Nutrient Budgets for Lake Erie, 1970

1976 ◽  
Vol 33 (3) ◽  
pp. 520-536 ◽  
Author(s):  
N. M. Burns

Budgets for the quantities of water, chloride, and phosphorus entering and leaving Lake Erie during the year of 1970 have been developed. The phosphorus budget was broken down into basin budgets which were further subdivided into epilimnion budgets for the Central and Eastern basins. Epilimnion budgets for soluble inorganic nitrogen (SIN) and soluble reactive silica (SRS) were also developed. The average coefficients of elimination by sedimentation of the phosphorus within each basin were 4.0, 0.38, and 0.18%/day for the Western, Central, and Eastern basins, respectively. The phosphorus elimination was found to be inversely related to mean basin depth but directly related to the phosphorus concentration of the water. The epilimnion budgets showed that during the summer the internal loading of SRS to the epilimnion was greater than the uptake of SRS by phytoplankton growth. The epilimnion budget of SIN demonstrated a massive uptake of the material during the summer, which was only partially replenished. The loss rate of phosphorus from the Central and Eastern basin epilimnia decreased as the summer progressed, to the extent that there was a net gain of phosphorus in the Eastern basin epilimnion toward the end of the summer. It is believed that this resulted from significant upward transport of phosphorus from the hypolimnion to the epilimnion by flagellate species of phytoplankton.

1976 ◽  
Vol 33 (3) ◽  
pp. 564-573 ◽  
Author(s):  
N. M. Burns ◽  
J. D. H. Williams ◽  
J.-M. Jaquet ◽  
A. L. W. Kemp ◽  
D. C. L. Lam

A budget for phosphorus retention in Lake Erie during 1970 has been drawn up. Phosphorus associated with sand-sized particles (> 63 μm) was excluded. Retention of apatite phosphorus (AP) and nonapatite phosphorus (NAP) within each of the three basins of the lake (Western, Central, and Eastern) was estimated in each case by two independent methods. The two estimates of retention of total phosphorus within the entire lake agreed to within 9.5% of their mean. The estimates of AP retention within the Western basin also agreed well. However, the input–output balance estimates of AP retention in the Central basin and of NAP retention in the Western and Central basins greatly exceeded the corresponding sedimentation values, while in the Eastern basin this pattern was reversed. The AP discrepancy was attributed to unobserved transport of AP from the Central to the Eastern basin via nearshore currents past Long Point, while the NAP discrepancies were largely attributed to eastward movement of NAP through the lake within about 2 m of the lake bottom. The total amount of phosphorus retained within the lake in 1970 was 41,000 metric tons, or about 92% of input. AP of natural origin and inert nature accounted for approximately 44% of the total phosphorus retained. A reduction in anthropogenic phosphorus input of about 15,000 metric tons/yr, as called for in the Great Lakes Water Quality Agreement, will reduce present annual NAP loading to close to pre-1850 values.


1986 ◽  
Vol 43 (2) ◽  
pp. 379-388 ◽  
Author(s):  
Martin T. Auer ◽  
Mark S. Kieser ◽  
Raymond P. Canale

Two models for phosphorus and phytoplankton growth were field verified along a marked gradient in trophic conditions in Green Bay (Lake Michigan): one, the Monod model, relates growth rate to external (dissolved) phosphorus concentration, and the other, the Droop model, describes growth rate as a function of internal (stored) phosphorus levels. The verification provided through a satisfactory fit of model output to field measurements of phosphorus and gross photosynthesis established a conceptual foundation for empirical models relating phosphorus and trophic state parameters. Phosphorus concentrations corresponding to boundary conditions for trophic state categories were developed based on the verified models by defining oligotrophy as the region of linear response by growth rate to increases in phosphorus (<1.2 μg soluble reactive phosphorus (SRP)∙L−1, <11.5 μg total phosphorus (TP)∙L−1), mesotrophy as the transitional state (1.2–8.0 μg SRP∙L−1, 11.5–37.5 μg TP∙L−1), and eutrophy as the region where growth rate is saturated, i.e. insensitive to changes in phosphorus concentration (>8.0 μg SRP∙L−1, >37.5 μg TP∙L−1). We applied the trophic state classification scheme to several Great Lakes basins to examine their sensitivity to changes in phosphorus levels. The oligotrophic waters of Lakes Superior, Huron, and Michigan and northern Green Bay and Georgian Bay have the greatest sensitivity to increases in total phosphorus concentration. The eutrophic waters of southern Green Bay, western Lake Erie, and nearshore Lake Ontario are nutrient saturated and relatively insensitive to initial reductions in phosphorus levels. Offshore Lake Ontario, eastern and central Lake Erie, Saginaw Bay, and mid Green Bay lie in the transitional phase for sensitivity to phosphorus management.


