Adventures in low salinity

December 5, 2013

ABC recently completed a study comparing 13 different constructs of triploids with their diploid counterparts.  There were a couple of bottom lines.  First, location, location, location.  The relative value of triploids is highly dependent on where they are grown.  At the lowest salinity (the Horn Point Lab in the Choptank River), there seems to be no value.  Second, triploids made with our tetraploid line float all boats, including wild oysters, except in low salinity.  What is it about low salinity that ‘retards’ triploids?

Through our regular breeding activities, we have clearly shown the need for having multiple lines to deal with various salinity (and hence, disease) ranges.  Lines bred in lower salinity areas (leases kindly provided by the Bevan’s Oyster Company, and more recently, Cowart Seafood) have shown adaptation to this environment and perform better than their mesohaline counterparts.  The Lola line in particular is highly productive in low salinity.  Interestingly, the Lola line is also quite good in other areas, as long as the disease pressure is not high – it would be a risky business for an oyster farm to use Lola where disease might appear, despite Lola’s edge.Screen Shot 2013-12-17 at 2.19.34 PM

We hypothesize that pushing breeding to the lower edges of the salinity range will actually improve the overall physiological performance of our lines over and above the breeding we could attain in the middle of the Bay alone.

Therefore, we are about to embark on a new chapter of breeding activity, a confluence of three events that are coinciding.  The first event is the data that we obtained from the triploid project that screams, “lower extremes of salinity in the Bay need special consideration.”

The second event is the advent of ABC’s transition to family breeding.  In short, in the future, we are going to make breeding progress by testing numerous families, instead of lines.  In the York River, we are about to install an Australian long-line system (right under the window of the Dean and Director’s office) because we see this system as the perfect option for family deployments.  Each basket can accommodate around 75-80 oysters at market size and growing conditions among baskets are much more uniform than bags.  It also looks cool, although this system is probably not right for Bay aquaculture writ large.

The third event is the recent addition of a new faculty member at University of Maryland’s Center for Environmental Science at Horn Point.  Louis Plough has a pedigree in oyster research beginning with his Doctorate at the University of Southern California in Dr. Dennis Hedgecock’s lab.  He started at Horn Point this year with expertise in population genetics of marine animals, quantitative genetics, and experimental breeding of shellfish.  ABC has had a long standing collaboration (i.e., as long as we have existed) with the Horn Point lab through Dr. Don (Mutt) Meritt; the addition of Louis to the breeding portfolio of the Bay enriches this collaboration all the more.  And coincidentally, his arrival coincides with our realization that low salinity is another ‘disease’ that should be addressed with our family breeding.  We have entered a collaborative arrangement with Horn Point, through Mutt and Louis, to build a second Australian long line system in the Choptank River.

This new endeavor into low salinity is somewhat unprecedented in oyster breeding.  Few places in the world where oysters are farmed face issues of low salinity – the Chesapeake is unusual in that regard.  Therefore, other breeding programs in the world never delve into the netherworld of salinities lower than, perhaps, 25 ppt.  We are going into the ‘salinity basement’ of 8-10 ppt.  We will see what these adventures in low salinity reap in terms of newer, more robust, lines of farmed oysters.