Reproductive cycle of Golfingia margaritacea,a bipolar sipunculan,in subantarctic water

The reproductive cycle of the bipolar sipunculan Golfingia margaritacea collected from Ushuaia, Argentina (54°49 S; 68°13W) in 1986 and 1987 is reported. The population sampled showed a sex ratio of 1:1. Males, however, frequently outnumbered females. Measurements of coelomic oocytes delineated an annual reproductive cycle. Small oocytes were present in the coelom all year: a subpopulation began to increase size about the middle of spring and reached its maximum size in late summer. Spawns may occur from the end February to April. May is characterized by resorption of large oocytes. Monthy monitoring of the gonads revealed mitotic activity and a continuous release of gametocytes to the coelom. Parasites were detected in the gonads. Large coelomic oocytes were also present in the coelom during the same season in the Northern and Southern Hemispheres, but egg sizes were significantly larger in boreal populations.     

Reproductive cycle of two populations of Ophionereis schayeri (Ophiuroidea) in New South Wales

Reproduction of two populations of Ophionereis schayeri (Müller and Troschel) in New South Wales was investigated from November 1991 through January 1993. The reproductive cycle was documented by histological examination of the gonads and by image analysis to determine the oocyte size-frequency distributions. Both populations of O. schayeri were mature in December and January and had a major summer spawning period between January and February. Thereafter, the condition of the gonads exhibited interindividual variability, with asynchronous low-intensity gamete release through August. O. schayeri has the potential to spawn for up to 8 mo of the year. This breeding pattern with synchronous spawning in summer and asynchronous gamete release through winter was similar in both populations. During autumn and winter, the gonads contained developing gametes and advanced gametes ready for spawning. The eggs spawned by O. schayeri during these seasons started their growth during the previous spring vitellogenic period, and continued to grow through summer. Upon reaching full size, they were stored for spawning outside the main breeding period. Spring is marked by increased spermatogenic and vitellogenic activity followed by maturation and spawning. Throughout their development, the oocytes of O. schayeri are surrounded by a follicle consisting of periodic acid-Schiff-positive (PAS+) haemal fluid and PAS+ yolk by the oocytes. In the testes, the haemal sinus projects into the centre of the spermatocyte columns, thus appearing to play a nutritive role in support of both oogenesis and spermatogenesis. Late vitellogenic oocytes of O. schayeri are firmly anchored to the germinal epithelium by an attachment complex consisting of specialised attachment cells and basophilic strands that radiate between the oolemma and the nucleus. Spawning is associated with rupture of the follicles, which remain as prominent, empty U-shaped profiles in the ovaries. O. schayeri produces copious numbers of 200 m-diam oocytes, suggesting that this species is a broadcast spawner and that it has a modified ophiopluteus or vitellaria larva.     

Ultrastructure of oogenesis in the holopelagic polychaetes Rhynchonerella angelini and Alciopa reynaudii (Polychaeta: Alciopidae)

Ultrastructural features of oogenesis were examined in the pelagic polychaetes Rhynchonerella angelini and Alciopa reynaudii which were collected from Bahamian waters by a manned submersible during 1979 and 1980. No definitive ovary was detected in either species. Oogonia are released into the coelom as packets of cells, where they undergo mitotic division while surrounded by an envelope of sheath cells. Cytokinesis is incomplete, resulting in intercellular bridges between oogonia. Oocytes undergo early stages of meiosis characterized by the presence of synapsed chromosomes, followed by a period of rapid cytoplasmic and nuclear growth. Oocytes are released from the packets in the early vitellogenic phase into the coelom, where they undergo yolk synthesis as solitary coelomic cells. Vitellogenesis includes both autosynthetic and heterosynthetic processes. Autosynthesis involves the fusion of secretory vesicles formed by the combined activity of the rough endoplasmic reticulum and Golgi complex, with convoluted electron-dense tubular bodies of unknown origin. Heterosynthesis involves the intense uptake of exogenous precursors through endocytosis and their fusion into nascent yolk bodies which, in turn, are presumed to fuse with autosynthetically-derived yolk bodies. No nutrient stores were detected in somatic tissues. Early and middle stages of vitellogenic oocytes were absent from the coelom. This absence combined with the high level of endocytotic activity suggests that vitellogenesis occurs rapidly. These features, in combination with the presence of an exceptionally thin body wall and gut, might serve as related adaptations for predator avoidance by the maintenance of relatively low tissue-density. Alciopid, phyllodocid, and nereid polychaetes share some common reproductive features including the presence of dispersed ovaries, clusters of syncytial germ cells which undergo meiosis while enveloped by somatic cells and the release of oocytes from the clusters prior to vitellogenesis.     

