Etude expérimentale de la ponte chez trois espèces de copépodes pélagiques (Centropages typicus,Acartia clausi et Temora stylifera)

Egg-laying of 3 common copepod species from the Gulf of Marseilles (Centropages typicus Kröyer, Acatia clausi Giesbrecht, Temora stylifera Dana) has been studied under various trophic conditions, at different periods of the year. The role of phytoplankton abundance in the induction and importance of egg-laying is indicated. The specific quality of the algal suspension used for feeding affected also fertility. A seasonal variation in the importance of egg-laying is established. Some observations are made on egg deposition and development.     

Les Silicoflagellés du Golfe de Marseille

A study of the Silicoflagellates of the Gulf of Marseilles was carried out using water samples collected during three years (1962, 1963 and 1964), at two stations, in 5, 20, 40 and 60 m water depths, respectively. Dictyocha speculum Ehr. was not often seen, whereas D. fibula Ehr. was present all year round. The main forms are D. fibula typica and D. f. var. messanensis (Haeckel) Lemm. The annual cycle of D. fibula, a very constant one, consists of a period of main development during winter and spring, followed by a period of scarcity during summer and autumn. This cycle is very similar to that described by Nival (1965) in Villefranche sur mer. It seems that in Marseilles, as in Villefranche, the development of D. fibula is limited by temperatures over 15 °C. In summer, D. fibula sinks to deeper and colder waters.     

Remarques sur la systématique des Phoronidea X. Notes sur l'écologie,la morphologie et la taxonomie de Phoronis ijimaï et de P. vancouverensis

The ecology, morphology and taxonomy of Phoronis ijimaï Oka, 1897 and P. vancouverensis Pixell, 1912 have been studied in some detail and are compared with those of P. hippocrepia. P. vancouverensis is considered as a synonym of P. ijimaï (which would be demanded by the law of priority). P. ijimaï must be considered as a distinct species and not incorporated into P. hippocrepia.     

Marine fungi deteriorating chitin of hydrozoa and keratin-like annelid tubes

Higher marine fungi were found for the first time as degraders of chitinous exoskeletons of hydrozoa and of keratinous (?) tubes of annelids. Collections were made in several locations of the Atlantic and Pacific Oceans. Fruiting bodies and hyphae of the ascomycete Abyssomyces hydrozoicus Kohlm. occurred on hydrozoa at a depth of 631 to 641 m near the South Orkney Islands. Sterile mycelia, some of them resembling Dictyonema zoophytarum Reinsch, were collected on hydrozoa on the North Carolina coast, and offshore at a depth of 46 to 73 m. Tubes of the polychaete Chaetopterus variopedatus (Renier) washed ashore in California contained ascocarps and mycelia of Lulworthia sp. Hyphal growth on and in the animal tubes is described and illustrated.     

Eine isolierte population von Pseudeuphausia latifrons (Crustacea: Euphausiacea) im Persischen Golf

During the expedition of RV “Meteor” in 1964/1965 a population of Pseudeuphausia latifrons (G. O. Sars, 1883) was found in the Persian Gulf; this population is isolated and morphologically different from a population of the same species in the Arabian Sea. The adults of the Persian Gulf population are between 7 and 16 mm long which means that they are considerably larger than those found elsewhere. Morphological differences of the copulatory appendages of the male specimens from the Persian Gulf can only partly be regarded as allometric, which may be due to the abnormal length of these specimens. It is possible that isolation and the particular ecological conditions in the Persian Gulf have led to genetic changes in this population so that it can be regarded as a distinct geographical variation. Comparative analysis has shown that Pseudeuphausia colosii Torelli, 1934, described from the Red Sea, is synonymous with Pseudeuphausia latifrons (G. O. Sars, 1883).     

Sur l'association de Phoronis australis (Phoronida) avec Cerianthus maua (Ceriantharia) dans les zones récifales de Madagascar

The occurrence of Phoronis australis Haswell in the tubewalls of Cerianthus maua Carlgren at Madagascar allows us to describe the taxonomic characteristics of both species and to deal with ecological aspects of the bottoms colonized. The tube wall of C. maua may be divided into 5 distinct layers. P. australis builds his own tube (whose position in the cerianthid-tube is studied): the ampulla always occurs in the fourth layer, and the lophophore projects externally. The Phoronis australis-Cerianthus maua association can be defined as an inquilinism on the basis of three relations: substrate, feeding, protection (C. maua probably obtains no advantage from this association).     

