Geology topics

Research about Green Bay, Lake Michigan

Source-linked reports with geographic coverage including Green Bay, Lake Michigan.

5 recordsLinked to original sources

USGS2025

Muskellunge spawning habitat characteristics and availability in Green Bay, Lake Michigan

Objective Habitat degradation has been associated with the loss of many self-sustaining Muskellunge Esox masquinongy populations, including those in Green Bay, where stocking has provided an exceptional trophy fishery but restoration goals include establishing self-sustaining populations and there is little evidence of natural recruitment. Our objectives were to determine whether (1) Muskellunge spawning locations and occurrence of successful hatching were related to a suite of habitat characteristics, (2) proportions of Muskellunge spawning in or outside of tributaries to lower Green Bay were different, and (3) Muskellunge showed spawning site fidelity. Methods From 2017 to 2019, adult Muskellunge ( N = 60) were surgically implanted with radio and acoustic transmitters to identify spawning locations, where we measured a suite of habitat variables and attempted to collect eggs and larvae. Side-scan sonar was used to quantify the amount of habitat available to Muskellunge for egg deposition in the Fox and Menominee rivers, which are tributaries to Green Bay. Results Muskellunge eggs were collected at 58 locations, but only two larvae were collected from a single location. Bottom slope, depth, distance to shore, gravel substrate, organic matter, and dissolved oxygen best predicted the presence of Muskellunge eggs. We determined that little habitat associated with Muskellunge egg deposition was available in the Fox and Menominee rivers. However, approximately half of tagged Muskellunge appeared to spawn outside of tributaries. Muskellunge in Green Bay displayed moderate spawning site fidelity. Conclusions Our results suggest that successful hatching occurs at very low levels and the lack of suitable Muskellunge spawning habitat in Green Bay tributaries may be limiting natural reproduction. Changes in spatial allocation of stocked fish and enhancement of known spawning locations may increase egg deposition and subsequent natural reproduction.

Michigan, Wisconsin↗

USGS2022

Diet composition and overlap for adult walleye, lake whitefish, and yellow perch in Green Bay, Lake Michigan

Interspecific interactions among walleye Sander vitreus , lake whitefish Coregonus clupeaformis , and yellow perch Perca flavescens in Green Bay could influence the population status of each species, but potential trophic interactions are poorly understood. Our objectives were to determine if diet assemblages for each species and diet overlap among species varied spatially and temporally within Green Bay. Adult walleye (≥ 381 mm total length (TL); N = 981), lake whitefish (≥ 432 mm TL; N = 1507), and yellow perch (≥ 150 mm TL; N = 1174) were collected during May-October of 2018 and 2019 from multiple locations in southern and northern Green Bay. Diet assemblages of all three species varied between zones but walleye diets were more temporally variable (among months within zones and between years) than diets of lake whitefish or yellow perch. Lake whitefish represented a seasonally important prey item for walleye in southern Green Bay, composing 10% and 41% of walleye diets by weight in May and June, respectively. Yellow perch generally composed < 15% of walleye diets by weight but were consumed at a broader spatiotemporal scale than lake whitefish. Diet overlap between walleye and both lake whitefish and yellow perch was generally weak or moderate, whereas diet overlap between whitefish and perch was generally strong. Our assessment of adult trophic interactions suggests that changes in the population status of one species could influence fisheries for all three, and we identify additional research questions to address potential population-level effects of these trophic interactions.

Wisconsin↗

USGS2018

Water column nutrient processing rates in rivermouths of Green Bay (Lake Michigan)

Understanding the quantity and form of nutrient loads to large lakes is necessary to understand controls over primary production, phytoplankton community composition and the production of phytotoxins. Nutrient loading estimates to large lakes are primarily made at stream gages that are deliberately placed outside the direct influence of lake processes, but these estimates cannot take into account processes that occur in the biologically active river-to-lake transition zone. These transition zones (rivermouths) sometimes alter nutrient concentrations and ratios substantially, but few studies have directly measured processing rates of nutrients within rivermouths. From April through September 2016, we conducted 23 water column incubation experiments to measure nutrient loss rates in four rivermouths. First order loss rates ( K ) for inorganic nitrogen (N) and phosphorus (P) indicated greater loss in light than in dark treatments, suggesting primary production increases N and P removal. Variability in K was high across both time and space, and the measured environmental parameters did not appear to be strongly associated with this variation in K for most N and P forms. If the measured K values and water residence times are accurate, then between 0 and 99% of the inorganic P and nitrates entering the rivermouth would be lost (i.e., converted to organic or particulate P). In late summer, Fox River discharge is low and residence times are usually long, which allow for much higher proportional nutrient removal in the water column. Water column processing appears to be capable of transforming large quantities of dissolved N and P to particulate forms and thus altering its transport and presumably its bioavailability.

Green Bay, Lake Michigan↗

USGS2011

Sedimentary phosphorus cycling and a phosphorus mass balance for the Green Bay (Lake Michigan) ecosystem

The tributaries of Green Bay have long been recognized as major sources of phosphorus in the Lake Michigan basin. The status of Green Bay as a sink or source of phosphorus for Lake Michigan proper has been less well defined. The bay receives nearly 70% of its annual load of phosphorus ( 700 metric tons (t) · year-1) from a single source: the Fox River. Most of this phosphorus is deposited in sediments accumulating at rates that reach 160 mg · cm-2 · year-1 with an average of 20 mg · cm-2 · year-1. The phosphorus content of these sediments varies from <5 to >70 µmol · g-1. Deposition is highly focused, with ~70% of the total sediment accumulation and at least 80% of the phosphorus burial occurring within 20% of the surface area of the bay. Diagenetic and stoichiometric models of phosphorus cycling imply that >80% of the phosphorus deposited is permanently buried. External phosphorus loading to the bay is combined with sediment fluxes of phophorus to arrive at a simple phosphorus budget. Green Bay acts as an efficient nutrient trap, with the sediments retaining an estimated 70-90% of the external phosphorus inputs before flowing into Lake Michigan.

Wisconsin↗

USGS1987

Embryotoxicity, teratogenicity, and aryl hydrocarbon hydroxylase activity in Forster's terns on Green Bay, Lake Michigan

Known reproductive problems, including congenital malformations and poor hatching success, exist for the state endangered Forster's tern ( Sterna forsteri ) in Green Bay, Wisconsin. Twenty Forster's tern eggs were collected from separate nests at (i) a natural colony with documented reproductive problems, situated at Green Bay, Lake Michigan, and (ii) an inland colony at Lake Poygan (control) where reproduction was documented as normal. Eggs from the two locations were placed in the same laboratory incubator and candled throughout incubation. Hatching success of Green Bay eggs was 52% of that for controls. Several early embryonic deaths occurred, but most mortality occurred close to the time of hatching. Liver microsomal aryl hydrocarbon hydroxylase activity was elevated approximately threefold in Green Bay hatchlings compared to controls. Green Bay terns that hatched weighed less than controls, had an increased liver to body weight ratio, and had a shorter femur length. Two Green Bay embryos that failed to hatch had anomalies, one with a crossed beak and one with poor ossification of the foot. One Green Bay hatchling had an abnormally ossified ilium. These effects were observed in eggs where there were measureable levels of aryl hydrocarbon hydroxylase inducers including polychlorinated biphenyls and polychlorinated dibenzo- p -dioxins.

Wisconsin↗