Ist der polychaet Ophryotrocha labronica ein proterandrischer hermaphrodit?

The larvae of an egg-mass of Ophryotrocha labronica differentiate into 60 to 70% males and 15 to 40% females. In the coelom of males, freely floating spermatozoa are visible at a length of 10.5 segments. Oocytes of 5 to 7 m in diameter are released into the coelom of females at 10.7 segments. Males develop the k-jaw (k=complicated) much earlier (at 12.2 segments) than females (at 16.5 segments). As described for O. notoglandulata, O. labronica bears star-shaped glands on the dorsal side of the youngest segments. Males always have more glands (4.4) than females (2.7). These glands and the different appearance of the k-jaw may be considered as sexual characters. At 13.5 segments, 60 to 70% of the males start to proliferate oocytes, thus displaying protandry. The remaining males do not undergo sex reversal and are thus categorised as stable males. The developing oocytes in the so-called secondary females are not shed but ultimately resorbed. Resorption also occurs in isolated females, which display female differentiation from the beginning. The number of glands in secondary females decreases during sex reversal to values as low as those observed in stable females. Rearing experiments revealed the secondary females to be completely infertile. Inhibition of oocyte release in secondary females is permanent, and such release cannot be induced, even by the presence of males. Self-fertilization was not observed.

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Dankenswerterweise unterstützte die DFG die Untersuchung durch eine Reisebeihilfe.     

The body wall of cheilostome Bryozoa,V. Frontal budding in Schizoporella unicornis floridana

Schizoporella unicornis floridana Osburn from Maryland and New Jersey, USA, produces two types of autozoids: (1) primogenial zoids, arranged in the brick-like quincunx pattern usual among cheilostomes; (2) adventitious, or frontally-budded zoids. Adventitious zoids are produced by expansion of the epitheca of primogenial or other adventitious zoids. The old aperture is sealed over and the hypostega becomes the body cavity of a new zoid. Vertical walls of adventitious zoids all contain an intercalary cuticle; basal walls are the frontal walls of zoids beneath. This sometimes results in trepostome-like zoid columns arising from the substrate; zoid columns may bifurcate in a way similar to zoid row-bifurcation in primogenial zoids. Adventitious zoids communicate with zoids at the same depth in the colony through annular septulae; they communicate with younger and older zoids through areolae. Adventitious zoids may sometimes give rise to primogenial subcolonies, which overgrow the colony surface. Frontal budding allows the development of massive nodules, which are of geological importance. These findings indicate that the hypostegal coelom is at least potentially a bud, and that genetic information necessary for producing an autozoid may be transferred from one building site to another. This idea has important implications in studying evolution of positions of zoids in a colony.This research, conducted in the Department of Invertebrate Paleontology at the National Museum of Natural History and at The American University, was supported in part by a Smithsonian Institution Visiting Postdoctoral Research Fellowship and by an American University Summer Research Grant, funded by a National Science Foundation Institutional Grant.     

Reproduction in Amphiura filiformis (Echinodermata: Ophiuroidea): Seasonality in gonad development

The burrowing ophiuroid Amphiura filiformis (O. F. Müller) (Echinodermata: Ophiuroidea) colonises an extensive area and is a numerically dominant member of the macrofauna in Galway Bay on the west coast of Ireland. There, it has a discrete, relatively short annual breeding period, from June to September, with peak activity in the month of August. The breeding period approximates in timing those of other European populations. The oocytes of a particular year are laid down in the autumn of the previous year; they begin to develop in spring, with the period of fastest growth in May/June. Gonad growth corresponds quite closely to the annual rise in water temperature, with spawning taking place during the warmest months of the year. The species is polytelic, and it is suggested that the long-lived Galway Bay individuals may breed every year for several years. The relationship between spawning and population dynamics is discussed in the light of current, available literature concerning A. filiformis from other parts of Europe. The role of so-called ultimate factors in the process of ophiuroid maturation and spawning is discussed.     

