The Effect of Human Exclusion on the Population Structure of Key-Hole Limpets Fissurella crassa and F. limbata on the Coast of Central Chile

Abstract. We describe the basic ecology of two key-hole limpets, Fissurella crassa and Fissurella limbata , which are heavily harvested by coastal shellfishermen (mariscadores) at the rocky intertidal of central Chile. The ecological role of human predation on these species was assessed. Anthropic exclusion from a stretch of the rocky intertidal at Las Cruces (non-harvested area) for about two and a half years resulted in changes of the densities and size distributions of these fissurelid species as compared to populations in control zones (harvested area). Differential human predation generates, on key-hole limpets, responses of different intensities related to the accessibility of man to the mesohabitats (sheltered platforms, exposed platforms and vertical walls) and fringes of the intertidal (mid-low intertidal and Lessonia nigrescens fringe). Thus, size distributions and mean densities of both fissurelids differ widely between the harvested and non-harvested areas on both platform habitats but not on vertical walls. In the mid-low intertidal fringe, differences are greater than in the less accessible L. nigrescens intertidal fringe. Moreover, we discuss the way in which other species, directly harvested by mariscadores (i. e., the mollusc Concholepas concholepas) can affect the keyhole limpet populations of central Chile rocky shores. Finally, we highlight the ecological role of these limpets on the dynamics of intertidal ecosystems and how they can modify community landscape.     

Zur Toxizität von Butonat,Trichlorfon und Dichlorvos gegenüber Escherichia coli und Enterobacter aerogenes

Butonat, Trichlorfon und Dichlorvos sind für Escherichia coli und Enterobacter aerogenes erst in relativ hohen Konzentrationen akut toxisch. Eine negative Beeinflussung der Wachstunisrate tritt im Konzentrationsbereich ≧1000 mg 1⁻¹ (Butonat, Trichloifon) bzw. ≧250 mg 1⁻¹ (Dichlorvos) ein. Bis zu diesen Konzentrationsbereichen werden die Wirkstoffe durch die Bakterien inaktiviert bzw. metabolisiert. Die Bestimmung der Wachstunisrate erfolgt über den Sauerstoffverbrauch der Kultur im SAPROMAT AP 12. Die Wirkstoffkonzentrationen werden dünnschichtchromatographisch analysiert.     

Contamination of Farmstead Wells by Pesticides, Volatile Organics, and Inorganic Chemicals in Kansas

Concern about the public health consequences of possible contamination of farmstead wells led to a random statewide survey in Kansas. Results of the analyses showed that 8 percent of tested wells had detectable amounts of pesticides, 2 percent had detectable amounts of volatile organic chemicals, and 37 percent had some inorganic contaminant exceeding the maximum contaminant level (MCL). Nitrate was the most common source of inorganic contamination, exceeding the MCL in 28 percent of the wells. Selenium levels exceeded the MCL in 9 percent of the wells. A multiple regression model for nitrate-N was developed. The factors included the age of the well, land use around the well, and the distance to the closest possible source of organic contamination.     

Mobility of arsenic in West Bengal aquifers conducting low and high groundwater arsenic. Part I: Comparative hydrochemical and hydrogeological characteristics

The present study demonstrates the importance of hydrogeochemical characteristics (groundwater flow and recharge) of an aquifer in the release of As to groundwater. The study area (∼20 km²) is located in Chakdaha block, Nadia district, West Bengal, which hosts groundwaters of variable As content. The spatial distribution pattern of As is patchy with areas containing groundwater that is high in As (>200 μg L⁻¹) found in close vicinity to low As (<50 μg L⁻¹) groundwaters (within 100 m). The concentration of groundwater As is found to decrease with depth. In addition, the data shows that there is no conspicuous relationship between high groundwater As concentration and high groundwater abstraction, although the central cone of depression has enlarged over 2 a and is extending towards the SE of the study area. The river Hooghly, which forms the NW boundary of the study site, shows dual behaviour (effluent and influent during pre- and post-monsoon periods, respectively), complicating the site hydrogeology. The observed groundwater flow lines tend to be deflected away from the high As portion of the aquifer, indicating that groundwater movement is very sluggish in the As-rich area. This leads to a high residence time for this groundwater package, prolonging sediment–water interaction, and hence facilitating groundwater As release.     

Application of micro-computed X-ray tomography for improving the hole erosion test analysis on high plastic clay

Acta Geotechnica - The hole erosion test (HET) was developed to simulate piping erosion and to study the erosion parameters of cohesive soils. The erosion rate in the HET is evaluated by the...     

Cytogenetic and cytotoxic effects in gill cells of the blue mussel Mytilus spp. from different zones of the Baltic Sea

Frequency of micronuclei (MN) and other nuclear abnormalities (nuclear buds, bi-nucleated and fragmented-apoptotic cells) was analysed in gill cells of the blue mussel (Mytilus spp.) from selected coastal sites in the Baltic Sea--Kv?d?fj?rden (Sweden), Klaipeda-Būtinge zone (Lithuania), Gulf of Gdansk (Poland) and Wismar Bay (Germany). Samples were collected from 650 specimens during bi-annual sampling campaigns in 2001 and 2002. The lowest frequency of MN (0.37 MN/1000 cells) was found in blue mussels from the reference site (Kv?d?fj?rden). The highest MN values (up to 6.7 MN/1000 cells) were registered in blue mussels from the Gulf of Gdansk in autumn 2001 and 2002, and at Wismar Bay in spring 2001 (up to 5.06 MN/1000 cells). Gradients of MN incidences were observed when comparing the three studied locations in Wismar Bay, and at the Lithuanian coast before the crude oil spill in the Būtinge oil terminal. Moreover, significant seasonal and inter-location differences in the responses were documented (P<0.0001). Nuclear abnormalities were observed most frequently in blue mussels from the Gulf of Gdansk.     

Regime shifts in the marine environment: the scientific basis and political context

Regime shifts in the marine environment have recently received much attention. To date, however, few large-scale meta-analyses have been carried out due to insufficient data coverage and integration between sustained observational datasets because of diverse methodologies used in data collection, recording and archival. Here we review the available data on regime shifts globally, followed by a review of current and planned policies with relevance to regime shifts.We then focus on the North and Baltic Seas, providing examples of existing efforts for data integration in the MarBEF Network of Excellence. Existing gaps in data coverage are identified, and the added value from meta-analyses of multiple datasets demonstrated using examples from the MarBEF integrated data project LargeNet. We discuss whether these efforts are addressing current policy needs and close with recommendations for future integrated data networks to increase our ability to understand, identify and predict recent and future regime shifts.     

Enzymatische Bestimmung von Glucose,Fructose und Saccharose in Gewässern

Zusammenfassung Die Anwendung der vonBergmeyer mitgeteilten enzymatischen Bestimmung von Glucose, Fructose und Saccharose in Gew?ssern erfordert bei Zuckerkonzentrationen unter 50 μMol/l eine spezielle Vorbereitung des Analysengutes, die anhand eines Beispiels beschrieben wird. Reproduzierbarkeit und analytische Ausbeute der Methode werden angegeben. Es wird auf die M?glichkeit hingewiesen, die Methodik auch bei der Untersuchung geologischer Proben einzusetzen.

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Summary Enzymatic analysis of glucose, fructose and sucrose by the method given byBergmeyer requires a special procedure when these sugars are determined in natural waters at concentrations below 50 μMol/l. The modified method, its reproducibility and analytical yield are described. The possibility of applying this method also to geological samples is considered.

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Résumé Le méthode du dosage enzymatique de la glucose, la fructose et la saccharose, indiquée parBergmeyer, est modifiée pour les cas où ces sucres doivent être déterminés dans des eaux naturelles à des concentrations inférieures à 50 μMol/l. On examine la variation statistique et l'exploitation analytique de la méthode modifiée. Celle-ci pourrait également être utilisée pour l'analyse d'échantillons géologiques.

     

Differences in the effects of mercury on predator avoidance in two populations of the grass shrimp Palaemonetes pugio

Adult Palaemonetes pugio were collected from two tidal creek systems, Piles Creek (PC), a mercury polluted estuary, and Big Sheepshead Creek (BSC), a relatively pristine creek. Adult killifish (Fundulus heteroclitus), a natural predator of P. pugio, were obtained from BSC. For each test, ten treated (0·01 mg/liter mercuric chloride (HgCl), or 0·01 mg/liter methylmercuric chloride (MeHg)), or control shrimp here introduced into a tank containing three fish. The time between capture of the first and second BSC HgCl treated shrimp was significantly faster (P < 0·05), as was the time between the first and second capture (P < 0·05) of MeHg treated BSC shrimp when compared with their respective controls. In addition, significantly more (P < 0·025) BSC HgCl treated shrimp were captured after 120 min. No significant difference existed between control and HgCl treated PC shrimp; however, significantly more PC MeHg treated shrimp were captured after 60 (P < 0·05) min when compared with their respective controls. These data suggest that PC shrimp, subjected to mercury in their natural environment, are more tolerant to the sublethal effects of both HgCl and MeHg. These data also suggest that behavioral studies can be very sensitive assays for determining the effects of sublethal concentrations of toxicants on populations of organisms.