By Shelley McMurtrie
New Zealand’s subantarctic islands are a UNESCO World Heritage site of unparalleled beauty and outstanding natural values. One of these islands—New Zealand’s most southern landmass Campbell Island—is home to several globally rare species including its unique and colourful megaherbs, and one of the largest colonies of royal albatross.
With an ever-increasing need to protect biodiversity values and understand how climate change will affect world ecosystems, the Subantarctic region is assuming increasing significance. However, our knowledge and understanding of the extensive freshwater ecosystems (streams, lakes, and tarns) of these remote islands is limited. Our newly published online identification key to the freshwater invertebrates of Campbell Island goes some way to bridging that information gap.
I was privileged to visit Campbell Island in 2010, as part of the Campbell Island Bicentennial Expedition—a multi-disciplinary research expedition marking 200 years of occupation. I led a small team of freshwater ecologists whose mission was to unravel the mysteries of the freshwater environs, nutrient subsidies, and past climatic and environmental changes.
It was the most comprehensive aquatic sampling programme of the island to date. We collected benthic aquatic invertebrates, periphyton, microbes, water quality, sediment quality, and stable isotope samples from 25 streams and 9 tarns, and sampled 34 tarns for water and sediment quality. The 235 benthic aquatic invertebrate samples collected as part of this research programme were used to develop two online identification keys covering the island’s freshwater invertebrate fauna. Working with Professor Mike Winterbourn of University of Canterbury and taxonomists from around the world, we have been able to describe 36 taxa in the key and associated information sheets.
Overall we found that Campbell Island’s streams and tarns are home to a moderately diverse range of freshwater invertebrate species, and that many of them are unique to the island. This is not surprising, considering its isolation and the harsh environment. But equally interesting was that the island does also plays host to some of the same species that are found on mainland New Zealand—including the hydroptilid caddis fly, Oxyethira albiceps—despite the 700 km of southern oceans between the two islands.
One of the most interesting features has been discovery of not only the abundance of aquatic oligochaetes (worms), belonging to the orders Tubificida and Enchytaeida (Class Clitellata), but also a very diverse one. With almost 9000 individuals, oligochaetes were the third most abundant order in our freshwater samples. We have only begun to fully elucidate this fascinating group and already they are proving to be one of the most diverse. Adrian Pinder of the Department of Parks and Wildlife (Western Australia) was commissioned to assist in the Oligochaeta identifications. To date he has identified seventeen different oligochaete taxa (including several potential new species) and this is only from a fraction (2%) of the total specimens collected. One has been formally described by Adrian Pinder as a new species (Macquaridrilus mcmurtrieae), which I have had the privilege of being named after me, as leader of the freshwater ecology research team that collected the samples. An article outlining the find (Pinder & James, 2014) has been published in NZ Journal of Zoology.
Out of this work we have had new distribution records (including the blastocladial fungus, Coelomycidium sp. infecting the sandfly Austrosimulium campbellense), and other possible new species pending confirmation via DNA work in the flatworm and nemertean groups.
With the exception of M. mcmurtrieae the oligochaete group has not been fully described in the identification key as we first need additional funding to properly identify the remaining oligochaetes, which will greatly benefit the identification and understanding of this widely distributed but lesser known group.
We are grateful for the many people that contributed to making this key come together, including 50º South Trust who made the original expedition possible, and TFBIS (Terrestrial and Freshwater Biodiversity Information System) Fund. We are proud to be able to share this comprehensive resource with you—you can access it at ciinvertkey.com.
Shelley McMurtrie is principal scientist at EOS Ecology.