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North African coastal lagoons are unique ecosystems that often suffer degradation due to human activities. Therefore, monitoring methods are required to identify stressors and assist with the management of these valuable and often understudied ecosystems. A synthetic indicator of water ecological quality would be desirable for regular monitoring of these ecosystems under pressure. In 2008 an optical procedure was developed and applied in Ghar El Melh, a Tunisian lagoon which has been increasingly impacted by pollutant loading, especially from agriculture.In situhyperspectral irradiance was measured at several stations, from which the apparent optical properties (AOPs), namely the irradiance attenuation coefficientK(λ) and the reflectance ratioR(λ), were obtained in order to relate them to water composition, in terms of light-attenuating substances (LASs). The significant relationships observed betweenRand LAS values enabled the application of a hyperspectral optical classification, which effectively highlighted threatened sectors of the lagoon. The pattern of differing water quality across the lagoon system that was derived from the hyperspectral classification agreed well with that obtained from a conventional optical classification that included AOPs and LASs. We suggest that hyperspectral analysis and classification is a useful monitoring tool for the assessment of change in coastal lagoons, and perhaps also in other shallow-water ecosystems. [ABSTRACT FROM AUTHOR]

The amphipodTalitrus saltator(Montagu 1808), diffused on the Mediterranean and Eastern Atlantic coasts, displays physiological and behavioural adaptations to life on sandy beaches. To avoid dehydration, sandhoppers burrow in moist sand near the water’s edge during the day in the warmest seasons. When displaced, they can navigate to this safe zone using a sun compass and several additional mechanisms, both universal and local, an adaptive behaviour named ‘zonal recovery’. In this study, we analysed the effects of several variables on the talitrids’ orientation behaviour to highlight the relevance of the local cues and analyse the behavioural variation with relation to the ecology of sandy beaches. In different seasons for 2 years, orientation experiments were made onT. saltatorsub-populations, at three sites of an extended sandy beach, differing in shoreline sedimentary dynamics; the main environmental, climatic and individual variables known to influence talitrid orientation were registered during each experimental session. The statistics of circular distributions were calculated and a multiple regression analysis adapted to angular data was performed, to highlight the scaling triggered by environmental conditions. The results showed that seasonal climatic variables played a primary role, adaptively modifying the sandhoppers’ behaviour. A significant interaction with the site (the chosen sites differed for sedimentary dynamics) was observed as well. A high behavioural plasticity appears to guarantee toT. saltatora good adaptation (both as abundance and geographical spreading) to life on sandy beaches, which are notably unstable environments. [ABSTRACT FROM AUTHOR]

The behaviour of talitrids, being a local adaptation to beaches, is known to be related to environmental stability. The use of behavioural responses of resident populations as bioindicator of shoreline stability has been tested under various conditions, including after soft and hard engineering actions to stabilise eroded beaches. Port structures likely have impact on sediment longshore transportation and shoreline stability. The question was whether talitrid orientation behaviour could be proposed as bioindicator of impacts also for sandy bays of limited extension and highly used for recreation, such as those in the vicinity of touristic port structures. Orientation experiments were carried out on a set of sandy beaches of different extension and morphology, each of them in the vicinity of a touristic port, across the Mediterranean coasts. The protocol included field orientation tests of populations of talitrids, then analysed in terms of orientation precision seawards (considering sun compass orientation as the most locally adapted behavioural mechanism) in different seasons (before and after the touristic season) and times of day. The populations from more protected (either naturally or artificially) headland-bays showed a higher precision of orientation with respect to the shoreline direction than those from extended beaches, more subject to changes in longshore sedimentary transport as consequence of natural and human activities. The distance from the port and touristic pressure had no influence on talitrid orientation. An important stabilising factor for the sandy beach ecosystems, including talitrid populations and their behavioural adaptation, appeared to be the presence of seagrass banquette. The behavioural data point out that biotic information proceeding from local animal populations linked to beach sediments may complement sedimentology data and allow scaling the impacts occurring on a developed coastline. This becomes particularly relevant when considering interdisciplinary approaches to monitoring strategies. [ABSTRACT FROM AUTHOR]

Examines the timing, orientation and motivating and directing factors of the spontaneous movements of the sandhopper Talitrus saltator on a Mediterranean beach in Tuscany, Italy. Landward migration after sunset for juveniles; Effect of temperature on spontaneous movements; Description of the habitat of the sandhopper, Talitrus saltator.

