Emily Nelson

MSc Candidate

Emily NelsonBSc Hon. Biology, University of New Brunswick Saint John
Contact: emily.nelson@unb.ca

Research: "Exploring the feeding physiology of the sea cucumber Cucumaria frondosa: implications to Integrated Multi-Trophic Aquaculture"

One of the major concerns surrounding aquaculture is its effect on the environment. In marine aquaculture excess food and faeces can lead to excessive organic loading on site beneath the cages, which changes the chemical composition of the substrate and the local biodiversity. 

Integrated multi-trophic aquaculture (IMTA) is one technique that has the potential to help reduce some of the environmental impacts and has been steadily gaining momentum in Canada. IMTA involves the culture of traditional finfish (e.g. salmon) but uses the waste products (excess feed and faeces) produced by the finfish as a food source for other commercially viable extractive species. 

Both inorganic extractive species (e.g. seaweeds) and organic extractive species (e.g. mussels) are grown in close proximity to the site to help mitigate the excess nutrients produced, while creating an additional cash crop for farmers.  Currently, there is a growing interest in using the commercially viable orange-footed sea cucumber (Cucumaria frondosa) as an additional organic extractive species in the IMTA system.

Within the literature sea cucumbers have been found to consistently reduce aquaculture wastes, but most of the sea cucumbers that have been studied are deposit feeders, which feed by ingesting sediment. However, Cucumaria frondosa is a passive suspension feeder that feeds on particles suspended in the water column.  Since deposit feeding sea cucumbers have effectively reduced organic loading at other sites it is believed that Cucumaria frondosa might have equal potential. 

Much of the feeding physiology that would be pertinent to its potential as an IMTA organic extractive organism is poorly understood. Within my project I will be examining two key aspects of feeding physiology that would pertain to IMTA.

Firstly, I will be quantifying the relationship between absorption efficiency and the quality (organic content) of the diet. This will be done through laboratory experiments as well as field trials where there is potential exposure to a combination of natural and farm-based particulates. Secondly, I will be quantifying the time it takes for food to be converted to faeces (gut passage time) in the laboratory as well as directly at an IMTA site.