Biomedical subjects

Richard D Reina

Publications and source records attributed to Richard D Reina.

4 recordsLinked to original sources

PubMed2006

Ontogeny of energetics in leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) sea turtle hatchlings.

Changes in activity related oxygen consumption were measured in leatherback and olive ridley sea turtle hatchlings over their first month after emergence from the nest. Leatherbacks emerged with 75-90 KJ of energy in the residual yolk for growth and activity whereas olive ridleys emerged with 45 KJ. In leatherbacks (n=8), resting mass-specific oxygen consumption rates decreased by 53% over the first post-hatching month (0.34+0.03 mL O(2) h(-1) g(-1) to 0.16+0.01 mL O(2) h(-1) g(-1), respectively), while for ridleys (n=8) the fall was 35% (0.20+0.03 mL O(2) h(-1) g(-1) to 0.13+0.01 mL O(2) h(-1) g(-1), respectively). Olive ridley factorial aerobic scope doubled (1.93+0.30 to 3.97+0.51) over the first month but there was no significant increase in leatherback factorial aerobic scope (1.39+0.21 to 1.60+0.13). Leatherback hatchlings gained on average 20% initial body mass (7.68+1.66 g) over the first week, with 70 to 80% of this increase due to water accumulation. Olive ridleys gained 14% (1.83+0.16 g) in initial mass over the first week of age. We propose that the differences in aerobic scope and energy reserves are related to differences in early life ecological stratagems of these species.

Aerobiosis↗

PubMed2006

Egg components, egg size, and hatchling size in leatherback turtles.

Relationships between egg size, egg components, and neonate size have been investigated across a wide range of oviparous taxa. Differences in egg traits among taxa reflect not only phylogenetic differences, but also interactions between biotic (i.e., maternal resource allocation) and abiotic (i.e. nest environment conditions) factors. We examined relationships between egg mass, egg composition, and hatchling size in leatherback turtles (Dermochelys coriacea) because of the unique egg and reproductive characteristics of this species and of sea turtles in general. Albumen comprised 63.0%+/-2.8% (mean+/-S.D.) of egg mass and explained most of the variation in egg mass, whereas yolk comprised only 33.0%+/-2.7%. Additionally, leatherback albumen dry mass was approximately 16% of albumen wet mass. Whereas hatchling mass increased significantly with egg mass (n = 218 clutches), hatchling mass increased by only approximately 2 g for each 10 g increase in egg mass and was approximately 10-20 g greater than yolk mass. Taken together, our results indicate that albumen might play a particularly significant role in leatherback embryonic development, and that leatherback eggs are both capable of water uptake from the nest substrate and also possess a large reservoir of water in the albumen. Relationships between egg mass and egg components, such as variation in egg mass being largely explained by variation in albumen mass and egg mass containing a relatively high proportion of albumen solids, are more similar to bird eggs than to eggs of other non-avian reptiles. However, hatchling mass correlates more with yolk mass than with albumen mass, unlike patterns observed in bird eggs of similar composition.

Animals↗

PubMed2002

Salt and water regulation by the leatherback sea turtle Dermochelys coriacea.

We measured the salt and water balance of hatchling leatherback sea turtles, Dermochelys coriacea, during their first few days of life to investigate how they maintain homeostasis under the osmoregulatory challenge of a highly desiccating terrestrial environment and then a hyperosmotic marine environment. Hatchlings desiccated rapidly when denied access to sea water, with their hematocrit increasing significantly from 30.32+/-0.54 % to 38.51+/-1.35 % and plasma Na(+) concentration increasing significantly from 138.2+/-3.3 to 166.2+/-11.2 mmol l(-1) in 12 h. When hatchlings were subsequently put into sea water, hematocrit decreased and plasma Na(+) concentration was unchanged but both were significantly elevated above pretreatment values. In other hatchlings kept in sea water for 48 h, body mass and plasma Na(+) concentration increased significantly, but hematocrit did not increase. These data show that hatchlings were able to osmoregulate effectively and gain mass by drinking sea water. We stimulated hatchlings to secrete salt from the salt glands by injecting a salt load of 27 mmol kg(-1). The time taken for secretion to begin in newly hatched turtles was longer than that in 4-day-old hatchlings, but the secretory response was identical at 4.15+/-0.40 and 4.13+/-0.59 mmol Na(+) kg(-1) h(-1) respectively. Adrenaline and methacholine were both potent inhibitors of salt gland secretion in a dose-dependent manner, although methacholine administered simultaneously with a subthreshold salt load elicited a transient secretory response. The results showed that hatchling leatherbacks are able to tolerate significant changes in internal composition and efficiently use their salt glands to establish internal ionic and water balance when in sea water.

Animals↗

PubMedDate not supplied

Biotic and abiotic factors affect the nest environment of embryonic leatherback turtles, Dermochelys coriacea.

Clutches of leatherback turtles, Dermochelys coriacea, have lower hatching success than those of other sea turtles, but causes of high embryonic mortality are unknown. We measured characteristics of clutches along with spatial and temporal changes in PO(2) and temperature during incubation to determine the extent to which they affected the developmental environment of leatherback embryos. Minimum PO(2) in nests decreased as both the total number and mass of metabolizing embryos increased. Increases in both the number and mass of metabolizing embryos caused an increase in maximum nest temperature. However, neither PO(2) nor temperature was correlated with hatching success. Our measurements of relatively high nest PO(2) (lowest 17.1 kPa or 16.9% O(2)) indicate that hypoxia apparently does not cause the low hatching success of leatherback clutches. Oxygen partial pressure increased and temperature decreased from the center toward the periphery of leatherback nests. We inferred from these measurements that positions of eggs within nests vary in quality and potentially affect overall developmental success of entire clutches. The large metabolic mass of leatherback clutches and limits to gas flux imposed by the sand create a situation in which leatherback embryos collectively affect their own environment.

Animals↗