Formation of Alewife Concretions in Polluted Onondaga Lake

The previously reported finding of alewife concretions along the shores of Onondaga Lake in Upstate New York prompted investigation of the field conditions necessary for their formation and laboratory simulation of these conditions to induce concretion formation. Onondaga Lake is shown to be calcium-polluted and continuously supersaturated with respect to CaC03• Anaerobic conditions exist in the hypolimnion in approximately eight months of every year. In controlled laboratory experiments, formation of structure-retaining alewife concretions was successful under anaerobic conditions, and was enhanced by elevated calcium concentrations. Additional chemical analyses of fresh alewives, natural concretions and laboratory-formed concretions were performed. A previously proposed mechanism for concretion formation is evaluated with respect to the presented results. The common occurrence of alewife concretions in Onondaga Lake is a manifestation of the unique polluted state of the ecosystem, combined with the invasion of the lipid-rich alewife

Light scattering and Secchi depth in an oligotrophic lake: Insights from an individual particle analysis technique

Light-scattering attributes of particles of the upper waters of oligotrophic Skaneateles Lake, New York, were characterized monthly for the spring – fall interval of 2 years with scanning electron microscopy interfaced with automated image and X-ray analyses (SAX). SAX results were used to make forward estimates of the particulate scattering coefficients associated with 2 components (bx) of the overall particle population, minerogenic particles (bm) and diatoms (bdi), through Mie theory calculations. Estimates of the third component, scattering by organic particles other than diatoms (bo/nd), were calculated as the residual of bulk measurements of the particulate scattering coefficient (bp) and the summation of bm and bdi. Regulation of Secchi depth (SD) in the lake by bp was documented, in the form of a strong (R2 = 0.73) linear SD-1 – bp relationship. Variations in the summation (bm + bdi) explained 66% of the dynamics of bp and 56% for SD-1. A 2-component partitioning of bp that incorporates the SAX-Mie-based values of bm, and estimates of the contribution of all organic particulates with an empirical chlorophyll-a-based bio-optical model, failed to predict the bp dynamics but closed well on average for the entire study period. The SD-1 – bp relationship and the reported partitioning of bp were used to predict: (1) changes in bx from the study conditions that are consistent with a robust range of historic observations of SD, and (2) scenarios of management interest of levels of SD expected from hypothetical changes in bx

Quantifications and water quality implications of minerogenic particles in Cayuga Lake, New York, and its tributaries

An individual particle analysis technique, scanning electron microscopy interfaced with automated image and X-ray analyses (SAX), was applied to characterize the minerogenic particle populations of Cayuga Lake (New York) and its primary tributaries and quantify their effects on common water quality metrics. The primary summary metric of SAX results is demonstrated to be the total projected area of minerogenic particles per unit volume of water (PAVm). PAVm is documented to be linearly related to the minerogenic components of particulate phosphorus (PPm), turbidity (Tn/m), and the light scattering coefficient, and inversely related to Secchi depth (SD). SAX is demonstrated to support partitioning of PAVm into contributions of multiple size and geochemical classes. Clay mineral particles dominated in the tributaries and the lake, although they shifted somewhat to smaller sizes (1–15 µm) in the lake. Levels of PAVm were higher in a lake area that adjoins the tributary inputs than in pelagic waters, particularly after runoff events. This increased PAVm degraded water quality, including higher PPm and Tn/m and lower SD relative to the pelagic waters, although diminished (still recognizable) signatures are documented lake-wide. Advantages of SAX over gravimetric analyses for the minerogenic particle populations of lakes include (1) improved analytical performance, (2) insights from the more robust size and composition information, (3) theoretical advantages for optical impacts, and (4) stronger relationships with water quality metrics

Phytoplankton absorption and the chlorophyll a–specific absorption coefficient in dynamic Onondaga Lake

Phytoplankton absorption and its dependence on the concentration of chlorophyll a (Chl-a), as represented by the Chl-a–specific absorption coefficient (a*φ(λ)), is important to support models of growth and for bio-optical remote sensing algorithms to retrieve Chl-a. The dynamics of the phytoplankton absorption coefficient (aφ(λ)) and a*φ(λ), and their dependencies on Chl-a, are described for Onondaga Lake, New York, over a 6-year period for which major changes in trophic state, Chl-a, and community composition occurred. Strong positive dependencies of aφ(λ) on Chl-a are reported for absorption peaks in both the blue and red spectral regions that are qualitatively similar to relationships for ocean waters but differ quantitatively. Average values of a*φ at wavelengths of 440 and 676 nm were 0.0347 and 0.0171 m2 mg−1, respectively, with coefficients of variation of 37 and 31%. Significant negative relationships between a*φ and Chl-a were observed for blue and green wavelengths that were qualitatively consistent with the influences of pigment packaging and the contribution of accessory pigments to absorption. The operation of these influences is demonstrated through various forms of data analysis that resolved the following significant relationships: (1) negative dependence of the ratio aφ(440):aφ(676) on Chl-a; (2) flattening of aφ spectra in the blue and increases at the red maximum, with increases in Chl-a; and (3) negative dependence of aφ(490):aφ(676) on Chl-a. Values of a*φ(440) and a*φ(676) obtained for Onondaga Lake are considered in the context of the limited population reported for other inland waters and selected marine systems

