Saturday 20. September 2014

Impact of Invasive Flora Species in Seagrass Meadows on Fish Assemblage

On Tuesday, September 23, at 16:30, Victor Buchet will present his master's thesis in Coastal and Marine Management, titled: Impact assessment of invasive flora species in the Posidonia oceanica meadows on fish assemblage. An influence on local fisheries? The case study of Lipsi Island, Greece

His thesis advisor is Michael Honeth (M.M.M.), Ocean Resource Coordinator at Tobacco Caye Marine Station, American Samoa Government in Belize. The reader is Dr Zoi Konstantinou, Science Officer at Eurocean in Lisbon, Portugal and instructor at the University Centre of the Westfjords, Iceland.

The presentation takes place in room 6 at UW and everyone is welcome.


Seagrasses are one of the most valuable coastal ecosystems with regards to biodiversity and ecological services, whose diminishing presence plays a significant role in the availability of resources for local communities and human well-being. At the same time, Invasive Alien Species (IAS) are considered as one of the biggest threats to marine worldwide biodiversity. In the Mediterranean, the issue of IAS is one which merits immediate attention; where habitat alteration caused by the human-mediated arrival of new species is a common concern. Indeed the Mediterranean Sea is considered to be one of the main hotspots of marine bio-invasions on earth. In this context, the present study examines the possible impacts of flora Invasive Alien Species on the fish assemblages associated with Posidonia oceanica seagrass habitat, and the possible impacts that any change might have on local fisheries. The setting for this study is Lipsi Island, in the Dodecanese, Greece. In situ, Underwater Visual Census’s (UVC) were carried out at 14 sampling sites. Fish community parameters were estimated across three substrate types: dense P. oceanica, sparse P. oceanica and sparse invaded (by IAS flora) P. oceanica. External factors and percentage of flora cover were estimated for each substrate. Two flora IAS were found: Halophila stipulacea, one of the first species introduced in the region, which arrived after the Suez Canal opening (also known as a Lessepsian migrant), and Caulerpa cylindracea, a recent introduction through an unknown vector. The present study on the finfish assemblage around Lipsi Island supports the findings of similar studies undertaken in the Mediterranean. The results of the present study show that a low percentage of IAS does not have a significant impact on the finfish assemblage and thus does not seem to have had a significant impact on the local artisanal fishery. With little previous work in the region and no previous work on the Island, this study provides a baseline for future evaluation of changes produced by IAS and for potential management actions such as the creation of marine protected areas in the study region.