Shipping traffic and introduction of non-indigenous organisms : Study case in two Italian harbours
In order to study the role of ballast water in introducing non-indigenous organisms in the Mediterranean Sea, the maritime traffic was analysed in the harbours of Naples and Salerno, which are important commercial ports in southern Italy. The 2001 data concerning the number of ships, the cruises’ length and the source of arrivals, were taken from harbours’ offices logbooks. In both harbours, the Mediterranean traffic was higher compared to the world sea-borne traffic that was mainly coming from North East Atlantic countries. The mean length of travels was of 1 week while the longest voyages were from Australia (3 weeks). A theoretical amount of ballast waters discharged during 1 year was provided by using an European model. A total of 55,738 and 118,339 ton of foreign ballast water are released annually in Naples and Salerno, respectively, to which theoretically correspond the entry of 4,977,403 (Naples) and 10,366,496 (Salerno) phytoplanktonic specimens.
Intraspecific genetic lineages of a marine mussel show behavioural divergence and spatial segregation over a tropical/subtropical biogeographic transition
BackgroundIntraspecific variability is seen as a central component of biodiversity. We investigated genetic differentiation, contemporary patterns of demographic connectivity and intraspecific variation of adaptive behavioural traits in two lineages of an intertidal mussel (Perna perna) across a tropical/subtropical biogeographic transition.ResultsMicrosatellite analyses revealed clear genetic differentiation between western (temperate) and eastern (subtropical/tropical) populations, confirming divergence previously detected with mitochondrial (COI) and nuclear (ITS) markers.Gene flow between regions was predominantly east-to-west and was only moderate, with higher heterozygote deficiency where the two lineages co-occur. This can be explained by differential selection and/or oceanographic dynamics acting as a barrier to larval dispersal.Common garden experiments showed that gaping (periodic closure and opening of the shell) and attachment to the substratum differed significantly between the two lineages. Western individuals gaped more and attached less strongly to the substratum than eastern ones.ConclusionsThese behavioural differences are consistent with the geographic and intertidal distributions of each lineage along sharp environmental clines, indicating their strong adaptive significance. We highlight the functional role of diversity below the species level in evolutionary trends and the need to understand this when predicting biodiversity responses to environmental change.
A critical survey of the marine algae of Southern Australia. II. Phaeophyta
A survey is given of the known Phaeophyta of southern Australia, including synonomy, references, type data, and critical notes. The following new taxa are described: Sphacelaria carpoglossi, Distromium flabellaturn, and D. multifidum. Many names are reduced to synonomy and earlier specific names used in a number of cases. The southern Australian Phaeophyta include nearly 200 recognized species, and several minute taxa remain undescribed. Noteworthy orders are the Sphacelariales (4 genera and 23 species), Dictyotales (13 genera and 41 species), Sporochnales (6 genera and 11 species), and Fucales (16 genera and some 69 species).