Brachionus leydigii (Monogononta: Ploima) reported from the western basin of Lake Erie

Several species of non-indigenous planktonic invertebrates have historically been introduced to the Laurentian Great Lakes. Previous introductions of non-indigenous planktonic invertebrates to the Great Lakes have been crustacean zooplankton, specifically Cladocera and Copepoda. This report documents the first known occurrence of Brachionus leydigii var. tridentatus (Zernov, 1901) in Lake Erie and possibly the first detection of a non-indigenous rotifer species in the Laurentian Great Lakes. The specimen was collected from a U.S. EPA monitoring station in the western basin of Lake Erie on April 4, 2016.     

Current state of the sponge fauna (Porifera: Lubomirskiidae) of Lake Baikal: Sponge disease and the problem of conservation of diversity

The spatial distribution of healthy and diseased sponges in Lake Baikal was investigated. The endemic sponges were studied in May ? June 2015 at 11 transects within the depth range of 0 to 40 m. More than 500 sponge specimens were collected, and 29 taxa including 12 species and 17 morphospecies (sp. taxa) were identified. Among the 29 taxa, only B. martinsoni specimens and 14 morphospecies were healthy, whereas specimens of the other 11 species and 3 morphospecies were diseased, making up 35% of the total number of specimens (512). The different body forms of sponge found among the specimens were encrusting (66%), globulous (21%), and branched (13%). Sponges with necrosis signs, discolored specimens or covered with violet film or brown spots, were found in all transects under study (37 stations of 68). The percent cover of the bottom (per m²) by various body forms of sponges was evaluated with a sponge faunal state assessment test. Changes in the diversity and abundance of sponges due to their disease may jeopardize the functioning of the entire ecosystem of Lake Baikal which is a World Heritage Site. This baseline data on patterns of sponges, including their spatial distribution and percent cover, will be utilized to support future management and monitoring of Lake Baikal. Data on the current state of Baikal endemic sponge fauna are essential for understanding the causes and prognosis of disease processes of freshwater sponges.     

Fractioning of petroleum hydrocarbons from seeped oil as a factor of purity preservation of water in Lake Baikal (Russia)

Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were found in five different types of oil-containing samples emanating from deep oil seeps in Lake Baikal, the deepest and oldest lake in the world containing 20% of the world’s surface freshwater. The n-alkanes were the dominant component of the seeped oil on the water surface. PAHs were minor compounds of the oil, but this group is included in a priority series of organic contaminants that are subject to environmental regulation. The set of studied samples from the seep included: (i) freshly-emitted oil on the lake surface, (ii) oil at the lake bottom, (iii) samples of asphalt towers at the lake bottom, (iv) oil from voids within the sediment core and (v) samples of water from different depths. High variability in the concentrations of n-alkanes and PAHs suggested the presence of oil fractionation at the sediment-water interface. A light fraction of oil enriched by n-alkanes migrates to the surface of the lake’s water column, where n-alkanes are biodegraded by the Baikal microbial community while heavy oil fractions remain at the lake bottom and form asphalt towers in which PAHs with maximum toxicity accumulate. In the lake’s photic water layer, PAHs from light oil can be accumulated by phytoplankton. In the lake’s water column, benzo[a]pyrene was not detected over their detection limit (0.1 ng/L). The Toxic Equivalent (TEQ) value of PAHs identified in the Baikal water ranged from 0.001 to 0.012 ng/L.     

A mesocosm investigation of the effects of quagga mussels (Dreissena rostriformis bugensis) on Lake Michigan zooplankton assemblages

Dreissenid mussels are known to disrupt the base of the food web by filter feeding on phytoplankton; however, they may also directly ingest zooplankton thereby complicating their effects on plankton communities. The objective of this study was to quantify the effects of quagga mussel feeding on the composition and size structure of Lake Michigan zooplankton assemblages. Two mesocosm (six 946 L tanks) experiments were conducted in summer 2013, using quagga mussels and zooplankton collected near Beaver Island, MI, to examine the response of zooplankton communities to the presence and absence of mussels (experiment 1) and varying mussel density (experiment 2). Mesocosms were sampled daily and zooplankton taxa were enumerated and sized using microscopy and FlowCAM® imaging. In experiment 1, the presence of quagga mussels had a rapid negative effect on veliger and copepod nauplii abundance, and a delayed negative effect on rotifer abundance. In experiment 2, mussel density had a negative effect on veliger, nauplii, and copepodite abundance within 24 h. Multivariate analyses revealed a change in zooplankton community composition with increasing mussel density. Ten zooplankton taxa decreased in abundance and frequency as quagga mussel density increased: except for the rotifer Trichocerca sp., treatments with higher mussel densities (i.e., 1327, 3585, and 5389 mussels/m²) had the greatest negative effect on small-bodied zooplankton (≤ 128 μm). This study confirms results from small-scale (≤ 1 L) experiments and demonstrates that quagga mussels can alter zooplankton communities at mesoscales (~ 1000 L), possibly through a combination of direct consumption and resource depletion.     

