Effects of environmental stressors on blood-glucose levels in sea hares, Aplysia dactylomela

Abstract

Abstract. Effects of natural stressors such as tidepool strandings, air exposure, and low salinity on blood-glucose levels were investigated in the sea hare Aplysia dactylomela from shallow areas of Discovery Bay, Jamaica. All treatments produced large and significant elevations in blood-glucose titre, 1.5-to 2.3-fold above baseline levels of 25 to 35 gg glucose ml-1. Response times were variable, with significant elevations being manifested within 30 to 120 min from initiation of the stressor. Recovery was swift, within an hour or two of restoration to pretreatment conditions, and often involved an undershoot to levels below control values. In two experiments involving tidepool strandings and associated high body-temperatures, excessively low blood-glucose titres were followed by death of all test individuals. When sea hares were exposed to 75 and 50% seawater (100% = 33%o S) for 1 h, maximum elevation in blood-glucose concentrations occurred I to 2 h from onset of exposure, coincidental with maximum dilution of the body fluids of test individuals. The responsiveness of blood-glucose titres to relatively small temperature or salinity changes, or to short-duration air exposures, suggests that monitoring this physiological parameter may be a useful and sensitive means of diagnosing a wide variety of stressors in marine gastropods.

Stress and immune responses in abalone: Limitations in current knowledge and investigative methods based on other models

“…Glucose levels in the haemolymph of H. laevigata rise after exercise stress and in response to increasing temperature [43]. This is consistent with findings on the heterobranch molluscs Aplysia dactylomela [44,45] and A. californica [46]. Haldane [43] found no concurrent drop in the glycogen levels during exercise stress, suggesting that this activity is supported by aerobic metabolism, in contrast to Baldwin et al [47], who reported reduced glycogen levels after exercise in H. iris, and that anaerobic glycolysis in H. iris also results in the production of lactate and a concomitant fall in the pH.…”

NMR-based metabolomics using earthworms as potential indicators for soil health

“…In fish, a similar blood glucose response is observed due to acute stress caused by transport, handling, netting and confinement (Kubįay and Uluköy 2002), lice infestation (Mustafa et al 2000) and elevated temperatures . Glucose in crustaceans can be elevated in response to heavy metals (Lorenzon et al 2000) and in sea hares due to atmospheric exposure (Carefoot 1994). Similarly, when subjected to freezing stress worm extracts display elevated glucose levels, the levels of which varied according to species and freeze-tolerance (Bundy et al 2003).…”

Analysis of the physiological responses of Pacific abalone (Haliotis discus hannai) to various stressors to identify a suitable stress indicator

“…In aquatic animals facing stress, glycogen degradation and glucose uptake can be accelerated to provide more energy for damaged cells (Lin et al, 2018). Several studies have shown that glucose levels can be used to assess stress responses in mollusks, including abalone (Carefoot, 1994; Haldane, 2002; Hooper et al, 2007). As elevated hemolymph glucose levels are a common stress response in marine invertebrates, metabolic markers including plasma glucose can generally be used to assess stress status in abalone (Chen et al, 2023).…”