Aqua regia extractable trace elements in surface soils of venezuela

Surface soils (0–15 cm) were sampled at 10–20 km intervals along two transects in Venezuela. One (1162 km, 70 samples) ran west to east parallel with the Caribbean coastline, the other (920 km, 92 samples) ran south to north from the frontier with Brazil to the Caribbean shore. Sampling took place in both a wet and a dry season. Trace metals were extracted from dried, sieved (<2 mm) soil with boiling aqua regia followed by analysis by ICP or flame AAS. Metal values did not differ significantly between the two seasons and dates were averaged. Geometric mean values for the west–east transect were: Cr=41.5, Cu 17.9, Cs 3.6, Li=13.9, Mn=294, Ni=21.3, Pb=17.4, Sr=39.4, V=60.4 and Zn = 83.7g g^–1, respectively. Similarly, for the south–north transect Cr=21.3, Cu=4.3, Cs=1.1, Li=2.0, Mn=55.7, Ni=4.4, Pb=6.1, Sr=13.3, V=28.2 and Zn=16.7g g^–1, respectively. A classification of samples by lithology showed surface soil composition to be related to rock composition. Metal values were low in the soils in the south of the country, in the Guyana highlands (Gran Sabana). Low Zn contents were prevalent. Lead contents were affected by roadside fallout from vehicles using leaded petrol except that high Pb contents of soils in the Gran Sabana were of more complex origin.     

Seasonal migrations of plaice (Pleuronectes platessa) through the Dover Strait

Analysis of paired-haul mid-water trawling experiments conducted in the five months November to March during the years 1985 and 1988 revealed the seasonal pattern of migration of plaice (Pleuronectes platessa L.) moving through the Dover Strait between the Southern Bight of the North Sea and the English Channel. Mid-water catches of maturing fish were highest on south-going tidesprior to peak spawning (late January), while catches of spent fish, were highest on north-going tidesafter peak spawning. Detailed analysis of the catch data provided evidence that males complete their pre-spawning migration earlier, and their post-spawning migration later, than female fish and consequently spend more time on the spawning ground. Catches of immature female fish indicated a migration south following that of the mature fish. This dummy run may be a method by which immature plaice use the presence of high densities of mature and spawning fish to learn the location of the spawning ground. The analysis also indicated that differences in catch rates between day and night are unlikely to be the result of gear avoidance by day. The results confirm that selective tidal-stream transport is a key migratory mechanism for plaice in areas of fast tidal streams on the European continental shelf.     

Annual reproductive cycle of the captive female Japanese sardineSardinops melanostictus: Relationship to ovarian development and serum levels of gonadal steroid hormones

Gonad and blood samples were taken from the captive female Japanese sardineSardinops melanostictus between 1988 and 1989, and changes in serum levels of gonadal steroids were correlated with the annual gonadal cycle. Under captive conditions, female fish did not mature and spawn spontaneously, although oocytes developed up to the end of vitellogenic growth. Based on evidence from ovarian histology, the annual gonadal cycle of the Japanese sardine was divisible into four periods, i.e., immature (June to October), vitellogenesis (November to December), spawning (January to March), and post-spawning (April to May). The pattern of seasonal change in the gonadosomatic index (GSI) showed an inverse correlation to change in water temperature and reflected the degree of ovarian maturity. The serum estradiol-17 level increased from its lowest concentration (0.12 ng ml^–1) in September to a peak (1.14 ng ml^–1) in March. Serum 17,20-dihydroxy-4-pregnen-3-one (17,20-P) was detectable at low levels (<0.3 ng ml^–1) between October and February, but was below the assay detection limit (0.06 ng ml^–1) at all other times. Testosterone was not detectable (<0.06 ng ml^–1) in the serum of any fish throughout the year. The effects of several steroids on the maturation of follicle-enclosed oocytes of sardine were examined in vitro, and 17,20-P was found to be the most potent inducer of maturation. This suggests that post-vitellogenic oocytes of the Japanese sardine in captivity have an ability to respond to an appropriate hormonal effector and subsequently to resume meiotic maturation.     

