Abundance, growth, and food supply of white suckers (Catostomus commersoni) in relation to lake morphometry and pH

Twenty-three populations of white suckers Catostomus commersoni from Ontario lakes were investigated to determine if growth was density-dependent and if the abundance of chironomid larvae in the lake littoral zone was an important factor influencing growth. White sucker population sizes were estimated with either the Petersen mark–recapture or the catch-per-unit-effort method. White sucker fork length at age was back-calculated from the first pectoral fin ray. Each lake was divided into three thermal zones based on the position of the thermocline, and the benthos was quantified from 60 core samples prorated over the three zones. Canonical correlation and redundancy analyses indicated that the abundance of benthos, especially chironomids in the littoral zone, was a good predictor of white sucker growth. Growth was not so important in explaining benthos abundance. Regression and correlation analyses indicated white suckers from lakes with more abundant chironomid larvae in littoral zones and low white sucker population densities tended to increase in length faster than white suckers from lakes with less abundant littoral chironomid larvae and high white sucker population densities. Significant negative correlations were found between white sucker population size and abundance of measured benthos. This study provided the first evidence that white sucker growth may be constrained by both population density and food supply.

Bone was decalcified in fish from three acid lakes and manganese was increased greatly in bone of fish from the most acid lake. The mean centrum calcium content of white suckers (Catostomus commersoni) captured in George Lake (pH 4.65) was 16% lower than in white suckers from three lakes with near-neutral pH levels. In two other acid lakes, King (pH 5.08) and Crosson (pH 5.36), centrum calcium was reduced significantly in white suckers. Centrum manganese was elevated fivefold in white sucker from recently acidified George Lake, and tended to be elevated in this species from King Lake. White suckers from George Lake exhibited shorter caudal vertebrae and some of these fish had deformed caudal fins. These anomalies may be indicative of bone demineralization. All of the study lakes were located in south-central Ontario, including the La Cloche Mountains, North Bay, Algonquin, Haliburton, and Muskoka.Key words: lake acidification, bone composition, calcium, manganese, white sucker

Alewives were collected by nighttime gill netting during summer 1999 from 12 Connecticut lakes that support landlocked populations to determine relationships between population characteristics and physicochemical lake variables. Mean catch-per-unit-effort (CPUE) ranged from 0.2 to 16.4 age-1 and older alewives per net hour. Maximum ages of alewives among lakes ranged from two to five years, and mean back-calculated length-at-age-1, used to index growth rate, ranged from 78 to 146 mm. Mean back-calculated length-at-age-1 was positively correlated with mean relative condition factor (Kn), watershed area:lake surface area ratio, watershed area:lake volume ratio, lake surface area:lake volume ratio, conductivity, total nitrogen, alkalinity, calcium, magnesium, and chlorophyll a, and negatively correlated with retention time, maximum lake depth, mean lake depth, and transparency. Mean Kn ranged from 0.93 to 1.23 and was positively correlated with mean back-calculated length-at-age-1, watershed area:lake volume ratio, lake surface area:lake volume ratio, total nitrogen, chlorophyll a, and potassium, and negatively correlated with maximum lake depth and transparency. Growth and Kn of alewives were highest in shallow, productive lakes with low transparencies. CPUE was not related to growth rate or to any physicochemical lake variable.

Atmospheric contamination by sulfur dioxide in the Sudbury region and the associated acidification has reduced population densities of fishes in the La Cloche Mountain lakes, 33–90 km away. Surviving rock bass (Ambloplites rupestris) responded to decreased abundance with increased growth rate. Variation in abundance among surviving populations could be monitored by means of individual growth rates and mean lake depth. Our findings suggest that growth rate of fishes, in conjunction with the morphoedaphic index, may serve as an indicator of environmental stress. Key words: environmental indicator, environmental stress, lake acidification, fish growth rate, morphoedaphic index, population density, rock bass

Pathogenesis of skin and liver neoplasms in white suckers from industrially polluted areas in Lake Ontario

Can we estimate the lake mean depth and volume from the deepest record and auxiliary geospatial parameters?

White sucker (Catostomus commersoni) in three acid lakes (pH 4.90, 5.56, and 5.58) frequently matured at older ages and larger sizes and had shorter reproductive life spans than white sucker in two circumneutral lakes (pH 6.30 and 6.35). Reproductive life span was positively correlated in females (r = 0.97) and males (r = 0.85) with lake pH. In the acid lakes, elevated mortality rates coincided with the onset of sexual maturity whereas in circumneutral lakes, mortality rates did not change at maturity. Ovarian weight and ovarian somatic index values were not significantly different between females from two acid and two circumneutral lakes. Values of fecundity, ova dry weight, testicular weight, and testicular somatic index of fish in acid lakes were either significantly greater than or equal to values in white sucker from circumneutral lakes. Results are discussed within the context of life history theory.

