Comparative study of the fatty acid composition of sponges of the genus Ircinia. Identification of the new 23-methyl-5,9-tetracosadienoic acid.

1. The phospholipid fatty acid compositions of the sponges Ircinia strobilina, Ircinia felix, Ircinia campana, Ircinia sp., Spongia tubulifera and Dysidea etherea were studied, revealing the presence, besides other common fatty acids, of considerable amounts (2-5%) of the novel 23-methyl-5,9-tetracosadienoic acid (1). 2. The demospongic acids 5,9-tetracosadienoic acid, 23-methyl-5,9-tetracosadienoic acid (1), and 5,9-pentacosadienoic acid, were particularly abundant in sponges of the genus Ircinia, in contrast to the most common 5,9-hexacosadienoic acid found in other species. These findings are discussed in terms of the taxonomy of the Dictyoceratida. 3. The complete characterization of the novel phospholipid fatty acid 23-methyl-5,9-tetracosadienoic acid (1) is presented.     

The sterol composition of the marine sponge Aplysina (= Verongia) archeri: a comparative study of the Verongidae

1. The sterol composition of the marine sponge Aplysina archeri was studied revealing the presence, besides other common sterols, of considerable amounts (75%) of aplysterol (1), verongulasterol (3), and 25-dehydroaplysterol (4). 2. 24,28-Didehydroaplysterol (2) was not present in the sterol mixture as it was previously reported for the Verongidae. 3. A comparison between the characteristic sterols of the Verongidae was carried out.     

Analysis of temporal variability in the concentrations of some elements in the terrestrial moss Pseudoscleropodium purum

The uptake of contaminants by moss is a complex process that depends on the nature and characteristics of the contaminants and on the physicochemical and biological processes that affect the moss. All of these factors in turn depend on environmental variables that may vary within a short time. It can therefore be assumed that the uptake of elements varies in such short periods that it is very difficult to obtain temporally representative results in biomonitoring studies with terrestrial moss. In order to investigate the temporal variability and the implications that it may have on the interpretation of the results obtained in this type of study, the tissue concentrations of 12 elements were determined in samples of the moss Pseudoscleropodium purum collected from two sampling sites in Galicia (NW Spain), during a long term survey with a high frequency of sampling. The results showed that the concentrations of the elements in the moss varied greatly within very short periods, and that the error associated with the temporal variability in the results was high. In accordance with these findings, and taking into account that the technique enabled contaminated and uncontaminated sites to be distinguished, we recommend that the results of biomonitoring studies should be regarded as qualitative or semiqualitative, rather than attempting to provide absolute data, which may not be temporally representative, and may have a high degree of uncertainty associated with them.