Search

Olive ridleys (Lepidochelys olivacea) are the most numerous sea turtle species worldwide and also locally along the Pacific coast of Mexico. Published data on their distribution and nesting abundance along the coast of Nayarit and northern Jalisco, Mexico are, however, scarce. Here we describe the current extent of conservation activities and the history of efforts to protect sea turtles along this 394-km stretch of coastline. We found that 110 km (of the total of 394 km) are monitored by 18 sea turtle conservation programs, which in 2015 accounted for 43.2% of the total shoreline. Olive ridley sea turtle nesting was encountered on all monitored beaches. Our use of hatchery-protected nests as a measure of nesting levels is undoubtedly an underestimate of overall nesting in the region; however, it nevertheless provides a baseline of current nesting intensity in sites under conservation. Bahia de Banderas presented the highest nesting levels in the study area with 46.4% (3742 ± 904; mean ± SD) of t...

Temperature-dependent sex determination, or TSD, is a widespread phenomenon in reptiles. The shape of the relationship between constant incubation temperature and sex ratio defines the TSD pattern. The TSD pattern is considered a life-history parameter important for conservation because the wider the range of temperatures producing both sexes, the more resilient the species is to climate change impacts. We review the different published equations and methodologies that have been used to model TSD patterns. We describe a new flexible model that allows for an asymmetrical pattern around the pivotal temperature, which is the constant temperature producing both sexes in equal proportions. We show that Metropolis-Hastings with Markov chain produced by a Monte Carlo process has many advantages compared to maximum likelihood and is preferred. Finally, we apply the models to results from incubation experiments using eggs from the marine turtle Lepidochelys olivacea originating in Northeast Indian, East Pacific, and West Atlantic Regional Management Units (RMUs) and find large differences in pivotal temperatures but not in transitional ranges of temperatures.

In the eastern Pacific, peak olive ridley sea turtle (Lepidochelys olivacea) nesting occurs during the warmest months which coincide with the rainy season, yet as nesting takes place year-round, the small proportion of the nests laid during dry-low season are exposed to contrasting environmental conditions. Most of the studies on Pacific coast sea turtles have estimated sex ratios produced during the rainy-high season when the majority of conservation activities take place. Thus, dry-low season nests have on the whole been overlooked. Here we compared sex ratios and hatchling fitness for offspring produced during the dry and rainy seasons during 2015. We found that protected olive ridley clutches incubated during the dry-low season were exposed to lower temperatures, yielded higher hatchling success, produced 100% male offspring and larger, heavier hatchlings with better locomotor abilities. Our results highlight the critical value of monitoring and protecting sea turtle nests beyond the peak season (when nests can be protected more efficiently) to include low season nests, albeit at much lower densities, but which by yielding higher proportions of males and with greater locomotor capacities may be the key to population viability and adaptation to anthropogenic climate change.

Sea turtles and their nests face multiple threats on nesting beaches. Techniques have been developed to mitigate threats, these include relocating nests to fenced-off hatcheries or polystyrene boxes. The alteration of the nest’s natural environment may have direct effects on hatchling phenotype and locomotor performance. To test the effects of these two incubation conditions on proxies for hatchling fitness, we analysed locomotor performance (time to crawl 3 m and righting response) and phenotypic measures (weight and carapace length and width) of olive ridley sea turtle (Lepidochelys olivacea) hatchlings. We found that mean temperature was higher in hatcheries (30.5°C) than in polystyrene boxes (29.9°C) and that hatchlings incubated in polystyrene boxes had smaller straight carapace length (39.2 mm ± 2.0) and were significantly slower in crawl speed (CS) (0.0107 m s−1 ± 0.005) than those from hatcheries (SCL = 40.7 mm ± 1.3; CS = 0.018 m s−1 ± 0.005).

