About This Project

Every oyster that humanity has consumed started as a miniscule larva, invisible to the naked eye. During these stages, the larvae are most sensitive and reliant on the lipids they receive from phytoplankton. In fact, over 30% of the larvae die before they reach adulthood. We hypothesize that our novel phytoplankton blend using optimized algal sizes will result in higher survival and settlement rates of oyster larvae compared to the industry-standard algal concentrate.

Ask the Scientists

What is the context of this research?

The oyster market represents over 4 billion dollars annually. In order to produce viable spat capable of turning into marketable oysters, they need to be fed a varied microalgae blend.

Oysters are unable to synthesize enough sterols and other fatty acids to survive; failure to provide larvae with sufficient polyunsaturated fatty acids results in deformities. Microalgae blends are preferred over monocultures as they introduce a more varied lipid profile, but the chosen species must together cover EPA, ARA, and DHA fatty acid profiles. Metamorphosis of the Pediveliger stage to spat is extremely energy intensive and is where reserves of neutral lipids (Triglycerides) are required to survive the 48 hour period, with a 41-91% survival rate.

Furthermore, I have introduced a novel idea of tailored stage-specific feeding, which reduces energy expenditure on rejecting microalgae that are too large.

What is the significance of this project?

Going back to the stage-specific feeding, newly hatched oyster larvae have a feeding organ called a velum, which is a ciliated organ used to ingest microalgae. However, this organ can only ingest phytoplankton 5-8 microns, meaning anything bigger is wasted.

My idea is to assign ratios of microalgae that are ingestible by a given stage of larvae.

For example, the D-Stage larvae ratio should be 50% Isochrysis, 25% Pavlova, and 25% Rhodomonas for accessible cell size and polyunsaturated fatty acids. Using this novel formulation and feeding method, I want to compare this live blend to a whole cell concentrate primarily used by oyster hatcheries today.

This research is significant to help bivalve hatcheries as a whole achieve increased settlement rates and survival rates. By making our data open source, hatchery managers will be able to feed their bivalve larvae at a lower cost than purchasing concentrates while ensuring comprehensive nutrition at all life stages.

What are the goals of the project?

Firstly, I will culture 5 strains of the algae on a 12:12 grow cycle in aerated saltwater 1 gallon carboys fed with F/2 Medium. We will only use distilled water and autoclaved instruments. There will be 10,000 larvae in two separated carboys with aeration. One group will be fed with the recommended feeding dosage of the algae concentrate, the other will be my strained 5-strain phytoplankton blend at 3 million cells per mL. Right after the larvae reach pediveliger stage indicated by a visible foot and eyespot, we will present an attachable substrate of crushed oyster shells, then evaluate the settlement rate.

I will then assess settlement rates and survival rates using averages per mL using a hemocytometer and microscope.

I plan to achieve a 90% survival rate before the larvae metamorphosize, and at at least a 50% settlement rate.

This will be repeated three times to ensure accurate results.