Morphological variation in the reef coral Montastrea cavernosa in Brazil

Morphological variability is a widespread but poorly understood characteristic of many colonial animals. In this study morphologic variation in Montastrea cavernosa (Linnaeus 1767) from northeastern Brazil is examined. Colonies were collected from three depths: 0–5, 10–15 and 15–20 m at the Abrolhos reefs (Bahia state), and from a single depth (0–5 m) at Tamandaré (Pernambuco state). Fifteen measurements or counts were made on each sample. They include the most important characteristics commonly used to separate species in the family Faviidae. The results of statistical analyses show that almost every character studied varies. Between colonies, localities and depth classes, the most variable features are the spacing of corallites, the diameter of corallite, the height of theca and of outer columella, the thickness of first cycle septa, the length of first cycle costae, and the thickness of fourth cycle costae. Canonical discriminant analyses show that the samples from 0–5 m are the most widely separated from samples collected at the other depth classes. Variability within populations is greater than between, but both are significant. Montastrea cavernosa in Brazil is characterized by high morphological variability and polymorphism within populations and cannot be completely explained by environmental variables.     

Population studies of Laminaria hyperborea from its northern range of distribution in Norway

Eight populations of Laminaria hyperborea from wave-exposed localities in Finnmark (70–71°N) were compared with two populations in Vega (65°N). Standing stock in shallow water (3–5 m) was within the same range in the two areas (6–16 kg fr. wt. m^–2). Both the highest and lowest value of standing stock were registered in Finnmark. Degree of wave-exposure was determined by the numbers of sectors exposed to open sea at each locality, with each sector given a relative wind force value. The most wave-exposed locality in Vega had a slightly higher annual biomass production as a function of plant age compared with the populations from Finnmark within a similar range of wave exposure. Of the two localities in Vega the most wave-exposed one had a higher annual biomass production per plant than the more sheltered one. The most wave-exposed locality examined was situated in Finnmark and exhibited the lowest annual biomass production per plant. Recruits (one-year-old plants) were found at all the localities except at one locality in Finnmark. The plants reached a higher age in Finnmark (13–18 years) than in Vega (8–9 years).     

Habitat and population size of the coelacanth Latimeria chalumnae at Grand Comoro

Synopsis In 1987 and 1989 coelacanths were observed for the first time in their natural habitat with the help of submersibles. Coelacanths were found between 150–253 m depth, their preferential depth seems to be around 200 m; the water temperature ranged between 16.5–22.8° C. During the day coelacanths aggregate in small non-aggressive groups in sheltered lava-caves. Caves might be a limiting factor for distribution. At night they leave the caves for hunting by drifting singly along the steep lava slopes. They migrate between different caves located within a large home range covering more than 8 km coastline. Coelacanths are site-attached, some for a period of at least 2 years. Our own observations and earlier catch records show that only the west coast of Grand Comoro is a suitable coelacanth habitat with more structural complexity and prey fish abundance than other coastlines of the island. From our survey we estimated a total coelacanth population off Grand Comoro to be 150–210 individuals; a saturated population would be 370–510 individuals. This small relict population seems to be stable. International protection of coelacanths against commercial interests is needed     

Classes and mechanisms of calcium waves

The best known calcium waves move at about 5–30 μm/s (at 20°C) and will be called fast waves to distinguish them from slow (contractile) ones which move at 0.1-1 μm/s as well as electrically propagated, ultrafast ones. Fast waves move deep within cells and seem to underlie most calcium signals. Their velocity and hence mechanism has been remarkably conserved among all or almost all eukaryotic cells. In fully active (but not overstimulated) cells of all sorts, their mean speeds lie between about 15–30 μm/s at 20°C. Their amplitudes usually lie between 3–30 μM and their frequencies from one per 10–300 s. They are propagated by a reaction diffusion mechanism governed by the Luther equation in which Ca²⁺ ions are the only diffusing propagators, and calcium induced calcium release, or CICR, the only reaction; although this reaction traverses various channels which are generally modulated by IP₃ or cADPR. However, they may be generally initiated by a second, lumenal mode of CICR which occurs within the ER. Moreover, they are propagated between cells by a variety of mechanisms. Slow intracellular waves, on the other hand, may be mechanically propagated via stretch sensitive calcium channels.     

