Isabella Colombini

Surface activity, zonation and migrations of Talitrus saltator on a Mediterranean beach

The present study considers a population of Talitrus saltator (Montagu, 1808) living along a Mediterranean beach (Burano, Grosseto, Italy). From April 1986 to March 1987 the annual and daily patterns of amphipod activity were analysed together with zonation and the direction and extent of movements. An annual bimodal activity pattern was established with a first peak of activity in late spring and another one in autumn. Daily activity was predominantly nocturanl with two peaks, one of which could be suppressed or depressed in accordance with particular climatic conditions. The species studied was generally limited to the eu- and supralittoral part of the beach, but the extent of zonation could vary according to climate. Differences between juveniles and adults appeared both for activity patterns and for zonation. Movements were predominantly (ca. 85%) along the sea/land axis with a landward migration always followed by seaward one. Under conditions of high relative humidity and rain, the migrations towards land could extend to the dune. Movements parallel to the shoreline were demonstrated in a separate experiment (in June and October 1987 and June 1988) using the capture-mark-recapture method. The maximum distance covered registered in one night was 200 m.

Comparison of Talitrus saltator (Amphipoda, Talitridae) biology, dynamics, and secondary production in Atlantic (Portugal) and Mediterranean (Italy and Tunisia) populations

Talitrus saltator biology, population dynamics, and reproduction were studied more or less simultaneously at three sand beaches: Lavos, on the western coast of Portugal; Collelungo, on the Italian coast of the Thyrrenian Sea; and Zouara, on the northern coast of Tunisia. The species exhibited a consistent pattern of aggregated distribution. Densities were higher at Lavos than at Collelungo and Zouara. Reproduction took place from early March to late September at Lavos and Collelungo, and from late February to early November at Zouara. The average sex ratio was favourable to males at Lavos and Collelungo, and to females at Zouara. Based on data from Lavos, the population abundance was positively correlated with temperature, while the percentage of juveniles in the population was positively correlated with temperature and sediment moisture. Adult individuals from the Atlantic population were larger than the Mediterranean ones, while newborn individuals from the Mediterranean were slightly larger than Atlantic ones. Life span was estimated at 7-11 months at Lavos, 6-9 months at Collelungo, and 6-8 months at Zouara. Cohorts born at the beginning of the reproductive period tend to have shorter lives than the ones born later in the season, with longer life spans occurring in cohorts that crossed the winter to breed in the next year. The minimum period necessary for sexual differentiation after birth was estimated at ±4 weeks at Lavos, ±3 weeks at Collelungo, and ±4.5 weeks at Zouara, for males, and ±6 weeks at Lavos, and ±5 weeks at Collelungo and Zouara, for females. The period necessary for females sexual maturation after being born was estimated at ±10 weeks at Lavos, and ±8 weeks at Collelungo and Zouara. At the studied sites, T. saltator appeared as semiannual species, with iteroparous females appearing to produce at least two broods per year, and exhibited a bivoltine life cycle. Growth production (P) was estimated at 0.74 g m -2 yr -1 ash-free dry weight (AFDW; 17.7 kJ m -2 yr -1 ) at Lavos, 0.12 gm -2 yr -1 AFDW (2.8 kJ m -2 yr -1 ) at Collelungo, and 0.61 g m -2 yr -1 AFDW (14.3 kJ m -2 yr -1 ) at Zouara. Elimination production (E) was estimated at 1.40 gm -2 yr -1 AFDW (33.5 kJ m -2 yr -1 ) at Lavos, 0.20 g m -2 yr -1 AFDW (4.8 kJ m -2 yr -1 ) at Collelungo, and 1.11 g m -2 yr -1 AFDW (26.6 kJ m -2 yr -1 ) at Zouara. The average annual biomass (B) (standing stock) was estimated at 0.13 g m -2 at Lavos, 0.014 g m -2 at Collelungo, and 0.084 g m -2 at Zouara, resulting in P/B ratios of 5.7 at Lavos, 8.2 at Collelungo, and 7.3 at Zouara, and E/B ratios of 10.8 at Lavos, 14.4 at Collelungo, and 13.1 at Zouara. The present results, combined with information from literature, revealed a geographic variation in T. saltator populations with regard to their morphological characteristics, growth rates, life spans, and life cycles.

Multiple regression analysis of the sources of variation in orientation of two sympatric sandhoppers, Talitrus saltator and Talorchestia brito, from an exposed Mediterranean beach

Abstract. Two sympatric species from an exposed sandy beach in north-western Tunisia, the sandhoppers Talitrus saltator (Montagu) and Talorchestia brito Stebbing, were compared as regards orientation under natural conditions. Sets of experiments were carried out on the beach using two experimental arenas, one permitting the view of both the sky and landscape and the other of the sky only. Replicates were made at different hours of the day, in different days and period of the year and with various climatic conditions. Multiple regression models were fitted to the angular data obtained. These models allow an estimate of the trends of variation depending on a combination of factors. The simultaneous effects of environmental factors influencing orientation were quantified for each species. The sun was confirmed as the major orientation cue in these populations, but the concentration of directional choices was enhanced by the landscape vision. The climatic factors affected orientation in different ways depending on the time of day and year. When the two species were compared, Talitrus saltator showed a higher flexibility of response than Talorchestia brito under the same environmental conditions, supporting the hypothesis of a higher level of terrestrialization of the former species.

