Date of Award

2015-01-01

Degree Name

Master of Science

Department

Geology

Advisor(s)

Vanessa L. Lougheed

Abstract

In many regions around the world climate is changing and biotic communities are changing with it. In areas like the southwestern U.S., drought is one of the major sources of disturbance. Although droughts are an integral part of the natural hydrological cycles, they can have devastating effects on freshwater ecosystems when disrupted by extended periods of drought, resulting in changes to the structure and function of biotic communities. In this study, we surveyed four streams in the Sacramento Mountains of New Mexico from 2010 to 2014: Agua Chiquita, Rio Peñasco, Wills Creek, and the Sacramento River; These years encompassed an average wet year, an exceptionally dry year, and two years following the exceptionally dry conditions. We wanted to determine how low water availability influenced community composition and found only minor changes to community function only to the collector functional group. We also wanted to determine where macroinvertebrates recolonized from after a major disturbance event. We found that the sampled sites were highly nested with nearby springs, which provided refuge during harsh conditions. Regional predictors for community composition in cool-water streams, desert springs, desert wetlands and the Rio Grande were analyzed. We used family-level, presence-absence data from 6 different studies in south-central New Mexico and west Texas. Using Non-metric Multidimensional Scaling (NMDS) analysis, we found temperature, salinity, and dissolve oxygen were strong predictors for community composition. Desert sites were best predicted by high temperature and salinity, while cool water sites were predicted by high dissolved oxygen and low temperature. At the genus-level we found the same environmental variables predicted community composition as well as phytoplankton, however; the higher taxonomic resolution may have masked the effect of this variable in the family-level analysis. Dry conditions in the southwestern U.S. are expected to persist and possibly intensify, therefore, monitoring these sites is vital to track changes to community composition as they may have important implications for transitioning regions around the world.

Language

en

Provenance

Received from ProQuest

File Size

89 pages

File Format

application/pdf

Rights Holder

Ector Matias Martell

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