Embryonic development of the southern surf crab <em>Ovalipes trimaculatus</em> (Decapoda: Brachyura: Portunoidea)

Abstract

Summary:The embryogenesis of Ovalipes trimaculatus, a member of the highly valued portunid swimming crabs, was studied under nearly constant temperature (13±1°C), salinity (33) and photoperiod (14 h light:10 h dark) conditions. A five-stage scale of embryonic development was defined for the species. Time required to complete development averaged 35.7±2.11 days, showing no significant differences between embryos located in inner, middle and outer portions of the egg mass. The egg chorion was rounded and showed the highest growth in diameter between stages I (morula-blastula-gastrula) and II (primordium of larval structure) and between stages III (appendage formation) and IV (eye formation). Results reported here provide a baseline for optimizing hatchery operations and useful information for management purposes.Keywords: crustacean; crabs, aquaculture; Ovalipes trimaculatus; embryology.Desarrollo embrionario del cangrejo nadador Ovalipes trimaculatus (Decapoda: Brachyura: Portunoidea) Resumen: Se estudió la embriogénesis del cangrejo nadador Ovalipes trimaculatus, miembro de la familia de portúnidos altamente valorados, bajo condiciones constantes de temperatura (13±1°C), salinidad (33) y fotoperíodo (luz 14h:10h oscuridad). Se definió una escala de cinco etapas de desarrollo embrionario para la especie. El tiempo necesario para completar el desarrollo es de 35.7±2.11 días, sin mostrar diferencias significativas entre embriones ubicados en porciones interior, media y exterior de la masa de huevos. Los huevos son esféricos y presentan mayor crecimiento en diámetro entre las etapas I (mórula -blástula -gástrula) y II (primordio de estructuras larvarias) y entre las etapas III (formación de apéndices) y IV (formación de los ojos). Los resultados aquí presentados proporcionan la base para la optimización del cultivo y brindan información útil para el manejo de la especie.Palabras clave: crustáceos; cangrejos; acuicultura; Ovalipes trimaculatus; embriología.Citation/Como citar este artículo: Martelli A., Tapella F., González-Pisani X., Dellatorre F., Barón P.J. 2016. Embryonic development of the southern surf crab Ovalipes trimaculatus (Decapoda: Brachyura: Portunoidea). Sci. Mar. 80(4): 499-509.

Effects of temperature and salinity on the development and survival of the embryos and zoeae I from the southern surf crab Ovalipes trimaculatus (Brachyura: Portunidae)

“…Within 6-24 °C and 30-33‰ (Set I of experiments), the chronology of embryonic development remained the same in all treatments, following the pattern described by Martelli et al (2016) with salinity (Table II, Figure 1). At the lowest experimental temperature (6 ⁰C) embryogenesis lasted up to 63 days, and as temperature increased to the highest tested value (24 ⁰C) its length decreased exponentially down to 19 days (Figure 2).…”

“…At the time of arrival to the aquarium, specimens were acclimated in lidded plastic tanks (85 × 85 × 60 cm) containing filtered seawater at 13° ± 1°C and 33 ± 1‰, simulating the average SST and salinity conditions through the reproductive season in Nuevo Gulf (Rivas & Ripa 1989, Dellatorre et al 2012, and were provided with continuous aeration, a layer of macroalgae to use as refuge, and a 12:12 h photoperiod simulating the natural light cycle at the experimental period. Just after arrival to the aquarium, embryo samples were taken from the ovigerous mass of each female and staged under dissecting microscope following the scale of embryonic development developed by Martelli et al (2016). Ovigerous females carrying embryos at intermediate or advanced stages of development were returned to the wild.…”

“…Ovigerous females carrying embryos at the fi rst stage of development (Martelli et al 2016) were placed together in groups of 2 or 3 in 100-liter capacity lidded aquaria (85 × 85 × 60 cm; 2 aquaria per each treatment), provided with sand bottom, continuous aeration and refuges, and were feed ad libitum with fresh Argentinean hake (Merluccius hubbsi) meat. About 20% of seawater volume in the tanks was renewed daily, preserving the environmental variables from each treatment.…”

“…Daily, 50-eggs were taken with thin surgical pincers from the inner ovigerous mass of every female in each experimental treatment, placed in seawater on excavated slides and examined in vivo under an Olympus stereomicroscope CH30 (Tokyo, Japan) with total magnification of 100x. Based on changes in morphological and physiological characters described by Martelli et al (2016), the stage of development and embryonic survival (S) were observed in the samples every day. Finally, the length of embryogenesis (L), counted in days from the date of collection of each ovigerous female carrying eggs at the fi rst stage of development to the date of hatching was registered.…”

“…The embryonic development of O. trimaculatus has been studied at a single combination of temperature and salinity (Martelli et al 2016); still, is necessary to conduct experimental work to determine the optimal combined thermo-haline conditions leading to maximum survival and highest development rate. On the other hand, even when information is available on the survival of O. trimaculatus zoeae I from the Indian Ocean (Algoa Bay, South Africa) exposed for a brief period (≤ 24 h) to several thermo-haline conditions (Du Preez & McLachlan 1984), neither this information fulfills the requirements for aquaculture practice design and larval recruitment modelling, nor its extrapolation to individuals from populations on the coasts of South America can be considered reliable.…”