Karyological Studies of Biomphalaria tenagophila (d'Orbigny, 1835) (Gastropoda: Planobidae) from Rio de Janeiro,Brazil

The karyotypes of Biomphalaria tenagophila collected from Rio de Janeiro, Brazil were studied using the air-drying method. Somatic cells of this species had 2n=36. The 18 chromosome pairs were identified and classified into 3 groups. The diploid cell has 7 pairs of metacentric, 8 pairs of submetacentric, and 3 pairs of subtelocentric chromosomes. Observed chromosomes ranged from 2.4 to 6.4 µm, and the total length was 122.3 µm. This is the first report on the chromosome of B. tenagophila.     

Molluscicidal activity of Physalis angulata L. extracts and fractions on Biomphalaria tenagophila (d'Orbigny, 1835) under laboratory conditions

The main objective of this research is to evaluate the molluscicide activity of Physalis angulata L. Biomphalaria tenagophila specimens under laboratory conditions. Extracts and fractions were supplied by the Laborat rio de Qu mica de Produtos Naturais, Farmanguinhos-Fiocruz. Experiments were performed according to the methodology described by the World Health Organization for molluscicide tests using the concentrations from 0.1 to 500 mg/l of the extracts, fractions and of a pool of physalins modified steroids present in this species. The results show that ethyl acetate and acetone extracts from the whole plant, the ethanolic extracts of the roots and the physalins pool from stems and leaves were active. Only the whole plant extracts were available in sufficient quantity for the determination of LD50 and LD90 values.     

Heavy metal and other trace elements in native mussel Diplodon chilensis from Nothern Patagonia Lakes, Argentina

Native mussels, Diplodon chilensis, were sampled from four lakes in Nahuel Huapi National Park, Northern Patagonia, Argentina in order to evaluate heavy-metal distribution in the region and to assess the contribution of this compartment of the trophic web to their circulation in the food chain. The concentration of potential pollutants Ag, As, Cr, Hg, Sb, and Se, and other nine elements of interest (Ba, Br, Ca, Co, Cs, Fe, Na, Sr, and Zn) were determined in Diplodon chilensis pooled samples. Digestive glands were analyzed separately from soft tissues. Geological tracers Sc, Ta, Th, and rare earth elements were also determined in order to discriminate lithophile contributions. Elemental concentrations of Ba, Br, Fe, Sr, Se, and Zn in total soft tissues samples do not show significant differences among sampling sites. Arsenic and Cr contents in total soft tissues and digestive gland pooled samples are higher in sampling points close to zones with human settlements. Silver contents in samples collected in Lake Nahuel Huapi were higher than in the other lakes studied, and up to 50-fold higher than the sample collected in Lake Traful, considered as the reference. Mercury highest concentration values measured in total soft tissues pooled samples from lakes Nahuel Huapi and Moreno were found to be similar to those observed in other reported Hg contamination situations, and they are three to five times higher than those of the reference samples collected in Lake Traful.     

Oxidative stress and histological alterations produced by dietary copper in the fresh water bivalve Diplodon chilensis

The aim of this work was to study the oxidative stress effects and histological alterations caused by dietary copper on the filter-feeding freshwater mussel Diplodon chilensis. Bivalves were fed during 6 weeks with the green algae Scenedesmus vacuolatus previously exposed to copper. Metal concentration in algae cultures and bivalve digestive gland was measured by TXRF. A maximum accumulation of 0.49 μg Cu/mg protein was detected at week 6. Also at this week, the hepatosomatic index (HSI) showed the highest decrease (50%) in response to Cu exposure. SOD and GST activities were significantly increased at weeks 4, 5 and 6, reaching an activity on average 50% higher than in controls for GST. CAT activity and GSH increased significantly at weeks 5 and 6. Despite this response, oxidative damage measured as TBARS and carbonyl groups contents increased significantly at weeks 4, 5 and 6, respectively. Digestive tubule and duct atrophy and cell-type replacement in treated mussels were observed by histological studies. The presence of intracellular rhodanine-positive granules, suggests copper accumulation in intracellular vacuoles of digestive cells.     