1993 ◽  
Vol 50 (11) ◽  
pp. 2298-2304 ◽  
Author(s):  
R. Dermott ◽  
M. Munawar

Large populations of the exotic rounded (noncarinate) shelled mussel of the genus Dreissena were found to exist on soft sediments collected throughout the central and eastern basins of Lake Erie during July and August 1992. Two different phenotypes were present on fine sediments (<150 μm) in the eastern basin. An elongated white morph was common on the profundal sediments beyond 40 m depth, while the "quagga" mussel was common on sand and sandy silt at depths between 10 and 30 m. Together with the carinated zebra mussel Dreissena polymorpha, which is very abundant on hard substrates in the sublittoral region, at least 80% of Lake Erie's bottom sediments have been invaded by Dreissena. Only that region of the central basin (near Cleveland) which undergoes periodic summer anoxia was not inhabited by this genus.


2018 ◽  
Vol 75 (3) ◽  
pp. 488-496 ◽  
Author(s):  
Graham D. Raby ◽  
Christopher S. Vandergoot ◽  
Todd A. Hayden ◽  
Matthew D. Faust ◽  
Richard T. Kraus ◽  
...  

Thermoregulation is presumed to be a widespread determinant of behaviour in fishes, but has not often been investigated as a mechanism shaping long-distance migrations. We used acoustic telemetry and animal-borne thermal loggers to test the hypothesis that seasonal migration in adult walleye (Sander vitreus) in Lake Erie is size- and (or) sex-specific and related to behavioural thermoregulation. Female walleye migrated out of the warm, shallow western basin earlier than did males and were 1.8 times more likely to be detected on acoustic receivers in the deeper and cooler eastern basin. The few fish that remained in the western basin were restricted to a smaller range of higher temperatures (≥20 °C) than those that migrated to the central and eastern basins (∼16–21 °C). However, temperature records from walleye in the central basin were nearly indistinguishable from those in the eastern basin, suggesting thermal preferences alone could not explain migration to the eastern basin. As such, our effort to understand the mechanisms that cause migratory behaviours has generated mixed evidence on the role of temperature and that factors like foraging opportunities may have synergistic roles in the migration.


Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2567 ◽  
Author(s):  
Jolita Petkuviene ◽  
Diana Vaiciute ◽  
Marija Katarzyte ◽  
Iveta Gecaite ◽  
Giorgio Rossato ◽  
...  

Aquatic birds may impact shallow ecosystems via organic and nutrient enrichment with feces. Such input may alleviate nutrient limitation, unbalance their ecological stoichiometry, and stimulate primary production. Herbivorous and piscivorous birds may produce different effects on aquatic ecosystems due to different physiology, diet and feces elemental composition. We analyze the effects of droppings from swans (herbivorous) and cormorants (piscivorous) on phytoplankton growth via a laboratory experiment. These birds are well represented in the Curonian Lagoon, where they form large colonies. As this lagoon displays summer algal hyper-blooms, we hypothesize an active, direct role of birds via defecation on algal growth. Short-term incubations of phytoplankton under low and high feces addition produces different stimulation of algal growth, significantly higher with high inputs of cormorant feces. The latter produces a major effect on reactive phosphorus concentration that augments significantly, as compared to treatments with swan feces, and determines an unbalanced, N-limited stoichiometry along with the duration of the experiment. During the incubation period, the dominant algal groups switch from blue-green to green algae, but such switch is independent of the level of feces input and from their origin. Heterotrophic bacteria also are stimulated by feces addition, but their increase is transient.


1990 ◽  
Vol 47 (7) ◽  
pp. 1434-1445 ◽  
Author(s):  
T. G. Dunstall ◽  
J. C. H. Carter ◽  
B. P. Monroe ◽  
G. T. Haymes ◽  
R. R. Weiler ◽  
...  

Storms and upwellings resulted in significant alterations to the aquatic environment in the Long Point Bay region of Lake Erie, contributing to short-term variability in water chemistry and plankton. Both storms and upwellings resulted in nutrient enrichment (filtered reactive phosphorus, total inorganic nitrogen, reactive silicates and organic nitrogen) in lake surface waters during the period of lake warming, prior to mid-August. Storms and upwellings also differentially affected the distributions of specific zooplankton taxa in the lake surface stratum. The most prominent effect was the increased abundance of Diacyclops bicuspidatus thomasi during upwellings, particularly towards shore. The once-through cooling process of the generating station also affected zooplankton distributions, most notably that of D. bicuspidatus thomasi, with a nearshore increase in abundance that was similar to the influence exerted by upwelling.