Groundwater contamination by sewage causes benthic algal outbreaks in the littoral zone of Lake Baikal (East Siberia)

Lake Baikal, an ancient lake in Siberia, contains more endemic species than any other lake in the world with most of them residing in the benthic littoral zone. Explosive growth of benthic Spirogyra, a filamentous green alga, began approximately in 2011 in localized coastal areas, with the most severe examples occurring near coastal towns that lack a wastewater treatment facility or have a malfunctioning system. At other sites (small settlements, harbors), however, the cause of its excess growth is less obvious. Multiple hypotheses have been offered including lake level fluctuations, climate warming, a relaxation of grazing pressure, and coastal eutrophication. We assessed these hypotheses using data on historical lake levels, water temperature, the spatial-temporal distribution of Spirogyra along inhabited and non-inhabited shorelines, and measurements of fecal coliform bacteria and nutrients in ground water, interstitial water, and lake water. These data suggest that groundwater contamination is the primary cause of coastal eutrophication. Most houses and buildings in small settlements around Lake Baikal lack septic tanks but use unlined cesspools to collect human waste. This untreated human waste enters groundwater via passive filtration through permeable soils and flows to the coastal zone where it drives excess growth of Spirogyra. Remediation — including installation of septic systems, modernization of existing sewage treatment plants in coastal towns, and the adoption of non-phosphate containing detergents — as well as a reconsideration of the federal monitoring system regarding the coastal zone is urgently needed to protect this extraordinary lake.     

Bathymetric distribution of chironomid larvae (Diptera: Chironomidae) in Lake Saiko,Japan

The distribution of benthic macroinvertebrate on 8 March 2009 was studied in Lake Saiko (73.2 m maximum depth). The average density of the benthic community for the entire lake was 19 583 individuals m^?2, being comprised of oligochaetes and chironomid larvae, with densities of 18 163 (92.8%) and 1274 (6.5%), respectively. The average wet weights of oligochaetes and chironomid larvae were 15.96 and 1.67 g m^?2, respectively. The oligochaetes inhabited the entire lake bottom, with their densities being higher in the transitional region (20–40 m) and deeper region (>40 m) than in the shallower region. However, the densities of chironomid larvae were low in the deeper region (>40 m), with only a few chironomid larvae being found in the centre of the lake (>60 m). The most abundant species (Micropsectra chuzeprima) exhibited the widest distribution (from 10.1 to 65.5 m depth), followed by Polypedilum nubeculosum. The results of this study also were compared to previous data on oligochaetes and chironomid larvae reported by Kitagawa (1973) . The density of these animals increased throughout the whole lake in 2009. However, the chironomid species compositions did not changed. The larval distribution pattern of chironomid changed since Kitagawa’s study, being distributed from 11 to 68 m in 1973. In contrast, almost all chironomid larvae were found in the transitional (e.g. M. chuzeprima) and shallower (e.g. Procladius choreus and P. nubeculosum) regions in 2009, with only a few individuals being observed in the deeper regions (>60 m). In contrast, the oligochaete density increased in the deeper regions. Large environmental changes must have affected the oligochaetes and chironomids densities, especially in the deeper regions with low dissolved oxygen concentrations. Consequently, the distribution pattern of oligochaetes and chironomids in the lake has changed. These study findings suggest the lake is experiencing increasing eutrophication.     

