Principal Investigator: Ann Bucklin (Director of Marine Sciences, University of Connecticut)
From April 2002 through June 2004, the Regional Ecology and Coastal Hydrography (REACH) project conducted monthly field sampling in the western Gulf of Maine. REACH is one of five seed projects associated with the UNH center of excellence for Coastal Ocean Observing and Analysis (COOA). COOA is developing and implementing new methodologies and approaches for coastal ocean observing across the spectrum from data acquisition, analysis, integration and synthesis.
The objective of REACH is to document and understand the functional inter-relationships among the major elements of the planktonic assemblage in the waters of western Gulf of Maine. The field program characterized the physical dynamics, nutrient availability, and phytoplankton and zooplankton assemblages. A long-term goal of this effort is to work toward a predictive index of harmful algal bloom (HAB) occurrences in near-shore waters of the western Gulf of Maine based on an integrated assessment of the planktonic community. The comprehensive nature of the study also enables this work to serve as a baseline for the western Gulf of Maine, against which future studies can be compared.
An innovative aspect of this project is the integrated analysis of the entire planktonic assemblage at the species level - including both phytoplankton and zooplankton species abundances in the same samples that are used to determine toxic dinoflagellate counts. In addition, we will ensure detailed examination and characterization of the physical oceanographic and meteorological setting from real-time data derived from satellites, remote sensors on buoys, and commercial fishing boats.
The Gulf of Maine and Georges Bank contain over 25 species of pelagic copepods. The high species diversity is particularly noteworthy given the low diversity of their habitat, planktonic lifestyle, and generalist foraging strategies. Copepods are the most abundant animals in the Gulf of Maine and they occupy a pivotal niche in the planktonic food web: they are important consumers of phytoplankton and are in turn consumed by the larvae of many commercially important fish. While the zooplankton assemblage has been intensively studied in the Gulf of Maine and Georges Bank, we believe this is the first multi-year study to examine vertical as well as year-round patterns of abundance in the coastal waters of the Western Gulf of Maine.
The Gulf of Maine is not a homogeneous body of water; the complex bathymetry lend to complicated circulation patterns. The Western Gulf of Maine Coastal Current tends to move water southwest paralleling the coastline, and is composed of nutrient rich waters which support higher concentrations of phytoplankton than the central waters of the Gulf of Maine. This current does not tend to mix with water entrained in and over the deeper portions of the Gulf of Maine, making this region a useful laboratory to understand local, coastal processes occurring in our test bed, semi-enclosed sea.
Our central hypothesis is that abundances and blooms of toxic dinoflagellates are controlled by the planktonic community dynamics. In particular, we hypothesize that a significant factor controlling Alexandrium abundance in the Maine Coastal Current is the competition between the toxic dinoflagellates and planktonic diatoms for nutrients, particularly in coastal regions where salinity ranges are optimal for growth of both. We expect that where diatoms are abundant, they will exhaust the supply of nitrogen, and Alexandrium will not bloom; in contrast, Alexandrium blooms can form where silicate limitation prevents diatom growth.
Data analysis is designed to understand and interpret the planktonic assemblage as a community of interacting and competing species. We are using a powerful software tool developed specifically for multi-species analysis in a realistic environmental context: Plymouth Routines In Multivariate Ecological Research (PRIMER ver. 5, 2001), which includes a range of univariate, graphical, and multivariate routines. Multidimensional scaling (MDS) and principle components analysis (PCA) are used to view overall trends in the community.
In addition to the diverse types of data collected during our research cruises, we will use satellite imagery available through Web-COAST, and real-time physical oceanographic and meteorological data from GoMOOS buoys and commercial fishing vessels participating in the COOA-funded FleetLink project (see http://www.cooa.unh.edu).