Advisor: Michael Bozek
Measurement of Lacustrine Littoral Zone Structure
The
majority of structural habitat in north temperate lakes exists in the
littoral zone. Littoral zones of lakes in north temperate regions harbor
high diversity of fauna species, have the high animal biomass and
density, and great secondary production. Littoral zones can be
structurally diverse among and within lakes providing a wide array of
habitat for aquatic organisms. Substrate of varying particle sizes,
macrophyte presence and morphology, and coarse woody debris are the
natural physical structure comprising microhabitats in littoral zones.
Substrates of larger particle size have more interstitial spaces
providing living areas for a variety of organisms. Emergent,
floating-leaf, and submergent macrophytes provide varying types of cover
based on differences in their morphology. Coarse woody structure also
provides cover and additional structure for accumulation of forage
material for fish and other aquatic organisms.Human-induced changes to riparian areas directly affect littoral zone habitat structure. Housing development along lakeshores has an effect on key lake characteristics, i.e. increased dissolved nutrients, higher invasion rates of non-native species, higher exploitation of fish by anglers, and changes in littoral zone habitat. Considering the ecological importance of the littoral zone and vulnerability to human modification, quantitative assessments of this shallow-water region for classification and protection are warranted.
However,
little work has been done to assess littoral zone structure and
integrate findings into generalized management applications. In
particular, research is lacking on how complex littoral zone habitats
are, how typologies can provide management frameworks, and understanding
the functional relation between habitat diversity and biotic diversity.
The objective of this study is to create multi-dimensional littoral zone
fingerprints of lakes in order to establish metrics for classification
of various habitat types. We quantified littoral zone habitat in several
north temperate lakes using quadrats placed along transects from shore
to 3m depth. Depth, slope, size and percent substrate cover, and plant
type and cover were visually estimated in square meter quadrats along 50
transects in each lake using snorkel gear. Coarse woody structure
abundance was measured within 10m of either side of the transects.
Multi-dimensional ordination of habitat features display the variation
in habitat occurring within and among lakes including the abundance of
simple, complex, common, and species-specific habitats. Results reveal
that clearly described patterns in littoral zone habitat can aid in
classifying, protecting and restoring littoral zone habitats in lakes.