A record of ductile syn-intrusional fabrics to post solidification cataclasis: Magnetic fabric analysis of neoproterozoic Mirpur and Mt. Abu Granitoids,NW India

The Mirpur granite body represents a relatively small (10 km²) pluton intruded along the northern margin of the adjacent Mt. Abu batholith (∼125 km²) in NW India. It is a visibly undeformed alkali feldspar rich pink granite; in contrast, the Mt. Abu is a composite granitoid body and variably deformed. Both are intruded by rhyolitic dykes and the terminal magmatic events in both the cases are mafic dykes. The AMS (Anisotropy of Magnetic Susceptibility) data identify the Mt. Abu with SE-dipping foliations and subvertical lineations as a single structural domain while the Mirpur granite body shows two domains characterized by predominantly E — W trend of magnetic foliation in the eastern part (domain I) and N — S orientations in the western part (domain II). The domain I shows magmatic fabrics, typical for the peraluminous granites of Malani Igneous Suite (MIS). Change in fabric orientation in the domain II has resulted from cataclasis wherein the samples show destruction of the original E — W fabric and complete transposition by N — S trends. The foliations in the Mt. Abu granites have been related to SE orientation of maximum horizontal stress. The same maximum stress direction can be inferred from dyke orientation in the Mirpur granite, which is interpreted as continuation of the tectonic imprint in this region during emplacement of both the granites. Age of the cataclastic overprint with a predominant N — S orientation is not yet constrained but corresponds with the trend of the nearby Sindreth basin within the Malani Igneous Suite. The Neoproterozoic tectonic scenario for the region has been interpreted in terms of an ongoing crustal convergence and granitic magma emplacement against the back stop offered by the rigid Delhi Fold Belt.     

Towards an expanded model of curriculum development and diffusion in education

The general model of the curriculum development process has been widely accepted as a satisfactory view of the process at work and of how the process might be made to work in practice. Such a model ignores the human element. The paper expands the general model so as to include the social interaction and interpersonal dynamics dimension of curriculum change. Concepts in diffusion theory and behavioural geography provide a perspective for building into the curriculum process views of it as a social system akin in some respects to a feudal society. The expanded model includes consideration of the influence of the social, personal, psychological and attitudinal traits of those engaged in curriculum development. The spatial pattern likely to be created by the model provokes questions about the best management of the diffusion process.     

Determination of Selenium Concentrations in NIST SRM 610, 612, 614 and Geological Glass Reference Materials Using the Electron Probe, LA-ICP-MS and SHRIMP II

A combination of EMPA, sensitive high resolution ion microprobe (SHRIMP II) and/or LA-ICP-MS techniques was used to measure the concentration of selenium (Se) in NIST SRM 610, 612, 614 and a range of reference materials. Our new compiled value for the concentration of Se in NIST SRM 610 is 112 ± 2 μg g⁻¹. The concentration of Se in NIST SRM 612, using NIST SRM 610 for calibration, determined using LA-ICP-MS (confirmed using SHRIMP II) was 15.2 ± 0.2 μg g⁻¹. The concentration of Se in NIST SRM 614, using LA-ICP-MS was 0.394 ± 0.012 μg g⁻¹. LA-ICP-MS determination of Se in synthetic geological glasses BCR-2G, BIR-1G, TB-1G and the MPI-DING glasses showed a range in concentrations from 0.062 to 0.168 μg g⁻¹. Selenium in the natural glass, VG2, was 0.204 ± 0.028 μg g⁻¹.     