Reproductive biology of commercially exploited deep-water royal red prawns (Haliporoides sibogae,Solenoceridae) in south-east Australia

Deep-water royal red prawns (Haliporoides sibogae de Man, 1907; Solenoceridae: Penaeidea) were sampled from commercial catches off south-east Australia between November 1988 and May 1990. Four stages of sexual development were distinguished macroscopically for each sex. For the females, histology and analysis of oocyte size were used to validate the macroscopic staging of ovaries into undeveloped, developing, early ripe and ripe. Females were larger than males, reaching a maximum size of 46 mm carapace length (CL) compared to 32 mm CL for males. Average size at sexual maturity was 30.8 mm CL for females and 25.8 mm CL for males. Females apparently breed several times in their life, whereas males probably breed only once. Individual fecundity (ranging from about 58 000 to 140 000 oocytes) was relatively low compared with other penaeids, but oocytes were larger (mean diameter=0.41 mm). Two short breeding seasons occurred per year (February to April and July to August). There was a clear size-related latitudinal distribution of the prawns, with largr prawns (spawners) being more abundant in the northern region of the fishing area, and juveniles (CL20 mm) being more abundant in the south. Most of the spawning stock probably lies outside the main fishing ground, while the fishery targets mainly prawns below the size at maturity.     

Gonadal cycle in an<Emphasis Type="Italic"> Adelomelon brasiliana</Emphasis> (Neogastropoda: Volutidae) population of Buenos Aires province,Argentina

The reproductive season of the Adelomelon brasiliana population of Mar del Plata extends from September to April (austral spring and summer), showing synchronisation with water temperature. Adult gonad state is related to shell-free wet mass. Oocytes reach 200 m in diameter before spawning. In autumn, a resting phase begins, when no new oocytes develop and the non-spawned ones undergo reabsorption. Gonadic development begins during the early winter, when new previtellogenic oocytes can be observed through histology. The long reproductive season would increase the ability of the species to recover from harvesting.Communicated by O. Kinne, Oldendorf/Luhe     

Acclimation of gametes to reduced salinity prior to spawning inLuidia clathrata (Echinodermata: Asteroidea)

AdultLuidia clathrata (Say) were held at salinities lower and higher (25 to 35) than environmental salinity (29) during gametogenesis and after sperm and primary oocytes were produced. The sperm and primary oocytes acclimated to the experimental salinities in both cases. Fertilization and development through gastrulation were not affected at the salinities at which the parents were held, but were affected at altered salinities. This indicates that intracellular osmoregulation can occur both during gametogenesis and after the stage of arrested activity has been reached. This is an important capacity forL. clathrata, which lives in estuaries with variable salinities.     

Dynamics of the TIT FOR TAT strategy during predator inspection in the guppy (Poecilia reticulata)

Summary One well-known solution to the iterated Prisoner's Dilemma is the TIT FOR TAT strategy. This strategy has three characteristics associated with it. TIT FOR TAT is nice (cooperates on the first move of a game), retaliatory (plays defect against an individual that defected on the prior move), and forgiving (cooperates with an individual which has defected in the past but cooperates in the present). Predator inspection behavior in guppies (Poecilia reticulata) was examined in order to determine whether guppies displayed these three characteristics. Results indicate that while it can be quite difficult to translate the abstract concepts of niceness, retaliation, and forgiveness into measurable behaviors, the data support the hypothesis that guppies display the three characteristics associated with the TIT FOR TAT strategy.The selfish herd and dilution effect are discussed as possible alternative explanations for the observed behavior. These hypotheses alone were insufficient to explain the results.     

