Study Explores Tambaqui Sperm for Eco-Toxicological Testing Viability

Analyzing the viability of using cryopreserved semen from tambaqui Colossoma macropomum in ecotoxicological assays as a strategy for assessing the quality of aquatic environments is the goal of Professor Jadson Pinheiro Santos' research. The study, titled "Viability of Using Cryopreserved Semen of Tambaqui Colossoma macropomum (Cuvier, 1816) (Characiformes: Serrasalmidae) in Ecotoxicological Assays," was supervised by Professor Dr. Raimunda Fortes Carvalho Neta and is a result of his PhD in Biodiversity and Biotechnology from the BIONORTE/Uema network.

The research, which won an award at the VII Emanoel Gomes de Moura Prize for Theses and Dissertations at Uema, was conducted in fish farms in the municipalities of Santa Inês and Santa Rita and in the Biomarkers in Aquatic Environments and Animal Reproduction Biotechnologies laboratories at Uema.

"The idea to work on this topic arose from debates with my supervisor, Professor Raimunda Fortes, where we envisioned the possibility of combining my accumulated knowledge in studies on sperm biology and fish semen cryopreservation with the execution of ecotoxicological tests in aquatic environments, especially since I intended to pursue a PhD in the BIONORTE network," explained Jadson.

Two Key Perspectives

The research has two important perspectives: presenting an alternative technique by exposing sperm cells instead of using animals in ecotoxicological assays, and demonstrating possible alterations in the reproductive physiology of freshwater fish.

The study began with an analysis of biomonitoring in Brazil and adherence to the Sustainable Development Goals, followed by a systematic search for scientific articles on the subject. After the search, a preliminary screening was conducted based on content analysis of titles and abstracts.

In the second phase, ecotoxicological tests were conducted using seminal samples from sexually mature male tambaqui from a local fish farm. The semen was collected eight hours post-hormonal induction in graduated glass tubes. After an initial evaluation confirming no prior activation, the experiment was conducted in a factorial scheme, testing two pesticides used in agricultural systems (glyphosate and fenitrothion). Finally, the same experiment was performed using cryopreserved tambaqui semen.

Research Findings

The systematic bibliographic research indicated 25 fish species, predominantly Danio rerio (18%). Insecticides were present in 78% of the studies, mainly endosulfan (35%) and cypermethrin (13%). Reproductive endocrine disruptions were the most reported targets of action (57.5%).

In ecotoxicological tests, results showed that fresh semen samples exhibited an initial motility of 89.24% and an average duration time of 100 seconds (up to 10% sperm motility). Sperm motility significantly decreased after 30 seconds for both glyphosate and fenitrothion at all tested concentrations, except at 240 mg/L where no activation was observed.

For cryopreserved semen, there was a significant reduction in sperm motility immediately after exposure to glyphosate solutions at all tested concentrations compared to the control, with no significant differences between the tested concentrations.

According to Jadson, "The effects caused by pesticides on the reproduction of freshwater teleosts are evident, indicating the sensitivity of sperm cells to pesticides, demonstrating the potential use of cryopreserved tambaqui semen in ecotoxicological assays."