Geology topics
Don W. Schloesser
Publications and source records attributed to Don W. Schloesser.
Distribution and abundance of freshwater polychaetes, Manayunkia speciosa (Polychaeta), in the Great Lakes with a 70-year case history for western Lake Erie
Manayunkia speciosa has been a taxonomic curiosity for 150 years with little interest until 1977 when it was identified as an intermediate host of a fish parasite (Ceratomyxa shasta) responsible for fish mortalities (e.g., chinook salmon). Manayunkia was first reported in the Great Lakes in 1929. Since its discovery, the taxon has been reported in 50% (20 of 40 studies) of benthos studies published between 1960 and 2007. When found, Manayunkia comprised < 1% of benthos in 70% of examined studies. In one extensive study, Manayunkia occurred in only 26% of 378 sampled events (1991–2009). The taxon was found at higher densities in one area of Lake Erie (mean = 3658/m 2 ) and Georgian Bay (1790/m 2 ) than in five other areas (mean = 60 to 553/m 2 ) of the lakes. A 70-year history of Manayunkia in western Lake Erie indicates it was not found in 1930, was most abundant in 1961 (mean = 8039, maximum = 67,748/m 2 ), and decreased in successive periods of 1982 (3529, 49,639/m 2 ), 1993 (1876, 25,332/m 2 ), and 2003 (79, 2583/m 2 ). It occurred at 48% of stations in 1961, 58% in 1982, 52% in 1993, and 6% of stations in 2003. In all years, Manayunkia was distributed primarily near the mouth of the Detroit River. Causes for declines in distribution and abundance are unknown, but may be related to pollution-abatement programs that began in the 1970s, and invasion of dreissenid mussels in the late-1980s which contributed to de-eutrophication of western Lake Erie. At present, importance of the long-term decline of Manayunkia in Lake Erie is unknown.
Early responses to zebra mussels in the Great Lakes: a journey from information vacuum to policy and regulation
Invasive species such as zebra mussels pose a threat to the economies and environments of coastal and fresh-water habitats around the world. Consequently, it is important that government policies and programs be adequate to protect these waters from invaders. This chapter documents key events that took place in the early years (1988-1991) of zebra mussel colonization of the Laurentian Great Lakes and evaluates government responses (policies and programs) to this disruptive, invasive, freshwater species.
Bibliography of Dreissena polymorpha (zebra mussels) and Dreissena rostriformis Bugensis (QUAGGA mussels): 1989 to 2011
Dreissenid mussels invaded and colonized waters of the Laurentian Great Lakes during the late 1980s. Their colonization and resulting impact have been characterized as one of the most important ecological changes in freshwater systems in North America. The need for information on dreissenid mussels has grown during the past 2 decades, which has prompted the compilation of this bibliography. Two previous bibliographies of dreissenid mussels indicate average publication rates were 6 publications/year between 1771 and 1964 (1,180 in 194 y) and 30 publications/year between 1964 and 1993 (885 in 30 y). In the current bibliography, the average rate of publication doubled during the past 23 y (1989 to 2011) to 66 publications/year based on a total of 1,502 publications. These rates may be biased by increased numbers of researchers and journals over time but, at a minimum, these rates indicate continued interest and concern by humans about the impact of dreissenid mussels on water availability and the expanding range of dreissenids throughout the world. The current bibliography has a 94% efficiency rate for subject and 100% efficiency for title search criteria when compared with references in published studies of dreissenid mussels in 2011. In addition to publications, we included 206 student theses and 225 chapters in 26 books including 6 books devoted solely to dreissenid mussels. A vast majority of student theses were about dreissenid mussels in North America, especially in the Laurentian Great Lakes. The 6 books devoted to dreissenid mussels contained a variety of chapters that described biology, impact, control, and ecology of dreissenid mussels in both Europe (published in 1992 and 2010) and North America (1993, 1994, 1997, and 2000). In addition, there is a 7th book devoted solely to dreissenid mussels that is near completion.
