Opportunistic visitors : long-term behavioural response of bull sharks to food provisioning in Fiji

Shark-based tourism that uses bait to reliably attract certain species to specific sites so that divers can view them is a growing industry globally, but remains a controversial issue. We evaluate multi-year (2004–2011) underwater visual (n = 48 individuals) and acoustic tracking data (n = 82 transmitters; array of up to 16 receivers) of bull sharks Carcharhinus leucas from a long-term shark feeding site at the Shark Reef Marine Reserve and reefs along the Beqa Channel on the southern coast of Viti Levu, Fiji. Individual C. leucas showed varying degrees of site fidelity. Determined from acoustic tagging, the majority of C. leucas had site fidelity indexes >0.5 for the marine reserve (including the feeding site) and neighbouring reefs. However, during the time of the day (09:00–12:00) when feeding takes place, sharks mainly had site fidelity indexes <0.5 for the feeding site, regardless of feeding or non-feeding days. Site fidelity indexes determined by direct diver observation of sharks at the feeding site were lower compared to such values determined by acoustic tagging. The overall pattern for C. leucas is that, if present in the area, they are attracted to the feeding site regardless of whether feeding or non-feeding days, but they remain for longer periods of time (consecutive hours) on feeding days. The overall diel patterns in movement are for C. leucas to use the area around the feeding site in the morning before spreading out over Shark Reef throughout the day and dispersing over the entire array at night. Both focal observation and acoustic monitoring show that C. leucas intermittently leave the area for a few consecutive days throughout the year, and for longer time periods (weeks to months) at the end of the calendar year before returning to the feeding site.

Pakistan's long-term stability remains concern to the US

The article discusses the implications of the Pakistani government's decision to begin talks with the Taliban.

Change in body mass associated with long-term fasting in a marine reptile : the case of green turtles (Chelonia mydas) at Ascension Island

Female green sea turtles (Chelonia mydas) nesting at Ascension Island (7°57'S, 14°22'W) in the middle of the Atlantic Ocean had a mean body mass (post oviposition) of 166.3 kg (range 107.5–243.5 kg, n = 119). Individuals lost mass slowly during the nesting season (mean mass loss 0.22 kg·d–1, n = 14 individuals weighed more than once). Gut-content analysis and behavioural observations indicated a lack of feeding. Females of equivalent-sized pinniped species that also do not feed while reproducing (nursing pups) on islands lose mass about 17 times faster. This comparatively low rate of mass loss by green turtles probably reflects their ectothermic nature and, consequently, their low metabolic rate. We estimate that a female turtle would lose only 19% of her body mass during the 143-day, 4400-km round trip from Brazil if she did not eat, laid 3 clutches of eggs, and lost 0.22 kg·d–.

Long-term satellite telemetry of the movements and habitat utilisation by green turtles in the Mediterranean

There is a relative paucity of data regarding the at-sea distribution and behaviour of marine turtles. This is especially true for the critically endangered green turtle Chelonia mydas population in the Mediterranean. Six adult female green turtles were equipped with satellite transmitters and tracked for periods of between 28 and 293 d following their final nesting of the season in northern Cyprus. Data elucidated hitherto unknown migratory pathways and highlighted the importance of North African coastal waters as feeding habitat for adults of this species. For three individuals, instruments transmitted detailed information on dive depth, dive duration and water temperature which afforded novel insights into behaviour during different stages of migration, feeding in the foraging grounds and most remarkably, during a period of midwinter diapause when water temperatures were generally below 25°C. Turtles showed fidelity to specific shallow inshore feeding areas and moved offshore to deeper wintering sites.

Long-term changes in abundance and distribution of microzooplankton in the NE Atlantic and North Sea

Long-term changes in mesozooplankton and phytoplankton populations have been well documented in the North Atlantic region, whereas data for microzooplankton are scarce. This neglected component of the plankton is a vital link in marine food-webs, grazing on smaller flagellates and cyanobacteria and in turn providing food for the larger mesozooplankton. We use the latest tintinnid (Ciliophora, Protista) data from the Continuous Plankton Recorder (CPR) survey in the NE Atlantic and North Sea to examine the phenology, distribution and abundance of this important group of ciliates. Presence/absence data came from 167 122 CPR samples collected between 1960 and 2009 and abundance data from 49 662 samples collected between 1996 and 2009. In the North Atlantic the genus Dictyocysta spp. dominated and Parafavella gigantea showed an increase in abundance around Iceland and Greenland. In the North Sea higher densities of Tintinnopsis spp., Favella serrata and Ptychocylis spp. were found. The presence of tintinnids in CPR samples collected in the North Atlantic has increased over the last 50 years and the seasonal window of high abundance has lengthened. Conversely in the North Sea there has been an overall reduction in abundance. We discuss possible drivers for these long-term changes and point the way forward to more holistic studies that examine how ecosystems, rather than just selected taxa, are responding to climate change.

Long-term thermal conditions on the nesting beaches of green turtles on Ascension Island

On 2 of the major nesting beaches used by green turtles Chelonia mydas on Ascension Island, we measured the sand temperature at nest depths throughout the year. For both beaches, the sand temperature was strongly correlated (r2 >= 0.94) with air temperature. We therefore used past records of air temperature to reconstruct sand temperatures on the different beaches throughout the nesting season between 1985 and 1998. This analysis showed that inter-annual differences in sand temperature were small and, while there were consistent thermal changes during the nesting season, over the 14 yr there was little overlap in the temperatures on the 2 beaches, with one being 2.6°C warmer, on average, than the other. This work suggests that inter-beach thermal variation is the major mechanism by which a range of incubation temperatures are realised on Ascension Island and hence is likely to facilitate the production of hatchlings of both sexes.

Long-term changes in the diel vertical migration behaviour of zooplankton

Samples historically collected and analysed by the Continuous Plankton Recorder survey were used to examine long-term (1958 to 1994) patterns in the normal diel vertical migration (NDVM) behaviour of 7 copepod taxa in the North Sea: Calanus finmarchicus C5-C6; Calanus spp. C1-C4; Centropages typicus; Centropages hamatus; Temora longicornis; Acartia clausii and Para-Pseudocalanus (this last group included all Paracalanus and Pseudocalanus species). The ratio of night:day abundance near the surface was used as a measure of the extent of NDVM. For all 7 taxa, the extent of NDVM between 1958 and 1994 co-varied with the abundance of herring Clupea harengus in the North Sea. Fisheries data show that during this period the herring stock was a good indicator of the overall abundance of planktivorous fish in the North Sea. These results suggest that changes in the abundance of planktivorous fish in the North Sea over recent decades have resulted in modifications in the NDVM behaviour of many zooplankton taxa.