Harmful Algal Blooms in Ponds: Causes, Concerns, and Management Eugene Braig, OSU Extension, School Program Director, of Environment and Aquatic Ecosystems Natural Resources OHIO STATE UNIVERSITY EXTENSION Harmful Algal Blooms in Ponds • What is this stuff!? • What causes it? • Concerns • Management strategies OHIO STATE UNIVERSITY EXTENSION What is this stuff!? • Cyanobacteria are ordinarily responsible for harmful algal blooms (HABs). • Not true algae: Cyanobacteria are often called “blue-green” algae. • They are now recognized as bacteria that contain chlorophyll and are capable of photosynthesis. • Cells of most species grow together in colonies. • Most are capable of fixing their own nitrogen from the atmosphere using specialized cells called heterocytes. • Without the need for N compounds as nutrients, P enrichment can favor cyanobacteria blooms. • A bloom is simply an abundant or excessive growth of algae or cyanobacteria. OHIO STATE UNIVERSITY EXTENSION What is this stuff!? OHIO STATE UNIVERSITY EXTENSION The major HAB players • Microcystis P h o ot • Colonies of small, spherical, c r e bright green globs that vary d M :ti buoyancy to seek optimal light e ! conditions. • Can turn the water column green or form large green slicks on the surface. • Patches of turquoise and white foaminess often appear. CP rh • Cannot fix nitrogen. ao • By far the most common to Ohio drofw oterc pwoantedrss a(nthde w “Mesikteer”n o Lf a“Aken nEieri,e PE oihO , :ti dmiJ A Fannie, and Mike”). OHIO STATE UNIVERSITY EXTENSION The major HAB players • Planktothrix (some species used to be known as Oscillatoria) • Colonies of planktonic filaments that distribute through the water. • Often appears as classic dark- colored “blue-green” water but some species have a reddish- brown hue. • Can be associated with an oily- looking surface film. • Cannot fix nitrogen. Photo credit: Linda Merchant-Masonbrink, Ohio EPA • Recently very common to Ohio’s reservoirs and inland waters. OHIO STATE UNIVERSITY EXTENSION The major HAB players • Aphanizomenon • Colonies of planktonic filaments that often bundle together and look like tiny grass clippings. • Fixes atmospheric nitrogen in heterocytes. • Sometimes sold as a dietary supplement. However, the supplement is not regulated and may contain cyanobacterial toxins. Consumers beware! Photo credit: US Fish & Wildlife • The third of the three historically Service, Klamath Falls, OR dominant species in Lake Erie (the - phani- of “Annie, Fannie, and Mike”). OHIO STATE UNIVERSITY EXTENSION The major HAB players • Oscillatoria (and related benthic species) • Colonies of rather globby-looking filaments growing on pond substrates. • Often form mats along the bottom that float to the surface later in the growing season. • Lacks specialized cells but still fixes nitrogen from the atmosphere. Photo credit: Frank Gibbs • Very common to shallow waters of ponds and relatively tolerant of low- light conditions. OHIO STATE UNIVERSITY EXTENSION The major HAB players BP rh dio megc ot r ae nd U ,sti revin :T .rD • Lyngbya o ytismoh (the outdated name Plectonema T fsa o el is still sometimes used) d o • Colonies of clustered filaments, usually visible to the naked eye. • Often form dense mats along the bottom that float to the surface later in the growing season. • Lacks specialized cells but still fixes nitrogen from the atmosphere. • One of Ohio’s recently problematic species (specifically Lyngbya wollei), especially on Maumee Bay near Toledo. OHIO STATE UNIVERSITY EXTENSION The major HAB players • Cylindrospermopsis • Colonies of planktonic filaments that distribute through the water column. • Fixes nitrogen and can be distinguished from Planktothrix by teardrop-shaped heterocytes. Photo credit: David Patterson and Bob • A recent invader to Ohio’s Lake Andersen, Provasoli-Guillard Center Erie waters and Buckeye Lake.