Prey taxonomy rather than size determines salp diets

Ayelet Dadon-Pilosof*, Fabien Lombard, Amatzia Genin, Kelly R. Sutherland, Gitai Yahel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Salps are gelatinous planktonic suspension feeders that filter large volumes of water in the food-dilute open ocean. Their life cycle allows periodic exponential growth and population blooms. Dense swarms of salps have a high grazing impact that can deplete the photic zone of phytoplankton and export huge quantities of organic matter to the deep sea. Previous studies described their feeding manner as mostly nonselective, with larger particles retained at higher efficiencies than small particles. To examine salp diets, we used direct in situ sampling (InEx method) of undisturbed solitary Salpa maxima. Aggregates (“chains”) of Salpa fusiformis and Thalia democratica were studied using in situ incubations. Our findings suggest that in situ feeding rates are higher than previously reported and that cell removal is size independent with ∼ 1 μm picoeukaryotes preferentially removed over both larger eukaryotes and smaller bacteria. The prey : predator size ratios we measured (1 : 104–1 : 105) are an order of magnitude smaller than previously reported values and to the best of our knowledge, are the smallest values reported so far for any planktonic suspension feeders. Despite differences among the three species studied, they had similar prey preferences with no correlation between salp body length and prey size. Our findings shed new light on prey : predator relationships in planktonic systems—in particular, that factors other than size influence filtration efficiency—and suggest that in situ techniques should be devised and applied for the study of suspension feeding in the ocean.

Original languageEnglish
Pages (from-to)1996-2010
Number of pages15
JournalLimnology and Oceanography
Volume64
Issue number5
DOIs
StatePublished - 1 Sep 2019

Bibliographical note

Publisher Copyright:
© 2019 The Authors. Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography.

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