A 75-Year History of Aquatic Research at UMBS - G. Win Fairchild, 1983
A 75-YEAR HISTORY OF AQUATIC RESEARCH AT THE UNIVERSITY OF MICHIGAN BIOLOGICAL STATION
G. Win Fairchild
A lecture given at the Station's Diamond (75th) Jubilee - 1983
Faculty, students, and independent investigators at the Biological Station have, since its founding in 1909, been concerned with a broad range of aquatic research, largely reflecting the diversity of habitats and organisms available for study. For example, a large variety of lake types are in close proximity of the Station and are visited regularly by a number of classes. Local streams are similarly abundant. The entire drainage of Carp Creek lies on Station land, and the Maple River, that transports water from the west end of Douglas Lake to Burt Lake, is also used frequently by classes and researchers. Most published work at the Station has been directed, however, toward understanding Douglas Lake and its surrounding wetlands, and it is that body of research l would like to review. This review will consist of three parts. First, l would like to summarize the evidence for vegetational successsion in local wetlands. Second, I will give an overview of major areas of research on Douglas Lake, emphasizing the evidence for long term changes in its trophic status. And finally, l will direct a few concluding remarks toward the present status and future possibilities of aquatic research at the Station.
In preparing this presentation I have attempted to summarize a wide range of information, much of it outside my own areas of research. The assistance of a number of people who kindly provided slides and information is gratefully acknowledged. I wish in particular to mention Dr. N. Andresen, Dr. D. Chandler, Dr. J.E. Gannon, Dr. R. Glover, Dr. N. Miller, Dr. C. Schwintzer, and Dr. C.L. Smith.
EVIDENCE FOR VEGETATIONAL SUCCESSION IN LOCAL WETLANDS
A major concern of early investigators was the vegetational mapping and classification of bogs and fens near the Station (Sigler and Woolett 1926, Goe etal. 1927, Dean and Coburn 1927, Jewell and Brown 1929, Gates 1942, Bevis etal. 1960). More recently, many of these early studies have been reexamined and complemented with measurements of water chemistry and plankton composition (Schwintzer 1978a,1978b, 1979, 1981, Plafkin etal. 1980, Henebry et al. 1981, Schwintzer and Tomberlin 1982).
One major effect of this work has been an adjustment in our thinking concerning the rates of ecological succession in wetland communities. Prevalent theory has viewed vegetational succession in wetlands as a gradual species replacement process, in which early colonizing species accumulate organic matter and otherwise modify their habitat, thus promoting the establishment of later taxa. The wetland is eventually transformed in this manner to an upland climax community.
Schwintzer's work with Bryant's Bog (Schwintzer and Williams 1974, Schwintzer 1978) clearly disputes this theory. Drawing from earlier work (Potzger 1932, Coburn etal. 1933), she has put together a cogent picture of very slow directional change, reversed frequently by high water levels and the consequent destruction of encroaching woody vegetation (e.g., Nemopanthus, llex, Larix, Picea) such as occurred in the early 1970s.
Sanger and Gannon (1979), who similarly drew upon earlier studies of Smith's Fen (Woolett et. al. 1925, Johns 1966), also found that vegetational change had occurred over time. Floral changes were again associated, not with a gradual species replacement process, but with periodic disturbances. A major fire in 1916 grounded the then floating Sphagnum mat, permitting the establishment of willows. The abandonment of a local farm precipitated the decline in the late 1930s of the large stands of Typha that once existed there. Most notably, fluctuating water levels have caused the alternating advance and retreat of stands of Carex lasiocarpa stands that now surround the open water. Vegetational changes in Smith's Fen thus support Schwintzer's contention that our wetlands are going to be around far longer than was once thought, and that changes which do occur are more typically cyclical and are the result of external (allogenic) forces than being unidirectional and biotic (autogenic) in nature. The addition in 1983 of a new course in the Ecology of Peatlands provides much promise for continued research in this area.
