Satellite tracking of migrating loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) displaced in the open sea

Loggerhead turtles (Caretta caretta) are known to migrate towards fixed, individually-specific residential feeding grounds. To study their spatial behaviour and their navigational ability, five loggerheads nesting in South Africa were captured when about to start their postnesting migration and tracked by satellite after having been displaced from their usual migratory route. The first turtle, released south of Madagascar about 1,148 km from the capture site, moved west up to mainland Africa and then reached her feeding grounds by following the coast. A second turtle, released farther away (2,140 km) close to La Réunion Island, stopped for some time on the Madagascar east coast, then turned southwards to round the island and regain the African mainland in the northwest, without however allowing us to establish the location of her residential grounds. Three other turtles were released off the Tanzanian coast, 2,193 km north of their nesting area, at the northern edge of the distribution of the feeding grounds along the African coast. All of them headed north, and one turtle found her residential grounds located north of the release site. The other two females started long-distance oceanic wanderings in which they crossed nearly the entire Indian Ocean, apparently being transported by the sea currents of the region. We conclude that adult loggerhead turtles are apparently unable to compensate for the displacement and can return to a pelagic life style characteristic of juvenile turtles. These findings suggest that South African loggerheads rely on simple orientation mechanisms, such as the use of the coastline, as a guide, and compass orientation, possibly integrated by spatiotemporal programmes and/or acquired maps of familiar sites.Communicated by R. Cattaneo-Vietti, Genova     

Different growth rates between loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) of Mediterranean and Atlantic origin in the Mediterranean Sea

We estimated for the first time the growth rates of loggerhead sea turtles of Mediterranean and of Atlantic origin found in the Mediterranean Sea, combining both skeletochronological and genetic analyses. Our growth models suggested that the growth rate of loggerhead sea turtles of Mediterranean origin was faster than that of their conspecifics with an Atlantic origin exploiting the feeding grounds in the Mediterranean Sea. The age at maturity for Mediterranean origin loggerhead sea turtles, estimated using our best fitting model, was 24 years, which suggests that loggerhead sea turtles nesting in the Mediterranean are not only smaller than those nesting in the western North Atlantic but also younger.     

Seasonal distribution patterns of juvenile loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) following capture from a shipping channel in the Northwest Atlantic Ocean

Thirty-four juvenile loggerhead sea turtles captured by trawling from the Charleston, South Carolina (USA), shipping channel (32°42′N; −79°47′W) between May 2004 and August 2007 were tagged with satellite transmitters to assess the extent to which they remained near the capture location given their collection along a seasonal migratory corridor. Seventy-five percent of juveniles were classified as seasonal residents. Migrants predominantly swam north in the spring and nomads wandered south in the summer, but predictive indicators for non-resident status were not identified. All but one juvenile generally remained south of 34°N, within 40 km of shore, and in waters <30 m deep throughout the year. Nine of 14 loggerhead sea turtles monitored during the winter remained exclusively over the continental shelf, three briefly occurred in oceanic habitats, and two foraged extensively in oceanic habitats. Residents distributed >15 km from shore between spring and autumn were three times as likely to occur in oceanic habitats in winter. Modest seasonal movements contrasted with adults tagged at similar latitudes and with juveniles tagged further north and suggest distinct foraging groups within a regional foraging ground.     

Patterns in the emergence of green (<Emphasis Type="Italic">Chelonia mydas</Emphasis>) and loggerhead (<Emphasis Type="Italic">Caretta caretta</Emphasis>) turtle hatchlings from their nests

The emergence patterns of both green (Chelonia mydas) and loggerhead (Caretta caretta) turtle hatchlings were observed in great detail over three seasons at Alagadi beach, northern Cyprus. In total, 38 green turtle and 50 loggerhead turtle nests were monitored, accounting for the emergence of 2,807 and 2,259 hatchlings, respectively. We quantified these emergences into 397 green turtle and 302 loggerhead turtle emergence groups. Overall, 85.0% of green turtle and 79.5% of loggerhead turtle groups emerged at night; these accounted for 85.5 and 90.8% of hatchlings, respectively. The remaining emergences were dispersed throughout the day for green turtle nests but confined to the morning in loggerhead turtle nests. Hatchling emergence from individual nests occurred over periods of between 1 and 7 nights, with most hatchlings typically emerging on the first night. Group sizes of green turtles emerging during the day were significantly smaller than those emerging at night. Hatchlings of both species that emerged from nests during the day had longer emergence durations than those that emerged from nests at night only.Communicated by R.J. Thompson, St. Johns     

