RESUMO

Dissolution of anthropogenic CO2 modifies seawater pH, leading to ocean acidification, which might affect calcifying organisms such as bivalve mollusks. Along the Peruvian coast, however, natural conditions of low pH (7.6-8.0) are encountered in the habitat of the Peruvian scallop (Argopecten purpuratus), as a consequence of the nearby coastal upwelling influence. To understand the effects of low pH in a species adapted to these environmental conditions, an experiment was performed to test its consequences on growth, calcification, dissolution, and shell mechanical properties in juvenile Peruvian scallops. During 28 days, scallops (initial mean height = 14 mm) were exposed to two contrasted pH conditions: a control with unmanipulated seawater presenting pH conditions similar to those found in situ (pHT = 7.8) and a treatment, in which CO2 was injected to reduce pH to 7.4. At the end of the experiment, shell height and weight, and growth and calcification rates were reduced about 6%, 20%, 9%, and 10% respectively in the low pH treatment. Mechanical properties, such as microhardness were positively affected in the low pH condition and crushing force did not show differences between pH treatments. Final soft tissue weights were not significantly affected by low pH. This study provides evidence of low pH change shell properties increasing the shell microhardness in Peruvian scallops, which implies protective functions. However, the mechanisms behind this response need to be studied in a global change context.

Assuntos

RESUMO

The present study aimed to evaluate the growth and survival of Nodipecten nodosus larvae grown in a remote settlement system. Two forms of transport were tested, one in a humid/wet, environment and one submerged in seawater, with a control treatment maintained at the Laboratory of Marine Mollusks (LMM). After transport treatments, individuals were populated simultaneously inside floating boxes directly at sea and in containers under controlled conditions in the Laboratory of the Experimental Center for Mariculture (CEMAR). No statistical differences were observed in larval survival relative to the method of transport in the different experiments. However, statistical differences were observed in Evaluation 1 (EVA1) for the survival and growth of larvae transported in submerged seawater and settled in the laboratory. No statistical difference was observed between the control and either wet/humid or submerged treatments in EVA2. The survival values in the control treatment in EVA3 were higher (p<0.05) in relation to the wet and submerged treatments cultivated in the laboratory. It was not possible to observe the presence of pre-seeds in treatments grown at sea. Is possible to transport larvae for 6 hours of travel to be settled in controlled conditions far from their place of origin.

Este estudo teve como objetivo avaliar o crescimento e a sobrevivência de larvas de vieiras Nodipecten nodosus cultivadas em sistema remoto de assentamento. Foram testadas duas formas de transporte, úmido e submerso em água do mar com um tratamento controle mantido no Laboratório de Moluscos Marinhos (LMM). Após serem expostos aos tratamentos de transporte os animais foram povoados dentro de caixas flutuantes, diretamente no mar e em recipientes em condições controladas no Laboratório do Centro Experimental de Maricultura (CEMAR). Não houve diferença estatística na sobrevivência das larvas em relação ao método de transporte nos diferentes experimentos. Observou-se diferenças estatísticas (p<0,05), na avaliação 1 (EVA1), para a sobrevivência e crescimento de larvas transportadas em meio submerso e assentadas no laboratório. Entretanto, não foi observada diferença estatística entre o tratamento controle, úmido e submerso na EVA2. Os valores de sobrevivência no tratamento controle na EVA3 foram superiores (p<0,05) em relação aos tratamentos úmido e submersos cultivados em laboratório. Não foi possível observar presença de pré-sementes nos tratamentos cultivados no mar. Conclui-se que é possível transportar larvas por seis horas de viagem para serem assentadas em condições controladas distante do seu local de origem.

Assuntos

RESUMO

The present study aimed to evaluate the growth and survival of Nodipecten nodosus larvae grown in a remote settlement system. Two forms of transport were tested, one in a humid/wet, environment and one submerged in seawater, with a control treatment maintained at the Laboratory of Marine Mollusks (LMM). After transport treatments, individuals were populated simultaneously inside floating boxes directly at sea and in containers under controlled conditions in the Laboratory of the Experimental Center for Mariculture (CEMAR). No statistical differences were observed in larval survival relative to the method of transport in the different experiments. However, statistical differences were observed in Evaluation 1 (EVA1) for the survival and growth of larvae transported in submerged seawater and settled in the laboratory. No statistical difference was observed between the control and either wet/humid or submerged treatments in EVA2. The survival values in the control treatment in EVA3 were higher (p<0.05) in relation to the wet and submerged treatments cultivated in the laboratory. It was not possible to observe the presence of pre-seeds in treatments grown at sea. Is possible to transport larvae for 6 hours of travel to be settled in controlled conditions far from their place of origin.(AU)

Este estudo teve como objetivo avaliar o crescimento e a sobrevivência de larvas de vieiras Nodipecten nodosus cultivadas em sistema remoto de assentamento. Foram testadas duas formas de transporte, úmido e submerso em água do mar com um tratamento controle mantido no Laboratório de Moluscos Marinhos (LMM). Após serem expostos aos tratamentos de transporte os animais foram povoados dentro de caixas flutuantes, diretamente no mar e em recipientes em condições controladas no Laboratório do Centro Experimental de Maricultura (CEMAR). Não houve diferença estatística na sobrevivência das larvas em relação ao método de transporte nos diferentes experimentos. Observou-se diferenças estatísticas (p<0,05), na avaliação 1 (EVA1), para a sobrevivência e crescimento de larvas transportadas em meio submerso e assentadas no laboratório. Entretanto, não foi observada diferença estatística entre o tratamento controle, úmido e submerso na EVA2. Os valores de sobrevivência no tratamento controle na EVA3 foram superiores (p<0,05) em relação aos tratamentos úmido e submersos cultivados em laboratório. Não foi possível observar presença de pré-sementes nos tratamentos cultivados no mar. Conclui-se que é possível transportar larvas por seis horas de viagem para serem assentadas em condições controladas distante do seu local de origem.(AU)

Assuntos

RESUMO

BACKGROUND: Myogenesis is currently investigated in a number of invertebrate taxa using combined techniques, including fluorescence labeling, confocal microscopy, and 3D imaging, in order to understand anatomical and functional issues and to contribute to evolutionary questions. Although developmental studies on the gross morphology of bivalves have been extensively pursued, organogenesis including muscle development has been scarcely investigated so far. RESULTS: The present study describes in detail myogenesis in the scallop Nodipecten nodosus (Linnaeus, 1758) during larval and postmetamorphic stages by means of light, electron, and confocal microscopy. The veliger muscle system consists of an anterior adductor muscle, as well as four branched pairs of striated velum retractors and two pairs of striated ventral larval retractors. The pediveliger stage exhibits a considerably elaborated musculature comprising the velum retractors, the future adult foot retractor, mantle (pallial) muscles, and the anterior and posterior adductors, both composed of smooth and striated portions. During metamorphosis, all larval retractors together with the anterior adductor degenerate, resulting in the adult monomyarian condition, whereby the posterior adductor retains both myofiber types. Three muscle groups, i.e., the posterior adductor, foot retractor, and pallial muscles, have their origin prior to metamorphosis and are subsequently remodeled. CONCLUSIONS: Our data suggest a dimyarian condition (i.e., the presence of an anterior and a posterior adductor in the adult) as the basal condition for pectinids. Comparative analysis of myogenesis across Bivalvia strongly argues for ontogenetic and evolutionary independence of larval retractors from the adult musculature, as well as a complex set of larval retractor muscles in the last common bivalve ancestor.