Growth and age structure of the swan mussel Anodonta cygnea (L.) at different depths in lake Mattsee (Salzburg, Austria)

Unionid clams were collected at 1–2 m, 3–4 m and 6–7 m depth in lake Mattsee, a moderately mesotrophic lake, to investigate the effect of depth on clam growth and age structure. No significant differences in age structure of Anodonta cygnea were found (p=0.65). Three and ten years old clams were present at all depths, but in different percentages. Whereas at 1–2 m 13.3% of the collected clams were <4 years old, this percentage was 4.4% at 6–7 m and 7.1% at 3–4 m. A greater percentage (6.7%) of older mussels (9, 10 years) were collected at 6–7 m than at 1–2 m (2.2%). Growth declined with depth. Total length at a given age of clams at 1–2 m and 3–4 m did not differ (p=0.54), whereas differences were significant between clams at 1–2 m and 6–7 m (p<0.05) as well as between 3–4 m and 6–7 m (p<0.05). The Growth constant k was highest at 1–2 m depth.     

Ultrastructure and functional characteristics of the optic nerve of Rana temporaria L. in the norm and during degeneration

Results of electron microscopy and electrophysiological studies of the frog optic nerve are presented. The nerve contains 96% unmyelinated (about 210,000) and 4% myelinated (8700–14,800) fibers. The peripheral zone of the nerve (20–30 µm) has relatively few myelinated fibers, whereas in other zones these fibers are distributed uniformly (counting area 300–400 µm²). The curve of the distribution of the diameters of myelinated fibers has a number of peaks: a main peak at 1 µm and additional peaks at 0.6 and 1.6 µm (the latter is more prominent). Individual fibers have a diameter of 0.4–3.9 µm. The diameter of the unmyelinated fibers are 0.1–0.4 µm; 64% of these fibers have a diameter of 0.2 µm. Most fibers at a temperature of 18–20° conduct at 0.3–0.4 m/sec and a few (myelinated with a diameter of 1.0–1.6 µm) at 3 and 6 m/sec. After enucleation the myelinated fibers degenerate at first and are phagocytized by neuroglia; the ultrastructure and function of the unmyelinated fibers at 18–20° remain unchanged up to 100 days postoperation.A. N. Severtsov Institute of Evolutionary Animal Morphology and Ecology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 2, No. 6, pp. 627–635, November–December, 1970.     

Collection of Free-Living Nymphs and Adults of Amblyomma Hebraeum (Acari: Ixodidae) with Pheromone/Carbon Dioxide Traps at 5 Different Ecological Sites in Heartwater Endemic Regions of South Africa

The capture of free-living adults and nymphs of Amblyomma hebraeum, the main vector of heartwater in domestic and wild ruminants in South Africa, by means of attraction–aggregation–attachment–pheromone/carbon dioxide traps at five endemic localities in South Africa is described. Although the traps were used successfully at each of the localities, no determination of their efficiency in relation to the actual abundance of ticks at a particular site was made. This study confirmed that the traps could be used in a variety of ecological areas to locate populations of free-living adult A. hebraeum.     