Habitat use by loggerhead sea turtles <Emphasis Type="Italic">Caretta caretta</Emphasis> off the coast of eastern Spain results in a high vulnerability to neritic fishing gear

Previous studies of loggerhead sea turtles have concluded that drifting longlines were the main threat for immature specimens in the western Mediterranean, because immature loggerhead sea turtles mainly inhabit oceanic waters. However, recent aerial surveys have revealed large numbers of immature loggerhead sea turtles over the continental shelf of eastern mainland Spain, where turtles are exposed to neritic fishing gears but not to drifting longlines. We satellite-tracked seven loggerhead sea turtles (minimum straight carapace length (SCLmin) range: 36.5–55.0 cm) to assess whether the turtles in this region are vagrants from the adjoining oceanic regions or whether these loggerheads mostly inhabit the continental shelf. Satellite-tracking revealed that six of the tagged turtles avoided the oceanic realm and made extended use of the continental shelf, whereas only one individual could be considered a true vagrant as it avoided the continental shelf and primarily used the oceanic habitat. These results are in sharp contrast with those previously reported for immature loggerhead sea turtles of similar size from the south-western Mediterranean and fit well a relaxed ontogenic model that was recently proposed for loggerhead sea turtles in the central Mediterranean. Furthermore, these results demonstrate the vulnerability of loggerhead sea turtles of eastern mainland Spain to neritic fishing gears, as three of the seven turtles died and one was bycaught incidentally while being tracked over the continental shelf.     

A model of area fidelity,nomadism, and distribution patterns of loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) in the Mediterranean Sea

Sea turtle tagging carried out in Italy in the period 1981–2006 resulted in 125 re-encounters of loggerhead turtles (Caretta caretta) after a mean of 2.5 years, from different marine areas in the Mediterranean. At first finding, turtles ranged 25–83 cm of curved carapace length. Data were analyzed according to size, area, habitat type, season, in order to provide indication of movement patterns. When integrated with other information, results indicate that: (1) a part of turtles in the oceanic stage show a nomad behavior with movements among different oceanic areas; (2) another part show fidelity to an oceanic area; (3) turtles in the neritic stage show fidelity to neritic areas, and once settled to one area, change to other neritic areas is unlikely; (4) nomad oceanic turtles are significantly larger than sedentary ones, and also larger than turtles found in neritic areas; it is hypothesized that these could be Atlantic turtles that eventually leave the Mediterranean; (5) ecological transition from oceanic to neritic habitats occurs at a wide range of sizes, and some turtles may have a very brief oceanic stage; (6) turtles in the oceanic stage are more likely to recruit to neritic areas close to their oceanic areas than to distant ones; (7) part of turtles from some Mediterranean nesting beaches might frequent a relatively limited area range, including both oceanic and neritic areas; (8) in most of the Mediterranean, latitudinal seasonal migrations are unlikely. A general model of movement patterns of loggerhead turtles in the Mediterranean is proposed.     

Distributional patterns of adult male loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) in the vicinity of Cape Canaveral,Florida, USA during and after a major annual breeding aggregation

Satellite transmitters were attached to 25 reproductively active and four inactive adult male loggerhead sea turtles (86.6–107.0 cm SCLmin) captured from the Port Canaveral, FL, USA shipping channel to assess horizontal and vertical distributions. During the breeding period, male loggerheads aggregated (44% of 755 turtle days) in a 117.6 km² core area that encompassed the shipping channel. Median dive duration during the breeding period was 27 min (IQR = 15–42 min) and males spent 4% (IQR = 3–5%) of the time at the surface, with significantly shorter dives associated with reproductively active males. Migrant and resident males dispersed concurrently, with residents shifting > 30 km east across the continental shelf over a more protracted departure schedule than migrants. Dive duration and time spent at the surface increased through the fall. Cluster analysis revealed the strongest association for dive duration with sea state during and after the breeding period, with significantly longer dives during more turbulent conditions. In contrast, univariate associations with surface interval duration were not elucidated.     

