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OZARK STREAM COMMUNITY ECOLOGY
by Bryce L. Meyer
Trickling through the hills, dells, fields, and forests of sections of Missouri, Arkansas, and Oklahoma (see figure 1 for a map) are the usually clear brooks and streams of the Ozark Plateau (Ozark Plateaus Physiographic Province as per Pflieger 1989 from [SRWIA 2000], Ozark Aquatic Faunal Region (Pflieger 1997). These streams hold a unique wealth of temperate species both above their surfaces and in their surrounding floodplains and feeders, and in their cool waters. The ground surrounding and under these streams is dolomite rich, pockmarked by caves and sinks, which in turn contribute cold, slightly alkaline, waters, buffered with CaCO3 leeched from the limestone, with flint and chirt gravel (Pflieger 1997), bolder, and silt/sand bottoms. Many streams are surrounded by forests of oak, pine, and cedars, others by farm fields, and some even by prairie. The waters of the streams have a mixed personality: first, many streams begin as a sequence of small pools with connecting short races fed by seasonal ditches and seeps; next, a cooling flow of spring water is injected by a spring source (enhanced heavily if a dam tail water also feeds); finally, the stream slows into pools of increasing size, with sandbars, wide rocky races, and warmer backwaters. Many streams currently either contribute to a larger waterway (ending up in the Mississippi River System), or lead into large impoundments that dot the Ozark Region. This essay will endeavor to describe the basic aquatic community of these streams, to list the effects of several factors affecting composition and diversity of the community, and to lay out further treatments and research areas to better understand the community.
In beginning to look at the many ‘personalities’ of the Ozark stream and its denizens, we should start with the beginning of many Ozark streams: the cool water, high gradient small pools bounded by riffles at each end, fed by seasonal ditches and small seeps, with rock and root-reinforced soil and sand banks, and generally low stream order. This top potion is small enough in many areas to be fully shaded for much of the growing season by bank forests if present. The rocks on the bottom of this portion (Chirt, flint, limestone, dolemite) can be fist sized along the banks, with stretches of coarse gravel golf ball to pea-sized. The water temperature in most of the pools will reach over 75oF in the summer, and drop cold enough for surface ice in the winter in the smallest pools (though holding over 40oF at the bottoms). A stream very similar to this in Missouri is Dry Fork (a tributary of the Meramec River) and the portion of the Current river above Montauk State Park. The base of the food chain features filamentous green algae, unicellular phytoplankton (diatoms), and deterivores which enjoy a diet enriched by forest litter and terrestrial insects washed into the stream. (Note: See appendix for a gallery and life history of many species referenced). The deterivores range from bacteria, to amphipods (crustacea) to decapod omnivore crustaceans (crayfish in largest percentage), to omnivourous fishes such as stonerollers-(central stoneroller, Campostoma pullum and largescale stoneroller as dominant (MRWDP 1998) and Ozark Minnows and shiners-Notropis -. The stonerollers and crayfish also form the next tier as herbivores, along with herbivorous and ominvourous insect larvae ( mayflies, stoneflies, true flies in that order making up the bulk of benthic riffle non-mussel invertebrates for most of the stream from here on (EPRWIA.. ), dragonfly as well here and in the next tier), Daphnia (planktonic-mostly in slower pools), and larval amphibians (tadpoles and newts).{}. Mussels (Mollusca – 53% in the Dry fork as Lampsilis silliquodea see MRWDP 1998) also reside in larger pools and in areas with smaller granular substrates, and are filter feeders of phytoplankton, detritus, and zooplankton. Snails (Gastropda) cover the rocks near seeps and under rocks in sunlit areas. Madtoms, salamanders, a few darters, and Cyprinids, and juvenile sunfish and bass eat the smaller invertebrates.. Green Sunfish (Lepomis Cyanellis), smaller Largemouth Bass, large crayfish, and bullheads form the next tier. The Largemouth Bass is the dominant top fish predator, with 3 or 4 individuals staking out prime ground in larger pools. Terrestrial and swimming birds (blue herons et al.), reptiles (western water snake, cottonmouth), and mammals (raccoons, and otters) are above these including in the past 10 years river otters in larger numbers. See a more regimented form of this web in Figure 2. Continuing, the