Patch size and density of canopy-forming kelp modify influences of ecosystem engineering on understorey algal and sessile invertebrate assemblages

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 632:59-79 (2019) - DOI: https://doi.org/10.3354/meps13155 Patch size and density of canopy-forming kelp modify influences of ecosystem engineering on understorey algal and sessile invertebrate assemblages Victor Shelamoff*, Cayne Layton, Masayuki Tatsumi, Matthew J. Cameron, Jeffrey T. Wright, Craig R. Johnson Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia *Corresponding author: victor.shelamoff@utas.edu.au ABSTRACT: Ecosystem engineers are important in shaping the composition of associated communities, including the abundance of species which exert additional influences on the ecosystem. Using an array of 28 artificial reefs supporting transplants of a dominant canopy-forming kelp (Ecklonia radiata) representing 7 patch sizes (0.12-7.68 m2) crossed with 4 kelp densities (0-16 ind. m-2), we determined how differences in the patch size and density of this ecosystem engineer influenced the associated understorey assemblages, including the abundance of turf algae, foliose algae and sessile invertebrates. We then determined how abiotic and biotic factors modified by E. radiata related to the abundance of these functional groups and E. radiata recruitment. Decreasing patch size and absence of kelp led to the proliferation of turfs, whilst foliose algae and invertebrates were dominant on larger reefs with kelp, where intermediate densities of kelp supported the highest abundance of foliose algae. We postulate that benthic light was the most important factor positively influencing turf cover, which in turn suppressed foliose algae. Adverse effects of light and sediment deposition best explained the cover of invertebrates. Contrary to expectation, understorey species had little effect on the density of E. radiata recruits, which instead was strongly correlated with the abundance of transplanted kelp on each reef. These results highlight the capacity of E. radiata to influence major functional groups within the sub-canopy via abiotic ecosystem engineering and through control of turfs and indicate that the negative effect of understorey algae on kelp recruitment may be context specific. KEY WORDS: Ecosystem engineer · Foliose algae · Kelp · Understorey · Recruitment · Sessile invertebrate · Turf algae · Ecklonia radiata Full text in pdf format PreviousNextCite this article as: Shelamoff V, Layton C, Tatsumi M, Cameron MJ, Wright JT, Johnson CR (2019) Patch size and density of canopy-forming kelp modify influences of ecosystem engineering on understorey algal and sessile invertebrate assemblages. Mar Ecol Prog Ser 632:59-79. https://doi.org/10.3354/meps13155 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 632. Online publication date: December 12, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.