Small Bog Lakes Research Articles

Mercury inputs and outputs at a small lake in northern Minnesota

Storages and cycling of total mercury (HgT), methylmercury (MeHg), and Hg0 are described for Spring Lake, a small bog lake in the Marcell Experimental Forest in north-central Minnesota. We quantified photoredox transformations, MeHg photolysis, burial to the sediments, and internal and external loadings of HgT and MeHg. Atmospheric deposition was the main input of HgT; MeHg was supplied by a combination of atmospheric, near-shore wetland, and biotic (methylation) sources. HgT outputs were dominated by burial (67%), and Hg0 evasion accounted for 26% of HgT outputs. The watershed of Spring Lake is small (3.7× lake surface area), and accordingly, bog and upland runoff were minor contributors to both HgT and MeHg inputs. Wet deposition was ∼9% of total MeHg input, and other external inputs (runoff, sediment porewater) provided only an additional 7%, indicating that internal production of MeHg was occurring in the lake. Photolysis of MeHg, measured in the field and laboratory, removed ∼3× the lake mass of MeHg (20 mg) annually, and was the dominant sink for MeHg. Residence times of MeHg and HgT in the lake were 48 and 61 days, respectively, during the open-water season, compared with only 8 days for the residence time of MeHg on settling particles (seston). Photoreduction of Hg2+ to Hg0 was greater than the reverse reaction (Hg0 photooxidation), and the residence time of Hg0 in the photic zone was short (hours). Data from this study show active cycling of all the measured species of mercury (HgT, MeHg, and Hg0) and the importance of MeHg photolysis and photo-redox processes.

Ecological opportunity and levels of morphological variance within freshwater stickleback populations

The ‘ecological opportunity’ hypothesis predicts that when interspecific competition or predation is reduced, populations will exhibit increases in phenotypic variance as a result of colonization and adaptation to vacant or underutilized ecological niches (i.e. character release). We assessed this hypothesis by examining morphological diversity within stickleback populations in 40 undisturbed lakes from six islands off the mid-coast of British Columbia, Canada. Because larger lakes with well-developed littoral and limnetic zones will have greater trophic niche diversity than smaller lakes with only littoral zones, we predicted a positive association between lake size and variation in trophic morphology. Conversely, reduced vertebrate predation in small bog lakes allows increased variance in defensive structures without costs to fitness. Consistent with both predictions, we observed that phenotypic variance in two traits that are involved in feeding (gape width and pectoral fin length) increased with lake size while variability in defence structures (lateral plate number and dorsal spine length) was inversely related to lake size. Moreover, increased variance in defence morphology was accentuated in populations with severe armour reduction (spine loss, decreased plate overlap), another strong indicator of reduced vertebrate predation. In the majority of cases, these patterns were repeatable among islands, independent from the geographical distance between lakes, and arose from a combination of high variance within each of the sexes and increases in sexual dimorphism. These findings suggest that character release can be trait-specific and reflect the combined effects of competition, predation and habitat heterogeneity. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86, 297–308.

Lentic macroinvertebrate assemblage structure along gradients in spatial heterogeneity, habitat size and water chemistry.

Littoral zones of small water bodies are spatially heterogeneous habitats, harbouring diverse biotic communities. Despite this apparent heterogeneity, many studies have stressed the importance of water chemistry in determining the structure of littoral macroinvertebrate assemblages. The purpose of this study was to consider the relative importance of several spatial and water chemistry variables in explaining the patterns in the structure of macroinvertebrate assemblages in 21 lentic water bodies in northeastern Finland. Water bodies were selected to represent various habitat conditions ranging from small permanent bog ponds to small forest lakes. According to canonical correspondence analysis (CCA), the most important environmental factors related to assemblage composition were water body area, moss cover, total nitrogen and water hardness. In general, species composition in small bog ponds tended to differ from that in larger lakes with forested shoreline. Total species richness was best explained by a composite variable (PCA) describing physical habitat heterogeneity, species richness being lowest in small bog lakes with simple bottom structure and low amount of aquatic plants. Species numbers in dominant functional feeding groups were related to different environmental factors. Shredder species richness was best explained by a regression model incorporating total nitrogen and the amount of organic matter, both of which were negatively related to the number of shredder species. The number of gatherer species increased with mean substratum particle size. Scraper species richness was negatively affected by the abundance of detritus and positively affected by depth, and a model including both variables explained most of the variation. Variation in the number of predatory species was best explained by a regression model including moss cover and lake area.