Loggerhead turtle (<Emphasis Type="Italic">Caretta caretta</Emphasis>) matrilines in the Mediterranean: further evidence of genetic diversity and connectivity

We re-sequenced 815 bp of the mtDNA of loggerhead turtles from a population nesting in Calabria (southern Italy), which was found recently. Non-invasive sampling was applied and information on deposition date and place was used to avoid possible resampling of nesting females. Among 38 nests laid by independent females, we found the common haplotype CC-A2.1 (57.9%) and two other haplotypes which have never been described in Mediterranean nesting grounds, CC-A20.1 (36.8%) and CC-A31.1 (5.3%). Calabria harbors the highest intra-population diversity among 11 Mediterranean nesting populations. Our findings narrow the gap between haplotypes recorded in feeding grounds and those found in nesting grounds. Analyses of population structure show a strong maternal isolation, with Calabria and east Turkey displaying far more diversity than expected considering their census size. These observations suggest that recurrent female founder effects from sources yet to be identified in the Atlantic or in the Mediterranean may have shaped the pattern of mtDNA diversity in this latter basin. Our results provide evidence that the Ionian Calabrian sites should be protected because of the high diversity found there. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The relationship between loggerhead turtle (<Emphasis Type="Italic">Caretta caretta</Emphasis>) movement patterns and Mediterranean currents

Previous studies have shown that loggerhead sea turtles (Caretta caretta), monitored by satellite telemetry, complete long-distance migration between the western and eastern Mediterranean basins following a seasonal pattern. This study investigated if these migration routes may be influenced by surface currents by superimposing the tracks of three loggerhead turtles (curved carapace length >55 cm), migrating from the western to the eastern Mediterranean basin, on Lagrangian data of current developed into pseudo-eulerian speed fields. The average travel speed of the turtles was 1.6 km h⁻¹ and did not depend on the current speed or direction. We observed a connection between surface currents and the turtles’ migration routes, although not a conclusive one. These observations show that neritic stage loggerhead turtles conduct migration in two distinct alternate phases: the first characterized by high and constant speed of travel both when swimming with or against currents and the second typified by low travel speeds and a good concurrence between the trailed routes and the course of the currents. These two phases corresponded to two types of movements, one where the turtle migrates actively to reach a specific destination (either neritic foraging, wintering or nesting ground) and the other, where the turtle drifts with the mesoscale current and forages pelagically. It seemed thus, that the influence of currents on a turtle’s movements depends on the turtle’s momentary behaviour and location of residence.     

Tracking hawksbill sea turtles (<Emphasis Type="Italic">Eretmochelys imbricata</Emphasis>) during inter-nesting intervals around Barbados

Hawksbill sea turtles (Eretmochelys imbricata) nesting in Barbados (Needham’s Point, 13° 04′ 41.33′′ N, 59° 36′ 32.69′′W) were outfitted with GPS dataloggers over three breeding seasons (2008–2010) to track movement during inter-nesting intervals. Most females established spatially restricted resident areas up current and within 7 km of the nesting beach where they spent the majority of the inter-nesting interval. Females nesting earlier in the season settled on shallower sites. Only experienced remigrant turtles occupied the most distant resident areas. Females tracked for multiple inter-nesting intervals exhibited site fidelity, but the area contracted and the activity of females decreased with each successive interval. Hawksbills may trade off site characteristics with distance from the nesting beach and reduce activity over the course of the breeding season to optimise energy reserves during inter-nesting intervals.     