THE LIMNOLOGY AND BIOTA OF DOUGLAS LAKE - GEOLOGIC HISTORY AND PHYSICOCHEMICAL FEATURES
Douglas Lake is a moderately large lake, with a surface area of 15.2 km2, a maximum length of 6.1 km, and a maximum depth of 28 m. The lake is unusual in having 7 distinct depressions, separated by extensive shoals. Scott (1921), in his book The Inland Lakes of Michigan concluded that these depressions were of glacial origin. A large irregular block of ice or perhaps a cluster of ice blocks were presumably separated from a retreating tongue of the last continental glacier. The ice blocks were buried under glacial debris, as evidenced by the coarse sand that surrounds Douglas Lake today, and when they eventually melted, left "kettle"-like depressions in their stead. Subsequent variations in water supplied by the glacier were associated with changes in the size and shape of Douglas Lake. Two high water stages are particularly distinguishable from the land forms which surround the lake. The first sediments deposited in the various depressions, primarily a pink clay of low organic content (Wilson 1945), reflect cold water, oligotrophic conditions characteristic of the period when Douglas Lake was part of glacial Lake Algonquin. More recently, what was once a deep lake of low productivity has become a much shallower, moderately eutrophic lake as shown by the black, highly organic sediments of more recent origin. Stoermer (1977), in work based upon diatom analyses of Wilson's earlier core samples, has suggested that the lake has in fact been stably eutrophic for as much as 8000 years.
Sediment accumulation in the depressions of Douglas Lake is influenced both by the settling of planktonic organisms from the water column, and by the influx of materials from nearshore areas. A number of studies have demonstrated the importance of wind driven currents in sorting and transporting sediments. Major currents (Gannon and Fee 1970) typically originate from the northwest end of the lake. Under such winds, this water passes over Big Shoal, entering South Fishtail Bay and forming a large clockwise eddy that leaves the bay through a deep channel just to the east of Grapevine Point (Gannon and Brubaker 1969). Surface waters entering North Fishtail Bay (Tallman 1975) leave the bay via a deep channel just west of East Point. These currents can develop considerable erosional force, as shown by the boulder fields with their streamlike biota located in particularly wave-swept portions of the lake (e.g., Grapevine Point). These currents also have contributed to the formation of recurved spits and their eventual enclosure as beach pools along the shore. This process of beach pool formation has been especially well documented at Sedge Point by Gates (1948) and by subsequent student projects.
The hard water of Douglas Lake reflects the strong influence of a large, calcareous watershed. Chemical features of the well mixed surface waters of the epilimnion, that extends to a depth of approximately 10 m, have been shown to be similar throughout the lake. Waters of the hypolimnion are in contrast to this and are isolated in the 7 depressions of the lake and exhibit unique features according to basin location and morphometry. Early papers concerning this "depression individuality" (Welch 1927, 1944; Welch and Eggleton 1932,1935) have together summarized 26 summers of data for the lake (between 1911 and 1943) and provided a strong conceptual base for later ecological studies.
Only more recently have detailed nutrient data been available for the lake, made possible by the construction of Stockard Laboratory and the acquisition of equipment for our present chem lab. The analysis of the nutrient limitation to algal growth in Douglas Lake was begun by C. Schelske and E. Stoermer using phytoplankton during the early 1970s and, more recently, has been clarified using periphyton by Fairchild and Lowe (1983).
The large majority of papers on Douglas Lake have addressed taxonomic and ecological questions concerning its biota. The few comments l will make serve only to point to the extensive information available for particular groups.
Eggleton (1952) has estimated that 76% of the lake's surface area is underlain by "littoral" sediments less than 9 m in depth. Much of the work on benthic invertebrates associated with the sediments has involved the littoral zone (Cobb 1915, Smith 1916, Eggleton 1931, Moore 1939, Moffett 1943, Hoffman 1940, Neel 1948, Berg 1950, Cole 1953, Lyman 1956, Cort etal. 1960, Clampitt 1970, 1972, 1973,1975), revealing both the high species diversity of these shoal and nearshore communities and the importance of water movements to their distributional ecology. Studies of benthic invertebrates of deeper water in the 7 depressions (Eggleton 1931,1934, Roth 1967) have described much simpler communities, adapted to the cold, oxygen poor water and flocculent sediments of the profundal zone.
