BSP-7-7 Sun Jan 3 18:15 – 18:30 Large effect of small temperature changes on embryonic development of Antarctic invertebrates Lobert, GT*; Toh, MWA; Moran, AL; University of Hawai’i at Manoa; University of Hawai’i at Manoa; University of Hawai’i at Manoa gtlobert@hawaii.edu
The Southern Ocean surrounding Antarctica is the coldest ocean on Earth and many of the ectotherms that live there are highly stenothermal. For Antarctic fauna, few studies have investigated the effect of increasing temperature on early developmental stages; these are often more vulnerable to environmental stressors than later stages. We measured the thermal sensitivity of early cleavage of two Antarctic invertebrates, a pycnogonid (Ammothea glacialis), and a nudibranch (Tritoniella belli). Uncleaved zygotes were placed in a thermal gradient block and maintained at a range of 10 temperatures from -1.8°C (ambient) to 3.5°C until reaching at least the 16-cell stage. For both species, embryos reached the 16-cell stage in approximately half the time at the highest temperature compared to ambient (A. glacialis 16 vs. 35 d, T. belli 7 vs. 16 d). Q10 values across the whole temperature range were 6.4 for A. glacialis (n = 1 clutch) and 6.12±0.4 for T. belli, (n = 3 clutches), indicating high thermal sensitivity of early cleavage. Arrhenius plots showed no change in the thermodynamics of cleavage over the temperature range for 3 of the 4 trials. For one set of T. belli, development failed completely at and above 2.9°C; in all trials, abnormalities and mortality were more frequent at the higher temperatures. These data indicate that early cleavage rates of two Antarctic species are highly sensitive to increases in temperature, but also that there is considerable variation in embryos’ ability to develop normally at temperatures > 4°C degrees above ambient. Funded by NSF-OPP-1745130 to ALM