Marine turtle hatchling survival depends not only on suitable incubation temperatures allowing for viable embryo development but also adequate locomotor capacity to avoid predation while crawling from the beach to the sea and when swimming into the open ocean. To investigate the effects of temperature on swimming performance of olive ridley (Lepidochelys olivacea) hatchlings, we incubated eggs at different constant temperatures (24–34 °C) using a split-clutch approach. Swimming performance of hatchlings was tested and video-recorded for 24 h in static water under a day/night cycle (experiment 1) and for 30 min in continuously flowing water in the dark (experiment 2). Data from experiment 1 were evaluated visually to estimate the time of swimming activity. For experiment 2, we used software to calculate movement parameters from which hatchling performance was estimated. In both experiments, intermediate incubation temperatures (28–30 °C) were optimal not only for hatchling success and morphological dimensions but also for swimming performance, with 30 °C being the most favorable. Performance from hatchlings diminished with higher and lower temperatures, especially at the coldest range (26–27 °C). Phenotypic plasticity was observed from low and high incubation temperatures, with higher variation in performance among hatchlings from eggs incubated at 26–27 °C and 32–33 °C than for those incubated at 28–30 °C. Our results consistently showed that incubation temperature exerts the greatest influence on swimming performance and that maternal origin (clutch) has a significant effect on individual hatchling morphology. Given that the olive ridley year-round breeding leads to variable nest incubation temperatures in hot summers and cooler winter months, our results highlight the need for careful temperature management to produce hatchlings with optimal swimming capacities and, hence, highest survival probabilities.

Management of the critically endangered hawksbill turtle in the Wider Caribbean (WC) has been hampered by knowledge gaps regarding stock structure. We carried out a comprehensive stock structure re-assessment of 11 WC hawksbill rookeries using longer mtDNA sequences, larger sample sizes (N = 647), and additional rookeries compared to previous surveys. Additional variation detected by 740 bp sequences between populations allowed us to differentiate populations such as Barbados-Windward and Guadeloupe (F (st) = 0.683, P < 0.05) that appeared genetically indistinguishable based on shorter 380 bp sequences. POWSIM analysis showed that longer sequences improved power to detect population structure and that when N < 30, increasing the variation detected was as effective in increasing power as increasing sample size. Geographic patterns of genetic variation suggest a model of periodic long-distance colonization coupled with region-wide dispersal and subsequent secondary contact within the WC. Mismatch analysis results for individual clades suggest a general population expansion in the WC following a historic bottleneck about 100 000-300 000 years ago. We estimated an effective female population size (N (ef)) of 6000-9000 for the WC, similar to the current estimated numbers of breeding females, highlighting the importance of these regional rookeries to maintaining genetic diversity in hawksbills. Our results provide a basis for standardizing future work to 740 bp sequence reads and establish a more complete baseline for determining stock boundaries in this migratory marine species. Finally, our findings illustrate the value of maintaining an archive of specimens for re-analysis as new markers become available.

We investigated the dispersal, recruitment and migratory behaviour of the hawksbill sea turtle (Eretmochelys imbricata), among different life-history stages and demographic segments of the large hawksbill turtle aggregation at Mona Island, Puerto Rico. There were significant differences in both mitochondrial DNA (mtDNA) haplotype diversity and haplotype frequencies among the adult males, females and juveniles examined, but little evidence for temporal heterogeneity within these same groups sampled across years. Consistent with previous studies and the hypothesis of strong natal homing, there were striking mtDNA haplotype differences between nesting females on Mona Island and nesting females in other major Caribbean rookeries. Breeding males also showed strong, albeit weaker, genetic evidence of natal homing. Overall, Bayesian mixed-stock analysis suggests that Mona Island was the natal rookery for 79% (65-94%) of males in the aggregation. In contrast, the Mona Island rookery accounted for only a small subset of the new juvenile recruits to the foraging grounds or in the population of older juvenile hawksbills turtles on Mona. Instead, both new recruits and the older juvenile hawksbill turtles on Mona more likely recruited from other Caribbean rookeries, suggesting that a mechanism besides natal homing must be influencing recruitment to feeding habitats. The difference in the apparent degree of natal homing behaviour among the different life-history stages of hawksbill turtles at Mona Island underscores the complexity of the species' life-history dynamics and highlights the need for both local and regional conservation efforts.

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green ( Chelonia mydas ), loggerhead ( Caretta caretta ) and Kemp's ridley ( Lepidochelys kempii ) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico.

Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours -- the 'arribada' population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%- the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty-nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.

Resistance to different antibiotics was found in 26 of the 30 strains analyzed, more than 70% of the strains analyzed were resistant to carbenicillin and ampicillin and a significant correlation was found between the resistance to both antibiotics. Plasmids were found in 80% of the strains analyzed, and 11 different plasmid profiles were observed. The most common profile obtained had only a 21.2-kbp plasmid, a significant correlation was found between the presence of this plasmid and resistance to carbenicillin, although some exceptions could be detected. Plasmids were cured from a cephalothin resistant strain and reintroduced into the plasmid-free cell and into Escherichia coli DH5alpha, both strains gained resistance to this antibiotic.

