Sperm characteristics of Pseudoplatystoma reticulatum.

Spermatological parameters of the sperm of P. reticulatum were found rather variable and they are shown in Tab. 1. The parameters of osmolality, motility, and motility time were where the greatest variability was found, with pH and concentration being the least variable.

Seminal plasma composition of Pseudoplatystoma reticulatum. The results of the analysis of the seminal plasma are shown in Tab. 2. The seminal plasma of P. reticulatum is mainly composed of the Na + ion, followed by the Cl-, Ca + and K + ions, while the Mg 2+ ion showed the lowest values. Within the organic components, total protein and glucose stood out; on the other hand, fructosamine and triglycerides had low values.

Correlation between seminal plasma components and seminal characteristics of Pseudoplatystoma reticulatum. In the principal component analysis (PCA) to determine the possible relationships between the seminal plasma components and the sperm characteristics of this species, the first two components were chosen: the first component (PC1) explained 47.1% of the data variance and the second component (PC2) explained 21.42%, totaling 68.52% of the total variation of the data (Fig. 2).

The first two axes are obtained through the PCA and represented in Fig. 2, which can be observed in the colors from light blue to orange that indicate the percentage of contribution in the explained variance, with light blue for the lowest value and orange for the highest percentage. The graph shows a cluster between variables such as Mot, Mot.tm, and Conc, indicating a strong positive correlation between them and Sem.vol and Tot.pro. On the other hand, Frut and Osm had a high positive correlation, but a negative relationship with Mot, Mot.tm, Conc, Tot.pt, and pH. The Cl-, Ca +, Trig, Sem. Vol, and Tot.pro variables had a strong positive correlation with pH, while this variable had a strong negative correlation with K +, which in turn had a positive correlation with Osm and Frut. The variables Glic, Na + and Mg 2+ contributed little to the variance of the analyzed data, but the Na + and Mg 2+ had a strong negative correlation between them.