Release of nutrient from fish food and effects on Microcystis aeruginosa growth

Abstract

This study aimed to explore the relationship between Microcystis aeruginosa growth and nutrients released from fish food, which mainly simulates the effect of uneaten food on algae growth and water quality variables during aquaculture activities. Fish food (0, 0.1, 0.2, 0.5 and 1 g dosages tested) of different grain sizes (original; 0.147 ≤ d ≤ 0.85 mm; d ≤ 0.147 mm) was added each into M‐II culturing medium (nitrogen and phosphorus absent). During the experimental running period, the concentrations of total phosphorus (TP), orthophosphate phosphorus (PO43−‐P), total nitrogen and ammonia‐nitrogen (NH4+‐N) increased significantly with increasing fish food dosages regardless of their grain sizes. Furthermore, grain size had a negligible effect on nutrient release from fish food with the same dosage. Based on the above experiment, M. aeruginosa was introduced into the culturing media at different dosages (nitrogen and phosphorus absent) with 0, 0.05, 0.1, 0.2 and 0.5 g fish food to assess algae growth characteristics. Algae cell density significantly increased with the dosage ranging from 0 to 0.2 g. NH4+‐N and PO43−‐P were the main fractions of available nutrients used by M. aeruginosa in the fish food. In comparison to the growth dynamics of algae in M‐II culturing medium, the lag phase for M. aeruginosa in the presence of fish food extended significantly when calculating the time from the addition of fish food and insignificantly when the time for nutrient release from fish food was excluded.

Fish Feed Quality Is a Key Factor in Impacting Aquaculture Water Environment: Evidence from Incubator Experiments

“…In addition, aquaculture activities not only stimulate algal growth but also affect phytoplankton communities 40,41 along with deteriorating water quality and adversely influencing human health aquaculture activities 42 . Wu et al 's results showed that the release of N and P from fish feed stimulated algae growth 43 . Algae densities increased with increasing fish feed dosages in moderate nutrients concentrations from fish feed 43 .…”

“…Wu et al 's results showed that the release of N and P from fish feed stimulated algae growth 43 . Algae densities increased with increasing fish feed dosages in moderate nutrients concentrations from fish feed 43 . In Huang et al 's study, enclosures with fish feed have higher algae biomass than those without fish feed, and blue-green algae dominated phytoplankton communities in enclosures with fish feed 28 .…”

“…Affected by organic enrichment and sediment resuspension by shrimp, a shift in species dominance from Diatoms and Dinoflagellates to green algae was observed in shrimp aquaculture ponds in Hugues et al 's study 44 . In sum, although fish feed qualities were also not considered in Rahman et al 37 , Wu et al 43 and Huang et al 's 28 studies, the effect of different fish feed quality on algae growth is worthy to be studied.…”

Changes in water quality and the phytoplankton community associated with tilapia cage farming in tropical lakes

“…Algae proliferation, a reduction in dissolved oxygen, reduced water transparency and their consequences for the phytoplankton and zooplankton communities are well-known consequences of aquaculture. Commonly, proliferation of undesirable algae (including Chlorophyceae) is caused by the amplification of nutrients associated with fish farming (Wu et al 2012). Here, we explore how tilapia cage farming influences phytoplankton community structure in eastern Brazil in the state of Espírito Santo.…”

Primary Factors Affecting Growth of Microalgae Optimal Light Exposure Duration and Frequency

“…When TP equals to 0.02mg/L, microalgae can grow well, but the concentration of phosphorus has no promotion to growth rate of algae when TP ≥ 0.2mg/L (Xu et al, 2006). Microalgae also select different formation of phosphorus, using different phosphors source to study, the result of research showed that dipotassium hydrogen phosphate is the biggest consumption for microalgae, which means this form of phosphorus is useful for microalgae growing (Wu et al, 2012).…”