Auditory defence in the peacock butterfly (<Emphasis Type="Italic">Inachis io</Emphasis>) against mice (<Emphasis Type="Italic">Apodemus flavicollis</Emphasis> and <Emphasis Type="Italic">A. sylvaticus</Emphasis>)

Morphological and behavioural traits can serve as anti-predator defence either by reducing detection or recognition risks, or by thwarting initiated attacks. The latter defence is secondary and often involves a ‘startle display’ comprising a sudden release of signals targeting more than one sensory modality. A suggested candidate for employing a multimodal defence is the peacock butterfly, Inachis io, which, by wing-flicking suddenly, produces sonic and ultrasonic sounds and displays four large eyespots when attacked. The eyespots make small birds retreat, but whether the sounds produced thwart predator attacks is largely unknown. Peacocks hibernate as adults in dark wintering sites and employ their secondary defence upon encounter with small rodent predators during this period. In this study, we staged predator–prey encounters in complete darkness in the laboratory between wild mice, Apodemus flavicollis and Apodemus sylvaticus, and peacocks which had their sound production intact or disabled. Results show that mice were more likely to flee from sound-producing butterflies than from butterflies which had their sound production disabled. Our study presents experimental evidence that the peacock butterfly truly employs a multimodal defence with different traits targeting different predator groups; the eyespots target birds and the sound production targets small rodent predators.     

Emergence pattern of loggerhead turtle (<Emphasis Type="Italic">Caretta caretta</Emphasis>) hatchlings from Kyparissia Bay,Greece

The present study describes the emergence pattern of loggerhead sea turtle hatchlings (Caretta caretta) from a nesting beach in Kyparissia Bay (Greece). We try to establish the role played by hatchling biometry, nest relocation and distance from nest to the sea on this emergence pattern. We surveyed a total of 32 nests, and found long emergence periods (mean = 6.7 nights). The majority of emergences occurred at night, mainly between 0030 and 0100 hours, and in small groups. Most of the hatchlings emerged from the nests the first night. We found no clear trend when we studied the effect of hatchling biometry between successive emergence days. We also found that relocation of the nests did not significantly affect the emergence pattern. However, we noted that in the relocated nests, hatchlings emerged in smaller groups. Emergence periods were inversely related to distance from the sea. In short, factors such as climate conditions, relocation and nest distance to the sea appear to have some effect on the emergence pattern. Therefore, they should be taken into account in both biological studies and management plans for sea turtle nesting beaches. Our results suggest leaving an extended period between the first emergence of hatchlings and the excavation of nests by researchers in future studies in the area.     

Histological investigation of the reproductive cycles of the limpets <Emphasis Type="Italic">Patella </Emphasis><Emphasis Type="Italic">vulgata</Emphasis> and <Emphasis Type="Italic">Patella ulyssiponensis</Emphasis>

This study devised a staging system for, and monitored, the gonad development of the limpet species Patella vulgata and Patella ulyssiponensis on the South West coast of Ireland using histological techniques. Maturation began in the males of both species in January and in the females it began in March. There was no statistical difference in gonad development between sexes and between species. Spawning in the male P. vulgata occurred from September to December 2003 and in September and October 2004. In female P. vulgata spawning occurred from October to December 2003, no spawning of females was observed in 2004. In male P. ulyssiponensis spawning occurred in November and December 2003 and from September 2004 to December 2004. Spawning was observed from November 2003 to January 2004 and in September 2004 in female P. ulyssiponensis. Sex ratios also varied between the species and between months sampled. Nevertheless more males were observed in both species.     

Movements and site fidelity of grass shrimp (<Emphasis Type="Italic">Palaemonetes pugio</Emphasis> and <Emphasis Type="Italic">P. vulgaris</Emphasis>) in salt marsh intertidal creeks

Grass shrimp are abundant residents of shallow-water habitats in US Atlantic and Gulf coast estuaries. Mark-recapture events determined the extent and direction of their movements in meso-tidal salt marsh creeks at North Inlet, South Carolina. Microwire-tagged Palaemonetes vulgaris demonstrated high fidelity for a dock in a subtidal channel. In the 48 days following release, 11 % of the 422 tagged shrimp were recaptured and 99 % of all recaptures were made there an average of 14 days post-release. Palaemonetes pugio, which favored the use of shallow intertidal areas, exhibited moderate fidelity for pools within creek beds with 53 % of the recaptured shrimp collected at the release site. Higher fidelity was observed for confluences of intertidal creeks and the subtidal channels. Of the 5565 shrimp released with coded microwire tags, 7.5 % were recaptured and 98 % of those recaptures were at release sites up to 53 days later. During another event, P. pugio released 235 m from their origin demonstrated relatively low fidelity for the new site and a lack of homing behavior. Of the 544 tagged shrimp, 3 % were recaptured; only 40 % of those recaptured were from the release site. Site fidelity is a mechanism by which previously discovered large and consistent differences in grass shrimp use of neighboring intertidal creek basins can be sustained over weeks, seasons, and years. Spatial variations and the tendency of these keystone organisms to resist relocation by tidal currents and occupy certain areas for extended periods should be considered in decisions about proposed alterations to creeks and shorelines.     

