Mercury in Fish and Wildlife
Mercury is a naturally occurring toxic metal that has become an important environmental and human health concern. Mercury rapidly increases in concentration as is moves up the food chain and can concentrate to high levels in large predatory fish in certain environmental conditions (such as acidic lakes). The Division of Fish, Wildlife and Marine Resources is concerned about the impact of mercury on fish and wildlife and human consumers. While the Department of Health is responsible for protecting human health, and setting fish and wildlife consumption advisories, the Division monitors and studies mercury in the environment.
The Division began monitoring mercury concentrations in fish in the late 1960s and conducted a comprehensive Statewide Toxic Substances Monitoring Program from 1976 until 1993. More recently, the monitoring of fish for mercury occurs primarily for research purposes or is related to specific projects. Continued monitoring is necessary to document changes over time and to evaluate the many lakes and ponds that have never been tested. Also, recent research has expanded to include monitoring of mercury in terrestrial animals, including birds, mammals, and invertebrates. This research is important for identifying areas where mercury deposition and accumulation is high and documenting potential impacts to wildlife populations. Over the last several years, a number of reports and publications on mercury in fish and wildlife in New York have been produced.
Strategic monitoring of mercury in New York State fish
The prevalence of high mercury levels in fish is an important environmental and human health concern. Previous monitoring of fish mercury concentrations in New York identified the Catskill and Adirondack Parks as the principal problem areas in the state. However, fish from only about 4% of New York's 4,000 lakes, ponds, and reservoirs had been analyzed so substantial monitoring gaps remained. Atmospheric deposition is now recognized as the primary source of mercury to most of the state, and recent legislation has led to national and regional decreases in mercury emissions.
In 2003 the NYSDEC began a four-year project to strategically monitor selected fish from lakes, ponds and reservoirs across New York State. This project was supported in large part by funding from the New York State Energy Research and Development Authority (NYSERDA). Fish species targeted were those previously found to accumulate high concentrations of mercury, and included walleye, largemouth bass, smallmouth bass and yellow perch. An objective of the study was to gather new data from waters that had not been surveyed previously. Other objectives included the testing of a model to predict mercury levels in fish based on lake characteristics and water chemistry, and evaluation of changes in mercury in a group of lakes where older data were available. Data gathered by the project were provided to the New York State Department of Health to evaluate the need for fish consumption advisories. Water chemistry data collected during the project were used to evaluate relationships with fish mercury concentrations.
The data showed that fish from most Adirondack and Catskill Forest Preserve lakes have higher mercury concentrations than fish from other regions of the state. A number of environmental and biological variables were shown to be related to mercury levels in fish and simple models were developed and refined to predict mercury concentrations in the four target species. Data from 12 Adirondack lakes were used to evaluate mercury trends in fish over time, and indicated an average decline of 16% in yellow perch mercury concentration over the past 15 years. Data collected for the project were used by the New York State Department of Health to issue new fish consumption advisories on numerous lakes, including region-wide advice for the Adirondack and Catskill Parks.
Read the full report (pdf 2.0 MB)
Trends in mercury concentrations in New York State fish
Abstract
Atmospheric emissions of mercury in the US are being reduced, mercury is being removed from many consumer items, and there is a need to better understand changes in mercury concentrations in fish over time. There is hope that mercury concentrations in fish will decline, and the number of fish consumption advisories due to mercury will decrease. We compared mercury concentrations in yellow perch from a group of Adirondack lakes with data collected 12-17 years earlier and found variable responses among lakes. We observed an average decline of 14% in yellow perch mercury concentrations over the past 15 years. This publication was derived from the "Strategic Monitoring of Mercury in New York State Fish" report.
Citation: Simonin, H. A., J. J. Loukmas, L. C. Skinner, K. M. Roy, and E. A. Paul. 2009. Trends in Mercury Concentrations in New York State Fish. Bull. Environ. Cont. Toxicol. 83:214-218.
