Physiological determinants of the internesting interval in sea turtles: a novel ‘water-limitation’ hypothesis

Abstract

The internesting interval separates successive clutches of sea turtle eggs, and its duration varies both among and within species. Here, we review the potential physiological limits to this interval, and develop the hypothesis that desalination capacity limits the internesting interval owing to the requirement for water deposition in eggs. Sea turtles deposit 1–4 kg of water per clutch in egg albumen; for most species, this represents about 2% of adult body mass. We calculate how quickly turtles can recover this water by estimating maximal salt excretion rates, metabolic water production and urinary losses. From this water balance perspective, the ‘water-limitation’ hypothesis is plausible for green turtles but not for leatherbacks. Some plasma biochemistry studies indicate dehydration in sea turtles during the nesting season, although this is not a universal finding and these data have rarely been collected during the internesting interval itself. There is mixed support for a trade-off between clutch size and the length of the interval. We conclude that the ‘water-limitation’ hypothesis is plausible for most sea turtle species, but requires direct experimentation.

Plasma electrophoresis profiles of Blanding’s turtles (Emydoidea blandingii) and influences of month, age, sex, health status, and location

“…Alternatively, the increased gamma globulin concentration in May could be secondary to vitellogenesis, as the release of estrogen stimulates hyperglobulinemia in chelonians [ 55 , 56 ]. Elevated albumin concentrations in June may be attributable to dehydration associated with prolonged overland trips and nesting-associated exertion, similar to previous reports in sea turtle species [ 48 , 57 – 59 ]. Studies in other chelonian and lizard species have documented elevations in albumin and total proteins during the summer months and have correlated these elevations to the increased food consumption and reproductive activity in this time period [ 4 , 60 , 61 ].…”

Health and nutrition of loggerhead sea turtles (Caretta caretta) in the southeastern United States

“…Sick loggerheads also displayed relatively higher tWBC, heterophil, and lymphocyte counts, possibly due to antigenic stimulation from infection, and higher CO 2 which may be related to poor ventilation associated with respiratory distress such as caused by stranding or pneumonia (Hunt et al, 2016). Loggerhead sea turtles are capital breeders, mostly ceasing to feed during reproduction, and some differences in blood analytes observed for nesting loggerheads are indicative of reduced foraging, such as plasma concentrations of BUN and creatinine that were even lower than those of sick loggerheads in this study (Perrault & Stacy, 2018; Price et al, 2019). These differences highlight the need to develop baseline blood parameter reference intervals that are specific to the life history stage, which can be applied in a rehabilitation setting to help interpret clinical data for stranded loggerheads in various physiological states.…”

Using Data from Satellite Telemetry and Nesting Beach Monitoring to Improve Estimates of Marine Turtle Clutch Frequency

“…the turtles may select shallow warmer waters for breeding residence (see Fossette et al, 2012;Scho eld et al, 2009). Also linked to physiology, the water limitation hypothesis has been suggested to in uence the length of internesting interval (Price et al 2019). Indeed, rehydration was theoretically suggested as responsible for mass recovery during the internesting interval (Santos et al 2010) when gravid hawksbill turtles are fasting (Goldberg et al 2013).…”