Effect of food limitation and temperature on survival and development of Hemigrapsus sanguineus first stage larvae

This is a laboratory experiment, carried out in Helgoland to explore how responses to the time scale and magnitude of fluctuations in environmental variables depend on the choice of time reference frame. The experiment consisted of exposing larvae of an intertidal invertebrate, Hemigrapsus sanguineus to different initial feeding periods (in days; food = freshly hatched Artemia sp Nauplii provided ad libitum), followed by a period without food. An ovigerous female of H. sanguineus was collected by hand in the intertidal of Helgoland (SW beach: “Kringel”; coordinates: 54.177323°N, 7.885273°E) during low tide on the 15th October 2020. It was kept until larval hatching in an aquarium (vol = 2 L with a shelter) at salinity = 32 ppt, temperature = 18°C, photoperiod 12:12, permanent oxygenation and fed every second day (from frozen shrimp); water was changed every day. Experiments started on date 31st October 2020 (day 0 of the feeding period). The feeding protocol was carried out with groups of freshly hatched zoea I larvae (3 replicates of 10 larvae each) at 4 temperatures (15, 17, 19, 21°C). Larvae were reared at salinity = 32 ppt. The response variables were developmental time (in days) and the number of larvae reaching the second zoeal stage. Additional columns provide calculations of the average duration of development depending on temperature and the proportion of feeding time given as a proportion of the full developmental time.