Environmental factors influencing the surface activity and zonation of Tylos europaeus (Crustacea: Oniscidea) on a Tyrrhenian sandy beach

The present study considers a population of Tylos europaeus Arcangeli, 1938 living on a Tyrrhenian sandy beach (Burano, GR, Italy). Monthly surveys were carried out between April 1986 and March 1987 with directional pitfall traps so as to intercept the isopods moving in four directions on the beach surface. In addition a bimonthly study was performed from March 1991 to January 1992 using two methods of capture: pitfall traps joined by 10-cm high strips of fibreglas for surface-active individuals and sieving for those burrowed in the sand. Capture frequencies allowed analysis of annual abundance, daily activity and zonation of juveniles and male and female adults. Variations of these spatio-temporal data were correlated by means of multiple regression with many environmental parameters: temperature and relative humidity of the air and sand, evaporation, wind direction and speed, global radiation, atmospheric pressure, rainfall, the sand salinity and granulometric parameters. T. europaeus was found to be mainly active in summer and autumn and during the night, and was zoned along the eulittoral. The surface activity was influenced by almost all the environmental factors when they were limiting but especially by the relative humidity of the air. The mean zonation of active specimens, however, varied hourly according to the sand temperature. On the other hand, the zonation of the buried individuals depended on the mean grain size, which involves many other parameters, such as moisture and oxygen contents.

Comparative diversity analysis in sandy littoral ecosystems of the western Mediterranean

Abstract A comparative faunal analysis was carried out in sandy littoral localities differing both morphologically and in human impact. The study sites were located in the western Mediterranean basin along the coasts of Morocco, Tunisia, the Maltese Islands and Italy. These were typical beach–dune ecosystems more (Smir, Morocco; Zouara, Tunisia; Burano, Italy) or less (Ir-Ramla tat-Torri, Malta and Ir-Ramla l-Hamra, Gozo) structurally developed accordingly. Species richness was evaluated using standard trapping techniques with pitfall traps along the transects perpendicular to the shoreline. Only isopods and coleopterans were used in the analysis. In each locality, an analysis was conducted on both the beach and the dune separately, and on the entire ecosystem in the two seasons (spring and autumn). Species were studied both quantitatively and qualitatively using ecological coefficients (relative abundance) and Fishers diversity index. To evaluate the evenness of the community, Shannon–Weaver index was calculated and compared with Brillouin index. For both indices, the maximum values were computed and were used to obtain the evenness of the community through Pielou index. In addition, Simpsons dominance index was considered. Percentages of similarities between localities were analysed in the two seasons and in total using the Renkonen index. The overall analysis showed that general trends could be found for both orders that were studied and gave indications on habitat quality. The study showed that when monitoring was carried out systematically both in space and time, arthropods could be used as important tool to assess beach health.

Spatial and temporal strategies in the surface activity of some sandy beach arthropods living along the French Atlantic Coast

During a field study on the eco-ethology of sandy beach arthropods conducted along the French Atlantic Coast it emerged thatTylos europaeus, Phaleria cadaverina andLabidura riparia were among the most abundant species that lived in the eulittoral. Tetradirectional pitfall traps, placed from the base of the dune to the tidal limits, were used. The traps intercepted surface-active arthropods, and the number of traps varied according to the levels of the tides. Data were recorded hourly during two periods corresponding to a spring tide and the following neap tide. At the saine time the most important environmental parameters were registered each hour. The results indicate that all three species show prevalently nocturnal surface activities. ForT. europaeus andPh. cadaverina an influence of the synodic and tidal phases was found on the zonation of the surface activity and on the extent of movement. The latter was due to the greater or smaller distances that the isopods and tenebrionids had to move from the diurnal burrowing sites to the foraging zones. ForL. riparia no variations in the total mean zonations were found between the two synodic phases, and only at neap tide were seaward, followed by landward movements found. Multiple regression analysis showed that the environmental parameters registered in this period were never limiting, as threshold values in this case probably were not reached.

