(8.6) FLORA and FAUNA - EPT Index and Plecoptera of the Ocklawaha River, Florida

The EPT Index and Plecoptera of the Ocklawaha River, Florida

An Information, Opinion, & Sources Report

Compiled by Ocklawahaman Paul Nosca

Created: 19 June 2013

Last Revised: 19 October 2020

NOTE: Some of the credible written works by others (i.e., magazine/newspaper articles, web pages, etc.) that are referenced in this report would not be considered "peer-reviewed" scientific documentation.


EPT is an acronym referring to the names of the following three orders of environmental indicator-species insects: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies).

The existence of the larvae of stoneflies (Order Plecoptera) in a Florida stream is an indication that its current flows swiftly and its water quality is good to excellent. Mayflies and caddisflies also are indicative of clean waters but do not require lotic (riverine) environments for their life processes.

Specimens of the Order Plecoptera, Family Perlidae, Species Neoperla clymene have been collected from swift-flowing segments of the Ocklawaha River basin.


NOTE: The Ocklawaha River is commonly misspelled as "Oklawaha" in many reports.

Beck (1965) "Streams of Florida":

"In my work I have found a descriptive terminology convenient for reporting velocities. Swift flow is that velocity in which Plecoptera are found in Florida. Moderate velocity is any velocity sufficient to maintain a population of Simuliidae (these are confined to running water in Florida). Any velocities below these two loosely defined levels are termed low. We have only recently obtained and started using velocity meters in our biological work. When the results of this work are available it will be interesting to see how well the actual measurements support the observed qualitative terminology."

"The Sand-Bottomed Stream:

"This is the most widely distributed and most frequently encountered type of stream in the state. It has been the most typical lotic feature of the area and is the one disappearing most rapidly with the alteration of drainage patterns. The sand-bottomed stream is a prominent feature of the Central Highlands (see Cooke, 1939, for a discussion of the topographic regions of Florida)...Typical faunal elements are...Plecoptera...Of all the lotic habitats this is the most typically so."

"Chemically and physically the sand-bottomed stream is mildly acid to circum-neutral (pH 5.7-7.4), has alkalinity ranging 5 to 100 mg/L, hardness from 5 to 120 mg/L, color moderate to high, and of moderate to swift velocity. Bottom deposits consist of fine sand with varying amounts of leaf and other organic detritus in the quieter reaches. Areas of limestone outcroppings are frequent. In the western panhandle the sand-bottomed streams are usually swifter and have coarser bottom deposits. Shifting sand bottoms are common. Plant growth may be slight to quite dense and of great variety."

"The Calcareous Stream:

"These streams are predominantly of spring origin and many of the finest examples have been carefully protected because of their beauty. Visitors to Florida find these a major attraction; a number of the larger springs and their runs have been developed commercially, and the natural aspects of most have been carefully preserved. These are, indeed, a striking sight with their cool, very clear waters, dense and varied growths of submerged plants, and banks shaded by large, moss-hung trees. The beauty of these streams is actually a limnologic feature in that it is the result of two factors; the clarity of the water itself and the high concentrations of phosphorous."

"Widely distributed in Florida, the calcareous stream is found in the Central Highlands..."

"The fauna of these streams is...represented by...and occasionally simuliids and Plecoptera."

"The waters are alkaline (pH 7.0-8.2), the alkalinity ranging from 20 to 200 mg/L, hardness from 25-300 mg/L (omitting the oligohaline and mesohaline springs of Whitford (1956)). The water is normally clear (some examples have a slight turbidity from small amounts of Montmorillonite clay in suspension) and generally low in color. Velocity ranges from low to swift."

"Bottom materials consist of sand, clay, limestone, and quite heavy deposits of organic detritus in the slower reaches. Submerged plant variety appears to be a function of bottom material."

Bass and Guillory (1976) "Cross Florida Barge Canal Restudy Report; Fisheries Study":

"Although the Oklawaha River is a 'sand-bottomed' type stream, as defined by Beck (1965), it has several unique characteristics. Its swift current and steep gradient of 60 feet from headwaters to its mouth more typically exemplifies a Piedmont-type stream.

