Lawrence W. Eichler

Loss of native aquatic plant species in a community dominated by Eurasian watermilfoil

Ecological evaluation of the impact of an exotic species upon native plant species is frequently a combination of historical data prior to introduction and after full establishment with little observation in between. The introduction of Myriophyllum spicatum L. (Eurasian watermilfoil) into Lake George, New York, U.S.A. was first noted in 1985. In 1987, a few newly established plants were allowed to grow unimpeded by human management to document the rate of colonization of this species into a new habitat with its ultimate dominance over, and systematic elimination of, native species. This changing community has been closely monitored over the past decade. Initially a 6 m2 grid system composed of 144 0.5 m2 plots with four radiating transect lines was laid out with the isolated M. spicatum plants as the center. The site was revisited between 1987 and 1997 to mark the extent of the developing M. spicatum bed and its effect on the composition of the native plant community. Since 1987, the area of dense growth has expanded in all directions, impeded only where some physical barrier, such as upper or lower water depth limits or sediment type curtailed its growth. Concurrently, with this expansion, a decline in species richness and abundance of native species was observed.

The Aquatic Macrophyte Community of Onondaga Lake: Field Survey and Plant Growth Bioassays of Lake Sediments

ABSTRACT Onondaga Lake, located in the Syracuse metropolitan area of upstate New York, has been heavily impacted by domestic and industrial waste effluents, resulting in a lake with high salinity, low light availability, and a highly calcareous, nutrient-poor sediment. These factors appear interrelated in reducing the cover, distribution and diversity of aquatic plants between 1940 and 1990. A quantitative survey in 1991 found that only 13% of the littoral zone had any aquatic plants. The plant community was dominated by Potamogeton pectinatus (11%), with four other submersed aquatic plants found: Ceratophyllum demersum, Heteranihera dubia, Myriophyllum spicatum, and Potamogeton crispus. Aquatic plants were found less often than expected on the calcium-carbonate oncolite sediments, which are formed from precipitated calcium carbonate, compared to other sediment types in the lake. Laboratory studies were developed to evaluate the role of sediments in limiting plant growth. These studies showed that Onondag...

Application of multivariate statistics in detecting temporal and spatial patterns of water chemistry in Lake George, New York

Cluster and component analyses were used to identify temporal and spatial patterns of water chemistry in Lake George, a meso-oligotrophic lake in northeastern New York, during 1981–1993. The lake includes two major basins that have similar area and volume, but different biological community structure, plankton assemblages, watershed area, and watershed development. Analyses were based on total phosphorus, particulate phosphorus, dissolved organic phosphorus, dissolved inorganic phosphorus, nitrate, calcium, chlorophyll a, silica, chloride, and pH, individually or in combinations. Total phosphorus, chlorophyll a, chloride, and particulate phosphorus were included in the first linear component indicating that these are probably the most important analytes in explaining the total variance of the data. In spring or summer, three or four components explained 86 or 84% of the total variance, respectively. Cluster analysis based on the major components or on the original variables indicated that there are distinct differences in water chemistry between the two major basins of the lake. The only long-term temporal pattern that could be detected by cluster analysis was an increase in chloride concentrations. Cluster analysis is found to be a useful tool to detect both step (abrupt) and monotonic (gradual) changes in time and space.

Acidification in the Adirondacks: Defining the Biota in Trophic Levels of 30 Chemically Diverse Acid-Impacted Lakes