The liver, kidney, muscle, and bone tissues of white suckers (Catostomus commersoni) captured from six lakes in south-central Ontario were analyzed for Cd content. The lakes ranged in pH from 4.8 to 6.4 and contained elevated Cd concentrations in the recently deposited sediments. Cd was found to be bioaccumulating in the livers of fish from both acid and circumneutral lakes, with fish from (acid) George Lake (ages 2–5) and (neutral) Red Chalk Lake (ages 7–14) containing similar concentrations. Calculated growth constants for each of the six populations revealed considerable variations in fish growth rates. A method is presented which represents the age, weight, and tissue Cd concentrations data for the six populations such that interlake comparisons of metal bioavailability can be made with the possible effects that the different fish growth rates may have on rates of metal accumulation factored out. When presented in this manner, our results imply that, on the linear portion of the growth curve, the growth rates of each population, and not effects due to lowered lake pH, can account for the concentrations of Cd in five of the six fish populations. Therefore, since tissue-metal concentrations in fish from stressed lakes will be dependent on both metal bioavailability and fish growth rates, it is essential that these be reported together.

The concentrations of 17 elements were determined in the bone of white suckers (Catostomus commersoni) netted from 5 acid (pH range 4.8 to 5.8) and 2 circumneutral (pH=6.2 and 6.3) lakes in south-central Ontario. The bone Ca:P dry weight ratios were similar (2.0:1) for all fish populations except those of George Lake (pH=4.8) which showed a significantly lower Ca:P ratio (1.9:1, P < 0.05). Magnesium was also lower in the bone of these fish and in fish from 2 other acid lakes. Only bone Ba and S concentrations in the 7 fish populations correlated significantly to lake pH (R=-0.9 and R=-0.8, respectively, P < 0.05). Bone Mn concentrations correlated to dissolved lake Mn concentrations (R=0.8, P < 0.05), and was 7 fold greater in the bone of fish from George Lake and 2 fold greater in King Lake (pH=5.0) fish, vs fish from the 2 circumneutral lakes. Bone Zn was significantly greater in white sucker from George Lake, and tended to be higher in this species from King Lake, compared to all other fish populations. Bone concentrations of Fe, Cu, Ni and Al showed no apparent trends among the 7 fish populations. Cd, Co, Cr, Mo, V and Be were not detected. The occurrence of a reduced Ca:P ratio coincident with the highest concentrations of Mn, Zn and Ba in the bone of fish from the most acidified environment suggests that increased metal concentrations which occur in surface waters coincident with lake acidification may affect bone calcification.

Adult white suckers were collected from four lakes in Maine that ranged in pH from 7.0 to 5.4. The gastrointestinal tract and remainder of the carcass of fishes of similar age and size from each lake, and gills from additional fishes of similar size, were analyzed for Al, Cd, Pb, and Zn. Carcasses were also analyzed for Hg. Concentrations of Al, Cd, and Pb were highest in the gastrointestinal tract and lowest in the carcass; Zn concentration was highest in the gill. For carcass, all metals except Al differed significantly among lakes, for gill tissue Cd and Pb differed, and for gastrointestinal tract, only Cd differed among lakes. Where differences were significant, patterns among lakes were similar in each tissue analyzed. Concentrations of Cd, Hg, and Pb were negatively correlated with lake water pH, acid neutralizing capacity (ANC), Ca, and lake:watershed area, and positively correlated with lake water SO4, indicating that concentrations were higher in fish from more acidic lakes. Zinc concentrations in gills were unrelated to lake acidity, and carcass concentrations were higher in the less acidic lakes, which is the opposite of the pattern for the other metals studied. Zinc in gastrointestinal tract did not differ among lakes. Although the lakes we studied were located in undisturbed watersheds and did not receive any point source discharges, fish metal concentrations were comparable to or higher than those reported from waters receiving industrial discharges.

Information about lake morphometry (e.g., depth, volume, size, etc.) aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate measures of lake morphometry, particularly lake depth, are usually collected on a lake-by-lake basis and are difficult to obtain across broad regions. To span the gap between studies of individual lakes where detailed data exist and regional studies where access to useful data on lake depth is unavailable, we developed a method to predict maximum lake depth from the slope of the topography surrounding a lake. We use the National Elevation Dataset and the National Hydrography Dataset – Plus to estimate the percent slope of surrounding lakes and use this information to predict maximum lake depth. We also use field measured maximum lake depths from the US EPA's National Lakes Assessment to empirically adjust and cross-validate our predictions. We were able to predict maximum depth for ∼28,000 lakes in the Northeastern United States with an average cross-validated RMSE of 5.95 m and 5.09 m and average correlation of 0.82 and 0.69 for Hydrological Unit Code Regions 01 and 02, respectively. The depth predictions and the scripts are openly available as supplements to this manuscript.

