Spatio-temporal benthic biodiversity patterns and pollution pressure in three Mediterranean touristic ports.

The Mediterranean Sea is one of the busiest areas worldwide in terms of maritime activity, facing considerable anthropogenic disturbance, such as pollution by hydrocarbons and heavy metals. The present study has evaluated the environmental and benthic biodiversity characteristics of three touristic ports, Cagliari (Sardinia, Italy), Heraklion (Crete, Greece) and El Kantaoui (Tunisia), based on the combined assessment of physical parameters, chemical variables (i.e. nutrients, pigments), sediment pollution and macrobenthic biodiversity. Different port sectors (leisure, fishing, passenger, cargo, shipyard) and different seasons (winter, before touristic period, after touristic period) were compared. Salinity and sediment concentration of copper and antimony were the three environmental parameters most highly correlated with benthic species composition and diversity. Both the environmental variables and the benthic biodiversity patterns were significantly different between the three ports (i.e. different geographical locations). Heraklion port was heavily polluted by AHs in surface and anoxic sediments and had the highest percentage of opportunistic species, while Cagliari had the highest levels of PAHs and UCM and low species richness. El Kantaoui port was less polluted and characterised by a richer biodiversity. The shipyard sector in Heraklion port was significantly different from all other sectors in terms of abiotic and biotic parameters. Physico-chemical and pollution variables recorded during the period after tourism (late summer) were significantly different from the ones recorded in winter. Seasonal differences were not significant between benthic species diversity patterns, but were revealed when the patterns derived from the aggregation of higher taxonomic levels were compared. The present study indicates that a regular-basis monitoring plan including evaluation of environmental health based on benthic biodiversity, can provide a basis for perceiving changes and reveal the degree of anthropogenic disturbance in port environments.

Sandhopper orientation under natural conditions: comparing individual tracks.

The analysis of animal movements may help to understand orientation strategies. While there have been many studies on sandhoppers' orientation mechanisms through the analysis of their orientation angles, no attempts have been made to analyze individual tracks under (varying) natural conditions. The species Talitrus saltator (Montagu, 1808) has the ability to recover the optimal zone of the beach at or below the drift-line and burrow into moist sand when released in the upper beach during the day. On dry sand sandhoppers typically jump and leave tracks; we measured the tracks in relation to the starting point. For each track we calculated: the mean angle of direction, distance covered from the starting point, number of jumps, number of effective turnings, rectilinearity and efficiency (how well the track was directed to the goal). We proposed a classification of the tracks based on both rectilinearity and efficiency. Freshly collected adult individuals from the population of San Rossore beach (Pisa, Italy) were compared to laboratory-born ones so as to highlight eventual differences related to experience. Most of the wild individuals made tracks with high rectilinearity and efficiency. This good orientation suggests that these individuals had developed experience of their beach rapidly recovering the optimal zone. Laboratory-born individuals showed a higher scatter in orientation and winding tracks. The factors that influenced the individuals during their movements could also be inferred by the track course. In addition to the sun azimuth (sun compass), wind direction appeared to be a major factor influencing orientation. The individuals released with onshore winds were more efficiently oriented seawards than those released with winds from other directions.