The water amphipod Dikerogammarus villosus (Sowinsky, 1894) has colonised many rivers and water basins in central Europe and is rapidly reaching southern Europe. It was found in northern Italy in 2006 and in central Italy in 2008. In this last area it has colonised the recent artificial basin of Bilancino (Mugello Valley, Florence), currently being the only and abundant amphipod species in the lake. This new population offered a good opportunity to study the life cycle and behaviour of such unpopular species (called killer shrimp because of its aggression), with the aim of better understanding the mechanisms of survival and diffusion of water gammands. For about one year and a half, bimonthly samplings were carried out in different points of the lake to study the life cycle and identify the most suitable populations for behavioural experiments. On this species experiments were carried out in the natural context to verify sun and landscape orientation and in the laboratory to analyse the response to a black boundary, direct light and substrate slope. The populations from the different points had a comparable structure and development, even if subjected to variations linked to the local features of the lake's bottom. The response to the black boundary (simulating a predator or a refuge) was not significant, while a significant reaction of avoidance of a direct artificial light and a significant preference for the basin bottom (downslope) were observed. No specific responses were identified where the behaviour was strictly linked to the environment colonised (Orientation to the sun and natural landscape). A lack of fine-tuned adaptations was expected in this species that has colonised a variety of environments, confirming comparable results on the physiology of this species, such as adaptation to wide ranges of temperature, salinity and oxygen levels. [ABSTRACT FROM AUTHOR]

The sandhopper Talitrus saltator Montagu (Amphipoda) is a widespread species adapted to different changing environmental conditions and which typically shows a clear circadian rhythm of locomotor activity. The populations from two beaches on the western Italian coast differing in coastline dynamics (eroded versus dynamically stable) and human disturbance (inside a natural park versus freely used and cleaned for leisure) were studied to highlight intrapopulation variation in the endogenous locomotor rhythm. The activity of adult sandhoppers was studied under constant laboratory conditions within individual recording chambers. Variation of the free-running period was analysed at individual level within each population. Greater variability was found than previously reported for the circadian rhythm period of T. saltator, and seasonal variation was shown for the first time. Differences in the level of variation were correlated with coastline dynamics. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

In an attempt to unravel the possible relationships among coastal stability, genetic variability and orientation behaviour in the sandhopper Talitrus saltator, we have screened four subpopulations of this species. Sandhoppers along 3 km of a dynamic sand beach were studied for orientation performance (i.e. adherence to the seaward theoretical escape direction (TED)) and sequence variation for a fragment of the mitochondrial (mt) gene encoding for the cytochrome oxidase subunit I (COI). The sampling sites differed in the stability of the shoreline (from severely eroded to accreting). Analysis of molecular variance (AMOVA) revealed significant subdivisions among the four locations. The subpopulation sampled at the most eroded point showed no haplotype diversity and had the highest scatter in orientation. Genetic diversity increased with decreasing erosion. Orientation performances were best where the beach is in dynamic equilibrium, and were progressively more scattered at the accreting points. Multiple linear regression analyses demonstrated that the variables and factors that affected orientation significantly were daytime, global solar radiation, sex of individuals and haplotype diversity. Environmental factors are likely to influence sandhopper behaviour on a short and medium time scale (i.e. from single individual life span to a few generations). The data also suggest that temporal stability of the shoreline has a positive effect on the genetic variability of the resident sandhopper populations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 female's 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 g m−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 g m−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. [Copyright &y& Elsevier]

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 Fisher''s 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, Simpson''s 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. [Copyright &y& Elsevier]

Temporal and spatial distribution patterns of a population of Talitrus saltator living on the Tyrrhenian coast of Tuscany (Italy) were studied. Bimonthly surveys were performed from March 1991 to January 1992 along transects using a standard system of pitfall traps and sieves for surface-active and burrowed individuals, respectively. Captured individuals were subdivided into sex and age classes (on the basis of the number of articles of the flagellum of the second antenna). Abundances were calculated for each sampling period and sex ratios were determined. For each sampling period the mean hour of surface activity was calculated together with the mean zonation of both surface-active and burrowing sandhoppers belonging to the different sex and age classes. Shifts in mean zonation between the resting and active phase were also determined. For each category of sex, age, and reproductive phase, simple and multiple regression analyses were used to find relationships of the mean zonation of surface-active animals with climatic data, and of the number of burrowed individuals with surface sand parameters recorded in correspondence to the sieves. On the whole, the results show that this Tyrrhenian population of T. saltator exhibited a bivoltine reproductive cycle and that the sex ratios of active sandhoppers were male or female biased according to the season. The variations in the mean hour of surface activity and in the zonation patterns of sandhoppers depended more on the age than on the sex. Furthermore distribution patterns were generally related to seasonal changes in the local climatic and substrate parameters. The observed differences between burrowing and activity zonations were interpreted on the basis of the nocturnal migrations of the different categories. [ABSTRACT FROM AUTHOR]

Presents a study that examined the spatial distributions of sand beach arthropods at Zouara, a beach dune system along the northwestern coast of Tunisia. Assessment of the capture frequency of the arthropod species; Analysis of environmental parameters in the beach dune system; Differences in the seasonal distribution of the species.