Vol.10 No.4 - December 2002

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Mark Gall
A new instrument is contributing to a greater understanding of the dynamics of the ocean, especially in the coastal zone.
Diagram of the BIOFISH, showing the main components. The wings and towing bridle can be adjusted to alter the flight characteristics.
Physical processes create the conditions for many biological processes in both open oceanic and coastal waters (see “The coastal ocean of New Zealand” below). This biophysical coupling and the dynamics of the marine ecosystem determine the variability we observe.

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Kit Rutherford
A new catchment model is being designed for use by non-specialists.
It is widely accepted that agriculture is not good for streams.

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Janet Bradford-Grieve
Stuart Hanchet
By increasing our knowledge of food webs we are learning more about the resilience of marine and freshwater ecosystems and the effects of fishing on the relationships between species.
Ocean colour from the satellite-borne SeaWiFS sensor can be used to estimate the biomass of phytoplankton near the sea surface.
Anyone involved in fisheries is required by the 1996 Fisheries Act to maintain the number of associated or dependent species above a level that ensures their long-term viability, and to maintain the biodiversity of the

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Pip Nicholls
Help is available to assess the threat posed by sediment inputs to estuaries.
Some key dump signs: Brown clay covering coarse sand and shell.
Some key dump signs: Abrupt changes from sand to mud.
Threat indicators: Removal of vast areas of vegetation.
Threat indicators: The mud crab Helice crassa is an excellent bioturbator.
Managing soil erosion: A sediment screen around a culvert adjacent to road works.
Estuaries are important sites for many biological and physical processes, yet they are often taken for granted.

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Pip Nicholls
Joanne Ellis
Investigations into changes in salt marsh and mangrove communities are confirming the important role of increasing sedimentation.
Saltmarsh in Mangemangeroa Estuary, Auckland.
Extensive root and pneumatophore system of a mangrove tree, Waikopua Creek.
Map of the Whitford Embayment
Sediment core from Waikopua Creek showing depth profile.
Fringing plant communities, such as salt marshes and mangroves, play an important role in our estuaries and coastal ecosystems.

Bob McDowell takes a new look at the reasons for the decline of the freshwater mussel – kakahi – challenges one of the presumed causes of the decline.

On this page
NIWA’s southernmost technician and the 2002 ozone hole
NIWA’s Tide Forecaster
GIS mapping: showing great potential!
Murky waters: Remote sensing of New Zealand’s coasts and lakes
Air pollution and health
NIWA scientists help phytoplankton to bloom in Gulf of Alaska
NIWA’s southernmost technician and the 2002 ozone hole
The interior of the Arrival Heights laboratory.
Total ozone levels measured using the Dobson spectrophotometer at Arrival Heights, Antarctica.
NIWA’s 2002–03 field programme of atmospheric measurements in the Antarctic

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Niall Broekhuizen
John Oldman
Individual cells can differ from each other. This could be important in attempts to predict how populations of phytoplankton might respond to changes in the ocean.
Image 1 Results from the Lagrangian model run in an area of north-east New Zealand.
Image 2 Location map for the study area.
Image 3 Variability and relative differences in predictions made by the two types of model
We all recognise that no two people – except, perhaps, identical twins – are exactly the same.

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Roy Walters
A new, widely applicable computer model may improve our understanding of sediment accumulation in estuaries.
Layers of flow over a rough river bed.
Comparison between model data and experimental results for rough-bed flow.
Did you ever ask yourself why rivers sometimes look dirty, and where all the mud in an estuary comes from?
Sediment is picked up by a river all along its course, from the river bed and banks, and from land around the river when it is in flood.

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Judi Hewitt
Research is underway to pin down the effects of increasing sediment inputs to coastal waters on some of New Zealand’s important shellfish species.
Cockles
Pipi
Horse mussels
In New Zealand, changes in land use (such as deforestation and urbanisation), and modification of coastlines have increased sediment build-up in coastal environments. Suspended sediment concentrations in estuaries and along the coasts can increase by orders of magnitude for hours to several days following erosion during storms.