Browsing by Author "Seyer, Thomas"
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- First record of the nudibranch tenellia adspersa (Nordmann, 1845) in Portugal, associated with the invasive hydrozoan cordylophora caspia (Pallas, 1771)Publication . Encarnação, João; Seyer, Thomas; Teodosio, Maria; Leitão, FranciscoThe estuarine nudibranch Tenellia adspersa (Nordmann, 1845) was recorded for the first time in Portugal, while sampling for fouling fauna of artificial structures along the salinity gradient of the Guadiana estuary (SW Iberian Peninsula). Two specimens were found in association with the invasive hydrozoan Cordylophora caspia (Pallas, 1771) and kept in the laboratory for taxonomy purposes. After two days, batches of eggs were seen in C. caspia branches, while the nudibranchs were also actively feeding on the hydrozoan polyps. The fast generation times of T. adspersa, along with its food preference for C. caspia, might suggest a positive role of the nudibranch on controlling this invasive hydrozoan in the Guadiana estuary. Introduction routes and facilitation interactions are discussed.
- On the presence of the Ponto-Caspian hydrozoan Cordylophora caspia (Pallas, 1771) in an Iberian estuary: highlights on the introduction vectors and invasion routesPublication . Seyer, Thomas; Morais, Pedro; Amorim, Katherine; Leitão, Francisco; Martins, Flavio; Teodosio, MariaSeveral non-native invertebrate and vertebrate species have been detected in the Guadiana Estuary (SW-Iberian Peninsula, Europe) during the 21st century. In June 2015, the non-native hydroid Cordylophora caspia (Pallas, 1771) was detected for the first time in this estuary, which motivated an assessment of its distribution during late Spring and Summer 2016. The main goals of this paper were to: i) report the presence of Cordylophora caspia and its distribution in the Guadiana Estuary, ii) record the substrates colonized, salinity, and water temperatures at locations where the species was detected, iii) evaluate possible introduction vectors and invasion routes; and iv) discuss the potential impacts and management options. Cordylophora caspia occupied a 25-km stretch of the estuary with salinities between 0.2 and 13.8 and occupied a variety of human-made substrates. Shipping was the most likely introduction vector of C. caspia, which might have originated from populations in the Atlantic Ocean or the Mediterranean Sea. Currently, the potential ecological impacts are likely low since the population size is small due to an apparent shortage of suitable habitat. Economic effects are minimal at present because there are no major industries along the basin extracting water from the estuary. An integrated ecohydrological approach-i.e. freshets released from dams to control the populations of Cnidaria-was proposed to minimize or mitigate the potential negative effects of this species in the Guadiana Estuary.