Ten brominated alkaloids, 6-bromo-2-(1,1-dimethyl-2-propenyl)-1H-indole-3-carbaldehyde (1), N-(2-[6-bromo-2-(1,1-dimethyl-2-propenyl)-1H-indol-3-yl]ethyl)-N-methylmethanesulfonamide (2), deformylflustrabromine (3), flustrabromine (4), (3aR,8aS)-6-bromo-3a-[(2E)-3,7-dimethyl-2,6-octadienyl]-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]-indol-7-ol (5), flustramine C (6), dihydroflustramine C (7), flustramine A (8), flustramine D (9), and flustraminol A (10), and the diterpene 4,6-bis(4-methylpent-3-en-1-yl)-6-methylcyclohexa-1,3-diene-carbaldehyde (11) were isolated from the dichloromethane extract of the North Sea bryozoan Flustra foliacea. Of the 10, four (1, 2, 3, and 5) represent new natural products. The structures of all isolates were elucidated by interpretation of their spectroscopic data (NMR, MS, UV, and IR). For compound 4 complete (13)C NMR data are reported for the first time. Compounds 3 and 6-8 were tested on voltage-activated potassium and sodium channels. Flustramine A (8) shows an unspecific blocking activity on Kv1.4 potassium-mediated currents.

The North Sea bryozoan Flustra foliacea was investigated to determine its secondary metabolite content. Gas chromatography-mass spectrometry analysis of a dichloromethane extract of the bryozoan enabled 11 compounds to be identified. Preparative high-performance liquid chromatography of the extract resulted in the isolation of 10 brominated alkaloids (compounds 1 to 10) and one diterpene (compound 11). All of these compounds were tested to determine their activities in agar diffusion assays against bacteria derived from marine and terrestrial environments. Compounds 1, 3 to 7, 10, and 11 exhibited significant activities against one or more marine bacterial strains originally isolated from F. foliacea but only weak activities against all of the terrestrial bacteria. By using the biosensors Pseudomonas putida(pKR-C12), P. putida(pAS-C8), and Escherichia coli(pSB403) the antagonistic effect on N-acyl-homoserine lactone-dependent quorum-sensing systems was investigated. Compounds 8 and 10 caused reductions in the signal intensities in these bioassays ranging from 50 to 20% at a concentration of 20 g/ml.

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Recent studies on meiofaunal and nematode communities have focused on soft sediments in streams, lakes and marine environments. Despite a large number of studies dealing with periphyton, meiofaunal and nematode communities, on littoral hard substrates in lakes have not yet been investigated in detail. Therefore, epilithic communities with particular emphasis on nematode species composition, were analysed in 17 Swedish lakes differing greatly in size, depth, trophic status and epilithic biomass. Nematode abundance ranged from 2.3 to 161.5 cm −2 , and the abundance of nematodes relative to total meiofauna ranged from 20 to 77% (mean 53%). Fifty-eight nematode species were identified; species numbers varied from eight to 34 species per lake. The dominant species were Rhabdolaimus aquaticus, Punctodora ratzeburgensis, Eumonhystera dispar and Crocodorylaimus flavomaculatus. Deposit feeders dominated (71% of total fauna), followed by suction feeders (14%), epistrate feeders (12%) and chewers (3%). Of 3624 nematodes examined, 54% were juveniles, 35% females, 6% males and 5% gravid females. Multivariate analysis of the nematode species composition revealed significant differences in the community structures among lakes. This is the first study to show that meiofauna is a numerically abundant group within littoral periphyton communities in lakes, with nematodes representing the dominant group.

Several brominated indole alkaloids and a diterpene (1-7) were isolated from the dichloromethane extract of the North Sea Bryozoan Flustra foliacea. Alkaloid 4 is a new natural product, whose structure was elucidated by interpretation of spectroscopic data (NMR, mass, UV, and IR). All compounds were tested for their in vitro affinity towards the alpha4beta2* and alpha7* subtype of the neuronal nicotinic acetylcholine receptor (nAChR) using radioligand binding assays. Deformylflustrabromine (3) and deformylflustrabromine B (4) were shown to have affinities in the lower micromolar range for nAChRs, differing in their subtype preference.

This chapter is an attempt to bring together the studies of nematode diversity in terrestrial, freshwater aquatic and marine environments, and to synthesize these into some sort of general hypotheses. Such hypotheses can then be used as the bases for a range of other scientific activities, including biomonitoring and hypothesis testing. The effects of many of the variables in studies of nematode diversity, such as methods used, resolution or scope of studies, and measures of diversity are discussed first. With this background, studies on nematode diversity are then summarized and compared at a general level. Finally, hypotheses of the general patterns and processes of nematode diversity are discussed. These general patterns form the natural background for biomonitoring: to evaluate any effect of an environmental change one must know the situation expected without the change, including the expected magnitude and direction of the effects of environmental change.

Meiofaunal organisms in the periphyton of stony hard-substrates (epilithon) were studied in three Swedish lakes with different trophic states (oligo-, meso-and eutrophic)

In Lake Constance, Eurasian bream Abramis brama (L.) spawn in very shallow littoral areas by the beginning of May. They attach their adhesive eggs to pebble and cobble substratum at \40 cm depth. Increasing water levels before spawning inundate bare substratum to which bream eggs may attach better than to deeper substratum covered by epilithon. Consequently, the water level increase prior to spawning should determine the amount of pristine spawning substratum available to bream and thus influence their breeding success. In order to test this hypothesis, the influence of hydrology and climate on the abundance of age-0 bream was combined with the results from field investigations on the egg survival and abundance of age-0 bream. A strong positive correlation between the mean water level increase during the spawning season of bream (April-May) and the abundance of juvenile bream was found. In contrast, the absolute water level during spawning and during the nursery stage in summer, the cumulative temperature during the egg, larval and juvenile stages and two North Atlantic Oscillation (NAO) indices did not affect the abundance of juvenile bream. The field investigations confirmed that bream eggs attach better to and have higher survival rates on bare substratum than on substratum with epilithon cover. Accordingly, eggs within a spawning habitat of bream were most abundant between 10 and 20 cm depth, where the epilithon cover was lower than at depths exceeding 30 cm. The results of this study confirm an adverse influence of epilithon cover on the attachment and subsequent survival of bream eggs and emphasize the importance of spring inundations for the successful breeding of the bream.