http://www.biomedcentral.com/1472-6785/14/14
Qamar A Schuyler, Chris Wilcox, Kathy Townsend, B Hardesty, N Marshall
Mistaken identity? Visual similarities of marine debris to natural prey
items of sea turtles
BMC Ecology 2014, 14:14 (9 May 2014)
doi:10.1186/1472-6785-14-14
Abstract
Background
There are two predominant hypotheses as to why animals ingest plastic:
1) they are opportunistic feeders, eating plastic when they encounter
it, and 2) they eat plastic because it resembles prey items. To assess
which hypothesis is most likely, we created a model sea turtle visual
system and used it to analyse debris samples from beach surveys and from
necropsied turtles. We investigated colour, contrast, and luminance of
the debris items as they would appear to the turtle. We also
incorporated measures of texture and translucency to determine which of
the two hypotheses is more plausible as a driver of selectivity in green
sea turtles.
Results
Turtles preferred more flexible and translucent items to what was
available in the environment, lending support to the hypothesis that
they prefer debris that resembles prey, particularly jellyfish. They
also ate fewer blue items, suggesting that such items may be less
conspicuous against the background of open water where they forage.
Conclusions
Using visual modelling we determined the characteristics that drive
ingestion of marine debris by sea turtles, from the point of view of the
turtles themselves. This technique can be utilized to determine debris
preferences of other visual predators, and help to more effectively
focus management or remediation actions.
Keywords: Chelonia mydas; Chromatic space; Eretmochelys imbricata;
Marine debris; Vorobyev-Osorio model
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