Chromosome numbers in somatic (naupliar) and germinal (adult male) cells of bisexual Artemia populations from the Yucatan Peninsula, SE Mexico (Celestun, CEL; Chuburna, CHUB; Xtampu, XTAM; and Las Coloradas, COL), were compared to those from San Francisco Bay (SFB) and Great Salt Lake (GSL) individuals. Diploid and haploid counts permitted a double-check on results. SFB and GSL samples had low variability in number of chromosomes, with strong modal values of 2n=42 and n=21, typical for A. franciscana. Chromosome counts in the Yucatan brine shrimp samples indicated deviations from the normal 2n=42 karyotype (heteroploidy): COL had chromosome modes of 2n=42 and n=21; CEL of 2n=40 and n=20; CHUB had 2n=44 and n=22; XTAM 2n=48 and n=24. Chromocenter abundance (heterocromatic blocks of highly repetitive DNA) among populations indicated that the North American brine shrimp from SFB and GSL had a mean of 15.9 and 15.1 chromocenters, respectively. From the Yucatan brine shrimp, COL had a variable number of chromocenters, ranging from 5 to 15 with a mean value of 9.9. The other three Artemia populations had much fewer chromocenters (CEL 1–3, XTAM 1–8, and CHUB 1–4). Heteromorphic sex chromosomes were apparent in some Yucatan karyotypes preparations. The haplotype condition in the Yucatan Artemia populations, though similar to that found in some Italian A. salina populations, is reported for the first time in New World Artemia. This cytological characteristic of the Yucatan Artemia, in conjunction with their morphological and allozyme differentiation, could provide new insight for the role of chromosome rearrangements in the evolutionary process of Artemia in the New World.

Two groups of nauplii from the brine shrimp ( Artemia franciscana ) were enriched with different bacteria, and the dynamics of bacterial uptake by the nauplii were observed. This study showed that the efficiency of Artemia nauplii in bioencapsulating bacteria strongly depends on the type of bacteria used, time of exposure, and status (live or dead) of the bacteria.

A new system named AquaPlak® designed for evaluating heterotrophic bacteria and those belonging to the genus Vibrio was compared to the standard method of total viable count by spread plating. Water samples from a shrimp farm were evaluated by the two procedures over a 3-month period. The spread plating technique gave significantly higher viable counts for both Vibrio and heterotrophic bacteria than the AquaPlak® system.

The Kemp's ridley sea turtle (Lepidochelys kempi) is restricted to the warm temperate zone of the North Atlantic Ocean, whereas the olive ridley turtle (L. olivacea) is globally distributed in warm-temperate and tropical seas, including nesting colonies in the North Atlantic that nearly overlap the range of L. kempi. To explain this lopsided distribution, Pritchard (1969) proposed a scenario in which an ancestral taxon was divided into Atlantic and Pacific forms (L. kempi and L. olivacea, respectively) by the Central American land bridge. According to this model, the olive ridley subsequently occupied the Pacific and Indian Oceans and recently colonized the Atlantic Ocean via southern Africa. To assess this biogeographic model, a 470 bp sequence of the mtDNA control region was compared among 89 ridley turtles, including the sole L. kempi nesting population and 7 nesting locations across the range of L. olivacea. These data confirm a fundamental partition between L. olivacea and L. kempi (p=0.052-0.069), shallow separations within L. olivacea (p=0.002-0.031), and strong geographic partitioning of mtDNA lineages. The most divergent L. olivacea haplotype is observed in the Indo-West Pacific region, as are the central haplotypes in a parsimony network, implicating this region as the source of the most recent radiation of olive ridley lineages. The most common olive ridley haplotype in Atlantic samples is distinguished from an Indo-West Pacific haplotype by a single nucleotide substitution, and East Pacific samples are distingushed from the same haplotype by two nucleotide substitutions. These shallow separations are consistent with the recent invasion of the Atlantic postulated by Pritchard (1969), and indicate that the East Pacific nesting colonies were also recently colonized from the Indo-West Pacific region. Molecular clock estimates place these invasions within the last 300,000 years.

