Simone Gambineri

Orientation of littoral amphipods in two sandy beaches of Brittany (France) with wide tidal excursions

Sandhoppers orient towards the shoreline using a sun compass when they are subject to dry conditions. In this study we analysed the orientation of populations from two sandy beaches with wide tidal excursions (Brittany, France): at Damgan (sea to the South) and at Le Verger (sea to the North). At Le Verger beach Talitrus saltator was found together with Deshayesorchestia deshayesii (former Talorchestia deshayesii). The results of the experiments on sun and landscape orientation showed that the Damgan T. saltator oriented better with ebbing tides than with rising tides, while the Le Verger T. saltator showed the opposite trend as a response to tides. This is probably related to the differing risk of being swept away by tides at the two localities. D. deshayesii was found to be more scattered in orientation than T. saltator, probably because it is a recent colonizer of that beach.

The eyes of two talitrid amphipods: differences in structure may reflect different behaviours

In this study, compound eyes of two species of talitrid amphipods–Talorchestia spinifera from Asilah (Atlantic coast of Morocco) and Talitrus saltator from Oued Laou (Mediterranean coast of Morocco), Maremma Regional Park and Palizzi Marina (Tyrrhenian and Ionic coasts of Italy)–were compared. Both T. spinifera and T. saltator possess compound apposition eyes, with ommatidia separated by a connective coating which is thicker in T. spinifera and incomplete in T. saltator. The lenses of each ommatidium are crossed by a vesicular structure (previously undescribed) that differs between the two species for its whole orientation across the eye. This different arrangement of the structure in the two species suggests a number of specific adaptations to their visual habitats. These adaptations are discussed.

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.

Deconstructing responses of sandy beach arthropodofauna to shoreline erosion: looking for the proper spatial scale to monitor biodiversity

The suitability of the small spatial scale of sandy beaches was tested as unit for monitoring biodiversity. The study targeted a coastal stretch in central Mediterranean, characterised by a patchy landscape and erosion trend. Beach arthropod communities (abundance, biodiversity and behavioural adaptation) were considered in the context of ongoing changes and threats to beach habitats. Nine beach units were selected as part of three main coast sectors, each with a different exposure. Beach units were sampled for arthropod diversity, which was assessed at different levels of organisation: taxa abundance, diversity indices and behavioural adaptation. These features were used as response variables in models considering beach physical factors. Sand grain size, swash extent and beach slope resulted the driving forces for abundance and diversity. Behavioural tests indicated a local adaptation to the shoreline direction, with mean angles of orientation seawards. Data related to biodiversity assessment were applied to the estimate of Conservation and Recreation Indices (CI and RI). Coast sectors subject to different erosion rates scored differently, pointing to a potential conflict in management of beaches subject to physical erosion. Overall, data depicted beach sectors, each one including one or more beach units, as the most suitable dimension for deconstruction to the small-spatial scale. The selection of the scale for deconstruction, applicable to geomorphological, biological and managerial contexts, would be of paramount importance to guide decision-making and compare coastal stretches also in other geographic contexts.

Monitoring changes in sandy beaches in temperate areas through sandhoppers' adaptations

Sandhoppers (Amphipoda, Talitridae) are keystone species of sandy beach ecosystems in temperate areas. Several traits have been studied and proposed as bioindicators of impacts on sandy beaches, at individual (physiology and behaviour), population (life cycle, abundance, population dynamics and structure, morphometry and fluctuating asymmetry) and species (genetic structure and variation) levels. Sandy beaches, where these species spend their whole life cycle, are dynamic environments, subject to periodic changes (night-day, tides and seasons), as well as to impacts that may cause erosion or accretion of the littoral zone. The first response of an animal to potentially injuring factors is shown by its avoidance behaviour regarding the potential stress. This behaviour may be a rapid escape reaction, shown by single individuals, the whole or part of the population. Activity rhythms, changes in zonation, burrowing, escape reactions, orientation towards the optimal zone on the beach, are all adaptations to environmental changes, increasing the survival chances of the individuals and populations that express such behaviours. In this paper we present case studies of the talitrid species’ behavioural adaptations related to natural and human impacts on sandy beaches in the Mediterranean: (1) erosion/accretion dynamics of a Tyrrhenian beach in central Italy (Maremma Regional Park), and (2) increasing urbanisation on a beach in north-western Morocco (Oued Laou river mouth). The best behavioural adaptation was shown by the populations from more stable coastlines. For the survival value of rapid and possibly anticipatory responses to stressful factors, behavioural variation may be proposed as an early-warning indicator of environmental changes. The adaptation at higher levels (population and species) may reflect, on the one hand, the evolvability of the species and, on the other hand, the changeability of the environment. Adaptations at population level may be used as bioindicators of past changes over generations and evolutionary times.