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Table 4 Generalized additive model of location, shape and scale (GAMLSS) fits for mean abundance of Gyrodactylus cichlidarum (MAG; dependent variable) in Nile tilapia farms in Yucatán state. The best model was selected using a stepwise procedure and the lowest values of Akaike information criterion (AIC) and global deviance. The final model was: MAG ~ cs(Do) + cs(Tc) + Qa + Pt where cs is a cubic spline smooth function, and those independent variables without smoother had a linear relationship with the dependent variable (MAG)

From: Geographical distribution of protozoan and metazoan parasites of farmed Nile tilapia Oreochromis niloticus (L.) (Perciformes: Cichlidae) in Yucatán, México

Model

Degrees of freedom (df)

Global deviance

Deviance explained (%)

AIC

P (0.05)

(Null model) MAG ~ 1

-

130.82

-

132.82

5.4e-6*

MAG ~ cs(Do)

df =16

100.52

23.16

110.51

0.0002*

MAG ~ cs(Do) + cs(Tc)

df =16

92.65

29.17

110.65

0.0059*

MAG ~ cs(Do) + cs(Tc) + Qa

df =19

86.29

34.03

106.29

0.0208*

MAG ~ cs(Do) + cs(Tc) + Qa + Pt

df =17

48.05

63.27

74.05

0.0001*

  1. Abbreviations: Do Dissolved oxygen (mg/l), Tc Tank capacity (m3), Qa Use of quarantine area, Pt Use of prophylactic treatments
  2. *P value < 0.05