Embryonic and larval development of the brown wrasse Labrus merula (Pisces: Labridae)

In March 1997 one male and one female brown wrasse Labrus merula spawned sp ontaneously in aquaria conditions. Eggs were incubated at ambient temperatu re, salinity oxygen and pH. The development of the eggs, yolk-sac larvae an d larvae is described and illustrated with particular emphasis on features of practical value for identification of specimens from plankton. The ripe egg of brown wrasse is a typical labrid egg with a mean diameter of 0.93 +/ - 0.05 mm. The incubation period was 106 h 45 min at a mean temperature of 14.3 degrees C. Newly hatched yolk-sac larvae were 3.8 +/- 0.02 mm, while t he yolk-sac was resorbed when larvae reached 4.68 +/- 0.15 mm in total leng th. Some characteristics which may be useful for identification are describ ed and compared with some other labrid yolk-sac larvae and larvae. The leng th of newly hatched yolk-sac larvae of brown wrasse was significantly large r (t-test, P<0.05) than those of the other labrid species, but it is simila r to that of Labrus bergylta. During the first 16 d (after resorption of yo lk-sac) brown wrasse larvae does not possess a double crescent of melanopho res on top of the head, but has a few melanophores on the anal fin which is very similar to the pigmentation of Symphodus (Crenilabrus) melops larvae, although there is a difference in length between them. Larvae older than 1 6 d have a double crescent of melanophores on the top of the head with mela nophores on the anal fin-fold identical to L. bergylta larvae, but the diff erence in larvae length also exists.