Seasonal variation in the diet of the king penguin (Aptenodytes patagonicus) at sub-Antarctic Marion Island

King penguins are important consumers of marine resources, throughout the year, at the Prince Edward Islands. Meal size varied from 8.5–12.6% of adult mass, depending on the method of determination. In spite of the biases in the analysis favouring the overestimation of squid, fish and, in particular, myctophid fish accounted for the largest proportion of the stomach samples, 87% by wet mass, 75% by numbers and 69% by reconstituted mass. The relative abundance of fish in the diet dropped markedly in winter followed by a subsequent rise to nearly 100% in summer. This rise coincided with an increase in the chick growth rate and the king penguin population at the island and suggests the rise in relative abundance offish reflects a real increase in the availability of fish around the islands.
Juvenile and adult Krefftichthys anderssoni/Protomyctophum tenisoni and adult Electrona carlsbergi were the most common fish consumed. There was an increase in the modal size of K. anderssoni/P. tenisoni throughout the year which we interpret as growth of a single fish population. Juvenile Kondakoviu longimana was the important squid species taken by king penguins. Crustaceans were only rarely recorded in the diet and may have come from digestion of fish and squid stomachs.
This is the first study of the diet of a Southern Ocean pelagic predator that has identified myctophid fish as a major component of its diet. All three important fish species taken by king penguins at Marion Island have a wide distribution throughout the Southern Ocean and consequently may prove to be important dietary components of other Southern Ocean pelagic predators.     

Seasonal reproductive periodicity in the male Australian Brush-tailed possum (Trichosurus vulpecula)

The reproduction of the possum, Trichosurus vulpecula (Kerr), was investigated on Banks Peninsula, Canterbury, from 1963 to 1965. The majority of births occur in the autumn, but there is a minor breeding season in the spring. After undergoing an anoestrous period during the summer most females enter oestrus around April. A small proportion of females give birth to a second young during September or October. Reproductive periodicity was also found to occur in the male possum. Although spermatogenesis continues throughout the year in the sexually mature animal there is a marked change in the size of the prostatic urethra at particular periods of the year which correspond to those in which the majority of females are undergoing oestrus. The mean weight of the prostate shows a sixfold increase during the autumn. However only very small changes take place in the size of the testis and epididymis. Changes in size and activity of the prostate correspond with marked changes in the interstitial tissue of the testis. Leydig cells, responsible for the secretion of testosterone, show a great increase in number in animals in which the prostate is enlarged. Associated with the growth of the prostate are changes in the behaviour of the possum. The body weight and fat deposits of the male possum drop markedly at the time of the autumn breeding season.     

Seasonal variations in sterol composition of Delesseria sanguinea (Ceramiales,Rhodophyta)

On Normandy coasts, the red alga Delesseria sanguinea perennates by its stipe; fronds grow in January and disappear in June. Seasonal variations in sterol composition in relation to the biology of D. sanguinea are reported. Sterols in cellular membranes are free or conjugated by esterification with fatty acids, heterosides or lipid complexes like phospholipids. Both kinds of sterols were analyzed by GC-MS. The major sterol (80%) found in fronds was cholesterol whereas in stipes, cholesterol was also the major sterol in spring, but in September, an important reduction in cholesterol yield was noted with proportional increase in sitosterol content. It appears that cholesterol is synthesized in fronds in spring, then transferred to the stipe, which loses an important amount of cholesterol with loss of the blades.     

Seasonal periodicity of aquatic fungi in tanks at Kurukshetra,India

The occurrence, distribution and seasonal periodicity of 49 species of aquatic fungi belonging to the orders Chytridiales, Lagenidiales, Blastocladiales, Saprolegniales and Peronosporales from two tanks of Kurukshetra, India, is described. Seasonal periodicity was found to be governed by temperature.     

Sexual Reproduction of the Foraminiferan Planoglabratella opercularis (d'Orbigny, 1839) in Nature

The taxonomic composition of the entire foraminiferan assemblage in the southern part of Peter the Great Bay (Sea of Japan) was studied during the summer 1999 expedition. Along with other foraminiferans, several offspring-filled tests of Planoglabratella opercularis (d'Orbigny, 1839) were found in surface sediment samples. Based on the extensive literature on the reproductive cycle of foraminiferans and indirect evidence, it was found that each of the parent individuals of this species was a partner in a plastogamous pair, thus being a gamont, while their offspring were agamonts. The gamogony stage, contrary to the generally accepted opinion, took place under natural conditions in summer (not in fall or winter) at a bottom water temperature of 15–18°C. The results of this research may be important in paleogeographical and paleoecological reconstructions.     

