Soil/Leaf Litter-Dwelling Invertebrate Communities of Te Paki
Research team: Olivier Ball (NorthTec), Stephen Thorpe (Auckland University), Mike Fitzgerald (Museum of Te Papa), Patrick Whaley (Department of Conservation, Kaitaia), Steve Pohe (NorthTec)
Our investigations into the Mecodema ground beetle described above also allowed us to study some general aspects of soil and leaf litter-dwelling invertebrate communities within the Te Paki Ecological District. The investigations were done through the use of pitfall traps. Clusters of pitfall traps have been placed within various habitats (native forest, shrubland and pine forest plantation) across Te Paki, from Cape Reinga to North Cape. These have been sampled at different times of the year to gain a picture of how communities at each site change with the season. Most of the beetles and spiders caught in the traps over two years have been identified and interesting patterns are emerging. Native forest is by far the most important habitat for species of beetles and spiders that are endemic to the Te Paki region. Many of the beetles, spiders, and weta caught during the study have not been formally described or are entirely new to science. This supports the general claim that Te Paki is a hotspot for endemism in New Zealand. Invertebrate sorting is ongoing and will hopefully generate clearer pictures of seasonal and habitat changes in invertebrate communities.
Littoral Communities of Te Aupouri Dune Lakes
Research team: Mike Winterbourn (University of Canterbury), Olivier Ball (NorthTec), Steve Pohe (NorthTec)
The dune lakes of the Aupouri Peninsula are a distinctive feature of the Far North and are worthy of protection. Many of the lakes are in serious decline due to a variety of human-induced factors. These include surrounding land uses (mainly agriculture and forestry), introduced weeds and introduced pest fish. Little is known about the invertebrate communities of the littoral zone within these lakes. A 
survey of 17 of the larger dune lakes in the region was undertaken in 2008 to describe these littoral communities and to determine whether community patterns were related to certain lake attributes, most notably trophic status. This could help to identify specific taxa of littoral invertebrates that are useful indicators of lake health. In turn, this could lead to improved management of these sensitive 
lakes. Additionally, the study sought to gain a limited understanding of the littoral zone food webs in the various lakes and identify whether new species have been arriving from abroad. The possibility that climate change will enhance the abilities of warm-loving taxa to invade New Zealand makes this aspect particularly worthy of investigation. As it happens, new taxa have been identified (see Tramea sp. study below), but at present, no taxa have been identified as useful bioindicators of lake health, an interesting observation in itself.
Establishment and Feeding Niche of the Tramea sp. dragonfly in New Zealand
Research team: Steve Pohe (NorthTec), Mike Winterbourn (University of Canterbury), Olivier Ball (NorthTec)
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Photo by Stephen Moore |
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Photo by Kevin Matthews |
Casual observations by one of the research team (SP), lead to the discovery of a nymph of the dragonfly genus Tramea in a Far North dune lake. This genus has never been reported as breeding in New Zealand (though a very small number of adults have been seen here over the past few decades). Members of the genus occurring closest to New Zealand are found in Australia and New Caledonia. The large scale survey of the 17 dune lakes described above was used to ascertain whether Tramea sp. dragonfly nymphs were present in other lakes within the region to try to confirm whether the species was truly established in New Zealand. Lake sampling revealed that Tramea nymphs were present in eight out of the 17 lakes surveyed, confirming the presence of a breeding population of this species in New Zealand ranging from northern to southern dune lakes of the Aupouri peninsula. Gut content analyses are being undertaken to examine how the species is fitting into existing food webs. This may provide information on potential significant impacts, if any, of the species on dune lake food webs in general.
Seasonal Habitat-Use Patterns of Black Mudfish in a Northland Swamp
Research team: Olivier Ball (NorthTec), Steve Pohe (NorthTec), Amy MacDonald (Department of Conservation, Whangarei), Fiona Watson (Department of Conservation, Whangarei), Karen Clearwater (Royal Society Fellow)
New Zealand has five species of mudfish (Neochanna spp.), of which two - the Northland mudfish and black mudfish - live in Northland. All mudfish species are listed as threatened to some degree. The black mudfish, the subject of this study, is listed as a species in ‘Gradual Decline’ since much of its former habitat has been removed (to make way for farming), and much of what is left is 
degraded by other factors (e.g. introduced fish, water level management regimes and livestock). Since 2006, a long term trapping study investigating the seasonality and habitat requirements of the black mudfish has been undertaken at one of its Northland strongholds at Hikurangi Swamp near Whangarei. Several habitat types; manuka shaded, open sedgeland, pond and reed bed, have been sampled over time at 
50 sites. Generally, surveys have shown shaded manuka to be the preferred habitat. This was expected as previous studies elsewhere in New Zealand indicated that black mudfish require significant overhead vegetation in order to survive. More surprisingly, large numbers of black mudfish have also been caught in open sedgeland at Hikurangi, showing that this habitat type is also suitable. No mudfish have ever been caught at the small number of pond sites. As well as the number of mudfish caught and their length, surveys have collected other information, most notably the number of mosquito fish (Gambusia affinis) caught in the traps, and the extent of cattle damage in the area. Mosquito fish are known to attack juvenile mudfish and damage to wetland habitats by cattle has the effect of opening up the habitat, likely making it more suitable for mosquito fish. The study aims to unravel these complex interactions over time. Our hope is that this will lead to improved methods for managing what is left of mudfish habitats in Northland and the rest of New Zealand.