The reproductive cycle of the sea urchin Arbacia lixula in northwest Mediterranean: potential influence of temperature and photoperiod

Abstract

21 22We studied the reproductive cycle of the sea urchin Arbacia lixula in a subtidal population from 23Northeast Spain over four years using a gonadosomatic index and gonad histology. Our results 24show that the gonadosomatic index of A. lixula follows a seasonal cycle which peaks in May-July 25 and attains its lowest values in October-November every year. The time course of the 26 gonadosomatic index matched closely the photoperiod cycle. We also found a remarkable inter-27 annual variability in the maximum value of gonadosomatic index, which correlated with mean 28 water temperature during the gonad growth period (winter and spring). Gonad histology was also in 29 agreement with a single gametogenic cycle per year in this species. We explored the application of 30 circular statistics to present and analyse gonadal development data, which allowed us to adequately 31 handle the high intra-individual variability detected, with several developmental stages commonly 32 found within the same gonad. The picture that emerged is one of a gametogenic timing driven by 33 photoperiod, while the amount of reproductive output is determined by temperature. This is 34 coherent with the tropical origin of the species and lends support to recent warnings about an 35 increase in the abundance of this species in the Mediterranean as a result of global warming, with 36 associated increased impact potential in sublittoral communities. 37 38 Introduction 39

Efficiency of artificial collectors for quantitative assessment of sea urchin settlement rates

“…The lack of A. lixula settlers in Tossa de Mar during the sampling period proves that the settlement timings of the two species studied are far from being synchronized in the Mediterranean Sea, unlike in the Canary Islands. A probable explanation for this asynchrony is the reduced survival of A. lixula larvae in the cold water temperatures prevailing in the Mediterranean during the spring months (Wangensteen et al 2013a), which would prompt the adult populations of this sea urchin to spawn during the summer season (Wangensteen et al 2013b). However, further sampling experiments are needed in order to investigate the settlement behaviour of A. lixula in the northwestern Mediterranean.…”

“…A rich cover of photophilous algae, such as Dictyota dichotoma, Stypocaulon scoparium, Padina pavonica and Corallina elongata (Wangensteen et al 2011), and the absence of barren zones allow A. lixula and P. lividus to dwell on these bottoms in moderate densities, reaching up to 1.1 and 3.3 individuals m -2 , respectively (Wangensteen et al 2013b). …”

Photoperiod, temperature, and food availability as drivers of the annual reproductive cycle of the sea urchin Echinometra sp. from the Gulf of Aqaba (Red Sea)

“…Chi-squared tests were used to test possible differences in sex ratios. Differences in GSI were evaluated following Wangensteen et al (2013); Mann-Whitney U tests were applied to test for between-sexes differences for every month (p values corrected for multiple testing using the Benjamini and Yekutieli FDR correction;Benjamini and Yekutieli 2001). As no significant differences were found, both sexes were pooled for further analyses.…”

“…In that sense, the environmental variables that regulate reproduction in sea urchins have been a subject of interest ever since the notion was posited that invertebrates reproduce during restricted annual periodicities (Orton 1920;Giese and Pearse 1974). The remarkable natural fluctuations exhibited by some echinoderm species (Uthicke et al 2009) are often associated with regulation of their reproductive processes by environmental factors (Wangensteen et al 2013). Thus, elucidating the potential environmental factors that regulate sea urchin reproduction greatly contributes to our ability to assess and predict the future of these prominent reef-structuring organisms, in particular in the context of climate change and the continuous increase in anthropogenic perturbations to the marine environment.…”

Studies on the Influence of Abiotic Factors in the Gonadal Index of Sea urchin Salmacis virgulata from the Gulf of Mannar, South East Coast of India

“…A total of 600 individuals of sea urchin Salmacis virgulata were collected during the 20 month period from October 2013 to May 2015 and the differences in mean GSI were evaluated 9 . The data on the Sea surface temperature and atmospheric temperature was obtained from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) 10 for the period of 20 months since October -2013 to May-2015.…”