Photosynthesis–light relations of stream periphyton communities

The photosynthesis-irradiance (P-Z) relationship was examined in 10 intact periphyton communities from sites in eight streams that differed in ambient light, nutrient concentrations, and grazing pressure. Algal biomass ranged from 2.3 to 86 pg Chl a cm -* and taxonomic composition differed. Photoassimilation of 14C was measured in the laboratory at six light levels for each community. Photosynthesis by communities from shaded sites was photoinhibited at the highest light level. The light intensity at the onset of saturation (Zk) was positively correlated (P 5 0.05) with ambient light, but ranged only from - 100 to 400 pmol m-* s-l among communities. Lightsaturated, Chl-specific photosynthetic rates (PSChl M) ranged ffrom 0.26 to 1.4 pg C &g Chl a)-’ h-‘. The initial slope (a) of the P-Z response ranged from 0.80 to 6.4 pg C (mg Chl a)-’ (pmol quanta)-’ rr-* s-l. Unlike phytoplankton, (Y and PS, (per unit Chl a) of the periphyton communities were not well related to the ambient light environment and tend.ed to be lower for communities from high-light habitats. Further, the P-Z responses of the communities were better related to periphyton biomass than to the light environment. Self-shading and other aspects of development in a matrix seem to be important determinants of periphyton P-Z relationships.

[1]  Trevor Platt,et al.  Photoinhibition of photosynthesis in natural assemblages of marine phytoplankton , 1980 .

[2]  K. Sand‐Jensen.  Physical and chemical parameters regulating growth of periphytic communities , 1983 .

[3]  Walter R. Hill,et al.  Community development alters photosynthesis‐irradiance relations in stream periphyton , 1991 .

[4]  D. T. C. Friend.  A Simple Method of Measuring Integrated Light Values in the Field , 1961 .

[5]  B. Paul,et al.  PHYSIOLOGICAL MODIFICATIONS RELATED TO DENSITY INCREASE IN PERIPHYTIC ASSEMBLAGES 1 , 1987 .

[6]  G. F. Humphrey,et al.  New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton , 1975 .

[7]  M. Bothwell,et al.  Photosynthetic characteristics of lotic periphyton , 1986 .

[8]  M. S. Adams,et al.  Seasonal variations in photosynthetic response of algae epiphytic on Myriophyllum spicatum L. , 1982 .

[9]  William H. McDowell,et al.  Elemental Dynamics in Streams , 1988, Journal of the North American Benthological Society.

[10]  C. Hudon,et al.  The Effect of Light on the Vertical Structure of Epibenthic Diatom Communities , 1983 .

[11]  Katherine Richardson,et al.  ADAPTATION OF UNICELLULAR ALGAE TO IRRADIANCE: AN ANALYSIS OF STRATEGIES , 1983 .

[12]  R. Wetzel,et al.  Boundary-layer and internal diffusion effects on phosphorus fluxes in lake periphyton1 , 1987 .

[13]  Paul G. Falkowski,et al.  Physiological responses of phytoplankton to natural light regimes , 1984 .

[14]  A. Jassby,et al.  THE RELATIONSHIP BETWEEN PHOTOSYNTHESIS AND LIGHT FOR NATURAL ASSEMBLAGES OF COASTAL MARINE PHYTOPLANKTON 1 , 1976 .

[15]  J. Meulemans.  Seasonal changes in biomass and production of periphyton growing upon reed in Lake Maarsseveen I , 1988, Archiv für Hydrobiologie.

[16]  G. Hornberger,et al.  The relationship between light and photosynthetic rate in a river community and implications for water quality modeling , 1976 .

[17]  B. Paul,et al.  Nutrient cycling in the epilithon of running waters , 1989 .

[18]  K. Sand‐Jensen,et al.  Photosynthesis and light adaptation in epiphyte-macrophyte associations measured by oxygen microelectrodes1 , 1987 .

[19]  J. Strickland.  A practical hand-book of seawater analysis , 1972 .

[20]  T. Parsons,et al.  A practical handbook of seawater analysis , 1968 .

[21]  R. Carpenter,et al.  Relationships between primary production and ii radiance in coral reef algal communities1 , 1985 .

[22]  J. Costerton,et al.  River epilithon: toward a structural-functional model , 1984 .

[23]  Some factors affecting primary productivity of stream riffle communities , 1975 .

[24]  Trevor Platt,et al.  Mathematical formulation of the relationship between photosynthesis and light for phytoplankton , 1976 .

[25]  P. Falkowski,et al.  Primary production and photoadaptation in light- and shade-adapted colonies of the symbiotic coral, stylophora pistillata , 1984, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[26]  T. G. Owens,et al.  Light: shade adaptation , 1980 .

[27]  B. Paul,et al.  An evaluation of the metabolism of sestonic and epilithic communities in running waters using an improved chamber technique , 1989 .