Extirpation of freshwater mussels (Bivalvia: Unionidae) following the invasion of dreissenid mussels in an interconnecting river of the Laurentian Great Lakes
Previous (1992–1994) surveys for native freshwater mussels (Unionidae) along main channels of the Detroit River showed that unionids had been extirpated from all but four sites in the upper reaches of the river due to impacts of dreissenid mussels ( Dreissena polymorpha and D. bugensis ). These four sites were surveyed again in 1998 using the same sampling method (timed-random searches) to determine if they may serve as “refugia” where unionids and dreissenids co-exist. Two additional sites were sampled using additional methods (excavated-quadrat and line-transect searches) for comparison with unpublished data collected in 1987 and 1990. A total of four individuals of four species ( Actinonaias ligamentina , Cyclonaias tuberculata , Lasmigona complanata and Pleurobema sintoxia ) were found by timed-random searches at four sites in 1998 compared to 720 individuals of 24 species in 1992 and 39 individuals of 13 species in 1994. Excavated-quadrat and line-transect searches at the two additional sites yielded only one live specimen of Ptychobranchus fasciolaris compared to 288 individuals of 18 species in 1987 and 1990. Results of this study suggest that remaining densities of unionids in channels of the Detroit River are too low to support viable reproducing populations of any species. Therefore, we conclude that unionids have been extirpated from main channels of the Detroit River due to dreissenid infestation. As the Detroit River was one of the first water bodies in North America to be invaded by dreissenids, it is likely that unionids will also be extirpated from many other rivers and lakes across eastern North America over the next few decades. Resource agencies should be encouraged to implement active management programs to protect remaining unionid populations from zebra mussels.
Recruitment of Hexagenia mayfly nymphs in western Lake Erie linked to environmental variability
After a 40-year absence caused by pollution and eutrophication, burrowing mayflies (Hexagenia spp.) recolonized western Lake Erie in the mid 1990s as water quality improved. Mayflies are an important food resource for the economically valuable yellow perch fishery and are considered to be major indicator species of the ecological condition of the lake. Since their reappearance, however, mayfly populations have suffered occasional unexplained recruitment failures. In 2002, a failure of fall recruitment followed an unusually warm summer in which western Lake Erie became temporarily stratified, resulting in low dissolved oxygen levels near the lake floor. In the present study, we examined a possible link between Hexagenia recruitment and periods of intermittent stratification for the years 1997-2002. A simple model was developed using surface temperature, wind speed, and water column data from 2003 to predict stratification. The model was then used to detect episodes of stratification in past years for which water column data are unavailable. Low or undetectable mayfly recruitment occurred in 1997 and 2002, years in which there was frequent or extended stratification between June and September. Highest mayfly reproduction in 2000 corresponded to the fewest stratified periods. These results suggest that even relatively brief periods of stratification can result in loss of larval mayfly recruitment, probably through the effects of hypoxia. A trend toward increasing frequency of hot summers in the Great Lakes region could result in recurrent loss of mayfly larvae in western Lake Erie and other shallow areas in the Great Lakes.
Potential oxygen demand of sediments from Lake Erie
Dreissenid mussels ( Dreissena polymorpha and D. bugensis ) biodeposit large quantities of filtered materials (i.e., feces and pseudofeces) directly on bottom substrates. These biodeposits have the potential to increase oxygen demand in sediments and overlying waters and thus contribute to hypolimnetic anoxia in Lake Erie. We hypothesized that higher potential oxygen demand of sediments would occur in areas near shore than in offshore hypolimnetic waters as a result of biodeposits carried by currents from littoral water where mussels, available foods, and biodeposits may be most abundant. To address this hypothesis, we measured potential oxygen demand (mg O2/L/120 h incubation) at six sites near shore and six sites offshore monthly June to September 2002 and August 2003. In addition, we compared, in post priori hypothesis, seven sites with and five sites without dreissenid mussels. Contrary to our hypotheses, potential oxygen demand was not significantly higher in bottles containing nearshore sediments than offshore sediments. Similarly, potential oxygen demand was not significantly higher at sites with dreissenid mussels than at sites without mussels. Data are consistent with pre-dreissenid studies which show oxygen demand and percent ash-free dry weights of sediments were higher offshore than near shore and ash-free dry weight of sediments decreased June to September. Therefore, the present study provides no evidence that dreissenid mussels have contributed directly-via biodeposition-to increased anoxia observed in Lake Erie in the mid to late 1990s.
