Fluoride Concentration in Drinking Water in The Province of Soria (Central Spain) and Caries in Children

The fluoride content in the water supply of the Soria province is not normally above 0.2mg L^–1 and its geographical distribution is related to the lithological and geological features of the zone, the highest concentration being associated with the Miocene clay formation of the Almazán Basin.A statistical analysis confirms a connection between this fluoride content and tooth decay among children in rural areas. However, other factors such as oral hygiene and diet have been found to affect tooth decay.     

Density,size structure and aspergillosis prevalence in <Emphasis Type="Italic">Gorgonia ventalina</Emphasis> at six localities in Puerto Rico

Gorgonia ventalina’s density, size structure and lesion prevalence was measured at six sites in Puerto Rico that exhibited variation in horizontal water transparency, sedimentation rates, suspended particle matter, scleractinian and macroalgal cover. G. ventalina density varied significantly among sites (between 0.84 and 0.007 colonies/m²), and was positively correlated with water transparency. Size structure did not vary much among sites, and reflects high mortality among the smaller size classes and high survivorship in large colonies. Prevalence of active fungi-induced lesions (type I) did not vary significantly among sites and was density-independent. However, prevalence of old lesions of unknown origin (type II) did vary among reefs and was negatively correlated with water transparency. Prevalence of types I or II lesions was independent of colony size. Our results suggest that (1) turbidity and sedimentation are important abiotic factors controlling the abundance of sea fans, (2) variation in settlement success and early survivorship of recruits has more impact on the sea fan populations than variation in the survivorship of large colonies and (3) prevalence of aspergillosis (type I) at the studied sites is similar to that reported for other Caribbean reefs and supports the epizootic nature of the disease and (4) lesions with exposed skeleton are more likely to be colonized by fouling organisms at impacted reefs. The combined effects of anthropogenic impacts and aspergillosis may cause local extinctions of sea fans, as is becoming evident in many reefs in Puerto Rico.     

Landscape-level thresholds, and newt conservation.

Ecological thresholds are defined as points or zones at which a rapid change occurs from one ecological condition to another. The existence of thresholds in species-habitat relationships has important implications for management, but the lack of concordance across studies and the wide range of methods used make generalizations difficult. We used two different statistical methods to test for the existence of thresholds for both individual species and the whole community, using three newt species as models. Based on a sample of 371 ponds, we found significant thresholds for both landscape configuration and composition. These were for the relationships between distance to forest and occurrence of Triturus alpestris and T. helveticus, and forest and crop cover and T. helveticus. Variability in the location of thresholds observed for the different species in this study caution against their use at the community level. Future studies should be based on the identification and assessment of thresholds for targeted species. Thresholds can be a useful concept from which tools may be developed to focus conservation effort for threatened species and their habitats.     

Population structure and genetic diversity in green turtles nesting at Tortuguero,Costa Rica,based on mitochondrial DNA control region sequences

The green turtle (Chelonia mydas) nesting population at Tortuguero, Costa Rica, is the largest nesting aggregation in the Atlantic, by at least an order of magnitude. Previous mitochondrial DNA (mtDNA) surveys based on limited sampling (n = 41) indicated low genetic diversity and low gene flow with other Caribbean nesting colonies. Furthermore, a survey of nuclear DNA diversity invoked the possibility of substructure within the Tortuguero rookery. To evaluate these characteristics, mtDNA control region sequences were determined for green turtles nesting at Tortuguero in 2001 (n = 157) and 2002 (n = 235). The increased sample revealed three additional haplotypes; five haplotypes are now known for Tortuguero female green turtles. Analyses of molecular variance indicated that there was no significant spatial population structure along the 30-km nesting beach. In addition, no temporal population structure was detected either between the two nesting seasons or within the nesting season. As a result of the larger sample size and additional haplotypes, estimates of genetic separation among Caribbean nesting colonies have changed and the concordance of phylogenetic and phylogeographic patterns reported in the past for green turtles in the Greater Caribbean has weakened. The five haplotypes from Tortuguero represent 36% of the haplotypes identified in green turtle nesting aggregations in the Greater Caribbean and 17% of the haplotypes known to occur in nesting or foraging aggregations in the Greater Caribbean. Haplotype diversity (0.16) and nucleotide diversity (0.0034) for the Tortuguero population are substantially lower than those for the combined rookeries in the Greater Caribbean (0.44 and 0.0078, respectively). Although comprehensive evaluation of regional genetic diversity requires nuclear DNA data, our study indicates that conserving genetic diversity in Caribbean green turtles will require careful management of the smaller rookeries in addition to the Tortuguero rookery.     