Fall diet and bathymetric distribution of deepwater sculpin (Myoxocephalus thompsonii) in Lake Huron

Deepwater sculpin Myoxocephalus thompsonii are an important component of Great Lake's offshore benthic food webs. Recent declines in deepwater sculpin abundance and changes in bathymetric distribution may be associated with changes in the deepwater food web of Lake Huron, particularly, decreased abundance of benthic invertebrates such as Diporeia. To assess how deepwater sculpins have responded to recent changes, we examined a fifteen-year time series of spatial and temporal patterns in abundance as well as the diets of fish collected in bottom trawls during fall of 2003, 2004, and 2005. During 1992–2007, deepwater sculpin abundance declined on a lake-wide scale but the decline in abundance at shallower depths and in the southern portion of Lake Huron was more pronounced. Of the 534 fish examined for diet analysis, 97% had food in the stomach. Mysis, Diporeia, and Chironomidae were consumed frequently, while sphaerid clams, ostracods, fish eggs, and small fish were found in only low numbers. We found an inverse relationship between prevalence of Mysis and Diporeia in diets that reflected geographic and temporal trends in abundance of these invertebrates in Lake Huron. Because deepwater sculpins are an important trophic link in offshore benthic food webs, declines in population abundance and changes in distribution may cascade throughout the food web and impede fish community restoration goals.     

Incorporation of non-native species in the diets of cisco (Coregonus artedi) from eastern Lake Ontario

Cisco Coregonus artedi was once an important native fish in Lake Ontario; however, after multiple population crashes, the cisco stock has yet to recover to historic abundances. Rehabilitation of cisco in Lake Ontario is a fish community management objective, but the extent to which recent non-native species and pelagic food web changes have influenced cisco is not well understood. We described cisco diets in contemporary Lake Ontario following the addition and spread of non-native zooplankton species. We collected 618 cisco and processed 178 for full diet analysis in eastern Lake Ontario using mid-water trawls and bottom-set gill nets from 2016 to 2020. We found that Lake Ontario cisco were mostly zooplanktivorous, and non-native zooplankton dominated their diet during July and September. Cisco smaller than 300 mm had a more diverse diet including both native and non-native zooplankton, while cisco larger than 300 mm fed almost exclusively on non-native predatory cladocerans Bythotrephes longimanus and Cercopagis pengoi (98.9% consumed prey dry mass). We also found fish eggs, presumed to be of coregonine origin in 75% of non-empty December-collected cisco diets, suggesting eggs subsidize cisco diets when available. Juvenile round goby Neogobius melanostomus, alewife Alosa pseudoharengus and rainbow smelt Osmerus mordax were found in 2% of all analyzed non-empty stomachs. Lake Ontario cisco diet appears to be more similar to zooplanktivorous Lake Superior cisco than Lake Michigan where piscivory is prevalent. Lake Ontario cisco diets reflected zooplankton community changes indicating that non-native predatory cladocerans are now an important energy source supporting this native species.     

Evaluation of pharmaceuticals and personal care products (PPCPs) in drinking water originating from Lake Erie

This project evaluated pharmaceuticals and personal care products (PPCPs) concentrations in drinking water originating from Lake Erie. Raw and treated water samples were collected from the local water treatment plant in Erie, Pennsylvania over a 10 month period. Along with grab samples, long-term samples were collected using Polar Organic Chemical Integrative Samplers (POCIS). The samples were analyzed for 17 PPCPs (acetaminophen, ampicillin, atrazine, bisphenol-A, caffeine, carbamazepine, cimetidine, ciprofloxacin, digoxin, gemfibrozil, ibuprofen, metformin, naproxen, simazine, sulfamethoxazole, sulfathiazole, trimethoprim) in raw and treated drinking water. For grab samples, six of the 17 PPCPs were found at detectable levels in raw or treated drinking water including atrazine, bisphenol-A, caffeine, ibuprofen, metformin, and simazine. Detectable PPCP levels in treated water samples were usually lower than those in raw water. For long-term samples, an additional four PPCPs (ten total) were found at detectable levels including gemfibrozil, naproxen, sulfamethoxazole, and trimethoprim. Aqueous phase concentrations of PPCPs were estimated using sampling rates, deployment periods, and analytical results of POCIS samplers.     

