Rocky subtidal and intertidal communities

Heather Hunt Lab Research

My lab has been carrying out research on the patterns and processes underlying biodiversity of hard-bottom marine invertebrates. We have collaborated with Rémy Rochette also at UNB Saint John to test the use of settlement cages (collectors) as a tool for monitoring biodiversity of benthic marine invertebrates and small benthic fishes in rocky subtidal habitats. Collaboration with researchers at a number of US and Canadian institutions who have also deployed collectors is enabling the examination of patterns over large spatial scales. We are also using the collectors to quantify changes in communities colonizing cobble-filled collectors, such as the recent detection of cunner in the Quoddy region of the Bay of Fundy, and to determine the relationship to changes in ocean temperature. We will also be employing the collectors to examine potential impacts of aquaculture on subtidal diversity.

I recently collaborated in an NSERC strategic project with Ladd Johnson (Université Laval) on the balance between urchin consumption and kelp production in the St. Lawrence maritime estuary and northern Gulf of Saint Lawrence in which my lab focused on urchin recruitment. I am currently collaborating with Nova Mieszkowska (Marine Biological Association of the UK) and Nessa O’Connor (Queen’s University Belfast) to examine southern species of topshell snails whose distributions in the rocky intertidal zone are shifting northwards in the UK due to climate change. I am using mesocosm experiments to examine the effects of winter extreme temperatures on topshells and the interactions between topshells and other grazing species.    

Sediment communities

Research in my lab has demonstrated that events that occur shortly after the settlement of larvae can be crucial, and that both mortality and dispersal affect recruitment of juveniles. On mudflats, graduate students in my lab have been studying patterns of abundance and distribution, dispersal, and mortality of the soft shell clam. Recently, we have examined the effect of pH and carbonate saturation on recruitment of soft shell clams. Ocean pH is decreasing and carbonate saturation is decreasing due to increased CO2 in the ocean, causing concerns for organisms like clams which construct their shells out of calcium carbonate. However, organisms that live within the sediment are exposed to very low and variable present-day pH and carbonate saturation values. Our research has shown that sediment acidification decreases burrowing and increases dispersal of juvenile clams.  We are planning new research to examine the relative effects of sediment acidification and water column acidification and the effects of variability in pH over time.