MEPS 388:1-11 (2009)  -  doi:10.3354/meps08131

Community structure and productivity of subtidal turf and foliose algal assemblages

Robert J. Miller1,*, Daniel C. Reed1, Mark A. Brzezinski1,2

1Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106, USA
2Marine Science Institute, University of California, Santa Barbara, California 93106, USA

ABSTRACT: Foliose and turf-forming macroalgae form morphologically distinct assemblages on shallow reefs worldwide and frequently coexist in a patch mosaic. The relative contributions of these algal assemblages to reef productivity and the processes that maintain them, however, have rarely been studied. We found high (80%) species overlap between turfs and foliose macroalgae at Naples Reef off southern California, with differences between the 2 assemblages lying in species dominance and morphology rather than composition. Turfs were dominated by a small finely-branched red alga, Pterosiphonia dendroidea, while larger blade-forming red algae, particularly Chondracanthus corymbiferus and Rhodymenia californica, dominated foliose assemblages. Foliose dominants were common in turfs, but were small. Area-specific rates of net primary production of foliose assemblages were ~3× higher than those of turfs, while rates of carbon-specific production and turnover times of turfs were ~3× higher than those of foliose assemblages. These findings suggest that factors other than the growth potential of each assemblage determined their relative biomass. Turfs were net heterotrophic, with net community production <0, due to greater abundance of macrofauna, compared to foliose assemblages. The abundance of macrofaunal invertebrates was uncorrelated with productivity within or among assemblages, suggesting that turfs are structurally better habitats for macrofauna. Our results suggest that maintenance of turf assemblages on Naples Reef is not the result of competitive exclusion of foliose algae by turf species; turf morphology appears to be maintained through the stunting of foliose forms by fishes that crop turfs while foraging for invertebrate prey.

KEY WORDS: Primary production · California · Macrofauna · Net primary production · NPP · Turf algae

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Cite this article as: Miller RJ, Reed DC, Brzezinski MA (2009) Community structure and productivity of subtidal turf and foliose algal assemblages. Mar Ecol Prog Ser 388:1-11

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