Freshwater survey at Waituna

Department of Conservation —  04/10/2014

By Emily Funnell, Technical Advisor – Aquatic and Reporting Unit

Earlier this year we carried out a survey in some of the ponds and bog tarns in Southland’s Waituna catchment.

This work was undertaken as part of DOC’s Arawai Kakariki wetland restoration programme in the Awarua-Waituna Wetlands.

Waituna wetlands sign. Photo: itravelNZ | CC BY 2.0.

Waituna Wetlands

We have always known that giant kōkopu, kōura/freshwater crayfish and other species can be found lurking in in the tarns and ponds, but we have never known how extensive their habitat was.

Freshwater crayfish/kōura.

Freshwater crayfish/kōura

In April we had a peek in a number of ponds all around the catchment, many on public conservation land, but also a few on private land.

Surveying for freshwater fish at Munroe Dam.

Surveying in the Munroe Dam

I would like to be able to say that we found these waterways teeming with fish, but unfortunately only a couple of sites fitted this description.

Giant kōkopu. Photo: Andy Hicks.

Giant kōkopu in the Waituna catchment

Giant kōkopu and other freshwater species were largely absent from most of the catchment ponds, except at the Munroe Dam and in the tarns on the southern side of the lagoon. These two sites had more giant kōkopu than we could shake a stick at, and with a good range of sizes.

Giant kōkopu. Photo: Andy Hicks.

Giant kōkopu

Unfortunately, the ponds and tarns around Carran Creek, and those to the west of Waituna Creek, were all devoid of freshwater fish. This indicates that we may have been overestimating the use of these habitats by fish—with fewer populations than we thought.

Network of bog tarns at Waituna Lagoon.

Network of bog tarns at Waituna Lagoon

So, what is the value of this information? We now know where the secure populations of giant kōkopu are in the catchment, so we can carry out more focussed investigations and management.

Cicada. Photo: Andy Hicks.

Cicada at Waituna

The beauty of these sites is that there are few threats to them in their isolated locations. With little habitat change, we anticipate that these populations will be around for a long time.

6 responses to Freshwater survey at Waituna

  1. 

    The ecosystem is really important. We should make every effort to protect the environment and its ecosystem.

  2. 

    While I like to read these blogs as I find them interesting they lack depth. Can I suggest where available a more information link be included for those really interested in the subject. For this blog the acutual reasearch results even if they are only preliminary.
    And why many of the tarns held nothing. Were they poluted and by what. How has the habitat changed. What can be done to restore it. Etc
    Cheers Graham

    • 
      Emily Funnell 07/10/2014 at 4:16 pm

      Hi Graham, Thanks for your interest and comment. You have raised some very fair points. The research is very much in the preliminary stage and are being written up as part of a wider study (the catchment streams were survey earlier on) to understand habitat use of giant kokopu in the catchment. Many of the tarn sites that we surveyed were within conservation estate and in close to pristine condition, so we are not suspecting habitat change at this stage. I haven’t explored the causes of the observed patterns yet, but at this stage I suspect it is related to historic hydrological connnections. Even though giant kokopu are a whitebait species with a migratory life history (larvae rear in the sea and return to freshwater as whitebait), they often form landlocked populations that complete their lifecycle in freshwater. It is possible that the tarns where we found giants had been flooded in the past by high water levels in Waituna Lagoon allowing the fish to populate these sites. In the sites where there were no fish, it is likely that they have been isolated from other waterbodies for much longer than we thought. We will be expoloring geological and LiDar (light detecting and ranging) ground imaging information to see if we can answer these questions.
      In regards to the information linking in the blog posts, I am sure our blog experts will respond to you. Effective communication of science is a constant challenge and an area we are always trying to improve.
      Cheers, Emily Funnell

    • 

      Hi Graham,
      Thanks for your comment. I see Emily has already responded to some of your concerns, which is great. As you can appreciate, the blog is intended to be a once over lightly, that anyone and everyone can understand and enjoy. Too many words put the majority of our readers off. We agree, however, that it is ideal to have more detailed info to link through to (and we do make those linkages when they exist – usually to the DOC website). Unfortunately, not everyone has the time to publish a more detailed account of their work. It is great to see that there is an appetite for this though and, hopefully, it might encourage more people to go the extra mile and provide it! Thanks once again for your comment. We appreciate the feedback.

      • 

        Hi
        Thank you both for your replies. However I do have concern with this statement.
        “Unfortunately, not everyone has the time to publish a more detailed account of their work”
        Can this mean that research carried out in the past, now and potentially in the future is lost and is not been recorded. If so we will never learn cause and effect and what effect our changes in how we look after or abuse our environment make to these places.

      • 

        Hi Graham. Sorry, it probably wasn’t the best way of wording it! To clarify, DOC does record and publish the output of science investigations undertaken by staff (and contractors). You can find this work here: http://www.doc.govt.nz/publications/science-and-technical/ We can’t, however, always make the links to this detailed work on the blog because the timing of our ‘in the moment’ informal stories rarely coincides with the somewhat longer, more formal, science and technical publication process. When I wrote ‘not everyone has the time to publish a more detailed account of their work’ I was thinking about that in-between level of information – more detail about the work, but not necessarily the formal, peer reviewed, final published research findings. I hope that eases your mind a little! Kind regards, Elizabeth