[Annelida] problems in Sprirorbids identification and counting

Barbara Mikac via annelida%40net.bio.net (by barbara.mikac from cim.irb.hr)
Wed May 21 03:22:12 EST 2008


Dear colleagues,

I have doubts and difficulties with determination and counting of the
Sporobidae in my research so I would like to ask you for the advice on how
to solve these problems.

I'm analyzing polychaetes from hard bottom from the northern Adriatic Sea
from 1,5 m, 5 m and 25 m depths. On every depth three replicates are taken
- 10x10 cm square. In the 1,5 m samples, and in smaller number also on 5
m, there are many many serpulids, attached on the algae. The algae are
mostly Corallina sp., Flabelia petiolata and Padina pavonica, but there
are also other algae. And among them, on Corallina, the abundance of
serpulids is the biggest, since this one is, due to it's complex
structure, offering the biggest surface for the attachment. These
serpulids are too small to remove each of them from the algae and
determine because they are too fragile and get easily broken, and even
only to count them it would take too much time (if possible at all).

Can you maybe recommend me some way to solve this problem? Is there some
method to estimate the number of Serpulids and the species in the whole
sample (withouth looking through each of them), by counting them only in
one part? Can you recommend me some literature?

I came to the idea to count the number of serpulids in one part of the
sample, than weighting this part and by weighting the whole sample try to
estimate how many of serpulids are in the whole. But I suppose this would
be wrong because peaces of algae thalus in the sample are of different
sizes and sometimes containing only 5 serpulids, sometimes 40, so
generalization for the whole sample is not possible. Even more considering
the small size and equivalently small weight of Serpulids in comparing to
the algae on which they are attached.

I certainly wouldn't like to neglect it and just say in my future paper
that serpulids were not taken into consideration (as I've seen in some
papers), because considering their number they are obviouly the  most
abundant family in the samples (for the number of species I wouldn't know)
so their importance in the community is big.

Thank you very much for your help!

Many greetings,
Barbara Mikac

____________

Barbara Mikac, M.Sc.
Marine Research Centre
Rudjer Boskovic Institute
G. Paliaga 5
52210 Rovinj
Croatia
tel: 00385 52 506065
fax: 00385 52 506065
e-mail: barbara.mikac from cim.irb.hr



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