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Plant and Wildlife Information Fish Surveys conducted in 1938 (Brown and Funk 1945) and 1977 (Yant and Humphries 1978) were accomplished by seining, so lampreys and redhorses are probably under-represented due to the selectivity of the gear. The 1954 (Cooper 1954) and 1992 (Kosek 1993) collections were by direct-current electroshocking, which is less selective. The distributions of various species range from small isolated pockets to basin-wide. Many native species are still present and abundant; a number have declined severely and are now rare; others have increased in abundance. Five species are considered threatened (silver shiner, redside dace, southern redbelly dace, eastern sand darter, and sauger) and one is considered endangered (northern madtom). Two species have been extirpated from the drainage, channel darter and river darter. Twelve non-indigenous fish species have been introduced into the watershed. These include unintended and intentional introductions, and migrations. All but brook trout are still present. Brook trout, stocked from 1900 to 1920, did not establish persistent, reproducing populations. The distribution ranges of these species, with the exception of goldfish and common carp, has remained limited. In 1977 fish communities in the upper river and the major tributaries were diverse and indicated relatively healthy systems (Yant and Humphries 1978). The species present reflected the persistence of fairly cool, clear water and some gravelly substrates. However, two major fish groups had declined (see also Trautman and Gartman 1974; Smith et al. 1981). Many species dependent on clear, heavily-vegetated water had either disappeared or decreased in number . These species were often associated with natural lake outlets that have been replaced in many instances with lake-level control structures. Species dependent on clean gravel substrates had similarly disappeared or declined sharply. Many of these required gravel for spawning and a flow of clean water to their protected eggs. Species preferring or tolerating silt and sand substrates became more abundant during this time. One reason that these species are able to cope with silt is their spawning strategies. For example the male johnny darter picks a nesting site under appropriate substrate and then provides parental care to the eggs, fanning them with his pectoral fins to maintain a flow of oxygen and keeping them free of silt. In a 1992 survey by SWQD (Anon 1991c), Kosek (1993) scored the fish community as good for 13 of the 15 sites on the mainstem. A good rating indicates that the community is slightly impaired, less optimal than would be expected due to the loss of intolerant species (Anon 1991c). The group most under-represented in the river were insectivores (chubs, minnows, and shiners). Species of redhorse suckers that are intolerant of chemical and habitat degradation, were also sparse. The density of individuals in all fishery groups was low compared to expected densities. Of the tributaries, Mill Creek shows the most extreme example of changes. Between 1938 and 1977 there was a decline of 15 species (8 lost), including 9 requiring vegetation and 5 requiring gravel. Concurrently, 6 species increased in abundance. Of these, 4 prefer silt and sand substrates (Yant and Humphries 1978). In 1992, Kosek (1993) found that little had changed. Insectivores and piscivores were under-represented as were sunfish species. The latter are sensitive to degradation of pool habitat and loss of in-stream cover (Karr et al. 1986). As described above, the eight impoundments from Ann Arbor to Flat Rock were treated with rotenone in 1972-74 to remove high densities of common carp. This was followed by stocking an assortment of gamefish species, as soon as waters were non-toxic (Laarman 1979). Present fish communities predominately include a mixture of common carp, sunfishes, and bass that are adapted to the eutrophic condition of these reservoirs. All the reservoirs contain populations of walleye that intermittently reproduce in the upstream riverine section (J. Schneider, FD, personal communication; FD records). Limited numbers of several potamodromous species now use the river below Flat Rock Dam, including chinook salmon and steelhead (both stocked), gizzard shad, white sucker, channel catfish, white perch, white bass, smallmouth bass, walleye, and freshwater drum (creel census at Flat Rock 1989-1993, FD, MDNR). Aquatic Invertebrates (except mussels) There have been no comprehensive invertebrate studies on the river except van der Schalie's (1938) work on mussels and the identification of some species of special concern . Invertebrates, which are less mobile than other aquatic species, often provide more direct indications of habitat problems that are affecting fish and other aquatic life. In 1992, a SWQD survey of macroinvertebrates was conducted (Anon 1991c; Kosek 1993). Fifteen locations on the mainstem were surveyed. All sites, except the one furthest upstream, were rated as slightly to moderately impaired. Ten of the downstream sites were less than optimal due to some loss of species that are intolerant to degradation. Many times there was a marked reduction in the number of mayflies and caddisflies. Stonefly abundances were more variable. Four