Vol.10 No.4 - December 2002

Kim Thomas, NIWA’s southernmost technician, checking the solar tracker for the infrared spectrometer on the roof of the Arrival Heights laboratory, Antarctica, in October 2002. The infrared spectrometer – which measures a range of trace gases – is one of the instruments used in NIWA’s Antarctic atmospheric measurement programme. The programme includes tracking the progress of the ozone hole which forms in spring each year. See “NIWA’s southernmost technician and the 2002 ozone hole” for more details.

In this issue

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    Let's get biophysical! - with BIOFISH

    PDF of this article (1 MB)
    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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    Can we simplify catchment planning?

    PDF of this article (830 KB)
    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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    Understanding ecosystems: a key to managing fisheries?

    PDF of this article (522 KB)
    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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    Sediment dumps in estuaries: filling in the gaps with a risk map

    PDF of this article (797 KB)
    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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    Fringing habitats in estuaries: the sediment-mangrove connection

    PDF of this article (731 KB)
    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.
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    Decline of the kakahi - identifying cause and effect

    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.
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    NIWA news forum

    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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    Between-individual variations modify phytoplankton dynamics

    PDF of this article (923 KB)
    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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    Sediments and models: do they mix?

    PDF of this article (574 KB)
    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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    Effect of increased suspended sediment on suspension-feeding shellfish

    PDF of this article (502 KB)
    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.
    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.