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Benthic, microscopic algae are the main drivers of primary productivity in streams. The relationship between the abundance and productivity of benthic algae in streams and lakes and the availability of limiting nutrients, especially soluble reactive phosphorus (SRP), has been extensively studied (reviewed in Allan and Castillo 2007, Larned 2010). However, nearly all of this research has been conducted on the periphyton assemblage found on hard substrates (e.g., stones, wood), while very little work has addressed the factors affecting the abundance of epipelic algae (i.e., the algae associated with depositional (soft) sediments such as sands and silts). One of the few studies conducted on epipelic periphyton (e.g., Vadeboncoeur et al. 2006) documented an interesting pattern in the abundance of benthic algae in temperate zone lakes. They found that the abundance of epilithic algae (i.e., algae growing on stones) was positively correlated with lake total phosphorus concentration (TP). That is, lakes with high TP had relatively high epilithic periphyton abundance, which suggests that the biomass and productivity of epilithic algae in temperate lakes is limited by the availability of phosphorus. Interestingly, a similar correlation was not observed for epipelic periphyton. Epipelic periphyton biomass was not correlated with TP and, surprisingly, it was significantly greater than epilithic biomass at all levels of TP observed. Chlorophyll a density is a surrogate measure for biomass, and has a molecular weight of 895 g/mol. Vadeboncoeur et al. (2006) found that chlorophyll a density on sediments was 5 to 100 times greater than chlorophyll density on rocks and wood.
The main objective of this study was to determine if similar patterns characterize benthic algal communities in streams. This research studied three main objectives. The first objective was to determine if patterns in the abundance of periphytic algae on hard and soft substrates in streams were similar to those found in lakes. (Vadeboncoeur et al. 2006) The second objective was to document the variability in epipelic periphyton biomass within streams, and compare and contrast that with within-stream variability in epilithic periphyton biomass. The third objective was to determine whether epipelic periphyton biomass was correlated with abiotic environmental variables such as light availability, water depth, and sediment particle size composition. This study includes a detailed analysis of multiple streams in the Kalamazoo River watershed in terms of the abundance of benthic algae on hard and soft sediments. This study will be used to compare to the minimal amount of research conducted in lakes in comparing the two different biota habitats. Larned (2010) suggested that the abundance of periphyton is based on five key aspects of environmental variation. The five aspects include: disturbances, stressors, resources, hydraulic conditions, and biotic interactions. This study focuses on abiotic factors that may influence epipelic periphyton biomass.
Wright, Courtney, ""Patterns in the Abundance of Benthic Algae in Streams"" (2016). Honors Theses. 2734.
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