Sensory cells in the head skin of pond snails

Summary Several types of receptor endings were identified with scanning electron microscopy and silver-impregnation techniques in the skin of the tentacles, lips, dorsal surface of the head and mouth region of the pond snails Lymnaea stagnalis and Vivipara viviparus. Sensory endings at the tips of dendrites of primary receptor neurones, scattered below the epithelium, differ in structure, i.e., the endings exposed to the surface of the skin possess different proportions of cilia and microvilli, which vary in number, length, and packing. Type-I endings have microvilli and a few (1–5) cilia, 5–12 m in length. Type-2 endings have abundant (20–40), interwoven long (9–12 m) cilia and random microvilli. Type-3 endings show typical packing of 10–25 cilia in the form of bundles or brushes. They may be composed either of long (9–18 m) or short (2–7 m) cilia, or of both long and short ones. Microvilli here are absent. Type-4 endings have only microvilli. Two other types of skin receptors do not extend their sensory endings to the surface and can be indentified only in silver-stained preparations. Type-5 endings are branching dendrites of skin receptors cells that terminate among epithelial cells. In type-6, the sensory endings also terminate among epithelial cells but their cell bodies are located outside of the skin. In both species all skin regions examined possess the receptors of all six types differing only in their relative proportion. Possible functional roles of different receptors are discussed.     

Biology ofChironomus piger Str. (Diptera: Chironomidae) and its role in the self-purification of a river

Chironomus piger larvae are widespread in small rivers and canals strongly polluted with domestic sewage. Despite this, almost nothing is known concerning the biology of the species under natural conditions and its role in the process of river self-purification. For two years, benthic samples were collected in the Sestra River at a site about 250 m downstream of the effluent discharge drains of a sewage treatment installation where the greatest concentrations of the larvae occurred. The number and biomass ofC. piger larvae were subject to marked fluctuations,viz. 96,000–348,000 ind m^–2 and 420–1,800 g m^–2. 460 degreedays (on average) was required for development of one generation.C. piger has 5 or 6 generations per year depending on the hydrometeorological conditions during the growing season.C. piger larvae play an important role in self-purification of the river. They utilize precipitating seston for food and for building their dwelling tubes. According to our calculations the amount of organic matter assimilated in the area of maximum larval concentration ranged 80–177 g wet weight m^–2 day^–1, and 32–71 g wet weight m^–2day^–1 was mineralized.     

Prevalence of superficial mycoses in the Aosta Valley Region of Italy from 1984 to 1989

Two hundred and thirty soil samples from different localities were examined for the presence of geophilic keratinophilic fungi. Six species namely Microsporum gypseum — 34 isolates, Chrysosporium keratinophilum –29, C. tropicum –20, Keratinophyton terreum –4, Trichophyton terrestre –8 and Chrysosporium species – 3 — were isolated. Most of these fungi were recovered from garden, field and river bank soil. The importance of these findings is briefly discussed.     

Radiocesium decay in populations of brown trout and Arctic char in the alpine Atna area, south-eastern Norway

Some of the highest recordings of radioactive fallout from the Chernobyl accident in Norway were found in the south-eastern Oppland and Hedmark counties. Cesium content and decay rates were followed in populations of brown trout and Arctic char in Lake Atnsjøen over the years 1986–1995. These results were compared with samples for adjacent lakes to test for between-lake variabilities within the same region. The data on brown trout was compared with samples from a wider region, where more than 1800 individual samples of brown trout were collected from nearly 100 localities. Back-calculated initial activity per 1 January 1987 showed a strong regional and within-lake variability for these localities, ranging from 437 to 18000 Bq kg^–1 (average: 2416 Bq kg^–1), while trout and char from Atnsjøen had initial activities of 1259 and 1122 Bq kg^–1, respectively. Most of the other populations from the Atna region also had initial activities below the average (around 2000 Bq kg^–1). Ecological half-life for both brown trout and Artic char in lake Atnsjøen was close to 1.7 years (corresponding to a decay rate of 0.4 year), which was consistently lower than the 2.5 years average for the entire lake data set. Decay constants from linear regressions of total decay over time ranged from 0.15 to 0.28. For trout populations, a positive correlation was found between initial load and decay constants. Although trout and char clearly differ in their diet, no consistent differences were recorded in initial activities or decay rates for these two species in the Atna area.     

