Andrews suggested that the ultimate fate of bivalve larvae is strongly dependent on current regimes and flushing rates of estuaries. In the James River estuary, horizontal and vertical circulation and turbulent mixing associated with a frontal system combine to enhance upstream transport of oyster larvae and, thus, contribute to larval retention. Physical transport processes that enhance larval retention play a critical role in successful recruitment of larval organisms within outflux-dominant estuaries. Physical transport, defined as larval transport not affected by larval characteristics but solely determined by physical processes, includes advection and turbulent mixing. Larval supply is influenced by a combination of physical transport and biological movement of larvae. For most marine invertebrates and fish this influx occurs during the planktonic larval stage and is a function of both concentrations of larvae in the water column and horizontal advection into the region, that is, larval supply. Persistence of exploitable populations of marine invertebrates and fish is dependent on a high influx of new recruits into a population. Inclusion of biological movement, however, caused little change in the overall patterns of larval transport and still resulted in a west-east gradient, presumably because of frequent destratification in the shallow Mobile Bay system. Biological movement increased larval retention near the spawning area, thus providing a favorable condition for local recruitment of oysters. A persistent gradient decreasing from west to east in the model results at time scales of overall average, season, and each survey in 2006 suggests that the larval supply may be responsible for the corresponding gradient in oyster spat settlement observed over the past 40 years.
![size of oyster spat size of oyster spat](https://d178ivhysawugh.cloudfront.net/1519478696/oyster-sc-5mm-spat-ready-for-sale-6-months-old.jpg)
The model reasonably reproduced the observed gradient in oyster spat settlement and bivalve larval concentration, although the model results were less dynamic than the data, probably owing to the simplified biological conditions employed in the model. Site- and larval-specific conditions, including spawning location, spawning stock size, spawning time, and larval period, were determined based on the previous studies. A hydrodynamic model was used to simulate physical transport, and biological movement was parameterized as a function of swimming and sinking velocity of oyster larvae. A three-dimensional larval transport model accounting for physical transport, biological movement of larvae, and site- and larval-specific conditions was developed.
![size of oyster spat size of oyster spat](https://c8.alamy.com/comp/KT2H3M/34884-oyster-spat-or-set-two-or-three-weeks-old-on-inside-of-oyster-KT2H3M.jpg)
Here we conducted a field and modeling study to investigate the larval transport of eastern oyster, Crassostrea virginica, in Mobile Bay and eastern Mississippi Sound, Alabama. If you are interested in volunteering with the Great Bay Oyster Restoration program or other environmental stewardship programs, reach out to the New England Stewardship Network.Among the various factors affecting recruitment of marine invertebrates and fish, larval transport may produce spatial and temporal patterns of abundance that are important determinants of management strategies.
![size of oyster spat size of oyster spat](https://delicia.sg/wp-content/uploads/2020/10/Tsarskaya-Oyster-open-1533x1536.jpg)
![size of oyster spat size of oyster spat](https://sc01.alicdn.com/kf/UTB8Ad5SXpPJXKJkSahV760yzFXai/200113423/UTB8Ad5SXpPJXKJkSahV760yzFXai.png)
We helped by volunteering a few hours on a sunny morning to count oyster spats that will be delivered to local homeowners that will monitor their growth. Now about 8 years underway there is a community effort to restore the oyster population. During the 1980s a deadly disease was introduced to the region that destroyed most of the oyster beds. The oysters were key to the health of the estuary. Great Bay had a long tradition of large populations of oysters that helped filter and clean the waters. Curious what an oyster spat is? Well, it's a baby oyster and UNH has teamed up the The Nature Conservancy and volunteer Oyster Conservationist to help repopulate this body of water with oysters. Although a majority of our projects are completed in the Lakes Region, this past July we were able to spend a morning at the UNH Jackson Estuarine Laboratory on the shores of the Great Bay in Durham to help count oyster spats.