Aquaculture diversification through bio-mitigation: innovative integrated multi-trophic aquaculture IMTA models with low trophic species

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Comparison of the efficiency of different eradication treatments to minimize the impacts caused by the invasive tunicate Styela plicata in mussel aquaculture

Publication . Santos, Pedro M.; Venâncio, Eliana; Dionísio, Maria Ana; Heumüller, Joshua; Chainho, Paula; Pombo, Ana

In 2017, aquaculture producers of the Albufeira lagoon, Portugal, reported an invasion of tunicates that was disrupting mussel production, particularly the tunicate Styela plicata (Lesueur, 1823). A totally effective eradication method still does not exist, particularly for S. plicata, and the effects of the eradication treatments on bivalves’ performance are also poorly understood. Our study examined the effectiveness of eradication treatments using three laboratory trials and five treatments (air exposure, freshwater immersion, sodium hypochlorite, hypersaline solution and acetic acid) for S. plicata, as well as their effects on survival and growth of blue mussel Mytilus edulis Linnaeus, 1758. While air exposure and freshwater immersion caused a 27% mortality rate in S. plicata, the acetic acid treatment was the most effective in eliminating this species (>90% mortality). However, a 33–40% mortality rate was registered in mussels. Both species were not affected by the hypersaline treatment in the last trial, but the sodium hypochlorite treatment led to a 57% mortality rate in mussels. Differences in mussels’ growth rates were not detected. These trials represent a step forward in responding to the needs of aquaculture producers. However, further studies are needed to investigate the susceptibility of tunicates to treatments according to sexual maturation, as well as to ensure minimum mussel mortality in the most effective treatments, and to better understand the effects on mussel physiological performance in the long-term.

2023Journal article

Open access

Effect of salinity on somatic growth and gonadal enhancement of the sea urchin Paracentrotus lividus (Lamarck, 1816)

Publication . Santos, Pedro M.; Silva, João A.; Costa, José Lino; Pombo, Ana

Salinity plays a major role in several physiological processes in sea urchins, including reproduction and growth, ultimately affecting survival. Optimal salinity ranges vary considerably between species, as a consequence of ecological adaptations. However, related research in the context of aquaculture is quite scarce, particularly for the stenohaline sea urchin Paracentrotus lividus (Lamarck, 1816), a target species for aquaculture diversification in Europe. It is thus important to better understand the response of this species to hyposalinity conditions over an extended rearing period. Four salinity treatments (20, 25, 30 and 35 psu) were evaluated, over 120 days, in terms of survival, feed intake, growth, gametogenic development and gonadal colour in P. lividus. While a 100% survival was obtained in all treatments, salinity significantly affected all other parameters. Sea urchins reared at 20 psu presented significantly lower linear and specific growth rates, feed intake, gonadosomatic index, as well as a higher feed conversion ratio. While sea urchins reared at 30 and 35 psu were mostly mature, hyposalinity led to a slower gametogenic progression in the lower salinities, particularly at 20 psu. Gonad colouration was only affected in males, as individuals reared at 20 psu presented less brighter, but more reddish and yellowish gonads. The results clearly demonstrate that despite the absence of mortality, rearing salinities of 20 and 25 psu promote a negative effect on somatic and gonadal yield of P. lividus.

2022Journal article

Restricted access