Gregorio Bigatti

Biomonitoring of TBT contamination and imposex incidence along 4700 km of Argentinean shoreline (SW Atlantic: From 38S to 54S)

The imposex incidence and TBT pollution were investigated along 4,700km of Argentinean coast, including city harbors and proximal zones without marine traffic. We analyzed 1805 individuals from 12 gastropod species, including families Volutidae, Muricidae, Nassariidea, Calyptraidae, Marginellidae, and Buccinidae, and found the imposex phenomenon for the first time in six species. In high marine traffic zones, TBT pollution was registered and the percentage of imposex was high, while these occurrences were null in areas without boat traffic. The species that best reflect the degree of imposex were those inhabiting sandy/muddy or mixed bottoms. TBT determination and imposex incidence indicate that pollution was focused only in ports with high marine traffic or in areas where ship hulls are painted. This is the first report of an imposex-sediment approach to evaluate organotin contamination along the coast of a South American country.

Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses.

Imposex in endemic volutid from Northeast Brazil (Mollusca: Gastropoda)

Imposex is characterized by the development of masc uline sexual organs in neogastropod females. Almost 120 mollusk species are known to present imposex when eto organic tin compounds as tributyltin (TBT ) and triphenyltin (TPT). These compounds are used as bio cide agents in antifouling paints to prevent the in crustations on boats. Five gastropod species are known to present imposex in Brazil: Stramonita haemastoma, Stramonit a rustica, Leucozonia nassa, Cymathium parthenopeum and Olivan cillaria vesica. This paper reports the first recor d of imposex observed in the endemic gastropod Voluta eb raea from Pacheco Beach, Northeast Brazil. Animals presenting imposex had regular female reproductive organs (capsule gland, oviduct and sperm-ingesting gland) and an abnormal penis. As imposex occurs in mollusks ex posed to organotin compounds typically found at har bors, marinas, shipyards and areas with high shipping act ivities, probably contamination of Pacheco Beach is a consequence of a shipyard activity located in the n earest areas.

Transplant bioassay induces different imposex responses in two species of the genus Stramonita

Abstract A bioassay to study differential specific responses in imposex development due to marine organotin pollution was done by transplanting specimens of the gastropods Stramonita haemastoma and Stramonita rustica from an imposex-free area to a marina with high marine traffic inside a ship repair yard, a place where local populations of S. haemastoma were known to show high indices of imposex. Three hundred sexually mature, imposex-free specimens of each species were kept in cages for 120 days, and samples of 30 individuals were periodically analysed for imposex development. Shell length, penis length and vas deferens development were recorded and imposex development indices (% imposex, RPLI and VDSI) were calculated. Our results indicated that imposex induction in S. haemastoma is faster and more sensitive than in S. rustica. Imposex incidence in S. haemastoma could be a useful tool for monitoring marine pollution by organotin compounds in harbours along the Brazilian coast.

Phenotypic variability associated with the occurrence of imposex in Odontocymbiola magellanica from Golfo Nuevo, Patagonia

The increasing occurrence of imposex in marine gastropods has been related to their exposure to the tri-substituted organotin compounds tributyltin (TBT) and triphenyltin (TPhT), which have been widely used as antifouling agents, and has been documented for more than 200 gastropod species. Odontocymbiola magellanica, a large benthic neogastropod, showed 85^100% imposex near harbours with high marine tra⁄c in Patagonia. We evaluated if, as predicted by the energy allocation hypothesis, females with imposex (FWI) were on average larger and/or heavier than normal individuals, and if there were diierences in shell morphometry associated with imposex, using both univariate and multivariate approaches. We detected diierences in two morphometric variables, but no overall eiect in shell shape, and *10% of reduction in body weight in FWI. In addition, the multivariate index of size suggested a positive eiect on FWI, in contrast to univariate analyses showing no diierences in shell length. The present results demonstrate that responses to TBT vary among gastropod species and that the energy allocation hypothesis may be useful only under certain conditions.

Butyltins, polyaromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls in sediments and bivalve mollusks in a mid‐latitude environment from the Patagonian coastal zone

Butyltins (BTs), polyaromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) were assessed in a mid-latitude environment of the Patagonian coast, distant from significant pollutant sources. Bioaccumulation processes through bottom sediment resuspension were suggested by BTs level (expressed as ng of tin [Sn] g(-1) dry wt) found in surface sediment (<limit of detection [LOD]-166.5 ng [Sn] g(-1) dry wt) and bivalve mollusks (29.4-206.0 ng [Sn] g(-1) dry wt); whereas imposex incidence was only 15% in the gastropod Pareuthria plumbea collected near a harbor. Low hydrocarbon pollution was found in sediments and bivalves with ∑PAHs(16) ranging from <LOD to 94.9 ng g(-1) dry weight and from <LOD to 54.9 ng g(-1) dry weight, respectively. Values were typical of locations distant from pollutant sources and showed different compositional patterns for both substrates. However, concentrations for some individual PAHs in sediments were found over the threshold effect level. On average, ΣPCB did not exceed the sediment quality guidelines being 0.57 ± 0.88 ng g(-1) dry weight in sediments and 0.41 ± 0.26 ng g(-1) dry weight in bivalves. Average ΣOCPs in sediments were 0.53 ± 0.34 ng g(-1) dry weight and ranged from <LOD to 0.22 ng g(-1) dry weight in bivalves, showing a different pattern and suggesting a different accumulation pathway as was found for PAHs. Although both discrete and atmospheric sources can be considered for PAHs, organochlorines pollution was clearly related to atmospheric global transport, indicating that in the studied area, OCPs and PCBs experience permanent or temporal deposition during their migration to southern zones.

