|Gear and General Techniques|
|Water scavenger beetles are found in virtually every aquatic situation you can imagine. From small puddles to large river margins, they are a common and frequently encountered part of the aquatic macroinvertebrate community in all regions of the world. If you splash around in a nearby pond, you'll find some.
The methods outlined here are meant to go beyond the usual "dip netting" that is generally thought of by my most people for collecting aquatics. These methods focus on collecting the greatest amount of material with the greatest diversity of taxa in the shortest amount of time. When conducting fieldwork, efficiency is important as time is short and the difference between spending 20 minutes or 3 hours at a site can mean visiting fewer sites.
Additional methods that focus on individual niches can be found on the habitat pages.
|Gear: A specialist's "field bag" and what's inside|
|I have developed a standard set of gear that fits in a compact, lightweight field bag that will satify my needs for a typical day in the field. As I do much of my fieldwork under more rugged conditions, some of these tools are not needed for, say, collecting in a backyard pond.|
|1: Field Notebook and pencil. Essential for keeping accurate locality and habitat notes. As my hands are constantly wet and dirty from collecting in water (or rain), water-resistant paper is a must.
2. Collecting bag. A sturdy, water-resistant bag with lots of pockets and room for water. All this stuff fits inside it.
3. Nalgene of ethanol (95%). I collect everything directly into ethanol.
4. Camera. For habitat photos.
5. Compact aquatic net. I took a regular net bag and put it on a rim made of rubber-coated wire that is sturdy enough to keep it's shape, but can be bend into various shapes , as well as fit easily it my bag.
6. Pillow cases (with zipper to keep closed). I use these to collect moss/leaf litter to sift later
7. Vial with label paper. Labels to put into my field vials.
9. Flagging ribbon. Absolutely essential if you're forging your own path. I also use it to mark obscure habitats I want to visit later.
10. Two-way radio. For coordinating group-fieldwork
11. Lots of vials of different sizes
12. Aspirator. The essential field tool!
13. Aspirator de-clogger. A small piece of rubber coated wire that is flexible enough to thread through the aspirator tube, but sturdy enough to push through the offending beetle or seed
14. Paint brushes. For collecting in seeps and flowers
15. Fine and hard forceps.
16. Tea strainers. Also one of my fundamental field tools (I always take a spare). See below method for sploosh and skim.
18. Fixed blade, medium sized knife. Multi-purpose tool for looking in bromeliads, under bark, etc.
19. All-purpose tool (e.g. Leatherman or similar).
20. String. Just something good to have.
21. Gloves. I use these if I'm doing a lot of net or machete work, or if I'm pulling down bromeliads, etc.
22. Basic first aid kit.
23. Insect repellant.
24. Back-up flashlight
|The "Pan & Screen" method|
|The screen and pan method is a simple and extremely efficient technique, and was first pointed out to me by Rob Roughley (U of Manitoba). Place a screen or wire rack over a white or light-colored pan. After collecting a lot of "gunk" and detritus in a pond or stream margin, drain out the water and dump this material onto the screen. As the beetles move around, they will fall through the screen. After a minute or two, you can then simply collect the concentrated beetles in the pan. This avoids having to sift through mud and dead leaves, hunting down each specimen. It should be noted that some of the smaller, less active hydrophilids do not readily fall through the pan as they stay in the leafs and algae. So, some follow-up picking of this material is still needed to get a full sampling. When I'm in a hurry and looking for cheap screen, a flimsy wire cooling-rack works well.|
|The "Sploosh & Skim" method|
|The basic idea is to splash around at the margin of a stream, pond, or marsh, such that the substrate is disturbed and the beetles are dislodged. As many hydrophilids are poor swimmers, they will float to the surface and get caught in the surface tension. I then use a tea strainer to skim off these beetles...since the water drains through, I then aspirate them directly from the strainer. This method is admittedly not good for genera that swim very well, primarily Berosus, Tropisternus and their relatives. Beetles living in these marginal substrates are not well-collected using just a dip net, and so are often more likely to be interesting or "uncommonly collected". It is important to get a strainer with as fine a mesh as possible, as smaller beetles like Anacena and the smaller dytiscids and hydraenids will crawl through coarser openings.|
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