Biogenic structures of a non-native bryozoan increase colonization by invasive species and cause Spartina alterniflora die-off.

LUCAS M. MOLINA.; JUAN JOSE LOPEZ GAPPA

Buenos Aires

Simposio; Marine & Freshwater Invasive Species: Ecology, Impact, and Management (MFIS); 2016

Aquatic Ecosystem Health and Management Society (AEHMS)

The non-indigenous cheilostome bryozoan Conopeum seurati Canuwas found growing on Spartina alterniflora stems at Villa del Mar (BahiaBlanca estuary, Argentina, southwest Atlantic), an estuarine environment. C.seurati is a typical species of brackish estuarine environments, supportinga wide range of salinities. It typically grows on aquatic plants, which is itsmost characteristic substrate. It typically occurs in Northern Europe and inthe Mediterranean. We recorded a widespread colonization of Spartina stems by C. seurati (forming ?finger shaped?colonies, each colony composed of several layers) at the saltmarsh under study.The number of plants overgrown by C. seurati per square meter wasrecorded, and the associated fauna living at the colonies was quantified andidentified. C. seurati density in the salt marsh was about 100colonies per square meter, and we observed a negative effect of C. seurati onSpartina, killing plants by strangulation. About 25 different invertebratespecies were living in C. seurati colonies, at least 3 of them beinginvasive species (the sea anemone Diadumene lineata, the isopod Sphaeromaserratum and the oyster Crasostrega gigas). This species seems to have the potential to continueits dispersion and become a stable component of the intertidal communities inthe area. It is necessary to perform experimental studies to determine themechanism that could explain Spartinadie-off by C. seurati.