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Design and Use of an Apparatus for Quantifying Bivalve Suspension Feeding at Sea
Published on: September 5, 2018
Refuge function of marine algae complicates selection in an intertidal snail
Petri Kemppainen1, Solveig van Nes, Christofer Ceder
1Department of Marine Ecology, Tjärnö Marine Biological Laboratory, Göteborg University, 452 96, Sweden.
Oecologia
|February 16, 2005
Summary
Marine gastropod Littorina fabalis size varies with habitat. Larger sizes in wave-exposed areas may be an adaptation to crab predation, while smaller sizes are favored in sheltered areas, demonstrating complex trait selection.
Area of Science:
- Marine ecology
- Evolutionary biology
- Behavioral ecology
Background:
- Marine gastropods with restricted gene flow often exhibit habitat-specific trait shifts.
- Typically, gastropod size decreases in wave-exposed areas to prevent dislodgement and increases in sheltered areas to deter crab predation.
- Littorina fabalis presents an atypical pattern, with larger snails in moderately exposed shores and smaller snails in sheltered shores.
Purpose of the Study:
- To investigate the factors influencing the contrasting shell sizes of Littorina fabalis in different habitats.
- To test the hypothesis that increased size in moderately exposed habitats is a response to crab predation.
- To understand the interplay of predation, dislodgement, and habitat structure in shaping snail morphology.
Main Methods:
- Comparative observations of snail size in different habitats across varying wave exposure and crab presence.
- Experimental tethering of snails to assess survival rates and predator avoidance in relation to substrate and wave action.
- Analysis of snail mortality factors, including crab predation and dislodgement, in both sheltered and exposed environments.
Main Results:
- In the absence of crabs, Littorina fabalis remains small in both sheltered and exposed habitats, suggesting an optimal size below 8 mm.
- Crab predation significantly impacts snail survival in both sheltered and moderately exposed habitats in crab-rich areas.
- Algal cover acts as a crucial refuge against crab predation in sheltered habitats, favoring smaller snail sizes potentially due to life-history benefits.
- In moderately exposed habitats, larger snail size is favored, likely as a strategy to withstand dislodgement while still benefiting from algal refuges.
Conclusions:
- Littorina fabalis exhibits complex adaptive trait selection driven by a combination of factors: life-history optimization, crab predation, wave-induced dislodgement, and the protective role of algal refuges.
- The study highlights how different ecological pressures interact to determine optimal phenotypes in marine gastropods.
- This research provides a nuanced example of trait evolution in response to multiple, interacting environmental variables.
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