I have a soft sediment sample and I want to calculate some of the common Biodiversity indices (e.g. Shannon's, Simpson's, Margalef's, etc.). Since most of the gastropod shells are empty, can I include them in the calculation or should I just count the ones with the actual gastropods inside?
Dear lolas
In the biodiversity estimation of soft samples, the molluscans empty shells should not be considered. Take the shell with actual gastropod inside. that is the true calculation of biodiversity.
Hi,
I agree with the fact that only occupied shells have to be counted. Indeed, empty shells are present in a place only thanks to local hydrodynamism, and it does not represent the real biodiversity.
Thank you for the replies!
This was my initial thought, since it is common sense, but better to be safe than sorry!
Hi Alexis
Since you are estimating the present-day diversity from a given study area you shouldn´t include empty shells in your data matrix. Shells corresponds to a testimony of recent (or not so!) biological activity, but many times those remains do not belong to your study area. Furthermore, if you are studying soft-bottom samples avoid to use data from incomplete/broken and juvenile specimens unless are sure that they belong to a well-known species. Good look with your work!
All the best, Roberto
It depends on your question! Counting dead, but non-transported shells, is sometimes critical for obtaining a longer-term view of assemblage diversity. Otherwise you may just be measuring a very transient living assemblage. Often live+dead will give you more meaningful data for longer-term questions. I suggest you select a couple of the many papers on "time-averaging" of molluscan assemblages in the paleobiological literature for further information.
Hi,
It could be helpful reading of "Delta-associated molluscan life and death assemblages in the northern Adriatic Sea: Implications for paleoecology, regional diversity and conservation" by Weber and Zuschin (Palaeo3 2013 January 15; 370(C): 77–91)
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India