Reproductive cycles of Mytilus edulis L. on the west and east coasts of Iceland

Studies evaluating the reproductive pattern of Mytilus edulis L. were conducted in western and eastern Iceland at two sites at about the same latitude but with different temperature regimes. Mussels were sampled once or sometimes twice a month during two years in Breidifjördur, western Iceland and one year at Mjoifjördur, eastern Iceland. Gonad development was monitored by microscopic observation of thin sections of the gonads. The initiation of gonad development was observed in January in Breidifjördur while in Mjoifjördur some of the animals started developing gonads in October, a month before spawning was over in the population. Spawning started in late June or July, peaked in August and continued until November at both sites. Nutrient reserve stores seemed to be limited and used for initiation of gonad development in winter but were not sufficient for maturation of the gonads. The main growth of the gonads occured in spring in conjunction with phytoplankton blooming and renewal of food resources.     

Inferring erosional resistance of bedrock units in the east Tennessee mountains from digital elevation data

Measures of local relief, regional relief, and slope were calculated from digital elevation models (DEMs) for 50 bedrock units in the Ridge and Valley and Blue Ridge provinces of Tennessee. Each of these measures was normalized and the three were then averaged to produce the erosional resistance index (ERI). Bedrock units with higher ERI values include coarse clastics, intermediate clastics, and metaplutonics. Units with lower values include shales, limestones, limestones plus dolostones, and carbonates plus fine clastics. Dolostones tend to have intermediate values. The calculated ERI values were compared with subjective ratings by a geologist with decades of field experience in east Tennessee. Generally, the agreement between the two ratings was good, the most glaring exception being several shales with improbably high ERI values. These turned out to be thin units cropping out beneath very hard sandstones, allowing them to stand higher and steeper than would otherwise be possible. A systematic method for detecting such erroneously high ERI values is suggested. Inspection of a drainage map superimposed on the geology map shows that in a given area, streams tend to flow on rock units with the lowest ERI values. In addition, statistical analysis shows that bedrock units with the lowest ERI values are, on average, almost three times closer to the nearest stream and six times as likely to have streams flowing on them than are units with highest values. Further, the effect of ERI on stream location is strongest for streams with drainage areas between 1 and 30 km². Thus, small streams appear to be subject to greater lithologic control than are larger streams.     

Habitat, occurrence and conservation of Saharo-Arabian-Turanian element Forsskaolea tenacissima L. in the Iberian Peninsula

The aim of this study is to assess the Iberian populations of Forsskaolea tenacissima L. according to its biogeographical interest, habitat, geographical range and conservation status. Results point out that they are restricted to gravel wadis of Tabernas Desert (SE Spain), are scarcely included in protected areas and represent historically isolated populations with relict behaviour. We also describe a new association, Senecioni-Forsskaoleetum tenacissimae. Conservation status of species is cause for concern and two conservation actions must be carried out. Firstly, protected areas should house Forsskaolea populations and secondly, phytosociological characterization of a community allows inventorying its habitat and directing conservation efforts to community level.     

Modeling Lake Ladoga Zoobenthos and Studying Its Role in Phosphorus Exchange at the Water–Bed Interface

A zoobenthos submodel is included in an ecosystem model. The new model is used to assess the role of zoobenthos in the phosphorus exchange at the water–bed interface, in particular, the phosphorus cycle in the water body ecosystem is described more accurately. The calculated zoobenthos distribution over the bed of a lake can be used in modeling the lake ichthyocenoses.     

Haze Research in Brunei Darussalam During the 1998 Episode

— Brunei Darussalam experienced a severe haze episode between the beginning of February and the end of April 1998 due mainly to local peat and forest fires in Brunei and in neighbouring Sabah and Sarawak. The extensive research studies of the haze carried out in Brunei are outlined together with selected results. Particulate matter (PM₁₀) was the only significant criteria pollutant and it exceeded WHO guidelines and accepted air quality standards on most days during the haze episode. Gaseous criteria pollutants (CO, SO₂, NO₂, O₃) were generally well below WHO guidelines and at these concentrations they are expected to have no significant health or environmental effects. Measurements of volatile organic compounds (VOCs) revealed the presence of benzene, toluene, ethylbenzene, and xylenes (BTEX), aldehydes, phenol, and polynuclear aromatic hydrocarbons (PAHs). Personal exposure monitoring of PM₁₀ revealed significant differences in exposure patterns between different individuals depending on the location, time and activity. Data on outpatient visits showed an increase for some illnesses (e.g., acute respiratory infection) during the months of haze. No significant impacts of haze on rainwater acidity or deposition were noted. Emission factors for some volatile compounds were determined in combustion experiments in which peat was burned at temperatures typical of smouldering.