Reproduction and reproductive variability in the coral Pocillopora verrucosa from the Republic of Maldives

The sexuality, reproductive mode, and timing of reproduction of Pocillopora verrucosa from the Republic of Maldives, Indian Ocean, were assessed using serial histological sections. These showed that P. verrucosa is an annual simultaneous hermaphrodite, with gonads arranged in two opposing arcs of alternating testes and ovaries, six gonads in each arc. No planulae were observed in any dissection or histological analysis carried out, therefore making brooding unlikely. Broadcast spawning is inferred from the disappearance of mature gametes from samples collected between late March and April 1991. Mean oocyte size at spawning was 53.5 m and mean potential fecundity was 7300 ooctyes cm^-2yr^-1. The reproductive pattern of P. verrucosa in the Maldives is compared to that of the same species in different locations, the short breeding season in March to April occurring earlier in the Maldives than in Red Sea populations. The maximum mean oocyte diameter found in Maldivian specimens was much smaller than elsewhere. The year-to-year variation in numbers of oocytes/polyp within single colonies, and the variation between colonies within the population was significant (p<0.01). Therefore, it is possible that fecundity is not a good variable to use when monitoring stress on coral reefs unless larger numbers of estimates can be routinely made. Some colonies contained immature oocytes at spawning that were not released and continued to grow to approximately twice the size of the spawned oocytes that were presumed to be mature. These unspawned oocytes were oosorbing, and were characterised by the presence of zooxanthellae and large numbers of vacuoles in their cytoplasm. This gradual expansion and oosorption of unspawned oocytes has not been documented previously for corals.     

Effect of inhibitors of carbonic anhydrase activity on photosynthesis in the red alga Soliera filiformis (Gigartinales: Rhodophyta)

The effect of light intensity, pH and carbonic anhydrase (CA) inhibitors on photosynthesis of the red marine macroalgae Solieria filiformis (Kützing) Gabrielson, collected from Taliarte (Gran Canaria, Canary Islands) in 1991, has been investigated. Plants taken from the sea (wild phenotype) developed spherical morphology (ball phenotype) after 2 mo culture in aerated tanks. The photosynthetic oxygen evolution in the wild phenotype was saturated at 100 mol photons m^-2s^-1, while the ball phenotype displayed saturation at 200 mol photons m^-2s^-1. The inhibitors of total CA activity (6-ethoxizolamide) and extracellular CA activity (dextran-bound sulfonamide) inhibited photosynthesis at pH 8.2, to 90 and 50% respectively, in both phenotypes. No inhibition of the photosynthetic oxygen evolution was detected at pH 6.5. CA activity was associated with both supernatant and pellet fractions of crude extracts of S. filiformis. The rate of alkalization of the medium by the algae was dependent on light intensity. We suggest that carbon dioxide is the general form of inorganic carbon transported across the plasmamembrane in S. filiformis. HCO₃ transport into the cell takes place simultaneously by an indirect mechanism (dehydration to CO₂ catalyzed by CAext) and by direct uptake. Extracellular (CAext) and intracellular (CAint) CAs are involved in the mechanisms of inorganic carbon assimilation by S. filiformis.     

Behavioral correlations with aberrant patterns in humpback whale songs

Summary Humpback whales emit long, patterned vocalizations referred to as songs. We analyzed songs from 22 recording sessions whick took place from January to April, 1980 on Silver Bank, Dominican Republic. The sequence of patterns (which we call themes) in these songs is remarkably regular. In this sample, there were 427 transitions from one theme to another. Only 20 of these did not follow the expected sequence. We present evidence that some themes are sung out of their usual order far more often than others. We also show that when themes are sung out of sequence, the whale is at the surface, blowing. This finding provides a link between the song structure and humpback behavior. Because aspects of the song structure can be linked to breathing, we hypothesize that a function of the songs is to show how long a whale can hold its breath, and that the duration of a song may be an indication of stamina and physical condition.     

A Preliminary Study on Soil–Gas Radon Geochemistry According to Different Bedrock Geology in Korea

Three study areas of Kwanak campus (Seoul National University), Boeun (Choongbuk) and Gapyung (Kyonggi) were selected and classified according to their bedrock types in order to investigate soil–gas radon concentrations. The mean values of radon concentrations decreased in the order of Gapyung (40BqL^–1) > Kwanak campus (30BqL^–1) > Boeun (22BqL^–1), and decreased in the order of granite gneiss > banded gneiss > granite > black slate–shale > mica schist > shale–limestone > phyllite schist according to bed rock types. Variation in radon emanation with water content in soils and with soil grain size was assessed by the modified Morse (1976) 3min method. Soil–gas radon concentrations increased with increasing water content in the range of less than about 6–16wt.%, but decreased above 6–16wt.%. Radon concentrations also increased with decreasing soil grain size. Radioactivity analysis of radionuclides of ²³⁸U series in some soil samples indicated their possible radioactive disequilibrium between ²²⁶Ra and ²³⁸U due to the differing geochemical behaviour of intermediate radionuclides. Thus, a radioactive isotope geochemical approach should be necessary for soil–gas radon study.     

