Vol.13 No.3 - September 2005

Forests of kelps fringe rocky shores and reefs around New Zealand. Kelps, such as these Lessonia growing in the Chatham Islands, form canopies that provide shelter, food, and habitat for many other species. Read how scientists at NIWA are learning lessons from Cook Strait Lessonia.

In this issue

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    More than just a crab hole

    PDF of this article (310 KB)
    Helice crassa, the tunnelling mud crab. (Photo: K. Vopel)
    Measuring dissolved oxygen, hydrogen sulphide, and pH using electrochemical microsensors. (Photo: K. Vopel)
    The fragile microelectrodes are inserted into the mud in 0.1 mm increments. (Photo: K. Vopel)
    (Photo: K. Vopel)
    Kay Vopel and Nicole Hancock explore the labyrinth of burrows beneath mangrove mud and describe the vital chemistry within.
    Mangrove trees trap fine sediment brought in by rivers and the tide.
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    Horrible hornwort threatens South Island lakes

    PDF of this article (271 KB)
    Hornwort. (Photo: R. Wells)
    Current distribution of hornwort in New Zealand waterways. (Map: FBIS)
    Lake weed caught on a boat trailer. This is a typical way for weeds like hornwort to spread to new sites. (Photo: J. Clayton)
    Capable of growing taller than a three-storey building, hornwort is the latest aquatic weed to invade our waterways and lakes. Fleur Matheson, Rohan Wells, and Kay Vopel map its spread through New Zealand.
    Hornwort is currently considered New Zealand’s worst submerged weed.
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    Life beneath the ice

    PDF of this article (731 KB)
    Tabular iceberg in the Ross Sea. (Photo: R. Budd)
    Sampling sites along the Victoria Land coast. (Map: B. Wood and E. Mackay)
    Still from the video shows the macroalga Iridaea cordata attached to rocks. (Video: G. Funnell)
    Multibeam imagery shows iceberg scour on the seafloor. (Images: R. Kvitek, Seafloor Mapping Lab, Monterey Bay, California)
    Opening the dredge haul and sorting the contents. (Photos: R. Budd)
    Preparing to unload the grab sampler. (Photo: R. Budd)
    RV Italica moored at the edge of pack ice. (Photo: G.
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    Where do those BIG fish come from?

    PDF of this article (194 KB)
    Inanga. (Photo: S. Moore)
    Inanga lay their eggs above normal river levels within vegetation that is flooded by spring tides. Heavy grazing on the lower reaches of the Waikawau limits the amount of spawning habitat. (Photo: J. Richardson)
    Length frequency graphs for inanga captured in the Waikawau and Nukuhou rivers in December 2004 and March 2005.
    Restoration of inanga populations to enhance whitebait fisheries depends on improving both spawning and rearing habitat. But which is most important?
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    Living in the ocean waves: kelp life histories

    PDF of this article (293 KB)
    A Cook Strait kelp forest with Lessonia variegata and Ecklonia radiata. (Photo: S. Shiaparelli. University of Genova)
    Heteromorphic life cycle of true kelps. (Graphic: Erika Mackay)
    Close up of Lessonia shows the chocolate-brown sorus (arrow) on the surface of the blade. (Photo: S. Shiaparelli. University of Genova)
    Wendy Nelson and Anne-Maree Schwarz report on the sex lives of large brown algae.
    Around the coasts of New Zealand, forests of brown seaweeds fringe the rocky shores and reefs.
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    Banded Kokopu: sniffing out a good home

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    Juvenile banded kokopu. By this age the fish will have found their way to their preferred habitat. (Photo: S. Moore)
    Cindy Baker, Guy Carton, Jared Fine, and Peter Sorensen are investigating whether bile acids serve as chemical cues for whitebait looking for suitable habitat.
    The banded kokopu (Galaxias fasciatus) is one of the five species supporting New Zealand’s nationwide whitebait fishery. Like inanga, the banded kokopu is diadromous, migrating between fresh and salt water during its life cycle.
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    Mud, glorious mud

    PDF of this article (282 KB)
    A mussel farm in the Firth of Thames in New Zealand's North Island. (Photo: H. Giles)
    Sediment clay distribution in the Firth of Thames. (Click for detail.)
    Peter Gerring wrangles the multi-corer onboard RV Kaharoa. (Photo: J. Zeldis)
    Kim Currie sets up sediment incubation experiments for measuring nutrient fluxes and denitrification rates. (Photo: J.
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    Award-winning kina research - Wetland construction at Lake Okaro - Ecological engineers - French Polynesia at Bream Bay

    Award-winning kina research.
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    Coralline algae guide - Bird's-eye view of estuaries - Training at NIWA - New at Kelly Tarlton's - Project Q - Enquiring minds want to know

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    Classifying caddis - Ancient glass sponges

    PDF of this article (153 KB)
    Classifying caddis
    Zelandoptila moselyi larva and adults (male and female). (Photos: B. Smith)
    Commonly known as a caddisfly, Zelandoptila moselyi is a small insect belonging to the aquatic order Trichoptera. The larva (or juvenile) is thought to live on submerged wood in streams; the adults are dull, moth-like insects that fly at night.
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    Sampling the depths

    PDF of this article (232 KB)
    Sampling the depths: seamount life over 2 km down
    A new species of galatheid shrimp, showing the heavy body and strong spines to deter predators. (Photo: M. Clark)
    Swath map of Young Nicks Seamount.
    The seafloor at 2600 m depth on Gisborne Knolls.
    In November last year, scientists on RV Tangaroa deployed sampling and photographic equipment on two seamounts off Hawke Bay at depths up to 2950 m.
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    Tracy Farr talks corallines and cookery

    PDF of this article (208 KB)
    Tracy examines coralline algae growing on kelp in the Chatham Islands. (Photo: K. Neill)
    Algal researcher Tracy Farr has been known to take her work home – and into the kitchen – applying her culinary expertise to laboratory leftovers. She’s well known at NIWA’s Greta Point, Wellington, site for her work with coralline algae and other seaweed. Last January she received wider exposure when National Radio took her to the beach to discuss her seaweed recipes on Summer Report.
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    Meet the Q team

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    Barnaby, Chelsie, Tess & Paora are coming soon to TV One.
    QTV is on the way. This dynamic new multimedia series explores real-world science issues – presented for kids by kids. QTV takes science out of the classroom and goes wherever real scientists are working, whether it’s underwater with spider crabs, on the edge of a volcano, or brewing bugs in the lab.
    NIWA is proud to be a sponsor of this 13-part television series.
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    Curriculum connections: using this magazine as a classroom resource

    PDF of this article (59 KB)
    One of NIWA’s aims with this magazine is to contribute to science education in New Zealand. To this end we distribute Water & Atmosphere without charge to New Zealand high schools. Most of the magazine’s articles are assigned ‘Curriculum Connections’ to indicate which of the NZ NCEA Achievement Standards they can complement as a classroom resource.