Lake variability - key factors controlling mercury concentrations in New York State fish
Abstract
A 4-year study surveyed 131 lakes across New York State beginning in 2003 to improve our understanding of mercury and gather information from previously untested waters. Our study focused on largemouth and smallmouth bass, walleye and yellow perch, common piscivorous fish shown to accumulate high mercury concentrations and species important to local fisheries. Fish from Adirondack and Catskill Forest Preserve lakes generally had higher mercury concentrations than those from lakes in other areas of the state. Variability between nearby individual lakes was observed, and could be due to differences in water chemistry, lake productivity or the abundance of wetlands in the watershed. We found the following factors impact mercury bioaccumulation: fish length, lake pH, specific conductivity, chlorophyll-a, mercury concentration in the water, presence of an outlet dam and amount of contiguous wetlands. This publication was derived from the "Strategic Monitoring of Mercury in New York State Fish" report.
Citation: Simonin, H. A., J. J. Loukmas, L. C. Skinner, and K. M. Roy. 2008. Lake variability: key factors controlling mercury concentrations in New York State fish. Environ Poll 154:107-115.
Assessing mercury in the Delaware, Croton, and Upper Hudson watersheds, 2007
(Report BRI 2009-06 submitted to New York State Department of Environmental Conservation by BioDiversity Research Institute, Gorham, ME)
Summary
Mercury contamination in the northeastern U.S. is well-documented and continues to be a public-health issue of concern. Mercury and its potential toxic effects on terrestrial animals such as songbirds, bats, and raptors has received little attention, yet these species are widely distributed across watersheds and may be exposed to potentially high levels of mercury due to their food habits and habitat needs. Some terrestrial songbird species have been shown to exceed aquatic-based songbirds; even some fish-eating bird species have mercury levels that are lower than terrestrial songbird species that regularly prey on spiders. Spiders and other invertebrate top predators may accumulate high levels of mercury and can have a particularly influential impact on biomagnifying mercury in certain food webs. Aside from spiders, birds rely on calcium-rich prey items for egg laying and bone development in chicks. However, in acidic soils, the abundance of many of the calcium-rich prey species decline. This pattern can have important ramifications on the health of songbird populations, particularly on females laying eggs and on the growth of hatchlings.
To better understand these terrestrial mercury pathways, we sampled leaf litter, soil, songbirds, invertebrates, raptors and bats for mercury and analyzed a subset of songbird, soil and leaf litter for calcium. We obtained 151 samples (3 raptors, 67 songbirds, 15 bats, 51 invertebrates, 8 soil and 6 litterfall samples) from five sites (Bog Brook Unique Area, Bashakill Wildlife Management Area, Great Swamp, Devil's Tombstone and Neversink-Frost Valley) within the Lower Hudson River Valley region of New York, which consisted of the Delaware, Upper Hudson (lower portion) and Croton watersheds.
Except for an Eastern Wood Pewee from Great Swamp, species sampled did not reach or exceed current adverse effect levels. However, songbirds sampled within the three watersheds had some of the highest average blood mercury levels in New York State and the nation.
Read the full report (pdf 1.2 MB)
Assessing mercury exposure and spatial patterns in adult and nestling bald eagles in New York State, with an emphasis on the Catskill Region
Summary
We investigated mercury exposure in nestling and adult bald eagles throughout New York State in response to growing concerns about mercury contamination and effects on wildlife in the northeastern US. This study emphasized the Delaware / Catskill region of New York because this area is subject to notably high rates of mercury deposition, and is the focus of other ongoing investigations. We collected breast feathers and/or blood from nestling bald eagles and shed feathers from adults at nest sites and analyzed these tissues for mercury. Sampling in this study represented 53% of all occupied nesting territories and 69% of all territories fledging young statewide in 2006. We assessed statewide geographic patterns of bald eagle mercury concentrations among seven major watersheds and within the Catskill Park. In addition, we compared results found in this study to those reported elsewhere in North America and assessed potential risks. We also compared mercury concentrations in eagle tissues to those found in local fish.
Average mercury concentrations in eagles from the Delaware / Catskill region, and from the Catskill Park in particular, were higher than levels in other regions of the State and were similar to levels in other populations that were considered elevated. Several sites with elevated mercury levels in fish also had high eaglet blood mercury concentrations; however, overall patterns were inconsistent and varied by fish species and study site. Additional sampling is required to further understand the relationship between fish Hg levels and those found in eagles. The results of this study constitute an initial baseline assessment of Hg in New York's bald eagle populations. Expanding on the knowledge gained through this study is critical to understanding the impact of Hg contamination on eagles and other biota in New York. Recommendations for further study are included at the end of the report.
Read the full report (pdf 871 KB)