Patterns of distribution and abundance of large brown algae and invertebrate herbivores in subtidal regions of northern New Zealand

The distribution and abundance of subtidal laminarian and fucoid algae, echinoids, and four species of herbivorous gastropods were assessed. Line transects and stratified random quadrats were used, encompassing different depths and seven localities ranging over 1000km in northern New Zealand. This sampling was carried out to form a quantitative basis on which to pose hypotheses for later experimental work. Several patterns were apparent, both within and between localities. Fucoid algae were characteristic of depths between 0–6 m, while laminarian algae had peaks of abundance at 3–6 m and from 10–17 m. Intermediate depths were characterized by areas bare of large brown algae, with high densities of echinoids and gastropods. This pattern of a bimodal depth distribution of algae and abundant grazers at intermediate depth was a consistent feature of the northern coastal sites and the semi-exposed offshore islands. Size—frequency distributions for algae at these sites showed that the largest fucoids generally occurred in very shallow water, while the dominant laminarian alga tended to have larger individuals at depths of 10–14 m. In all cases, the biomass distribution with depth of the algal species mirrored their numerical abundance.

Differences between localities were associated both with environmental factors and the unique algal floras of some offshore islands. Echinoids and gastropods were rare at the two most exposed localities, which were also at the extremes of the geographic range. At these sites, depths between 6–10 m were occupied by large brown algae. Deep-water fucoid algae occurred at two offshore localities but the predominant species at one of them was peculiar to that island group.

Because of the general consistency between localities, and the few exceptions to these patterns, hypotheses are considered which could be tested on a local scale to account for echinoid and algal abundances and depth distributions. Our results indicate that the chief questions concerning the structuring of subtidal algal communities are demographic in nature and that an assessment of the status of individual organisms, rather than biomass or productivity, is the appropriate approach to resolve these questions.     

A quantitative scuba-diving survey of the sublittoral macrobenthos at subantarctic Marion Island

Summary A SCUBA-diving survey of the macrobenthos of hard substrata in the sublittoral zone at subantarctic Marion Island was conducted during March and April 1988. Dense beds (12 kg m^–2) of the kelp Macrocystis laevis occur in depths > 5 m. Durvillaea antarctica is found along the infralittoral fringe and Desmarestia rossi and Durvillaea sp. occur in a narrow zone from 3 m–6 m. Under-storey algae (chiefly rhodophytes) tend to decrease in biomass with depth, with mean values of 1.57 kg m^–2 at 5m, 0.75 kg m^–2 at 10m and 0.49 kg m^–2 at 15 m. Encrusting coralline algae are particularly abundant in shallow areas (¯x = 0.92 kg m^–2) but are insignificant in deeper areas. Total biomass of macrozoobenthos increased with depth with mean values of 0.12 kg m^–2 at 5 m, 0.34 kg m^–2 at 10 m and 0.46 kg m^–2 at 15 m. Polychaetes, crustaceans, echinoderms, molluscs, sponges and bryozoans dominated the macrozoobenthos in terms of biomass. Approximately 200 species of macrobenthic animals were recorded and numerically, polychaetes, crustaceans, molluscs, nematodes and echinoderms dominated. The sublittoral benthos at Marion Island is compared with that occurring at other subantarctic and Antarctic islands, in particular, the Kerguelen Island group. Zoogeographic trends and the possible effects of nutrient input from seabird guano are briefly discussed.     

Search for possible latitudinal ecotypes inDumontia contorta (Rhodophyta)