EXPLOITATION OF THE VOLUTE SNAIL ZIDONA DUFRESNEI IN ARGENTINE WATERS, SOUTHWESTERN ATLANTIC OCEAN

Abstract Zidona dufresnei (fine snail) is a common gastropod species in the Southwestern Atlantic Ocean, which has been exported to Asian countries for human consumption since 1988. Landings of Z. dufresnei increased from 1974 to a maximum record of 1,300 mt (whole shelled animal) in 1997, followed by a steady decline through 2002. No resource management effort have been applied to this species since the beginning of its catch history, about 30 y ago. Information provided in this work, together with previous studies on the reproductive biology and population dynamics of Z. dufresnei, will contribute to establish effective precautionary polices to manage this resource. We suggest that Z. dufresnei is in a phase of over-exploitation since 1988 until present, we propose a rational management as size selectivity, with a minimum capture size of 16 cm, closure of the fishery during the reproductive season, from September to December and to rotate the fishing areas. This study provides historical and updated information as an attempt to implement corrective measures towards a better management of the fishery on the Argentine Continental Shelf.

BTs, PAHs, OCPs and PCBs in sediments and bivalve mollusks in a mid‐latitude environment from the Patagonian coastal zone

Butyltins (BTs), polyaromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) were assessed in a mid-latitude environment of the Patagonian coast, distant from significant pollutant sources. Bioaccumulation processes through bottom sediment resuspension were suggested by BTs level (expressed as ng of tin [Sn] g(-1) dry wt) found in surface sediment (<limit of detection [LOD]-166.5 ng [Sn] g(-1) dry wt) and bivalve mollusks (29.4-206.0 ng [Sn] g(-1) dry wt); whereas imposex incidence was only 15% in the gastropod Pareuthria plumbea collected near a harbor. Low hydrocarbon pollution was found in sediments and bivalves with ∑PAHs(16) ranging from <LOD to 94.9 ng g(-1) dry weight and from <LOD to 54.9 ng g(-1) dry weight, respectively. Values were typical of locations distant from pollutant sources and showed different compositional patterns for both substrates. However, concentrations for some individual PAHs in sediments were found over the threshold effect level. On average, ΣPCB did not exceed the sediment quality guidelines being 0.57 ± 0.88 ng g(-1) dry weight in sediments and 0.41 ± 0.26 ng g(-1) dry weight in bivalves. Average ΣOCPs in sediments were 0.53 ± 0.34 ng g(-1) dry weight and ranged from <LOD to 0.22 ng g(-1) dry weight in bivalves, showing a different pattern and suggesting a different accumulation pathway as was found for PAHs. Although both discrete and atmospheric sources can be considered for PAHs, organochlorines pollution was clearly related to atmospheric global transport, indicating that in the studied area, OCPs and PCBs experience permanent or temporal deposition during their migration to southern zones.

Distribution and bioaccumulation of butyltins in the edible gastropod Odontocymbiola magellanica

ABSTRACT Butyltins (BTs) were found in sediments and body tissues of the edible gastropod Odontocymbiola magellanica, in which imposex has been recorded since 2000. BTs in sediments ranged from < MDL to 174.8 ng (Sn) g−1 for TBT, < MDL to 19.2 ng (Sn) g−1 for DBT, and < MDL to 71.8 ng (Sn) g−1 for MBT. In body tissues BTs varied from < MDL to 147.1, < MDL to 77.0 and < MDL to 345.3 ng (Sn) g−1 for TBT, DBT and MBT, respectively. BT concentrations were higher in gonads and digestive glands than in the albumen gland and foot (edible). The highest concentrations of BTs in both sediments and gastropods were found in the harbour area, decreasing with distance to the harbour and areas with less maritime traffic. The Biota-Sediment Accumulation Factor (BSAF) in the different organs was between 0.02–0.42, 0.09–0.35 and 0.08–5.25 for TBT, DBT and MBT, respectively. There were positive correlations between concentrations of BTs in sediments and gastropod body tissues, suggesting that xenobiotic accumulation in O. magellanica occurs mainly through contaminated sediments, rather than water or the food chain. Considering current sediment quality guidelines, our results indicate that acute toxic effects would be expected from TBT exposure, which represents a serious environmental threat for the benthic community. Although the levels of BTs found in the foot of this edible gastropod did not exceed the recommended Tolerable Daily Intake in polluted areas, they should be monitored to ensure the safety of seafood consumers. The alternative antifouling biocides Irgarol and Diuron were not detected in sediments.

REPRODUCTIVE SEASONALITY AND OVIPOSITION INDUCTION IN TROPHON GEVERSIANUS (GASTROPODA: MURICIDAE) FROM GOLFO NUEVO, ARGENTINA

ABSTRACT The reproductive biology of a population of the edible muricid Trophon geversianus inhabiting an intertidal rocky shore in Golfo Nuevo (Chubut, Argentina) was studied regarding the seasonality of oviposition and oviposition induction under laboratory conditions. Sex ratio in the population differed from 1:1 (female biased). The mean shell length was 22 mm for males and 24 mm for females, although the females presented significantly larger maximum sizes. No external sexual dimorphism was evident, whereas the female snails differed internally by the presence of the albumin and capsule gland and by gonad color. Although the population under study inhabits an area with marine traffic and a concentration of 1.9 ng Sn/g, it did not present signs of imposex, in contrast with other sympatric species. T. geversianus presented a marked reproductive seasonality during the study period. Oviposition started in May and concluded in November, when hatching of crawling embryos was registered up to January. This seasonality coincided with changes in water surface temperature, ambient temperature, and photoperiod. Reproductive activities were registered when the environmental stress was minimum. In the aquarium, each female laid an average of 12 egg capsules (range, 6–26) per oviposition event, and needed a total of 25 h (range, 12–57 h) to complete attachment of a single egg capsule. Data presented here could be useful for culture of the species.