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Ryan Shea


Ryan Shea heaves on a heavy kelp line from a raft at an IMTA site in the Bay of Fundy, Canada (photo: Thierry Chopin).

Honours Thesis: 2005

Thesis: Effects of germanium dioxide, an inhibitor of diatom growth, on the laboratory cultivation of Laminaria saccharina

Abstract: The kelp, Laminaria saccharina, is an economically and biologically valuable seaweed used in integrated multi-trophic aquaculture. The development of the initial microscopic phase of the life cycle of this species is carried out in the laboratory. A treatment of germanium dioxide (GeO2) can be applied to algal laboratory cultures to inhibit the growth of contaminating diatoms. Previous studies reported inhibitory effects also affecting the macroscopic stage of the life cycle of L. saccharina, the sporophyte, but the effects on the microscopic gametophytic life stage are unknown. To determine the effects, cultures of L. saccharina were treated with varying concentrations of GeO2 and the resulting lengths and surface area of the juvenile sporophytes produced were measured.

It was determined that GeO2 follows a typical dose effect, increasing the growth rate of sporophytes until a critical point at which an inhibitory effect on sporophyte growth was observed. To obtain juvenile sporophytes ready for deployment to aquaculture sites in the shortest amount of time, and to successfully reduce diatom contamination, it was determined that a concentration between 0.10 and 0.50 ml of GeO2 per litre of seawater, applied at day 8, was the most efficient.

Ryan Shea being one with the water, at an IMTA site in the Bay of Fundy, Canada (photo: Thierry Chopin).

M.Sc.: 2005 - 2008

Thesis: Design of an efficient raft from the nutrient perspective for the cultivation of Saccharina latissima and Alaria esculenta, two seaweeds used as the inorganic extractive component of an integrated multi-trophic aquaculture system

Abstract: Concerns of a point source and edge effects in nutrient uptake and their implications on bioremediation have been raised in the design of a raft unit for the cultivation of seaweeds in an integrated multi-trophic aquaculture setting. In order to observe if these effects are occurring, a seaweed raft, culturing Saccharina latissima and Alaria esculenta, was designed and four of these rafts were deployed at two aquaculture sites at Back Bay, New Brunswick, located in the Bay of Fundy, Canada. Sampling was conducted in a grid-like plot across the rafts and the nitrogen (N) and phosphorus (P) contents were analyzed. It was determined that there was no significant difference (a = 0.05) in the N and P contents of both species of kelps throughout the raft, at neither aquaculture site, therefore there was no support for a point source or an edge effect. However, concerns on the structural stability and logistics of using the current raft design to withstand the strong tidal forces and weather in the Bay of Fundy were raised. The nutrient content and the growth rate of the kelps was observed to be highest during the early spring and steadily declined throughout the summer. The biomass of the kelps increased over the spring/early summer season, peaking in July and then decreased once the growth rate could no longer compensate for the rate of frondal erosion.