David R. Barton

Dimensions of Riparian Buffer Strips Required to Maintain Trout Habitat in Southern Ontario Streams

Abstract The relationships between riparian land use and environmental parameters that define the suitability of southern Ontario streams for trout were examined for 40 sites on 38 streams. Weekly observations of maximum and minimum temperature, coarse and line suspended matter, and discharge were made during June, July, and August 1980. Land use was determined from aerial photographs of each stream. Fish were surveyed at each site during August by electrolishing and seining. The only environmental variable which clearly distinguished between trout and nontrout streams was weekly maximum water temperature: streams with trimean weekly maxima less than 22 C had trout; warmer streams had, at best, only marginal trout populations. Trout streams tended to have low concentrations of fine suspended solids and a more stable discharge, but so did many of the other streams. Water temperature, concentration of fine particulate matter, and variability of discharge were inversely related to the fraction of the upstrea...

Effects of Round Gobies (Neogobius melanostomus) on Dreissenid Mussels and Other Invertebrates in Eastern Lake Erie, 2002–2004

From 2001 through 2004, the densities of Dreissena bugensis and Amphipoda (Gammarus fasciatus and Echinogammarus ischnus) decreased by 94% and 85%, respectively, in the rocky northern nearshore (2–10 m depth) zone of eastern Lake Erie. Densities of Chironomidae and Oligochaeta did not change. The decline in D. bugensis was most evident for individuals with shell lengths in the 3 to 14 mm range. The mean (±SD, n) abundance of round gobies (Neogobius melanostomus) at 10-m depth increased from 6.5 (± 1.9, 12)/m2 in 2001 to 14(±1.0, 15/m2 in 2002. Analyses of stomach contents in 2001 and 2003, and stable isotopes of carbon in prey and muscle tissue in 2002, indicated that the diet of round gobies in 2001 was predominately dreissenids, but that chironomids and amphipods became more important as the abundance of appropriately sized mussels declined. Round gobies collected in 2003 contained more individual prey, but less total mass of prey than did gobies collected in 2001. Our observations suggest that round gobies probably became food-limited in eastern Lake Erie by 2002.

Wave-Zone Macrobenthos of the Exposed Canadian Shores of the St. Lawrence Great Lakes

Abstract Two series of qualitative collections of the benthic macroinvertebrates inhabiting the wave-zone (0-2m) along the exposed Canadian shores of the St. Lawrence Great Lakes were made in the summer of 1974. This fauna consisted largely of typically lotic water forms, including Heptageniidae (Ephemeroptera) and Hydropsychidae (Trichoptera). The variety and relative abundance of invertebrates was directly related to substrate stability. Insects other than chironomids were rare in Lake Ontario and hypotheses to explain this different fauna are presented.

Dreissenid phosphorus excretion can sustain C. glomerata growth along a portion of Lake Ontario shoreline.

ABSTRACT One of the effects of the dreissenid invasion into the Laurentian Great Lakes appears to be a resurgence in the abundance of the nuisance alga Cladophora glomerata which experienced a marked decline following phosphorus abatement in the late 1970s and early 1980s. A subsidy of bioavailable phosphorus excreted by dreissenid mussels could be an important mechanism facilitating the growth of C. glomerata. To assess the importance of phosphorus released by mussels to C. glomerata growth in the nearshore, we conducted a survey of mussel distribution and abundance followed by in situ experiments designed to measure dreissenid phosphorus excretion rates. Average dreissenid mussel abundance in our study area was 3674 individuals/m2, with an average biomass of 52.2 g of shell free dry mass/m2. The mussels excreted bioavailable soluble reactive phosphorus at an average rate of 7.02 µg SRP/g shell free dry mass/hour, contributing about 11 t of soluble reactive phosphorus to our study area over the C. glomerata growing season. Dreissenids appear to be an important source of recycled bioavailable phosphorus to the nearshore, supplying more soluble reactive phosphorus to our study area than local watercourses and WWTPs, and more phosphorus than is required to sustain local C. glomerata growth.

