The role of cyanobacteria in the primary succession of an abandoned limestone quarry
Nicole R. Stone and Dana A. Dudle
Biology Department and Science Research Fellows Program, DePauw University, Greencastle, IN 46135
Primary succession is the process by which barren, soil-less regions, such as the abandoned limestone quarry within DePauw’s Nature Park, are first colonized. Cyanobacteria likely play an important part in the progression of such developing communities, through their abilities to stabilize organic material and sediment with their sticky sheaths, to help slow evaporation of water in dry environments, and especially to fix atmospheric nitrogen into a form usable by plants.
Do nitrogen-fixing cyanobacteria exist in the quarry only in wet, marshy areas covered by visible biocrust, or are they present in a broader range of terrain and a larger portion of the quarry bottom? Here we begin an investigation of the distribution and abundance of cyanobacteria, comparing places where colonizing plants are thriving to the quarry landscape more generally.
We chose 120 sites in the quarry bottom, 60 chosen to maintain an even distribution of sample sites throughout the quarry and 60 for the presence of Apocynum cannabinum. From these sites we collected moisture data and substrate samples. Cultures of these samples were cultured and monitored for cyanobacterial growth over a period of one week.
The vast majority of sample sites exhibited the presence of cyanobacteria by the end of one week, but sites chosen for the presence of Apocynum cannabinum generally yielded higher levels of both cyanobacteria and moisture.
Opportunities for future study include exploration of cyanobacteria’s nitrogen contribution to the quarry and their potential benefit to quarry vegetation, especially pioneer species such as A. cannabinum that often live in close conjunction with biocrust containing cyanobacteria.