stream then receives an injection of cold water from a high output spring, and the community shifts dramatically, accelerating in velocity, injecting minerals and some nutrients, and more importantly dropping the temperature. (Note: tail waters have a similar effect on a larger scale, but that case will be covered under effects in a later paragraph). The clear water of the stream now hosts green mats of vegetation (algae, milfoil, and in particular water cress-Nasturium Pflieger 1997) that wave in the current, with bases attached to rocks, with numerous dots of snails, and legions of amhipods and isopods as decoration. The cool waters (56oF on average from most springs year round) and filtered through caves carrying carbonate and nutrients from clays, soil, and guano filtered through the limestone. This cold water environment shifts in composition at the fish and crustacean level, becoming more diverse after the flow from the stream enters the first few riffles and warms with sunlight. In the cooler sections around the spring the stonerollers are replaced by Shiners and Chubs (Bleeding Shiners, Ozark Minnows and Shiners, and numerous other species). Sculpins (Cottidae) are more dominant then darters (orangethroat) near the springs, with few madtoms. sucker also fit in as omnivores (note white suckers typicall outnumber northern hogsuckers in cold water, see diagram ___, the “sucker spectrum”) , and like the stonerollers in the previous paragraph, are trailed by cyprinids as they feed (a positive indirect interaction that will be mentioned later). Salamander larvae replace tadpoles and share the under rock space with sculpins. While Green sunfish remain present, the dominant sunfish position is taken by the colorful Longear Sunfish ( scientific name here) followed in percentage by the Ozark Bass {{}}. Taking a predatory role on both invertebrates and the cyprinids is the introduced Rainbow Trout near the springs. Eating larger invertebrates and cyprinids is also the Brown Trout (Salmo trutta), and Smallmouth bass (MIcropterus Salmoides) which replace the Largemouth Bass. Ottters again are adept at feeding on larger fishes near the springs, as are minks. Lane Springs on the Little Piney, Meremac Springs, Roubidoux Spring, and several major springs on the Current are examples of this stream section type. See figure #2 for a food web diagram, and Table #2 for a percentage comparison for some species. This stage is also similar in composition to the White River Tailwaters, in which the dam acts a highly variable spring (see the section on factors below), and extends the cold water for many miles. In a third stage of the stream, the springs waters are spread out and warmed as the stream leaves the spring sections, increases in order, and forms larger and larger pools separated by riffles, with some pools becoming very long. Gradually this section transitions from cold water, gravel and boulder pool habitats, to slower warmer waters with gravel, sand, log jams and boulders. Oxbows and backwaters also are broken from the main stream, especially in the swifter parts of this section to form warm water mini-habitats, usually with small feeds to the main stream. As the water warms, salmonids and sculpins give way to smallmouth bass and darters, and gastropod concentrations gradually decrease with distance from the springs (see table). Species shifts in crayfish and mussels also occur. Amphidpod and isopod concentrations very swiftly drop away from the cold water source. See Diagram ____ for the food web for this area. In some streams, a spring may again transform the stream back to a cold water system as in the paragraph above, notably the Current River in Missouri which has many cycles between the second and this third stage. Unless the stream joins another waterway, or is impounded, before this stage, the gradient continues to decrease, stream order increases, the stream width increase, the stream may become nearly continuous pool, and the waters warm further in this final stage. The bottom has more and more sand, silt, and clay, with many backwaters, sand bars, and wetlands. This section usually is marked by the significant presence of water water fish species such as the Gizzard Shad, White Crappie, Channel Catfish, and shortnose gar, with higher concentrations of Largemouth and Spotted Bass, transitions from Longear sunfish to Green sunfish, and larger Perch species such as logperch and Walleye. Aquatic vegetation thickens in slack water areas, and turbidity increases as well. On the bottom the Northern Crayfish become the dominant crayfish species, the larger mussels become more common, and gastropod density drops further.
