ESTIMATINGPOPULATION SIZE Arenicola marina (lugworm)

1. ESTIMATINGPOPULATION SIZEArenicola marina (lugworm) Arenicola marina has size between 25 and 36 cm(Tyler-Walters, H. 2001). Live along shores in Western Europe in 20-40 cm deep in U/J shape burrows in(Tyler-Walters, H. 2001). Body is cylindrical and consist of thorax and abdomen(Tyler-Walters, H. 2001). A. marina ingest organic material(Tyler-Walters, H. 2001). They are pink, red and green in colour (Tyler-Walters, H. 2001). http://www.arkive.org/lugworm/arenicola-marina/info.html

2. Method 1: Mark and Recapture Used when you cannot get all in a population at a specific time when the site is visited (Greiser &Faubel, 1992). Identify area and size where species mostly occur (coast). A random sample of A. marina is captured (not injured) with a garden fork (Greiser &Faubel, 1992). Sand was broken down and sorted by hand using gloves. Marked and releasednot toxic substance(Greiser &Faubel, 1992). After redistributed itself, a second random sample is taken (Greiser &Faubel, 1992). The percentage that was marked in the recapture sample is equal to the percentage of the population that was marked in the beginning (Greiser &Faubel, 1992).

3. Example: 5 A. marina are marked and 1 out of 10 recaptures has the marked, 10% of population is marked (McLuscy et al., 1983).Thus if 5 animals equals 10% of the population, then population consists of 50 (McLuscy et al., 1983). Many recaptures gives a small population and a few recaptures gives a large population (McLuscy et al., 1983). ProblemsAll the individuals in the population have an equal probability of being captured (McLusky et al., 1983).Some of the individuals after been captured may avoid the traps after that, or some may be attracted to the traps (McLusky et al., 1983).

4. Method 2: Burrow counting Use transects to estimate the total number of burrows (Flach & de Bruin, 1993). Transects is a sample unit where the length is greater than the width (Flach & de Bruin, 1993). Use belt transects (Flach & de Bruin, 1993). Use large enough area and also different areas randomly (Flach & de Bruin, 1993). When burrow opening is in the range of the belt it is counted, otherwise not (Flach & de Bruin, 1993). Get the total number of burrows in the the population from the average number of burrows per transect and the total area of the population (Flach & de Bruin, 1993).

5. For both methods mentioned above to work best the population must be isolated from other populations and there must be no emigration, immigration, death and births.(Flach & de Bruin, 1993). http://content8.eol.org/content/2009/07/30/01/89775_large.jpg

6. References Flach, E. C., de Bruin, W. (1994). The activity of cockles, Cerastodermaedule (L.), and lugworms, Arenicola marina L., make Corophiumvolutator (Pallas) more vulnerable to epibenthic predators: a case of interaction modification. J. exp. mar. Biol. Ecol. (in press) Greiser, N. & Faubel, A., 1992. Biotic factors. In Introductionto the study of meiofauna (ed. R.P. Higgins and H. Thiel), pp.79^114. Washington DC: Smithsonian Institution Press. Macintosh, D. J., 1988. The ecology and physiology of decapods of mangrove swamps. Symp. Zool. Soc. Lond. 59:315-341. McLusky,D.S.,Anderson,F.E.&Wolfe Murphy,S.,1983.Distribution and population recovery of Arenicolamarina and other benthic fauna afterbaitdigging.MarineEcologyProgressSeries,11,173^179. Tyler-Walters, H. 2001. Arenicola marina. Blow lug. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. (November, 2002) http://www.marlin.ac.uk/species/Arenicolamarina.html http://content8.eol.org/content/2009/07/30/01/89775_large.jpg http://www.arkive.org/lugworm/arenicola-marina/info.html