Effects of photoperiod on egg production in Eurytemora affinis Poppe, 1880 (Copepoda: Calanoida) from the Seine Estuary (France)

Research on the calanoid copepod Eurytemora affinis in the Seine Estuary reveals that short photoperiods (≤12 hours of light) and constant darkness can induce diapausing egg production, with a maximum of 6% observed under these conditions. This finding suggests that E. affinis, a key species in the estuary's mesozooplanktonic community, employs an egg bank strategy for long-term survival or adverse condition resilience. The study used an experimental device combining five photoperiods and two temperatures to assess diapausing egg production across two clutches, also noting a significant increase in non-viable eggs between clutches. While photoperiod is a key factor, other environmental variables likely influence this reproductive strategy. The observed diapausing egg percentage (7%) aligns with natural sediment samples from the estuary, supporting the hypothesis of an adaptive survival mechanism.

Glippa, O., Alekseev, V. R., & Souissi, S. (2013). Effects of photoperiod on egg production in Eurytemora affinis Poppe, 1880 (Copepoda: Calanoida) from the Seine Estuary (France). Italian Journal of Zoology, 80(4), 518–525. https://doi.org/10.1080/11250003.2013.861024