Mather, Jennifer

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https://opus.uleth.ca/handle/10133/4538

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Browsing Mather, Jennifer by Subject "Diet"

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    Geographic variability of Octopus insularis diet: from oceanic island to continental populations
    (Inter Research, 2016) Leite, Tatiana S.; Batista, Allan T.; Lima, Francoise D.; Barbosa, Jaciana C.; Mather, Jennifer
    A predator’s choice of prey can be affected by many factors. We evaluated various influences on population dietary composition, individual specialization and size of prey in Octopus insularis populations from 2 continental and 4 insular locations. We expected that habitat diversity would lead to diet heterogeneity. Furthermore, in keeping with MacArthur & Wilson’s (1967) theory of island biogeography, we expected that diet diversity would be lower around islands than on the coast of the mainland. Both predictions were confirmed when prey remains from octopus middens were examined. The 2 continental areas exhibited a richer habitat diversity and a wider variety of prey. Niche widths in the continental areas were 2.42 and 2.03, with the lowest niche widths exhibited by the population from the most distant oceanic islands (1.30, 0.85). We found variation in the proportion of specialist relative to generalist individuals across areas based on the proportional similarity index. The correlation between habitat diversity and niche width (R2 = 0.84) was highly significant, as was distance from the continental shelf and niche width (R2 = 0.89). This study reaffirms the central position of octopuses in the nearshore benthic ecosystem, and supports MacArthur & Wilson’s (1967) prediction of a lower diversity of species on islands—which applies not only to the species themselves, but also indirectly for the diet of their predators.
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    Octopus vulgaris in the Caribbean is a specializing generalist
    (Inter Research, 2008) Anderson, Roland C.; Wood, James B.; Mather, Jennifer A.
    The diet of Octopus vulgaris was determined from the remains of 649 prey items gathered from the middens of 38 dens in a small area off the Caribbean island of Bonaire. Remains of 35 species of gastropod (19% of the total), 19 bivalves (51%) and 21 crustaceans (30%) were identified and examined for mode of entry into hard-shelled prey. Although 60% of the gastropods were drilled, neither the size/weight ratio nor the presence of an operculum determined whether drilling occurred. There were strong differences in prey preference among individual octopuses, and the Cardona niche breadth index (B’) of the midden items was 0.08, indicative of specialization. Examples include the exclusive preference for Pinna carnea by one den occupant. This study, by focusing on assessment of preference at specific den locations, is the first to show that while the population had a wide choice of prey items, the individual choices were much narrower, indicating that octopuses were specializing generalists.