Seasonal periodicity of physical factors,inorganic nutrients and microalgae in Antarctic fellfields

Over 15 months between January 1990 and March 1991, a range of physical, chemical and biological parameters was monitored regularly in fellfield soils of frost-sorted polygons at four sites on Signy Island (South Orkney Islands, maritime Antarctica). These included inorganic nutrients (orthophosphate, available nitrate and, over a more limited period, ammonia), chlorophyll a (as a proxy measure of microalgal biomass) and a range of potential cryoprotectant compounds. Transects across soil polygons revealed neither intrapolygon gradients in concentrations of inorganic nutrients or chlorophyll a nor significant interpolygon differences, in contrast with previous studies. Nitrate was present in much lower concentrations than phosphate, supporting evidence that it is a limiting nutrient in these fellfield ecosystems. Spring snowmelt, although a potential source of nutrient input, was not associated with increased concentrations of inorganic nutrients in the soil, probably through isolation of the soil from overlaying snow by a surface layer of ice. Soil microalgae at the study sites must survive winter temperatures of at least −9°C, even when protected beneath up to 1 m of snow, and it has been proposed that they accumulate sugars and polyols as cryoprotectants. In support of this, concentrations of erythritol, glycerol, glucose, sucrose and trehalose in the soil (both absolute quantity and after correction for chlorophyll a concentration) increased as winter proceeded, suggesting that changes in sugar concentrations were due to accumulation within individual cells.     

Strain selection and genetic variation in Gracilaria chilensis (Gracilariales, Rhodophyta)

Strain selection processes in seaweed often have assumed that sterile clones could be maintained for long periods in a diversity of environments without major genetic changes. However, clonal species such as Gracilaria chilensis exhibit intra-clonal variation in performance and ongoing studies suggest such changes may be due to rapid changes in DNA composition associated with growth, via mitotic recombinations. Therefore performance of a given ramet in this type of seaweed should be understood as the dynamic outcome of rapid reactions between the environment and the changing genotype of the selected strain. To evaluate this idea, we measured changes in genetic variability, as detected by DNA-fragment polymorphism using RAPDs-PCR, exhibited by clones of G. chilensis after two transfers to different environmental conditions (from field to controlled laboratory conditions and from the laboratory to large-scale tank culture). The transfer to laboratory conditions reduced the frequency of low similarity values and increased the frequency of intermediate similarity values in DNA banding patterns, suggesting the branchlets produced under controlled laboratory conditions have less genetic variability (evaluated as total DNA polymorphism) than plants recently collected in the field. Tank incubation reduced the total range of similarity and significantly increased the frequency of high similarity values. Results thus suggest the dynamic of genetic changes in vegetative clones of Gracilaria chilensis that is fast and strongly affected by the external environment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Floristic composition and periodicity of subtidal algae on an artificial structure in port Phillip Bay (Victoria,Australia)

The subtidal macrobenthic algal flora on an artificial structure in northern Port Phillip Bay (Victoria, Australia) has been documented over a twelve-month period. The species composition was unlike any previously recorded from Port Phillip Bay and, of the sixty species, ten were new records for the region. Schottera nicaeensis (Lamour. ex Duby) Guiry & Hollenb., Stictyosiphon soriferus (Reinke) Rosenv., Medeiothamnion lyalli (Harv.) Gord. and Deucalion levringii (Lind.) Huism. & Kraft represent new Australian records and are considered likely to have been introduced on ships. The growth of most species varied seasonally, with maximum abundance and spore production occuring during late spring and summer. Species number reached its minimum in July (austral winter) and maximum in January (austral summer). Annual and pseudoperennial forms dominated the flora, and many species were only transient members of the community. The absence of perennial algae is attributed to the instability of the substratum caused by intermittent siltation and continual turnover of Mytilus edulis L. individuals, the major substratum for algal growth. Opportunistic species and species capable of vegetative perennation persisted through a continual process of recolonisation as free substrata became available.     

