Upper River Livet invertebrate sample

A couple weeks ago we collected an invertebrate sample from the middle reaches of the Livet; this week a sample was taken from further upstream, well above Tomnavoulin at Allanreid. I haven’t really had a proper look at the Livet in the summer (to be corrected this year) but it was obvious from the coating of phytoplankton (algae) on the rocks that it was chemically richer than many other Spey tributaries. In the faster flowing water there was less algae and an invertebrate sample could be taken without the net becoming clogged with algae.

Plenty fish could be seen in the Livet, but then it is one of the best tributaries of the Spey, the expectation should be to see an abundance of fry and parr in the Livet. At this time of year it can be hard to avoid the fry with the sampling net but we managed to rescue five from the bucket before we headed back to the office so sort through the sample. Michael, one of our summer students did nearly all of the sorting and all the identification. It was obvious that he was regretting showing such an interest in the subject in his first few days as the sorting tray was teaming with life!

By the end of day two the sample was sorted, see picture below.

River Livet upper sample: clockwise from top left, caddis, stoneflies, mayflies and Diptera etc

River Livet upper sample: clockwise from top left, a) caddis, b) stoneflies, c) mayflies and d) Diptera, worms etc

In total there were over 2800 specimens counted and identified, the most by far that we have found from a Spey site. Invertebrate sampling is quite seasonal as some species hatch others appear. Over 300 Ephemerillidae nymphs (Blue winged Olives) were present, They have only just started to appear in samples as they overwinter in the egg stage. There were over 1200 mayfly nymphs in total and nearly 900 stoneflies, including a few of the large species Perla bipunctata. Caddis flies were less numerous than at the Castle Grant site on the mainstem but there were still over 200.

We scored this sample using the British Monitoring Working Party (BMWP) system, the score being 164. The score at the lower site was 127, combined with much lesser abundance. There could be some sort of impact affecting the Livet further downstream, although both scores were good (generally a score over 100 is considered good).

This sample  turned out to be quite a marathon to sort and identify but it does show the productivity of a burn like the Livet. There is a more than ample supply of invertebrate food to support a high juvenile population. Comparing SEPA results from the Livet from the mid 2000s it is clear that we found vastly more in our samples than recorded by SEPA.

All of the samples examined so far have been good, but all have been from the mainstem or productive tributaries, the next one will have to be from a less productive site for comparison.

A big thanks to Michael for sticking with it and sorting this sample. All good experience for your future career!

 

 

There are 4 comments for this article
  1. Iain Ogden at 11:49 am

    If the upper Livet is chemically richer would this be reflected in the ease to electrofish? i.e. would an ordinary sized anode work effectively here?
    And what’s the source of this increase in chemicals, is it natural geology or man-made?

    Whatever ….interesting data as usual,
    regards, Iain

    • Brian Shaw Author at 1:09 pm

      Hi Iain,

      The higher conductivity is largely natural with more alkaline geology in the area. There are some outcrops of limestone in the Livet/Avon catchment, as well as sandstone hence the higher mineral content of the water.
      When I checked the database I could see that the conductivity ranged from 50 to 100, considerably higher than the Allt Ruadh the other day. Electrofishing with the standard anode works very well at that range of conductivity levels. We did a quick test electrofishing at the Corrie Burn the other day, the conductivity there was just under 200; again largely natural but farm run-off or even septic tanks can all lift the readings.
      You would be more than welcome to come out for a day electrofishing with us this summer.
      Best regards
      Brian

      • Iain hall at 12:14 pm

        Fascinating stuff. Being actually able to refer back and compare previous survey results is very encouraging, particularly to see what appears to be very healthy growth of broad populations of “beasties” . I am now an avid reader of your blog and will be encouraging my local fishery board to publicise more of this material. ( maybe I just don’t see it!) Do you study what healthy parr are actually eating at different times of years. The sacrifice of a FEW parr to know this would be useful provided we humans then use said data well to help conserve the natural balance of river environments.
        Iain

        • Brian Shaw Author at 7:28 pm

          Hi Iain,

          Thank you for the positive comments, makes it all worthwhile! I have always been interested in the invertebrate population especially linking all aspects of the ecology together. We haven’t looked specifically at parr diet but there are lots of old studies available which show that the diet changes seasonally depending on the availability of prey. However I do recall one particularly plump parr in Ayrshire that we had sampled as part of a study on female hormone levels in freshwater fish. The stomach contents of that fish consisted entirely of simulidae larvae (Black fly larvae). I don’t recall seeing simulidae mentioned as a major part of salmonid diet but where they are present they are often abundant and accessible. Maybe that fish had specialised on them? We will continue to publish invertebrate results as they are available but right now we are full time on the fish surveys.
          Best regards
          Brian Shaw

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