conservation for assessing pregnancy in terrestrial mammals. Application to marine mammals to evaluate pregnancy rates and fetal or early infant loss may be relatively straightforward (Larson et al., 2003)
From page 56...
... DATA NEEDED TO DESCRIBE MARINE MAMMAL POPULATIONS To understand the behavioral effect that a sound may have in a given place and at a given time, it is necessary to be able to answer the following questions:
From page 57...
... That data gap could be addressed by completing basic behavioral ecological studies of marine mammals in the wild. To understand the biological significance of behavioral disruption, a greatly accelerated program is needed for studying the behavior and ecology of marine mammals in the wild, with a focus on how variation in behavior may affect probabilities of survival, growth, and reproduction in different ecological settings.
From page 58...
... . Predictive modeling to determine the population effects of noise on marine mammals is therefore not now an option.
From page 59...
... The way that they propose using models in Areas 2 and 4 is philosophically akin to Tukey's exploratory data analysis; that is why the term exploratory modeling is used.
From page 60...
... For example, we know that responses can be situation-specific. It has already been noted that the responses of migrating gray whales depend on whether a low-frequency active source is in the migratory path or a few kilometers seaward of the migratory path even though the received levels were similar (Tyack and Clark, 2000)
From page 61...
... Demographic Models The most well-developed and widely used approach to population modeling is that of age-structured demographic analysis. A demographic model is one that categorizes individuals into groups based on biological characteristics relevant to their survival and reproduction.
From page 62...
... , only the most fragmentary data were available -- both studies used demographic models to place bounds on population growth, to speculate on the outcome of hypothesized interactions, and to synthesize sparse data. More recent examples of exploratory use of demographic models include the exploration of management strategies for sea turtles (Crouse et al., 1987)
From page 63...
... For example, the Acoustic Integration Model (AIM; Frankel et al., 2002) models the location and dive behavior of simulated marine mammals swimming near a modeled acoustic source.
From page 64...
... Such a model may separate the consequences of an effect from the probability that it will occur. It could be developed with a combination of available information on marine mammals, information on comparable nonmarine mammals selected on the basis of life-history scaling or body-size scaling, first principles, and expert opinion (Morgan and Henrion, 1990; Goodwin and Wright, 1991; Meyer and Booker, 1991; Anderson, 1998; Andelman et al., 2001)
From page 65...
... Expert Opinion Data on many links in the chain from acoustic stimuli to population effects on marine mammal populations are sparse or lacking. Therefore, regulators such as NOAA Fisheries and the US Fish and Wildlife Service (FWS)
From page 66...
... . If relevant data on marine mammals are lacking, this kind of simulation approach can benefit from the use of data on other species selected on the basis of life history, ecology, or body size (e.g., Caswell et al., 1998)
From page 67...
... RECOMMENDATION 5: Several marine mammal species for which there are good long-term demographic and behavioral data on individuals should be selected as targets of an inten sive exploratory modeling effort that would develop a series of individual-based models and stage- or age-structured demo graphic models for the species as appropriate. NOAA Fisheries should bring together an independent, interdisciplinary panel of modelers and relevant empirical scientists that would meet periodically to pursue the modeling effort collaboratively in an iterative and adaptive manner with the long-term goal of developing tools to support informed, practical decision making.
From page 68...
... . All those have been studied extensively, and individual animals have been identified and resighted over multiple years.


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