Saturday, June 21, 2008

Back to the roots - Chiemgau impact

This is a bit off topic, but since I am in holidays...:
The chiemgau impact is a controversially discussed, postulated meteorite impact, located in the heart of my Bavarian home, the Chiemgau. The change log for the german Wikipedia entry has more than 500 (!) pages and shows the quality of the controversy.
One of the pro arguments was the discovery of some strange, finger-print like looking surfaces on stones collected in the Chiemsee, which were identified as 'regmaglypts' (surface ablation structures produced by partial melting of the meteorite surface when it passes the atmosphere) by the impact advocates.
I found this explanation very unlikely, as regmaglypts are extremely rare, and such ornamented stones are very common in this lake. The carbonate rich waters of the Chiemsee favors calcareous algae such as Charophyta (v) or Cyanobacteria. The bottom river Alz which origins in the Chiemsee is covered near Seebruck by recent calcareous Oncoids (e.g. Rott, 1991, H├Ągele et. al, 2006). Further, similar structures are quite common and well known at the Bodensee, Attersee and other alpine lakes area where they are known as 'Furchensteine'.
Therefore a biogenic origin of those 'regmaglypts' seems to be more likely, most probably produced by endolithic cyanobacteria. I reported my suspect, and my hint was frankly published on their homepage ... but they didn't really believe.
I currently am visiting my home village and last rainy Tuesday I had the opportunity to visit the lake Chiemsee and could collect and observe a large number of these Furchensteine near Chieming. Here they are really very common, I could count up to 40 of them per square meter.
I found dry specimen at the lake beach as well as some fresh, in-situ exemplars in the lake itself covered by water. Those Furchensteine which are covered by water, show a cauliflower like structure, made up by some kind of organic coating, most probably algae. After scratching off this coating, the typical finger-print structures appear.
For me there is no doubt that these structures are biogenic. If you want to see more pictures, I have uploaded some here.

Tuesday, June 17, 2008

What LSIDs are good for

Recently, I found David Shorthouses blog post on LSIDs (Life Science Identifiers) where he reports that apparently several LSIDs from different data sources exist for a distinct (spider) taxon. His intended use for LSIDs was to use them instead of the real taxon names and to "confidently link names with other sources of information such as information about the type specimens, gene sequences, synonyms, specimens etc". But for this purpose he concluded LSIDs are useless without a centralized identifier registry which ensures that a taxon name has only one LSID.

Well, replacing taxon names by unique identifiers is of course not the most obvious usage of LSIDs. LSIDs are only useful to persistently link to a electronic ressource and are not suitable to link to an abstract entity such as a taxon name. Instead, LSIDs link to a set of metadata, which contains the information which was considered to be useful by a LSID authority. Thus, LSIDs for taxon names link to nothing more than to the electronic resource (metadata, data sheet) which represents the LSID authority's concept of this taxon (btw.: a very interesting article on the whole complex of taxon names, identifiers, authorities, 'real taxonomists' and 'name users' is the Nature paper written by Nimis (2001): A tale from Bioutopia.).

LSIDs are however extremely useful for taxon names when they link to an electronic ressource which serves as authoritative record for this name. Especially LSIDs for newly assigned names which are officially registered by the ICZN in ZOOBANK can serve as citation for the name. This is similar to the usage of DOIs for scientific primary data. R.Pyle for example linked his newly assigned fish names to ZOOBANK records by LSIDs in his recently published paper. An impressive demonstration how useful LSIDs for taxon names can be.