Associations among selected physico-chemical parameters and Simuliidae (Diptera) from 23 lake-outlet sites in Newfoundland

• Main Author: Pérez, J. M. (José M.)
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1999
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/9072/; https://research.library.mun.ca/9072/1/Perez_JoseMari.pdf

The association between anthropogenic inputs, often the result of human activity within a watershed, and the structure of the simuliid community were investigated. The environmental analyses showed statistically significant regional and site differences related to the chemical stream variables, but the approach used showed no statistically significant differences in the physical stream variables, except for proximate vegetative cover and physical disturbance scores. The site differences in St. John's were attributed to urbanisation, but the site differences in the other regions could not be associated to specific environmental variables. -- Simuliids were selected for study because they have a passive filter-feeding stage which is susceptible to disturbances associated with increased human activities within a watershed and natural disturbances associated with stream processes. These relationships were investigated using 21 environmental variables correlated to pooled taxa richness, pooled taxa abundance, and final-instar head capsule size using univariate and multivariate statistical methods. -- The biological analyses showed no statistically significant differences in the pooled taxa richness and pooled taxa abundance per region. However, there were statistically significant site differences in the pooled taxa richness and pooled taxa abundance. These differences were correlated to SO₄²⁻, K⁺, Zn²⁺, and Cu²⁺ concentrations. The multivariate analyses, which statistically grouped chemical, physical, and biological variables into composite variables, showed a negative correlation between principal components Environmental Factor III (SO₄²⁻ and Cu²⁺ ion concentrations) and Presence/Absence Factor I (absence of Simulium decorum, S. tuberosum, Eusimulium canonicolum, Stegoptema mutata, and Prosimulium mixtum/fuscum complex). Principal component Environmental Factor III was also negatively correlated to principal component Abundance Factor I (scarcity of P. mixtum/fuscum complex, Cnephia omithophilia, and Simulium ...