Sandrine Laurand

Project

Characterization of the structure and dynamics of Dublin bay food web and the effect of anthropogenic inputs

Coastal ecosystems are subjected to a considerable number of anthropogenic pressures, particularly when located near important urban centres such as in Dublin Bay. Some of these constraints, such as high particulate organic matter and nutrient inputs from the catchment, can alter the normal functioning of the ecosystem. Excess of nutrients induce eutrophication problems with the risk of heavy algal developments (micro- and macrophytes), which may disturb other populations, and can cause mass mortality of the fauna in extreme cases. High loadings of particulate matter can engender population changes, modifying the balance and the structure of the trophic web, which can have repercussions up to the top predators.  
In Dublin Bay, previous work mainly based on network analysis suggested that the allochtonous inputs of organic matter and nutrients from the watershed (essentially from the river and sewage effluent) were among the main drivers of the system. For management purposes, it is of prime importance to trace the fate of these inputs through the ecosystem, to fully understand how they interact with the different components of the food web, and finally to comprehend the dynamics of these interactions and of the matter fluxes with time and space.

This PhD project was therefore initiated to characterise the architecture and the spatio-temporal dynamics of the food web in Dublin bay and investigate how it relates to the anthropogenic inputs of organic matter. Stable isotopes analysis (d13C, d15N) was notably applied to study, through a seasonal survey, different environments of the Dublin Bay ecosystem (estuary, subtidal area and intertidal flats and lagoons). These included two sites which encounter serious eutrophication problems during summer, with a localised heavy phytoplanktonic bloom and a heavy green algae development (green tide).
Results obtained will notably be of interest in term of management potential. It will specifically deepen our understanding of the functioning of this ecosystem, provide data to be incorporated into more elaborate models of the bay and also shed light on the impact of algal blooms on trophic webs.

Research Interests

● Large interest in aquatic ecology and marine ecosystem management and conservation
● Impact of natural and anthropogenic sources of environmental change on marine ecosystems: direct and indirect effects, response of aquatic communities
● Food web studies in marine ecosystems
● Application of stable isotopes techniques to ecology studies

Publications

Laurand, S.; Riera, P. (2006) Trophic ecology of the supralittoral rocky shore (Roscoff, France): A dual stable isotope (d13C, d15N) and experimental approach. Journal of Sea Research 56: 27-36

Postal address

Email                        

laurands@tcd.ie