Strong consequences of diet choice in a talitrid amphipod consuming seagrass and algal wrack
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Deposits of detached macrophytes, known as wrack, are a common feature on shore lines and can represent an important subsidy of organic material from subtidal systems to low productivity intertidal and terrestrial systems. On beaches, these support high densities of consumers that have an important role in wrack decomposition. The feeding behavior of wrack consumers is poorly known relative to the marine herbivores that consume marine macrophytes in situ. To understand how feeding behavior relates to the quality of wrack for an abundant wrack consumer, the talitrid amphipod Notorchestia sp., we test for habitat preferences, differences in feeding rates, and survival among four species of macroalgae and seagrasses in an estuary in New South Wales, Australia. Notorchestia displayed strong preferences for Sargassum sp. and Zostera capricorni as habitat, but consumed only Sargassum in feeding experiments, and only this alga supported high survival in a longer term performance assay. The differences in food quality, as measured by survival over 30 days, did not translate to differences in the abundance of amphipods colonizing each food resource in the field. Our results suggest that feeding by Notorchestia will result in the rapid loss of Sargassum in the wrack, and that other consumers or microbial degradation may be more important in the decomposition of seagrass.
KeywordsAmphipods Wrack Algae Seagrass Survival
We thank Jessica Spies for assistance with field work, Jim Lowry for the amphipod identification, and two anonymous reviewers for comments that improved this manuscript. The research was supported by an Australian Research Council grant (DP055632) to AGBP.
- Colombini, I. & L. Chelazzi, 2003. Influence of marine allochthonous input on sandy beach communities. Oceanography and Marine Biology: An Annual Review 41: 115–159.Google Scholar
- Griffiths, C. L., J. M. E. Stenton-Dozey & K. Koop, 1983. Kelp wrack and the flow of energy through a sandy beach ecosystem. Dr. W, Junk Publishers, The Hague.Google Scholar
- Jędrzejczak, M. F., 2002. Stranded Zostera marina L. vs wrack fauna community interactions on a Baltic sandy beach (Hel, Poland): a short-term pilot study. Part II. Driftline effects of succession changes and colonisation of beach fauna. Oceanologia 44(3): 367–387.Google Scholar
- Olabarria, C., M. Incerra, J. Garrido, I. F. Rodil & F. Rossi, 2009. Intraspecific diet shift in Talitrus saltator inhabiting exposed sandy beaches. Estuarine, Coastal and Shelf Science 84: 282–288.Google Scholar
- Paul, V. J., E. Cruz-Rivera & R. W. Thacker, 2001. Chemical mediation of macroalgal-herbivore interactions: ecological and evolutionary perspectives. In McClintock, J. B. & B. J. Baker (eds), Marine Chemical Ecology. CRC Press, Boca Raton: 227–265.Google Scholar
- Poore, A. G. & P. D. Steinberg, 1999. Preference-performance relationships and effects of host plant choice in an herbivorous marine amphipod. Ecological Monographs 69(4): 443–464.Google Scholar
- Poore, A. G. B., A. H. Campbell, R. A. Coleman, G. J. Edgar, V. Jormalainen, P. L. Reynolds, E. E. Sotka, J. J. Stachowicz, R. B. Taylor, M. A. Vanderklift & J. E. Duffy, 2012. Global patterns in the impact of marine herbivores on benthic primary producers. Ecology Letters 15: 912–922.Google Scholar
- Stenton-Dozey, J. M. E. & C. L. Griffiths, 1983. The fauna associated with kelp stranded on a sandy beach. In McLachlan, A. & T. Erasmus (eds), Sandy Beaches as Ecosystems. Dr. W. Junk Publishers, The Hague: 557–567.Google Scholar