Transmission,plasticity and the molecular identification of cyanobacterial symbionts in the Red Sea sponge <Emphasis Type="Italic">Diacarnus erythraenus</Emphasis>

Cyanobacterial symbionts in the sponge Diacarnus erythraenus from the Red Sea were identified in both adult sponges and their larvae by 16S rDNA sequencing. A single cyanobacterial type was found in all samples. This cyanobacterial type is closely related to other sponge cyanobacterial symbionts. The cyanobacterial rDNA, together with the morphological analysis by electron and fluorescence microscopy, provided evidence for vertical transmission of the symbionts in this sponge. In addition, we show phenotypic plasticity of the symbionts inside the sponge, probably as a result of variability in light availability inside the sponge tissue. Finally, the reproduction of Diacarnus erythraenus is also described.Matan Oren, Laura Steindler have contributed equally to the work.     

Effect of disturbance on foraging: whelk activity on wave-exposed rocky shores with minimal tidal range

For slow-moving rocky intertidal predators such as whelks, frequent stress can be detrimental. Most studies on the foraging behavior of whelks have been conducted in regions where tidal amplitude is >1 m and on relatively small species. We studied the effects of wave action, desiccation, and water temperature on the foraging behavior of a large (approximately 80 mm) rocky shore whelk, Stramonita haemastoma, at the small-tide (<40 cm) but wave-exposed Israeli Mediterranean coast. We hypothesized that in such conditions foraging activity of this large predator will be greatly limited. Field observations show that when wave height exceeds 0.5 m, activity of whelks decreases by at least threefold relative to that seen under calm-sea conditions, and most whelks remain inside shelters. Wave height data from offshore moorings demonstrate that such conditions occur along the coast >85% of the time. Whelks move into shelters or completely disappear when exposed to prolonged desiccation conditions that can last for days along the shore during spring and autumn. Foraging activity is greater at night than in daytime and might be related to lighter winds and calmer sea conditions at night. Laboratory experiments show that elevated water temperatures during winter do not result in increased predation rates relative to those measured during spring. This indicates that a seasonal endogenous biological rhythm may exist. Our findings demonstrate that the foraging activity of large whelks can be extremely constrained by high rates of disturbance, that is, frequent wave action, and less frequent desiccation. We claim that high rates of disturbance in the eastern Mediterranean explain why large whelks are scarce in intertidal habitats where food is plentiful but suitable shelter is rare.Communicated by G.F. Humphrey, Sydney     

Nematocyst complements of nudibranchs in the genus <Emphasis Type="Italic">Flabellina</Emphasis> in the Gulf of Maine and the effect of diet manipulations on the cnidom of <Emphasis Type="Italic">Flabellina verrucosa</Emphasis>

Aeolid nudibranchs maintain functional nematocysts, which are sequestered from the nudibranchs’ cnidarian prey and provide protection against predators. Some species exhibit extensive variation in incorporated nematocysts, while others maintain a limited number of types. This study examines the apparent diversity in uptake and patterns of nematocyst incorporation among related species. Nematocyst complements were described for four Gulf of Maine nudibranch species in the genus Flabellina exhibiting a variety of feeding strategies and prey specificities. Diet manipulations were performed to examine the response to changing nematocyst availability using a generalist consumer, Flabellina verrucosa, to assess nematocyst uptake based on diet. The flabellinid species examined exhibited significant differences in nematocyst incorporation, reflecting differences in their specificity as predators and nematocyst types available in their natural prey. The nematocyst complement of F. verrucosa was the most variable and differed among collection regions. When diet was manipulated, nematocyst uptake depended on the prey the nudibranchs consumed, but when offered a variety of prey, F. verrucosa selectively preferred nematocysts from scyphistomae. The observed variation in nematocyst uptake among species and regions probably relates to environmental disparities among populations.     

Estimating the complexity of bird song by using capture-recapture approaches from community ecology

Repertoire size, the number of unique song or syllable types in the repertoire, is a widely used measure of song complexity in birds, but it is difficult to calculate this exactly in species with large repertoires. A new method of repertoire size estimation applies species richness estimation procedures from community ecology, but such capture-recapture approaches have not been much tested. Here, we establish standardized sampling schemes and estimation procedures using capture-recapture models for syllable repertoires from 18 bird species, and suggest how these may be used to tackle problems of repertoire estimation. Different models, with different assumptions regarding the heterogeneity of the use of syllable types, performed best for different species with different song organizations. For most species, models assuming heterogeneous probability of occurrence of syllables (so-called detection probability) were selected due to the presence of both rare and frequent syllables. Capture-recapture estimates of syllable repertoire size from our small sample did not differ significantly from previous estimates using larger samples of count data. However, the enumeration of syllables in 15 songs yielded significantly lower estimates than previous reports. Hence, heterogeneity in detection probability of syllables should be addressed when estimating repertoire size. This is neglected using simple enumeration procedures, but is taken into account when repertoire size is estimated by appropriate capture-recapture models adjusted for species-specific song organization characteristics. We suggest that such approaches, in combination with standardized sampling, should be applied in species with potentially large repertoire size. On the other hand, in species with small repertoire size and homogenous syllable usage, enumerations may be satisfactory. Although researchers often use repertoire size as a measure of song complexity, listeners to songs are unlikely to count entire repertoires and they may rely on other cues, such as syllable detection probability.Communicated by A. Cockburn