Out with the old…
In a classic fieldwork moment, I had just finished setting up one system for my broodstock, when a newly published paper and a phone chat changed my mind and I had to almost completely redo it. Initially, I had decided to split my adults into 4 or 5 buckets per population of ~25 oysters each in order to maximize genetic diversity by minimizing the chance of one male fertilizing all females. I built a manifold for this system (new term I learned meaning “pipe branching into several openings”) and had 0.5 gal/hour drippers delivering 16degC seawater and algae to the buckets. The broodstock were taken out of their combined tank on Tues. May 31 and separated into a single 5 gal bucket per population. They were split up into ~25 per bucket on Wed. June 15, with 4 buckets for California and 5 buckets each for BC and OR. My cleaning schedule for buckets was to rinse them and wash with Vortexx 3 times a week, and change out the drippers every day I was at the hatchery with ones that had been sitting overnight in Vortexx.
Then on Friday June 17 I read this new paper out of George Waldbusser’s lab at OSU. They conducted a carbonate chemistry manipulation experiment with fertilized eggs extracted from brooding Olympia oysters. A quick reminder- male Olympia oysters release sperm into the water column which is then filtered out by females for fertilization. The females then keep the fertilized eggs in their mantle cavity for up to 12 days before releasing the now weakly swimming larvae. In Waldbusser et al. 2016,they found that larvae extracted ~36 hours after fertilization developed at a similar rate as larvae left in the brood chamber. As far as I know, this was one of the first experiments where Ostrea larvae had been raised outside of the brood. In order to identify a newly fertilized female, they looked for eggs that had been essentially spit out by an adult oyster. Chatting with Matthew Gray from the project was really helpful in figuring out how I can adapt my system to identify brooding females and possibly try to run some experiments of my own on newly fertilized larvae.
…in with the new
On Thursday June 23, I did away with most of the buckets and laid out oysters 2″ apart in black plastic 9 gal tubs (originally meant for cement mixing), with 40-50 oysters per tub and 3 tubs for BC and 2 tubs for CA and OR making 7 tubs total. This number was primarily dictated by space, or else I would’ve split them up into more trays. Some oysters were stuck together in a way that made it impossible to separate without killing them, and so were put in 3gal buckets with small 100 um banjo filters. Each tray has an airstone, either two 1/2 gal/hour drippers or a single 1 gal/hour dripper, and a banjo filter.
Cleaning these trays is a pain as they are too heavy and awkward to pick up and pour out into a bucket, so we use a hose to drain the tray into a bucket and keep the broodstock in a clam bag and separate bucket of seawater during cleaning and filtering for larvae. As we screened out the first batch of larvae on Thursday, we will be cleaning all trays/buckets every day to check for larvae. The official start of the experiment will be when all three populations are releasing enough larvae.