pubmed.ncbi.nlm.nih.gov

Giant kelp, Macrocystis pyrifera, increases faunal diversity through physical engineering - PubMed

  • ️Mon Jan 01 2018

Giant kelp, Macrocystis pyrifera, increases faunal diversity through physical engineering

Robert J Miller et al. Proc Biol Sci. 2018.

Abstract

Foundation species define the ecosystems they live in, but ecologists have often characterized dominant plants as foundational without supporting evidence. Giant kelp has long been considered a marine foundation species due to its complex structure and high productivity; however, there is little quantitative evidence to evaluate this. Here, we apply structural equation modelling to a 15-year time series of reef community data to evaluate how giant kelp affects the reef community. Although species richness was positively associated with giant kelp biomass, most direct paths did not involve giant kelp. Instead, the foundational qualities of giant kelp were driven mostly by indirect effects attributed to its dominant physical structure and associated engineering influence on the ecosystem, rather than by its use as food by invertebrates and fishes. Giant kelp structure has indirect effects because it shades out understorey algae that compete with sessile invertebrates. When released from competition, sessile species in turn increase the diversity of mobile predators. Sea urchin grazing effects could have been misinterpreted as kelp effects, because sea urchins can overgraze giant kelp, understorey algae and sessile invertebrates alike. Our results confirm the high diversity and biomass associated with kelp forests, but highlight how species interactions and habitat attributes can be misconstrued as direct consequences of a foundation species like giant kelp.

Keywords: competition; ecosystem engineering; facilitation; foundation species; kelp forest; subtidal.

© 2018 The Author(s).

PubMed Disclaimer

Conflict of interest statement

We have no competing interests.

Figures

Figure 1.
Figure 1.

Piecewise SEM model of the effect of giant kelp biomass and sea urchin biomass on biomass and diversity order 1 (see Material and methods) of four taxonomic functional groups, represented by the blue boxes: (1) understorey macroalgae, (2) sessile invertebrates, (3) mobile grazers and (4) mobile predators. Effects of substrate on the biomass of sessile groups are also shown. Arrows represent unidirectional relationships among variables. Blue arrows denote positive relationships, and orange arrows negative relationships. Arrows for non-significant paths (p ≥ 0.05) are not shown. The thicknesses of the significant paths reflect the magnitude of the standardized regression coefficients given alongside. R2-values inside boxes are conditional R2.

Similar articles

Cited by

References

    1. Darwin C. 1909. The voyage of the Beagle. New York, NY: PF Collier & Son.
    1. Jones CG, Lawton JH, Shachak M. 1997. Positive and negative effects of organisms as physical ecosystem engineers. Ecology 78, 1946–1957. (10.1890/0012-9658(1997)078%5B1946:PANEOO%5D2.0.CO;2) - DOI
    1. Baiser B, Whitaker N, Ellison A. 2013. Modeling foundation species in food webs. Ecosphere 4, art146 (10.1890/ES13-00265.1) - DOI
    1. Dayton PK. 1972. Toward an understanding of community resilience and the potential effects of enrichments to the benthos at McMurdo Sound, Antarctica. In Colloquium on conservation problems in Antarctica (ed. Parker B.), pp. 81–96 Lawrence, KS: Allen Press.
    1. Ellison A, et al. 2005. Loss of foundation species: consequences for the structure and dynamics of forested ecosystems. Front. Ecol. Environ. 3, 479–486. (10.1890/1540-9295(2005)003%5B0479:LOFSCF%5D2.0.CO;2) - DOI

Publication types

MeSH terms

LinkOut - more resources