First finding of the amphipod Echinogammarus ischnus and the mussel Dreissena bugensis in Lake Michigan
The first finding of the amphipod Echinogammarus ischnus and the mussel Dreissena bugensis in Lake Michigan is documented. These two species are widespread and abundant in the lower lakes, but had not yet been reported from Lake Michigan. E. ischnus is generally considered a warmwater form that is typically associated with hard substrates and Dreissena clusters in the nearshore zone. Along the eastern shoreline of Lake Michigan, this species was present at rocky, breakwall habitats along the entire north-south axis of the lake. Although not abundant, this species was also found at soft-bottomed sites as deep as 94 m in the southern basin. The finding of this species in deep offshore waters apparently extends the known habitat range for this species in the Great Lakes, but it is found in deep water areas within its native range (Caspian Sea). D. bugensis was not abundant, but was present in both the southern and northern portions of the lake. Individuals of up to 36 mm in length were collected, indicating that it had probably been present in the lake for 2 or more years. Also presented are depth-defined densities of D. polymorpha at 37 sites in the Straits of Mackinac in 1997, and densities at up to 55 sites in the southern basin in 1992/93 and 1998/99. Mean densities decreased with increased water depth in both regions. Maximum mean density in the Straits in 1997 was 13,700/m 2 (≤ 10 m), and maximum density in the southern basin in 1999 was 2,100/m 2 (≤ 30 m). Mean densities at the ≤ 30-m interval in the southern basin remained relatively unchanged between 1993 and 1999, but increased from 25/m 2 to 1,100/m 2 at the 31 to 50 m interval over the same time period. D. polymorpha was rare at sites > 50 m. The presence of E. ischnus and the expected population expansion of D. bugensis will likely contribute to further foodweb changes in the lake.
Recolonization and possible recovery of burrowing mayflies (Ephemeroptera: Ephemeridae: Hexagenia spp.) in Lake Erie of the Laurentian Great Lakes
Burrowing mayflies of the genus Hexagenia spp. were widely distributed (ca. 80% of sites) and abundant (ca. 160 nymphs/m 2 ) in the western basin of Lake Erie of the Laurentian Great Lakes in 1929–1930, prior to a period of anoxia in the mid 1950s. Nymphs were absent or rare in the basin between 1961 and 1973–1975. In 1979–1991, nymphs were infrequently found (13–46% of sites) in low abundance (3–40 nymphs/m 2 ) near shore (<7.5 km from shore), but were absent or rare offshore (0–7% of sites at 0–1 nymphs/m 2 ). Increased abundance occurred offshore between 1991 (0% of sites) and 1993 (52% of sites at 7/m 2 ). Annual sampling, beginning in 1995, indicates that nymphs increased in both nearshore and offshore waters. By 1997, nymphs were found throughout the lake (88% of sites) at a mean density 40-fold greater (392/m 2 ) than that observed in 1993 (11/m 2 ). In 1998, the distribution of nymphs remained the same as 1997 (88% of sites) but density declined 3-fold (392 to 134/m 2 ). These data indicate that mayflies have recolonized sediments of western Lake Erie and that their abundance may be similar to levels observed before their disappearance in the mid 1950s. However, prior to the mid 1950s, densities were greater in offshore than nearshore waters, but between 1979 and 1998 greater densities occurred near shore than offshore. In addition, there were two areas in the 1990s where low densities consistently occurred. Therefore, recovery of nymphs in western Lake Erie may not have been complete in 1998. At present we do not know the cause for the sudden recolonization of nymphs in large portions of western Lake Erie. Undoubtedly, pollution-abatement programs contributed to improved conditions that would have ultimately led to mayfly recovery in the future. However, the explosive growth of the exotic zebra mussel, Dreissena polymorpha , undoubtedly diverted plankton foods to bottom substrates which could have increased the speed at which Hexagenia spp. nymphs recolonized sediments in western Lake Erie in the 1990s.