Many factors influence the health and species composition of an Ozark Stream, though among the most prevalent are temperature, nutrient levels, substrate types, and current speed/reliability. One of the largest effects on temperature and current speed and regularity is impoundments, especially those that form cold tailwaters. While beavers and and do alter stream habitat in smaller streams (Spring Creek in Missouri is a good example of one), both slowing current and allowing water to warm, favoring the food web in figure ##, the large impoundments similar to those on the Red River in Arkansas, and in particular those on the White River itself drastically alter habitat and reduce diversity in the colder tail waters. Tailwaters below large dams in the Ozarks are very cold (46oF), rich in nutrients, but during winter can be low in oxygen. Due to power and flood control requirements, the current and water levels vary drastically, even within the same day. Quin, J.W. and Kwak, T. J. 2003, studied the tail water below Beaver Dam in Arkansas, comparing data from thirty years after dam construction to the data from immediately before to four years after impoundment. While the before and immediately after data did not show a massive shift, data from thirty years later in 1997 showed a very different fish community than in previous measurements. Diversity suffered heavily for Daters and Madtoms, whose place in the ecosystem was the occupied by Sculpins. Salmonids stocked in the region, and the barrier to migration were further impacts. Figure ___ and Table ___ illustrate these points. Also, spectra showing likelihood of prevelance form a few key fish competitors is show in figures ____,___,___. The growth rate (and species present) for Crayfish (see Fig 4 in Evans-White, M.A. and Dodds, W.K. (2003) for an example).
Another factor in Ozark Stream community composition is nutrient load, especially over nutrition from sewage and farm runoff. Hydrology protocols in Missouri show that taxa and relative concentrations of Benthic Invertebrates in riffles, especially Ephemeroptera (Mayflies), can be indicators. In a healthy Ozark Stream, Mayflies compose roughly 50% of the benthic invertebrates [loosely EPRWIA 2000] , using the data in this report and the data for the Spring River [SRWIA 2000], two graph sets shown in ____ and ___ show the shift in invertebrate compositon between 1974 and 1985 for the Eleven Point River, and show a comparison between the Spring River and Eleven Point River. The pollution sources for the Eleven Point (among several factors) resulted in a higher Coleoptera (Water Beetles) and Diptera (True Flies-larvae) concentrations and lower Mayfly (Larvae) concentrations in 1974. Both Water Beetles and True Flies (Especially many Horse Flies – a plague to canoeists on these streams in summer!) are listed by Voshell, J.R., Jr., (2002) as very tolerant to stress and silt.
A third factor in community composition and species diversity is turbidity/ substrate type. Many Ozark Species require gravel of specific type and size to successfully spawn and survive. Fishes such as Smallmouth, Longear, Stonerollers and many other Ozark Cyprinids, and Salmonids, require exposed gravel for bedding. Mollusks require substrate of various types (for the many species in the Ozarks) to live in. Gastropods also use substrate of certain types to feed and crawl over. In an examination of Eleven Point River benthic invertebrate data (also used above, [EPRWIA 2000]), a table for River Mile versus Gastropod density we find the relationship shown in figure ____, where density per square foot decrease log-linearly with river mile (note that the other invertebrates were fairly consistant). Springs are interspersed along the length of this river, and this curve does not match the temperature curve. However, gradient decreases, and order increases with river distance in nearly the same fashion. Substrate particle size decreases with slower current or deeper water, due to physics (Ehlinger, T. 2005). Goldstein, R. M. and Meador, M. R. (2004) note this trend also: “..zooplanktivorous and phytoplanktivorous species should increase as one moves downstream…while benthic invertevores should decrease”. The substrate size may be the cause (would require further research to nail down however). Turbidity can also affect feeding preference in Cyprinids, especially those species not adapted to turbid environments (Bonner, T.H. and Wilde, G.R. 2002).
The Ozark stream community offers many areas for further community ecological analysis. One area that could use more study is an examination of the indirect effects of a browsing omnivore on trailing fishes and subsequent productivity. An example is when a northern hogsucker/white sucker/stoneroller school disturbs the bottom while foraging, also disturbing invertebrates and debris for consumption by longears, salmoniods, and cyprinids which follow nearby, also altering the composition and coverage of algae. This phenomena has been noted by Pflieger (Pflieger 1997) in both disturbance, and in consumption, and is illustrated in figure ___. An experiment could be structured in which the stonerollers and suckers are removed then excluded from a section of a stream, with biomass and species compositions measure before the treatment, and at several periods after the treatment. Treatments of stonerollers versus equal biomass of northern hogsuckers, and variations by water temperature, current speed and gravel size could also be attempted. Another area to examine is the effect of bank tree species composition on fish and invertebrate species abundance and composition. Since crayfish, insect larvae, mussels, and fishes depend on terrestrial nutrient input into their diets, does the species composition of trees lining the banks affect their abundance and size, and what about downstream? This could simply be a study of existing banks of first stage low order streams, or could involve a long term (10yrs+) study in which selective logging and planting could be conducted, then further monitoring would occur at regular (annual) intervals.
