Seagrass monitoring by underwater videography: disturbance regimes, sampling design, and statistical power (CROSBI ID 549916)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Schultz, Stewart
engleski
Seagrass monitoring by underwater videography: disturbance regimes, sampling design, and statistical power
Marine flowering plants ("seagrasses") are economically and ecologically valuable communities that are undergoing losses in response to anthropgenic activity worldwide. Precise quantification of such losses before they become large and irreversible is necessary for informed scientific management of these valuable resources. This paper is intended as a step towards designing a seagrass monitoring approach capable of 10% loss detection that is feasible under a variety of disturbance regimes and over a useful range of spatial scales. Surface-based underwater videographic field surveys tracked by differential global positioning systems (DGPS) has several useful characteristics, including its high visual resolution, non-destructive sampling, and its applicability to subtidal species at depths where aerial photography is unable to reliably detect losses seen in many species. Within the specific constraints of a surface-based videographic assay of a seagrass meadow, two basic sampling issues need to be addressed: how is statistical power affected by length of region sampled per random start point, and by an unpaired or paired (repeated measures) sampling design within a single meadow? Here I investigate the statistical power of this method applied to a natural meadow and to virtual meadows created by a spatially explicit model of seagrass disturbance, regrowth, and colonization. The approach is found to detect a 5-10% short term loss at 95% probability, with a sampling design emphasizing long transects (400-1500 m) and analysis in which transects are paired before and after disturbance. A field effort function shows that this precision is possible within a single working field day for 1-km² sampling regions. Surface-based videography is a powerful monitoring tool that can provide managers with precise and timely knowledge of small changes in seagrass cover.
seagrass ; monitoring ; videography ; DGPS
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Podaci o prilogu
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2008.
objavljeno
Podaci o matičnoj publikaciji
Second International Symposium on Environmental Management
Podaci o skupu
Nepoznat skup
predavanje
29.02.1904-29.02.2096