Fitting a parabola to growth data of fishes and some applications to fisheries

Denoting a fish length or weight at age t by X _t , a reference age by t _m , and the corresponding fish length or weight by X _m , the relation between age and length or weight may be described by a parabola as follows: $$\left| {X_t } \right. - X_m \left| = \right.a + b(\left| {t - t_m } \right.\left| ) \right. + c(\left| t \right. - t_m \left| ) \right.^2$$ or $$X_t = A + b(\left| {t - t_m } \right.\left| ) \right. + c(\left| t \right. - t_m \left| ) \right.^2$$ where a, b and c are constants. Each of the above Eqs. describes one curve at ages older than t _m and another one at younger ages, which is made possible by means of the transformation of t to (|t-t _m |). In 2 cases out of 10, the parabola takes the form of a cubic equation. Evidence is given that, as the growth data become fewer, the better fit of the parabola or cubic equation will probably be less in comparison to the von Bertalanffy equation (1938, 1949) as developed by Beverton and Holt (1957) and the power-growth equation (Rafail, 1971), and vice versa. This growth equation is used to derive models for estimating the optimum age and yield for fish populations.     

Der Lebenszyklus vonAcrosiphonia grandis (Acrosiphoniales,Chlorophyta)

Acrosiphonia granlis Kjellm, is well characterized by its long rows of intercalary fertile cells. Material obtained from Iceland proved to be very interesting by reason of its peculiar life history. The zygote develops into a codiolum-like stage, which grows directly into anAcrosiphonia thallus at an age of some 20 days without formation of swarmers. The same features have recently been demonstrated byJónsson (1967) in an Icelandic species, identified by him asAcrosiphonia sonderi. From his specimensJónsson described facultative caryogamy, ascertained by him formerly in otherAcrosiphonia species: its absence induces the above-mentioned development, giving rise to a generation of mictohaplonticAcrosiphonia. In contrast, true zygotes of “Acrosiphonia sonderi” develop into fertile codiolum cells, reproducing themselves by biflagellate swarmers. InA. grandis, facultative caryogamy has not been observed and nuclear fusion occurs in all zygotes. Codiolum stages never produced swarmers. The life history ofA. grandis represents an intermediate type between the heteromorphic cycle of species such asA. spinescens (including a true codiolumsporophyte), and the isomorphic life history ofA. arcta, where the zygote develops directly into the filamentous plant.     

Loxomespilon perezi — ein entoproctenfund im mittelatlantik. Überlegungen zur benthosbesiedlung der Großen Meteorbank

In dredge-hauls on the Great Meteor Seamont (Canary Basin), the loxosomatid entoproct Loxomespilon perezi Robin et Prénant has been found growing under the elytra of the aphroditid polychaete Sigalion squamatum; L. perezi was attached to the dorsal surface of the polychaete. This is the third find of Loxomespilon, a genus first described from the coastal waters of Bretagne (France) and later from the Plymouth region (England); in all 3 places Loxomespilon was associated only with sigalionid polychaetes as hosts. The question of specificity in the host relationship of Loxosomatidae in general, and this genus in particular, is discussed. Because the Meteor Seamount has little primary production and a very poor fauna, which spreads sporadically over its plateau, there is believed to be little chance for the associated species of Sigalion and Loxomespilon to exist permanently on that bank. It is assumed that there must be a faunal reservoir in the surrounding deep sea. The possible pathways of benthos settlement on the Great Meteor Seamount are discussed.     

Reproduction asexuée chez Phoronis psammophila

Reproduction by transverse fission in Phoronis psammophila Cori occurs in the muscular region of the trunk and divides the animal in two. The posterior fragment regenerates an anterior end, as described by Emig (1972), but completion of the first stages requires longer. The regenerating oesophagus fuses with the epidermis, and the mouth originates by intraepithelial invagination followed by epidermal invagination. The anterior fragment regenerates an ampulla (posterior end) principally by morphallaxis. Organogenesis concerns only the stomach and stomachal blood-sinus. The regenerating stomach (endodermal) and oesophagus (ectodermal) are obtained by differentiation of the prestomacal cells. Asexual reproduction in P. psammophila is a means of rapid numerical increase in the population.     

