Perspectives of marine biodiversity studies in Argentina

This paper provides an overview of the research being carried out at the moment by a group of Argentinean scientists working on the subjects of marine biodiversity and oceanography. When the idea of the Census of Marine Life (CoML)was proposed following the Symposium held during the IAPSO-IABO conference in Mar del Plata in October 2001, there was a wide response from the marine scientific community. Information about current research projects, as well as plans for future work in the context of the CoML, were then obtained from about 70 scientists (Appendix I) belonging to 12 institutions located along the Argentinean coast (Appendix II, Figure 1). This has been used to illustrate what is currently being pursued in marine biodiversity in Argentina and which subjects are considered as priority for future research in the area. This paper is, thus, not an historical update of the knowledge of marine biodiversity, but it attempts to give an idea of the current situation and what is planned for the future. The development of an extensive database of what is known on marine biodiversity in the region is considered to be a necessity, but it constitutes a complete project on its own; as such it is included in the proposals for future work (see Future Work in this paper). It is emphasised that this synthesis is not exhaustive in the content of the topics being studied or in the number of researchers working in marine biodiversity in the country. It is, though, considered to be a representative sample of the knowledge in marine science in Argentina today. This is a starting point for the CoML project in South America and it is hoped that, as it develops, it will be improved by the active participation, advice and experience of many other scientists in the region

Zygochlamys patagonica beds on the Argentinian shelf. Part II: Population dynamics of Z. patagonica

La dinámica de poblaciones del bivalvo Zygochlamys patagonica se investigo en el banco de moluscos ·' "Reclutas" en la plataforma continental argentina entre 1995 y 1998. Se observó un reclutamiento exitoso en 1994 y menos intenso en 1995 mientras que en 1996 y en 1998 no se detecto reclutamiento. El crecimiento individual se describió mejor con el modelo de von Bertalanffy H1 = 74.70 mm x (1- e-0.4l9 Cr - 0·314)) basado en observaciones de anillos de crecimiento. La formación anual de anillos de crecimiento naturales en la valva se validó con el análisis de isótopos estables (3180 y 313C). La relación producción anual-biomasa (P/B) decreció de 0.693 f 1 en 1995 a 0.638 y-1 en 1998 mientras que la producción aumentó de 21.1 g SFWM-m- -y-1 a 77.2 g SFWM-m-2-y-1. El musculo, el tejido blando y las gónadas contribuyeron con 37 %, 56 % y 7 % a la producción total, respectivamente. En promedio, la relación anual P/B fue 0.679 y-1 y la tasa de morcalidad Z, 1.039 y-1.Population dynamics of the scallop Zygochlamys patagonica were investigated on the scallop bed "Reclutas" on the Argentinian shelf between 1995 and 1998. Successful recruitment was observed in 1994 and to a lesser extent in 1995, whereas no recruitment occurred between 1996 and 1998. Individual .flrowth was described best by the von Bertalanffy growth model, H! = 74.70 mm x (1 - e-0. 9(r - 0.3t4>), based on natural growth rmg readmgs. Annual formation of natural growth rings in the shell was validated by stable isotope (6180 and 613C) analysis. The annual production-biomass ratio (P/B) decreased from 0.693 y-1 in 1995 to 0.638 r1 in 1998, whereas production increased from 21.1 g SFWM-m-2-y-1 to 77.2 gSFWM-m-2-y-. Muscle, soft tissue and gonad contributed 37 %, 56 % and 7 % to total production, respectively. On average, the annual P/B ratio was 0.679 y-1 and the mortality rate, Z was estimated to be 1.039 y-1.Fil: Lasta, Mario. Instituto Nacional de Investigaciones y Desarrollo Pesquero; ArgentinaFil: Valero, Juan. Washington State University; Estados UnidosFil: Brey, Thomas. Polar and Marine Research; AlemaniaFil: Bremec, Claudia Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Preliminary survey of the benthic communities of the Patagonian shrimp fishing grounds in San Jorge Gulf (Argentina)

Benthic sampling was carried out in the Patagonian shrimp (Pleoticus muelleri Bate, 1888) fishing grounds in San Jorge Gulf, Argentina, in order to determine composition, spatial distribution and relative abundance of the species in the benthic communities. Biological samples were taken with an epibenthic sledge in 66 sampling stations, and 57 sediment samples for granulometric analysis with a Picard dredge. A total of 135 taxa from the benthic communities were identified. Cluster Analyses (Q and R modes) were applied using the Fager (Fager and McGowan, 1963) and Czekanowski (Legendre and Legendre, 1979) indexes. Faunistic and sedimentological studies clearly define two areas with particular benthic communities. The dominant species in area 1, characterized by muddy and muddy-sandy sediments, are Nuculana sulculata (Couthouy, 1852), Nucula puelcha D’Orbigny, 1842 and Pseudechinus magellanicus (Philippi, 1857). The dominant species, mainly colonial elements, in area 2 which is characterized by gravel-sandy sediments are Sertulariidae, Bowerbankia sp. and Aetea. The relationships between Patagonian shrimp juveniles and a particular benthic community are discussed, considering the presence of the species as an integrant of the epifaunal benthos