The Rate of Carbon Dioxide Emission into the Atmosphere from a Southern Karelian Mesooligotrophic Bog

Carbon dioxide exchange in the intact and reclaimed sites of a woodless mesooligotrophic dwarf shrub–cotton grass–sphagnum bog was studied in field experiments. The average values of gross respiration in the ecosystem over the warm period (including respiration of plant cover, CO₂emission from peat, and CO₂flow from the litter) were 3.17 and 6.11 g CO₂/m²per day in the natural and drained sites, respectively.     

Variation of leaf gland volatile oil within a population of sweet gale (Myrica gale) (Myricaceae)

Summary The leaf gland volatile oils of ten sweet gale plants from a Scottish population were extracted in early summer. The results differed notably from reports of other populations in respect of the sesquiterpenes, IDDLE" BORDER="0">-elemenone and germacrone, which were major components of the volatile oil. Three dihydrochalcones were also detected in the volatile oil. Variation within the population existed, particularly with respect to the relative importance of germacrone. Five plants were resampled in late summer and exhibited a marked reduction in IDDLE" BORDER="0">-elemenone, a lesser reduction in germacrone and changes in the proportions of some monoterpenes.     

Modes of water manipulation by the lobate ctenophore Leucothea sp.

Examination of the lobate ctenophore Leucothea sp. has revealed new patterns of swimming and water manipulation in addition to the typical ctenophore mode of slow swimming with ctene plate (comb) ciliary propulsion. We distinguish between slow ctene propulsion and rapid ctene propulsion; the latter is accomplished by an increased ciliary beat that produces a coupled vortex wake, resulting in jet propulsion. The large oral lobes both capture prey and provide undulatory muscular propulsive power. The auricles exhibit distinct phasic synchrony and aphasic or sculling motions that generate small vortices in the water which facilitate prey capture. Distinctive papillae covering the exterior of Leucothea sp. may be chemo- or mechano-sensory structures. The integration of all of these structures results in an organism that is more complex behaviorally than might be expected on the basis of its superficially simple and delicate body plan. Field work involved blue-water diving in the waters of the California Bight during June and July, 1985.     

Protracted estuarine phase in the life cycle of the marine pufferfish Torquigener pleurogramma

The present study was undertaken to elucidate the way in which the Swan Estuary in south-western Australia is used by the common blowfish Torquigener pleurogramma, a representative of the abundant and widely distributed family Tetraodontidae. T. pleurogramm were collected by beach seine and otter trawl from the Swan Estuary between February 1977 and December 1980 and between May 1984 and February 1986. While T. pleurogramma feeds on a wide variety of organisms in the estuary, the main components of its diet are polychaetes and amphipods for fish <130 mm and bivalve molluscs for larger fish. Numbers of blowfish were inversely correlated with water depth, with densities on the banks (water depth <1.5 m) sometimes reaching 5 fish m^-2, and tended to be greater at night than during the day. The density of T. pleurogramma in the shallows was positively correlated with salinity and inversely correlated with distance from the estuary mouth. Numbers increased greatly in the latter half of 1980 and 1985 as a result of the recruitment of large numbers of the 0+ age class (i.e., fish in their first year of life). Blowfish were represented by seven age classes in the estuary and attained a maximum size of 230 mm (220 g). By the end of their first and second years of life, fish had reached approximately 90 mm (14 g) and 125 mm (39 g), respectively. Sexual maturity was generally not reached until the end of the second year of life. The presence of higher gonadosomatic indices and more mature gonads in fish collected just outside than within the estuary indicate that T. pleurogramma leaves the estuary before spawning. Comparisons between lengthfrequency data, allied with information on the prevalence and intensity of gill parasites, indicate that assemblages in estuarine and neighbouring inshore waters remain distinct for many months and that growth within the estuary is faster than in inshore marine environments.     

Isolation of DNA and RNA from ascidians

Combined effects of temperature, salinity and nutrition on larval survival and growth of the European oyster Ostrea edulis L. were studied over a period of seven days in the laboratory. Larvae were obtained in August 1985 from oysters reared under field conditions on the Mediterranean coast. Four temperatures (15°, 20°, 25°, 30°C), four salinities (20, 25, 30, 35IDDLE" BORDER="0"> S) and two levels of nutrition (fed or unfed) were used in the experimental design; the fed larvae received a mixed algal diet of Isochrysis galbana and Chaetoceros calcitrans forma pumilum at a concentration of 100 cells per microlitre. Larvae survived over a wide range of temperature and salinity; statistical analysis indicated that nutrition had the greatest effect on the development of O. edulis larvae, explaining 85 to 88% of the variance in growth. Compared with temperature, the effect of salinity was very slight, usually statistically insignificant. The combined effects of temperature and nutrition produced the only significant interaction. Growth of starved larvae seems to be independent of both temperature and salinity within the range of levels tested.     

