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Disseminated neoplasia is reported for the first time in Ameghinomya antiqua (Veneridae) from Chile on the southeastern Pacific coast. A total of 710 clams were collected in winter 2019 and summer 2021 from five sites in three regions: Coquimbo. Biobio. and Los Lagos: all clams were processed by histology. The disease was only detected in clams from the Biobio region. It was characterized by the presence of numerous neoplastic cells with enlarged nuclei and high nuclear to cytoplasmic volume ratios and the almost absence of normal hemocytes. The prevalence did not vary between seasons (7% in winter and 9% in summer). KEY WORDS: neoplasia, venerid clam. Chile, Southeastern Pacific Ocean, INTRODUCTION Cancers normally arise from mutations in an organism's own cells, and they either regress or continue to grow until they kill the host organism. Cancer cells can grow and [...]

Oysters are farmed worldwide and one of the main problems is infestation by polydorin polychaetes. The native Crassostrea gasar and the exotic Pacific Crassostrea gigas oysters support aquaculture production along the subtropical southern Brazilian coast. Worm infestation rates in the two oyster species were evaluated, hypothesizing that infestation is related to stocking densities and hydrodynamic intensity. The main oyster production areas in Brazil were sampled: Parana state, Medeiros (25[degrees] 22' S, 48[degrees] 27' W), Ponta Oeste da Ilha do Mel (25[degrees] 29' S, 48[degrees] 22' W), and Cabaraquara (25[degrees] 49' S, 48[degrees] 34' W) and the Santa Catarina state, Riberao da Ilha (27[degrees] 43' S, 48[degrees] 33' W). Generalized linear models were performed to analyze the effects of sites characterized by different stocking density, hydrodynamic intensity and mean sea surface temperature (SST), the condition index, and the oyster species (native or exotic). Polydorin infestation was higher (mean of 6.02 polydorins/oyster) under higher oyster stocking densities and intermediate hydrodynamic intensity sites (Riberao da Ilha, in the Santa Catarina state). In Parana State, the two sites with similar stocking densities, Ponto Oeste (7,638 oysters/[m.sup.2]) and Cabaraquara (7,550 oyster/[m.sup.2]) presented a higher polydorin infestation in the site with low hydrodynamic intensity and higher mean SST (5.34 vs. 2.64 polydorins/oyster, respectively). The condition index was not impacted by the polydorin infestation. Native C. gasar showed a higher polydorin infestation than the exotic C. gigas (6.02 vs. 1.36, respectively), indicating a higher vulnerability to worm infestation. These results may lead to a better understanding of the infestation patterns of locally grown oysters and to the implementation of better farming management. KEY WORDS: spionids, shell-boring, aquaculture, oysters, Brazil, INTRODUCTION Oysters are farmed globally and their commercial production has increased rapidly in recent decades (Wijsman et al. 2019, FAO 2020). Many direct and indirect factors can affect the functioning [...]

ABSTRACT The yellow clam Amarilladesma mactroides (Deshayes, 1854) is considered a vulnerable species since the mid-1990s. Populations have experienced mass mortalities throughout their entire range of distribution (23-41°S) along exposed [...]

ABSTRACT Disseminated neoplasia in cultured Mytilus chilensis (Mytilidae) from the Beagle Channel (Tierra del Fuego Province) in southern Argentina has been detected for the first time. The disease is characterized [...]

ABSTRACT This work describes the parasites and their respective pathologies in the stout razor clam, Tagelus plebeius (Lightfoot, 1786) (Psammobiidae) from Argentinean coasts. It represents the first report about a [...]

ABSTRACT Results of the histopathological study of mantle tissues of the commercial geoduck Panopea abbreviata hosting the nemertean Malacobdella arrokeana revealed that the normal histology of mantle tissues of the [...]