Published July 11, 2022 | Version v1
Dataset Open

Shield wall: Kelps are the last stand against corals in tropicalised reefs

  • 1. Federal Fluminense University*
  • 2. University of Western Australia
  • 3. Instituto de Pesquisas Jardim Botânico do Rio de Janeiro

Description

Communities inhabiting biogeographic transition zones are shifting in composition as a result of progressive warming and heatwaves. In the marine environment, corals are expanding onto higher latitude reefs historically dominated by temperate kelp forests, initiating a shift towards warm-affinity coral dominated states. Although these coral expansions are a global phenomenon, the mechanisms that are underpinning the expansion process remain poorly understood, which limits the projections of the rate and extent of ecosystem reconfiguration. Here, we investigated the interaction between the kelp Ecklonia radiata and the high latitude scleractinian coral Plesiastrea versipora in several of Western Australia's temperate reefs, where coral colony abundance has increased by 50% in recent years. Combining field surveys with field and laboratory experiments, we test the importance of physical (abrasion and light reduction) and chemical (allelopathic effects) effects of kelp canopies on coral tissue cover, photosynthetic parameters, and calcification rates. In the field, kelp cover had a negative effect on coral density that was overwhelming in comparison to other dominant macroalgal taxa. Abrasion by kelp whiplash was the predominant mechanism by which kelp exerted a negative effect on P. versipora fitness, scraping up to 80% of live coenosarc from experimental colonies. In contrast, canopies had no effects on P. versipora photochemical efficiency and laboratory incubations showed that there were no allelochemical effects from kelp on P. versipora. We conclude that E. radiata inhibits P. versipora establishment and development through abrasion, and the survey data confirmed that recent climate-driven kelp loss released corals from this effect, facilitating their expansion on high-latitude reefs in Western Australia. This shows how competitive interactions actively shield against species expansion in biogeographic transition zones and suggests a continued decline of kelp canopies will increase the permeability of temperate reefs to warm affinity species such as scleractinian corals.

Notes

Funding provided by: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100002322
Award Number:

Funding provided by: Australian Research Council
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100000923
Award Number: DP170100023

Funding provided by: Australian Research Council
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100000923
Award Number: DP190100058

Files

README_RIBEIROetal.2022_dryad.txt

Files (107.1 kB)

Name Size Download all
md5:c915813e517bc9a61f132c0401edea63
14.7 kB Download
md5:24191031f48e2b541d65fbdfa4575c05
12.6 kB Download
md5:f9ebd342ba9fe59eccdeb7e1a846f2a2
19.0 kB Download
md5:f1c27d013a7bd47d7dfd596f6a6cfb4e
9.7 kB Download
md5:acae2df483cd2675bed126cc400bc26c
13.3 kB Download
md5:f455d7ae949ec20b23e68fdcc5077cee
11.6 kB Download
md5:4160c563275107d2a25c11c1ff752c57
10.2 kB Download
md5:c320773e8e72a8e87c72526192012941
16.0 kB Preview Download