1982 ◽  
Vol 39 (5) ◽  
pp. 748-759 ◽  
Author(s):  
J. Bloesch

From June through October 1978 sediment traps were moored at three stations in an inshore–offshore transect in the Eastern Basin of Lake Erie. Settling fluxes measured with the traps exposed close to lake bottom were rather similar at all three stations during summer stratification, averaging 6.1 g∙m−2∙d−1 for dry weight, 293 mg∙m−2∙d−1 for particulate organic carbon (POC), 38 mg∙m−2∙d−1 for particulate nitrogen (PN), and 5.44 mg∙m−2∙d−1 for particulate phosphorus (PP). A comparison of the hypolimnetic traps with the epilimnetic traps at the offshore station indicated that considerable resuspension takes place even in summer. During fall, however, the nearshore sedimentation rates were markedly increased because of storm-induced bottom resuspension. By comparing the trap catches with sediment cores taken at all three stations, a resuspension model for dry weight, POC, and PN was developed. The calculations showed that newly formed organic material is resuspended and redeposited more frequently at nearshore locations than offshore. This repeated nearshore resuspension enhances decomposition of detritus, as shown by low relative phytoplankton activity in the hypolimnetic traps, and results in horizontal transport of fine-grained organic matter in the offshore direction. The significant POC and PN concentration differences found in the inshore–offshore transect of the bottom sediments can be explained by these two processes.Key words: sedimentation, sediment traps, sediment cores, resuspension, inshore–offshore differences


2007 ◽  
Vol 4 (4) ◽  
pp. 433-454 ◽  
Author(s):  
M. Schartau ◽  
A. Engel ◽  
J. Schröter ◽  
S. Thoms ◽  
C. Völker ◽  
...  

Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved polysaccharides (PCHO). The exudation of PCHO is linked to an excessive uptake of DIC that is not directly quantifiable from utilisation of dissolved inorganic nitrogen (DIN), called carbon overconsumption. Given these conditions, the concept of assuming a constant stoichiometric carbon-to-nitrogen (C:N) ratio for estimating new production of POC from DIN uptake becomes inappropriate. Here, a model of carbon overconsumption is analysed, combining phytoplankton growth with TEPC formation. The model describes two modes of carbon overconsumption. The first mode is associated with DOC exudation during phytoplankton biomass accumulation. The second mode is decoupled from algal growth, but leads to a continuous rise in POC while particulate organic nitrogen (PON) remains constant. While including PCHO coagulation, the model goes beyond a purely physiological explanation of building up carbon rich particulate organic matter (POM). The model is validated against observations from a mesocosm study. Maximum likelihood estimates of model parameters, such as nitrogen- and carbon loss rates of phytoplankton, are determined. The optimisation yields results with higher rates for carbon exudation than for the loss of organic nitrogen. It also suggests that the PCHO fraction of exuded DOC was 63±20% during the mesocosm experiment. Optimal estimates are obtained for coagulation kernels for PCHO transformation into TEPC. Model state estimates are consistent with observations, where 30% of the POC increase was attributed to TEPC formation. The proposed model is of low complexity and is applicable for large-scale biogeochemical simulations.


1969 ◽  
Vol 26 (7) ◽  
pp. 1877-1888 ◽  
Author(s):  
David R. Wolfert

Of 2427 walleyes (Stizostedion vitreum vitreum (Mitchill)) examined from Lake Erie in 1964–66, no females were mature at ages below III and all were mature at age V. All male walleyes from the eastern basin were mature at age II, and those from the western basin at age III. Females from the western basin matured at a shorter length and a younger age than those from the eastern basin. Males from the western basin, on the other hand, matured at a longer length and greater age than those from the eastern basin.Egg production, which was estimated for 60 walleyes from the eastern basin and 78 from the western basin, ranged from 48,000 to 614,000. The number of eggs increased rapidly with increase in total length, but the relation between fecundity and weight was almost linear. Walleyes from the western basin were much more fecund for any given length, weight, or age than those from the eastern basin. Weight was the most accurate indicator of fecundity. The mean diameter of eggs from 32 ripe walleyes was 1.72 mm. Little relation existed between egg diameter and length or age of fish.


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