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Milford Lab: Aquaculture Research

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Improving Microalgal Mass Culture
Microalgal culture greenhouse at Milford

The Greenhouse for Research on Algal Mass Production Systems (GRAMPS) was designed and constructed to research culture methods, techniques, and strategies of growing large quantities of microalgal biomass for such uses as in hatcheries to feed shellfish, to feed zooplankton eaten by finfish larvae, and in biofuels and other novel products. From its curved, sun-facing surface, which maximizes light usage, to computer monitoring and control systems, and modular culture apparatus, GRAMPS is a unique research asset.

Original research focused on long-duration, stable culture production (over 6 months at a time), which led to the installation of increasingly sophisticated monitoring and control systems that can help understand how microalgal cultures behave during natural day and night cycles, and how to optimize nutrient usage while maximizing production.

Ongoing research furthers the ability to grow algae in the most reliable, productive, economical, and environmentally-friendly way possible.

For more information, contact Barry Smith.

Molluscan Aquaculture Research
Covered tank and outdoor seawater system at Milford

Developing sustainable methods for rearing shellfish to meet the growing national demand for nutritious, protein rich seafood is one of the goals of the Milford Laboratory.  These methods include using technological advances to improve shellfish hatchery economics, while decreasing environmental impacts.  Ongoing research is examining the feasibility of using a computer controlled feeding system to rear larvae at high densities in semi-static  systems to maximize growth using minimal water. Trials are also underway in which specific nutritional supplements are added to a traditional hatchery feed in the hopes that it will enhance growth and alleviate a response to common stressors (i.e. high temperature or disturbance from handling).  We are also developing biochemical assays to measure stress in these animals in order to better quantify the effectiveness of these rearing conditions and dietary supplements.  We hope the output of these research projects will be utilized to enhance growth and survival in a commercial hatchery setting.

For more information, contact Lisa Milke.

Shellfish Immune Status

Hemocytes, essentially blood cells, in bivalves such as oysters, clams, scallops, and mussels, are responsible for various physiological functions including immune defense, nutrition, and waste disposal.   By understanding the functions and responses of these cells to environmental conditions, we are able to gain insight into the ability of hemocytes to maintain health when exposed to environmental stresses.   We are able to achieve this understanding with the use of physiological probes, coupled with microscopy and flow cytometric applications in both laboratory and field settings.  Eastern oysters, northern quahogs, bay scallops, blue mussels, and soft-shell clams, all species of economic or ecological importance in coastal habitats, are being studied.  Current projects include:  1) a multi-species study aimed at understanding variations in hemocyte immune competence in response to seasonal cycles, and 2) measuring the effects of ocean acidification on hemocyte physiology.  Ultimately, an improved understanding of the effects of changing environmental conditions on the health of farmed and wild-harvest shellfish will aid in local and national decision making.

For more information, contact April Croxton.

Probiotic Bacteria for Use in Shellfish Hatcheries

Hatchery production of bivalve shellfish seed for commercial grow-out or restoration can be constrained by bacteriosis in tank-cultured larval stages.  Environmentally-friendly methods for controlling microbial pathogenesis with probiotic bacteria are becoming increasingly preferred over repeated use of antibiotics, which can select for resistant pathogens in the environment.  Research at the Milford Laboratory has identified a Vibrio sp. bacterium (OY15), isolated from oysters, that significantly improves survival of larval oysters (Crassostrea virginica) challenged with a Vibrio sp. shellfish-larval pathogen (B183).  Possible mechanisms of OY15’s probiotic effect appear to be stimulation of immune function.  Studies to confirm that probiotic bacteria generally are effective because of immune-stimulation have been completed using gene-expression analysis to demonstrate regulation of certain immune genes in larvae following treatment with OY15.  Based upon these results, we will develop a functionally-based screening protocol for testing of probiotic candidates employing these in vitro immune-function assays using hemocytes from adult bivalves.  Molluscan shellfish hatcheries across the U.S. will benefit from eventual availability of probiotic bacteria as a component of “functional feeds,” to increase seed production, and will contribute directly to the objectives of the NOAA Shellfish Initiative.

For more information, contact Diane Kapareiko.

