Efficiency of using green algae as biological controllers against toxic algal taxa in cultured Nile tilapia Oreochromis niloticus, based on histopathological examinations

  • SM Aly
  • EM Ali
  • AA Dessouki
  • AA Dawah

Abstract

The incidence of harmful cyanobacterial blooms in surface waters has increased in frequency and outbreaks have become more severe. This research aimed at studying the effect of a culture of two green algal species as biological control of the growth of toxic blue-green algae. Nile tilapia of an initial mean weight of 55 g fish−1 (SE 5) were used for each of four treatments in triplicate. All algal seedings were done at 4 × 103 cells ml−1. Treatment I (untreated) served as a control, Treatment II was seeded with Microcystis aeruginosa, Treatment III was seeded with green algae Chlorella ellipsoidea and Scenedesmus bijuga, and Treatment IV was seeded with a mixture of M. aeruginosa and C. ellipsoidea and S. bijuga. After 10 days, Treatment IV showed 3.4% viable cell survival, compared to 35% and 55% in Treatments II and III, respectively. Histopathological examination revealed mild degenerative changes and focal necrosis, as well as a depletion of haematopoietic tissues in Treatment IV compared to Treatment II. These findings suggest the efficacy of C. ellipsoidea and S. bijuga in controlling the growth of M. aeruginosa and minimising its side effects on cultured Nile tilapia.

Keywords: blue-green algae, fish culture, histopathology, microcystin, toxicity

African Journal of Aquatic Science 2014, 39(4): 443–450

Author Biographies

SM Aly
Department of Pathology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
EM Ali
Department of Environmental Sciences, Faculty of Sciences, University of Suez, Suez, Egypt
AA Dessouki
Department of Pathology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
AA Dawah
Department of Limnology, Central Laboratory for Aquaculture Research, Abbassa, Sharkia, Egypt
Published
2015-04-01
Section
Articles

Journal Identifiers


eISSN: 1727-9364
print ISSN: 1608-5914