Re-engineering the eastern Lake Erie littoral food web: The trophic function of non-indigenous Ponto-Caspian species

ABSTRACT The trophic roles of key Ponto-Caspian invaders (quagga mussels Dreissena bugensis, amphipods Echinogammarus ischnus and round goby Apollonia melanostomus) within the littoral food web of eastern Lake Erie were quantified using stable isotopes (&dgr;13C, &dgr;15N). A dual stable isotope parameter search with a mass balance component was used to assess the isotopic importance of quagga mussels and amphipods as dietary items to two size classes of round goby. The utility of the mass balance simulation was also evaluated as a tool to approximate isotopic contributions of feasible prey and identify gaps incurred by “missing” prey items not included in the sampling. The mass balance dietary simulation, confirmed by stomach content data, indicated that isotopically important prey to small round goby (<11.2 cm) were chironomids and Ponto-Caspian amphipods, while large round goby (≥11.2 cm) showed strong preference for quagga mussels. The dietary mass balance simulation output also supported the isotopic importance of round goby to the somatic growth of smallmouth bass, rock bass and freshwater drum. The isotopic mass balance output for yellow perch was more ambiguous, which may be in line with their known broadly omnivorous diet. The white bass output was in line with published data indicating increasing consumption of round goby for this species, while the brown trout output strongly favoured alewife isotopic contributions. However for white perch and walleye, the mass balance simulations were not in line with their known published diets in Lake Erie, probably due to a lack of key prey items in the sample set (e.g. zooplankton for white perch and shiner species for walleye). As expected, the Ponto-Caspian species have integrated themselves into the littoral food webs, and the “quagga mussel-round goby-smallmouth bass” food chain forms one of the key components within the trophodynamics of Lake Erie.

Benthic Invertebrates of the Nearshore Zone of Eastern Lake Huron, Georgian Bay, and North Channel

Samples of benthic invertebrates were collected by divers during 1980 from 86 stations in the nearshore zone (depths of 5 to 20 m) of Lake Huron, Georgian Bay, and North Channel. Six general categories of substratum were encountered: rock, gravel, hard clay, sand, silt/sand, and silt. Abundance of invertebrates varied with depth and substratum, ranging from 456 m−2 to 45,701 m−2. Clay and gravel usually supported the largest populations, rock the smallest. A total of 218 taxa were recognized, including a first record of the naidid Ripistes parasitica in the western hemisphere. With only a few exceptions, individual taxa were distributed throughout the study area. The most abundant groups were Nematoda, Oligochaeta, Mollusca, and Chironomidae. Ephemeroptera and Trichoptera occurred at 83% of 5 and 10-m stations. Nine communities of invertebrates were recognized on the basis of ordination analysis. Differences in community composition appeared to reflect degree of exposure to wave action and local geology. Comparison of these results with those of earlier studies illustrated the much greater efficiency achieved through direct sampling by divers. Estimates of invertebrate standing stocks were up to an order of magnitude greater in the present survey, and the variety of organisms was much greater since all types of substrata could be sampled. There were no indications of increased eutrophication or unusual environmental stress within the study area.

Distribution and Abundance of Burrowing Mayflies (Hexagenia spp.) in Lake Erie, 1997–2005

ABSTRACT Burrowing mayflies (Hexagenia limbata and H. rigida) recolonized sediments of the western basin of Lake Erie in the 1990s following decades of pollution abatement. We predicted that Hexagenia would also disperse eastward or expand from existing localized populations and colonize large regions of the other basins. We sampled zoobenthos in parts of the western and central basins yearly from 1997–2005, along the north shore of the eastern basin in 2001–2002, and throughout the lake in 2004. In the island area of the western basin, Hexagenia was present at densities ≤1,278 nymphs/m2 and exhibited higher densities in odd years than even years. By contrast, Hexagenia became more widespread in the central basin from 1997–2000 at densities ≤48 nymphs/m2 but was mostly absent from 2001–2005. Nymphs were found along an eastern basin transect at densities ≤382/m2 in 2001 and 2002. During the 2004 lake-wide survey, Hexagenia was found at 63 of 89 stations situated throughout the western basin (≤1,636 nymphs/m2, mean = 195 nymphs/m2, SE = 32, N = 89) but at only 7 of 112 central basin stations, all near the western edge of the basin (≤708 nymphs/m2), and was not found in the eastern basin. Hexagenia was found at 2 of 62 stations (≤91 nymphs/m2) in harbors, marinas, and tributaries along the south shore of the central basin in 2005. Oxygen depletion at the sediment-water interface and cool temperatures in the hypolimnion are probably the primary factors preventing successful establishment throughout much of the central basin. Hexagenia can be a useful indicator of lake quality where its distribution and abundance are limited by anthropogenic causes.

