Resource synergy in stream periphyton communities

Journal Article · Tue Mar 01 04:00:00 EST 2011 · Journal of Ecology

DOI:https://doi.org/10.1111/j.1365-2745.2010.01785.x· OSTI ID:1015086

Hill, Walter ^[1]; Fanta, S E ^[2]; Roberts, Brian J ^[3]; Francoeur, Steven N ^[4]

---

1. University of Illinois, Urbana-Champaign
2. University of Illinois
3. ORNL
4. Eastern Michigan University, Ypsilanti, MI

1. Light and nutrients play pivotal roles in determining the growth of autotrophs, yet the potential for synergistic interactions between the two resources in algal communities is poorly understood, especially in stream ecosystems. In this study, light and phosphorus were manipulated in large experimental streams to examine resource colimitation and synergy in stream periphyton. 2. Whole-stream metabolism was simultaneously limited by light and phosphorus. Increasing the supply of either light or phosphorus resulted in significant increases in primary production and the transformation of the streams from heterotrophy to autotrophy. 3. Resource-driven changes in periphyton community structure occurred in concert with changes in production. Algal assemblages in highly shaded streams were composed primarily of small diatoms such as Achnanthidium minutissima, whereas larger diatoms such as Melosira varians predominated at higher irradiances. Phosphorus enrichment had relatively little effect on assemblage structure, but it did substantially diminish the abundance of Meridion circulare, a diatom whose mucilaginous colonies were conspicuously abundant in phosphorus-poor, high-light streams. Bacterial biomass declined relative to algal biomass with increases in primary productivity, regardless of whether the increases were caused by light or phosphorus. 4. Synergistic effects on primary production appeared to occur because the availability of one resource facilitated the utilization of the other. Light increased the abundance of large diatoms, which are known to convert high concentrations of nutrients into primary production more effectively than smaller taxa. Phosphorus enrichment led to the replacement of Meridion circulare by non-mucilaginous taxa in phosphorus-enriched streams, and we hypothesize that this change enabled more efficient use of light in photosynthesis. Higher ratios of chlorophyll a : biomass in phosphorus-enriched streams may have also led to more efficient photon capture and higher photosynthetic rates. 5.Synthesis. Our results underscore the potential for resource colimitation, even in habitats where a single resource is as strongly limiting as is light in shaded streams. The capacity of autotrophic communities to respond to more than one limiting resource suggests that prevailing single-resource models of ecosystem productivity are overly simplistic.

• Research Organization: Oak Ridge National Laboratory (ORNL); Oak Ridge National Environmental Research Park
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1015086
• Journal Information: Journal of Ecology, Journal Name: Journal of Ecology Journal Issue: 2 Vol. 99; ISSN 0022-0477; ISSN JECOAB
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
ABUNDANCE
AUFWUCHS
AUTOTROPHS
AVAILABILITY
Algae
BIOMASS
CAPACITY
CHLOROPHYLL
COMMUNITIES
DIATOMS
ECOSYSTEMS
METABOLISM
NUTRIENTS
PHOSPHORUS
PHOTONS
PHOTOSYNTHESIS
POPULATIONS
PRODUCTION
PRODUCTIVITY
SYNTHESIS
TRANSFORMATIONS
aquatic plant ecology
bacteria
community structure
light
phosphorus
primary production
resource synergy
streams