Effect of temperature on interactions between eggs and spermatozoa in four closely related species of sea urchins of the genusEchinometra

Abstract

Sea urchins of the genus Echinometra are abundant on reef flats in southern Japan. The Okinawan Echinometra is divided into four sympatric and closely related species, Echinometra tsumajiroi (Ea), Echinometra mathaei (Eb), Echinometra ryukyuensis (Ec), and Echinometra oblonga (Ed). To obtain further information of these four species, this study examined the effect of temperature on the interactions between eggs and spermatozoa. Fertilization in all four Echinometra species showed marked temperature dependence. Temperatures above 15EC were required for fertilization and fertilization was virtually zero at temperatures below 10EC. Furthermore, the acrosome reaction of spermatozoa in Ea, Eb, Ec and Ed induced by egg-jelly was influenced by temperature. The acrosome reaction hardly occurred at 0EC in the four species, and the proportion of reactive spermatozoa treated with sea water containing egg-jelly increased with temperature to a maximum at 20EC but was lower at 30EC. The study did not reveal any substantial temperature-related differences in fertilization and acrosome reaction between the four species. These results suggest that, even though Okinawan Echinometra are considered to be four independent species, their divergence has apparently taken place quite recently.

Fertilization, post-fertilization development and larval biology of the South African polychaete,Arenicola loveni loveni(Kinberg 1866)

“…Temperature has also been shown to significantly affect fertilization (Rupp, 1973;Andronikov, 1975;Mita et al, 1984;Levitan, 2000;Lewis, 2002;Lewis et al, 2002) and post-fertilization development (Lewis, 2002;Ushakova, 2003) in a number of species. It has been demonstrated that seawater temperature significantly affects fertilization success in A. marina, with the maximum fertilization success recorded at temperatures of 15-18EC, which is higher than the ambient seawater temperature at the time of spawning (Lewis et al, 2002).…”

Effects of Environmental Stressors on the Early Development of Intertidal and Subtidal Gastropod Embryos

“…Temperature can also increase rapidly, particularly on summer days when low tides coincide with high midday temperatures (Trowbridge, 1994;Podolsky, 2000). Temperature has been shown to play an important part in early life stages, including embryonic development in invertebrate egg masses (Przeslawski, 2004;Mita et al 2007). Gastropod embryos have been suggested to be more able to tolerate low temperatures than high temperature extremes (Przeslawski, 2004) and may be extremely vulnerable to high temperature during their embryonic life stage (Thorson, 1950).…”