Joint probability distribution of winds and waves from wave simulation of 20 years (1989-2008) in Bohai Bay

The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gumbel logistic model, the Gumbel-Hougaard (GH) copula function, and the Clayton copula function. Twenty years of wind data from 1989 to 2008 were collected from the European Centre for Medium-Range Weather Forecasts (ECMWF) database and the blended wind data of the Quick Scatterometer (QSCAT) satellite data set and re-analysis data from the United States National Centers for Environmental Prediction (NCEP). Several typhoons were taken into account and merged with the background wind fields from the ECMWF or QSCAT/NCEP database. The 20-year data of significant wave height were calculated with the unstructured-grid version of the third-generation wind wave model Simulating WAves Nearshore (SWAN) under extreme wind process conditions. The Gumbel distribution was used for univariate and marginal distributions. The distribution parameters were estimated with the method of L-moments. Based on the marginal distributions, the joint probability distributions, the associated return periods, and the conditional probability distributions were obtained. The GH copula function was found to be optimal according to the ordinary least squares (OLS) test. The results show that wind waves are the prevailing type of wave in the Bohai Bay.     

Phosphorus Nutrition of Two Potentially Competing Filamentous Algae, Cladophora Glomerata (L.) Kütz. and Stigeoclonium Tenue (Agardh) Kütz. from Lake Ontario

Cladophora glomerata and Stigeoclonium tenue were isolated from Lake Ontario. Batch culture growth experiments at 20° C and 175 μE/m²?sec continuous light show the maximum growth rate of Stigeoclonium (2.0 day^?1) to be about 2.5 times that of Cladophora (0.8 day^?1). The maximum phosphorus uptake rate for Stigeoclonium is 20 times greater than that for Cladophora and the half-saturation coefficient is larger by a factor of three. From growth experiments, the level of minimum cellular phosphorus of declining-phase cells is similar for both species but Stigeoclonium exhibits a greater luxury maximum level (in lag-phase cells) by a factor of over two. This, plus the fact that the growth rate of Stigeoclonium exceeds that of Cladophora at all levels of external and cellular phosphorus, allows Stigeoclonium to be more successful at phosphate-based competition. This is further confirmed by the facts that (compared to Stigeoclonium) the half-saturation growth constant is three times greater in Cladophora and the ratio of this constant to maximum growth rate is also eight times greater in Cladophora. It is hypothesized that the present-day dominance by Cladophora in the littoral region of the lower Great Lakes may not be determined by phosphate limitation but by certain competitive aspects of the life cycle, growth form, and physiology.     

Gut contents from multiple morphs of lake trout (Salvelinus namaycush) at two offshore shoals in Lake Superior

Four lake trout, Salvelinus namaycush, Walbaum 1792 morphs occur in Lake Superior: lean, siscowet, humper, and redfin. Diets of lean and siscowet have been relatively well described. However, less is known about diets of humper and redfin, and overall few studies have been conducted at offshore shoals. We compared gut content data among mature (357–867 mm) sympatric lake trout morphs caught at two offshore shoals in Lake Superior, Stannard Rock and Superior Shoal, in 2013 and 2014 (total n = 416). All morphs were caught in shallow (<50 m), mid (50–100 m), and deep (>100 m) strata. Invertebrates made up a greater portion of the stomach contents than did fish for all morphs by both percent occurrence and proportional biomass, and Mysis was the primary invertebrate consumed by all morphs at both sites. Coregonus spp. and deepwater sculpin, Myoxocephalus thompsonii were the most commonly consumed fish. Humper had the highest average proportional biomass of deepwater sculpin and had no other identifiable species of fish in their guts. Biomass of fish in redfin guts was highest for Coregonus spp., followed by similar amounts of deepwater sculpin and burbot, Lota lota. Diet overlap among morphs was high, and differences in prey consumption between sites are likely related to prey availability. Additional study is needed to determine if differences in trophic ecology between humper and other morphs are sufficient to support concurrent stocking of multiple morphs, particularly in light of recent declines in native prey fishes, especially Coregonus spp., in the Laurentian Great Lakes.     

Distinguishing Wild vs. Stocked Lake Trout (Salvelinus namaycush) in Lake Ontario: Evidence from Carbon and Oxygen Stable Isotope Values of Otoliths

We investigated the potential for using carbon and oxygen isotope values of otolith carbonate as a method to distinguish naturally produced (wild) lake trout (Salvelinus namaycush) from hatchery-reared lake trout in Lake Ontario. We determined δ ¹³C_(CaCO3) and δ ¹⁸O_(CaCO3) values of otoliths from juvenile fish taken from two hatcheries, and of otoliths from wild yearlings. Clear differences in isotope values were observed between the three groups. Subsequently we examined otoliths from large marked and unmarked fish captured in the lake, determining isotope values for regions of the otolith corresponding to the first year of life. Marked (i.e., stocked) fish showed isotope ratios similar to one of the hatchery groups, whereas unmarked fish, (wild fish or stocked fish that lost the mark) showed isotope ratios similar either to one of the hatchery groups or to the wild group. We interpret these data to suggest that carbon and oxygen isotope values can be used to determine the origin of lake trout in Lake Ontario, if a catalogue of characteristic isotope values from all candidate years and hatcheries is compiled.     