Shellfish Genetics

A major focus of the Genetics research program is to investigate the application of genetics and breeding technology for improving growth and survival of economically and ecologically valuable shellfish, which have declined, such as bay scallops. Results could contribute to increased commercial production, recreational harvesting, and reduced imports.  Three major approaches are being explored for culture, enhancement and restoration:breeding, population or molecular genetics, and field evaluations.  Responses to selective breeding, inbreeding and hybridization are being determined by developing lines for increased growth and survival, with positive results previously with oysters and currently with scallops.  In addition, genetic diversity of various stocks and populations is being ascertained with molecular technology to support or complement breeding and broodstock management.  Molecular (e.g., DNA) analyses are investigated for genotypic markers and expression in stock identification, with innovative biotechnology methods applicable to other shellfish species and different marine organisms from bacteria to fish. Habitat and environmental suitability and field performance evaluations also are being conducted with phenotypic markers such as striped shells credited to us. Observations are made on differences in growth and survival of shellfish under various conditions, comprising laboratory and field components. There are collaboration, outreach, resource and technology transfer activities.

For more information, contact Sheila Stiles.

Finfish Aquaculture research

We are developing practical aquaculture methods for the black sea bass, Centropristis striata, in recirculating aquaculture systems (RAS). This involves spawning fish both in and out-of-season using photo-thermal manipulation, determining the best conditions for growing embryos, larvae, and juveniles, and evaluating growth and development of larvae and juveniles fed natural and artificial feeds.  Black sea bass cultured in our RAS attained weights in less than 2 years that take wild fish to achieve in 3 years, or more.  These methods will be helpful in the development of commercial hatcheries for a growing US aquaculture industry. The fish grown here may also be used in feasibility studies for enhancement, or restoration of natural stocks.

Research is also focused on scup Stenotomus chrysops, another potential aquaculture species.  Studies have been conducted on the growth of juveniles fed commercial diets.  Juvenile scup exhibited high specific growth rates between 5.6-6.6% day and had very high survival rates under culture conditions. Scup are a very hardy species, tolerating handling, and acclimating quickly to tank conditions in the laboratory. Results from our research indicate the high potential value of this species for commercial aquaculture.  Future research efforts will include investigating temperature, lighting, reproductive physiology, alternative feeds, and nutrition.

For more information, contact Dean Perry.

RNA/DNA as a Growth Index

The use of nucleic acid indices as indicators of recent growth and nutritional condition in juvenile fish is based on the premise that white muscle tissue RNA concentration corresponds to changes in protein synthesis rate and somatic growth while DNA concentration or cell number, remains relatively constant. RNA:DNA  ratio and RNA concentration respond quickly to changes in feeding rate or food availability and offer an alternative to somatic growth measurements. In the laboratory, nucleic acid indices can be used to assess condition of fish fed different diet formulations and ration amounts, and can be used to evaluate rearing protocols. Nucleic acid measurements of field collected fish can help determine habitat suitability for release of fish for enhancement and can be used to estimate recent growth of young fish. Validating the nucleic acid growth relation for particular species, body sizes and life stages of interest allow indices to be applied in an aquaculture setting. Studies have been conducted at Milford Laboratory evaluating the nucleic acid growth relation in a variety of fish species including winter flounder, tautog, scup and cunner.

For more information, contact Renee Mercaldo-Allen.

Merging Modeling and Mapping to Improve Aquaculture Siting

This project is designed to improve the decision-making process for marine aquaculture in multi-use areas by merging two types of tools: modeling and mapping. Specifically, we are integrating the Farm Aquaculture Resource Management (FARM) model into the existing Shellfisheries Mapping Atlas. The Atlas is an interactive, online GIS-based tool for marine aquaculture that provides maps on general site characteristics (e.g. bathymetry), assesses potential use conflicts (e.g. commercial fishing) and environmental interactions (e.g. presence of submerged aquatic vegetation). The FARM model combines physical and biogeochemical models, shellfish growth models and an eutrophication screening model. It evaluates the success of aquaculture (i.e. growth of shellfish), the impact of a farm on water quality, provides economic analysis of potential production, and assesses potential credits for carbon and nitrogen trading. The FARM model is being used to evaluate the suitability of three geographically distinct sites within Connecticut to support aquaculture, by estimating the time for shellfish to grow to market size from hatchery spat.  This project has benefited from leveraging ongoing local water quality monitoring programs in Stonington and Westport, CT to fill data needs for the model. Results will be integrated as a map layer into The Atlas, resulting in an improved capability for resource managers, farmers, individuals and organizations involved in stock enhancement or restoration projects to successfully plan aquaculture or restoration activities within this multi-use estuary.

For more information, contact Julie Rose.
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(File Modified Jun. 07 2016)