Many studies in marine coastal lagoons have focused on the marine-to-terrestrial gradient as a main source of variation for the structure of assemblages. In this paper, the magnitude of differences among locations arranged along the marine-to-terrestrial gradient of the western lagoon of Orbetello (Grosseto, Italy) was contrasted with the amount of spatial variability occurring among sets of locations that were not positioned along this axis. We propose that if the most important processes influencing assemblages were those associated with the external-internal gradient of the lagoon, as usually supposed, then assemblages should differ more among these locations than among any other locations. To test the above proposition, four locations arranged along the two major axes of the lagoon were established in November 2000. Each location was sampled three times (

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The red alga Kappaphycus alvarezii (Doty ex P.C. Silva, 1996) has been intentionally introduced throughout the tropics for mariculture. In some cases, the alga has spread outside cultivation sites and impacts native biota. We conducted surveys of two sites in Bocas del Toro, Panama, where non-native K. alvarezii was previously cultivated to determine whether it is established and began to examine potential interactions with native biota. We found that non-native K. alvarezii has spread into adjacent seagrass beds, mangroves, and coral patches. The cover of K. alvarezii at these sites can be high (>30%), and it appears to smother seagrass, coral, and sponges. However, herbivory by native sea urchins may act as an important agent of biotic resistance, though additional evidence is needed to confirm this.

Abstract. The population ecology and dynamics of Cuprella equilibra were studied in a lagoon estuary of the Northern Adriatic Sea during 1985 to 1986. The breeding activity showed peaks in April and September and a decrease in summer due both to high temperatures and a dystrophic crisis; breeding stops in winter. Females produced more than one brood per year.

Detection of new non-indigenous species is often delayed when taxonomically challenging taxa are involved, such as small-sized marine organisms. The present study highlights the relevance of scientific cooperation in the early detection of the invader amphipod Stenothoe georgiana. Originally described from North Carolina (USA), the species was recently found in Chile and the Western Mediterranean. Here, we provide the first record of the species in Macaronesia, Atlantic coasts of continental Europe, North Africa and Australia, and extend its known distribution along the Mediterranean coast. Just like other small crustaceans, shipping (including recreational boating) and aquaculture are probably the main vectors of introduction and secondary spread for this amphipod species. This case of S. georgiana sheds light on the importance of promoting taxonomical knowledge, and building multidisciplinary expertise networks that ensure an effective spread of alien species information. We also encourage the implementation of standardized monitoring methodologies to facilitate early detection of small mobile invaders.

Abstract. The authors demonstrate the probable immigration and stable settling of the pycnogonid Ammothea hilgendorfi (Böhm, 1879) at one station in the lagoon of Venice. The species is widely distributed naturally on both sides of the Pacific Ocean and has probably immigrated on ship hulls through the Suez Canal to the Mediterranean. Two more cases (the pycnogonid Anoplodactylus portus and the amphipod Elasmopus pectenicrus) of adventitious species in this sea are compared.

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