sites, three in Oakland County and one just below Belleville Lake, were more degraded with loss of all intolerant species and reduced numbers of mayflies, caddisflies, and stoneflies. Sites were also evaluated on some of the tributaries. Hayes Creek (Oakland County), Davis Creek, Ore Creek, Portage Creek, Honey Creek, and the lowest sample site on Mill Creek were all rated as good (some loss of intolerant species). The two uppermost sites on Mill Creek and the one site on Boyden Creek (also known as Loch Alpine Creek) were ranked fair (loss of intolerant forms and reduced abundance of mayflies, stoneflies, and caddisflies). A more complete inventory of the macroinvertebrate fauna of the Huron River watershed is recommended. Mussels An extensive survey of the mussels in the Huron River system was completed in 1931-33 (van der Schalie 1938). This work includes species distribution maps. The diversity and abundance of various mussel species indicated that characteristic ecological assemblages existed. Fourteen habitat types are listed, each with a distinct fauna. These included river lakes, land-locked lakes, impounded waters, creeks, and small, medium, and large river zones. In general, the number of species increased with stream size; brooks and creeks had 2 to 9 species, small rivers had about 14 species, and large rivers had about 17 species. At the river mouth, 4 species from Lake Erie were found. This survey is probably representative of the original fauna above Ann Arbor. Mussel distributions are excellent habitat indicators as they are sessile and reflect both their own tolerances of local environmental conditions (including pollution and siltation) and the tolerances of their host fishes. By the 1930s, from Ann Arbor to Flat Rock, mussel communities were negatively affected by dams and pollution. Downstream of Flat Rock they were negatively affected by variable stream flows, sewage, other pollutants, and clamming (the harvest of mussels for their shells to make pearl buttons); in many areas of this section there were no mussels (van der Schalie 1958; Jessup 1993). Significant changes in the mussel community occurred during the Second World War (van der Schalie 1958). The industrial effort that went on in southeast Michigan was geared towards production of needed war materials, and little or no thought was given to the negative affects of production on the environment. One example was a laundry at Dexter that cleaned rags used to wipe machinery in plants in Detroit. The sewage disposal system of the town could not handle the amount of waste water produced each day, so a great deal of untreated effluent went into the river. The result was that this plant, operating only during the war (approximately 2 years), nearly wiped out all mussels and aquatic operculates [certain snail species] in the Huron River below Dexter (van der Schalie 1958). In 1969, when repairs were being made to Argo Dam in Ann Arbor and consequently the water in Argo impoundment had been lowered, van der Schalie sampled some river shoals below Barton Dam in an attempt to determine the original fauna of the river at this point.. During a 1930s survey, 13 species were found in this vicinity, alive and in abundant numbers (van der Schalie 1938). During the 1969 survey, 10 species were taken of which only six species were alive. Of these six, only two species, the pink wartyback (also known as the purple wartyback) and the papershell were present in any appreciable number (van der Schalie 1970). Van der Schalie noted the lack of young specimens and concluded that the ecological changes from a flowing river to an impoundment no longer allowed for the successful completion of the life cycle of riverine species. The Michigan Natural Features Inventory lists four mussel species as "of concern" (Table 11): wavy-rayed lamp (special concern/proposed threatened); snuffbox (threatened/proposed extinct); purple wartyback (special concern); and northern riffleshell (extinct). The first three were either abundant or common in certain habitats in 1938. A comprehensive survey is needed to determine present mussel populations. Amphibians and Reptiles Thirty-four species of amphibians and reptiles that require the river or its associated wetlands (riparian, upland, wooded, seasonal) in some or all of their life history stages, have been found in the watershed . Two are questionable records and are being re-examined. The report of the mink frog is based on four juvenile specimens that may have been misidentified. The record of the wood turtle is based on only one specimen recorded early in the century. The Michigan Natural Features Inventory lists four species as "of concern" – three of which are species that require wetland habitat, and a fifth species is considered threatened: Blanchard's cricket frog (special concern), spotted turtle (special concern), massasauga (special concern), eastern fox snake (threatened), and smallmouth salamander . Mammals The river corridor is a critical habitat to many mammalian and bird species. It provides a refuge, a source of water, and in many instances the last undisturbed living space. The presence of this forested corridor is the major reason some animals in the watershed have been able to withstand the intensive development of the landscape (both agricultural and urban) by