Resting eggs in a key player Calanoid copepod in coastal areas. The case of Acartia tonsa (Dana)

 

Acartia tonsa is an invasive copepod of the European coastal waters, first described in France in 1926, it was found later in most of the European coastal areas. These invasions are believed to come from transport of resting eggs in ships ballast water. In this presentation, I will show the main results of 7 years of experimental work which allowed us to understand better the capacity of A. tonsa to produce resting eggs. A.tonsa has a double resting strategy, part of it is due to the capacity of the subitaneous eggs to switch to quiescence under unfavorable environmental conditions which allows the eggs to wait partially optimum conditions to hatch. Also some population of A. tonsa are capable of producing real diapauses eggs (or delayed hatching eggs) which are developed as a single winter based strategy and have to endure a refractory phase before hatching. Our recent findings show that food availability could trigger the production of diapause eggs even under optimal light and temperature conditions.