Sorted samples and quantitative counts in appendicularian catches

Sorting centers are important for processing material collected during extensive oceanic expeditions. Based on information obtained from samples of appendicularians, this paper demonstrates that usual procedures adopted in sorting centers produce samples which contain only a fraction of the organisms present in the original catch (or subsample). In addition, the proportion of individuals sorted varies considerably. In four Indian Ocean Standard Net catches collected in the Arabian Sea, subsamples (called sorted samples in this paper) are compared with careful microscopical counts (quantitative counts) performed by the author. The numbers of appendicularians found in quantitative counts were 2.4 to 19.2 times higher than those in the sorted samples. Sorting efficiency varies in different forms of appendicularians; it is particularly low in Fritillaria sp. Bad preservation and small body size further reduce the portion sorted out. Under certain conditions (e.g. net clogging), numerous small appendicularians are retained which normally would pass easily through the meshes of the plankton net.     

Effects of nitrogen and phosphorus enrichement on in vivo symbiotic zooxanthellae of Pocillopora damicornis

The reef coral Pocillopora damicornis (Linnaeus) was grown for 8 wk in four nutrient treatments: control, consisting of ambient, unfiltered Kaneohe Bay seawater [dissolved inorganic nitrogen (DIN, 1.0 M) and dissolved inorganic phosphate (DIP, 0.3 M)]; nitrogen enrichment (15 M DIN as ammonium); phosphorus enrichment (1.2 M DIP as inorganic phosphate); and 15 M DIN+1.2 M DIP. Analyses of zooxanthellae for C, N, P and chlorophyll a after the 8 wk experiment indicated that DIN enrichment increased the cellular chlorophyll a and excess nitrogen fraction of the algae, but did not affect C cell^-1. DIP enrichment decreased both C and P cell^-1, but the decrease was proportionally less for C cell^-1. the response of cellular P to both DIN and DIP enrichment appeared to be in the same direction and could not be explained as a primary effect of external nutrient enrichment. The observed response of cellular P might be a consequence of in situ CO₂ limitation. DIN enrichment could increase the CO₂ (aq) demand by increasing the net production per unit area. DIP enrichment could slow down calcification, thus decreasing the availability of CO₂ (aq) in the coral tissue.Hawaii Institute of Marine Biology Contribution No. 920     

Elemental composition (C,N,H) in larval and crab-1 stages of Pagurus bernhardus (Decapoda,Paguridae) and Carcinus maenas (Decapoda,Portunidae)

Analyses of individual content of carbon (C), nitrogen (N), and hydrogen (H) were carried out for all larval stages of Pagurus bernhardus and Carcinus maenas, and for newly metamorphosed crabs. Maximum range in total larval development is 12.8 to 165.8 g C, 3.2 to 35.1 g N, and 1.9 to 24.9 g H in P. bernhardus and 3.1 to 43.2 g C, 0.7 to 10.1 g N, and 0.4 to 6.3 g H in C. maenas. From these data energy equivalents were calculated. Maximum range in total larval life is 0.43 to 6.38 J ind. ^-1 in P. bernhardus and 0.1 to 1.49 J ind. ^-1 in C. maenas. There is a 32.4% mean loss of energy in P. bernhardus megalopa development; this seems to describe the normal developmental pattern in this stage. Biomass was determined as fresh and dry weight respectively. Individual dry weight is about 3.6 to 5.6 times higher in P. bernhardus (44 to 340 g) than in C. maenas (12 to 93 g) larvae.Contribution to research project Experimentelle marine Ökosystemanalyse sponsored by Bundesministerium für Forschung und Technologie, Bonn (Grant No. MFU-0328/1)