Recently I subitted a query to the annelida discussion group (see links page). The responses are following my original letter. **** ORIGINAL LETTER **** Hi everyone, For my PhD I'm working on some large beachworms (0.3 - 1.5 meter) and have to work out some kind of replicatible sampling strategy to work out population size, density etc. They live in the subtidal to swash zones on sandy surf beaches, and i'm working on the east coast of Australia, around Brisbane. Because of their size and mobility, standard cores won't work. While taking a front end loader onto the beach and scooping up the beach and sifting it would work, somehow it doesn't seem feasible!! The only method I have seen to actually measure abundance/population size/density has been to attract the worms to the surface using burley (oily shark skin) and count the number of emerged worms. There are a couple of problems with this method: It's hard to distinguish the different species. It assumes 100% emergence. It assumes all the worms emerge at the one point in time (and stay emerged long enough to count). Commercial worm fishermen catch the worms by hand (i.e., once emerged, are pulled out by hand) I can look at fishermens catches, times fished etc, however the fishermen are selective for larger worms, and particular species. Again the same problems apply. One idea i am playing with at the moment is using photography to document emergence, and then the counting thing won't be a problem and maybe (i haven't got my hopes up) i can work out species as well. If anyone has any great references/ideas/methods/comments for sampling these critters (or even anything like them!), can you please PLEASE reply. If you don't have answers, but have ideas please tell me! I REALLY NEED AND WOULD APPRECIATE SOME FEEDBACK ON THIS! Thanks in advance and happy worming! Matthew **** ANSWERS **** only suggestion - if these giants build permanent and single vertical burrow in sediments per specimen, it's possible to base estimate on density of burrows. Have you heard about drumming? Instead of bait, you stomp your feet rhythmically in the sand and the worms will come boiling out (hopefully not boiling mad!) I was introduced to this method by Dr. Ralph Brinkhurst a number of years ago. It works like a charm on all species in the area. I would suggest putting down area markers, (25 mm pvc pipes joined to make a 1 m-square frame), then try drumming. When the worms are up, photograph and grab some for identification. I wonder if heavy rock music would work? I normally live in Brisbane, and am familiar with the animals you wish to study. I am also a polychaete taxonomist, or was for about 15 years in the Northern Territory. My experience with identifying members of the Onuphidae suggests that it would be difficult to determine species accurately by any remote method. This is complicated by the fact that morphological changes in some species from juvenile thru subadult to adults are quite dramatic. As documented by Hannelore Paxton. Why don't you try simple capture- mark- recapture techniques as a method of estimating population abundances? From what I have seen it is possible to keep these animals alive quite easily after capture. I would mark them by removing a number of the parapodia from one side of the body, say all the left side parapodia from segments 7-12? and then release them again. The removal of a few parapodia is not going to affect them very much, these sort of injuries are quite common in the wild. With practice you could remove these under binocular microscope with a pair of iris scissors relatively easily. If the animals are too frisky to handle during the removal of parapaodia, they can be slowed down with a very small amount of clove oil in seawater. Too much and they might not recover from it. Obviously if other people are catching them in your study area you want to recapture soon after release -the next day? Doing this would mean that you could estimate abundances and densities for each the species in your area of study. I am presently in Java until early July, but am happy to spend a little time to help you work out how to mark these animals when I get back to Brisbane, although I only have 3 weeks before going to Irian Jaya. I would capture using baits, and would take care to ensure that your baits and positions of the baits were the same each time. The only problem is determining how far these animals are attracted to baits and how quickly they can move to a bait from some distance away (densities). Perhaps once you have made an estimate of the total abundances in an area thru capture mark recapture, you could subsample small areas where you do sift the substrate for them? You may already have thought of this, and ruled it out, but I would give it a go. In Malaysia the fishermen use the pulp of coconut meat to attract worms to the surface. These are Dioptra and large enough for bait. Terrestrial types (in the past) have used a dilute solution of formalin to get earthworms to leave their burrows. Not sure how environmentally approved that would be today, but it gets the worms! Ask Hannelore what methods she used. All I can come up with at the present time. I have a similar problem with sampling for compost worms in a waste management sytem. Just a few thoughts 1) digital photography ( time lapse) 2) real time video 3) infra red detection ? 4) destructive sampling (cores, bob-cat or mini excavator!) Your spacial variable is a major problem, ie what area did the worms come from. You might consider marking the worms with a radioactive tracer. This has been attempted in earthorwms. You may find out how far the worms wander. Just a few thoughts lucky guy, the worms I sampled during my Phd had a size of several mm :-) Just a silly idea: is it possible to mark the worms in any way when emerged? Than you could use some catch/re-catch techniques to estimate density. Maybe yellow ribbons, small bells... ;-) Good luck! We have the same problem here in Rimouski with the large Nereis virens, we use a quadrat in wood (1 square meter) and we dig to 45 centimeter in the sediments for catch all the nereis (small mean and big). An other method is take a photography of the square area (for nereis we count the hole) you can use also a box from a usnel box core (we put in the sediment and we seive on the 1 mm mesh seize and probably you have a good representation of the population. The problem with large species is you need a sampler (quadrat) with the same size or more that our big species. Sorry for my english, cause i am french canadian. We publish a paper on the distrivbution of Nereis virens and Nephtys caeca in Marine Biology in 1990: Miron, G and G. Desrosiers, 1990. Marine biology 105, 297-306. Boy, I do not envy you in the least. I work with Streblospio benedicti which is very small and have had to learn how to color them and keep them living. This may be possible for a mark and recapture type of experiment if these worms are hardy. It sounds like they are. My guys are extremely tiny and fairly sensitive. I was doing research on the worm's response to differing concentrations of food by counting the numbers that responded to cores of different sediment mixtures. I have done both field and lab experiments to investigate my question. I had to color the worms to be able to track their movements within my lab experiments. If you are interested in specific protocols, please let me know. I am presently in the process of writing my thesis for my master's and hope to be done by summer. This page was last updated on the 6th June, 2000 This site is maintained by me (Matthew) This webpage was made by Matthew O'Brien Click on the link for more information and other examples of my work.