Einsatz der Hasse-Diagrammtechnik zur vergleichenden Datenanalyse von Biomarkerantworten und ökotoxikologischen Tests

Ecotoxicological investigations focus on biological systems and their response to chemically induced stress. Experimental techniques are much more developed than deterministic dynamic modelling. In this methodological contribution a technique is presented, based on lattice theory. This technique, also calledHasse diagram technique, allows data analysis with respect to comparative evaluation. Hasse diagrams are used

? to suggest a possible measure of microbial diversity,

? to analyze dependencies between phospholipid fatty acids and simple geochemical parameters on an ordinal scale and

? to visualise complex results of interactions of humic substances with xenobiotics.

     

Fortpflanzungsbiologie,Entwicklungszyklen und vergleichende Frühentwicklung acoeler Turbellarien

Copulation and egg-laying of 3 species of marine Convolutidae are compared and analysed in relation to internal structure, settlement behaviour, and habitat. Convoluta convoluta (Abildgaard) inhabits the sea-weed belt, Archaphanostoma agile (Jensen) the uppermost layer of sediments rich in detritus, and Pseudaphanostoma psammophilum Dörjes the mesopsammal. The structure of sexual organs and the mechanisms of sperm transfer are discussed in regard to phylogenetic lines of development. The complete set of hermaphroditic sexual organs and the mutual copulation in c. convoluta are considered to be primitive. The reduction of the female organs, as well as the pronounced differentiation of the male copulatory organs, and the hypodermal sperm injection in A. agile and P. psammophilum are more advanced. In regard to structure and function of its sexual organs, P. psammophilum is extremely well adapted to its habitat. C. convoluta probably deposits the eggs through its pharynx. In A. agile and P. psammophilum egg-laying is associated with a rupture of the body wall. In general, C. convoluta lays 20 to 30 eggs. A. agile 1 to 7 eggs, in a single mass, a few days after copulation, P. psammophilum produces up to 15 single eggs over a period of up to 20 days after the preceding copulation. Among other features, this fact characterizes P. psammophilum as a typical inhabitant of the mesopsammal. While A. agile and P. psammophilum are capable of producing eggs continously, C. convoluta requires more than 14 days before it is again able to release another egg-mass. If kept isolated, A. agile lays eggs extremely rarely; individuals hatched from such eggs do not survive. Three species of acoelous turbellarians could be cultivated successfully at 16° to 18°C; A. agile and P. psam-mophilum were fed with datoms of the genus Nitzschia; Pseudohaplogonaria vacua Dörjes (Haploposthiidae) fed only on A. agile. In order to prevent bacterial infection, 0.25 g/l p-Aminobenzolsulfonacetamide were added to the sea water used as cultivation medium. Embryogenesis of A. agile and P. psammophilum lasts 2 to 5 days, that of P. vacua, 9 to 15 days. On an average, freshly hatched A. agile require 23 days for attaining sexual maturity, P. psammophilum 33 days, and P. vacua 70 days. Normally, A. agile lays 11 to 12 eggs, P. psammophilum 7 to 8 eggs, within 10 days, while P. vacua lays only sporadically (one specimen produces only about 10 eggs within 200 days). These differences in rates of reproduction correspond to respective differences in rates of loss through predation and population densities in the natural environment. A. agile is especially well suited for laboratory experiments; it can be cultured easily, and is characterized by constant production of eggs, and considerable longevity; even after 19 months, cultured A. agile exhibited undiminished vitality. In A. agile, duration of embryogenesis and postlarval development, as well as egg production, were examined at different constant temperatures. The upper lethal temperature of A. agile is 25° to 26°C; egg production is markedly lower at 22°C than at 16° to 18°C; at 16° to 18°C and at 5° to 6°C, rate of propagation is nearly the same, provided that A. agile has been adapted to a constant temperature of 5° to 6°C for a sufficient period of time. Egg production is considerably diminished at 3° to 4°C; it ceases at-1° to +1°C. A. agile is extremely resistant to starvation. Specimens kept without food first resorb their oocytes, then their sexual organs, and finally the greater part of their somatic cells. Of 15 A. agile, 12 survived after 50 days of starvation; the survivors became reduced to the size of newly-hatched young; they attained their normal size again after a feeding period of 30 days. In 13 species of oviparous acoelous turbellarians, development of living embryos was observed until gastrulation (16-cell stage). These observations, on a wide variety of forms, demonstrated that the “Spiral-Duett-Furchung” represents the typical cleavage modus in the Acoela. Examples are provided of the embryogenesis of A. agile and Archocelis macrorhabditis Dörjes. In the two very small species Diopithoporus brachypharyngeus Dörjes and Acoela gen. spec. 2 (200 to 300 μm) which live in sublittoral fine sand, embryonic development occurs inside the parents. In these species, cleavage could be followed clearly only to the 4-cell stage. Particular attention was paid to embryos which developed atypically; the pertinent results allow a re-interpretation of the reports by Bogomolov (1960) and Steinböck (1966) on the embryogenesis of acoelous turbellarians.     