An Experimental Study of Piscivore–Planktivore Interactions: Population and Community Responses to Predation

The population dynamics and behavior of an assemblage of fishes in a small bog lake were studied in a succession of whole-lake manipulations of piscivores. Total prey fish biomass declined after the addition of northern pike (Esox lucius). This decline was the result of emigration by cyprinid prey and consumption by northern pike. The emigration response of the cyprinids was dependent on cyprinid density. At high prey fish biomass, a significant portion of the loss in biomass was the result of emigration; this was not the case at low prey fish biomass. The prey fish community shifted from small-bodied soft-rayed species prior to the introduction of northern pike to species with spines or deep bodies after predator stocking. The community response was analyzed at four levels of numerical resolution: absolute, relative, and ranked abundance and presence–absence of prey species. High numerical resolution captured the dynamic short-term population responses to predation and suggests unstable community structure.

Using minnow traps to estimate fish population size: the importance of spatial distribution and relative species abundance

Relative abundance and within-lake distributions of three fishes, northern redbelly dace (Phoxinus eos), finescale dace (Phoxinus neogaeus), and central mudminnow (Umbra limi), were examined using minnow traps in Tuesday Lake, a small bog lake in the Upper Peninsula, Michigan. For these species, catches in minnow traps placed at the perimeter of the lake were 21 to 52 times higher than catches in midlake traps. Variance: mean ratios of perimeter trap catches indicated that both dace species were highly aggregated while the distribution of mudminnows was less aggregated or random. Over an 11 day period during which all fish caught were removed from the lake, catch per unit effort (CPUE) of both dace species declined in response to fish removal. In contrast, CPUE for mudminnows was low initially, increased to an asymptote and then declined only in the last 5 days of the fish removal. The patterns of CPUE for mudminnows indicated that mudminnow trapability and/or activity was reduced in the presence of high densities of dace. The low abundance of dace in traps with many mudminnows suggested mudminnows avoided traps already containing dace. Throughout the removal period, CPUE provided an accurate index of dace abundance, whereas this was true for mudmnnows only after dace populations had been reduced drastically. Therefore, in any use of minnow traps to estimate populations, both spatial distributions and relative species abundance of small fishes must be taken into account.

The foraging behavior of the central mudminnow and yellow perch: the influence of foraging site, intraspecific and interspecific competition.

The central mudminnow (Umbra limi) and yellow perch (Perca flavescens) are two species of fishes that commonly co-occur in small bog lakes in the Great Lakes region of North America. Both species are dietary generalists with a high degree of dietary overlap, and perch populations have been shown to have a strong negative effect on mudminnow populations. I compared the foraging rates of the two species in a series of laboratory experiments in which four foraging sites were simulated (open bottom substrate, water column, submerged aquatic macrophytes, and water surface). Fish were observed as they foraged singly, in monospecific pairs, and in mixed species pairs to evaluate the effects of intra- and interspecific competition on foraging success and the potential for resource partitioning based on foraging site. Single species trials showed that each species had similar foraging rates at each of the four sites. Across all sites combined, interspecific competition had a greater negative effect on the foraging success of mudminnows than did intraspecific competition. Conversely, intraspecific competition had a greater negative effect on the foraging success of perch than did interspecific competition. In mixed species trials perch took more food items from each of the four foraging sites than did mudminnows and caused shifts in site-use patterns of mudminnows. Differences in the foraging success of the two species reflected the superior ability of perch to discover the presence of food and to search rapidly for additional items, but were unrelated to handling times. These differences were linked to the species' foraging modes. The competitive superiority of perch, demonstrated in these experiments, could contribute to the negative impact of perch on mudminnow populations under natural conditions.

