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

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

Aquatic Ecosystem Health and Management Society - AEHMS

The non-indigenous cheilostome bryozoan Conopeum seurati Canu was found growing on Spartina alterniflora stems at Villa del Mar (Bahia Blanca estuary, Argentina, southwest Atlantic), an estuarine environment. C. seurati is a typical species of brackish estuarine environments, supporting a wide range of salinities. It typically grows on aquatic plants, which is its most characteristic substrate. It typically occurs in Northern Europe and in the 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 was recorded, and the associated fauna living at the colonies was quantified and identified.C. seurati density in the salt marsh was about 100 colonies per square meter, and we observed a negative effect of C. seurati on Spartina, killing plants by strangulation. About 25 different invertebrate species were living in C. seurati colonies, at least 3 of them being invasive species (the sea anemone Diadumene lineata, the isopod Sphaeroma serratum and the oyster Crasostrega gigas).This species seems to have the potential to continue its dispersion and become a stable component of the intertidal communities in the area. It is necessary to perform experimental studies to determine the mechanism that could explain Spartina die-off by C. seurati.