Flow, nutrients, and light availability influence Neotropical epilithon biomass and stoichiometry

Tyler J. Kohler, Thomas N. Heatherly, Rana W. El-Sabaawi, Eugenia Zandonà, Michael C. Marshall, Alexander S. Flecker, Catherine M. Pringle, David N. Reznick, Steven A. Thomas

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Light, nutrient availability, and flow are strong factors controlling the elemental composition and biomass of epilithon in temperate stream ecosystems. However, comparatively little is known about these relationships in tropical streams. We investigated how gradients of light and nutrient availability, seasonality, and habitat influenced epilithon biomass, chlorophyll a, and nutrient ratios in montane streams of Trinidad, West Indies. We sampled 4 focal tributaries of a single river, 2 of which had canopies experimentally thinned, every other month over a 2-y period to observe temporal dynamics and light effects on epilithon. We also sampled 18 sites across Trinidad's Northern Range Mountains once each in a wet and dry season to examine the effects of naturally occurring differences in light and dissolved nutrient availability on epilithic characteristics. We found greater chlorophyll a concentrations in habitats with greater light availability, but the effect of light on epilithon stoichiometry differed between the site-survey and focal-tributary data. In general, epilithic Cnutrient ratios decreased with increasing dissolved nutrient concentrations, but relationships between nutrient availability and biomass probably were obscured by naturally high dissolved N and P concentrations in many of the streams. Season and habitat type had profound effects on epilithon variables. Biomass and % C generally decreased in riffles and under wet-season conditions. These results suggest multiple controls for the quantity and quality of stream epilithon and have important implications for in-stream consumers.

Original languageEnglish (US)
Pages (from-to)1019-1034
Number of pages16
JournalFreshwater Science
Volume31
Issue number4
DOIs
StatePublished - Dec 2012

Keywords

  • Trinidad
  • algae
  • disturbance
  • light:nutrient hypothesis
  • periphyton
  • streams

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology

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