man. Mammals in the watershed include raccoon, mink, muskrat, beaver, and otter (R. Anderson, Wildlife Division, MDNR, personal communication). The first three species are present in moderate to very abundant populations, primarily in the river corridor. Low numbers of beaver, found predominately in the headwater areas, are increasing in numbers. Otter are rare; they have possibly been extirpated due to over-harvest. Wildlife Division has plans underway to re-introduce this species in this drainage (E. Kafcas, Wildlife Division, MDNR, personal communication). A species of special concern is the least shrew . Birds This watershed is an important area for a variety of waterfowl. As part of the Mississippi Valley Flyway, it is used by Canada geese and many species of ducks (T. Payne, Wildlife Division, MDNR, personal communication). It is also used as a stopover for migrating bald eagles, peregrine falcons, ospreys, and sandhill cranes. Significant rookeries for Great blue heron exist within the watershed. As mentioned above, the presence of the forested river corridor and seasonally flooded uplands are critical for the maintenance of these populations and without it, many of these species would no longer be in this locality. Equally as critical is the river itself, which is a food source for many of these species. Pest Species Pest species are defined as those aquatic species that have been introduced, either accidentally or intentionally, and pose a significant threat to native species or their habitat. Most species do not pose any threat unless they are present in high densities. High densities of fish pest species are not known to be present in the Huron River, its impoundments, or natural lakes. Sea lamprey have not invaded the lower Huron River (Morman 1979) as spawning substrate is not readily available below Flat Rock Dam (D. Lavis, USFW, personal communication). No upstream migration could occur beyond Flat Rock, as two dams block the river at this point. Pest species of mollusks such as zebra mussels, and crustaceans such as the European spiny water flea, have invaded Lake Erie (Mills et al. 1993), but no colonization in the Huron River has been reported at present. Rusty crayfish have been identified being sold as bait in the Chelsea area, Washtenaw County (P. Seelbach, FD, MDNR, personal communication) and at Flat Rock, Wayne County (G. Towns, FD, MDNR, personal communication). The Asian clam was detected in Whitmore Lake, Washtenaw-Livingston county line. Zebra mussel veligers were first detected in Belleville Lake, Wayne County in 1993; no adults were reported (Marangelo and Johnson 1993). In 1994 the detection program for zebra mussels was expanded (Marangelo 1994). Veligers were again detected in Belleville Lake and in Kent Lake, Oakland County. As well, three incidental detections of adult populations were confirmed in Barton Pond, Washtenaw County, and in Portage and Whitmore lakes on the Washtenaw- Livingston county line. Secondary downstream dispersal from established inland populations is becoming an important dispersal method along with transient boating activity. Marangelo (1994) believes that secondary downstream dispersal is responsible for the population in Barton Pond, the origins being the Portage Lake population. If this is correct, all seven impoundments down to Flat Rock would become infested. The known plants species that are considered pests are purple loosestrife, Eurasian milfoil, and curly leaf pondweed. Purple loosestrife, a perennial emergent wetland plant native to Europe and Asia is well established in marshy areas at the mouth of the river, around lake perimeters, and in wetlands throughout the watershed. Unfortunately one of the prime methods of dispersal has been humans, who often move plants into their gardens or waterfronts, attracted by its purple flowers. Dispersal of seeds can be by wind, flowing water, and animals including humans (Skinner et al 1994). This species is particularly dangerous as it can out-compete native wetland plants and take over their habitat. It has no appreciable wildlife food or cover value and replaces species that are important (Eggers and Reed 1987). Eurasian milfoil, a submerged perennial herb, is present in quiet waters of lakes, rivers, and deep marshes. It is dispersed by fragmentation of plant parts and is in the watershed in densities ranging from scarce to nuisance amounts. This species can become a nuisance by forming dense mats that interfere with swimming, fishing, and boating. Curly leaf pondweed, another submergent perennial herb, is also present in scarce to nuisance densities in marshes and lakes. Its methods of dispersal are by plant fragments and turions. It too may form dense mats of near-surface vegetation that interfere with boating, swimming, and fishing activities (Eggers and Reed 1987). The one terrestrial species that can negatively affect the watershed is the gypsy moth. Damage from this insect is most severe in forested areas that have been under previous stresses (W. Hoppe, Forestry Division, MDNR, personal communication). To date the gypsy moth has only been found in isolated pockets within the watershed. This information was taken fom a report done by the DNR. The PDF version of the report can be downloaded here. |
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