Overwintering tropical herbivores accelerate detritus production on temperate reefs

Salvador Zarco-Perello, Tim J Langlois, Thomas Holmes, Mathew A Vanderklift, Thomas Wernberg

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The tropicalization of temperate marine ecosystems can lead to increased herbivory rates, reducing the standing stock of seaweeds and potentially causing increases in detritus production. However, long-term studies analysing these processes associated with the persistence of tropical herbivores in temperate reefs are lacking. We assessed the seasonal variation in abundances, macrophyte consumption, feeding modes and defecation rates of the range-extending tropical rabbitfish Siganus fuscescens and the temperate silver drummer Kyphosus sydneyanus and herring cale Olisthops cyanomelas on tropicalized reefs of Western Australia. Rabbitfish overwintered in temperate reefs, consumed more kelp and other macrophytes in all feeding modes, and defecated more during both summer and winter than the temperate herbivores. Herbivory and defecation increased with rabbitfish abundance, but this was dependent on temperature, with higher rates attained by big schools during summer and lower rates in winter. Still, rabbitfish surpassed temperate herbivores, leading to a fivefold acceleration in the transformation of macrophyte standing stock to detritus, a function usually attributed to sea urchins in kelp forests. Our results suggest that further warming and tropicalization will not only increase primary consumption and affect the habitat structure of temperate reefs but also increase detritus production, with the potential to modify energy pathways.
TidsskriftProceedings of the Royal Society B: Biological Sciences
Udgave nummer1915
StatusUdgivet - 20 nov. 2019

Bibliografisk note

This article has been found as a ’Free Version’ from the Publisher on April 21, 2020. When access to the article closes, please notify [email protected]


  • climate change
  • detritus
  • herbivory
  • kelp
  • seasonality
  • tropicalization

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