<Emphasis Type="Italic">Alona alsafadii</Emphasis> n. sp. from Yemen,a primitive,groundwater-dwelling member of the <Emphasis Type="Italic">A. karua</Emphasis>-group

The effect of algae on the production of musty-smelling compounds by actinomycetes was studied. Streptomyces spp., causing intensive musty odor, were isolated from hypertrophic Lake Kasumigaura and cultured in association with algae from the same lake. Isolate E and I effectively utilized the cyanobacteria, Microcystis aeruginosa and Anabaena spiroides, and the diatom, Synedra acus, as a carbon source and produced a musty-smelling 2-methylisoborneol in the shaken sediment cultures. High populations of algae and actinomycetes, and aerobic condition in the sediment seem responsible for the occurrence of musty odor in Lake Kasumigaura.     

Paleolirnnological records of carotenoids and carbonaceous particles in sediments of some lakes in Southern Alps

Stratigraphic analyses of organic carbon, organic nitrogen and algal and bacterial carotenoids in short cores of profundal sediments of four alpine lakes (Tovel, Leit, Paione superiore and Tom) were used to reconstruct their trophic history. In addition, depth distribution of carbonaceous particle concentrations provided information on lake contamination from atmospheric deposition. In three lakes (Tovel, Leit and Tom), sedimentary carotenoids unique to sulfur photosynthetic bacteria (okenone and isorenieratene) provide evidence of changes in the oxygen, light and sulfide conditions in the water column. All the lakes are oligotrophic or moderately productive, and the algal community is dominated by Chlorophyta, Pyrrhophyta and Cryptophyta. Cyanobacteria are rather poorly represented. The steep increase of carbonaceous particles in the uppermost sediment layers of all the lakes suggests that lake contamination by atmospheric transport of pollutants began in the 1940s to 1950s. These data, coupled with those from a parallel study on Chrysophycean scale-inferred pH, indicate recent acidification in those which are poorly buffered (Paione superiore and Leit).     

Measurement of organic-35S and organic-S in lake sediments: Methodological considerations

Three protocols for the determination of inorganic and organic sulfur fractions were tested for their suitability to estimate total indigenous organic sulfur (S_org) and³⁵S_org formed from added³⁵SO₄ ^2– in sediments of chemically dilute lakes in the ELA. The protocols tested have all been reported in the literature. It was found that two protocols involving sequential analyses for S fractions following acid treatment gave estimates of both S_org and³⁵S_org up to 87% lower than a non-sequential protocol. The low estimates were largely due to hydrolysis and solubilization of solid phase S which was then removed in a rinsing step. The non-sequential protocol, in which total reduced inorganic sulfur and total sulfur were determined on separate aliquots, is recommended as the most reliable of the three. Individual analyses in this protocol were verified for these lake sediments using a variety of S standards.     

Sediment toxicity in the Kattegat and Skagerrak

Sediments were sampled from 62 sites in the Kattegat and Skagerrak, which are located between the Baltic and the North Sea in the Western Atlantic, during autumn 1989 and spring 1990. From each site 5 to 6 samples were taken wit ha box-corer. After mixing to composite samples on board, transport and storage (at 4 °C for 2 to 4 weeks), the samples were tested for toxicity to Daphnia magna and Nitocra spinipes. Immobility in Daphnia after exposure to 16 percent sediment (wet wt) in reconstituted standardized water (ISO, 1982) ranged from 0 to 88 percent after 24 h and from 3 to 95 percent after 48 h. For Nitocra the toxicity, determined as the 96-h LC50 (% wet wt) at 7 salinity, ranged from > > 32 percent (nontoxic) to 1.8 percent (most toxic). All exposures were made in duplicates and the effects obtained in the duplicates with the same sediment were correlated to each other. However, sediment toxicity to Daphnia and Nitocra was not. The test with Nitocra, which was made at several concentrations of sediment, was considered to give the most reliable picture of sediment toxicity in the Kattegat and Skagerrak. This ambient toxicity assessment identified three areas with toxic sediment, (1) the Göta älv estuary (outside the city of Göteborg) and its surroundings, (2) the Bay of Laholm in southern Kattegat, which is an area with periodic oxygen depletion and where repeated mussel kills have occurred during the last decade, and (3) an area in the open Skagerrak northwest of Skagen (the tip of the Jutland peninsula). Sediments, which had been stored at 4 °C, were tested again after 6 to 13 mos with the Nitocra test. Stored sediment toxicity was poorly correlated with fresh sediment toxicity. The average detoxification during storage was 5 times, but the range was 3 orders of magnitude, from 17 times more toxic to 73 times less toxic. The reasons for the observed areal and storage differences in sediment toxicity are so far not understood.     

A new approach for testing contaminated marine sediments: fertilization success of lugworms following parental exposure

A sediment bioassay is being developed using several marine benthic invertebrates to assess the effects of parental transfer of contaminants to the gametes. In this preliminary study, the emphasis was placed on developing methods for the in vitro fertilization of lugworm, Arenicola marina, oocytes.Lugworms exposed to contaminated sediments in outdoor mesocosms were brought to the laboratory, just before the beginning of the spawning period. The reliability of an in vitro fertilization procedure was tested by varying several parts of the method. Main results are that eggs and embryos may be physically damaged by cleaning over a sieve. However, as no negative effects were observed when leaving eggs and sperm together for 24 h, the sperm need not be washed off until the embryos are preserved for further examination later on.A first, incomplete screening of the effects of contaminated harbour dredged sediments indicated some effect on the reproductive success.     