Comparitive Metagenomics of Toxic Freshwater Cyanobacteria Bloom Communities on Two Continents

Abstract Toxic cyanobacterial blooms have persisted in freshwater systems around the world for centuries and appear to be globally increasing in frequency and severity. Toxins produced by bloom-associated cyanobacteria can have drastic impacts on the ecosystem and surrounding communities, and bloom biomass can disrupt aquatic food webs and act as a driver for hypoxia. Little is currently known regarding the genomic content of the Microcystis strains that form blooms or the companion heterotrophic community associated with bloom events. To address these issues, we examined the bloom-associated microbial communities in single samples from Lake Erie (North America), Lake Tai (Taihu, China), and Grand Lakes St. Marys (OH, USA) using comparative metagenomics. Together the Cyanobacteria and Proteobacteriacomprised \u3e90% of each bloom bacterial community sample, although the dominant phylum varied between systems. Relative to the existing Microcystis aeruginosa NIES 843 genome, sequences from Lake Erie and Taihu revealed a number of metagenomic islands that were absent in the environmental samples. Moreover, despite variation in the phylogenetic assignments of bloom-associated organisms, the functional potential of bloom members remained relatively constant between systems. This pattern was particularly noticeable in the genomic contribution of nitrogen assimilation genes. In Taihu, the genetic elements associated with the assimilation and metabolism of nitrogen were predominantly associated withProteobacteria, while these functions in the North American lakes were primarily contributed to by the Cyanobacteria. Our observations build on an emerging body of metagenomic surveys describing the functional potential of microbial communities as more highly conserved than that of their phylogenetic makeup within natural systems

Linking CDOM patterns in Cayuga Lake, New York, USA, to terrigenous inputs

Lacustrine patterns of the light absorption of colored dissolved organic matter (aCDOM) and its composition proxies were resolved and linked to concurrent conditions of tributary inputs for Cayuga Lake, New York. We analyzed fixed-frequency samples of the lake at 3 sites and runoff event-based samples at the mouths of 3 gauged tributaries over a 7 month interval and measured dissolved organic carbon (DOC) and aCDOM over the visible wavelengths (400–700 nm) and at 254 nm. The tributaries are demonstrated to be enriched in aCDOM and DOC, with widely different proxy conditions compared to the lake, which further diverge during runoff events. DOC, aCDOM, and the composition proxies for the tributaries had significant, and mostly strong, dependencies on flow rate, described by power-law relationships. The differences in the composition proxies indicated lower contributions of CDOM to the DOC pool, reduced aromaticity, decreased molecular size of CDOM, and decreased amounts of humic versus fulvic acids in the lake compared to the tributaries, all accepted signatures of photobleaching. Dynamics of aCDOM in the upper waters of the lake depended primarily on composition (e.g., color quality) and secondarily on a quantity metric (DOC), as demonstrated in a 2-component linear least-squares regression format. Signatures of linkages between the terrestrial inputs and in-lake aCDOM patterns and the effects of photobleaching include (1) the preferential in-lake loss of aCDOM relative to DOC, estimated from budget calculations; (2) the intermediate characteristics resolved at a near-shore site adjoining multiple tributary inflows; and (3) the magnitude and character of the dynamics observed at the pelagic sites

Trophic state responses of Onondaga Lake, New York to reductions in phopshorus loading from advanced wastewater treatment

This study evaluated the response of previously culturally hypereutrophic Onondaga Lake, New York, to major reductions in phosphorus (P) loading from a municipal wastewater treatment plant achieved over a 35-year period. Analysis of the response was based on long-term monitoring of effluent total P concentration (TPMetro) and a robust array of in-lake metrics of trophic state, including (1) TP, (2) chlorophyll a (Chl-a), (3) Secchi disk depth, (4) areal hypolimnetic oxygen deficit (AHOD), (5) the downward flux of volatile suspended solids, and (6) the minimum dissolved oxygen concentration in the upper waters during fall turnover. Substantial positive responses, which were significantly linearly related to the decreases in TPMetro, were documented for all of the metrics over the monitoring period. For example, a 91% reduction in TPMetro resulted in reductions of 84% and 59% in Chl-a and AHOD, respectively. The changes depict a transformation from hypereutrophy to upper mesotrophy, with the exception of AHOD values that remain in the eutrophic range. The delayed response of AHOD reflects slower sediment diagenesis processes. The relationships among the metrics of trophic state are considered in the context of literature expressions, accepted paradigms, and limitations related to variations in food web effects. Empirical models that include the effects of multiple drivers on interannual variations in contemporary trophic state metrics were developed and applied to forecast variability under existing conditions. This case study contributes to the scientific literature describing lake rehabilitation through reductions in P loading

