Secrets in Slime: Identifying Nitrogen-Fixing Cyanobacteria

Sarah Baker, St. Catherine University
Paula Furey, St. Catherine University

Abstract

Algae, primary producers that form the base of aquatic food webs, serve as ecological indicators of water quality. Cyanobacteria, a group of algae, can indicate a nutrient rich environment, are known to produce toxins that can be harmful, and, relative to other types of algae, are less edible or poorer food quality for grazers which can effect food web dynamics. Additionally, some cyanobacteria can fix atmospheric nitrogen and thus play an important ecological role in bringing nitrogen into aquatic ecosystems, especially those that might be nitrogen poor. Despite their importance in ecology and their value as bioindicators, algae, including cyanobacteria, are often overlooked or underrepresented in studies or monitoring done by researchers or agencies because of limited knowledge or challenges in learning algal identification. The goal of this poster is to inform ecologists and water quality specialists about how to identify cyanobacteria, particularly N2-fixing species (cyanobacteria and diatoms with cyanobacterial endosymbionts). Using examples of algae collected from nitrogen-poor, geothermally heated streams in Iceland, we present detailed microscope photos to highlight features important for algal identification such as macroscopic and microscopic shapes (overall and cellular), sizes (cell lengths and widths), and microscopic growing patterns. Images demonstrate variations in size, shape, color, frequency, and location of different cell types including vegetative cells, heterocytes (N2-fixing cells), and akinetes (resting spores). Knowing which cyanobacterial species are present, especially those that fix nitrogen, can provide ecologists and water quality specialists with more detailed insight into the ecology and quality of aquatic ecosystems which will strengthen our ability to predict and protect our freshwaters in a changing world.

 

Secrets in Slime: Identifying Nitrogen-Fixing Cyanobacteria

Algae, primary producers that form the base of aquatic food webs, serve as ecological indicators of water quality. Cyanobacteria, a group of algae, can indicate a nutrient rich environment, are known to produce toxins that can be harmful, and, relative to other types of algae, are less edible or poorer food quality for grazers which can effect food web dynamics. Additionally, some cyanobacteria can fix atmospheric nitrogen and thus play an important ecological role in bringing nitrogen into aquatic ecosystems, especially those that might be nitrogen poor. Despite their importance in ecology and their value as bioindicators, algae, including cyanobacteria, are often overlooked or underrepresented in studies or monitoring done by researchers or agencies because of limited knowledge or challenges in learning algal identification. The goal of this poster is to inform ecologists and water quality specialists about how to identify cyanobacteria, particularly N2-fixing species (cyanobacteria and diatoms with cyanobacterial endosymbionts). Using examples of algae collected from nitrogen-poor, geothermally heated streams in Iceland, we present detailed microscope photos to highlight features important for algal identification such as macroscopic and microscopic shapes (overall and cellular), sizes (cell lengths and widths), and microscopic growing patterns. Images demonstrate variations in size, shape, color, frequency, and location of different cell types including vegetative cells, heterocytes (N2-fixing cells), and akinetes (resting spores). Knowing which cyanobacterial species are present, especially those that fix nitrogen, can provide ecologists and water quality specialists with more detailed insight into the ecology and quality of aquatic ecosystems which will strengthen our ability to predict and protect our freshwaters in a changing world.