Oberservations on the life histories and biology of Ephemeroptera and Plecoptera in northeastern Alberta

Abstract During studies of the environmental effects of oil sands development in northeastern Alberta in 1976–1977, 36 species of Ephemeroptera and 21 of Plecoptera were collected using various techniques. Individuals of 18 mayflies and 17 stoneflies were taken in numbers sufficient to determine their basic life histories and habitat preferences. Among the mayflies, 8 (possibly 10) species exhibited fast seasonal development, 8 slow seasonal, and 2 non‐seasonal. Among the Plecoptera, these patterns were exhibited by 5, 7 and 5 species, respectively. Nymphs of most fast seasonal mayflies developed in pools and silty backwaters, often in association with aquatic macrophytes. Slow seasonal mayflies and most stoneflies were found in riffles, or on bedrock and debris in the Athabasca River. The fauna included a mixture of Eastern, northern and cordilleran species. Eastern species probably reached the Athabasca River drainage via glacial Lake Agassiz.

Distribution of Some Common Benthic Invertebrates in Nearshore Lake Erie, with Emphasis on Depth and Type of Substratum

The distributions and qualitative depth and sediment preferences of the 20 most common benthic invertebrate taxa were determined from nearly 600 Shipek grab samples collected from the nearshore zone of Lake Erie in 1972 and 1973. Cryptochironomus, Potamothrix moldaviensis, Stylodrilus heringianus, Micropsectra, and Pontoporeia hoyi were most commonly found on sandy sediments (gravelly sand, sand) at various depths. Pseudochironomus sp., Chironomus (2 spp.), Asellus racovitzai, Valvata sincera, Limnodrilus cervix, L. hoffmeisteri, Tubifex tubifex, and Helobdella stagnalis exhibited more or less distinct depth distributions on muddy sediments (muddy sand, sandy mud, mud). Spirosperma ferox was equally common on all substrata, but preferred deeper water. The observed distributions of Micropsectra and Chironomus spp. were also related to the time of sampling. No taxon was found more frequently than expected by chance on very coarse sediments (bedrock, pebbles, gravel). The distributions of six other taxa were not significantly related to depth or type of substratum, but neither were they randomly distributed within the study area. The distributions of at least four species (S. ferox, Heterotrissocladius changi, Pseudochironomus, Gammarus fasciatus) appeared to be influenced by water quality.

The effects of synthetic crude oil on microbial and macroinvertebrate benthic river communities—Part I: Colonisation of synthetic crude oil contaminated substrata

Abstract An acute, short-term synthetic crude oil spill into a northern brown-water river in Alberta, Canada, was simulated by dipping limestone bricks into the oil and then examining their microbial and macroinvertebrate colonisation under conditions of light and dark. A reduction to Lepidostoma , the Chironomidae and the Naididae. On oiled bricks in the dark the only significant changes were an increase in numbers of bacteria and Tanypodinae and a reduction in Gastropoda and Baetis sp.; all other parameters did not differ significantly from the control. It therefore appears that synthetic crude oil has a stimulatory action upon bacterial, algal and macroinvertebrate benthic colonisation but one that is not apparent under conditions of low light. The traditional approach of assessing the impact of a pollutant through the use of ‘indicator species’ needs to be reconsidered to include the supporting food web.