First data on lipids and microorganisms of deepwater endemic sponge Baikalospongia intermedia and sediments from hydrothermal discharge area of the Frolikha Bay (North Baikal,Siberia)

In this report, we study lipid components (fatty acids with various degrees of unsaturation, aldehydes and sterols) of deep-water sponges Baikalospongia intermedia and sediments sampled using deep-water manned submersibles “Mir” at a hydrothermal vent of Frolikha Bay at depths of 400–450 m. It was found that unsaturated fatty acids predominate in the FA-composition of the sponges: very long chain demospongic acid 26:3, as well as monounsaturated 24:1 and isomers of acids 16:1 and 18:1. Among the saturated fatty acids in addition to the stearic 18:0, palmitic 16:0 and heptadecanoic 17:0 acids, significant amounts of acids of microbial origin (iso-palmitic i16:0, isostearic i18:0, oxy-stearic 10 h18) were detected. Using the method of mass spectrometry of microbial markers, we conclude, that the main microbial components of sponges B. intermedia and sediments from Frolikha Bay are methanotrophic microorganisms.     

Effect of hypolimnetic discharge on the faster deprivation of phosphorus from lake sediment (Lake Jabel, north-east Germany)

After the reduction in external phosphorus‐load (P‐load), in‐lake measures became practicable for eutrophic Lake Jabel. The benthic release of phosphorus (P) was efficiently suppressed by a significant nitrate supply via its main tributary. The in‐situ stimulation of P‐release as a result of the temporary decrease in this nitrate load, and the simultaneous P‐removal by deep‐water siphoning and external P‐elimination was primarily designed for the faster deprivation of P from lake sediment. This new strategy was aimed at exhausting the ‘P‐surplus’, that is, the mobile redox‐sensitive iron‐bound P‐portions of the uppermost sediment layers, where a re‐supply from deeper layers is needed within the stratification period of 2 consecutive years of operation of the P‐elimination system. By studying early benthic P‐diagenesis it remains to be demonstrated whether this procedure can contribute to a re‐availability of P‐binding sites to guarantee the long‐term effect of the measure.     

Re-interpreting Great Lakes shorelines as components of wave-influenced deltas: An example from the Portage River delta (Lake Erie)

Deltas deliver both sediment (bedload sands and suspended load muds) and water to a coastal environment. In the past, deltaic models have emphasized the sandy bedload component constructing a depositional feature that protrudes from the coastline. In contrast, wave-influenced deltas form where river discharge effectively blocks the prevailing longshore drift. The resulting delta is asymmetric, with an extensive strandplain of multiple beach ridges updrift, and fewer beach ridges with wetlands, ponds, and subsidiary bay-head deltas downdrift. In Lake Erie, an analysis of 28 vibracores from the Portage River delta demonstrates significant updrift-downdrift sedimentological differences. Updrift of the delta consists of > 3 m thick gravel-rich sands overlying glaciolacustrine sediment. The deposits are organized into coarsening-upward, progradational shoreline sequences showing facies transitions from lower shoreface to upper shoreface to beachface to backbeach. A 1939 aerial photograph suggests > 15 prograding shoreline sequences were accreted during present lake levels (highstand systems tract), resulting in re-attachment of a bedrock high (Catawba Island) to the mainland. Downdrift of the delta consists of a one progradational shoreline sequence < 1 m thick that overlies peats and glaciolacustrine sediment. The peats have ¹⁴C ages between 1616 and 2025 cal YBP, and are interpreted as wetlands that formed during an earlier phase of rising lake levels (lowstand and transgressive systems tracts). The overlying beach ridge was accreted during present lake levels (highstand system tract). The coastal features in this portion of Lake Erie are best understood as components of an evolving wave-influenced delta, the first recognized in the Great Lakes.     

