Biofiltering efficiency, uptake and assimilation rates of Ulva clathrata (Roth) J. Agardh (Clorophyceae) cultivated in shrimp aquaculture waste water

Abstract

The growth, biofiltering efficiency and uptake rates of Ulva clathrata were studied in a series of outdoor tanks, receiving waste water directly from a shrimp (Litopenaeus vannamei) aquaculture pond, under constant aeration and two different water regimes: (1) continuous flow, with 1 volume exchange a day (VE day -1 ) and (2) static regime, with 1 VE after 4 days. Water temperature, salinity, pH, dissolved inorganic nitrogen (DIN), phosphate (PO 4 ), chlorophyll-a (chl-a), total suspended solids (TSS), macroalgal biomass (fresh weight) and tissue nutrient assimilation were monitored over 12 days. Ulva clathrata was highly efficient in removing the main inorganic nutrients from effluent water, stripping 70-82% of the total ammonium nitrogen (TAN) and 50% PO 4 within 15 h. Reductions in control tanks were much lower (Tukey HSD, P<0.05). After 3 days, the mean uptake rates by the seaweed biomass under continuous flow were 3.09 mg DIN g DW day −1 (383 mg DIN m −2 day −1 ) and 0.13 mg PO 4 g DW day −1 (99 mg PO 4 m −2 day −1 ), being significantly higher than in the static regime (Tukey HSD, P<0.05). The chl-a decreased in seaweed tanks, suggesting that U. clathrata inhibited phytoplankton growth. Correlations between the cumulative values of DIN removed from the water and total nitrogen assimilated into the seaweed biomass (r=0.7 and 0.8, P<0.05), suggest that nutrient removal by U. clathrata dominated over other processes such as phytoplankton and bacterial assimilation, ammonia volatilization and nutrient precipitation.

Growth, protein and carbohydrate contents in Ulva rigida and Gracilaria bursa-pastoris integrated with an offshore fish farm

“…In previous reported trials using Ulva rigida and Gracilaria bursa-pastoris in outdoor growth settings, SGRs were in the 15-30 % day −1 range (Beardall 1989;Msuya and Neori 2010;Nielsen et al 2011) and 5-10 % day −1 range (Friedlander and Ben-Amotz 1991;Levy and Friedlander 1994), respectively. Our results for Ulva growth (12-16 % day −1 ) were also similar to previous studies in which various Ulva species were integrated to land-based multi-trophic aquaculture using tanks (Vandermeulen and Gordin 1990;Neori et al 1991;Neori et al 1998;Copertino et al 2008). Growth rates of G. bursa-pastoris reported in this study were even higher than those reported in tank cultivated Gracilaria (4-8 % day −1 ) (Heerden 1997; Aguiar et al 2003;Nielsen et al 2011).…”

Cultivation of Ulva lactuca with manure for simultaneous bioremediation and biomass production

“…Several authors (Gaevert et al 2007;Hernández et al 2002;Pedersen and Borum 1997) have reported assimilation rates of NH 4 + in the range of 50−90 μmol N g −1 DW h −1 among different Ulva species, and these species have been verified as successful biofilters of wastewaters from aquaculture (Hernández et al 2002;Cahill et al 2010;Copertino et al 2009;Neori et al 2003). Aquaculture effluents are rich in NH 4 + and therefore highly suitable as nutrient source for Ulva species.…”

Differential growth response of Ulva lactuca to ammonium and nitrate assimilation

“…Ammonium and nitrate are the major nitrogen sources of seaweeds in the natural habitat and are used as nourishment for seaweed in integrated multi-trophic aquaculture systems (Copertino et al 2008). Several experiments have been conducted for several seaweed species on the interaction of ammonium and nitrate uptake.…”