Seasonal and Spatial Variations in Fish and Macroinvertebrate Communities of Oyster and Adjacent Habitats in a Mississippi Estuary

In Grand Bay National Estuarine Research Reserve (Grand Bay NERR), Mississippi, we used quantitative drop sampling in three common shallow estuarine habitats—low profile oyster reef (oyster), vegetated marsh edge (VME), and nonvegetated bottom (NVB)—to address the dearth in research comparing nekton utilization of oyster relative to adjacent habitats. The three habitats were sampled at two distinct marsh complexes within Grand Bay NERR. We collected a total of 633 individual fishes representing 41 taxa in 22 families. The most diverse fish family was Gobiidae (seven species) followed by Blennidae and Poeciliidae (three species each). We collected a total of 2,734 invertebrates representing 24 taxa in 11 families. The most diverse invertebrate family was Xanthidae (six species) followed by Palaemonidae (five species). We used ordination techniques to examine variation in species relative abundance among habitats, seasons, and sampling areas, and to identify environmental gradients correlated with species relative abundances. Our resulted indicated that oyster provided a similarly complex and important function as the adjacent VME. We documented three basic trends related to the importance of oyster and VME habitats: 1) Oyster and VME provide habitat for significantly more species relative to NVB, 2) Oyster and VME provide habitat for rare species, and 3) Several species collected across multiple habitats occurred at higher abundances in oyster or VME habitat. We also found that salinity, temperature, and depth were associated with seasonal and spatial shifts in nekton communities. Lastly, we found that the relative location of the two marsh complexes we studied within the context of the whole estuary may also explain some of the temporal and spatial differences in communities. We conclude that oyster habitat supported a temporally diverse and spatially distinct nekton community and deserves further attention in research and estuarine conservation efforts.     

Metal tissue levels in Steller sea lion (Eumetopias jubatus) pups

The endangered Western population of the Steller sea lion declined for three decades for uncertain reasons. We present baseline data of metal concentrations in pups as a first step towards investigating the potential threat of developmental exposures to contaminants. Seven metals were investigated: arsenic, cadmium, silver, aluminum, mercury, lead and vanadium. Vanadium was detected in only a single blubber sample. Mercury appears to be the most toxicologically significant metal with concentrations in the liver well above the current action level for mercury in fish. The concentrations of aluminum, arsenic, silver, cadmium and lead were present in one-fourth to two-thirds of all samples and were at either comparable or below concentrations previously reported. Neither gender nor region had a significant effect on metal burdens. Future work should consider metal concentrations in juveniles and adults and toxicological studies need to be performed to begin to assess the toxicity of these metals.     

Some recent studies in Sweden on the present climatic fluctuation

Summary This report deals with two different investigations on the present development of climate in Sweden. The first one gives a presentation of the fluctuations of temperature in various parts of Sweden since the beginning of records and including data from the last years. Special emphasize is placed on the discussion of what has happened to the winter and summer temperature since 1940, the year when many earlier studies of the climatic fluctuation end up. It is found that the winter temperature has dropped considerably since the 30-ies, as a matter of fact the 10-year overlapping means of mid-winter temperature in all Sweden shows lower values after 1940 than it has ever done since the beginning of the 19th century. This fact may suggest that the recent drop indicates an end of the warming up period in northern latitudes. It is strongly emphasized, however, that no definite conclusions should be drawn until longer records are available and comparisons are made between the 10-years overlapping mean curves and 30-years curves which show so far very little change in the last years. As regards the summer temperature there is a definite drop also as regards the northern parts of the country, but for the southern parts no definite change is found so far. Spring shows small fluctuations in recent years and autumn still is definitely warming up.The second part of the report deals with changes in the ice conditions along the Swedish coasts since the turn of the century or as long as reliable records are available. The considerable warming up is indicated very clearly by a shortening of the ice season up to around 1940. Later the development is more undefinite as in the case of temperature and even here are indications of a lengthening again of the season. There is a close relation between the time of ice break and the thickness of ice being indicated by highly significant correlation coefficients. The correlation between air temperature and time of ice formation is also shown to be significant.

