NCCOS Project Explorer (NPE)

Propogation, prevalence, and impacts of invasive tunicates(2009)

Project Description:
The establishment of invasive tunicates in New England waters has steadily increased over the past three decades. High densities of solitary invasive tunicates are causing heavy biofouling in shellfish aquaculture likely resulting in substatial decreases in profits. Furthermore, colonial tunicates such as Didemnum vexillum, have become established and spreading along the New England coast with high prevalence on the Georges Bank. Didemnum vexillum poses a considerable threat to commercially important species and may adversely affect larval recruitment of native fauna such as sea scallops (Plactopecten magellanicus). This interaction could impact the sea scallop fishery, which reported a value of $430 million in 2005. The propagation, prevalence,and impacts of invasive tunicates, both solitary and colonial, are poorly understood. For this reason we are conducting laboratory and field observations capable of assessing where invasive tunicates are occuring, how many are there, and impacts on native fauna and shellfish aquaculture. We are conducting laboratory studies investigating the interactions of settling scallops and colonial tunicates and are also assessing propogation mechanisms through fragment viability.

Expected Outcome:
This project will assess invasive tunicate prevalence and will provide coastal managers with a quantitative census on impacts of invasive tunicates on native fauna and shellfish aquaculture. Our laboratory studies will test the temporal and spatial components of fragmentation, and whether fragments contribute to sexual reproduction. We will (a) record mechanisms by which fragmentation occurs in the course of human activity; (b) determine how long fragments are viable; (c) calculate how far viable fragments potentially can move under field conditions, and (d) determine the seasonality of fragmentation, reproduction, and differentiation of colonies. These data, combined with our previous study on the negative effects of Didemnum sp. on shellfish larvae, will provide managers and aquaculturists with information on when and where physical disturbance will have the greatest impacts and how to avoid these impacts.