R.W.M. van Soest

Molecular evidence of cryptic speciation in the ''cosmopolitan" excavating sponge Cliona celata (Porifera, Clionaidae)

Over the past several decades molecular tools have shown an enormous potential to aid in the clarification of species boundaries in the marine realm, particularly in morphologically simple groups. In this paper we report a case of cryptic speciation in an allegedly cosmopolitan and ecologically important species-the excavating sponge Cliona celata (Clionaidae, Hadromerida). In the Northeast Atlantic and Mediterranean C. celata displays a discontinuous distribution of its putative growth stages (boring, encrusting, and massive) leading us to investigate its specific status. Phylogenetic reconstructions of mitochondrial (COI, Atp8) and nuclear (28S) gene fragments revealed levels of genetic diversity and divergence compatible with interspecific relationships. We therefore demonstrate C. celata as constituting a species complex comprised of at least four morphologically indistinct species, each showing a far more restricted distribution: two species on the Atlantic European coasts and two on the Mediterranean and adjacent Atlantic coasts (Macaronesian islands). Our results provide further confirmation that the different morphotypes do indeed constitute either growth stages or ecologically adapted phenotypes as boring and massive forms were found in two of the four uncovered species. We additionally provide an overview of the cases of cryptic speciation which have been reported to date within the Porifera, and highlight how taxonomic crypsis may confound scientific interpretation and hamper biotechnological advancement. Our work together with previous studies suggests that overconservative systematic traditions but also morphological stasis have led to genetic complexity going undetected and that a DNA-assisted taxonomy may play a key role in uncovering the hidden diversity in this taxonomic group.

Sexual Reproduction, Larval Morphology and Behaviour in Demosponges from the Southwest of the Netherlands

The reproductive periods of sponge species from the SW of The Netherlands were determined. Morphological characteristics of the larvae of the recently described Haliclona xena and Mycale micracanthoxea are given. More detailed information is included on the previously described larvae of Halichondria panicea, Halichondria bowerbanki, Hymeniacidon perlevis, Haliclona oculata, Haliclona rosea, Acervochalina loosanoffi and Dysidea fragilis. Morphological changes in sponge larvae during their free life are described. Furthermore an overview of known larval descriptions is included along with a discussion of the taxonomic value of larval features.

The Indonesian sponge fauna: A status report

Abstract Snellius-II sponge collecting yielded 355 species (together about 1300 specimens). An illustrated simplified key to the more common reef forms is presented using only field characters. A preliminary taxonomic review of the Indonesian sponge fauna is given based on an analysis of material collected during the Snellius-II Expedition, of older material of the Siboga Expedition (so far largely unpublished), and of data in the literature (most recent dating from before 1935). The Indonesian sponge fauna, which is provisionally estimated to comprise 830 nominal species (obvious synonyms not counted) is compared to the fauna of relatively well-studied areas elsewhere in the Indo-Pacific region and to the West Indian sponge fauna, using numbers of species of each of 188 genera occurring in more than one of the areas concerned. Based on published reports the Australian tropical sponge fauna appears to be dissimilar to that of Indonesia.

Localization and ecological significance of oroidin and sceptrin in the Caribbean sponge Agelas conifera

The Caribbean sponge Agelas conifera was found to produce a mixture of previously described bromopyrrole alkaloids of which oroidin (1) and sceptrin (2) were predominant. This sponge harboured large populations of heterotrophic bacteria but no photosynthetic symbionts (cyanobacteria). However, 1 and 2 were not associated with the bacteria but with the sponge cells as shown by their distribution in enriched cell fractions obtained by differential centrifugation and Ficoll density gradients. Spherulous cells, found in great abundance in the sponge ectosome, were assumed to be involved in the production of 1 and 2. The target compounds were detected, although in small amounts, in short-term cultures of sponge cells, validating the possibility of a continuous cell culture source. Laboratory assays showed that organic sponge extracts affected the behaviour of the coral Madracis mirabilis in causing closure and retraction of the polyps at concentrations of the combined compounds 1 and 2 (1:3.3) as low as 0.7 mg/l (0.0125% of the concentration in whole sponges). At higher concentrations (1.4 mg/l) no recovery of the polyps occurred. The extracts, at almost natural concentrations of 1 and 2, deterred feeding by the predatory reef fish Stegastis partitus, supporting other reported research. In field experiments, wounding induced a sharp increase of 1 and 2 in the sponge tissues but prolonged predator exclusion by caging and forced confrontation with coral neighbours did not yield measurable changes in 1 and 2 concentrations. All sponges were found to release measurable amounts of bromopyrrole alkaloids in seawater conditioned for 30 min. Crude and fractionated sponge extracts and pure sceptrin (2) were active against bacteria, yeast and filamentous fungi. Taken together, these results support a role of oroidin (1) and sceptrin (2) in defence mechanisms against predators and possibly against space competitors and invading and fouling organisms.

Sub-rubble communities of Curacao and Bonaire coral reefs

The distribution and abundance of sessile organisms under coral rubble has been studied at Bonaire and Curaçao, Netherlands Antilles. Species richness under rubble is extremely high with at least 367 species of which sponges, tunicates and bryozoans are the most important. Shallow sub-rubble communities can be considered refuges as the majority of these species are crypt-obligate. Sub-rubble communities may also have a preserve function for sponges, but do not harbour enough corals to ensure a quick coral recolonization of the reef surface after a major disaster. Cryptic community composition is affected by depth and pollution, and differs substantially between the two neighbouring islands, possibly as a result of different bottom characteristics. Biomass of the sub-rubble communities may contribute considerably to total reef biomass. Diversity varies inversely with increased depth and increased rubble size, possibly indicating abiotic control (e.g. physical disturbance by wave action and reef slope substrate collapse).

