CHAPTER FOUR Ecological Interactions and the Distribution, Abundance, and Diversity of Sponges Janie Wulff1 Contents 1. Introduction 274 1.1. Evaluating distribution, abundance, and diversity of sponges 277 2. Influences of Abiotic Factors and Ecological Interactions on Sponges in Various Habitats 281 2.1. Subtidal rocky substrata—walls, plateaus, canyons 282 2.2. Subtidal rocky substrata—cobbles and caves 290 2.3. Coral reefs 292 2.4. Coral reefs—cryptic spaces 315 2.5. Mangroves 317 2.6. Sediment dominated habitats, including seagrass meadows 322 2.7. Intertidal shores 325 2.8. Antarctic hard bottoms 327 3. Conclusions 329 Acknowledgements 331 References 331 Abstract Although abiotic factors may be important first-order filters dictating which sponge species can thrive at a particular site, ecological interactions can play substantial roles influencing distribution and abundance, and thus diversity. Ecological interactions can modify the influences of abiotic factors both by further constraining distribution and abundance due to competitive or preda- tory interactions and by expanding habitat distribution or abundance due to beneficial interactions that ameliorate otherwise limiting circumstances. It is likely that the importance of ecological interactions has been greatly Department of Biological Science, Florida State University, Tallahassee, FL, USA 1Corresponding author: Email:
[email protected] Advances in Marine Biology, Volume 61 # 2012 Elsevier Ltd ISSN 0065-2881, DOI: 10.1016/B978-0-12-387787-1.00003-9 All rights reserved. 273 274 Janie Wulff underestimated because they tend to only be revealed by experiments and time-series observations in the field. Experiments have revealed opportunistic predation to be a primary enfor- cer of sponge distribution boundaries that coincide with habitat boundaries in several systems.