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Donald W. Schloesser

Publications and source records attributed to Donald W. Schloesser.

28 records · Page 2Linked to original sources
USGS1988

Seasonal growth of the exotic submersed macrophyte Nitellopsis obtusa in the Detroit River of the Great Lakes

Seasonal growth and occurrence of an exotic submersed aquatic macrophyte, Nitellopsis obtusa , was monitored at the head of the Detroit River of the Great Lakes from June 1984 to April 1985. Nitellopsis obtusa first appeared in early July, increased in biomass from July to September, remained at relatively high biomass from September to late January, and decreased substantially as ice breakup began in mid-February. By March it had become senescent, lacking chlorophyll and disintegrating easily. Nitellopsis obtusa was therefore available as a source of food and shelter for benthic and juvenile fish populations in late fall and winter, when other macrophytes were absent.

Canadian Journal of Botany↗
USGS1988

Relationships of phytomacrofauna to surface area in naturally occurring macrophyte stands

Most studies of the relationships between freshwater macrophytes and phytomacrofauna, or the macroinvertebrates associated with the macrophytes, have been based on individual plant collections or samples from monotypic plant stands. We describe the phytomacrofauna assemblages within naturally occurring, taxonomically mixed stands, and consider how macrophyte surface area and plant morphology influenced phytomacrofauna diversity and abundance. Samples of submersed macrophytes and phytomacrofauna were collected April-November 1979 in Anchor Bay of Lake St. Clair. Only the portions of macrophytes within the water column and invertebrates from above the sediment were considered. Densities of phytomacrofauna were not consistently related to fluctuations in macrophyte surface area, indicating that the use of macrophyte structure by the invertebrates changed during the year. Both the abundance and species richness of the phytomacrofauna were strongly related to macrophyte species richness reflecting the response of the invertebrates to the structural heterogeneity in taxonomically mixed stands. Vertically heterogeneous stands with an understory of Chara and an overstory of vascular macrophytes, for example, were likely to contain more invertebrates than stands with only one macrophyte taxon.

Journal of the North American Benthological Societ↗
USGS1987

Use of low-altitude aerial photography to identify submersed aquatic macrophytes

The feasibility of using low-altitude aerial photography to identify beds of submersed macrophytes is demonstrated. True color aerial photos and collateral ground survey information for submersed aquatic macrophyte beds at 10 sites in the St.Clair-Detroit River system were obtained in September 1978. Using the photos and collateral ground survey information, a dichotomous key was developed for the identification of six classes - beds of five genera of macrophytes and one substrate type. A test was prepared to determine how accurately photo interpreters could identify the six classes. The test required an interpreter to examine an unlabeled, outlined area on photographs and identify it using the key. Six interpreters were tested. One pair of interpreters was trained in the interpretation of a variety of aerial photos, a second pair had field experience in the collection and identification of submersed macrophytes in the river system, and a third pair had neither training in the interpretation of aerial photos nor field experience. The criteria that we developed were applied equally well by the interpretors, regardless of their training or experience. Overall accuracy (i.e., omission errors) of all six classes combined was 68% correct, whereas, overall accuracy of individual classes ranged from 50 to 100% correct. Mapping accuracy (i.e. omission and commission errors) of individual classes ranged from 36 to 75%. Although the key developed for this study has only limited application outside the context of the data and sites examined in this study, it is concluded that low-altitude aerial photography, together with limited amounts of collateral ground survey information, can be used to economically identify beds of submersed macrophytes in the St. Clair-Detroit River system and other similar water bodies.

Conference Paper↗
USGS1986

Distribution and habitat of Nitellopsis obtuse (Characeae) in the Laurentian Great Lakes

Nitellopsis obtusa , a macroalga (Characeae) native to Europe and Asia, was found in U.S. waters of the St. Clair-Detroit River system in 1983, thus extending the range of this taxon into the Laurentian Great Lakes about 850 km from the St. Lawrence River where it was first discovered in North America in 1978. Its occurrence only in water frequented by commercial shipping vessels suggests that it is distributed via this mechanism. In the St. Clair-Detroit River system, N. obtusa was collected with a Ponar grab at four locations, and with a grapnel at one additional location. It was the ninth most frequently found macrophyte and it was most abundant at Belle Isle in the Detroit River, where the mean dry-weight biomass in Ponar samples was 0 g m -2 in June, 37 g m -2 in August, and 32 g m −2 in September. Maximum biomass of this taxon in one Ponar grab at this location was 289 g m -2 in September. The alga occurred primarily in water of relatively low current velocity (11.3 cm s −1 ) and in association with Vallisneria americana, Myriophyllum spicatum, Potamogeton richardsonii, Najas flexilis , and Elodea canadensis .