The Adirondack Mountains in New York State have a varied surficial geology and chemically diverse surface waters that are among the most impacted by acid deposition in the U.S. No single Adirondack investigation has been comprehensive in defining the effects of acidification on species diversity, from bacteria through fish, essential for understanding the full impact of acidification on biota. Baseline midsummer chemistry and community composition are presented for a group of chemically diverse Adirondack lakes. Species richness of all trophic levels except bacteria is significantly correlated with lake acid-base chemistry. The loss of taxa observed per unit pH was similar: bacterial genera (2.50), bacterial classes (1.43), phytoplankton (3.97), rotifers (3.56), crustaceans (1.75), macrophytes (3.96), and fish (3.72). Specific pH criteria were applied to the communities to define and identify acid-tolerant (pH<5.0), acid-resistant (pH 5.0-5.6), and acid-sensitive (pH>5.6) species which could serve as indicators. Acid-tolerant and acid-sensitive categories are at end-points along the pH scale, significantly different at P<0.05; the acid-resistant category is the range of pH between these end-points, where community changes continually occur as the ecosystem moves in one direction or another. The biota acid tolerance classification (batc) system described herein provides a clear distinction between the taxonomic groups identified in these subcategories and can be used to evaluate the impact of acid deposition on different trophic levels of biological communities.

Physical control of Eurasian watermilfoil in an oligotrophic lake

The introduction of Eurasian watermilfoil (Myriophyllum spicatum) into oligotrophic waters of high water clarity in temperate zones of North America has produced growth in excess of 6 m depth and yearly biomass approaching 1000 g m−2 dry weight. From its initial observation in Lake George, New York, USA in 1985, by 1993 milfoil had spread to 106 discrete locations within the lake. A 7-year study of one site having no management showed milfoil to grow expansively, suppressing native plant species from 20 in 1987 to 6 in 1993 with the average number of species m−2 quadrat declining from 5.5 in 1987 to less than 2 in 1993. Management of milfoil by means of hand harvesting, suction harvesting and benthic barrier has reduced the number of unmanaged sites from 106 in 1993 to 11. One year post-treatment at sites utilizing suction harvesting, showed a greater number of native species at all sites than pretreatment with a substantial reduction in milfoil biomass. At sites where benthic barrier was removed 1–2 years after installation, milfoil had recolonized 44% of grid squares within 30 days. Ninety days after barrier removal 74% of grid squares contained milfoil and one year later 71% of the grids supported milfoil. During the first year following mat removal, the average number of species m−2 peaked at 4.7 and stabilized at 4.5 during the second year. Hand harvesting by SCUBA in areas of limited milfoil growth (new sites of infestation and sites of former treatment) was found to reduce the number of milfoil plants present in subsequent years. Hand harvesting did not eliminate milfoil at any of the sites and regrowth/colonization necessitated reharvesting every 3 or more years. Results of evaluations of physical plant management techniques indicate that (1) an integrated program utilizing different techniques based on plant density reduced the growth of milfoil and (2) long term commitment to aquatic plant management is necessary since none of the techniques employed singly were found to eliminate milfoil.

Use of Geographic Information Systems to monitor and predict non-native aquatic plant dispersal through north-eastern North America

North America has a growing problem with invasive aquatic plants. At every level of the aquatic food web, long-standing checks and balances have become dramatically eroded by the introduction of non-native species. The northeastern United States contains thousands of diverse freshwater habitats, highly heterogeneous in geology and locale, where nuisance aquatic plant growth results in decreased lake water quality, interference with recreational access, degraded flood control structures, and impacts to their aesthetic quality. Early infestation and spread of exotic species is often poorly documented at local and state levels. Consequently, successful management of these species depends on continuous monitoring and definitive identification by both public officials and waterside homeowners. With new mapping capabilities employing software such as Geographic Information Systems (GIS) coupled with the growing computerization of taxonomic records and online availability of regional herbarium records, we have been able to illustrate the␣temporal and geographic spread of these species, thus enabling aquatic ecologists and managers to make predictions of future infestations. In this paper we evaluate these techniques focusing on three of the most pervasive of exotic aquatic plant species in New York State: Myriophyllum spicatum, Trapa natans and Potamogeton crispus.

Brooktrout Lake case study: biotic recovery from acid deposition 20 years after the 1990 Clean Air Act Amendments.