Florida Department of Natural Resources (1992) "Oklawaha River Aquatic Preserve Interim Management Plan":

"Table 1. Some Invertebrate Classes and Orders of the Oklawaha....Order....Plecoptera....Common Name....Stoneflies"

Pescador, M. L.; A. K. Rasmussen; and B. A. Richard (2000) "A Guide to the Stoneflies (Plecoptera) of Florida":

"Stoneflies (Plecoptera) are a diverse group of insects that are primarily associated with clean, cool running waters. A few species, however, have radiated and adapted to life in oligotrophic, alpine and boreal lakes, intermittent streams (Stewart & Harper, 1996), and terrestrial but cool damp environments (Williams & Feltmate, 1992). The nymphs generally have their highest density in riffle areas of streams, where rocks, gravel, snags, and accumulated leaf packs abound. The ecological value of stoneflies in stream ecosystems has been well documented (Hynes, 1976; Stewart & Stark, 1988; Stewart & Harper, 1996), and their potential use as biological indicators of water quality is well known (Resh & Jackson, 1993; Lenat & Penrose,1996; Mauger, 1997; Morse et al.,1997; Barbour et al., 1999; Karr & Chu, 1999)."

"Based on invertebrate species composition, Florida has recently been classified into 3 geographic stream classes (bioregions) namely, the panhandle, northeast, and peninsular Florida (Barbour et al., 1996). Stoneflies are one of the most dominant groups of aquatic insects in the panhandle and northeast bioregions; approximately ninety percent of the stonefly fauna of Florida occur in these areas, a distributional pattern similar to that of cool-adapted mayfly and caddisfly taxa (Berner & Pescador, 1988; Pescador et al., 1995). Species richness in these two bioregions, which geographically represent North Florida, appears to be related to habitat diversity, current velocity, temperature, and proximity to rivers draining the Southeastern Nearctic Highlands and Coastal Plain."

"In addition to being diverse, the perlids are the most geographically widespread stonefly group in the state with the species, Neoperla clymene, extending its range as far south as the Manatee and Peace River basins."

"Perlid nymphs are found in a wide variety of lotic habitats ranging from small to moderate sized streams and rivers. In Florida, the preferred nymphal microhabitats include mostly leaf packs trapped between wood snags or broken branches of trees embedded into the stream substrata. The predominantly predatory nymphs commonly feed on other aquatic insects (e.g., chironomid midges, mayflies, caddisflies)."

"Appendix B includes a database of the spatial distribution and the seasonality of the 42 stonefly species known in the state. Interestingly, but not surprisingly, only 8 species: Acroneuria arenosa, Clioperla clio, Isoperla davisi, Isoperla sp. C, Leuctra rickeri, Nemocapnia carolina, Neoperla clymene, and Perlesta placida (complex) are known from the Florida peninsula. Neoperla clymene the most widely distributed stonefly species in the state has been recorded from Escambia River Basin and as far south as Manatee River and Peace River basins. The highest species diversity in the state occurs between the Choctawhatchee and Escambia river basins."

Watershed Science Institute (2000) "Watershed Condition Series, Technical Note 3, The EPT Index":

"The EPT Index is named for three orders of aquatic insects that are common in the benthic macroinvertebrate community: Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies). The EPT Index is based on the premise that high-quality streams usually have the greatest species richness. Many aquatic insect species are intolerant of pollutants and will not be found in polluted waters. The greater the pollution, the lower the species richness expected, as only a few species are pollutant tolerant."

"Common stonefly Plecoptera group. The common stonefly measures less than 1 inch in length (without tail), and has two wings, two sets of branched gills between the underside of the body, and yellow to brown color. The stonefly is not tolerant to low levels of dissolved oxygen and therefore prefers cold, swift-moving streams. Stoneflies are an important source of food for [mountain, cold-water] trout. The streamlined, flat body of stonefly nymphs enables them to move about the streambed in rapid currents."

Florida Department of Environmental Protection (FL DEP) (2001) "Deep Creek at CR 315, Putnam County, 8/9/00 and 11/14/01; Eco Summary BioRecon Report":

"Biorecons were performed at this site for several reasons. First, it is important to monitor the health of Deep Creek as a tributary of the Ocklawaha River, parts of which have been designated as Outstanding Florida Waters."

