ECOLOGY/EVOLUTION

Nutrient Recycling

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Science  10 Oct 2003:
Vol. 302, Issue 5643, pp. 199
DOI: 10.1126/science.302.5643.199c

Transport of nutrients from terrestrial to aquatic habitats is mostly a physical process. Transport in the opposite direction has a significant biological component, for instance in the form of guano from seabirds or the carcasses of salmon that have returned from the sea to spawn. Farina et al. show that a marine mammal, the Galapagos sea lion (Zalophus wollebackei), is an effective vector of nutrients from the sea to the land. Nitrate and ammonia concentrations in soils from low-elevation shoreline sites favored by sea lions were higher than in other sites, in some cases by an order of magnitude. The nitrogen and carbon isotopic ratios in plants from these sites were consistent with a marine bias in the origin of these nutrients. Because seabird and sea lion colonies are completely separate, and breeding colonies of the sea lions are present year-round, the authors could rule out an influence of seabirds on their results. — AMS

J. Anim. Ecol. 72, 873 (2003).

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