Freshwater invertebrates of Campbell Island revealed

In this guest post aquatic scientist Shelley McMurtrie writes about the results of an expedition to a subantarctic island.

It’s a proud day when a scientist has a discovery named after her (thanks Adrian Pinder!) In the field of invertebrates the chance of finding a new species is certainly greater than, say, working in the field of mammals, but even so, it is a rare privilege and one thing on my bucket list that I didn’t think I would ever tick off.

In my case, my surname (McMurtrie) is being shared with a tiny worm (Macquaridrilus mcmurtrieae) that lives only in the streams and tarns of the remote subantarctic island known as Campbell Island/Motu Ihupuku.

You can meet my namesake – and 35 other individuals – in the first interactive key (and associated information sheets) to the freshwater invertebrates of Campbell Island to ever be published.

Campbell Island is well known for its beautiful display of colourful megaherbs but it is also home to a vast freshwater network that has been poorly studied in the past. Photo © Shelley McMurtrie

Campbell Island is well known for its beautiful display of colourful megaherbs but it is also home to a vast freshwater network that has been poorly studied in the past. Photo © Shelley McMurtrie

Campbell Island/Motu Ihupuku is a special place, with lots of plants and animals unique to the island. It lies 700 kilometres south of New Zealand’s mainland, the most southerly of the five New Zealand subantarctic groups. It was once farmed, but it has been free of introduced animals (such as sheep and rats) since 2001 and has UNESCO World Heritage status for its outstanding natural values. Campbell Island is world famous for its unique and colourful megaherbs, one of the largest colonies of royal albatross, and because it was the focus of the world’s largest (and successful) island rat eradication programme.

I was privileged to visit in 2010, as part of the Campbell Island Bicentennial Expedition – a multi-disciplinary research expedition marking 200 years since the island’s discovery by Europeans. I led a small team of freshwater ecologists whose mission was to unravel the mysteries of the freshwater environs, nutrient subsides (finding out how much the marine environment subsidises the food web of land-based habitats such as streams), and past climatic and environmental changes.

The streams on the island were very different from each other and even varied along their length. In its headwaters Camp Stream is almost an underground stream, carved deep into the peat layers and covered over with vegetation. Photo © Shelley McMurtrie

The streams on the island were very different from each other and even varied along their length. In its headwaters Camp Stream is almost an underground stream, carved deep into the peat layers and covered over with vegetation. Photo © Shelley McMurtrie

It was the most comprehensive aquatic sampling programme to ever take place on the island. We collected aquatic invertebrates, periphyton (algae), microbes (single-cell organisms), samples to test water and sediment quality, and samples to test for stable isotopes (carbon and nitrogen signatures that tell us whether the energy flow in food webs is sourced from marine or terrestrial sources) from 25 streams and 9 tarns. We also sampled 34 tarns for water and sediment quality. The 235 invertebrate samples collected as part of this research programme were used to develop the invertebrate keys.

We discovered that Campbell Island’s streams and tarns are home to a moderately diverse range of freshwater invertebrate species, with the 36 taxa being a big increase from the 16 taxa previously documented from streams on the island. Many of these are  are unique to the island, which is not surprising, considering its isolation and the harsh environment. But what is equally interesting is that the island also plays host to some of the same species that are found on mainland New Zealand – such as the common caddis fly, Oxyethira albiceps.

In its mid to lower reaches Camp Stream is wide and cobble-lined, and runs through a Dracophyllyum ‘dwarf forest’. Photo © Shelley McMurtrie

In its mid to lower reaches Camp Stream is wide and cobble-lined, and runs through a Dracophyllyum ‘dwarf forest’. Photo © Shelley McMurtrie

We also discovered there is a very high diversity of aquatic oligochaetes (worms). We have only had 2% of the oligochaetes identified and already there are 17 different taxa, so there is a great potential for more new species or new records for the island. They do not form part of the identification key yet, as we will need more funding to go through the almost 9,000 oligochaetes we found in the samples before we can properly describe them and unravel the mysteries of this little known group on the island.

All new knowledge of our world, even in far-flung places such as the subantarctics, helps build the bigger picture of life on earth. Understanding threatened ecosystems and the species they contain enables better conservation strategies to be implemented. Campbell Island is worthy of the best level of protection we can provide. And not just because my namesake calls it home.

Sampling the many streams of the island was of great interest to the numerous sea lions on the island. Photo © Shelley McMurtrie

Sampling the many streams of the island was of great interest to the numerous sea lions on the island. Photo © Shelley McMurtrie

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 the TFBIS (Terrestrial and Freshwater Biodiversity Information System) Fund.

The key can be accessed at http://ciinvertkey.com/.

Alex James (left) and Shelley McMurtrie (right) of EOS Ecology having lunch tucked in out of the strong winds. Sampling the streams relied on good old-fashioned foot power, and packing in all the sampling gear. Photo © Shelley McMurtrie

Alex James (left) and Shelley McMurtrie (right) of EOS Ecology having lunch tucked in out of the strong winds. Sampling the streams relied on good old-fashioned foot power, and packing in all the sampling gear. Photo © Shelley McMurtrie

Shelley McMurtrie, principal scientist at EOS Ecology, Christchurch, specialises in studying New Zealand’s freshwater systems. She was the coordinator for the Campbell Island Bicentennial Expedition and leader of the freshwater research team, which was supported by the 50º South Trust.

The key was published online by EOS Ecology thanks to funding from TFBIS and EOS Ecology.

Leave a comment

By posting comments you signify that agree to and accept the Terms and Conditions of this Blog.

Please enter current year *