Detail view for dataset: Assessment of Historical Phytoplankton Characteristics and Bloom Phenomena in the New York Harbor Estuarine and New York Bight Ecosystems

Region: Western Long Island Sound, Upper East River, Lower East River, Upper North River, Lower North River, Upper Harbor, Upper Jamaica Bay, Lower Jamaica Bay, Lower Bay, Kill Van Kull, Raritan Bay, Sandy Hook Bay, North Jersey Coast, Mid Jersey Coast and South Jersey Coast
Author: Dr. Elizabeth M. Cosper
Sponsor: The Hudson River Foundation
Organization: Coastal & Environmental Studies, Inc.
Last Updated:
Organization: Coastal & Environmental Studies, Inc.

Intro:
Objective: The purpose of this study is to compile existing data sets so as to characterize normal and excessive (blooms) phytoplankton conditions and to determine the location, extent, impacts and factors contributing to the blooms in water bodies of interest to the NY/NJ Harbor Estuary Program.
Abstract: The purpose of this study is to compile existing data sets so as to characterize normal and excessive (blooms) phytoplankton conditions and to determine the location, extent, impacts and factors contributing to the blooms in water bodies of interest to the NY/NJ Harbor Estuary Program. There are four major monitoring programs from which data were obtained: the New York City, Harbor Survey, New York City Department of Environmental Protection (NYCDEP); the Interstate Sanitation Commission (ISSC); the New Jersey Department of Environmental Protection (NJDEP) in conjunction with the US Environmental Protection Agency (USEPA); and the Gateway National Park, National Park Service (NPS). The compiled data addresses the following topics:Chlorophyll a- Index of Phytoplankton Abundance, Phytoplankton Species and Biomass, Bloom Conditions Versus Environmental & Water Quality Variables, Algal Bloom Index: Nature of Bloom Impacts and Historical Analysis of Bloom Impacts.
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Processing method: Chloyophyll a is frequently used as an index of phyto plankton biomass and therefore we calculated the long term chlorophyll means for each site for each month of survey in each of the four prgrams. So as to integrate the data sets, sites from the different programs were combined into regional entities and plotted over two decades from 1975-1995, month by month with the long term means for each area indicated by a solid line. Excessive phytoplankton conditions were defined on three bases, first as values which exceed by two fold the long term mean for an area (Chl>2xMean) and secondly as chlorophyll values, which would tend to color the water, levels greater than 20ug/liter (Chl>20) or thirdly greater than 40ug/liter (Chl>40). These conditions were then termed blooms. Phytoplankton enumeration was available for 1991, 1992 and 1993 from the Harbor Survey and 1991 and 1992 from the NJDEP. One of the biggest problems in phytoplankton ecology is how to convert numbers (cells/ml) to biomass since many of a small species are not necessarily equivalent to numbers of a large species. An accepted practice that has been utilized since Strathmann (1967) is to convert to cellular carbon from the average volume using an equation developed from culture ralationships between cell volume and carbon content. We converted all the phtyoplankton cell counts to phytoplankton carbon similarly for the Harbor survey data. Since we have both phytoplankton species enumeration and chlorophyll a measurements for 1991, 1992 and 1993 surveys, correlations between biomass estmates both as phytoplankton carbon using the above method with the chlorophyll measurements as an index of biomass were conducted. If a good correlation could be established, then phytoplankton species counts could be converted into chlorophyll estimates to compare in a historical context to the long term chlorophyll data sets. We correlated water quality and environmental variables with bloom conditions as indicated by chlorophyll levels. Multiple correlation analyses for chlorophyll a (CHL A, ug/l), salinity (SAL, ppt), Temperature (TEMP, C) (top & bottom), dissolved oxygen (DO, mg/l) (top & bottom), biological oxygen demand (BOD, mg/l) (top & bottom), turbidity (TURB, Jackson Trubidity Units & FHU), ammonia (NH3, mg/l), nitrate (NO3, mg/l), total phosphorus (PHOS, mg/l), dissolved phosphorus (ORTHO, mg/l) and total organic carbon (ORG-C, mg/l) were performed for all regional sites and for each region separately. We have developed an "Algal Bloom Index" which quantifies the severity and extent of a bloom so as to characterize the nature of the impact. There are five levels of severity: 1. the water is discolored and clarity is reduced, 2. oxygen is reduced to hypoxic levels, <5ppm but <3ppm, 3. toxicity to fauna occurs and/or dissolved oxygen is reduced <3ppm, 4. mild toxicity to humans occurs and 5. severe toxicity to humans. The extent of the bloom is coded as low (less than a week in a small restricted area), medium (over several weeks in several areas) and high (over several months in extensive areas). Combining severity level with extent can generate an "Algal Bloom Index" (ABI) from 1 to a maximum of 15. The characterization of the bloom impacts were gleaned from annual reports and published literature as much as possible so as to evaluate both the historical trends as well as area the most severely impacted environmentally. Blooms were evaluated from 1957 to 1995; pre-1957 blooms are largely undocumented.
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