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Zusammenfassung Zum Zwecke der Untersuchung der gegenwärtigen Klimaschwankung in Schweden werden zunächst die Temperaturschwankungen in verschiedenen Teilen Schwedens vom Beginn der Beobachtungsperiode bis in die neueste Zeit diskutiert. Dabei werden die Winter- und die Sommertemperaturen seit 1940 erörtert, also seit der Zeit, wo die meisten früheren Untersuchungen über die Klimaschwankungen aufhören. Es ergibt sich dabei, daß die Wintertemperaturen sei den dreißiger Jahren beträchtlich gefallen sind, indem die zehnjährigen übergreifenden Mittel der Hochwintertemperaturen in ganz Schweden seit 1940 tiefere Werte zeigen als jemals seit Beginn des 19. Jahrhunderts. Man könnte daraus schließen, daß die Erwärmungsperiode in den nördlichen Breiten abgeschlossen ist; doch lassen sich endgültige Schlüsse darüber erst ziehen, wenn längere Reihen vorliegen und Vergleiche zwischen den zehnjährigen übergreifenden Mitteln und den 30jährigen Mitteln möglich sind, an denen sich einstweilen nur ganz geringe Änderungen erkennen lassen. Die Sommertemperaturen zeigen ein deutliches Fallen in den nördlichen Teilen Schwedens, während in Südschweden einstweilen keine eindeutigen Schwankungen sich finden lassen. Der Frühling zeigt in den letzten Jahren nur geringe Variationen, während der Herbst eindeutig wärmer wird.Im zweiten Teil werden die Schwankungen der Eisverhältnisse längs der schwedischen Küsten seit Anfang des Jahrhunderts oder seit Beginn der Beobachtungen untersucht. Die beträchtliche Erwärmung läßt sich deutlich an einer Verkürzung der Periode der Eisbedeckung bis gegen 1940 erkennen. Seither wird die Entwicklung weniger eindeutig als bei den Temperaturen, doch treten auch hier Anzeichen für eine Verlängerung der Eisperiode auf. Es besteht eine enge und durch stark signifikante Korrelationskoeffizienten gesicherte Beziehung zwischen dem Zeitpunkt des Eisbruches und der Eisdicke; auch die Korrelation zwischen der Lufttemperature und dem Zeitpunkt der Vereisung ist signifikant.

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Résumé Ce travail se rapporte à deux différentes recherches sur les présentes fluctuations du climat en Suède. La première expose les variations de la température dans différentes régions de la Suède, depuis le début des mesures jusqu'aux données de ces dernières années. On discute spécialement les particularités des températures de l'hiver et de l'été depuis 1940, année à laquelle prennent fin plusieurs études antérieures, relatives aux fluctuations du climat. Ainsi on a constaté une baisse considérable des températures hivernales depuis les années 1930 à 1940, et il est certain que les moyennes de recouvrement de 10 ans de la température hivernale sont après 1940 les plus basses qui aient été observées dans toute la Suède depuis le début du 19ème siècle. Cette récente baisse peut laisser supposer que la période de réchauffement est terminée dans les latitudes septentrionales. Cependant il est impossible d'arriver à une conclusion définitive avant d'être en possession de plus longues séries de mesures et avant que l'on puisse comparer les moyennes de recouvrement de 10 ans aux moyennes de 30 ans, lesquelles ne montrent jusqu'à présent que de très petits changements. Les températures estivales montrent également une nette baisse dans les régions nord du pays. Dans le sud en revanche on n'a pas encore remarqué de changement jusqu'ici. Au printemps seules de modestes variations ont eu lieu, tandis que l'automne devient toujours encore plus chaud.La seconde partie du travail étudie les changements dans la formation de la glace sur les côtes suédoises depuis le début du siècle ou depuis les premières observations utilisables. Le réchauffement considérable est clairement documenté par un raccourcissement de la saison des glaces jusqu'autour de 1940. Pendant les années suivantes le développement est moins défini que dans le cas de la température et pourtant ici aussi on constate que la saison des glaces s'allonge de nouveau. Entre la période de la débâcle de la glace et l'épaisseur de cette dernière il y a une relation très nette ainsi que le prouvent des coefficients de corrélation très significatifs. Il y a également une corrélation significative entre la température de l'air et la période de formation de la glace.

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With 8 figures.     

