Wednesday, August 29, 2012

Didemnum really is a tough guy!

I recently published an article on the invasive species Didemnum vexillum. In the article published in the journal Marine Biology I and colleagues characterize the material properties of the invasive sea squirt. D. vexillum is a particularly troublesome invasive species because it has colonized broad areas of Essential Fish Habitat on Georges Bank, and can directly impact sea scallops that use that habitat.  Understanding the material properties of D. vexillum can help understand why it has so successfully colonized habitats where other sea squirts are excluded and its potential to disperse to new habitats by fragmentation (breaking in to smaller pieces and floating with the water currents ). Compared to other colonial sea squirts D. vexillum is extremely tough, meaning that it is hard to break apart. It’s tough tunic may enable D. vexillum to cement together pebble-cobble substrates, and prevent the sediments from shifting around. The stabilization of substrate may allow further colonization of these habitats and act as a positive feedback! The changes in the infauna (e.g. worms and amphipods) associated with sediment stabilization have some classifying D. vexillum as an ecosystem engineer.  Additionally, organism (e.g., sea scallops) that typically settle on those pebble-cobble substrate will have less space to settle. Ultimately understanding these life history characteristics may help to develop management practices for controlling D. vexillum.

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