Siliceous sponge spicules in coral reef sediments

Experimental etching with hydrofluoric acid indicated that silica deposition occurs in a recognizable pattern in common sponge microscleres. The postdepositional alteration of these spicules has previously been generally unrecognized or misinterpreted in the literature. Early stages of postdepositional etching of sponge spicules were observed in the acid insoluble fraction of sediments from the West Atlantic barrier reef near Carrie Bow Cay, Belize. Preliminary data on silica distribution in the Belize barrier reef show that concentrations in fine sediment (<0.25 mm) increase landward of the main reef tract. Sponge spicules are the main component of particulate silica in sediments of the reef and fore-reef where sponge populations abound, whereas grains prevail in the back-reef lagoon deposits. Recycling of locally dissolved silica appears to be important for the growth of many off-shore reef sponges.     

Nutrients and biomass distribution in the Gulf of Aqaba (Elat), Red Sea

The distribution of phosphate, nitrate and silicate values obtained from 300 samples and of biomass determined by displacement volume in about 1,900 vertical plankton hauls (65, 200 and 330 IDDLE" BORDER="0">m) collected from 8 oceanographic station during 1974–1975 in the Gulf of Aqaba (Elat) are summarized and illustrated by crosssections. Generally, the Gulf is poor in nutrients and the data indicate that it is filled with upper (150 m) Red Sea waters, flowing in over the sill of Tiran. Nutrient content of the upper and deep waters immediately outside the sill are well within the known range of those in the northern Red Sea. Biomass values are relatively low in the Gulf are generally similar to those reported from the northern Red Sea. Both nutrients and biomass values display seasonal and bathymetric variations in the Gulf and outside the sill.     

Age-and sex-dependent patterns of aggregation in the tropical gastropod Strombus luhuanus

The spatial dispersion of the tropical coral sand-dwelling mesogastropod Strombus luhuanus Linné, 1758 was studied at several sites in two localities (Australian Great Barrier Reef and southern Papua New Guinea), from September 1980 to February 1983. S. luhuanus usually occurred in local aggregations, many of which were relatively dense with discrete boundaries: Four types of aggregation are described: mixed age-class, juvenile, mating, and clusters. The former two are termed colonies, because they persisted over time and exhibited some coordinated movements. Mixed age-class colonies contain individuals of all ages, but within them the different ageclasses are frequently spatially segregated from each other. This was sometimes due to the younger age-classes' preference for shallower areas, but also occurred in areas of constant depth. Juvenile colonies are relatively smaller in area but higher in density, and are dominated by a single size-class. Mating aggregations are concentrations of copulating individuals, in which competition between males for access to females occurs. Clusters are concentrations of inactive individuals (juvenile and adult) piled together in close contact. All types of aggregation were concentrated in only a part of what appeared to be the suitable habitat. Most aggregations' boundaries shifted over time within the habitat. We conclude that intraspecific attraction must be an important factor which maintains the spatial structure of all aggregations, although habitat specificity sets the larger area in which they move. Processes which may underlie this pattern, and some of its implications, are discussed.     

Morphological correlates of intraspecific grafting reactions in the marine demosponge Callyspongia diffusa

There are profound differences in the ways that the sponge Callyspongia diffusa reacts to self versus non-self tissue contact. Syngeneic or isogeneic contacts result in rapid tissue fusion and persistent maintenance of normal sponge structure. However, allogeneic contacts result in immune-type rejection reactions leading to tissue death at the interface. Using grafted sponge tissues, both types of response were subject to fine-structural analysis by scanning electron microscopy. Isografts showed no overt cellular reactions other than compatible fusion, whereas sponge tissues at allograft interfaces showed incompatibility reactions. The major steps in the histopathologic sequence of events in allograft reactions may be summarized as follows: (1) immediate allorecognition occurs accompanied by microscopic cellular rearrangements; (2) macroscopic tissue bridges form across the graft interface; (3) massive cellular infiltration towards graft sites, with cells often passing into a graft partner through the tissue bridges; (4) cellular hyperplasia and then cell death occurs at the interface; and (5) sloughing of dead tissue leaves areas of vacant skeleton between the two grafted individuals. Allograft rejection reactions in sponges have many of the hallmarks of histoincompatibility reactions in higher animals. Although there could be different alloimmune mechanisms operating in different animals, the salient events of allorecognition and antagonistic rejection appear strikingly similar among diverse multicellular animals.