Approaches to Understanding the Cumulative Effects of Stressors on Marine Mammals (2017) / Chapter Skim
Currently Skimming:
6 Interactions Among Stressors and Challenges to Understanding Their Cumulative Effects
6 Interactions Among Stressors and Challenges to Understanding Their Cumulative Effects
Pages 69-78
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 69... ...
In the third The assessment of aggregate and cumulative effects short section of this chapter, "ecological surprises" are from stressors (anthropogenic or natural) on any particular introduced and discussed as the likely manifestation of what species or stock of marine mammal involves two funda science does not yet understand about the way interaction mental elements: conceptualizing the process by which the webs are assembled and how they function.
|
From page 70... ...
. Interactive effects abiotic environmental elements arrayed around the perimeter might be positive (e.g., the influence of a prey species on its (referred to subsequently as nodes)
|
From page 71... ...
Direct interac- • For a noise effects example, animals are not expecttions are those in which there are no intervening species, ed to respond to sounds at levels below their hearwhereas indirect interactions are those in which there are one ing threshold, and responsiveness may not increase or more intervening species. Indirect effects can link species above a certain high intensity of sound.
|
From page 72... ...
If the slope of this linear relationship is known would be nonlinear, and the form of this function would at low driver levels, this relationship can be extrapolated likely vary between capital and income breeders. to predict effects at higher driver levels.
|
From page 73... ...
The net effects of anthropogenic stressors on of ecological tipping points and regime shifts were based marine mammal populations and their associated ecosystems on theoretical analyses (e.g., Lewontin, 1969; May, 1976)
|
From page 74... ...
entific studies of all kinds. o Eighty-eight percent of those who responded • Ecological surprises are especially common and in the affirmative believed that they understood underreported.
|
From page 75... ...
complex functional relationships in the inter the average value of the intrinsic variation among identiactions among species and between species and the abiotic cally treated experimental units to converge on zero with environment; and (c) overly simplistic views of interaction increased replicate number.
|
From page 76... ...
As noted over whether the purported or hypothesized stressor is the in Chapter 3, the lack of strong evidence for an influence of cause of any marine mammal response in the face of other fisheries on marine mammals through competition for prey potential confounding variables. This fundamental limitation or other indirect interaction web effects is due to the failure to correlative analyses will be greatly magnified in efforts to to be able to assess these effects experimentally.
|
From page 77... ...
(as will be the case for long-lived, slow-reproducing animals Adaptive management involves first setting a conser- like most marine mammals) ; because standard experimental vation objective and then formulating multiple hypotheses practices like replication and blocking are not possible; or about the population response to the different management because the monitoring of outcomes that are feasible is too options, together with an assessment of the probability imprecise to be useful.
|
From page 78... ...
Experimental designs that are capable important outstanding questions are these: For which par- of demonstrating interactive effects while controlling for ticular stressors under what specific conditions and for which confounding influences are nearly impossible to carry out marine mammal species will cumulative effects occur, and without purposely manipulating the purported drivers in an what are the functions that relate stressor dosage to the linked orthogonal manner. A final challenge is in the detection of effect?
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.