Genetic analysis of tuna populations,<Emphasis Type="Italic"> Thunnus thynnus thynnus</Emphasis> and<Emphasis Type="Italic"> T</Emphasis>.<Emphasis Type="Italic"> alalunga</Emphasis>

The genetic population structures of Atlantic northern bluefin tuna ( Thunnus thynnus thynnus) and albacore ( T. alalunga) were examined using allozyme analysis. A total of 822 Atlantic northern bluefin tuna from 18 different samples (16 Mediterranean, 1 East Atlantic, 1 West Atlantic) and 188 albacore from 5 samples (4 Mediterranean, 1 East Atlantic) were surveyed for genetic variation in 37 loci. Polymorphism and heterozygosity reveal a moderate level of genetic variability, with only two highly polymorphic loci in both Atlantic northern bluefin tuna ( FH* and SOD- 1*) and albacore ( GPI- 3* and XDH*). The level of population differentiation found for Atlantic northern bluefin tuna and albacore fits the pattern that has generally been observed in tunas, with genetic differences on a broad rather than a more local scale. For Atlantic northern bluefin tuna, no spatial or temporal genetic heterogeneity was observed within the Mediterranean Sea or between the East Atlantic and Mediterranean, indicating the existence of a single genetic grouping on the eastern side of the Atlantic Ocean. Very limited genetic differentiation was found between West Atlantic and East Atlantic/Mediterranean northern bluefin tuna, mainly due to an inversion of SOD- 1* allele frequencies. Regarding albacore, no genetic heterogeneity was observed within the Mediterranean Sea or between Mediterranean and Azores samples, suggesting the existence of a single gene pool in this area.     

Comparative life-history study on sympatric hyperiid amphipods (<Emphasis Type="Italic">Themisto pacifica</Emphasis> and <Emphasis Type="Italic">T</Emphasis>. <Emphasis Type="Italic">japonica</Emphasis>) in the Oyashio region,western North Pacific

Life-history features of the sympatric amphipods Themisto pacifica and T. japonica in the western North Pacific were analyzed based on seasonal field samples collected from July 1996 through July 1998, and data from laboratory rearing experiments. T. pacfica occurred throughout the year, with populations peaking from spring to summer. In contrast, T. japonica were rare from autumn to early winter, but became abundant in late winter to spring. Mature T. pacifica females and juveniles occurred together throughout the year, indicating year-round reproduction. Mature T. japonica females were observed only in spring, and juveniles occurred irregularly in small numbers, suggesting limited, early-spring reproduction in this study area. Size composition analysis of T. pacifica identified a total of eight cohorts over the 2 years of the study. Due to the smaller sample size and rarity of mature females (>9.6 mm) and males (>7.1 mm), cohort analyses of T. japonica were not comparable. Laboratory rearing of specimens at 2°C, 5°C, 8°C and 12°C revealed that a linear equation best expressed body length growth by T. pacifica, while a logistic equation best expressed body length growth by T. japoncia. Combining these laboratory-derived growth patterns with maturity sizes of wild specimens, the minimum and maximum generation times of females at a temperature range of 2–12°C were computed as 32 days (12°C) and 224 days (2°C), respectively, for T. pacifica, and 66 days (12°C) and 358 days (2°C), respectively, for T. japonica. The numbers of eggs or juveniles in females marsupia increased with female body length and ranged from 23 to 64 for T. pacifica and from 152 to 601 for T. japonica. Taking into account the number of mature female instars, lifetime fecundities were estimated as 342 eggs for T. pacifica and 1195 eggs for T. japonica. Possible mechanisms for the coexistence of these two amphipods in the Oyashio region are also discussed.Communicated by O. Kinne, Oldendorf/Luhe     

