Growth, nitrate uptake kinetics, and biofiltration potential of eucheumatoids with different thallus morphologies

Abstract

The declining production of commercially important eucheumatoids related to serious problems, like increasing susceptibility to ice–ice disease and epiphytism, may be ameliorated by nutrition. This ushered an increasing interest in incorporating seaweeds into an integrated multi‐trophic aquaculture (IMTA) setup to take up excess inorganic nutrients produced by fish farms for their nourishment. In this regard, it is important to understand the nutrient uptake capacity of candidate seaweeds for incorporation into an IMTA system. Here, we examined the growth, nitrate (NO3‐) uptake kinetics, and biofiltration potential of Eucheuma denticulatum and three strains of Kappaphycus alvarezii (G‐O2, TR‐C16, and SW‐13) with distinct thallus morphologies. The NO3‐ uptake rates of the samples were determined under a range of NO3‐ concentrations (1–48 µM) and uptake rates were fitted to the Michaelis–Menten saturation equation. Among the examined eucheumatoids, only SW‐13 had a linear response to NO3‐ concentration while other strains had uptake rates that followed the Michaelis–Menten saturation equation. Eucheuma denticulatum had the lowest Km (9.78 ± 1.48 µM) while G‐O2 had the highest Vmax (307 ± 79.3 µmol · g−1 · min−1). The efficiency in NO3‐ uptake (highest Vmax/Km and α) was translated into the highest growth rate (3.41 ± 0.58% · d−1) measured in E. denticulatum. Our study provided evidence that eucheumatoids could potentially take up large amount of NO3‐ and fix CO2 when cultivated proximate to a fish farm as one component of an IMTA system. During a 45 ‐d cultivation period of eucheumatoids, as much as 370 g NO3‐ can be sequestered by every 1 kg initial biomass of E. denticulatum growing at 3% · d−1. Furthermore, based on our unpublished photosynthetic measurements, the congeneric K. striatus can fix 27.5 g C · kg−1 DW during a 12 h daylight period.

Impacts of aquaculture nutrient sources: ammonium uptake of commercially important eucheumatoids depends on phosphate levels 1

“…In general, a high nutrient level tends to improve growth and nutrient uptake in seaweeds. For instance, K. alvarezii had higher growth and nutrient uptake at high levels of nutrient (Luhan et al 2015;Narvarte et al 2022). Moreover, Fucus vesiculosus samples that were enriched with N displayed the highest P uptake e ciency at biologically relevant P levels (Perini and Bracken 2014).…”

The Most Efficient Seaweed Species as a Bioremediator of Intensive Pond Waste

“…The absorption rate of seaweed increases linearly with nutrient availability, even though it exceeds the need for its growth (Harrison & Hurd, 2001;Wang et al, 2023). Thus, the availability of nutrients in the area around the seaweed is one of the most important factors affecting its uptake (Narvarte et al, 2022). That is, the continuous movement of water through aeration is thought to spread nutrients evenly across the distribution of seaweed in the tank.…”

“…The absorption rate of seaweed nutrients depends on several physical factors (temperature, salinity, light, and water movement), chemical factors (nutrient concentrations and limiting nutrient types, such as NO 3 -N), and biological factors (nutritional history, life history, and morphology) (Harrison & Hurd, 2001;Narvarte et al, 2022). In this study, the temperature and salinity were relatively the same in each tank (Table 2), also the light source was the same (all tanks were indoors with LED lights), and each tank was supplied with the same aeration system.…”

Impacts of aquaculture nutrient sources: ammonium uptake of commercially important eucheumatoids depends on phosphate levels

“…Eucheumatoids are a group of macroalgae that are considered good candidate species in an IMTA setup due to their bio ltration potentials and established market (Rodrigueza and Montaño 2007; Melendres 2021; Narvarte et al 2022). These macroalgae are farmed globally due to their phycocolloid (carrageenan) content, which is used in a wide array of economic and industrial applications (Bixler and Porse 2011).…”