Baltimore Ecosystem Study Cary Institute of Ecosystem Studies

2012 BES Annual Meeting Presentation and Poster Abstracts

Factors Influencing Blooms of Sphaerotilus Natans in the Lower Jones Falls
Levery, Robert
Co-Authors: Stanley Kemp Wolf Pecher

Abstract: The objective of this study was to determine the factors responsible for an ongoing filamentous bloom of Sphaerotilus natans on the Lower Jones Falls. Physical data, nutrient data, benthic invertebrate samples, and bacterial samples collected were taken at regular intervals at sites upstream and downstream of the location during summer 2012. At the site exhibiting S. natans filamentous bloom growth, dissolved oxygen and pH were significantly lower than at upstream and downstream sites. Between sites, no significant differences were found for nutrients or bacterial counts, although there was a strong non- significant trend for Enterococcus counts that were higher at both downstream sites, possible indicating sewage infiltration between the upstream site and the S. natans site. The pH levels were significantly lower at the S. natans site than the other two sites. This is important because the pH levels observed at the site containing the bloom are in the optimal range for S. natans growth. There was a significant temporal difference in the Hilsenhoff Biotic Index for benthic samples, although no significant differences between sites were observed. All scores improved in the later sample, in part due to lower numbers of pollution intolerant invertebrates such as Oligochaetes and Chironomids. Anecdotal observations at other sites during the course of the study found emergent S. natans blooms at heavy infiltration of sewage. This implicates that S. natans is present throughout the Jones Falls and that sewage, pH, and dissolved oxygen are correlated with periodic blooms.