Leonardo Favilli

A tropical fish community in thermal waters of southern Tuscany

In a small stream of southern Tuscany (Fossa Calda), fed by hot springs, we discovered a fish community dominated by tropical species, some of which have never previously been reported in Euro-Mediterranean natural freshwater environments. The aim of our research was to ascertain whether the three most abundant and widespread species (Amatitlania nigrofasciata, Hemichromis sp. and Oreochromis niloticus) have become established. Analysis of size class distribution and growth curves showed that the populations of these species are quite large and made up of juveniles, subadults and adults, as is the case in self-sustaining populations. These fishes were probably released intentionally, since they are widely used in aquariums and aquaculture and their survival in Fossa Calda was possible because of the constant high temperature of thermal waters. Spread to other streams seems unlikely. In fact, at some distance from the hot springs, where water temperatures are lower, populations of the tropical species were small.

Some abiotic factors affecting the activity and habitat choice of the tiger beetle Cephalota circumdata leonschaeferi (Cassola) (Coleoptera, Cicindelidae)∗

Abstract A total of 213 males and 234 females of the tiger‐beetle Cephalota circumdata leonschaeferi (Cassola) were individually colour marked in the three years of study (1984, 1985, 1986). The maximum number of days in which marked individuals were resighted was 37. These tiger‐beetles dispersed within a radius of 30 m from their respective marking places. Re‐sightings were rare beyond this dis tance; one individual was observed at about 100 m from its marking place. The ground temperature proved to be a key‐factor influencing the activity and viability of the population; optimal ground temperature ranged between 32–33°C as to number of individuals present, but a temperature of 34–35°C determined the greatest number of matings. A negative influence on C. c. leonschaeferi survival and activity was exerted by cloudy and, particularly, rainy weather. Wind force influenced the habitat selection: an increase of wind force generated a greater use of terrain without vegetation (Salicornia). Apparently the incr...

The effects of prey movement, size and colour in the attack/avoidance behaviour of the Tiger beetle Cephalota circumdata leonschaeferi (Cassola) (Coleoptera Cicindelidae)

An examination has been made of factors triggering attack behaviour in adult Cephalota circumdata leonschaeferi (Cassola), living in the coastal strip of the Orbetello Lagoon Nature Reserve. Coloured dummies (blue, white, brown, black, red, and green) of various sizes (3.8, 7.5, 15 and 30 mm) have been used to evaluate the role of the following stimuli: movement, size and colour. Attacks recorded with experiments carried out in absence of movement (3.83%) were markedly fewer than those in presence (57.26%) of movement. The size of bait most frequently attacked by Tiger beetles was the 7.5-mm long one (corresponding to 1/2 the size of the adult Cephalota). The largest bait (30 mm) was significantly less stimulating than the other three sizes. Red was the colour that most stimulated attack and white the least. Brown and black gave results more similar to those of red, whereas green and blue frequently displayed a significantly less stimulatory effect. The two sexes displayed differences of reaction to the b...

Role of Predators, Habitat Attributes, and Spatial Autocorrelation on the Distribution of Eggs in the Northern Spectacled Salamander (Salamandrina perspicillata)

Abstract We predicted that the probability of egg occurrence of salamander Salamandrina perspicillata depended on stream features and predation by native crayfish Austropotamobius fulcisianus and the introduced trout Salmo trutta. We assessed the presence of S. perspicillata at 54 sites within a natural reserve of southern Tuscany, Italy. Generalized linear models with binomial errors were constructed using egg presence/absence and altitude, stream mean size and slope, electrical conductivity, water pH and temperature, and a predation factor, defined according to the presence/absence of crayfish and trout. Some competing models also included an autocovariate term, which estimated how much the response variable at any one sampling point reflected response values at surrounding points. The resulting models were compared using Akaikes information criterion. Model selection led to a subset of 14 models with ΔAICc < 7 (i.e., models ranging from substantial support to considerably less support), and all but one of these included an effect of predation. Models with the autocovariate term had considerably more support than those without the term. According to multimodel inference, the presence of trout and crayfish reduced the probability of egg occurrence from a mean level of 0.90 (SE limits: 0.98–0.55) to 0.12 (SE limits: 0.34–0.04). The presence of crayfish alone had no detectable effects (SE limits: 0.86–0.39). The results suggest that introduced trout have a detrimental effect on the reproductive output of S. perspicillata and confirm the fundamental importance of distinguishing the roles of endogenous and exogenous forces that act on population distribution.