Etude des bactéries associées aux Algues marines en culture

Some bacteria strains have been isolated from marine algae cultures and assigned tentative genera and species. Observations and tests were conducted using Bergey's manual and specific papers on marine bacteria as taxonomic keys. The genera Pseudomonas, Flavobacterium and Achromobacter appear to be the most important, as far as the number of species is concerned.     

Evaluation de la matière organique vivante dans les eaux marines par la mesure de l'adénosine triphosphate

Quantitative determination of living organic matter (micro-organisms) in the ocean were made using the adenosine triphosphate (ATP) assay. Strehler and Totter's (1952) method was used. A simple apparatus recorded the photons emitted from the very beginning of the photochemical reaction; the assay is specific for ATP but enzymes present in Photynus pyralis suspension may create errors. The sea-water ATP values in Marseilles Bay range between 2.10^-2 and 80.10^-2 mg per m³. An offshore profile of the Mediterranean Sea, near Toulon, gives values around 10^-3 mg/m³. Protein assays have been made on the same samples. The differences existing between certain values in the series are attributed to inert particles.     

Thalassoma amblycephalus ein neuer Anemonenfisch-Typ

Observations in the Indian Ocean near Shimoni (Kenya) have added the labride Thalassoma amblycephalus (Bleeker) to the list of fishes which regularly visit sea-anemones. If disturbed, the fish seeks protection near the column or under the oral disk of anemones. It normally visits the anemones spontaneously, inspects the tentacles and picks up small food particles caught by the anemones; this behavior characterizes T. amblycephalus as a food parasite. New observations, and the fact that T. amblycephalus is a labride and not a pomacentride like the species of Amphiprion, Dascyllus and Premnas-other fishes known to establish associations with anemones-throw new light on the ecological importance of anemone-fish associations.     

Untersuchungen über die temperaturabhängigkeit des sauerstoffverbrauchs von Crepidula fornicata (Mollusca: Prosobranchia)

The oxygen consumption of the sessile gastropod Crepidula fornicata was measured during autumn 1962 as a function of soft body wet weight (0.04 to 5.2 g) and temperature (2° to 30° C). From the data obtained, the parameters of the allometric formula were derived for describing the relationship between respiration and body size. The parameters were then used for calculating the oxygen consumption of 3 different weight groups (0.1 g, 1.0 g, 10.0 g) at different temperatures. The resulting plot reveals different curves, demonstrating that the influence of temperature on the metabolism of C. fornicata is a function of body size. The ourves relating oxygen consumption to temperature may well be described by a modified Arrhenius-function proposed some years ago (Krüger, 1962). Biological temperature curves may be described by growth functions. Therefore, it is possible to apply the simple Walfordplot for identifying the “normal curves” of Krogh (1914).     

Effet de l'irradiation gamma (cobalt 60) sur les cultures d'une chlorophycée,Dunaliella bioculata

The influence of gamma radiation on the rate of cell division and the amount of chlorophyll a per cell was studied for Dunaliella bioculata Butcher, 1959 cultures. A decrease in the cell-division rate and an increase of chlorophyll a per cell were observed.