Brown Tide Assessment Project in NJ Coastal Waters: A comparison of three bloom years (2000-2002) with two non-bloom years (2003-04): Research Project Summary
Date
2006-08
Date Removed
Journal Title
Journal ISSN
Volume Title
Publisher
Trenton, N.J. : New Jersey Department of Environmental Protection, Division of Science, Research and Technology
Abstract
Brown tides are caused by the rapid population growth (“bloom”) of a minute alga, Aureococcus anophagefferens. To
determine whether these blooms are a threat to coastal waters in New Jersey, the Division of Science Research and
Technology implemented the Brown Tide Assessment Project from 2000-2004. The primary objectives of this study are
to (1) characterize the spatial and temporal occurrence of brown tides in Barnegat Bay-Little Egg Harbor, (2) identify
those environmental factors that may promote the development and maintenance of brown tides, and (3) analyze the
risk of brown tides to submerged aquatic vegetation communities. Category 2 (> 35,000 cells ml-1) and Category 3 (>
200,000 cells ml-1) A. anophagefferens blooms occurred throughout the study area in 2000-2002 (mean abundances
exceeded 190,000 cells ml-1), while none of the monthly means in 2003/04 were classified as a Category 2 or 3 bloom.
Category 3 blooms generally occurred during months with mean water temperatures above 14 C, and a minimum
temperature above 13.5 C; and with mean salinity between 26 and 31 ppt, and a minimum salinity of at least 17 ppt.
However, these environmental conditions do not always result in the occurrence of a Category 3 bloom. Concentrations
of total nitrogen, dissolved organic nitrogen, and nitrite + nitrate were higher during the bloom year of 2002 compared to
the non-bloom years of 2003/04. In contrast, ammonia showed lower concentrations during 2002. Category 3 brown
tides did not occur in any month where the Toms River flow exceeded 200 ft3 sec-1. A Cartographic and Regression Tree
Analysis identified ammonia and dissolved organic nitrogen concentrations, and the Toms River flow, as factors that
distinguished Category 1 (< 35,000 cells ml-1) and Category 3 A. anophagefferens blooms. However, it appears that the
observed differences in nitrogen species concentrations may be a result of A. anophagefferens blooms impacting
nutrient cycles, rather than nutrient levels initiating the brown tides. Analysis of the risk of brown tides to submerged
aquatic vegetation habitat indicated that 50% of the mapped habitat in Barnegat Bay-Little Egg Harbor is potentially at
risk of negative impacts. Graphic displays of the spatial patterns of A. anophagefferens abundance and selected
environmental factors can be viewed at: http://crssa.rutgers.edu/projects/btide/index.html.
Description
Keywords
New Jersey, Brown tide - New Jersey