Research | Rémy Rochette Lab | Research | Faculty of SASE | UNB

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Patterns, mechanisms and constraints of adaptive phenotypic variation

The main goal of this research is to develop and test hypotheses explaining patterns, mechanisms and constraints modulating phenotypic evolution in marine invertebrates. My students and I use as a model system for much of this research a predator-prey relationship from the Northwest Atlantic coast, involving the European green crab Carcinus maenas (an exotic species) and the intertidal snail Littorina obtusata.

Our research approach involves a combination of large-scale geographic surveys to elucidate patterns of phenotypic variation in nature, and controlled experiments in the field and lab to elucidate the evolutionary significance of this variation. We conduct mensurative and manipulative experiments to address hypotheses pertaining to the i) adaptive value, ii) micro-evolutionary mechanisms (e.g., genetic adaptation, phenotypic plasticity, evolution of reaction norms), iii) developmental mechanisms (e.g., role of environmental cues), iv) micro-evolutionary constraints (e.g., gene flow) and v) developmental constraints (e.g., correlated characters) underlying natural patterns of phenotypic variation among populations of predators and their prey.

One hypothesis of current interest is that C. maenas and L. obtusata are engaged in a co-evolutionary arms race on wave-sheltered rocky shores of the northwest Atlantic.

Ecological interaction between adult green crab and young lobster

The European green crab, Carcinus maenas, is a highly successful global invader with the potential to interact with native crustacean populations, including those of the American lobster Homarus americanus, through competition and predation. Our goal is to investigate the nature and outcome of these interactions, including how they may vary geographically and during the organisms' ontogeny.

We address these objectives using a combination of fieldwork based on SCUBA diving, laboratory-staged short-term (hours) and longer term (months) encounters between individuals of these two species, and stomach content analyses using genetic barcoding technology. The genetic work is done in collaboration with France Dufresne at UQAR.

Marine biodiversity in rocky subtidal habitats: spatio-temporal dynamics, controlling factors and conservation

Coastal marine habitats and organisms are being compromised at an unprecedented rate by human activities and most effects are going unnoticed because insufficient resources are invested in describing what lives in our oceans. In this project, we propose to develop a tool and monitoring program to assist the management of regions in the Bay of Fundy that have recently been identified as Ecologically and Biologically Significant Areas (EBSAs) by the Department of Fisheries and Oceans (DFO).

This project tests the use of settlement cages (collectors) as a tool for monitoring biodiversity of benthic marine invertebrates and small benthic fishes in rocky subtidal habitats. The collectors offer a method for comparing biodiversity among sites and regions in a standardized way with low impact to the environment. They can also be used in areas that are difficult for divers to sample, for example due to excessive depth or currents.

Identification of species is based on morphological characteristics and DNA barcoding. This research is supported by a NSERC Strategic Projectgrant, and is a collaboration with Dr. Heather Hunt (UNB Saint John), Dr. France Dufresne (UQAR), Dr. Gerhard Pohle (Atlantic Reference Centre, Huntsman Marine Science Centre), the Canadian Department of Fisheries and Oceans and the Fishermen and Scientists Research Society.

Age determination in Crustaceans

Decapod crustaceans, such as American lobster, snow crab and northern shrimp, are an important component of Canadian society and economy. Sound management of these fisheries is therefore crucial. One of the more important parameters fisheries scientists rely upon to assess and manage stocks is the age of individuals, which is used to calculate growth and mortality rates, recruitment and productivity.

Whereas the age of wild animals can often be determined by examining calcified structures (e.g., bones, scales, otoliths, shells), this method has not been used in decapod crustaceans, due to the loss of integumental structures at each moult. The research we have recently embarked on will investigate the potential of a promising new method for revealing absolute age of individual decapod crustaceans.

This research is supported by a NSERC Strategic Project grant, and is a collaboration with Dr. Raouf Kilada (UNB Saint John), Dr. Bernard Sainte-Marie (Institut Maurice Lamontagne), Dr. Steve Campana (Bedford Institute of Oceanography), the Canadian Department of Fisheries and Oceans, the Fishermen and Scientists Research Society and the Canadian Association for Prawn Producers.

Metapopulation dynamics, management areas and biological units of American lobster Homarus americanus in eastern Canada

The American lobster Homarus americanus supports the most important fishery in Canada, in terms of landed resource value. The species has thus been extensively studied over the past several decades, and we now have considerable understanding of its biology and fisheries ecology. However, the mechanisms underlying temporal and spatial variation in lobster demography remain largely elusive, as evidenced by our inability to explain the marked changes in landings different regions experienced over the past hundred years.

One major impediment is our limited understanding of the species’ meta-population dynamics, and in particular source-sink dynamics and connectivity among different “local populations” via the movement of adults on the benthos and larvae in the plankton. It is this question of “biological unit”, or “lobster production area”, that this project proposes to study, a question that was identified as one of the most significant impediments to the management of the resource by the 2007 FRCC "Report on a sustainability framework for Atlantic lobster".

This project was the object of a recent proposal in the context of a NSERC Strategic Network on Capture Fisheries. It represents a large collaboration between academia, government, and industry, including 14 biologists and scientists from the Department of Fisheries and Oceans, UNB, UPEI, UMoncton, UQAR and ULaval, as well as industrial partners in Québec, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland, in coordination with the Canadian Council of Professional Fish Harvesters.