Recirculating aquaculture system integration of bivalve culture for effluent nutrient composition reduction
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Amanda R. Myers (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Ami Wilbur
Abstract: Closed recirculating aquaculture systems (RAS) are a technological innovation that reduces
the amount of water needed for culture by treating and reusing up to 90% of the total water
volume daily. Such systems consequently produce substantially smaller volumes of effluent,
though it is enriched in nutrients relative to effluent from flow-through or open systems. For
RAS to emerge as a viable culture strategy, an economical and efficient method must be
developed to reduce effluent nutrient concentrations before discharge. As part of a larger project
evaluating biofilter effects on RAS effluent, this study focused on the effect of bivalve culture on
the composition of southern flounder RAS effluent. This system produces 1270 L/day of
effluent, with nutrient and suspended solids concentrations 20-100x that of ambient levels. Two
trials were conducted using this effluent as a nutrient base for bivalves stocked in an upwelling
system for four weeks. Trial I utilized raw effluent nutrients for two densities of oysters
(Crassostrea virginica, (average shell height ± standard error = 63.4 ± 1.7 mm). Trial II utilized
effluent inoculated with microalgae, Isochrysis galbana, as the nutrient base for two densities of
clams (Mercenaria mercenaria, average shell height ± standard error = 16.7 ± 0.2 mm).
Effluent nutrient composition (total nitrogen, total phosphorus, and total suspended solids) was
analyzed from samples (collected twice weekly) taken before and after bivalve filtration.
Change in shell height was quantified by measuring subsamples at the start and end of each trial.
Oysters did not have a significant impact (Wilcoxon-Mann-Whitney Test, p>0.05) on the RAS
effluent nutrient compositions in this flow-through integrated system. Clams, also, did not have
a significant impact (Wilcoxon-Mann-Whitney Test, p>0.05) on the RAS effluent nutrient
compositions. Significant change in shell height was not exhibited in the oysters (Wilcoxon-
Mann-Whitney and Welch-ANOVA Tests, p>0.05) over the time course of Trial I. Over the course of Trial II, a significant change in shell height was exhibited within treatments (Low:
p=0.01, High: p=0.049) and between clam densities (p=0.01). The magnitude of seawater
dilution, high flow rates, and high suspended solids loads may have inhibited my detection of
effluent composition reductions.
Recirculating aquaculture system integration of bivalve culture for effluent nutrient composition reduction
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Created on 1/1/2009
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
- Language: English
- Date: 2009
- Keywords
- Aquaculture--Water-supply, Bivalve culture, Bivalve culture--By-products, Bivalve culture--Waste disposal, Marine biotechnology, Sewage--Purification--Nutrient removal, Water--Purification--Biological treatment, Water reuse
- Subjects
- Aquaculture -- Water-supply
- Water reuse
- Bivalve culture
- Water -- Purification -- Biological treatment
- Sewage -- Purification -- Nutrient removal
- Bivalve culture -- Waste disposal
- Bivalve culture -- By-products
- Marine biotechnology