泥炭地池沼の研究

There is a small bog lake by the fishery village of Tokotan situated 4 km from the Akkeshi Marine Biological Station on the coast of Akkeshi Bay. The lake is elongated elliptical, 150 m in .length, 47m in greatest width, and 3.5m in greatest depth. It is surrounded by Sphagnvm-moss and is connected by a short canal with Lake Tokotan which is larger than the former and not boggy. Floating lakeward margins are 2-6m in width and mainly consist of a network of stems of Menganthes trifoliata growing thick around the lake. Colour of water is deep brown. The transparency varies from 1.15 to 1.70 in meter and is changeable dependent upon the amount of zooplankton, especially Rotatoria which are the most important group in the plankton of this bog lake. Bottom deposits are generally composed of peat debris. Thermal stratification was observed during June-September in summer and during December-March in winter, and the spring overturn is frozen through the winter stagnation period. takes place in April and May and the autumn one in October and November. The surface of the lake The water of this lake is generally acid (smallest pH value, 6.05), but surface water is sometimes weakly alkaline (greatest pH value, 7.4). Dissolved oxygen is often free in a thin layer of deeper water immediately above the bottom during the summer stagnation period.From this hog lake and also from Lake Tokotan, have been known seven kinds of fishes, including Cyprinus carpio L., Carassius auratus (L.), and Hypomesus olid a (PALLAS), etc. as usefull fishes. Some of C. a'uratus are of reddish colour in natural propagation. Such naturally reddish coloured individuals inhabiting lakes are distributed on the Pacific coast of the eastern part of Hokkaido. There have been found in this lake 2 species of Mollusks, 2 of leeches, 1 of lsopoda, and several kinds of insect larvae from Merzyantlaes zone, and also found 2 species of Mollusks and one fresh water sponge from the next Equisehon-zone of 1-2 m wide.Zooplankton is considerably superior to phytoplankton in amount. The decrease of the latter seems to be mainly due to the fact that the latter becomes prey of the former. The following pelagic animals were detected in the plankton of this lake: 2 kinds of insect larvae, 1 Hydracarina, a single form of Copepoda, 3 Cladocera, 1 Nematoda, 21 species of Rotatoria, 1 Gastrotricha, 18 Ciliata, 8 Amoebina including some of Testacea, and 2 Heliozoa. Insect larvae belonging to bottom dwellers are common in deeper water, but Copepoda and Cladocera occur more frequently in surface collections of summer plankton. The Rotatoria are the most abundant among the zooplankton and richer in the surface layer than in the deeper one.The Ciliata are very rare in surface water, being abundant near the bottom where the amount of dissolved oxygen is scarce or free. The Amoebina are not found in surface collections, but found very rarely in deeper water only in summer. The Flagellata are the most excellent quantitatively in the phytoplankton of this lake, 21 species being secured, 23 forms of Chloropbyceae, 22 species of Facillarieae, and 5 kinds of Myxophyceae, have been found. Most of these usually appear very rarely in deeper water of the lake.The small boa lake at Tokotan is of the distrophic type, but is not poor in production of zooplankton as compared with eutrophic lakes in Hokkaido.

Microfossil Succession in a Bog in Northern Wisconsin

A stratigraphical and statistical study of the microfossils in the marginal mat of a small bog lake in Vilas County, Wisconsin, was undertaken in an attempt to determine the plant succession of the region and to test a new method for determining the vertical extent of limnic and subaerial peat in a bog. The deposit in which these observations were made is known to the Wisconsin Geological and Natural History Survey as the Forestry Bog Lake, and is located near its Limnological Laboratory in Section 8, Township 41 North, Range 7 East. The depression in which the lakelet is located was formed by the melting of a buried ice mass in the pitted outwash plain of the Early Mankato Ice (Fourth Wisconsin). The soils surrounding the depression are predominantly sandy, but also contain lenses of gravel. The area of the lake, which is in the center of the bog, is 993 square meters. Its maximum depth is 2 meters. The original area and depth were much greater. Very early in the history of the Forestry Bog Lake there was a connection on the southern side with Trout Lake. How long this persisted is impossible to state, but the condition of the topography suggests that it was very brief and may have been connected only during the melting of the glacial ice at this point. The lakelet (fig. 1) is in the late stage of old age, as is shown by the presence of organic soils, shallow water and an irregular shoreline of peat (Wilson, '35). According to Fassett ('30), the plants growing upon the peat bog are Sphagnum sp., Sarracenia purpurea, Mlonotropa uniflora, Smilacina trifolia, Chioagenes hispidula, Rynchaspora alba, Picea inariana bearing A rceuthobium pusillum, Eriophorunt virginicuiv, Larix laricina, Carex oligosperma, C. pauciflora, C. trisperma, Chamnaedaphne calyculata, Leduni groenlandicum, Gaultheria procumbens, Vaccinium oxycoccos, Menyanithes trifoliata, Kalmia poli* From the Limnological Laboratory of the Wisconsin Geological and Natural History Survey and Coe College. Report No. 64. The publication of the illustrations in this article was provided for by funds other than those of the Ecological Society of America.