Early life history of the pipe¢sh Nerophis lumbriciformis (Pisces: Syngnathidae) N.M. Monteiro* O$ , V.C. Almada P and M.N. Vieira* O *Departamento de Zoologia e Antropologia, Faculdade de Cie“ ncias da Universidade do Porto, Prac° a Gomes Teixeira, 4099-002 Porto, Portugal. O CIIMARöCentro Interdisciplinar de Investigac° a‹ o Marinha e Ambiental, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal. P Instituto Superior de Psicologia Aplicada, Rua Jardim do Tabaco,44, 1149-041 Lisboa, Portugal. $ Corresponding author, e-mail: nmonteir@fc.up.pt The embryonic and larval development of the pipe¢sh Nerophis lumbriciformis is described. The full devel- opment sequence lasted 30 d (at 14^158C), being shortened to 25^26d at higher temperatures (16^178C), and hatching occurred throughout a 2^3d period. Unlike species of the genus Syngnathus, the newly hatched larvae presented a functional mouth apparatus and the yolk sac completely absorbed. INTRODUCTION The family Syngnathidae (pipe¢shes and seahorses) is characterized by especially pronounced adaptations for male parental care, with the female depositing eggs directly on a specialized incubation area or brood pouch on the tail or trunk of the male (Herald, 1959). This particular mode of reproduction, together with the presence of sex role reversal in some syngnathid species (Berglund et al., 1986; Vincent et al., 1992), has converted this family to an exceptional model for the study of sexual selection. Nerophis lumbriciformis Jenyns (1835) is a small and slender pipe¢sh, found on the rocky intertidal to about 30 m, usually among seaweeds at high tide or under- neath loose stones during the ebb tide, where it feeds on small crustaceans (Monteiro et al., 2001). Its distribution ranges from the Atlantic coast of Norway to the Kattegat and from Belgium southwards to Morocco (Dawson, 1986). Although locally common, the reproductive ecology of this species is still poorly known. Based on several successful spawnings that occurred in aquaria, the embryonic and larval development of this pipe¢sh is described. MATERIALS AND METHODS Eggs were obtained both from captive males that underwent pregnancy in aquaria as well as from wild specimens collected at Viana do Castelo (northern Portugal). Captive ¢sh were fed daily with fresh Artemia nauplii. Tanks (90l) were illuminated with £uorescent lights (18 W) with a photoperiod of 13L:11D. Due to the ‘gas bubble disease’, common in pipe¢sh, aeration was performed in an external tank connected to the used aquaria. The circulating seawater temperature was main- tained constant at two di¡erent temperatures, 14^158C and 16^178C. The bottom of the tank was covered with sand, boulders forming several holes and crevices, and algae. Once spawning had occurred, eggs were carefully removed from the male’s ventral surface with the aid of pincers, with a daily periodicity (except during the ¢rst day, when the egg extraction occurred several times). Eggs were immediately preserved in bu¡ered 5% formalin, and observed under a Leica stereomicroscope attached to a digital video camera. The embryos were removed from the eggs and digitalized images were taken to allow subsequent description of the several stages of development. Figure 1 summarizes a sequence of the most relevant changes that occurred during embryonic develop- ment. The complete sequence of embryonic development was based on three spawnings (by di¡erent males and females) that occurred in aquaria (temperature: 14^158C). Two additional spawnings, of two other pairs, were also monitored at a slightly higher temperature (16^178C). As the reproduction of this species seems to be inhibited by temperatures above 168C (Monteiro et al., 2001), the ¢sh were kept at 158C and the temperature was raised to 16^178C just after the beginning of pregnancy. RESULTS Nerophis lumbriciformis is a sex-role reversed species. During courtship females are the courting sex. Sexually dimorphic (Figure 1A), the females are more active and more coloured than the males. After egg transfer, parental care is exclusively paternal. Males tend to abandon large concentrations of individuals and are very sensitive to manipulation, especially near its incubating ventral surface (.. personal observation). This incubating surface, £at at the beginning of the incubation period, progressively develops alveoli in order to individually accommodate each egg (Figure 1A). The eggs, with its major axis measuring approximately 1.3 mm (N¼59; range ¼0.7^1.72; average ¼1.298; SD¼0.183), are spherical when spawned but become quite variable in shape due to di¡erent degrees of compression caused by adjacent eggs. The outer membrane is transparent, allowing a clear view of the bright orange yolk sac. This coloration is probably J. Mar. Biol. Ass. U.K. (2003), 83, 4303/1^4 Printed in the United Kingdom Journal of the Marine Biological Association of the United Kingdom (2003) Author: col 2 .. whose personal observa- tion?