Partitioning the contributions of minerogenic particles and bioseston to particulate phosphorus and turbidity

Protocols to partition the contributions of bioseston and minerogenic particles to turbidity (Tn) and particulate phosphorus (PP), as described by summations of the 2 components, are developed, tested, and applied. The analysis is based on coincident observations of Tn, PP, chlorophyll a (Chl), and the summation of the projected areas of individual minerogenic particles per unit volume (PAVm) for the wide variations encountered in time and between near-shore and pelagic sites over an 8-year study of Cayuga Lake, New York. PAVm was determined from an individual particle analysis technique, scanning electron microscopy interfaced with automated image, and X-ray analyses (SAX). The partitionings are based on a stoichiometric approach that adopts Chl and PAVm as the metrics of bioseston and minerogenic particles, respectively, and estimates developed here for stoichiometric ratios that relate Tn and PP to these 2 components. The systematically higher Tn and PP levels at the near-shore site, particularly following runoff events, are demonstrated to be a result of elevated PAVm associated with allochthonous inputs. A reasonably good match of the partitioned 2-component summations with bulk observations is reported. Application of the 2-component PP model establishes minerogenic particles made, on average, noteworthy (~10%) to substantial (≥20%) contributions to PP. The minerogenic particle component of PP was largely responsible for the greater summer average total phosphorus (TP) concentrations at the near-shore versus the pelagic site, the interannual variations in the differences between these sites, and exceedance of the TP water quality limit at the near-shore site. Minerogenic particles were the dominant component of Tn, a finding that is demonstrated to be consistent with optical theory, based on the much greater efficiency of side-scattering for minerogenic versus organic particles

Testing and application of a two-dimensional hydrothermal/transport model for a long, deep, and narrow lake with moderate Burger number

Setup, testing, and application of a 2-dimensional longitudinal–vertical hydrothermal/transport model (the transport submodel of CE-QUAL-W2) was documented for Cayuga Lake, New York, where the Rossby radius is on the order of the lake’s width. The model was supported by long-term monitoring of meteorological and hydrologic drivers and calibrated and validated using in-lake temperature measurements made at multiple temporal and spatial scales over 16 years. Measurements included (1) temperature profiles at multiple lake sites for 10 years, (2) near-surface temperatures at one end of the lake for 16 years, (3) high frequency temperature at multiple depths for 2 years, and (4) seasonal measurements of a conservative passive tracer. Seiche activity imparted prominent signatures within these measurements. The model demonstrated excellent temporal stability, maintaining good performance in uninterrupted simulations over a period of 15 years. Performance was improved when modeling was supported by on-lake versus land-based meteorological measurements. The validated model was applied through numeric tracer experiments to evaluate various features of transport of interest to water quality issues for the lake, including (1) residence times of stream inputs within the entire lake and a smaller region defined bathymetrically as a shallow shelf, (2) transport and fate of negatively buoyant streams, and (3) the extent of transport from the hypolimnion to the epilimnion. This hydrothermal/transport model is appropriate to serve as the transport submodel for a forthcoming water quality model for this lake and for other high aspect (length to width) ratio lacustrine systems for which the internal Burger number is order one or greater

Calibration and application of a sediment accumulation rate model – a case study

A mechanistic mass balance model for sediment accumulation rate (SAR) that accommodates the dry density and burial velocity of solids and the depth dependency of porosity was tested and applied to Onondaga Lake, New York, for a 130-year period. The modeling for this case study is supported by a rich history of multiple anthropogenic drivers and coupled date horizons from the paleolimnological record, characterization of physical attributes of the sediments, and long-term monitoring of the water column and lake inputs. The consistency of predictions of SAR and measurements of downward flux of suspended particulate material (DFSPM) from a long-term sediment trap program was also evaluated. The model was demonstrated to perform well in simulating the lake’s history of SAR, which was supported by 10 different depth–date horizons. This history for 100 years was regulated by the production of soda-ash at an adjoining industry, which enhanced autochthonous formation and deposition of calcium carbonate (CaCO3), proportional to the level of production of this chemical. The SAR was extraordinarily high (~5 kg m-2 yr-1) during the 40 years of peak soda-ash production. An abrupt, more than 2-fold decrease in SAR occurred when the industry closed. The contemporary SAR remains relatively high as a result of multiple drivers but is serving to enhance burial of contaminants, including mercury, as part of an ongoing rehabilitation program. A high level of consistency (within 30%) between the contemporary SAR and an annual estimate of DFSPM was documented. The utility of the model was demonstrated through applications that depict the amount of deposits contributed by the industry, the effect of compaction on burial velocity, the dilution effect of the high SAR values on the paleolimnological record, and the resolution of sediment diagenesis kinetics