Distributional studies of aquatic vascular plants in the lake (Haynes and Hellquist 1978, Gates 1948, Bromley 1967, Williams 1970, J.A. Weber 1972) have emphasized adaptations for growth and dispersal as a function of their physicochemical environments. Algal communities attached to these plants have been examined by Young (1945) and Fairchild and Lowe (1983). In contrast to the extensive work available for benthic invertebrates and plants, studies of the plankton have been few. Papers by Tucker (1957) and Saunders etal. (1962) have addressed the growth and diversity of the phytoplankton, while Campbell (1941) and Fuller et al. (1977) have examined the community composition and population dynamics of rotifers in the lake. Reighard's (1915) early reconnaissance of the fishes of Douglas Lake has received little subsequent comprehensive study. Papers by Weller (1938) and Rodeheffer (1939, 1941, 1945, 1946) have addressed the behavior and distribution of selected species. A large volume of literature exists in addition concerning the fungal and animal parasites of Douglas Lake. These and other references may be located by those interested from the Station's bibliography.
EVIDENCE FOR TROPHIC CHANGE IN DOUGLAS LAKE
Lakes, like wetlands, undergo a form of geological succession over time. Basins gradually fill with sediments, and productivity typically increases. The process is commonly termed eutrophication. Rates of such change are typically slow and usually difficult to detect. Human disturbances of a lake's watershed can, by adding critical nutrients to the lake, also produce changes in productivity. Such "cultural" eutrophication is often perceived over relatively short periods of time. With the availability of limnological information for Douglas Lake over much of this century, it is not surprising that aquatic researchers here have at times addressed this question of trophic change. Three such studies are summarized here.
Sediment Coring as Evidence of Watershed Disturbance
When the Biological Station was first founded in 1909, the surrounding land had been dramatically altered through lumbering, which apparently occurred principally during winter 1879-1880, and subsequent fires which lasted until 1920. As Paul Welch suggested 25 years ago, it was thus logical for early research to turn to Douglas Lake as an environment apparently not affected by this devastation. The analysis of diatoms in a 176 cm sediment core taken from South Fishtail Bay (Andresen 1976), however, suggests that changes in lake water quality did in fact occur during the logging era, as evidenced by the decreased species diversity of the diatom community and by the increased abundance of warm water, eutrophic indicator species, especially Melosira granulata. More recent sediments showed a subsequent stabilization of the diatom community. Andresen interpreted the changes as being the result of increased nutrient runoff from the land owing primarily to the remineralization of bound nutrients by fires which swept the area. Increased nutrient retention apparently ensued within the watershed during secondary terrestrial succession. Slight increases in trophic status since the 1940s, when rapid recreational (cottage) development occurred at the west end of the lake, are also suggested by an increase in eurytopic species in the uppermost 12-16 cm of the sediments.
The Hypolimnetic Oxygen Deficit (1911 to 1964)
Oxygen content in the bottom waters, or hypolimnion, of a lake during mid summer is dependent upon the amounts of organic material settling from above, and upon the degradation of these materials, largely by bacterial respiration. Accordingly, the greater the production of organic matter, the greater the sedimentation rate and consequent oxygen consumption as decomposition proceeds. The rates of hypolimnetic oxygen depletion (HOD) can thus be utilized as an index of lake productivity. For example, Lind (1978) hypothesized that the basins close to the cottage development at the west end of Douglas Lake should experience increased algal growth and consequently greater hypolimnetic oxygen depletion. His comparison of Fairy Island, Grapevine Point, and South Fishtail Bay depressions revealed an unexpectedly high oxygen depletion rate in South Fishtail Bay, which he attributed to its protection from wind action and its cul-de-sac location within the lake. Bazin and Saunders (1971) examined the HOD for South Fishtail Bay beginning with data from Welch in 1911 and ending with unpublished data of Chandler and Saunders in 1964. Apparent from their study is considerable year-to-year variation in the HOD estimates, but a significant (p<.05) trend toward an increasing rate of oxygen depletion during the 54 year time interval. The authors interpreted this trend as evidence of slow eutrophication in the lake. Available information for net primary production that shows a 2-3 fold increase from 1959 (Saunders etal. 1962) to 1970-1971 (Lind 1978) appears to support this view. Likewise, the comparison of total rotifer densities in the lake in 1938 (Campbell 1941) with densities in South Fishtail Bay three decades later (Fuller etal. 1977) has suggested approximately 4 fold increases in herbivorous zooplankton abundance, again supporting the contention of increases in lake productivity. In contrast, available nutrient and other chemical data during the past 75 years (Pratt and Cairns 1983) provide no evidence of significant change in the lake trophic state.
