Detritus as Nutritional Supplement for Bivalves

Project Description

Determining the quantity and quality of seston present in Saco Bay is a key factor in evaluating its environmental carrying capacity for sustainable ecological aquaculture (SEA). This baseline data is being collected by SEANET through the use of the buoy network, field surveys, and laboratory analyses. This addresses the environmental carrying capacities of SEA in the Gulf of Maine by: (1) quantifying temporal and spatial variability of labile seston, with a focus on detritus to inform optimum shellfish production areas; (2) determining the origins of detrital input through the use of stable isotopes; and (3) quantifying the extent of changes in quality and quantity of seston as it passes through bivalve aquaculture farms.

Knowledge of the spatial and temporal variability of seston quantity, quality, and sourcing will be a powerful management and modeling tool for the development of SEA in Saco Bay. Understanding how SEA can change available seston will allow for better environmental management and provide insight into what ecological changes may occur.

Results and Accomplishments

Project personnel conducted transect sampling in Saco Bay and the Damariscotta River to collect water samples for flowcam and flow cytometry analyses by Bigelow Ocean Laboratories. The samples were analyzed for particulate organic carbon, zooplankton composition, and detrital carbon. In Saco Bay, researchers collected mussels to determine if utilization corresponds to spatial variations in detritus. Stable isotope samples from Saco Bay are sent to the UC Davis Stable Isotope Facility for analysis.

Researchers investigated the quality and quantity of terrigenous, salt marsh, and kelp detritus in the spatio-temporal patterns of water flows in Saco Bay and analyzed stable isotopes, bulk chemical composition, and lipids as a proxy for detritus quality. UNE researchers worked with UMaine researchers at the Darling Marine Center to develop robust models of detritus production to predict concentrations over a variety of seasons and coastal environments.

Major research findings of this project include:

  • Quantifying amount of detritus that is available and used by bivalves in Saco Bay.
  • Discovering timings of events specific to Saco Bay.
  • Quantifying the spring-fall diatom bloom in Saco.
  • Discovering smaller celled phytoplankton in the summer season.
  • Discovering spartina detritus in the fall season, as seen in carbon stable isotopes.
  • Discovering that mussels appear to be ingesting phytoplankton or phytodetritus.

 

Summary of Data Being Collected

Data Type Quantity Location
Lipid analysis and stable isotope analysis of kelp, salt marsh and phytoplankton detritus soruces Field Collected every 2 weeks Saco Bay
Water samples analyzed for suspended particulate matter, chlorophyll-a, plankton size fractions, flow cam for species ID, primary production (via C-14 method), isotope analysis, POC and PON Field Bi-weekly Saco Bay