Hello darkness: red algae and patch dynamics on temperate rocky reefs

A brown alga (Desmarestia ligulata) holds its own in a patch of mixed red algae. Carmel Bay, California. PC: Patrick Webster

Rarely, if ever, are science projects carried out by one individual.  This is especially true for subtidal projects; it takes a lot of effort and energy to do work on and under the water. And, most importantly, diving is a buddy activity! 

With that said, I'm excited to share progress on a paper I am co-writing with the one and only Tristin McHugh, a formal manuscript from her master's dissertation at San Diego State University! That's right, we're coming back at you with an in depth look at out favorite marine organisms: macroalgae! 

Understanding patch dynamics is tricky; both biological and physical factors synergistically affect community composition and structure. For this study we were interested in how available light, and associated algal physiology, might drive algal abundance on rocky reefs. 

But rather than make you read pages and pages (yet), feel free to check out this talk I submitted to the Phycological Society of America's annual meeting last summer (July 2021).  For reference, our abstract is posted underneath. 

​Stay tuned for more updates as we continue to write up this paper, and let this PIG fly! 

​Phycyeah!

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Abstract submitted to PSA:

This study simulated physical disturbances of varying frequency and magnitude in two geographically distinct regions in California (Monterey, San Diego) and assessed the subtidal community’s response via benthic presence and photosynthetic capabilities. We sought to understand how a kelp forest may respond to the physical removal of brown algae canopy and sub-canopy layers, and what patterns of succession may take place. From pre and post-manipulation surveys, we saw a significant increase in red algal biomass within removal plots (i.e. simulated canopy removal), but did not see differences in red algal biomass or community assemblages across treatments. Rather, simple patchiness in red algae communities accounted for most of the variation observed in both locations, suggesting that community organization likely results from individual species’ life history characteristics, their ecologies, and stochastic processes. We then sought to understand the responses of red algae to these disturbances, and to subsequently understand their photosynthetic-capabilities, which can be thought of as a proxy for ecological success, to better understand if their responses were due to light adaptations from competitive release. In comparing photosynthetic properties (alpha and pmax), we found that sites, seasons, and the interaction between treatment and season were major drives of red algal photosynthetic capability. However, our results suggest that light adaptations in red algae do not reinforce patch dynamics in temperate reef communities.