Consumer responses to habitat depletion: food-refuge interactions in intertidal periwinkles


The School of Biological Sciences at Southampton University is hosting a NERC Grant (PI Dr Patrick Doncaster) for a 3-year collaborative project with Professor Steve Hawkins, Director of the Marine Biological Association, and Dr Richard Thompson, Reader at Plymouth University. Splash-zone periwinkles are being used as a model organism for testing recent theories about the responses of populations to habitat degradation or enrichment. These small snails occupy any depressions and crevices of upper shore rocks, from where they explore just a few centimetres in a 'foraging halo' to scrape off the encrusting black algae. Such sedentary habits make them particularly well suited to experimental manipulation of refuge sites and food resources, because existing crevices can be filled in or new ones drilled into the rock, and resources can be brushed off or watered with supplementary nutrients. Outcomes from field experiments will inform our understanding of the dynamic processes driving rarity and extinction threat in the face of habitat loss, which is currently the most prevalent cause of biodiversity loss across taxa and ecosystems.


Click here for an overview of the results of the project



Fig. 1. Foraging halo for the above-tide periwinkle Melaraphe neritoides. Foraging around the refuge pit has scraped the rock clean of the dark microbial film from the substratum (in this case a concrete sea wall) within a radius of 20-40 mm around the periwinkles' refuge pit. Similar haloes occur around pits and crevices occupied by Littorina saxatilis. The microbial film at upper shore levels is primarily cyanobacteria but with diatoms prevalent in the winter.



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