TEMPORAL STABILITY OF IN VITRO VENOUS BLOOD GAS, pH, AND LACTATE VALUES OF COWNOSE RAYS (RHINOPTERA BONASUS) AND RED-EARED SLIDER TURTLES (PSEUDEMYS SCRIPTA ELEGANS).

This study assessed the in vitro temporal changes that occur in blood pH and lactate concentrations for an elasmobranch species and a chelonian species, as well as blood gases (partial pressures of carbon dioxide [pCO2] and oxygen [pO2]) for a chelonian species, with a portable clinical point-of-care analyzer. Blood samples were collected from 10 cownose rays (Rhinoptera bonasus) and 10 red-eared sliders (Pseudemys scripta elegans), stored on ice, and serially analyzed at six time points up to 90 min postcollection. Results indicate that analysis should be conducted as soon as possible after blood collection for these species, with immediate analysis being preferred. However, if analysis must be delayed, syringes may be capped, placed on ice, and analyzed at a later time. Analysis within 90 min provided clinically acceptable results for pH and lactate in both species and for pCO2 in red-eared sliders, whereas substantial artifactual increases of pO2 were seen in red-eared sliders.

Long-term use of a shark breeding ground: Three decades of mating site fidelity in the nurse shark, Ginglymostoma cirratum.

Understanding shark mating dynamics and mating site use may be vital to species management. The Dry Tortugas courtship and mating ground (DTCMG) has been known as a mating site for nurse sharks, Ginglymostoma cirratum, since 1895. In a 30-yr (1992-2021) study we have documented long-term site fidelity to this area with data from 137 adult sharks (89 female, 48 male) tagged with PIT, fin, and acoustic tags. Of 118 sharks tagged from 1993 to 2014, at least 80 (68%) returned to the DTCMG in subsequent years during the June-July mating season. Known individuals returned in up to 16 different mating seasons and over periods of up 28 years, indicating that life span extends well into the forties for this species. Of all returning sharks, 59% (N = 47) have been monitored for over 10 years and 13% (N = 10) have been monitored for over 20 years. Males arrived annually in May and June and departed in July, whereas females arrived biennially or triennially in June, with a secondary peak in site use in September and August, likely associated with thermoregulation during gestation. During the mating season, males made more frequent visits of shorter duration (median = 34 visits for 1 h per visit) to the DTCMG, whereas females made fewer visits but remained on site for longer periods (median = 12.5 visits for 4.4 h per visit). Females typically mated biennially but showed a triennial cycle in 32% of cases, with many females switching cycles at least once. This pattern would reduce the potential reproductive lifetime output of a female by 11% compared to what would be projected from a strict biennial cycle. The long-term mating site fidelity of this shark population reveals the importance of identifying and protecting mating sites for this and other elasmobranch species.