The Adirondack Mountain region is an extensive geographic area (26,305 km(2)) in upstate New York where acid deposition has negatively affected water resources for decades and caused the extirpation of local fish populations. The water quality decline and loss of an established brook trout (Salvelinus fontinalis [Mitchill]) population in Brooktrout Lake were reconstructed from historical information dating back to the late 1880s. Water quality and biotic recovery were documented in Brooktrout Lake in response to reductions of S deposition during the 1980s, 1990s, and 2000s and provided a unique scientific opportunity to re-introduce fish in 2005 and examine their critical role in the recovery of food webs affected by acid deposition. Using C and N isotope analysis of fish collagen and state hatchery feed as well as Bayesian assignment tests of microsatellite genotypes, we document in situ brook trout reproduction, which is the initial phase in the restoration of a preacidification food web structure in Brooktrout Lake. Combined with sulfur dioxide emissions reductions promulgated by the 1990 Clean Air Act Amendments, our results suggest that other acid-affected Adirondack waters could benefit from careful fish re-introduction protocols to initiate the ecosystem reconstruction of important components of food web dimensionality and functionality.

The effect of ozone onLegionella pneumophila and other bacterial populations in cooling towers

Ozone was found to reduce the numbers of bacteria detectable by plate counts and the numbers of presumptiveLegionella pneumophila (DFA-reactive cells), including those that were INT positive, in test cooling towers. The numbers of DFA-reactiveL. pneumophila eventually reached those of the makeup water (Troy, NY, city water). Microbial slime on the interior tower surfaces andPseudomonas populations in the tower waters were also reduced. Water chemistry parameters measured showed no tendency toward a condition that would cause accelerated deterioration of tower material.

Road salt application differentially threatens water resources in Lake George, New York

Abstract Road salt (NaCl) application around Lake George, New York, resulted in nearly tripling in-lake salt concentration between 1980 and 2009. Salt concentrations measured in 8 streams between 2007 and 2009 ranging in development from pristine to moderate resulted in 4 significantly different groups based on chloride concentrations. Chloride concentrations were significantly correlated to the amount of roadway surface within each sub-watershed, with chloride concentrations in the most impacted stream approaching 200 mg/L. In the more impacted streams, chloride concentrations were significantly and inversely correlated to discharge rate. The high road density around the more developed south end accounted for ∼30% of the estimated road salt application, which created a chloride gradient within the lake that decreased as water flowed north to the single outlet. The continual and disproportionate input of road salt near the southern end of the lake strengthened the gradient over time to create 4 significantly different regions within the lake. While the consistent lake-wide increase seems to be open-ended, a steady-state salt concentration within the lake may occur in the near future. Based on change of lake chloride mass and export from the lake (2007–2009), an average lake-wide steady-state chloride concentration of ∼17 mg/L is expected, with some variation anticipated due to interannual variation in precipitation and the salt gradient within the lake.

Augmentation of a Long-term Monitoring Program for Lake George, NY by Citizen Volunteers

ABSTRACT Drinking water standards and recreational demands on lakes and ponded waters place a high priority on the management of water quality. As stakeholders, volunteer citizen monitors can provide considerable assistance to state agencies and research organizations charged with monitoring freshwater resources by accumulating valuable data for water quality evaluation and lake assessment. The Lay Monitoring Program on Lake George (NY) was initiated in 1980 concomitant with the establishment of a long-term chemical monitoring program. By 2002, 23 years of Secchi transparency and surface temperature data had been collected. Results have revealed potential relationships between variations in Secchi transparency and trophic indicators (chlorophyll a and total phosphorus) and have assisted in evaluating the potential influences of both increased recreational use and precipitation regime. Lay monitor participation provides a valuable and cost effective enhancement for ongoing lake chemical and biotic effect studies. The integration of lay monitor Secchi data improves the breadth and consistency of long-term datasets, thereby increasing the program effectiveness in detecting incremental changes in water quality.