Robin Snape

Turtle mating patterns buffer against disruptive effects of climate change

For organisms with temperature-dependent sex determination (TSD), skewed offspring sex ratios are common. However, climate warming poses the unique threat of producing extreme sex ratio biases that could ultimately lead to population extinctions. In marine turtles, highly female-skewed hatchling sex ratios already occur and predicted increases in global temperatures are expected to exacerbate this trend, unless species can adapt. However, it is not known whether offspring sex ratios persist into adulthood, or whether variation in male mating success intensifies the impact of a shortage of males on effective population size. Here, we use parentage analysis to show that in a rookery of the endangered green turtle (Chelonia mydas), despite an offspring sex ratio of 95 per cent females, there were at least 1.4 reproductive males to every breeding female. Our results suggest that male reproductive intervals may be shorter than the 2–4 years typical for females, and/or that males move between aggregations of receptive females, an inference supported by our satellite tracking, which shows that male turtles may visit multiple rookeries. We suggest that male mating patterns have the potential to buffer the disruptive effects of climate change on marine turtle populations, many of which are already seriously threatened.

Strand Monitoring and Anthropological Surveys Provide Insight into Marine Turtle Bycatch in Small-Scale Fisheries of the Eastern Mediterranean

Abstract It has become widely recognized that a large gap exists in the global knowledge of fisheries due to the continued oversight of the small-scale sector. For populations of marine turtles restricted to the eastern Mediterranean, bycatch in small-scale fisheries is a concern. By using North Cyprus as a case study for the region, we used anthropological methods to estimate the magnitude of marine turtle bycatch, while presenting novel information on the marine turtle life stages using the coast and profiling the fishery itself. Our analyses suggest that as many as 1000 turtles may be caught annually by this fishery with an estimated mortality rate of 60%. Trammel nets were the main cause of marine turtle bycatch. Strandings coincided with setting of trammel nets that target siganids (Siganus luridus and Siganus rivulatus) and the majority of bycatch registered by fishers were caught in these gear types. We demonstrate a relatively simple approach to evaluating marine turtle bycatch, providing information that will allow local authorities and conservation groups to direct further research and possible mitigation measures.

The effect of thermal variance on the phenotype of marine turtle offspring.

Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.

Conflict between Dolphins and a Data-Scarce Fishery of the European Union

Fisheries depredation by marine mammals is an economic concern worldwide. We combined questionnaires, acoustic monitoring, and participatory experiments to investigate the occurrence of bottlenose dolphins in the fisheries of Northern Cyprus, and the extent of their conflict with set-nets, an economically important metier of Mediterranean fisheries. Dolphins were present in fishing grounds throughout the year and were detected at 28% of sets. Net damage was on average six times greater where dolphins were present, was correlated with dolphin presence, and the associated costs were considerable. An acoustic deterrent pinger was tested, but had no significant effect although more powerful pingers could have greater impact. However, our findings indicate that effective management of fish stocks is urgently required to address the overexploitation that is likely driving depredation behaviour in dolphins, that in turn leads to net damage and the associated costs to the fisheries.

The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus

We sampled 17 nesting sites for loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in Cyprus. Microplastics (<5 mm) were found at all locations and depths, with particularly high abundance in superficial sand. The top 2 cm of sand presented grand mean ± SD particle counts of 45,497 ± 11,456 particles m-3 (range 637-131,939 particles m-3). The most polluted beaches were among the worst thus far recorded, presenting levels approaching those previously recorded in Guangdong, South China. Microplastics decreased with increasing sand depth but were present down to turtle nest depths of 60 cm (mean 5,325 ± 3,663 particles m-3. Composition varied among beaches but hard fragments (46.5 ± 3.5%) and pre-production nurdles (47.8 ± 4.5%) comprised most categorised pieces. Particle drifter analysis hindcast for 365 days indicated that most plastic likely originated from the eastern Mediterranean basin. Worsening microplastic abundance could result in anthropogenically altered life history parameters such as hatching success and sex ratios in marine turtles.

Status and ecology of the Bonelli's Eagle, Aquila fasciatus, in the Pentadaktylos Mountain Range, Cyprus (Aves: Falconiformes)

The Bonellis Eagle is endangered in Europe, and the Cyprus population is estimated to be the 4th largest in Europe. During 2011 and 2012, ten active nests were confirmed in Pentadactylos Mountains with 8 additional sites meriting further investigation. Observations suggest a varied opportunistic diet largely based on Black Rat (Rattus rattus). Lowland wetland sites are confirmed as important foraging grounds. Bonellis Eagle is under a variety of anthropogenic threats in Pentadactylos Mountains most significantly hunting and poisoning, evidence for which are discussed.