Life history of benthic macroinvertebrates: Studies and applications to freshwater ecology

Abstract

Life history, morphological, and behavioral characteristics of an organism are shaped by the abiotic and biotic features of its habitat. Using biological traits of benthic macroinvertebrates, I tested ecological predictions related to longitudinal zonation in the Fraser River, British Columbia, Canada. Voltinism, locomotion abilities, and feeding traits responded as predicted; however, some responding traits imply phylogenetic, rather than ecological correlation among biological traits.

Features of the life history of an organism may be spatially or temporally variable. I studied the life history of the caddisfly Neophylax rickeri (Trichoptera: Uenoidae) in two streams in Marin Co., California. The life cycles of N. rickeri differed between the two streams: in one, populations are univoltine, with a long summer prepupal diapause, and a fall emergence period; in the other, populations exhibit a split cohort (univoltine, bivoltine), without a long diapause, and year-round emergence. In a third Marin Co. stream, studies of pupae and adult emergence of N. rickeri revealed that male to female sex ratios shifted from 2:1 to 1:1 over the emergence period demonstrating protandry, with males preceding females by ∼2 weeks.

Life history case studies are a prerequisite for studying biological traits. To quantify available literature, I surveyed life history studies of Trichoptera, summarizing the aspects studied. I found that topics of life cycle timing and growth were most frequently studied, and behavior, adult biology, and early life stages were most understudied.

Biomonitoring models constructed using biological traits have the potential to indicate functional shifts in communities in response to disturbance. Using the Fraser River, B.C. dataset, I compared the accuracy, precision, and sensitivity of traits- and taxonomic-based biomonitoring models (species and genus level). I found that traits-based models accurately detected impairment; however, species-level taxonomic models had the highest overall performance.

Biological traits may be correlated as a result of phylogeny. Using biological traits of Trichoptera, I examined this question by calculating null-model distributions of "Steps In Character" analysis and the consistency index. I found that morphological, reproductive, and feeding traits were the most conserved phylogenetically and that voltinism and habitat size were the most labile.