The colonial protochordate, Botryllus schlosseri, undergoes a genetically defined, natural transplantation reaction when the edges of two growing colonies interact. Peripheral blood vessels of each colony touch and will either fuse together to form a common vasculature between the colonies, or reject each other in an active blood-based inflammatory process in which the interacting vessels are c...

The relative importance of multiple vectors to the initial establishment, spread and population dynamics of invasive species remains poorly understood. This study used molecular methods to clarify the roles of commercial shipping and recreational boating in the invasion by the cosmopolitan tunicate, Botryllus schlosseri. We evaluated (i) single vs. multiple introduction scenarios, (ii) the rela...

An invasive colonial ascidian, Didemnum sp. [described as Didemnum lahillei by Lambert (2004) and Didemnum vestum by Kott (2004) and ecologically similar to Didemnum vexillum (Kott, 2002)], has occupied unusually large areas of seafloor and spread rapidly throughout the New England region (Valentine et al., 2007-this issue; Bullard et al., 2007-this issue). Its extreme abundance at depthsN30 m ...

Hypoxia is increasing in marine and estuarine systems worldwide, primarily due to anthropogenic causes. Periodic hypoxia represents a pulse disturbance, with the potential to restructure estuarine biotic communities. We chose the shallow, epifaunal community in the lower Chesapeake Bay, Virginia, USA, to test the hypothesis that low dissolved oxygen (DO) (<4 mg l–1) affects community dynamics b...