Concentrations of 14 elements (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Sn, Tl, V, and Zn) were measured in the dorsal muscle of omnivorous white suckers and brown bullheads, fish likely to ingest sediment while feeding. The fish were collected in two acidic Adirondack lakes known to have elevated concentrations of several of these elements in their surface sediment. Trace element concentrations in the muscle of the white suckers and brown bullheads were compared with government guidelines for edible fish and survey data for concentrations present in commercial species. Only the largest white sucker exceeded the U.S. Food and Drug Administration's guidelines for Hg in food of 1 ppm (wet wt). Concentrations of all the other elements measured were at low or innocuous levels in the edible muscle. A significant positive correlation was found between body weight and Hg concentrations in both species. Zinc was negatively correlated for the same parameters in white suckers. With the possible exception of Hg, our results indicate that elevated levels of potentially toxic elements in the surface sediment of the two acidic Adirondack lakes are not reflected in the edible muscle of the omnivorous bottom feeding fish present in these systems.

The distribution of benthic macroinvertebrates was studied in deep Lake Motosu (oligotrophic lake), Japan. Bathymetrical sampling surveys were carried out using a standard Ekman grab at each of 16 stations in the lake on 8 March 2013. The average densities of the benthic community for all the stations were 2185 ind./m2, comprised principally of Tubifex tubifex (Muller) 23.4%, Asellus hilgendorfi Bovallius 4.9% and chironomids 65.8%. T. tubifex and chironomids inhabited the entire lake bottom, with higher densities in the shallower region (25 m>) than in the deeper region (ca. 120 m). On the other hand, the density of A. hilgendorfi increased with water depth and was highest in the deeper regions (>70 m). The densities of chironomid larvae were lower in the deeper region, with fewer chironomid larvae located in the center of the lake (637 ind./m2). The most abundant species, Micropsectra yunoprima Sasa, exhibited the widest distribution from 10.0 m to 121.0 m (mean density 926 ind./m2), followed by Procladius choreusi (Meigen) from 10 m to 74.1 m (mean density 365 ind./m2). The results of this study were compared to previous data by Kitagawa (1973) on chironomid larvae. The densities of these chironomid larvae increased throughout the whole lake in 2013. The water quality has not undergone a major change since the 1970’s. In this study, the number of M. yunoprima larvae has shown a tendency to increase, especially in shallower regions; where they are widely distributed, suggesting the continuation of favorable bottom condition for larvae since the 1970’s.

Lake 223 in the Experimental Lakes Area, northwestern Ontario, was experimentally acidified with sulfuric acid from 1976 (initial average pH 6.49) to 1981 (average pH 5.02), and then maintained at pH 5.02 to 5.13 from 1981 to 1983. Lake trout (Salvelinus namaycush), white sucker (Catostomus commersoni), fathead minnow (Pimephales promelas), and slimy sculpin (Cottus cognatus) were abundant at the onset of acidification. A decline in the abundance of fathead minnow began in 1979 (pH 5.64), and was followed first by a rapid increase in number of pearl dace (Semotilus margarita) in 1980 (pH 5.59) and then a rapid decrease in 1982 (pH 5.09). The abundance of slimy sculpin decreased rapidly in 1979. Abundances of lake trout and white sucker increased during the early years of acidification, but declined following consecutive recruitment failures starting in 1980 for trout and in 1981 for white suckers. By 1982 recruitment had ceased for all Lake 223 fishes. Survival of lake trout [Formula: see text] age 1 decreased in 1982 and 1983, but no other changes in survival of fish [Formula: see text] age 1 were detected for lake trout or white sucker. By spring 1983 many lake trout were emaciated due to losses of the lake trout food organisms. No changes in growth of lake trout and white suckers occurred during the initial years of acidification, but growth of lake trout slowed in 1982 and growth of white sucker increased in 1979.

Blood serum and other tissues of white suckers (Catostomus commersoni) and other species of fish have been examined in a preliminary effort to understand losses of fish from acid lakes. Maturing females of highly acid George Lake failed to show the normal degree of increase in serum Ca over males captured in the same location. Elevated serum Ca was always observed in females, relative to males, from non-acid locations when maturation stages were similar. A number of body tissues were examined to determine whether the distributions of Ca or other elements were altered and the only striking change evident in fish from George Lake was their high Mn content. Bone in particular was examined for N, Na, Mg, P, K, and Ca and no evidence of demineralization was found. Other tests such as hemoglobin indicated that an anticipated adaptive response to asphyxia was absent. Our results indicate that potential mechanisms of fish losses such as asphyxia and starvation are unlikely to have been significant, however, they do not firmly establish any alternate mechanism. As a working hypothesis we suggest that Ca dynamics may limit ovarian development and that absorption of this metal at exchange surfaces may be impaired.