The Role of Zooplankton Grazing and Nutrient Loading in the Occurrence of Harmful Cyanobacterial Blooms in Florida Bay,USA

Florida Bay is Florida’s (USA) largest estuary and has experienced harmful picocyanobacteria blooms for nearly two decades. While nutrient loading is the most commonly cited cause of algal blooms in Florida Bay, the role of zooplankton grazing pressure in bloom occurrence has not been considered. For this study, the spatial and temporal dynamics of cyanobacteria blooms, the microbial food web, microzooplankton and mesozooplankton grazing rates of picoplankton, and the effects of nutrients on plankton groups in Florida Bay were quantified. During the study, cyanobacteria blooms (>3 × 10⁵ cells mL⁻¹) persisted in the eastern and central regions of Florida Bay for more than a year. Locations with elevated abundance of cyanobacteria hosted microzooplankton grazing rates on cyanobacteria that were significantly lower (p < 0.001) and less frequently detectable compared to sites without blooms. Consistent with this observation, cyanobacteria abundances were significantly correlated with ciliates and heterotrophic nanoflagellates at low cyanobacteria densities (p < 0.001) but were not correlated during bloom events. The experimental enrichment of mesozooplankton abundance during blooms yielded a significant decrease in the net growth rate of picoplankton but had the opposite effect when blooms were absent, suggesting that the cascading effect of mesozooplankton grazing on the microbial food web was also altered during blooms. While inorganic nutrient enrichment significantly increased the net growth rates of eukaryotic phytoplankton and heterotrophic bacteria, such nutrient loading had no effect on the net growth rates of cyanobacteria. Hence, this study demonstrates that low rates of zooplankton grazing and low rates of inorganic nutrient loading contribute to the persistence of cyanobacteria blooms in Florida Bay.     

Morphometric comparisons between automated and manual karst depression inventories in Apalachicola National Forest,Florida, and Mammoth Cave National Park,Kentucky, USA

Karst depression catalogs are critical to assessing the hydrology and geohazards of an area; yet, the delineation of these features within a landscape can be a difficult, time-consuming and subjective task. This study evaluates the efficacy of karst depression inventorying using an automated fill-difference method operating on high-resolution lidar-derived digital elevation models (DEMs). The resulting catalog is compared with existing karst depression inventories for two low-development areas of the USA, Mammoth Cave National Park (MACA) and Apalachicola National Forest (ANF), where karst depressions have been mapped previously using a manual closed-contour approach. The automated fill method captures 93 and 85 % of these previously mapped karst depressions at MACA and ANF, respectively. Field observations and topographic analysis suggest that the omitted features were likely misclassified within the existing catalogs. The automated routine returns 797 and 3377 additional topographic depressions, at MACA and ANF, respectively, which are not included in the existing catalogs. While the geology of ANF is mostly homogenous Quaternary deposits, the newly identified, typically smaller-scale depressions found within MACA tend to be disproportionally located in non-carbonate-dominated formations, where the development of karst may be restricted by geologic heterogeneity. Within both areas, the size distributions of the two inventories are statistically identical for features larger than ~10³ m² in area or ~3 m in depth. For individual depressions captured by both methods at MACA, the automated fill-difference routine tends to return a slightly larger estimate of depression size and aggregate small depressions into larger ones. Conversely, at ANF, some low-relief depressions may be disaggregated by the fill-difference technique, with a trend toward smaller estimated depression areas when the automated method is employed. The automated fill-difference method, operating on high-resolution lidar-derived DEMs, can reproduce and expand the existing inventories of karst depressions, while minimizing false detections that may be inherent within pre-existing catalogs.     

Letters to the editor

Species composition and biomass of plankton samples taken on transects across an upwelling plume off Farewell Spit in February 1981 are presented. Copepods were numerically dominant, particularly Oithona similis and Paracalanus indicus. Also abundant were large phytoplankters (Chaetoceros sp. and Trichodesmium sp.), crustacean faecal pellets, and euphausiid larvae. The distribution of zooplankton species suggests mixing of inshore waters and neritic populations with upwelled waters. These data are discussed with respect to an interpretation of the upwelling system as a northwards transport of zooplankton and its enhanced productivity into the South Taranaki Bight.