WSC2018 Talks: ISBW079 - Differences in traits between native and invasive Halophila stipulacea

Presented by Dr. Gidon Winters The Dead Sea Arava Science Center, Tamar regional Council Recorded on 13 June 2018 Abstract Halophila stipulacea is a tropical seagrass, native to the Red Sea, Persian Gulf and Indian Ocean. Following the opening of the Suez Canal, this species became a Lessepsian migrant and has since spread to most of the eastern Mediterranean Sea. Recently, this species has reached the Caribbean where alarming studies showed H. stipulacea displacing local Caribbean seagrass species. Aiming to deepen our understanding of the invasiveness of H. stipulacea, we recently setup identical permanent monitoring transects at similar depths in both the native (Eilat, Israel) and invasive (Limassol, Cyprus) habitats. Samples were collected in parallel from both sites four times during 2017 and were used for comparisons of morphological, physiological and flowering traits, alongside sampling the microbiome associated with H. stipulacea plants in each site. Above ground biomass and percent cover were higher year-round in Eilat than in Limassol, reaching a maximum in July (Eilat) and October (Limassol). Leaves in Eilat were larger than in Cyprus, however Limassol plants had more apical shoots and larger internodes. H. stipulacea plants were female-biased in Eilat, compared with the invasive male-biased populations. Microbiome epiphyte communities associated with H. stipulacea leaves differed between sites and corresponded to the dominant microbial genus present in seawater at each site. Taken together, results suggest that invasive (Cyprus) and native (Israel) plants are morphologically different. Invasive plants were smaller, had more apical shoots and larger internodes than their native counterparts. Flowering plasticity in Cyprus, might help H. stipulacea’s ongoing expansion in the Mediterranean, thereby threatening local seagrasses species.