Mesoscale, finescale and microscale distribution of micro- and nanoplankton in the Irish Sea, with emphasis on ciliates and their prey

We examined the degree of mesoscale (km), finescale (m), and microscale (cm) patchiness of ciliates and their prey in waters of varying hydrographic conditions. Samples were taken throughout the water column, along a transect across the Irish Sea (54°N), at scales ranging from 0.15 to 10⁵ m. We examined physical, chemical, and biological characteristics. The eastern and western Irish Sea were stratified, with a pycnocline at ∼20 to 30 m. The central waters were mixed and had adjacent frontal regions. Euphotic depth was ∼20 to 35 m. Generally, the upper waters were nitrogen-limited, with elevated levels associated with frontal regions and deeper waters. Microphytoplankton exhibited fine-mesoscale patchiness: diatom numbers were low in stratified waters, with higher levels in mixed and frontal regions; dinoflagellates were abundant in subsurface waters near the fronts. Nanoflagellate numbers and biomass decreased with depth below the pycnocline, and exhibited microscale distribution in upper waters; these micropatches may provide increased food levels for ciliates. Microscale distribution of ciliates was rare and only occurred at mixed/frontal sites; finescale ciliate patches were a more prominent feature of the water column. These finescale patches can be composed of a variety of taxa but can also be virtually monospecific. Finescale patches may produce localised regions of high productivity that is available to fishes and copepods, but may also be a sink, as patches can be short-lived and thus unavailable to predators. Received: 28 September 1998 / Accepted: 26 January 1999     

Coexistence between People and Elephants in African Savannas

Abstract: The decline in the range and numbers of elephants as a result of expanding human activity in Africa is recognized as one of the continent's more serious conservation problems. Understanding the relationship between human settlement patterns and elephant abundance is fundamental to predicting the viability of elephant populations. The prevailing model of human-elephant interaction predicts a negative linear relationship between rising human density and declining elephant density at a coarse (national or subcontinental) scale. Using observed elephant densities and human population data, we tested this prediction in a study area of 15,000 km² in northwestern Zimbabwe. The results did not fit a linear model. Elephant and human coexistence occurs at various levels of human density, up to a threshold of human density beyond which elephant populations disappear. This threshold seems to be related to a particular stage in the process of agriculturally transformed land becoming spatially dominant over the natural woodland that constitutes elephant habitat. Within the contexts of conservation and sustainable development in African savannas, investigating spatial relationships between elephant and human abundance should be a priority topic for future research.     

Prenatal diagnosis of thalidomide syndrome

A case of thalidomide syndrome diagnosed by ultrasound in the 17th week of pregnancy is presented. The pregnant woman had leprosy and received adjuvant treatment with thalidomide. The affected fetus was exposed to the drug until the 35th day of pregnancy and presented absent external ears, upper limb phocomelia and absent tibiae and fibulae. No internal organ abnormalities were noticed at autopsy.     

Ecodesign methods focused on remanufacturing

Understanding the product's ‘end-of-life’ is important to reduce the environmental impact of the products' final disposal. When the initial stages of product development consider end-of-life aspects, which can be established by ecodesign (a proactive approach of environmental management that aims to reduce the total environmental impact of products), it becomes easier to close the loop of materials. The ‘end-of-life’ ecodesign methods generally include more than one ‘end-of-life’ strategy. Since product complexity varies substantially, some components, systems or sub-systems are easier to be recycled, reused or remanufactured than others. Remanufacture is an effective way to maintain products in a closed-loop, reducing both environmental impacts and costs of the manufacturing processes. This paper presents some ecodesign methods focused on the integration of different ‘end-of-life’ strategies, with special attention to remanufacturing, given its increasing importance in the international scenario to reduce the life cycle impacts of products.     

Influence of diatoms on copepod reproduction. III. Consequences of abnormal oocyte maturation on reproductive factors in <Emphasis Type="Italic">Calanus helgolandicus</Emphasis>

Observations of gonads and oocyte development stages (OS) have been achieved in Calanus helgolandicus females fed different algal diets and starved in filtered sea water under laboratory conditions during 8 days. The effects of 20 diets on egg production rates (EPR), hatching success (HS) and proportion of abnormal larvae (AL, development stages N1-2) were examined. With the control diet Prorocentrum minimum EPR and HS values were high, while AL was very low, coinciding with intact cell structures in oogonia (OO) and normal OS (OS1-OS4). With the other diets, oocyte maturation, EPR, HS and AL patterns were partially or totally impaired. Decrease of EPR coincided with the arrest of OS3 maturation and oocyte degradations, characterised by cell fragmentation, presence of apoptotic bodies in the OS3, degradation of cytoplasm in OS3 and OS4 and consequently the arrest of OS4 formation. These degradations were reversible when females were fed a favourable diet. Results reflect the presence of two distinct inhibitory mechanisms. Inhibition mechanism (1) impairs egg production. It was induced by starvation or by several species belonging to Bacillariophyceae (Chaetoceros calcitrans, Guinardia delicatula, Guinardia striata, Odontella regia, Rhizosolenia setigera, Stephanopyxis turris, Thalassiosira pseudonana) and mixed-diatom assemblages (collected in the field) and to the prymnesiophyte Pavlova lutherii. Remarkably other diatoms like Navicula sp., Nitzschia sp., Skeletonema costatum and Thalassiosira rotula did not induce mechanism (1) Inhibitory mechanism (2) affected exclusively HS and AL and was triggered by species independent of the production of polyunsaturated aldehydes (PUA), which are supposed to have adverse impacts on HS and larval development.     

Identification of the dimethylbenzyl mercapturic acid in urine of rats treated with 1,2,3-trimethylbenzene.

The structure was investigated of the mercapturic acid excreted in urine of rats after the i.p. administration of 1,2,3-trimethylbenzene. Of the two regioisomeric mercapturic acids, i.e. N-acetyl-S-(2,3-dimethylbenzyl)-L-cysteine and N-acetyl-S-(2,6-dimethyl-benzyl)-L-cysteine, only the former was isolated by preparative HPLC and identified, by comparison with an authentic specimen. The excretion rate of the mercapturate was estimated to be approximately 5% of dose, not a substantial metabolic route.