The nesting colony of green sea turtles (Chelonia mydas) at Guanahacabibes Peninsula Biosphere Reserve and National Park is one of the largest in the Cuban archipelago; however, little information about its nesting ecology is available. Temporal and spatial variation in nesting and reproductive success as well as morphometric characteristics of gravid females were used to ecologically characterize this colony. Nine beaches of the Southernmost coast of Guanahacabibes Peninsula were monitored for 14 years (1998-2012) to determine green turtle nesting activity, from May to September (peak nesting season in this area). Beach dimensions were measured to determine nest density using the length and the area. Afterward the beaches were divided in two categories, index and secondary. Females were measured and tagged to compare new tagged females (823) with returning tagged females (140). Remigration interval was also determined. Temporal variation was identified as the annual number of nesting emergences and oviposits per female, with apparent peaks in reproductive activity on a biennial cycle in the first six years followed by periods of annual increase in nest number (2003-2008) and periods of decreasing number of nests (2010-2012). We also found intra-seasonal variation with the highest nest- ing activity in July, particularly in the second half of the month. The peak emergence time was 22:00-02:00hr. In terms of spatial variation, smaller beaches had the highest nest density and nesting was more frequent 6-9m from the high tide line, where hatchling production was maximized although hatchling success was high on average, above 80%. Morphometric analysis of females was made and newly tagged turtles were smaller on average than remigrants. Our results are only a first attempt at characterizing Guanahacabibes' populations but have great value for establishing conservation priorities within the context of national management plans, and for efficient monitoring and protection of nesting beaches.Rev. Biol. Trop. 61 (4): 1935-1945. Epub 2013 December 01.

Laboratory cultures of Artemia franciscana grown under batch regimes at constant temperatures (28 °C) and salinity (35 g 1-1), three initial food concentrations (0.1, 0.4 and 1 M cells ml-1), various daily food rations (0.1-9 M Dunaliella tertiolecta cells Artemia -1), and different population densities (1–16 ind ml-1) were used to develop a model of population growth. Growth rates and gross growth efficiencies (K 1) were largely independent of population densities and initial food concentrations but determined by age and daily amount of food ingested. While maximum growth rates were found with the highest rations, K 1 max peaked at rations of 0.5 million cells d-1 and decreased at feeding levels above this. A contour plot showing the trend relating K 1to Artemia size and ingestion rate in combination and was used to model growth in analogous controlled feeding conditions. Computer simulations using this model paralleled published results of final 15-day average individual sizes of Artemia. Optimal results for near constant food utilization are predicted for high initial population densities (100 Artemia nauplii ml-1) and daily culls of enough animals to equilibrate food demand with food availability. This strategy could permit a range of Artemia sizes harvested, maximize final individual sizes and retain high total yields (> 1.2 kg dry wt 1-1). Effects of different culture strategies are discussed.

A new character for the distinction of subgenera in postlarval shrimp of the genus Penaeus from the Gulf of California (Mexico) is described. The four main shrimp species, Penaeus stylirostris, P. vannamei, P. californiensis, and P. brevirostris, present clear differences in the internal/external length ratio of the two first segments of the antennular flagella. Penaeus stylirostrisand P. vannamei, both belonging to the subgenus Litopenaeus, have low ratio values, e.g., mean values ranging from 0.4-1.0, whereas P. californiensis and P. brevirostris of the subgenus Farfantepenaeus have high ratio values, e.g., mean values ranging from 1.1-3.1. When total ranges are considered, overlapping occurs in only one of the four categories in which the postlarvae were grouped according to the number of dorsal teeth of the rostrum. Even in this case, the subgeneric distinction is possible by comparing the level of the distal margin of the second segment of the internal antennular flagellum in relation to that of the first segment of the external antennular flagellum. Differences are more pronounced within each of the categories. An identification method to the specific level is given after the subgeneric discrimination. The greatest advantage of this character over the use of chromatophore distribution patterns is the feasability of identifying postlarvae of Penaeus after prolonged storage periods.

1. 1. Mitochondrial malic enzyme (ME M ) in the Atlantic salmon, Salmo salar L., is encoded by two loci, whose products are distinguishable by electrophoresis and combine as tetramers. 2. 2. One of the ME M loci is polymorphic in an Irish population, with two alleles segregating at frequencies of 0.45 and 0.55. 3. 3. The supernatant form of the enzyme, which migrates anodally to the mitochondrial form, is encoded by one or possibly two invariant loci.