Mortality of unionid bivalves (Mollusca) associated with Dreissenid mussels (Dreissena polymorpha and D. bugensis) in Presque Isle Bay, Lake Erie
Two exotic species of dreissenid mussels (Dreissena polymorpha and D. bugensis) began to colonize bottom substrates in Presque Isle Bay, Lake Erie in 1990. By 1991, all native unionid (Unionidae) shells were infested by dreissenids. In 1990 and 1991, about 500 individual unionids of 15 species were collected: in 1992, 246 individuals of 12 species were collected; in 1993, 64 individuals of 6 species; in 1994, three individuals of three species; and in 1995, no unionids were found. In general, infestation indices of unionids were relatively low in 1990 and 1991, increased in 1992, and decreased in 1993. Mortality of unionids associated with infestation in the bay occurred in a shorter period of time (ca. two to three years) than has been documented in other water bodies. Observations in an area of Presque Isle not included in the present study, indicate that a small remnant population of unionids exists in the presence of heavily-colonized substrates by dreissenid mussels. Since other shallow-water areas of Lake Erie support infestation-free unionids in the presence of dreissenid mussels, it is hoped that some unionids will survive in Presque Isle Bay of Lake Erie.
Population models of burrowing mayfly recolonization in western Lake Erie
Burrowing mayflies, Hexagenia spp. ( H. limbata and H. rigida ), began recolonizing western Lake Erie during the 1990s. Survey data for mayfly nymph densities indicated that the population experienced exponential growth between 1991 and 1997. To predict the time to full recovery of the mayfly population, we fitted logistic models, ranging in carrying capacity from 600 to 2000 nymphs/m 2 , to these survey data. Based on the fitted logistic curves, we forecast that the mayfly population in western Lake Erie would achieve full recovery between years 1998 and 2000, depending on the carrying capacity of the western basin. Additionally, we estimated the mortality rate of nymphs in western Lake Erie during 1994 and then applied an age-based matrix model to the mayfly population. The results of the matrix population modeling corroborated the exponential growth model application in that both methods yielded an estimate of the population growth rate, r, in excess of 0.8 yr −1 . This was the first evidence that mayfly populations are capable of recolonizing large aquatic ecosystems at rates comparable with those observed in much smaller lentic ecosystems. Our model predictions should prove valuable to managers of power plant facilities along the western basin in planning for mayfly emergences and to managers of the yellow perch ( Perca flavescens ) fishery in western Lake Erie.
Comparative biology of zebra mussels in Europe and North America: an overview
SYNOPSIS. Since the discovery of the zebra mussel, Dreissena polymorpha , in the Great Lakes in 1988 comparisons have been made with mussel populations in Europe and the former Soviet Union. These comparisons include: Population dynamics, growth and mortality rates, ecological tolerances and requirements, dispersal rates and patterns, and ecological impacts. North American studies, mostly on the zebra mussel and a few on a second introduced species, the quagga mussel, Dreissena bugensis , have revealed some similarities and some differences. To date it appears that North American populations of zebra mussels are similar to European populations in their basic biological characteristics, population growth and mortality rates, and dispersal mechanisms and rates. Relative to European populations differences have been demonstrated for: (1) individual growth rates; (2) life spans; (3) calcium and pH tolerances and requirements; (4) potential distribution limits; and (5) population densities of veligers and adults. In addition, studies on the occurrence of the two dreissenid species in the Great Lakes are showing differences in their modes of life, depth distributions, and growth rates. As both species spread throughout North America, comparisons between species and waterbodies will enhance our ability to more effectively control these troublesome species.