"One stonefly species, Neoperla clymene, was also collected here. Stoneflies are quite rare in the Florida peninsula, due to a combination of both natural and anthropogenic factors."

FL DEP (2007) "Development and Testing of Biomonitoring Tools for Macroinvertebrates in Florida Streams":

"Plecoptera, for example, are common in the panhandle but extremely rare in the peninsula, probably due to a combination of poor recruitment, warmer temperatures, and lower water velocities."

"Richness was calculated as the number of unique taxa found within a particular group, such as the Ephemeroptera, Plecoptera, or Trichoptera, or their combination (EPT)."

Meyer (2009) "Plecoptera; Stoneflies; General Entomology" webpage:

"Stoneflies require clean, well-oxygenated water to survive. They are extremely sensitive to water pollution and are used by ecologists as indicators of water purity. Stoneflies are also an important source of food for game fish (e.g., trout and bass) in cold mountain streams."

Encyclopedia of Life (2011) "Facts about Coastal Stone (Neoperla clymene)" [Coastal Stonefly] webpage:

"In Florida, it occurs in the Alafia, Apalachicola, Blackwater, Choctawhatchee Bay, Choctawhatchee, Escambia, Manatee, Ochlockonee, Oklawaha, Perdido, Santa Fe, St. Andrews Bay, St. Johns (lower), St. Marks, Suwannee, Tampa Bay, Waccasassa, and Yellow River drainages (Rasmussen et al., 2003)."


It is quite possible that most of Ocklawahaman Paul Nosca's favorite Florida, Georgia, Oklahoma, and Virginia freshwater bass and/or trout-fishing creeks and rivers probably contain some Plecoptera (stonefly) larval populations.


Bass, D. G. and V. Guillory. 1976. Cross Florida barge canal restudy report. Fisheries study (Volume I, II, III). Prepared for the U.S. Army Corps of Engineers by Florida Game and Fresh Water Fish Commission, Tallahassee, FL.

Beck, W. M. 1965. The streams of Florida. Bulletin of the Florida State Museum Biological Sciences, Vol. 10, No. 3, pp. 91-126. University of Florida, Gainesville, FL. http://ufdc.ufl.edu/UF00000096

Encyclopedia of Life (EOL). 2011. "Facts about Coastal Stone (Neoperla clymene)" webpage. EOL. http://eol.org/pages/612580/details

Florida Department of Environmental Protection (FL DEP). 2001. "Deep Creek at CR 315, Putnam County, 8/9/00 and 11/14/01; eco summary bio-recon report" webpage. FL DEP, Tallahassee, FL.


FL DEP. 2007. Development and testing of biomonitoring tools for macroinvertebrates in Florida streams. FL DEP, Tallahassee, FL.


Florida Department of Natural Resources (FL DNR). 1992. Oklawaha River Aquatic Preserve interim management plan adopted May 5, 1992. FL DNR, Tallahassee, FL. http://publicfiles.dep.state.fl.us/CAMA/plans/aquatic/OklawahaRiver.pdf

Meyer, J. R. 2009. "General Entomology. Stoneflies. Plecoptera." webpage. North Carolina State University, Raleigh, NC..


Pescador, M. L.; A. K. Rasmussen; and B. A. Richard. 2000. A guide to the stoneflies (Plecoptera) of Florida. 94 pp. Division of Water Resource Management, FL DEP, Tallahassee, FL.



U.S. Geological Survey (USGS). 2013. "Stoneflies of the United States. Stoneflies of Florida. Coastal Stone (Neoperla clymene)." webpage. USGS.

http://www.npwrc.usgs.gov/resource/distr/insects/sfly/fl/413.htm http://www.npwrc.usgs.gov/resource/distr/insects/sfly/index.htm

Watershed Science Institute. 2000. "Watershed condition series. Technical note 3. The EPT index." webpage. Watershed Science Institute, Natural Resources Conservation Service, U.S. Department of Agriculture.



Email: ocklawahaman1@gmail.com