The carragenophyte Kappaphycus alvarezii has been introduced into tropical regions, including Brazil, for aquaculture purposes. Our study estimated the biomass loss of farmed cuttings, the establishment of cuttings outside the rafts, the occurrence of spores, and evaluated the invasive potential of K. alvarezii at three sites in Rio de Janeiro state. Temperature, salinity, water transparency, wind velocity and direction (hydrodynamic indicator) and solar radiation (irradiance availability indicator) varied spatially. We found no spores in cultivated cuttings and no verified spore recruitment on artificial substrata. Biomass loss of cuttings varied temporally; however, it was restricted to the cultivation management area of one site and was low compared to native algal biomass. The establishment of cuttings was apparently limited by herbivory at Ilha Grande Bay and controlled by water transparency, hydrodynamics and temperature at Sepetiba Bay. The invasive potential of K. alvarezii was considered remote. However, the use of environmental protocols for cultivation activities is necessary to prevent environmental impacts, mainly in tropical regions.

No abstract

No abstract

No abstract

No abstract

No abstract

Seaweeds have many uses in industry and agriculture and many species have potential for integrated multi-trophic aquaculture (IMTA), since they are efficient in removing nutrients from water. The efficiency of Ulva flexuosa, U. fasciata and Gracilaria birdiae in removing nutrients from enriched water and their productive performance in outdoor tanks were quantified. These seaweeds (50 g; n = 5) were grown in tanks containing 50 L of eutrophic seawater, with a salinity of 30, a temperature of 28.5 ± 2.8 °C, an irradiance of 547 ± 458 μmol photons m -2 s -1 and aeration. The nutrients levels were recorded daily and when total nitrogen removal was detected, the biomass was measured. After five days of cultivation, more than 98% of NH3 (H = 1.1; P = 0.56) and NO3 -(H = 2.7; P = 0.25) and 62.1% of PO4 3-(H = 0.0; P = 0.90) had been removed from the tanks. However, the mean daily growth rate (4.5 ± 2.5% day -1 ) and productivity (3.5 ± 1.9 g m -2 day -1 ) of U. fasciata and G. birdiae were higher than U. flexuosa (-13.6 ± 7.7% day -1 ; -6.24 ± 2.8 g m -2 day -1 ; P<0.01), demonstrating that microalga contamination by this species promoted high removal efficiency in the tanks, but a low productive performance. Based on these results, U. fasciata and G. birdiae show a greater potential for use in IMTA to improve water quality and produce biomass.Keywords: Gracilaria birdiae; productivity; daily growth rate; nutrient removal; Ulva fasciata; Ulva flexuosa EFICIÊNCIA BIOFILTRADORA E DESEMPENHO PRODUTIVO DE MACROALGAS COMPOTENCIAL PARA AQUICULTURA MULTI-TRÓFICA INTEGRADA (AMTI) RESUMOAs macroalgas são utilizadas em diversos setores industriais e agrícolas. Além disso, muitas espécies apresentam potencial para aquicultura multitrófica integrada (AMTI), pois são eficientes na remoção de nutrientes da água. A eficiência biofiltradora e desempenho produtivo das macroalgas Ulva flexuosa, U. fasciata e Gracilaria birdiae e foram quantificados em tanques outdoor. As algas (50 g; n = 5) foram cultivadas em tanques de 50 L, com água eutrofizada, salinidade 30 e temperatura média 28,3 °C. Os nutrientes foram monitorados diariamente e a biomassa foi mensurada assim que detectada a extinção do nitrogênio. Após cinco dias de cultivo, mais de 98% de NH3 (H = 1,1; P = 0,56) e de NO3 -(H = 2,7; P = 0,25) e 62,1% de PO4 3-(H = 0,0; P = 0,9) foram removidos dos tanques. Contudo, a taxa de crescimento (% dia -1 ) e a produtividade (g m -2 dia -1 ) de U. fasciata e de G. birdiae (4,5 ± 2,5% dia -1 ; 3,5 ± 1,9 g m -2 dia -1 ) foram superiores às de U. flexuosa (13,6 ± 7,7% dia -1 ; 6,2 ± 2,8; P<0,01), cuja contaminação por microalgas contribuiu para elevada eficiência de retirada nos tanques desta espécie, mas baixo desempenho produtivo. Desta forma, U. fasciata e G. birdiae foram indicadas para AMTI tanto para a manutenção da qualidade da água quanto para aproveitamento de biomassa.

No abstract