Protozoan Colonization Patterns (1969 to 1982)
Artificial substrates, when placed in a lake, are gradually colonized by an assortment of protozoan species that immigrate from already existing surfaces in the lake. Cairns et al. ( 1979) have shown that both the rate of increase in numbers of species (G) and the equilibrium species number that can exist stably on the new substrates (Seq) are enhanced in response to eutrophication. Pratt and Cairns (1983) have examined colonization patterns for protozoans in Douglas Lake from 1969 to 1982. No consistent trends in either G or Seq were found, and the authors interpreted their results as indicating trophic stability in the lake during this time interval.
Evidence addressing the question of trophic change in Douglas Lake is thus incomplete and somewhat contradictory. Cultural eutrophication in the lake was apparently most pronounced during the logging era. Gradual changes in productivity may also have occurred during the development of the west end of the lake, but no published evidence exists for changes in water quality during the recent past. Much remains to be learned.
Facilities such as the University of Michigan Biological Station are perhaps uniquely suited for the development of large quantities of research data, obtained over many years and by many authors, all directly or indirectly aimed at understanding the intricacies of a single ecological system. Douglas Lake has historically been such a habitat, and numerous authors have examined the lake or its biota. This is in one sense impressive. Many of the papers briefly mentioned here have been influential in expanding the perimeters of our understanding in limnology and aquatic ecology. Considerable satisfaction can likewise be derived in the slow accumulation of knowledge by single individuals associated with the Station for long periods of time. A synopsis of aquatic research during the past 75 years is at the same time frustrating, however, in its revelation of a myriad of comparatively isolated research efforts, designed along conceptual lines to which the lake as an ecological entity has been incidental. One is struck with the analogy of a large puzzle of many individual pieces, at a stage in its completion where relatively few of the pieces have been joined to form a discernible picture. Studies of vegetational succession in Bryant's Bog and Smith's Fen, examination of the physical processes governing the distribution of sediments and benthic organisms of Douglas Lake, the examination of physicochemical and biological data to infer "depression individuality" and lake trophic state represent unusual instances where the information of early studies has been integrated with later research.
The Station staff can help to facilitate the integration of research on the lake and adjacent water bodies. First, the Station is in the process of collating published information as well as student papers in a form cross indexed according to topic and thus easily accessible to future researchers. The presence of a permanent staff member interested in aquatics and available as a source of ideas and information was begun in 1972 with the arrival of Dr. John Gannon. Dr. Gannon's presence was critical to the gathering of year round information on Douglas Lake and to the organizing of a comprehensive research effort on water quality in this region. Dr. Gannon remained at the Station for 6 years and was succeeded by Dr. Ned Grossnickle between 1979 and 1982, but no aquatics staff member has been in residence at the Station since that time. The accumulation of knowledge is a process that feeds upon itself. As the available data base and research facilities of the Station become increasingly recognized, the future of aquatic research here cannot help but be bright.
All the references prior to 1959 are contained in the Station bibliography published with the Semicentennial Proceedings in 1959. All references of the last 25 years are to be found in the Station bibliography contained in this volume.