Effects of daylength and temperature on the formation of erect fronds (macrothalli) from crusts (microthalli) ofDumontia contorta (S. G. Gmel.) Rupr. from three localities in Nova Scotia and one locality in Southern Iceland were investigated and compared to such effects shown by strains from three different East Atlantic localities (Isle of Man; Zeeland, S. W. Netherlands; and Roscoff, Brittany, France). Although these strains showed small differences in their temperature-daylength responses, these could not be interpreted as latitudinal adaptations, and consequently no latitudinal ecotypes could be found forDumontia contorta in the N. Atlantic Ocean. Upright fronds are formed at a broad temperature range of about 4°–18°C and at daylengths 13 h. Only in the southernmost part of its distribution area can high autumnal temperatures be expected to block the reappearance of upright fronds after passage of the critical daylength in September. In the larger part of the distribution area even summer temperatures are not high enough to block formation of uprights and here apparently only short daylengths initiate the reappearance of young upright fronds in autumn. The consequences of these aspects of the life history regulation for the geographic distribution are discussed.Paper presented at the Seaweed Biogeography Workshop of the International Working Group on Seaweed Biogeography, held from 3–7 April, 1984 at the Department of Marine Biology, University of Groningen, The Netherlands. Convenor: C. van den Hoek.     

The influence of coastal upwelling on the distribution of Calanus chilensis in the Mejillones Peninsula (northern Chile): implications for its population dynamics

A field experiment was carried out in October 1998 during active upwelling in a coastal area off the Mejillones Peninsula (23° S). Zooplankton was sampled at day and night, during two subsequent days at 4 stations inside and outside of the upwelling plume. Three depth strata were sampled: 0–20 m, 20–80 m and 80–200 m. Oceanographic data were obtained in a grid of 23 stations using a CTDO, a fluorometer and a Doppler current meter. Calanus chilensis was mostly represented by late stages, i.e. copepodid C5 and adult males and females. There were no day/night effects on vertical distribution, and abundance was significantly higher inside the upwelling plume in the upper 20-m layer at nearly 14 ind. m^–3, compared to ca. 5 ind. m^–3 outside the upwelling plume. Temperature at 10 m depth and biomass, estimated from stage numbers and their mean dry weights, were used to estimate growth and daily production of Calanus at temperature-dependent rates. The potential loss of biomass from the upwelling center because of advection in the upwelling plume was estimated from current data in the Ekman layer and biomass density. The mean cross-shelf component of the current was estimated at 10.4 km d^–1 within the upwelling plume. This yielded a loss of biomass of 9.7 mg dry weight m^–2 . Production, estimated by a temperature-dependent approach, ranged between 44 and 35 mg dry weight m^–2 d^–1, at mean temperatures of 14.6 °C and 15.8 °C inside and outside of the upwelling plume respectively. Within the plume, as much as 22% of daily production may be advected offshore. However, a higher concentration of biomass in the upwelling plume allowed a greater production compared to surrounding areas. A mass balance approach suggests that advective losses may not have a major impact on the C. chilensis population, because of very high daily production at temperature-dependent rates.     

Denitrification in the water column of an intermittently anoxic fjord

Denitrification was studied in the water column in the Bunnefjord, inner part of the Oslofjord in southern Norway, using a ¹⁵N-technique (the isotope pairing method). The fjord is 150 m deep and during our surveys in September–December 1998 hydrogen sulphide was present in the deep water below 80 m. No significant denitrification was found in water samples from the surface layer (4 m depth), but high rates were observed within a deep density gradient between 62 and 78 m depth. Oxygen concentration within this layer was low (<21 mmol m^–3), and the concentration of NO₃ decreased from ca. 15 mmolm^–3 at 62 m depth to not detectable below 78 m. Pronounced peaks of NO₂ up to 4.4 mmol m^–3 were observed at 70–78 m depth. The maximum denitrification rate of 1.5 mmol N m^–3 d^–1 was observed at 70 m depth. Integrated for the whole layer, the denitrification rate was 13 mmol N m^–2 d^–1. A significant linear correlation was found between the denitrification rate and the ambient nitrate concentration which indicated that the rate was primarily controlled by the availability of nitrate in the O₂-poor water. Compared to rates reported for coastal water, denitrification in the water column in the Bunnefjord was high and the process appears to be a major sink of bioavailable nitrogen in the fjord.     

