Periphyton biomass and species composition in 21 British Columbia lakes: seasonal abundance and response to whole-lake nutrient additions

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Abstract
Periphyton communities on artificial substrates in 21 oligotrophic British Columbia lakes were sampled from 1978 to 1980. Periphyton biomass (ash-free dry weight (AFDW) and total chlorophyll (Chl)) and accumulation rates (milligrams AFDW per square metre per day) were among the lowest recorded from temperate oligotrophic lakes, averaging from 0.01 to 5.69 mg Chl∙m−2, 0.04 to 2.86 g AFDW∙m−2, and 1 to 47 mg AFDW∙m−2∙day−1. Diatoms were the dominant group in most lakes at most times, comprising over 70% of total periphyton biomass. Achnanthes minutissima and Tabellaria flocculosa were the most ubiquitous species in the study, and Eunotia spp. were common only in acidic humic-stained lakes. Of the physical and chemical factors measured in this study, pH appeared to be most important in regulating diatom species composition. In those lakes fertilized with nitrogen and phosphorus, periphyton biomass showed marked increases over untreated years, but the community species composition in most lakes remained similar between treated and untreated years. Comparisons between artificial and natural substrates showed that the same species were common on both substrates, although relative abundances varied. The littoral zone of most study lakes is small relative to the pelagic, and it is estimated that periphyton comprised < 1% of average total algal biomass (as chlorophyll) and also represented < 1% of estimated total annual carbon metabolism.