Age estimation methods in the marine gastropod Buccinanops globulosus comparing shell marks and opercula growth rings

Age determination in gastropods is an essential tool for understanding the main aspects of population dynamics that allow for the formation of fisheries policies. Small-scale fisheries of the nassariid gastropod Buccinanops globulosus from northern Patagonia are not yet regulated, although it is locally consumed while an incipient commercialization is taking place. The aim of this study was to show the suitability of opercula readings for age estimation in B. globulosus, compared with shell marks, previously validated by the analysis of the stable isotope of oxygen. The individual age estimated by the opercula rings reading method did not match the estimation made by the shell marks reading method. Stable isotope analyses confirmed that shell marks were deposited annually. Proper age estimation for B. globulosus, based on recognizable external shell marks, reached up to 9 years.Fil: Bökenhans, Verena Diana. Universidad Nacional de la Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Bigatti, Gregorio. Universidad Nacional de la Patagonia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Stable Isotopes Reveal Algal Assimilation in the Carnivorous Sea Slug Pleurobranchaea maculata (Quoy & Gaimard, 1832) on Patagonian Coasts

Exotic species that achieve successful invasions often show considerable dietary plasticity in resource choice, sometimes adjusting their diet to new or variable resources. This can increase species' impact in the recipient environment. In this study, we explore the diet of the invasive gray side-gilled sea slug Pleurobranchaea maculata (Quoy & Gaimard, 1832) in two environments with contrasting presence of algae (different depths) on northern Patagonian coasts, by means of stable isotope analysis. Results showed the most probable prey contribution to the diet of shallow individuals of P. maculata to be algae, whereas colonial tunicates were the preferred prey in deep environments. Therefore, we suggest that P. maculata behaves as an omnivorous species in the receiving community, because it consumes and assimilates the algae, which represents a dietary shift compared to their original feeding habits (carnivorous). This species exhibited the ability to adapt to diff erent dietary resources by showing significant differences in niche locations, niche breadth, and exhibiting little to no overlap between different environments, which supports the previous description of P. maculata as a generalist consumer. Pleurobranchaea maculata's dietary plasticity might drive ecological consequences in the invaded community. Thus, it is important to monitor for future changes in the benthic community to develop efficient programs for the management of this invasive voracious species.Fil: Bökenhans, Verena Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Galvan, David Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Universidad Espíritu Santo; EcuadorFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Diet of the invasive sea slug Pleurobranchaea maculata in Patagonian coastal waters

High densities of the invasive sea slug, Pleurobranchaea maculata, have been detected on the Argentinean coast, but studies on the species’ adaptation have been absent until now. Stomach contents of P. maculata in two sampling sites located at Golfo Nuevo, Patagonia Argentina, revealed animals as a major prey, but surprisingly algae ingestion on both sampling sites was abundant. This fact was not reported in previous studies that described opportunistic carnivorous feeding habits of species belonging to the genus Pleurobranchaea. Significant differences in the species prey items were found between sampling sites; however, sedentary polychaetes were the main consumed group at both sites. These results are useful to understand the adaptation of this invasive species in Argentinean waters and to monitor future changes in the benthic communities colonised by P. maculata.Fil: Bökenhans, Verena Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: José E. Fernández Alfaya,. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Gregorio Bigatti. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: AndrésAverbuj. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Age and growth differences in two populations of the edible marine gastropod Buccinanops globulosus

Buccinanops globulosus is an edible marine gastropod that is being captured by artisanal fishermen without management regulations. As basic knowledge on population features is required in case a sustained commercial exploitation of this species is established, we estimated and compared the age and growth of B. globulosus in two populations separated by 16 km, inhabiting similar physical environments but different anthropic influence. Our results, based on stable oxygen isotope analysis and best fitted models by likelihood ratio tests, detected differences in age and growth between both samplings. Maximum shell marks suggest one year difference between populations. Richards was chosen as the best fitting model for both sampling sites and significant differences were observed between them. Human activities could be causing the age reduction among other irreversible effects on the population under anthropic influence. This should be considered when developing sustainable management regulations for this fishery resource, especially those based on shell/age size.Fil: Bökenhans, Verena Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Estimating Age and Growth of the Edible Nassarid Gastropod, Buccinanops cochlidium (Dillwyn, 1817) Using Sclerochronology Records

New marine mollusc fishery resources are constantly being incorporated to the international market. The marine gastropod Buccinanops cochlidium (Dillwyn, 1817) is a potential fisheries resource with excellent nutritional qualities. Recently, the first legislation that regulates marine gastropod fisheries based on size limits and reproductive seasonality was established in Argentina, although some biological parameters that are useful to its implementation are still needed. Fisheries managed with size limits require accurate estimates of age and growth that can be estimated through stable isotope sclerochronology. The age and growth of B. cochlidium at Playa Villarino, in north Patagonian gulf San Jose, Argentina was studied between 2005 and 2006. The 18O profiles of B. cochlidium shells analyzed in this study showed a maximum age of 5 y. Opercular rings and shell growth breaks, which record age in some other gastropods, gave higher counts than the number of years shown in isotope profiles. Thus, morphological proxies are unable to correctly asses age and growth in B. cochlidium. These results are useful to support and complement the first fisheries regulation of marine gastropods recently implemented in Argentina, aimed to conserve this vulnerable and valuable resource.Fil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Herbert, Gregory S.. University Of South Florida; Estados UnidosFil: Bökenhans, Verena Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin