Relevance of intracellular partitioning of metals in prey to differential metal bioaccumulation among populations of mummichogs (Fundulus heteroclitus)

Intracellular partitioning of trace metals is critical to metal tolerance in aquatic organisms and may also influence metal trophic transfer in ecosystems. In this study, we tested the relevance of metal (Cd, Cu, Pb, and Zn) intracellular partitioning in prey as an indicator of metal trophic availability to benthic forage fish, mummichogs (Fundulus heteroclitus), in chronically metal-polluted salt marshes in New York, USA. Two common prey of mummichogs in the study area, Palaemonetes pugio and Nereis acuminata, generally stored increasingly higher proportions of non-essential metals (particularly Pb) in insoluble (less trophically available) cellular components, as the whole body burdens increased. In contrast, intracellular partitioning of essential metals (Cu and Zn) in invertebrate prey varied relatively little among sites. Differential Cd and Pb intracellular partitioning patterns within P. pugio among sites were significantly associated with Cd and Pb whole body burdens in mummichogs, respectively (i.e., prey-driven bioreduction of metals), while bioaccumulation of Cu and Zn in mummichogs was similar among populations. The findings in this study suggest that metal intracellular partitioning within prey may be partially responsible for metal trophic availability to a predator in metal-polluted habitats, while there was also evidence that some predator-dependent processes may offset differential trophic availabilities from prey.     

A review of marine mammal,sea turtle and seabird bycatch in USA fisheries and the role of policy in shaping management

This paper reviews the available information (observer programs, estimates, statutes, regulations) for bycatch of marine mammals, sea turtles, and seabirds in fisheries of the United States. Goals of the review were to evaluate the state of knowledge of bycatch and the role of existing protective legislation in shaping bycatch management for different taxa. Pressing issues are identified, as well as knowledge gaps and policy limitations that hinder multi-species bycatch reduction. The USA has made important progress toward reducing bycatch in its fisheries, but the efficacy of its management has been limited somewhat by a focus on taxon- and fishery-specific regulation and the lack of consistent mandate across taxa for taking a cumulative perspective on bycatch. Applying consistent criteria across taxa for setting bycatch limits (e.g., extending the approach used for marine mammals to sea turtles and seabirds) would be the first step in a multi-species approach to bycatch reduction. A population-based multi-species multi-gear approach to bycatch would help identify priority areas where resources are needed most and can be used most effectively.     

Sediment transport,biotic modifications and selection of grain size in a surface deposit-feeder

Deposit-feeders often select for particles on the basis of grain size. The available pool of particles at the sediment surface may be modified both by deposit-feeder activity and by sediment transport, but the effects of these alterations on deposit-feeder diet composition have received little attention. In laboratory experiments the spionid polychaeteParaprionospio pinnata altered the grain-size composition in its foraging area, and these alterations were reflected in grain-size changes in the diet. After simulated transport of fine-grain sediments,P. pinnata diets also changed in grain-size composition. Field data were collected from 9 m depth in the lower Chesapeake Bay. A video camera, deployed near the bottom, identified times of sediment transport over a 6-h Period;P. pinnata were collected concurrently for gut analysis. Consistent with predictions from the laboratory experiments,P. pinnata ingested primarily small-grain sizes. During periods of no sediment transport this feeding pattern reduced the relative availability of small particles; larger sediments were incorporated into the diet. Sediment transport may resupply the foraging area with fine-grain particles which are then incorporated into the diet. On these small spatial and time scales, deposit-feeder activity may affect the availability of food resources.     

Dispersion of surface plumes in the Southern North Sea

Summary Continuous releases of fluorescent dye were made in the southern North Sea and the power law dependence of the plume width, represented by _y , against the diffusion time determined. The spreading was non-Fickian and could be represented in the form _y ² =B ² t whereB was a diffusion velocity of magnitude 1.4×10^–2 m/s. Such spreading was reproduced in both particle tracking and finite difference plume models by allowing the horizontal diffusivity,K _H, to depend linearly on diffusion time. The weakness of this method is that it is not clear how the diffusion parameters can be extrapolated to weather conditions that are different to those prevailing at the time of the experiments. However, comparable spreading rates were obtained by combining a Fickian diffusion model with an advective field that represented the near-surface current shears due to wind and waves. The resulting shear diffusion effect produced realistic simulation of the observed dispersion rates. An advantage of this approach is that it enables predictions to be made over a range of weather conditions provided that the wind and wave shears can be accurately parameterized.

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Ausbreitung von Tracerwolken an der Oberfläche in der südlichen Nordsee

Zusammenfassung Fluoreszierender Farbstoff wurde in der südlichen Nordsee kontinuierlich freigesetzt und die Breite der Wolke, repräsentiert durch _y , in Abhägigkeit von der Ausbreitungszeit bestimmt. Die Ausbreitung folgte nicht dem Fickschen Ansatz und konnte in der Form _y ² =B ² t dargestellt werden, wobeiB eine Ausbreitungsgeschwindigkeit von der Größenordnung 1.4×10^–2 m/s darstellt. Eine derartige Ausbreitung wurde sowohl mit Modellen des Partikel-Tracking als auch mit Modellen der finiten Differenzen reproduziert, wobei die horizontale AusbreitungsgrößeK _H linear von der Diffusionszeit abhängig war. Die Schwäche dieser Methode ist, daß es nicht klar ist, wie die Diffusions-Parameter für andere Wetterbedingungen als zur Zeit des Experiments zu extrapolieren wären. Vergleichbare Ausbreitungsverhältnisse werden durch die Kombination eines Fickschen Diffusionsmodells mit einem advektiven Feld erreicht, welches die oberflächennahen durch Wind und Wellen verursachten Stromscherungen berücksichtigt. Der so resultierende Scher-Diffusions-Effekt erbrachte ein realistische Simulation der beobachteten Ausbreitung. Ein Vorteil dieses Vorgehens ist, daß es Vorhersagen über einen Bereich von Wetterbedingungen ermöglicht, vorausgesetzt, daß die durch Wind und Wellen verurschte Scherung zutreffend parameterisiert werden kann.

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La dispersion de la panache de surface dans la partie sud de la Mer du Nord

Résumé A partir de déversements continus de produits fluorescents effectués dans la partie sud de la Mer du Nord, on a pu déterminer l'expression de la largeur du panache _y , par son carré en fonction du temps de diffusion. La dispersion n'était pas du type Fickian et était représentée sous la forme _y ² =B ² t aB était une vitesse de diffusion de grandeur égale 1.4×10^–2 m/s. Une telle dispersion peut être reproduite par une modélisation du panache à la fois par suivi de particules et aux différences finies en admettant que le coefficient de diffusion horizontaleK _H dépendait linéairement du temps. L'inconvénient de cette méthode est qu'il n'est pas facile de savoir comment les paramètres de diffusion peuvent être extrapolés à des conditions météorologiques différentes de celles prévalant au moment des expériences. Quoi qu'il en soit, des taux de dispersion comparables ont été obtenus en combinant un modèle de diffusion Fickian avec un champ d'advection qui représentait les cisaillements de courant de surface dus au vent et aux vagues. L'effet de diffusion du cisaillement résultant produisit une simulation réaliste des taux de dispersion observés. Un avantage de cette approche est de rendre possible des prédictions réalisées à travers un éventail de conditions météorologiques à condition que les cisaillements liés au vent et aux vagues puissent être paramétrisés avec précision.

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Lacustrine sedimentation in a semiarid alpine setting: An example from Ladakh, northwestern Himalaya

The Lamayuru lacustrine strata in Ladakh typify many of the carbonate-rich Pleistocene alpine lakes found in the semiarid environment of the northern Himalaya. Created by a 200-m-thick landslide, the lake was in existence by at least 35,000 yr ago, and may have persisted until 500–1000 yr ago. Represented in the center by thin turbidites and laminated muds, the lacustrine sedimentation along the lake margins and low-relief deltas characteristically displays a marked contrast between (1) clastic lenses representing rapid, sporadic, matrix-poor debris flows and periglacial inputs from the alpine slopes and (2) abundant, diverse, shallow-water, biologically dominated carbonate strata, among which organism-rich, chalky beds and oncolithic and encrusted stem-rich strata predominate. Resemblances of the Lamayuru lacustrine strata and their setting to those of former lakes throughout areas north of the Greater Himalayan crest suggest that the alpine, semi-arid environment would favor diversified, spacially restricted carbonate sedimentation punctuated by occasional clastic influxes. Such a depositional regime contrasts strongly with that found immediately south of the Himalayan crest where more humid conditions promote a more continuous clastic influx into intramontane lakes.     

False drainage anomalies (?) in a granite area, Kvalöya in Troms, Norway — a case study

An anomalous area (100 km²) revealed by a previous regional overbank sediment sampling survey by the Geological Survey of Norway was followed-up for Ti, Nb, Y, Zr, La and Ce by drainage and lithogeochemical sampling and analyses. The drainage samples were anomalous in the same elements as in the overbank samples and contained similar concentrations. The lithogeochemical results did not indicate mineralization and showed only a small enhancement of Ti, Zr, La and Ce in mylonitic rocks.Mineralogical studies of the drainage samples revealed, apart from proportions of quartz and feldspars, that stream sediments and heavy mineral concentrates are similar in mineralogy, with epidote predomination and several vol% of fine-grained titanite and zircon. Drainage samples contained amounts of Nb, Y, and Zr up to ten times larger than average contents of rock samples. Enhanced light REE (La and Ce) and Nb reflect host minerals, titanite, and enhanced Y possibly zircon and/or allanite.Anomalies in both media do not relate to mineralization. The overbank samples and the drainage samples provide comparable geochemical data.     

On the significance of CO2 inclusions in plagioclase microphenocrysts in tholeiite from Moeraki,New Zealand

Liquid plus vapour inclusions of CO₂ are widespread in plagioclase microphenocrysts in small tholeiitic intrusions and tephra of the Moeraki and adjacent areas of northeast Otago, New Zealand. They imply the presence of immiscible CO₂ droplets in the magma at depths of about 7–14 km. Their presence within 5 μm of the edges of microphenocrysts as little as 35 μm thick and 118 μm long indicates minimal feldspar crystal growth during the final ascent and quenching of the magma. Delicate branching clusters of lath-like microphenocrysts escaped disruption during this ascent. Such CO₂ inclusions are a potential source of ‘excess argon’ perturbing K-Ar age determinations. Received March 24, 1993/Accepted September 10, 1993