Thermal stress decreases developmental stability in marine mussels.

Faced with rising environmental temperatures, there is growing evidence that species are exhibiting shifts in ecological distribution, physiological performance, behavioral strategy and developmental rate. However, the efficacy of these varied responses is often rooted in an organism’s ability to fulfill precise developmental patterns. Links between environmental conditions and the precision with which organisms are able to fulfill their developmentally programmed phenotype remains an important, and largely unanswered question. Results from our lab and field experiments suggest that developmental instability, as assessed by the fluctuating asymmetry of right versus left valves in intertidal mussel shells, increases under elevated aerial temperatures. These results imply that the precision of developmental processes can be perturbed by environmental conditions and raise developmental instability as a potential impact of future climate change alongside shifts in physiology, behavior and biogeographic distribution.

Future work will explore the functional consequences of shell asymmetry in marine mussels. The degree to which developmental instability may or may not affect the ecology of mussels in the field or in aquaculture remains an interesting and unanswered question.

Ecological consequences of changing patterns of temperature variation in bivalves

Ongoing changes in climatic conditions are predicted to increase the frequency of extreme environmental events (e.g., storms, heat waves). The ecological consequences of such environmental variation can be as important as simple shifts in mean temperature or flow. Factors such as temperature and flow fluctuate at different frequencies, and the distribution of those frequencies can be described by power spectrum models. This variation can be broadly categorized into different environmental noise colors. For instance, “white noise” has equal power at all frequency scales, whereas “red noise” is dominated by long-term, low frequency fluctuations. Environmental variation in marine ecosystems are often characterized as “red noise”, and changes to the shape of the red noise variance spectra are known to influence population abundance in marine intertidal ecosystems. Less is understood, however, about the effect that changes in noise color might have on physiological and behavioral processes that underlie many ecological dynamics. This type of mechanistic understanding is required to generate accurate predictions about how species will respond to novel environmental conditions that do not exist today.

With the help of undergraduate research assistants, I am currently running experiments comparing the effects of stable versus fluctuating temperatures on mussel physiology, behavior and growth.

Gene expression work

Sunrise at Rhode Island field site.

Phenotypic variation - plasticity, canalization, instability
Fig. 1. Phenotpic variation. Plasticity, canalization and instability
temperature variation
Fig. 2. Temperature variation in barnacle temperatures.