A newCercophora with aChrysosporium-like anamorph

A new species ofCercophora, isolated from river sediment collected from Sakai River in Nagasaki Prefecture, Japan, is described and illustrated. It is distinguished from the other knwon species by the morphology of its ascomatal peridium and ascospores, and by itsChrysosporium-like anamorph.     

Seasonal variations of P compounds and their concentrations in two coastal lagoons (Herault,France)

This article concerns seasonal variations in the phosphate concentrations in two coastal lagoons near Montpellier (Mediterranean coast, France). The o-P concentration in the overlying water is highest during summer. The role of the sediment, particularly that of the different P fractions in the sediment, is discussed. Significant variations, especially in the FeOOH ≈ P fraction, occur. For both Tot-P_sed and the Fe00H≈P fraction a gradient from surface to bottom is observed, as well as a distinct decrease in the FeOOH≈P fraction in the surface sediments during summer and autumn. Variations in the FeOOH≈P fraction appear to be compensated by variations in the CaC0₃≈P fraction. These variations appear to be determined by the ferric hydroxide concentration. This compound represents only a small part (maximally 15%) of the total iron in the sediments and is related to the dissolved oxygen content of the immediately overlying water. Besides the fractions o-P, Fe(OOH)≈P, a large part of the CaC0₃≈P fraction is potentially bioavailable. A large proportion of the Tot-P_sed is therefore bioavailable.[/p]     

Eutrophication and recovery of Lake Vesijärvi (south Finland): Diatom frustules in varved sediments over a 30-year period

Lake Vesijärvi was loaded by sewage from the City of Lahti for 60 years until 1976 when the discharge was diverted. Paleolimnological analyses of the varved bottom sediment indicate that the sedimentation rate within the Enonselka basin, the most eutrophic part of the lake, has been as high as 2 cm yr^–1, and total phosphorus accumulation was 20–40 g P m^–2 yr^–1, during the last 20 years. Within the less eutrophic Laitialanselkä basin, the sedimentation rate did not exceed 1 cm yr^–1, and the formation of varved sediment only began at the end of the 1960's, i.e. about 10 years later than in Enonselkä.Planktonic diatom production was highest in the Enonselka basin. The most abundant diatoms in the sediment between 1970–1985 were Asterionella formosa, Aulacoseira islandica and Stephanodiscus spp. Fragilaria crotonensis and Tabellaria fenestrata had low abundances in the middle of the 1970's but increased again at the end of the 1970's. Asterionella formosa and Diatoma elongatum reached their maxima between 1979–1984 when the hypolimnion of the Enonselk/:a basin was aerated artificially. In the Laitialanselkä basin, the production of planktonic diatoms has been lower and the species composition of the diatom community differed from that in Enonselkä. However, at the end of 1980's the total accumulation of diatoms in Laitialanselkä approached levels which were observed at the end of 1950's in Enonselkä, prior to the rapid eutrophication period.The production and thereby the sedimentation of diatoms has decreased towards the end of the 1980's in Enonselkä, indicating reduced nutrient availability in the lake water. This reduction was due to the decreased external loading of phosphorus as well as to the decreased release of phosphorus from the sediment as a result of improved oxygen balance in the hypolimnion.     

Iron content of sediment and phosphate adsorption properties

Phosphorus can occur in sediments in different forms and accordingly its availability varies. The distinction between the phosphorus fractions is made with two chemical extraction methods; an ammonium oxalate-oxalic acid extraction and an extraction according to Hieltjes & Lijklema (1980).The iron and aluminum liberated with the ammonium oxalate-oxalic acid extraction method is linearly correlated (r ² = 0.73) with the phosphorus liberated in the first two steps of the Hieltjes and Lijklema extraction by: P = 0.035 (Fe + Al) + 0.001 (P, Fe and Al in mmol g^–1).The iron and aluminum (hydr)oxides are very important fractions in the sediment adsorption capacity for phosphorus. The phosphorus sorption capacity (PSC) is 0.080 mol P (mol (Fe + Al))^–1 and the adsorption constant (k) is 11.9 µmol P l^–1. Here it is assumed that iron and aluminum (hydr)oxide have the same affinity for phosphorus.     

Short-term effects of a large dam decommissioning on biofilm structure and functioning

Aging dams and the rising efforts to restore stream ecosystems are increasing the number of dam decommissioning programs. Although dam decommissioning aims at improving in-stream habitat, biodiversity, and ecosystem functioning in the long term, it might also cause ecological impacts in the short term due to the mobilization of the sediment accumulated in the reservoir. Benthic biofilm in particular can be impaired by episodes of high turbidity and scouring. We conducted a multiple before-after/control-impact experiment to assess the effects of the drawdown of a large dam (42 m tall), a first step to its decommissioning, on biofilm structure (biomass and chlorophyll-a) and functioning (metabolism, nutrient uptake, and organic matter breakdown). Our results show that the reservoir drawdown reduced the autotrophic biofilm biomass (chlorophyll-a) downstream from the dam, which in turn lowered metabolism. However, nitrogen and phosphorus uptake by the biofilm was not affected. Organic matter breakdown was slower below the dam than in nearby undammed reaches before and during drawdown. All drawdown effects quickly disappeared and reaches downstream from the dam approached values found in nearby undammed reaches. Thus, our results indicate that the effects of reservoir drawdown on stream biofilms exist but may be small and disappear rapidly.