Factors governing the Toxicity of Cultures containing the Phytoflagellate Prymnesium parvum Carter

Abstract

SUMMARY: Methods for the laboratory maintenance and purification of cultures of Prymnesium parvum are detailed. The upper limit of temperature for the growth of the organism is 30". Light exerts an augmenting effect on the production of the toxin by Pr. paruum. Rapid and economical procedures for the bioassay of the toxin are based on the use of Gambusia minnows or tadpoles. Cell-free centrifugates of the cultures contain heat-labile toxic material which is non-diffusible through cellophan, sensitive to oxidizing agents, and reversibly inactivated by mild acidity. The toxin is rapidly inactivated by ubiquitous bacterial species (Bacillus subtilis and Proteus vulgaris). Charcoals, clays and calcium sulphate are efficient adsorbents of the toxic material. The concentration levels of toxin in cultures of Prymnesium parvum appear to reflect a dynamic equilibrium between toxin destruction and production ; a similar equilibrium may prevail in nature., 4 phytoflagellate toxin was first implicated in an occurrence of mass mortality among fish in Holland by Liebert & Deerns (1920). Subsequent study of a similar occurrence in Denmark by Otterstroem & Steeman-Nielsen (1939) identified the responsible organism as Prymnesium parvum Carter, and confirmed that the toxic effect was caused by an extracellular thermolabile toxin. Reich & Aschner (1947) described the widespread occurrence of this organism in Israel and proposed measures for its control in fishponds.The present communication describes methods for the maintenance and purification of laboratory cultures of Prymnesium spp. and procedures for the bioassay of the toxin. An analysis of the effects of certain environmental factors on the production and persistence of the toxin in pond water has been attempted. The experiments show the extracellular occurrence of the prymnesium toxin and suggest that it may be a protein. EXPERIMENTALBioassay of the toxi% of Prymnesium parvum Estimations of toxin content of culture fluids and of pond water were made by using Gambusia minnows or tadpoles of Rana or Bufo as the test organism. These species were readily available and could be handled in relatively small volumes of fluid. The tests are carried out as follows. For tadpole tests, five animals are immersed in 5 ml. volumes in 15 mm. diam. test-tubes. Cell-free centrifugates of the toxic samples are used for the assay. The dilution medium was sodium chloride solution (0.16 yo), 9 volumes + Sorensen's phosphate G M VIII 3 22

Effects of Harmful Algal Blooms on Fish: Insights from Prymnesium parvum

“…This could explain why different strains of P. parvum express different toxicities [9] and could be the reason for the discrepancy between the results reported in this study (strain: UTEX-2797) and those previously reported by Bergmann et al [41] for an unknown strain. Furthermore, observed P. parvum toxicity is sensitive to handling [44] and the composition of the aquatic environment [43]. Lastly, the material used in the experimental setup affects observed toxicity as well, as prymnesins readily bind to polymeric surfaces (log d = 3.4-5.2) [60].…”

“…At the time of the experiment, the proposed toxins (the prymnesins [38]), were unquantifiable [39,40]. Whether prymnesins are the sole toxins in a P. parvum bloom is debatable, so controlling for prymnesin content might confound the effects of other unknown toxins [7,8,[40][41][42][43]. Significant variations in toxicity have been reported when exposing fish externally to P. parvum culture [8,40].…”

“…Significant variations in toxicity have been reported when exposing fish externally to P. parvum culture [8,40]. The P. parvum toxicity has been reported to vary with pH [7,43], temperature, adsorbents, oxidizing agents [43], and mechanical disturbance [44]. All of the above contribute to our choice to normalize the exposure to culture cell count and regulate environmental factors such as temperature and oxygen levels.…”

Haemolytic activity and allelopathy of the haptophyte Prymnesium parvum in nutrient-limited and balanced growth conditions

“…Studying the characteristics of P. parvum has been motivated by the large economic losses it has caused, especially in fish farms (Edvardsen & Paasche 1998). P. parvum damages fish by destroying their gills (Yariv & Hestrin 1961, Shilo 1971 through toxins the cells excrete into the water (Shilo & Aschner 1953, Shilo & Rosenberger 1960. Taxonomical research suggests that haptophytes P. parvum and P. patelliferum represent different generations rather than separate gene pools, both belonging to the species P. parvum (Larsen 1999).…”

Mitigating Fish-Killing Prymnesium parvum Algal Blooms in Aquaculture Ponds with Clay: The Importance of pH and Clay Type

“…Blooms are characterized by their seasonal recurrence, rapid proliferation, wide salinity and temperature tolerance, as well as the production of highly potent ichthyotoxins, the chemical nature of which remains incompletely known [5][6][7]. Recurring Prymnesium parvum blooms have become a routine problem for the Israeli Tilapia [8,9], the Texas striped bass [4,5] and, more recently, (June/July, 2009) the barramundi (Lates calcarifer) pond-based aquaculture industry in tropical Australia [2].…”