Reproductive Dynamics of Scoletoma Laurentiana (Polychaeta: Lumbrineridae) in NW Spain: Temperature-Driven Seasonal Trends

Abstract

[Abstract] Understanding reproductive cycles is essential for the sustainable management of marine resources, particularly those of exploited yet understudied invertebrates such as the polychaete Scoletoma laurentiana, a key bait species in Galicia (NW Spain). This study provides the first detailed description of its reproductive cycle in temperate Atlantic waters, focusing on seasonal dynamics and environmental drivers. Monthly samples collected during 2021 and 2023 at three coastal sites were analyzed through image-based quantification of oocyte size in relation to seawater temperature and photoperiod. The results revealed synchronous oogenic development at the individual level but asynchronous at the population scale, indicating extended spawning periods. Oogenesis began in late autumn, peaked in spring, and ceased completely during summer. Overall mean oocyte diameter was 172.27 μm ± 22.52, with significant spatial and interannual differences indicating reproductive plasticity. A strong inverse correlation between seawater temperature and the proportion of ovigerous females confirmed temperature as the main driver of spawning initiation, whereas photoperiod showed no significant effect. These findings provide the first comprehensive evidence of temperature-mediated reproductive seasonality in S. laurentiana, offering critical baseline knowledge for the sustainable management of this species in the northeastern Atlantic. Furthermore, the results indicate that the species productivity may be subject to alteration in response to climate change.