Firth of Thames Ramsar Site
Benthic fauna of the intertidal mudflats
DRP students in 2001 and 2002 worked on the development of effective methodologies for the sampling of benthic fauna of the intertidal mudflats along the Miranda-Kaiaua Coast. Benthic fauna monitoring was subsequently carried out during several semesters by way of field exercises. The data collected contributes to the much-needed information on the food availability for migratory waders that use the area. Benthic fauna of the mangrove (Avicennia marina) areas was also investigated. Other projects in the mangals at Miranda documented biota that lives on the trees.
Fishes of the Miranda Stream
The lower reaches of Miranda stream form part of an estuarine habitat that supports a diverse fish fauna. EcoQuest students sampled the stream over several semesters. Using traps and nets, and a catch and return practice, samples were taken along transects spanning estuarine to freshwater conditions. Thirteen species of fish were recorded. Both freshwater and marine species were found. Several are migratory and present in these lower stream estuaries during only part of their life cycle. Differences in size class, abundance and diversity of fish species were found between spring and autumn sampling and between sites. Life stages and lifecycles of the species were documented.
The latest contribution to the fish projects has been a comparative survey in the Waihihi stream 12 km north of Miranda. This stream runs through forest and farmland and enters the coast on a pebble beach where there are no mangroves.
To contribute to the understanding of the dynamics of the intricate food web of species (through tidal, diurnal and seasonal changes) in the Miranda environment, we plan to replicate these fish studies. Surveys of the invertebrate fauna of the stream and estuary were carried out. Students also investigated the vegetation and invertebrates of the salt marsh and pastureland adjacent to the shell-banks of the Miranda Chenier Plain. The focus was on community composition, and comparisons between habitats of the proportion of native and exotic species.
Feeding ecology of waders
In 2005, students reviewed the feeding ecology of waders of the Firth of Thames, and the potential effects of sediment on benthic fauna. Outcomes of these studies may lead to large scale sampling to assess diversity of benthic fauna, and/or long-term monitoring of known food sources of waders of the Firth of Thames.
Activity of mammalian predators at the Miranda Wildlife Refuge
During the Spring semester of 2003, a study was initiated investigating the presence of introduced mammalian predators in the roosting habitat for waders. This study was repeated in Fall 2003, and extended in 2004.
In order to detect and document presence of mammalian predators not easily observed in the field, students used tubular tracking tunnels to record animal footprints. Tracking tunnels are commonly used as a tool to target and monitor pest control and ecological restoration programmes in New Zealand. A piece of bait is placed inside, at the centre of the tracking tunnel. In order to reach the bait the animal must walk over an inkpad. As the predator leaves the tunnel it leaves its footprints on a tracking card. By examining the footprints on the card, students identify the species of animals present and the number of cards with prints provides an index of activity. Data from the preliminary study in April / May 2003 suggested that the presence of cats at Miranda may limit the presence of stoats (Mustela erminea). The tracking tunnel study was extended in Nov-Dec of 2003. Additional tunnels were used, and students contributed to a trapping programme (initiated by DoC, and run with the help of the Miranda Shorebird Centre and EcoQuest).
Snails
Some of the issues related to the use of tracking tunnels include the problems encountered when brown garden snails (Cantareus asperses) enter the tunnels: they leave trails, obliterate trails and consume the cards, resulting in less reliable interpretation of data. The idea that reduction of the amount of cover and increasing distance between tunnels, might lessen the visitation rates by snails, sparked a study into the desiccation rates of snails in 2004.
Invertebrate footprints - key to identification?
The use of tracking tunnels for small mammals often yields prints of invertebrates as well. A pilot study, to investigate whether insects can be identified from their footprints, was conducted in November 2003. A second team of students continued to explore the application of this idea. This study was conducted in close collaboration with Connovation® Ltd (Conservation by Innovation), which is investigating identification of insect footprints as a tool for detection of alien organisms in overseas cargo. Initial results suggested that the method has limited potential for biosecurity monitoring, but does have potential for applications in conservation monitoring, especially for large invertebrates such as weta (Deinacrida spp.; Hemideina spp.)