Seasonal periodicity of decapod larvae and population dynamics of selected taxa in New Hampshire (USA) coastal waters

Decapod larvae were collected during night-time hours at threestations off the New Hampshire coast during 1978–1980.Samples were analyzed for species composition and abundance.Life stages were identified for two species of carideans (Eualuspusiolus and Crangon septemspinosa) and two species of brachyurans(Cancer spp. and Carcinus maenas). Production and mortalityestimates were developed for Cancer spp., and C. maenas, andproduction estimates only were developed for C. septemspinosa.     

Integrated tank cultivation of salmonids and Gracilaria chilensis (Gracilariales,Rhodophyta)

In order to study the N and P balances in the Driss I reservoir, we measured concentrations in the water of these elements, their sedimentation rates, and their input by the river Inaouen and output through the dam. Supply and loss of N and P were calculated from samples collected every 48 hours and were for N 15 and 27. 5 mg m⁻² d⁻¹ and for P 33.6 and 1.1 mg m⁻² d⁻¹ respectively. The sedimentation rates, determined using sediment traps, were high, about 75 mg m⁻² d⁻¹ for N and 34 mg m⁻² d⁻¹ for P. Phosphate input came from point sources and was mainly in particulate form. A large fraction of the phosphate sedimented in the form of calcium bound phosphate, with some iron bound phosphate. Bioavailability was, however, low, as the particulate phosphate disappeared rapidly from the epilimnion because of the high sedimentation rate. The ratio Tot-N/Tot-P of the sedimented particulate matter varied between 0.05 and 7.74 and depended on primary production and watergate management.     

Seasonal species composition and distribution of barnacle larvae in Avacha Inlet (Kamchatka)

The annual dynamics of the numbers and distribution of barnaclelarvae in Avacha Inlet were studied. Planktonic cirripede larvaewere found in the area studied from late March at a temperatureof –1–0°C until October. The highest densityof 18 000 m^–3 was observed in mid-April. Balanus crenatusand Semibalanus cariosus were the dominant species, Chthamalusdalli and Balanus balanus larvae being less abundant. Naupliardensity was maximal at 0–5 m and decreased with depth.Maximum densities of B.crenatus larvae were observed in RakovayaBay, where there are many ships and a seawater-cooled powerstation. Most nauplii of the intertidal barnacle S.cariosus,which prefers wave-exposed open coast, were taken in the AvachaInlet narrows Settling on artificial substrata was most intensivefrom late May to early June     

Assessment of populations ofGracilaria chilensis (Graeilariales,Rhodophyta) utilizing RAPDs

Phenotypic variability and mixing of material due to massive cultivation for commercial purposes has contributed to the taxonomic confusion ofGracilaria in Chile. At least four species with cylindrical thalli and similar morphology have been recorded. However, since establishment ofG. chilensis, most of the collected thalli have been attributed to this species despite the lack of diagnostic features. In an attempt to resolve whetherGracilaria from 3 localities where it grows in natural and artificial populations belongs to the same species, gametophytic samples were compared by applying RAPD-PCR to their total DNA. This was analysed using 25 different 10-mer primers from which 21 revealed polymorphism within and between populations. Similarity matrices and cluster analyses were performed based on the presence/absence of bands representing fragments of DNA generated by random amplification. Similarity values between two of the populations were equivalent to those detected within a third, indicating the mixing of genetic material due to transplant between the two former localities. Similarities between samples of ChileanGracilaria andG. tenuistipitata from Sweden are considerably lower (0.45–0.53) than those between populations from Chile (0.74–0.88), confirming the existence of a single specific taxon,G. chilensis, in these three localities.     

Seasonal growth and reproduction in a highly fecund brachyuran crab, Metopograpsus messor (Forskal) (Grapsidae)

The annual cycle of a Metopograpsus population (Muzhupilangad estuary) had three distinct periods: (1) growth-reproduction (January–May), when crabs were involved in moult and reproduction; (2) inactive period (June–July), and (3) reproductive period (August–December). Usually, spawning was immediately followed by another vitellogenic cycle, paralleled by the embryogenesis of prehatch eggs in the brood. Moulting was seemingly an annual event. In the programming of moult and reproduction, the species deviated from the common brachyuran pattern, inasmuch as the postmoult females engaged in active vitellogenesis. The synchrony in the stages of maturation and spawning, and the precision with which the physiological events are programmed, make this highly fecund species an ideal model for an integrated study of the physiology of growth and reproduction.