Terrestrial Macroinvertebrates as Key Elements for Sustainable Beach Management

ABSTRACT COLOMBINI, I., FALLACI, M and CHELAZZI, L., 2011. Terrestrial Macroinvertibrates as Key Elements for Sustainable Beach Management. In: Micallef, A. (ed.), MCRR3-2010 Conference Proceedings, Journal of Coastal Research, Special Issue, No. 61, pp. 24–35. Grosseto, Tuscany, Italy, ISSN 0749-0208. Recreational activities on sandy beaches are basically human centred and there is little concern of their biological components. Terrestrial sandy shore are often regarded as void boxes of sand to be reconstructed where missing, decorated with coastal vegetation and mechanically cleaned for aesthetic and sanitary reasons. But what costs, in terms of biodiversity loss, are we dealing with? Can beach management be sustainable without considering the fact that terrestrial beach macroinvertebrates are hardly taken into account in management practices? Do beach managers know the importance of terrestrial macroinvertebrates for ecosystem functioning? What measures are needed to avoid the massive loss of species? To address these questions a ten year period of study was conducted on the beach of the Maremma Regional Park (Grosseto, Italy). Here direct impacts due to human activities (beach recreation, trampling, etc) were relatively low, but indirect ones (a severe problem of beach erosion at the Ombrone river mouth) were taking place and large sections of the beach had already been destroyed. Since one of the main attractions of the Maremma Regional Park was the beauty of its beaches (used for summer bathing activities), concerns of the public opinion and of park managers were extremely high. A first approach of our study was to evaluated the health of the beach environment through a baseline ecological study and to pin pointed the main factors causing the erosion process. The study showed that the system was in a dynamic equilibrium with an erosion process going on one side and a accretion process on the other. Biodiversity levels followed linear gradients with increasing levels at increasing distance from the river mouth and were related to increases in habitat complexity. Changes rapidly occurring around the river mouth had produced a shift of the macroinvertebrate community in a buffer area at a higher distance from the river mouth where populations were still consistent in species number and abundance. Furthermore, studying beach populations at increasing distances from the river mouth on a monthly basis demonstrated that terrestrial beach invertebrates (amphipods, isopods, tenebrionids), strictly inhabiting the sand, tended to shift horizontally along the beach to avoid human disturbance according to the season. This finding not only has an ecological importance for the resilience of the ecosystem, showing the value of buffer areas as resources for biodiversity, but also it presents practical aspects as it can be used by beach managers to plan actions for sustainable management. In other beaches where impacts are high this tool could be employed to fine tune spatial and temporal beach cleaning events to avoid further losses of beach species and/or the recovery of others. The study, however, suggests the need of an active interaction between scientists, stakeholders and managers. Communication is also needed between beach ecologists and coastal recreational managers to whom this conference is addressed as more often it has occurred that defence measures have been taken without considering the impacts on the biotic components of the beach ecosystem.

Solar and landscape cues as orientation mechanisms in the beach-dwelling beetle Eurynebria complanata (Coleoptera, Carabidae)

The present paper reports on the first orientation experiments conducted on the strand-living beetle Eurynebria complanata (Linnaeus, 1767) (Coleoptera, Carabidae). The experiments were carried out from June to October 1988. Two different populations were used: one inhabiting a Tyrrhenian beach in Italy and the other a beach on the Atlantic coast of France. Response to sun compass cues was demonstrated in each population at the collection site and for the French population after transportation to Italy, where experiments were carried out on a differently oriented beach. Landscape cues were shown to improve the beetles orientation capacity when these were tested together with a visible sun. Artificial landscapes were also tested under laboratory conditions. Different-sized silhouettes were placed in the four cardinal directions, and these envoked different responses depending on their height. The beetles oriented towards a black silhouette when this subtended an angle of 25°. The results obtained for the two populations are compared and discussed from an eco-ethological point of view.

Enzyme activity and trophic links of macroarthropods living on an exposed Mediterranean beach–dune system

Abstract Arthropod communities of beach–dune systems are mainly composed by detritivorous species, apparently with overlapping trophic niches. This study aims at distinguishing the trophic roles of sympatric species, by using a biochemical approach in the analysis of gut contents. The digestion of seven trisaccharidic and disaccharidic substrates containing the glycosidic bond was tested in gut homogenates of 10 species of detritivorous insects and crustaceans from a Mediterranean beach–dune system (Tuscany, Italy). Glycosidase activities were compared between species. A dendrogram was determined separating species with different enzymatic activity spectra. The differences observed in the enzymatic activities may be related to a different use of the available food resources and interpreted as an opportunist nutrition of arthropod species sharing the same habitat.

Evaluating impact of possible transgenic poplar cultivation on protected areas

Background Plant biodiversity studies have been performed in the Migliarino-San Rossore-Massaciuccoli Regional Park in Tuscany (Italy) within the framework of the European project LIFE08 NAT/IT/342.This project aims at developing a quick monitoring index (QMI) to rapidly assess the potential risk generated by transgenic plants in characterized ecosystems or biotopes. For this reason test areas have been selected inside the protected area to evaluate plant (weeds and trees), animal, and soil microoganisms biodiversity. The proximity of the selected test area to cropped surfaces where Genetically Modified Plants (GMPs) might be cultivated has been taken into account. GMPs could spread pollen and contaminate natural populations. To avoid this risk, an efficient monitoring system is required taking into account genetic diversity and breeding study. As far as tree biodiversity concern, Populus species were identified in the test areas. Two populations of Populus present into two different ecosystems (forest and wetland areas) were examined together with two cultivated varieties. The two ecosystems were characterized for the vegetation. Nuclear microsatellites were used to evaluate genetic diversity of poplar populations and level of breeding between natural and cultivated Populus. In addition the insect populations present on male and female poplars during flowering period have been studied.