Dr Patrick Martone1
1University Of British Columbia, Vancouver, Canada
One central paradigm of coralline algal ecology is that calcification reduces herbivory. Indeed, when herbivore abundance is high, calcified coralline algae generally dominate seaweed communities. For decades, ecologists have explained this observation by proposing that calcified thalli are more difficult to graze and less nutritious, given that a significant portion of coralline biomass is calcium carbonate. If true, then negative impacts on coralline calcification rates due to future climate stress may alter grazing patterns in unexpected ways. We revisited the ecological consequences of calcification in a series of targeted experiments. In urchin and isopod feeding trials, we found that serial decalcification of several coralline species had no significant effect on grazing rates: fully calcified thalli were eaten as much as fully decalcified thalli. In only one coralline-grazer interaction did we demonstrate an increase in herbivory after decalcification, suggesting that protection provided by calcification is not generalizable and may be interaction-specific. Using a bomb-calorimeter, we calculated the caloric value of several coralline species on a per-volume basis. We found that the caloric value of a “mouthful” of coralline algae is similar to – and sometimes greater than – that of kelp. While coralline thalli are predominantly calcium carbonate, kelp thalli are predominantly water, and the actual algal fraction of these two thallus types is quite similar. Given these flaws in our understanding of coralline ecology, other possible explanations for grazer deterrence are needed.
Presentation Slides – Patrick Martone
Biography:
Patrick Martone is a professor and marine phycologist in the Botany Department at the University of British Columbia (UBC). Research in his lab focuses on the biology and biodiversity of seaweeds: from cell wall chemistry and tissue development, through ecophysiology and evolution, to ecology and community structure. Patrick is passionate about teaching the wonders of seaweed, inspiring hundreds of students at UBC and the Bamfield Marine Sciences Centre. Patrick is the President of the Phycological Society of America.
