TY - JOUR
T1 - Sexually unbalanced gonad development and nutrition of the newly range-extended sea urchin Heliocidaris crassispina in the northeastern Honshu, Japan
AU - Feng, Wenping
AU - Nakabayashi, Nobuyasu
AU - Inomata, Eri
AU - Aoki, Masakazu N.
AU - Agatsuma, Yukio
N1 - Funding Information:
We appreciate the support of Prof. M. Osada in Laboratory of Aquacultural Biology of Tohoku University for the histological analysis and Associate Prof. K. Ito in the Laboratory of Fisheries Biology and Ecology of Tohoku University for C/N analyses. We sincerely thank A. Nakamura, the former Director General of the Akita Prefectural Institute of Fisheries, for his cooperation with this research. We are grateful to the staff of the Toga Branch of the Akita Fisheries Cooperative Association for their support in sea urchin collection.
PY - 2021/2/5
Y1 - 2021/2/5
N2 - Ocean warming is increasingly recognized as a leading environmental risk to marine organisms. This phenomenon has led to poleward range extension of the sea urchin Heliocidaris crassispina to Toga Bay along the Oga Peninsula in Japan since 2014. Observations of H. crassispina gonads in maturation–spawning stages suggested delayed spermatogenesis in the new habitats. To determine the effects of ocean warming on H. crassispina, particularly to verify the delay in spermatogenesis and identify its specific cause, we investigated the seasonal changes in gonad development in relation to temperature and the associated carbon and nitrogen contents of the gonad and gut tissues and the gut contents to evaluate the nutritional status of the newly range-extended sea urchins by sex. Heliocidaris crassispina showed a defined gametogenic cycle with a single spawning per sex. The sex ratio was skewed to females (1.27:1). Males exhibited growing gonads during February–May, while females exhibited recovering gonads during February–April. Spermatogenesis was delayed one month compared to oogenesis. Spawning was partially synchronized between the sexes from August to September. A long-term warming trend in annual average and May–August in Toga Bay indicates that H. crassispina is subjected to the low temperature, particularly during winter in new habitat. The carbon/nitrogen (C/N) ratios were lower in the testes than in the ovaries regardless of no sexual differences in the gut from February to October. Although higher total protein content in testes than that of ovaries is required from the recovery to growing stages, N content of gonad showed no significantly sexual difference, suggesting that insufficient protein accumulation in testes suppress spermatogenesis that would be the possible factor of delayed spermatogenesis and partially synchronized spawning between sexes. Female-skewed sex ratio and delayed spermatogenesis suggest the lower possibility of self-reproduction in the newly extended population.
AB - Ocean warming is increasingly recognized as a leading environmental risk to marine organisms. This phenomenon has led to poleward range extension of the sea urchin Heliocidaris crassispina to Toga Bay along the Oga Peninsula in Japan since 2014. Observations of H. crassispina gonads in maturation–spawning stages suggested delayed spermatogenesis in the new habitats. To determine the effects of ocean warming on H. crassispina, particularly to verify the delay in spermatogenesis and identify its specific cause, we investigated the seasonal changes in gonad development in relation to temperature and the associated carbon and nitrogen contents of the gonad and gut tissues and the gut contents to evaluate the nutritional status of the newly range-extended sea urchins by sex. Heliocidaris crassispina showed a defined gametogenic cycle with a single spawning per sex. The sex ratio was skewed to females (1.27:1). Males exhibited growing gonads during February–May, while females exhibited recovering gonads during February–April. Spermatogenesis was delayed one month compared to oogenesis. Spawning was partially synchronized between the sexes from August to September. A long-term warming trend in annual average and May–August in Toga Bay indicates that H. crassispina is subjected to the low temperature, particularly during winter in new habitat. The carbon/nitrogen (C/N) ratios were lower in the testes than in the ovaries regardless of no sexual differences in the gut from February to October. Although higher total protein content in testes than that of ovaries is required from the recovery to growing stages, N content of gonad showed no significantly sexual difference, suggesting that insufficient protein accumulation in testes suppress spermatogenesis that would be the possible factor of delayed spermatogenesis and partially synchronized spawning between sexes. Female-skewed sex ratio and delayed spermatogenesis suggest the lower possibility of self-reproduction in the newly extended population.
KW - C/N ratio
KW - Gonad development
KW - Heliocidaris crassispina
KW - Range extension
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U2 - 10.1016/j.ecss.2020.107120
DO - 10.1016/j.ecss.2020.107120
M3 - Article
AN - SCOPUS:85097203268
VL - 249
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
SN - 0272-7714
M1 - 107120
ER -