The latitude-elevation relationship for spruce-fir forest and treeline along the Appalachian mountain chain

Spruce-fir forests extend along the Appalachian Mountains of eastern North America from 35° to 49° N. This montane vegetation differs from boreal spruce-fir forest in that it is dominated by Picea rubens, has a higher vascular species richness, has wind, rather than fire, dominated dynamics, and has a mean annual temperature above 2 °C. Using field reconnaissance, remote sensing, and literature review we described and modeled the latitude-elevation relationship for Appalachian spruce-fir. The elevation of the sprucefir/deciduous forest ecotone decreases from 1,680 m at 35° N to 150 m at 49° N, while the elevation of treeline (spruce-fir/tundra ecotone) decreases from 1,480 m at 44° N to 550 m at 55° N. Linear regressions gave latitude-elevation relationships of –100 m/l^o Latitude for the spruce-fir/deciduous forest ecotone and –83 m/l^o Latitude for treeline. These values compare to literature reports of –54 to –230 m/l^o Latitude and are most similar to values reported from eastern Asia. The latitude-elevation relationship for eman July temperature ( –94 to –121 m/l^o Latitude) was more similar to the slopes of these ecotones than is the slope for mean annual temperature ( –170 to –220 m/l^o Latitude). The spruce-fir/deciduous forest ecotone was correlated with a mean July temperature of approximately 17 °C. Treeline was correlated with a mean July temperature of approximately 13 °C.     

Myxidium lesminteri n. sp. (Myxosporea: Myxidiidae) from the gall-bladder of three southern African Anura

During 1988 and 1989 409 specimens, representing 50 species in 9 families of southern African Anura from 26 localities throughout the Republic of South Africa and from Swaziland, were examined for gallbladder myxozoans. Myxidium lesminteri n. sp. was the only myxozoan found and was observed in one tomopterna krugerensis (Ranidae), one Bufo garmani (Bufonidae) and one Heleophryne natalensis (Heleophrynidae), all from Transvaal. The spore of Myxidium lesminteri (9.5–15.0 × 5.0–8.0 m) is characterised by a smooth shell devoid of striations but has one longitudinal ridge.     

Methane Content in the Bottom Sediments and Water Column of the Black Sea

The methane content in the bottom sediments and water column of the Black Sea was determined using various methods of desorption and analysis of gases and various methods of calculating their concentrations. The head-space method with the use of salting out and calculation by an internal standard proved to be the most accurate procedure for the analysis of methane concentration in bottom sediments. The methane content in bottom sediments increased downward along the sediment thickness. In the upper 50–70 cm of shelf sediments, two minimums of methane concentration were revealed; in deep-sea sediments, only one minimum was recorded (in the 20–50 cm horizons). In the water column, methane concentrations slowly grew from the surface to a depth of 150–200 m and abruptly increased to a depth of 700–1200 m, remaining virtually constant in underlying layers. In certain deep-sea regions, peaks of methane content in the 1000–1200 m horizons of the water column were revealed, which were most probably due to local influx of abyssal waters enriched with this gas.     

Observations of Lophelia pertusa and the surficial geology at a deep-water site in the northeastern Gulf of Mexico

Authigenic carbonate, precipitated in conjunction with biogeochemical activity associated with hydrocarbon and related fluid seepage, provides exposed and buried hard substrate on the crest and flanks of a low-relief mound located on the upper De Soto Slope in the northeastern Gulf of Mexico. Lophelia pertusa has successfully colonized some of this carbonate material. Individual colonies range in size from a few centimeters to over 1.5 m in diameter while aggregations of closely associated colonies with linear orientations were observed to attain 1.5–2 m in height and width and 3–4 m in length. Many of the aggregated colonies appear to be in the first phase of the `thicket' building stage described by Squires (1964). Colonies less than 50–75 cm in diameter were nearly always completely pure white. Larger colonies and the aggregated colonies are often light to dark brown in coloration at their base and center with many having only white terminal branches and some with no white corallum at all.