Temporal and spatial variability of PCB concentrations in lake trout (Salvelinus namaycush) in Lake Superior from 1995 to 2016

Production of polychlorinated biphenyl compounds (PCBs) was banned over 40 years ago in the United States and Canada, but they remain a dominant contaminant in Great Lakes fish. Although PCB concentrations in Great Lakes fish have declined since the 1980s, there is concern that the rate of decline has slowed in recent years. Canadian and U.S. national agencies monitor trends in fish contaminants at only a few sites in each lake, while states and provinces monitor fish at more locations. In this study, we compare fish PCB measurements made by five agencies at multiple locations in order to evaluate spatial as well as temporal patterns in Lake Superior. For several monitoring locations, rapid increases and decreases in concentrations were observed. The wide range of concentrations (up to 1000 ng/g) reported among all stations in any single year is unlikely to result solely from differences in fish preparation or analytical techniques. Recent measurements indicate that spatial variation in fish PCB concentrations exists with peak concentrations 30-fold higher than lowest concentrations. After 1995, statistically significant changes, all declines, in PCB concentrations were observed at only three of seven locations; half-lives in these locations ranged from 9 to 14 years. Differences in diet and food web structure likely contribute both to the spatial variability of concentrations within the lake as well as to the rapid, short-term changes in concentrations at single sites that make long-term trends difficult to discern and to predict.     

Non-seismic soft-sediment deformation structures from Late Pleistocene lacustrine deposits of Lake Van (Eastern Turkey): Storm and overloading effect

Soft-sediment deformation structures of different types and sizes are frequently observed in the lacustrine deposits of Lake Van. According to sedimentary features and regional factors, these structures are categorized as non-seismic originated and seismically-induced, soft-sediment deformation structures. Well-preserved non-seismic originated, soft-sediment deformation structures were observed in fine-grained sandy and silty deposits at three locations (Çatakdibi, Yumrutepe, and Yukar????kl?), and occur at different stratigraphic horizons, exhibiting morphological variability as they consist of load, flame, and slump structures. The formation mechanisms of these structures are determined by the characteristics of their sedimentary facies and environmental conditions. Overloading, caused by rapid coarse sediment deposition or underwater landslides, and storm waves are identified as triggering mechanisms, while rapid sediment accumulation and underwater mass movements caused by volcanogenic shakes are the conditions responsible for the formation of non-seismic soft-sediment deformation structures, in terms of regional geodynamics.     

The effect of tectonism on deltaic wetland migration: A case study from Bendimahi River Delta System (Lake Van-Eastern Turkey)

Coastal wetlands are in decline globally because of climatic and/or hydrological changes, and anthropogenic activities. Deltaic wetlands are complex environments formed by different water sources, particularly when ionically rich soda water and freshwater and converge and influence the presence and diversity of biological activity. Lake Van is a terminal lake, 1650 meters above the sea level, surrounded by high mountains. Because of its alkaline water, vegetation and biological activity are generally rich in the deltaic areas. In this study, geological evolution of Bendimahi River Delta System, located on northeastern part of the Lake Van, is assessed as to constructive and destructive temporal factors, determined with satellite images and field studies. Bendimahi river channel is significantly deformed by regional tectonic activity and this deformation has caused migration of deltaic wetland. That migration process has resulted in abandoned deltaic area and a new delta formation. Hydrological and biological results of the migration of the Bendimahi River Delta System clearly indicate the importance of wetlands on coastal ecology, especially alkaline lakes.     

Use of otolith chemistry to discriminate juvenile Chinook salmon (Oncorhynchus tshawytscha) from different wild populations and hatcheries in Lake Huron

Chinook salmon (Oncorhynchus tshawytscha) in Lake Huron consist of wild and hatchery-reared fish distributed among several populations. This study tested whether otolith chemistry can be used to identify the natal origin of Chinook salmon in this system. Concentrations of nine elements (Mg, K, Mn, Fe, Zn, Rb, Sr, Ba, and Pb) in the otoliths of Chinook salmon juveniles from 24 collection sites (17 streams and 7 hatcheries) around Lake Huron were analyzed using laser-ablation inductively-coupled mass spectrometry. Differences in otolith chemistry were found between rearing environments (wild and hatchery), among geological regions (Precambrian, Ordovician, Silurian, Devonian, and Carboniferous), and among collection sites. Discriminant function analysis showed high classification accuracies of juveniles to their rearing environment (wild versus hatchery, 82%), geological region (84%), and collection site (87%) of origin. With these values, there is excellent potential for otolith chemistry to be used to predict the natal origin of adults, and thus inform research and management of Chinook salmon in Lake Huron.