scholarly journals The acoustic identification and enumeration of scyphozoan jellyfish, prey for leatherback sea turtles (Dermochelys coriacea), off central California

2010 ◽  
Vol 67 (8) ◽  
pp. 1739-1748 ◽  
Author(s):  
Tanya R. Graham ◽  
James T. Harvey ◽  
Scott R. Benson ◽  
Josiah S. Renfree ◽  
David A. Demer
Keyword(s):  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Target Strength ◽  
Diameter Distribution ◽  
Bell Diameter ◽  
Leatherback Turtles ◽  
Central California ◽  
Leatherback Sea Turtles ◽  
Acoustic Identification ◽  
Scyphozoan Jellyfish

Abstract Graham, T. R., Harvey, J. T., Benson, S. R., Renfree, J. S., and Demer, D. A. 2010. The acoustic identification and enumeration of scyphozoan jellyfish, prey for leatherback sea turtles (Dermochelys coriacea), off central California. – ICES Journal of Marine Science, 67: 1739–1748. Acoustic-sampling techniques were developed to estimate the abundance and distribution of scyphozoan jellyfish, prey for leatherback turtles foraging off central California. Acoustic data were analysed from regions where jellyfish were present or absent from corresponding net tows. Empirical data on bell-diameter distribution (mean 26.2 cm; s.d. 10.6) were used to estimate target strength (TS; dB re 1 m2) at 18, 38, 70, 120, and 200 kHz using a distorted-wave Born approximation scattering model. TS measurements of in situ animals at 38 and 200 kHz averaged −63.9 and −70.5 dB, compared with the model estimates of −54.9 and −64.0 dB, respectively. The model estimates of TS at 18, 70, and 120 kHz were −53.9, −59.9, and −61.8 dB, respectively. Using these TS estimates, an algorithm was developed to extract jellyfish echoes from total acoustic backscatter. Echo-integration methods applied to regions where net catches contained jellyfish resulted in an estimate of mean numerical abundance of 3217 jellyfish (s.d. 2276) with a mean density of 251 522 jellyfish nautical mile−2 (s.d. 57 504) and a mean concentration of 0.003 jellyfish m−3 (s.d. 0.002). The novel methods developed will help characterize prey resources for leatherback turtles off central California.

scholarly journals The Effects of Nest Location and Beach Environment on Hatching Success for Leatherback (Dermochelys Coriacea) and Green (Chelonia Mydas) Sea Turtles on Bioko Island, Equatorial Guinea

2021 ◽  
Author(s):  
Callie A. Veelenturf ◽  
Elizabeth M. Sinclair ◽  
Peter Leopold ◽  
Frank V. Paladino ◽  
Shaya Honarvar
Keyword(s):  
Green Turtle ◽  
Hatching Success ◽  
Sea Turtles ◽  
Chelonia Mydas ◽  
Dermochelys Coriacea ◽  
Equatorial Guinea ◽  
Leatherback Turtles ◽  
Nest Location ◽  
Bioko Island ◽  
Elevation Range

Abstract Hatching success in sea turtles is hindered by a variety of biotic and abiotic factors. This study of the nesting ecology of leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles, investigated how several environmental factors and beach characteristics on Bioko Island, Equatorial Guinea influence sea turtle reproductive success. Average clutch hatching success was 40.4% for green turtles and 41.73% for leatherback turtles. For leatherback turtles, clutch elevation relative to the high tide line (HTL) was found to be the most influential factor in determining hatching success, highlighting the sensitivity of this species to sea level rise (SLR). Multiple linear regression analysis demonstrated that nest distance to vegetation and sand conductivity also played significant roles in leatherback clutch hatching success. For leatherback clutches, 33% percent of experimental nests were affected by inundation and 17% by predation. An optimum clutch elevation range for leatherback turtles was identified, where a distinct increase in hatching success was observed between -0.286 m to -0.0528 m above the HTL. For green sea turtles, 64% of experimental nests were affected by predation, confounding conclusions about the roles of environmental characteristics in green turtle hatching success. We propose further investigation into influential characteristics in green turtle nests and confirmation of the observed optimum elevation range on Bioko Island and other nesting grounds. Identified sensitivities of each species to SLR and beach characteristics will be used to encourage the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations when planning for future coastal development.

