Evaluation of Barley Straw and a Commercial Probiotic for Controlling Prymnesium parvum in Fish Production Ponds

Some microalgae are able to kill or inhibit nutrient-competing microalgae, a process called allelopathy. Inhibiting or killing competitors enable these species to monopolize limiting resources, such as nitrogen and phosphorus. Prymnesium parvum is known to produce such allelopathic compounds, substances that seem identical to the ichthyotoxins identified from this species. Biotic and abiotic environmental factors influence not only growth rates but also toxin ⁄ allelopathic compounds production by P. parvum cells. Toxin production, as well as allelopathy, including grazer deterrence, increases dramatically in light, temperature, or nutrient stressed P. parvum cells. Correspondingly, toxicity and allelopathy may decrease, or cease completely, if cells are grown with high amounts of N and P in balanced proportions. However, even under nutrient (N and P) sufficient conditions, P. parvum is able to produce toxins ⁄ allelopathic compounds, with negative effects on other phytoplankton species or grazers, if cells densities of P. parvum are high relative to other species. This negative effect might shift the plankton community to more toxin resistant species. Filtrates from nutrient-deficient P. parvum cultures have almost the same strong negative effect on grazers and other phytoplankton species as when Prymnesium cells are grown together with the target organisms. Eutrophication, the increased input of N and P to aquatic ecosystems, besides increasing nutrient concentrations, is usually provoking unbalanced N:P condition for the optimal growth of phytoplankton, deviating from the Redfield ratio, i.e., the phytoplankton cellular nitrogen to phosphorus ratio, N:P = 16:1 (by atoms) or 7.2:1 (by weight). Eutrophication thus both enhances P. parvum growth and increases production of toxins and allelopathic compounds. Supplying N-deficient or P-deficient P. parvum cells with the deficient nutrient reduces toxicity to less than half within 24 h after additions. As P. parvum is mixotrophic, uptake of dissolved or particulate organic N (DON or PON) can also reduce toxicity and allelopathy in the same manner as addition of inorganic N to Nstarved cells. In conclusion, P. parvum, by increasing its toxicity and allelopathic ability under poor environmental conditions, outcompetes the co-occurring phytoplankton species.

Section: Inhibiting Toxicity and Allelopathy In Prymnesium Parvummentioning

confidence: 99%

Factors Influencing Allelopathy and Toxicity in Prymnesium parvum¹

Granéli¹,

Salomon²

2010

“…Barkoh et al . () found that probiotics did not reduce golden alga toxicity or abundance in hatchery ponds, but suggested that the application rate used in their study was probably too low to reduce nutrients to their desired level. Although probiotics have not yet been evaluated at a larger scale (i.e., reservoirs), the association found in the present study between golden alga and high organic nitrogen loads suggests further research is warranted.…”

Section: Discussionmentioning

confidence: 89%

Spatiotemporal Associations of Reservoir Nutrient Characteristics and the Invasive, Harmful Alga Prymnesium parvum in West Texas

VanLandeghem

Farooqi

Southard

et al. 2014

Golden alga (Prymnesium parvum) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga. (KEY TERMS: algae; aquatic ecology; environmental impacts; nutrients.) VanLandeghem, Matthew M., Mukhtar Farooqi, Greg M. Southard, and Reynaldo Patiño, 2015. Spatiotemporal Associations of Reservoir Nutrient Characteristics and the Invasive, Harmful Alga Prymnesium parvum in West Texas.

“…In this study, copper sulfate was not as effective for P. parvum as the chelated‐copper formulation. Neither barley straw nor Liquid Live Micro‐Organisms™ were effective for control of P. parvum in pond situations in Texas (Barkoh et al. , 2008).…”

Section: Resultsmentioning

confidence: 99%

Comparison of Three Algaecides for Controlling the Density ofPrymnesium parvum¹

Rodgers

Johnson

Bishop

2010

Prymnesium parvum has become more prevalent in water resources of the southern United States. As the potential impacts of P. parvum are relatively well known, especially its capability to severely affect fish, managers have sought efficacious, environmentally sound, and socially acceptable strategies for mitigating this noxious species. Laboratory testing was used to identify an effective algaecide for control of P. parvum from Texas, Arizona, Florida, North Carolina, and South Carolina. Cutrine Ò -Plus at 0.2 mg Cu ⁄ l significantly decreased the density of P. parvum in samples from all of these locations. Both copper sulfate and Phycomycin Ò were less effective for controlling the population growth of P. parvum. The predicted response from the laboratory study was confirmed in the field at the Arizona site. Strategic use of Cutrine Ò -Plus in larger water resources could provide toxin-free refugia to allow some fish to survive and repopulate the water resource when the golden alga infestation abates.