Integration of zootechnical and ecological factors to evaluate the physiological well-being of Penaeus vannamei on farms connected to Lake Maracaibo, Venezuela

The semi-intensive commercial shrimp farming in Lake Maracaibo, Venezuela, is affected by eutrophication processes resulting from excess nutrients, which favor the proliferation of microalgae and the deterioration of water quality. There is limited information on the relationship between production variables, fluctuations in planktonic communities, and their impact on the physiological state of the shrimp. Therefore, the objective of this study was to analyze the relationship between production and ecological variables with the Relative Condition Index (RCI) as a physiological indicator of Penaeus vannamei during a ten-week grow-out cycle. Production and ecological variables were monitored weekly, including qualitative and quantitative analyses of phytoplankton and zooplankton. Data were evaluated using Pearson correlation, variable selection with VIF and AIC, logistic regression with Firth's bias reduction, and deviance analysis. Shrimp exhibited a final average CRI of 1.36 ± 0.92 and an average ICA of 1.81 ± 0.89. The phytoplankton community was dominated by Cyanobacteria (57.8%), followed by Chlorophyta (32.4 %) and Heterokontophyta (9.1 %), while zooplankton was primarily represented by copepods (69.9 %). However, the model showed a positive association between CRI and the abundance of Chlorella sp. and barnacle nauplii, and a negative relationship with Mesocyclops sp. These results suggest that the nutritional and functional quality of plankton may be more relevant than its total abundance, constituting a bioindicator of physiological well-being and a potential supplementary food source.