I just returned from a busy but fun filled week on the BIObus at the Pinery Provincial Park. The main objective was to sample aquatic invertebrates and compile a bio-inventory for the Ausable Bayfield Conservation Authority (ABCA). If you’ve been reading my earlier blogs you know that I’m keen on spiders, and fortunately, I was able to collect some interesting spiders in the ABCA. One unusual spider I found was the orb-weaving Arrow-shaped Micrathena (Micrathena sagittata).
Although I was able to squeeze in some spider searching, most work days were spent sampling aquatic invertebrates. Two of the collection methods we used are called the plankton net and the S.P. (Schindler-Patalas) trap. Both of these traps are primarily used to capture zooplankton which is a group of tiny animals that live in the water and drift with the current. Zooplankton are so small that they’re invisible to the human eye. To get out in the water, my colleague and I rented a canoe and paddled along the Old Ausable Channel in the Pinery. After a few minutes of leisurely paddling, we threw the plankton net behind us and paddled for three minutes. The conical net collects zooplankton in a plastic jar and since the net is a mesh material, most of the excess water can drain out. We then drag the net back in and try to transfer all the zooplankton (which we can’t actually see) into a jar of ethanol. We repeat this process three times and if we’ve done everything right, we should see zooplankton under the microscope when we return to BIO.
With the plankton net, we took a horizontal sample of the channel. But with the S.P. trap, we take a vertical sample of the channel. What we did is find a spot that is comparatively deep, and then we slowly fed the rectangular S.P. trap down into the water until it reached the bottom – counting the meters of rope let out as we go. The lid and bottom of the S.P. trap are hinged so that they will open while lowering the trap and close while raising the trap. This allows water to pass through the box so it can descend in a fairly straight fashion. Once we’ve hit bottom, we slowly drag the trap back up, this seals the top and bottom panels creating a very accurate and consistent volume of water sampled. Pulling the trap up is pretty easy, except for when it comes above water; then it weighs a plank-ton! Again excess water drains out through a mesh sock, the sample with microscopic zooplankton is placed in a jar of ethanol, and this process is repeated three times.
Despite being mainly concerned with aquatic invertebrates, we did quite a bit of sampling for terrestrial invertebrates. Unlike the super scientific plankton tow and S.P. trap, we did this part with regular dry mustard. The reason we use mustard is that it irritates the skin of terrestrial invertebrates like worms. In an attempt to get away from the irritation, they crawl to the surface where we can easily collect them. To do this type of collecting, we bring with us a square wooden plot which we place on the ground. If it’s present, we find a place with thick leaf litter and place the plot down; removing leaves and vegetation until the soil is exposed. After that, we use a trowel to loosen up some of the soil so it’s easier for the worms to move to the surface. We then pour a previously prepared mustard solution into a watering can so we can control our pours better. After sprinkling some mustard solution onto our plot, we collect any worms or other invertebrates for 15 minutes. Following this we pour some more mustard and collect for another 15 minutes. The inverts are stored in a jar of ethanol and taken back to the lab for some DNA barcoding!
Thanks for reading,