Meeting Abstract
Surfing onto shore on moonlit nights, California Grunion Leuresthes tenuis completely emerge from water during spectacular spawning runs to deposit their eggs on sandy shores of southern California. This endemic species may be particularly vulnerable to effects of climate change on reproduction because of its beach-spawning habits. Not only must the adults cope with changing water temperatures, but the embryos require oviposition on sandy beaches and develop out of water. Remaining in the sand until triggered to hatch by rising tides, the embryos may be affected by rising air temperatures as well. Because of this unusual life history, L. tenuis may be a key indicator of the early effects of climate change, as it is already showing effects of ocean warming. The spawning runs reported recently may be less extensive in traditional habitat range of southern California than in the past. New spawning runs have been observed farther north, where this species never occurred previously. For L. tenuis in San Francisco Bay and more northern areas, adults grow to a smaller adult size, produce smaller and fewer eggs, reproduce less frequently, and live shorter lives than their southern counterparts. This makes them more vulnerable to short-term local disturbances and local extirpation. Thus a habitat shift more northward may lead to changes in reproduction and life history in this species that may not be as sustainable over the long term for populations as those in traditional habitats are.