Nitric oxide reduction and carbon monoxide oxidation over carbon-supported copper-chromium catalysts

Abstract Carbon supported copper-chromium catalysts are shown to be very active for both the reduction of nitric oxide with carbon monoxide and the oxidation of carbon monoxide with oxygen. Mixed copper-chromium oxide active phases have good activity in the simultaneous removal of nitric oxide and carbon monoxide from exhaust gases. The influence of several catalyst variables has been investigated. The activity per volume of catalyst increases with increasing loading, while the intrinsic activity shows a maximum around C/M=100−50. An optimum catalyst for nitric oxide reduction and carbon monoxide oxidation has a copper/chromium ratio of 2/1. The apparent activation energy for the carbon monoxide oxidation over carbon supported copper-chromium catalysts is 77 kJ/mol, suggesting that the CuO bond rupture is the rate-limiting process. The reduction of nitric oxide takes place at higher temperatures. Since all catalysts have a low selectivity for molecular nitrogen formation at lower temperatures, the dissociation of nitric oxide is probably rate determining, resulting in a slightly reduced catalyst system. In an excess of carbon monoxide the reaction is first-order in nitric oxide and zero-order in carbon monoxide. Moisture inhibits the reaction by reversible competitive adsorption, whereas carbon dioxide does not. Oxygen completely inhibits the reduction of nitric oxide due to the more rapid reoxidation of the catalytic sites compared to nitric oxide. Therefore, the reduction of nitric oxide takes place only when all oxygen has been converted and, hence, is shifted to higher temperatures. As a possible consequence, the production of nitrous oxide is reduced. Nitric oxide and molecular oxygen react preferentially with carbon monoxide, so, in an excess of oxidizing component, gasification of the carbon support occurs at higher temperatures after carbon monoxide has been completely consumed.

BIOACTIVE ALKALOIDS FROM THE TROPICAL MARINE SPONGE AXINELLA CARTERI

Abstract Analysis of the tropical marine sponge Axinella carteri afforded six unusual alkaloids, including the new brominated guanidine derivative 3-bromo-hymenialdisine. The structure elucidation of the new alkaloid is described. The alkaloid patterns of sponges collected in Indonesia or in the Philippines were shown to be qualitatively identical suggesting de novo synthesis by the sponge or by endosymbiontic microorganisms rather than uptake by filterfeeding. All alkaloids were screened for insecticidal activity as well as for cytotoxicity. The guanidine alkaloids hymenialdisine and debromohymenialdisine exhibited insecticidal activity towards neonate larvae of the polyphagous pest insect Spodoptera littoralis (LD50s of 88 and 125 ppm, respectively), when incorporated into artificial diet and offered to the larvae in a chronic feeding bioassay. The remaining alkaloids, including the new compound, were inactive in this bioassay. Cytotoxicity was studied in vitro using L5178y mouse lymphoma cells. Debromohymenialdisine was again the most active compound (ED50 1.8 μg/ml) followed by hymenialdisine and 3-bromohymenialdisine, which were essentially equitoxic and exhibited ED50s of 3.9 μg/ml in both cases. The remaining alkaloids were inactive against this cell line

Notes on variation of diatoms and silicoflagellates in the South Atlantic Ocean

Abstract This paper contains the results of studies on the seasonal and latitudinal variation of certain phytoplankton organisms from the Southern Atlantic Ocean and the adjacent sector of the Antarctic Ocean, based on samples taken by the “Willem Barendsz” Cruise 1959–1960. Particularly the study of the diatoms Fragilariopsis kerguelensis, Coscinodiscus lentiginosus, C. minor, Asteromphalus hookeri and the silicoflagellate Distephanus speculum has revealed new and interesting facts, concerning the theory of Wimpenny (1936, 1946, 1966) of the influence of temperature on the size variations of planktonic diatoms, although no definite support or negation of this theory could be given. Next to temperature, certainly other factors as the population density and the nutrient content of the seawater have been found to influence the size of diatoms. No support has been found for the theory that the intensity of grazing might be responsible for size variations in diatoms. The hitherto known range of Fragilariopsis kerguelensis has been extended to 30°N; a more or less continuous series of samples from the Subtropical Convergence at 40°S to 30°N showed the species to be scarce but nearly always present in this area. Asteromphalus heptactis, a (6+1) rayed form, could be synonymized with A. hookeri, as it proved to be only an ecotype or morph of this species. The (3+1) rayed form of A. hookeri recorded in this paper is new to science.

Isomalabaricane-type compounds from the marine sponge Rhabdastrella aff. distincta.

Fractionation of the marine sponge Rhabdastrella aff. distincta led to the isolation and characterization of four new isomalabaricane analogues, isogeoditin A (1), 13-(E)-isogeoditin A (2), isogeoditin B (3), and 22,23-dihydrostellettin B (4), along with seven known isomalabaricane derivatives (5-11). Methylation of 10 and 11 afforded methyl esters 12 and 13. The structures of compounds 1-4 were determined on the basis of spectroscopic data analysis. All compounds were tested against a small panel of human tumor cell lines.

Phylogenetic Exercises with Monophyletic Groups of Sponges

The classification of the Porifera is critically evaluated using cladistic principles. The (syn-)apomorphic characters and character states are established for 34 groups of Porifera which are generally accepted as monophyletic. These characters/states are compared with the currently accepted classification of Hartman (1982), resulting in the conclusion that there are many non-parsimonious homoplasies included. Two consecutive attempts to amend this are presented. The first consists of a self-constructed strictly cladistic classification characterized by the assumption of many assumed losses. The second is a computer-based analysis characterized by a neutral construction of a classification with the least number of assumed homoplasies.