Examination of data on North Wales soils shows that a good correlation exists between loss-on-ignition and organic C values, determined by Tinsley's method.Ignition for half an hour at 850° C, and for 16 hours at 375 f 5' C have both been employed. The latter has advantages over the former procedure. Regression lines and prediction limits for organic C from loss-on-ignition are given from the data obtained. Although these regressions are not necessarily expected to be generally applicable, examination of some published data suggests that closely similar expressions may be. The method, because of its simplicity, can be usefully applied in a wide range of survey, analytical, and ecological studies, in spite of the known sources of error.

The Coastal Zone Color Scanner (CZCS) on Nimbus-7, launched in October 1978, is the only sensor in orbit that is specifically designed to study living marine resources. The initial imagery confirms that CZCS data can be processed to a level that reveals subtle variations in the concentration of phytoplankton pigments. This development has potential applications for the study of large-scale patchiness in phytoplankton distributions, the evolution of spring blooms, water mass boundaries, and mesoscale circulation patterns.

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In this study we used catch and effort data from a commercial fishery to generate habitat suitability models for Port Phillip Bay, Victoria, Australia. Species modelled were King George whiting (Sillaginodes punctata), greenback flounder (Rhombosolea tapirina), Australian salmon (Arripis trutta and A. truttaceus), and snapper (Pagrus auratus). Locations of commercial catches were reported through a grid system of fishing blocks. Spatial analyses in a Geographic Information System (GIS) were applied to describe each fishing block by its habitat area. A multivariate approach was adopted to group each fishing block by its dominant habitats. Standardized catch per unit effort values were overlaid on these groups to identify those that returned high or low catches for each species. A simple set of rules was then devised to predict the habitat suitability for each habitat combination in a fishing block. The spatial distribution of these habitats was presented in a GIS. These habitat suitability models were consistent with existing anecdotal information and expert opinion. While the models require testing, we have shown that in the absence of adequate fishery-independent data, commercial catch and effort data can be used to produce habitat suitability models at a bay-wide scale.

The variability in pH, loss-on-ignition, exchangeable cations, extractable phosphate, and soil moisture, has been studied for the 0-15 cm horizon of uncultivated, unfertilized Brown Earths at two upland grassland sites in North Wales. The results show that there is a high degree of variability in samples taken at the same time on circles of I m radius at all sampling locations. For example, coefficients of variation for exchangeable cations (except sodium) average 33 per cent for twenty-two samples taken on the same occasion at three locations. This spatial variability prevented detection of any additional seasonal trends during a 22-week summer sampling period. It is essential to consider the importance of spatial variability in any pedological or ecological study.

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Calcareous volcanic ashes (pumice–tuffs) occur among Ordovician rocks in Snowdonia, North Wales. The clays of these rocks and of the ecologically important soils derived from them are found to be almost mono-mineralic and to consist of chlorites. Chemical, differential thermal and X-ray analyses are given and discussed with particular reference to a clay-size chlorite from weathered pumice–tuff. There is no evidence for pedogenetic clay mineral transformations in the range of soils studied.