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Visualising nutrients and phytoplankton in the Hauraki Gulf Marine Park using GIS

On this page: abstract, table of contents

Report: TR 2013/50

Author: J Zeldis, J Bind, H Roulston, J Sykes, M Walkington (National Institute of Water & Atmospheric Research Ltd)


The primary production of phytoplankton is a cornerstone of the marine ecosystem in the Hauraki Gulf Marine Park. Phytoplankton use nutrients and light to create their organic structures through photosynthesis, thereby fuelling the aquatic food web and sustaining all life from viruses to whales. Ocean surveying by NIWA has revealed how nutrient inputs from up-welling, rivers and local recycling combine with seasonal cycles of temperature, freshwater input and light to control phytoplankton levels.

Chlorophyll-a is the main pigment that marine phytoplankton use for photosynthesis, and dissolved nutrients (nitrate and ammonium, as well as phosphorus) are key nutrients they utilise. The nitrogenous nutrients, in particular, are critical because their abundance typically sets the upper levels of phytoplankton yield that can be achieved in the coastal marine ecosystem, as well as strongly affecting phytoplankton growth rate.

This report presents geographic information system (GIS) layers and associated metadata for chlorophyll-a and inorganic dissolved nitrogen and phosphorus over the spatial extents of NIWA surveys conducted in the Marine Park region.

The GIS layers are provided for those stakeholders in the aquaculture industry and other users who wish to explore the data to get more information about spatial and seasonal variability of productive conditions in the Hauraki Gulf Marine Park.

Visualising nutrients and phytoplankton in the Hauraki Gulf Marine Park using GIS (1mb)

Table of contents

  Executive summary 5
 1 Introduction
1.1 Productivity at the base of the food web, in the Hauraki Gulf Marine Park
1.2 Scope  6
2 Data acquisition and selection 
3 Seasonal patterns  10 
4 Further reading  14 
  Appendix A: GIS layer plots 15 
  Appendix B: GIS metadata 17