Zebra mussel infestation of unionid bivalves (Unionidae) in North America
In 1989, zebra mussels received national attention in North America when they reached densities exceeding 750,000/m2 in a water withdrawal facility along the shore of western Lake Erie of the Laurentian Great Lakes. Although water withdrawal problems caused by zebra mussels have been of immediate concern, ecological impacts attributed to mussels are likely to be the more important long-term issue for surface waters in North America. To date, the epizoic colonization (i.e., infestation) of unionid bivalve mollusks by zebra mussels has caused the most direct and severe ecological impact. Infestation of and resulting impacts caused by zebra mussels on unionids in the Great Lakes began in 1988. By 1990, mortality of unionids was occurring at some locations; by 1991, extant populations of unionids in western Lake Erie were nearly extirpated; by 1992, unionid populations in the southern half of Lake St. Clair were extirpated; by 1993, unionids in widely separated geographic areas of the Great Lakes and the Mississippi River showed high mortality due to mussel infestation. All infested unionid species in the Great Lakes (23) have become infested and exhibited mortality within two to four years after heavy infestation began. Data indicate that mean zebra mussel densities >5,000–6,000/m 2 and infestation intensities >100-200/unionid in the presence of heavy zebra mussel recruitment results in near total mortality of unionids. At present, all unionid species in rivers, streams, and akes that sympatrically occur with zebra mussels have been infested and, in many locations, negatively impacted by zebra mussels. We do not know the potential consequences of infestation on the 297 unionid species found in North America, but believe zebra mussels pose an immediate threat to the abundance and diversity of unionids.
Distribution and winter survival health of Asian clams, Corbicula fluminea, in the St. Clair River, Michigan
We studied the distribution and winter survival of the Asian clam, Corbicula fluminea, in the St. Clair River from the fall of 1988 to the spring of 1990. Between fall of 1988 and spring of 1989, distribution of Corbicula was extended from 5.5 to 11.5 km downstream from an electric power plant. However, total abundance of clams decreased during the winter. By fall of 1989, Corbicula was found 14.5 km from the power plant, and the mean density of clams was 27 individuals/m 2 . Between fall of 1989 and spring of 1990, distribution was reduced to 7.5 km from the power plant and abundance decreased 97%. During the winter of 1988-1989, we collected clams monthly from one station 2.2 km from the power plant, and we observed that clams survived the harsh winter for two months after the water temperature dropped about 1.5°C below the reported lethal level for Corbicula in midwinter. During the winer of 1989-1990, we held clams at the sediment-water interface in enclosures, and we observed that condition indices (dry body weight; dry shell weight) of clams remained stable (mean = 0.05 ± 0.01) in December and January and then declined significantly (p < 0.05) to 0.04 ± 0.01 in February. All clams perished by late March. The deteriorating physiological state of clams, as indicated by declining condition index, seemingly is a factor in late winter mortalities of Corbicula in the St. Clair River. In contrast to the rapid geographic spread and population increases in the southern United States, Corbicula likely will not spread rapidly throughout the Great Lakes beyond shoreline thermal refugia of heated-water discharge plumes from power plants.