COCCIDIAL INFECTION OF THE ADRENAL GLANDS OF LEATHERBACK SEA TURTLES (DERMOCHELYS CORIACEA)

2016 ◽  
Vol 52 (4) ◽  
pp. 874-882 ◽  
Author(s):  
Sara D. Ferguson ◽  
James F. X. Wellehan ◽  
Salvatore Frasca ◽  
Charles J. Innis ◽  
Heather S. Harris ◽  
...  
Keyword(s):  
Adrenal Glands ◽  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Coccidial Infection ◽  
Leatherback Sea Turtles

Tursiocola neliana sp. nov (Bacillariophyceae) epizoic on South African leatherback sea turtles (Dermochelys coriacea) and new observations on the genus Tursiocola

Phytotaxa ◽  
2020 ◽  
Vol 453 (1) ◽  
pp. 1-15 ◽  
Author(s):  
ROKSANA MAJEWSKA
Keyword(s):  
Sea Turtles ◽  
Central Area ◽  
Sea Turtle ◽  
Dermochelys Coriacea ◽  
Eastern Coast ◽  
New Taxon ◽  
Freshwater Turtles ◽  
Diatom Genus ◽  
Leatherback Sea Turtles ◽  
Internal Side

Tursiocola, a presumably exclusively epizoic diatom genus, comprises species found on various aquatic animals such as cetaceans, manatees, and marine and freshwater turtles. The genus is characterised by linear or lanceolate valves with well-developed pseudosepta at both poles, a valvocopula with three pairs of siliceous tabs, and a butterfly-like structure extending from the central nodule on the internal side of the valve. The current study describes a novel species of Tursiocola, T. neliana Majewska sp. nov. that grows epizoically on leatherback sea turtles from the Eastern Coast of South Africa based on detailed observations using light and scanning electron microscopy. The new taxon resembles the other currently known sea turtle-associated Tursiocola species in possessing relatively small, slightly heteropolar valves with acute apices and a strongly reduced butterfly structure on the internal side. However, T. neliana differs from all other members of the genus in being distinctly dorsiventral, with a clearly bowtie-shaped central area, unequal stria density on two sides of the raphe-sternum, and up to 8 areolae per stria. The description of the new taxon brings the total number of the sea turtle-associated Tursiocola species known so far up to four. An emended description of Tursiocola is proposed based on the new observations presented in this and other recent reports. Furthermore, the current understanding of the genus ecology is summarised.

scholarly journals Behaviour of leatherback sea turtles, Dermochelys coriacea , during the migratory cycle

2005 ◽  
Vol 272 (1572) ◽  
pp. 1547-1555 ◽  
Author(s):  
Michael C James ◽  
Ransom A Myers ◽  
C. Andrea Ottensmeyer
Keyword(s):  
Sea Turtles ◽  
Satellite Telemetry ◽  
Biological Significance ◽  
Dermochelys Coriacea ◽  
Behavioural Patterns ◽  
Nesting Behaviour ◽  
Migratory Cycle ◽  
Leatherback Sea Turtles ◽  
Migratory Patterns ◽  
Nesting Beaches

Leatherback sea turtles, Dermochelys coriacea , undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.

Field anaesthesia of leatherback sea turtles (Dermochelys coriacea)

2007 ◽  
Vol 161 (1) ◽  
pp. 15-21 ◽  
Author(s):  
C. A. Harms ◽  
S. A. Eckert ◽  
S. A. Kubis ◽  
M. Campbell ◽  
D. H. Levenson ◽  
...  
Keyword(s):  
Sea Turtles ◽  
Dermochelys Coriacea ◽  
Leatherback Sea Turtles

scholarly journals Maternal Health Status Correlates with Nest Success of Leatherback Sea Turtles (Dermochelys coriacea) from Florida

PLoS ONE ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. e31841 ◽  
Author(s):  
Justin R. Perrault ◽  
Debra L. Miller ◽  
Erica Eads ◽  
Chris Johnson ◽  
Anita Merrill ◽  
...  
Keyword(s):  
Health Status ◽  
Maternal Health ◽  
Sea Turtles ◽  
Nest Success ◽  
Dermochelys Coriacea ◽  
Leatherback Sea Turtles
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