Dipartimentio Biologia

Ant (Hymenoptera: Formicidae) assemblages were sampled with pitfall traps in three different habitats associated with a rehabilitated mine district and in undisturbed forests in Tuscany, Italy. The four habitats were (1) open fields (3–4 years old); (2) a middle-age mixed plantation (10 years); (3) an old-age mixed plantation (20 years); and (4) an oak woodland (40 years) not directly affected by mining activities. The aim of the study was to analyze ant recolonization patterns in order to provide insights on the use of Mediterranean ant fauna as indicators of restoration processes. Species richness and diversity were not significantly different among the four habitats. However, multivariate analyses showed that the assemblages in the different habitats were clearly differentiated, with similarity relationships reflecting a successional gradient among rehabilitated sites. The observed patterns of functional group changes along the gradient broadly accord with those of previous studies in other biogeographic regions. These were (1) a decrease of dominant Dolichoderinae and opportunists; (2) an increase in the proportion of cold-climate specialists; and (3) the appearance of the Cryptic species in the oldest plantations, with a maximum of abundance in the woodland. In conclusion, the results of our study supported the use of Mediterranean ants as a suitable tool for biomonitoring of restoration processes, and in particular, the functional group approach proved a valuable framework to better interpret local trends in terms of global ecological patterns. Further research is, however, needed in order to obtain a reliable classification of Mediterranean ant functional groups.

Patella vulgata is one of the most common limpet species on rocky shores throughout the north-eastern Atlantic. Foraging activity of this species has been described during various different diel and tidal phases and several factors have been suggested that might influence the timing of its activity. Among these, inclination of rock surfaces seems to have a clear role, with limpets on horizontal rocks being active during daylight at high water, while limpets on vertical rocks were active during night-time low water. However, by comparing the results of previous investigations it is difficult to separate clearly the effect of any single factor from the effects of their interactions. In the present paper we investigated the simultaneous influence of height on the shore, slope of rock surface and date of sampling (August–September and March–April) on the behaviour of a population of P. vulgata on the Isle of Man (UK). The study was carried out using modern telemetric methods, allowing the activity patterns of limpets to be recorded for long periods of time. The results showed that limpets concentrated their activity during two distinct temporal windows—daytime tide-in and night-time tide-out—while no significant activity was observed during daytime tide-out or night-time tide-in. The observed behaviour appeared to be driven by complex interactions among the three factors examined, and the influence of rock slope alone was not so strong as to override the effect of other factors completely. In addition, a key finding of this study was the conspicuous variability in the individual behaviour of P. vulgata. The greatest level of variability was observed in limpets on vertical surfaces on the upper shore, which showed an extreme switch in behavioural patterns, according to date of sampling (daylight/tide-in foraging during the spring and night-time/tide-out foraging during late summer). In addition, individuals apparently sharing the same set of conditions (inclination, height on the shore and sampling date) differed in their behaviour, and a given behavioural pattern was not always shared by all individuals from a given group. Finally, variability was also observed at the ‘intra-individual’ level since the same individual could be active during different tidal and diel phases. In conclusion, although the existence of endogenous rhythms has previously been demonstrated in this species, our data clearly show that P. vulgata was able to modulate its behavioural patterns in relation to a variety of exogenous determinants.

Cardiac activity of two Mediterranean limpets was tested at different salinities. Patella caerulea inhabits the lower midlittoral where it is exposed to variations in salinity, while P. aspera experiences more stable salinity conditions in the infralittoral fringe. When exposed to moderate hypo- and hypersalinity (23 g l−1 and 43 g l−1) for 24 min, P. caerulea showed no significant variation in heart rate with respect to the control salinity (33 g l−1), while P. aspera exhibited a significant increase in heart rate in both conditions. This suggests a rise in metabolic rate due to activation of behavioural responses or physiological regulation. When exposed to extremely low salinity (3 g l−1) for 24 min, heart contractions ceased in most specimens of P. caerulea. A smaller number of specimens also displayed cessation of heart beat when exposed to extremely high salinity (63 g l−1). The heart beat resumed quickly in all specimens when they were returned to control salinity conditions. In contrast, cardiac activity was not interrupted in any of the P. aspera specimens at the 3 g l−1 and 63 g l−1 salinity levels, but strong bradycardia was evident. Contractile activity of the heart ceased in all specimens of P. caerulea and P. aspera when they were exposed to prolonged hypo-osmotic stress (3 g l−1 for 24 h). This acardia was largely reversible in P. caerulea, but most specimens of P. aspera did not recover from the treatment.

A multi-factorial experiment was designed to investigate the effect of the following factors on the cardiac activity of the intertidal crab Pachygrapsus marmoratus: respiratory medium (air, water), temperature (four levels, 10, 17.5, 25, 32.5 °C), season (winter, summer) and body size (two levels, carapace ≤21 mm and carapace >21 mm). The results showed that the heart rate of P. marmoratus increased linearly with temperature and decreased when the specimens were exposed to air rather than water. Moreover, the heart rate values in summer were lower than those in winter at the corresponding temperature and body size. The summer heart rate–temperature regression line was laterally (to the right) shifted with respect to the winter line, suggesting a seasonal acclimation. Body size affected heart rate only at the acclimation temperature (17.5 °C), while no significant effect was detected at lower or higher temperatures. During the reproductive season a separate experiment was carried out to assess the effect of sex and reproductive status on heart rate. No significant difference was found among mean values of males, berried females and females without eggs. The results of the present study confirm the high physiological plasticity of this species, suggesting that P. marmoratus is a truly amphibious crab, able to deal with both water- and air-breathing during its activity.

Dragonflies are commonly used as indicators of environmental quality and different methods have been employed to monitor odonate assemblages, such as surveys of all adults, evaluations based on breeding adults, sampling of larvae and collection of exuviae. Results obtained with different sampling methods may not be interchangeable, as the different life stages (e.g. larvae, adults) differ in mobility (aquatic, aerial) and as they are subjected to different ecological constraints. Therefore generalization about habitat quality based on only one survey method might be questionable. Additionally, detectability of species might vary when different methods are used. In this study, nine retrodunal ponds in the Migliarino, San Rossore, Massaciuccoli Regional Park (Tuscany, Italy) were repeatedly and contemporaneously sampled during May–September 2008 with the following methods: all adults, breeding adults, larvae and exuviae. In total, 22 species were detected and the results showed that the four methods were not interchangeable. First, some species were only found using certain methods. Second, univariate measures of diversity obtained with the four sampling methods were considerably different. Alpha diversity was maximal when computed on all adults and minimal with exuviae; breeding adults and larval collection had intermediate values. Beta diversity showed an inverse trend, with the lowest value for “all adults” surveys and higher values for all the others. Finally, congruence among the assemblages revealed by the four methods was generally low. The results show that the four survey techniques are not interchangeable and that monitoring of Odonata has to be based on a carefully chosen method, which should reflect the aim of the study.

The behaviour of intertidal consumers is often tightly constrained to tidal movements, although activity patterns can vary within these constraints. Spatio-temporal variability in behaviour of a limpet, Cellana grata, was analysed over different tidal conditions ...

Time series analysis plays an important role in the detection of mechanisms that drive population fluctuations. However, long time series are rare, with ungulate data sets usually not exceeding 50 years. In this article, we describe a long-term data set of population density indices of ...