Mitigation of unionid mortality caused by zebra mussel infestation: Cleaning of unionids
Exotic zebra mussels Dreissena polymorpha have infested and caused mortality of native unionids in the Great Lakes since 1986; no other such parasitism of native unionids occurs in North America. Survival of unionids threatened by zebra mussel infestation was tested by suspending uncleaned and cleaned unionids in nearshore waters of western Lake Erie. Survival was determined, and newly settled zebra mussels were removed from cleaned unionids at eight intervals that ranged from 21 d to 77 d between 5 July 1990 and 3 July 1991. After 1 year, survival rates of uncleaned and cleaned unionids were 0% and 42%, respectively. Of the 10 species examined, only individuals from 3 species ( Amblema plicata plicata , Fusconaia flava , and Quadrula quadrula ) survived 1 year. These species have relatively thick shells, which may have contributed to their survival. Removal of newly settled zebra mussels may be important to unionid survival because 98% of the zebra mussels removed after the initial cleaning were small mussels (<10 mm long) that could rapidly grow and cover unionids. At present, we do not know how zebra mussels cause mortality of unionids, but the removal of zebra mussels from unionids is the only method known that successfully reduces unionid mortality in waters colonized by zebra mussels.
Oligochaete fauna of western Lake Erie 1961 and 1982: Signs of sediment quality recovery
The oligochaete fauna at 40 stations in western Lake Erie were collected in 1982 and compared to oligochaete fauna collected similarly in 1961. A total of 34 taxa, representing 18 Tubificidae and 16 Naididae, were identified. Changes in the proportions of low, moderate, and heavy polluted sediments, as determined by ranges of total numbers of oligochaetes, indicate that, in general, heavy pollution substantially decreased near shore and moderate pollution increased and low pollution decreased in open waters over the 21-year comparison. The most common taxon, the eutrophic species, Limnodrilus hoffmeisteri , decreased in abundance in open water, indicating decreased eutrophication, whereas the distribution and abundance of other indicator taxa, including the eutrophic species L. maumeensis , L. cervix , Quistadrilus multisetosus multisetosus , and mesotrophic species Ilyodrilus templetoni and three species of Aulodrilus indicate increased eutrophication in open water. In general, oligochaete trophic indices (based on tubificid species and abundances) in traditional area designations used in 1961, the nearshore designation (<3.5 km from shore), and areas defined by cluster analysis confirm results of less eutrophic substrates near shore. However, traditional analysis indicates that low pollution was replaced by moderate pollution in open waters and cluster analysis indicates that the zone of least detectable pollution increased in open waters over the 21-year comparison. It may be that the open waters of western Lake Erie were in a stage of transition between pollution designations when sampled in 1982. The present study is valuable because it provides a baseline to assess environmental changes observed in western Lake Erie after many years of pollution abatement programs and before the exponential increase in densities of the trophic shifting zebra mussel Dreissena polymorpha.
Introduced species, zebra mussels in North America
The discovery of zebra mussels in North America in 1988 raised concern for water users because the species became abundant enough to obstruct the flow of water in human-made structures such as pipes and screens. This work reviews the biology, distribution, and impacts of zebra mussels in the context of its discovery in the Laurentian Great Lakes and its impending spread to most surface waters of North America.
Dramatic decline of unionid bivalves in offshore waters of western Lake Erie after infestation by the zebra mussel, Dreissena polymorpha
Unionid bivalves and attached epizoic zebra mussels ( Dreissena polymorpha ) were collected at one index station in 1989, 1990, and 1991 and at 17 stations in 1991 in offshore waters of western Lake Erie of the Laurentian Great Lakes. Sampling at the index station revealed that the proportion of live unionids declined from 53% in September 1989 to 17% in May–June 1990 and to 0% in September 1990: this 100% mortality coincided with heavy infestation by zebra mussels. Quantitative sampling with a Ponar grab at the 17 stations in 1991 revealed a widespread and dramatic reduction in unionid populations. In 1982, five unionid species occurred at 35% of the stations at a density of 4/m 2 , whereas in 1991, no live unionid species were found. Qualitative sampling with an epibenthic sled at the 17 stations in 1991 yielded only 4 live specimens of 2 species ( Amblema plicata plicata and Fusconaia flava ) and 187 dead specimens of 10 species. These and other results indicate that unionid populations are being negatively affected by zebra mussels in the Great Lakes. Similar impacts on unionids are expected to occur where zebra mussels become abundant throughout North America.