Hydrobiologia↗
USGS1986

Distribution of submersed macrophytes in the St. Clair-Detroit River System, 1978

An extensive survey was conducted in fall 1978 to determine the distribution and abundance of submersed macrophytes through the St. Clair-Detroit River system from Lake Huron to Lake Erie. Submersed macrophytes, representing 19 taxa, were widely distributed in the system, being found on 358 km 2 (30%) of the total 1185 km 2 of substrate surveyed. Of the 19 taxa identified, 8 common taxa were found on 20 to 121 km 2 of substrate. These commonly found taxa, in decreasing order of substrate coverage were Characeae, Vallisneria americana , Najas flexilis , Myriophyllum spicatum , Elodea canadensis , Potamogeton richardsonii , Potamogeton spp. (narrow-leaf forms), and Heteranthera dubia . In general, macrophyte beds of low, medium, and high biomass covered much less area but a higher proportion of the available substrate in the St. Clair and Detroit rivers than in Lake St. Clair.

Journal of Freshwater Ecology↗
USGS1985

Growth of submersed macrophyte communities in the St. Clair - Detroit River system between Lake Huron and Lake Erie

Growth of submersed aquatic macrophytes was determined from observation and on the basis of biomass of samples collected from April to November 1978 at seven study sites in a major river system of the Great Lakes, the St. Clair – Detroit river system between Lake Huron and Lake Erie. Growth usually began between April and June, peaked between July and October, and decreased by late November. Maximum biomass at six of the seven sites (118–427 g dry weight m −2 ) was similar or greater than that reported in other rivers at similar latitudes. Seasonal growth of the abundant taxa followed one of three seasonal patterns at each study site: one dominant taxon grew alone; codominant taxa grew sympatrically without species succession; and codominant taxa grew sympatrically with species succession. Differences in growth and seasonal succession of some taxa were apparently caused by the presence or absence of overwintering plant material, competition, and life-cycle differences.

Canadian Journal of Botany↗
USGS1984

Distribution of Eurasian watermilfoil, Myriophyllum spicatum , in the St. Clair-Detroit River system in 1978

Submersed macrophytes were surveyed at 595 stations located throughout the St. Clair-Detroit River system between Lakes Huron and Erie, 23 August to 13 October 1978. Eurasian watermilfoil ( Myriophyllum spicatum ), first recorded in the system in 1974, became the fourth most common submersed macrophyte in the system by 1978. However, it has not been reported as a widespread nuisance in this system as it has in many other large water bodies in the United States. Observations made during the present study, and interpretation of an aerial photograph, suggest that M. spicatum was a minor nuisance to small boat navigation in portions of the system. Information presented in this study provides a baseline against which future changes in the occurrence of M. spicatum in the St. Clair-Detroit River system can be measured.

Journal of Great Lakes Research↗
USGS1984

Life cycle of a mayfly Hexagenia limbata in the St. Marys River between Lakes Superior and Huron

Length-frequency distribution curves of Hexagenia limbata nymphs collected in May, August, and October 1974 and May 1975 in the St. Marys River between Lakes Superior and Huron were bimodal for each sampling period. These curves, combined with interpretation of nymphal emergence period and mean surface water temperatures, indicate that the population of Hexagenia nymphs in the St. Marys River is composed of two year classes or cohorts. One cohort emerges per season, 2 years after egg deposition.

Journal of Great Lakes Research↗
USGS1983

The occurrence of oil and the distribution of Hexagenia (Ephemeroptera: Ephemeridae) nymphs in the St. Marys River, Michigan and Ontario

We sampled benthos from the St. Marys River in May 1974 and May 1975 to determine visibly the occurrence of sorpted oil and the distribution of nymphs of the burrowing mayfly Hexagenia in the bottom of the Lake George and Lake Nicolet channels. Results of our survey showed that, between 1967 and 1974-75, the occurrence of oil in the substrate of the Lake George Channel had advanced from 16 km to 30 km downstream from the point where oil is discharged at Sault Ste. Marie, Ontario. Absence or low densities of nymphs coincided with the presence of oil in the sediments. In the Lake Nicolet Channel, evidence of oil pollution was meager and the density of Hexagenia nymphs was generally high.

Freshwater Invertebrate Biology↗