Migratory and reproductive movements of male leatherback turtles (<Emphasis Type="Italic">Dermochelys coriacea</Emphasis>)

The biology of the endangered leatherback turtle (Dermochelys coriacea) at sea is poorly understood. As research has been almost exclusively limited to studies of nesting females, the movements of male turtles and the timing and location of mating activity have remained unknown. We report on the first deployments of satellite tags on male leatherbacks. Male migration to and residency in waters adjacent low-latitude nesting beaches in the western Atlantic suggest that this is where mating occurs, and return migration to these areas reveals male fidelity for breeding sites. Rate of travel decreased markedly after arriving in coastal breeding areas, where males remained for up to 96 days before assuming northward migrations. The initiation of these northward migrations coincided with peak nesting activity in adjacent nesting colonies. Data from satellite-linked time-depth recorders attached to two males revealed diel dive patterns in breeding areas and marked differences in diving behaviour between migratory and breeding periods in one turtle. When male turtles were in waters adjacent nesting colonies, their movements differed from those reported for nesting females, with females ranging farther from shore. Our results suggest that male leatherbacks may be vulnerable to entanglement in coastal fishing gear in waters adjacent nesting beaches.Communicated by R.J. Thompson, St. Johns     

Heart rate reflects osmostic stress levels in two introduced colonial ascidians <Emphasis Type="Italic">Botryllus schlosseri</Emphasis> and <Emphasis Type="Italic">Botrylloides</Emphasis><Emphasis Type="Italic">violaceus</Emphasis>

The influence of abiotic factors on the establishment and success of invasive species is often difficult to determine for most marine ecosystems. However, examining this relationship is critical for predicting the spread of invasive species and predicting which habitats will be most vulnerable to invasion. Here we examine the mortality and physiological sensitivity to salinity of adult colonies of the colonial ascidians Botryllus schlosseri and Botrylloides violaceus. Adult colonies of each species were exposed to abrupt changes in salinity (5, 10, 15, 20, 25, 30 psu) in the laboratory. Salinity ranges used in the laboratory corresponded with those of the field distributions of B. violaceus and B. schlosseri in the Great Bay Estuary, NH. Heart rate was used as a proxy for health to assess the condition of individual colonies. Heart rates were monitored daily for approximately 2 weeks. Results revealed that both species experienced 100% mortality after 1 day at 5 psu and that their heart rates declined with decreasing salinity. Heart rates of B. schlosseri remained consistent between 15 and 30 psu and slowed at 10 psu. Heart rates of B. violaceus remained constant between 20 and 30 psu, but slowed at 15 psu. These laboratory results corresponded to the distribution of these species in estuaries, indicating salinity is a key factor in the distribution and dominance of B. schlosseri and B. violaceus among coastal and estuarine sites. Furthermore, physiological differences to salinity were found between colonies of B. schlosseri in the Venetian Lagoon and colonies in Portsmouth Harbor, suggesting adaptation to environmental variables.     

Predation on egg capsules of <Emphasis Type="Italic">Zidona</Emphasis><Emphasis Type="Italic">dufresnei</Emphasis> (Volutidae): ecological implications

Among the diverse patterns of energy allocation to the offspring of gastropods, the presence of egg capsules to protect embryos is common. Females of the edible snail Zidona dufresnei attach egg capsules to hard substrates in shallow Argentine Patagonian waters (40°45′S, 64°56′W) during spring-summer. Embryonic development takes about 30 days at 22°C. In this study, three likely capsule predator species and the marks left by each on egg capsule walls were identified in laboratory experiments in February 2010. Abundances of predators and egg capsules with evidence of predation were assessed in the field in the summers of 2010 and 2011. Under laboratory conditions (N = 10 replicates per treatment and control), the predation rate by the chiton Chaetopleura isabellei was the highest (up to 90%), followed by the gastropod Tegula patagonica and the crab Neohelice granulata (~20% each). Nearly 60% of 41 capsules found in the field showed signs of predation. According to the marks identified in the laboratory, C. isabellei was responsible for 79% of this predation, and T. patagonica for the rest. Predation appears to be important during the encapsulated early life and could be an agent for selecting for resistant capsule walls and a relatively shorter development time.