To summarize and conclude, Ozark Streams offer a vary diverse and rich range of habitats for a wide variety of species. Each personality of a stearm from low order cool, through spring fed cold, to higher order cool, to high order warmer, including the backwaters, offer many niches and relationships for organisms. The streams however are fragile, and many factors such as temperature, turbidity, nutrients, and silt can alter the community in these streams. Community structure in these streams are indicators for environmental health (see Rabeni, C.F. et al. 1997) and while some like the Eleven Point are recovering, many Ozark Streams have a long way to go to restore the richness we owe to our children
References and Additional Reading
Petersen, J.C. et al. (1998) Et al.“Water Quality in the Ozark Plateaus, Arkansas, Kansas, Missouri, and Oklahoma, 1992-95, USGS Circular 1158.”
Pflieger, W. L. (1997), The Fishes of Missouri, Revised Edition, Conservation Commission of the State of Missouri, © 1997. ISBN 1-887247-11-4.
Quin, J.W. and Kwak, T. J. (2003), “Fish Assemblage Changes in an Ozark River after Impoundment: A Long Term Perspective”, Transaction of the American Fisheries Society, 132:110-119, American Fisheries Society © 2003.
Goldstein, R. M. and Meador, M. R. (2004) “Comparison of Fish Species Traits from Small Streams to Large Rivers”, Transaction of the American Fisheries Society, 133:971-983, American Fisheries Society © 2004
Smith, T.A. and Kraft, C.E. (2005) “Stream Fish Assemblages in Relation to Landscape Position and Local Habitat Variables”, Transaction of the American Fisheries Society, 134:( Galley 176-186 Accepted for Publication 27 Aug 2004), American Fisheries Society © 2005
Rosenfield, J. (2003) “Assessing the Habitat Requirements of Stream Fishes: An Overview and Evaluation of Different Approaches”, Transaction of the American Fisheries Society, 132:953-968, American Fisheries Society © 2003.
Evans-White, M.A. and Dodds, W.K. (2003) “Ecosystem significance of crayfishes and stonerollers in a prairie stream: functional differences between co-occurring omnivores”, Journal of the North American Benthological Society, 22(3):423-441, North American Benthological Society © 2003.
Bonner, T.H. and Wilde, G.R. (2002) “Effects of Turbidity on Prey Consumption by Prairie Stream Fishes”, Transaction of the American Fisheries Society, 131:1203-1208, American Fisheries Society © 2002
[SRWIA 2000] Wilkerson, T.F. Jr., et al., Spring River Watershed Inventory and Assessment, Missouri Department of Conservation, March 2000.
[NRWIA ~1998] Schulz, R.G., et al., Niangua River Watershed Inventory and Assessment, Missouri Department of Conservation.
[JFWIA 2001] Wilkerson, T.F. Jr., et al., Jacks Fork Watershed Inventory and Assessment, Missouri Department of Conservation, Apr 2001.
[CRWIA 2003] Wilkerson, T.F. Jr., et al., Current River Watershed Inventory and Assessment, Missouri Department of Conservation, Jan 2003.
[MRWDP 1998] Blane, T.J. el al., Meramec River Watershed Demonstration Project, funded by U.S. Environmental Protection Agency, Missouri Department of Conservation, Nov 1998.
[EPRWIA 2000] Miller, S.M. and Wilkerson, T.F. Jr., et al., Eleven Point River Watershed Inventory and Assessment, Missouri Department of Conservation, March 2000
Rabeni, C.F. et al. (1997), “Development of a Regionally Based Biological Criteria for Streams of Missouri, A report to the Missouri Department of Natural Resources.”, Missouri Department of Natural Resources, November 1997.
Ehlinger, T. (2005) “(Stream) General Physical Properties Homepage”, Fish Ecology and Restoration webpage, University of Wisconsin-Milwaukee, online at: http://www.uwm.edu/~ehlinger/physical.htm
Voshell, J.R., Jr., (2002) A Guide to Common Freshwater Invertebrates of North America, McDonald&Woodward Pub., © 2002, ISBN 0-939923-87-4
Niering, W.A. (1997) The National Audubon Society Nature Guides. Wetlands., Chanticleer Press, © 1985,1997, ISBN 0-394-73147-6
Meyer, B.L. (2004) The Combat-Fishing Guide to Branson’s Lake Tanneycomo, Trafford, © 2004, ISBN 1-4120-2307-6.
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