Water temperature modulation to prevent the South American rock mussel (Perna perna) from spawning during depuration
Sewage pollution is an increasing problem for Perna perna mussel farmers in Brazil, and there is an urgent need to adopt post-harvest treatments, such as depuration, to reduce the associated microbiological risks. However, depuration of this species has been discouraged by experiences showing that...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Instituto Oceanográfico da Universidade de São Paulo
2024-05-01
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| Series: | Ocean and Coastal Research |
| Subjects: | |
| Online Access: | https://journals.usp.br/ocr/article/view/224949 |
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| Summary: | Sewage pollution is an increasing problem for Perna perna mussel farmers in Brazil, and there is an urgent
need to adopt post-harvest treatments, such as depuration, to reduce the associated microbiological risks.
However, depuration of this species has been discouraged by experiences showing that the animals usually
spawn during this procedure, bringing difficulties for water treatment and making them lighter, weakened, and
undesirable to be traded as a live product. This study aimed at developing a protocol to prevent mussels from
spawning by modulating the water temperature during depuration. For one year (from 2021-07-07 to 2022-
06-29), market-size mussels harvested from the Brazilian southern coast were divided into groups of five and
immersed during 50 hours in sets of experimental units (15 L acrylic aquariums) that emulated depuration
tanks with different water temperatures (ranging from 8°C to 31°C). During this period, the experimental units
were inspected nine times to check for spawning/spawned mussels. Analysis of the overall results showed
that 21 (95.5%) out of the 22 assays resulted in mussels spawning and that this behavior was mostly recorded
(80.3%) within the first 5:30 hours of the assays. The models developed (binary logistic regression) indicate
that conditioning the depuration water to temperatures 5°C lower than those registered at the harvest site holds
the potential to reduce the chances of spawning by more than 50%, and these chances drop to 8.2% when this
difference reaches 10°C. Further studies are needed to show how reducing water temperature during depuration
influences its efficiency in terms of pathogen reduction, aiming to define the best protocol to optimize microbial
removal and minimize spawning.
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| ISSN: | 2675-2824 |