Food and habitat partitioning in grazing snails (<Emphasis Type="Italic">Turbo smaragdus</Emphasis>), Northern New Zealand |
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| Authors: | Andrea C Alfaro Severine E Dewas François Thomas |
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| Institution: | 1.Division of Applied Sciences, Faculty of Health and Environmental Sciences,Auckland University of Technology,Auckland,New Zealand |
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| Abstract: | Gut content analyses and fatty acid profiles were used to identity food consumption and assimilation in a dominant grazing
snail (Turbo smaragdus) in rocky shore and estuarine habitats, at Waiwera Estuary, northern New Zealand. Gut contents of freshly collected individuals
indicated that snails utilize a wide range of food sources within their habitats, including microalgae and foliose-corticated
macrophytes (rocky intertidal), and mangrove tissue and filamentous algae (mangrove stand). Laboratory feeding experiments
revealed thatT. smaragdus prefers microalgae and possibly filamentous epiphytes, regardless of snail size or habitat of origination. The fatty acid
profiles of snails fed different diets (brown algae Hormosira banksii], diatoms, mangrove pneumatophores, and filamentous green algae Chaetomorpha sp.]) confirmed the assimilation of the given foods, except for the mangrove treatment, which resulted in a low, long chain,
fatty acid (LCFA) signature. Incongruities between the gut content analyses (high number of mangrove particles) and fatty
acid profiles (low LCFA signature) of field and laboratory snails exposed to a mangrove diet suggest that snails target microalgal
and filamentous epiphyte food sources on the pneumatophores and inadvertently ingest mangrove particles. Snails within all
food treatments, except diatoms, had a relatively strong bacterial signature (18∶1n–7, Σ15+Σ17). Bacteria may have readily
accumulated in the experimental tanks and been selected by snails as an alternative food source. In the field, snails and
other grazers may ingest detritus and biofilms to access dense populations of bacteria. This research highlights the need
for a comprehensive and multianalytical approach to elucidate the role of grazers in algal-plant dominated ecosystems. |
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