Larval growth of the polychaete Arenicola marina under different temperature and food conditions: consequences on bioenergetic models

Arenicola marina, a marine benthic polychaete, is widespread on sandy beaches in Europe and considered as an ecosystem engineer despite commonly used as bait by fishermen. Data regarding the bioenergetics of the lugworm larval stages are still incomplete. Trochophore is initially lecithotroph and then becomes planktotroph while growing as metatrochophore on subtidal area, a quite stable daily temperature environment compared with the foreshore, where juveniles and adult live, with daily temperature fluctuating up to 15 degrees C. These discrepancies in temperature ranges may influence the temperature corrections (TCs) that control metabolic rates during the life cycle of A. marina. We carried out laboratory experiments in microcosms by inducing artificial spawning of lugworms, and then undertaken in vitro fertilization to obtain embryos and, finally, to follow, the larval development up to 10 segments with chaetae for 50 days under three temperature conditions (13 degrees C, 15 degrees C and 17 degrees C) and two food conditions ('fed'and 'non-fed'). The first feeding ('birth') of A. marina larvae was deciphered anatomically for a size between 450 and 500 itm and described at 17 days post-fertilization for larvae reared at 15 degrees C and 17 degrees C. Using a biphasic model with a von Bertalanffy growth before 'birth' and an exponential growth after 'birth, among the three temperature treatments, the 15 degrees C condition exhibited the best larval performance. TC based on embryonic and larval metabolic rates gave an Arrhenius temperature of similar to 6661 K and a higher boundary temperature tolerance range of similar to 294.5 K. Both temperature values differ from those calculated from TC based mostly on juvenile and adult metabolic rates. We claim to use two sets of Arrhenius temperatures according to the life history stages of A. marina while using Dynamic Energy Budget model. This model was developed initially in order to manage the conservation of the lugworm species.

Automated summary

This study found that temperature affects the metabolic rates of Arenicola marina larvae during their life cycle, with the larvae performing best at a temperature of 15 degrees Celsius.