Weighted mean depth of zooplankton measured during various cruises to the Baltic Sea

The Baltic Sea is the largest brackish water area of the world. On the basis of the data from 16 cruises, we show the seasonal and vertical distribution patterns of the appendicularians Fritillaria borealis, Oikopleura dioica and the cyclopoid copepod Oithona similis, in the highly stratified Bornholm Basin. These species live at least temporarily below the permanent halocline and use different life strategies to cope with the brackish environment. The cold-water species F. borealis is abundant in the upper layers of the water column before the thermocline develops. With the formation of the thermocline abundance decreases and the specimens outlast higher temperatures below the halocline. Distribution and strategy suggest that F. borealis might be a glacial relict species in the Baltic Sea. Although Oikopleura dioica is only abundant during summer, O. similis is present all year round. Both species have in common that their vertical distribution is restricted to the waters below the halocline, most likely due to their requirements of higher salinities. We argue that the observed strategies are determined by ecophysiological constraints and life history traits. These species share an omnivorous feeding behaviour and the capability to utilise a spectra of small particles as food. As phytoplankton concentration is negligible below the halocline, we suggest that these species feed on organic material and heterotrophic organisms that accumulate in the density gradient of the halocline. Therefore, the deep haline waters in the Baltic Sea represent a habitat providing shelter from predation and food supply for adapted species that allows them to gather sufficient resources and to maintain populations.

Mesozooplankton in Bornholm Basin, Baltic Sea

The seasonal vertical distribution of mesozooplankton was investigated in the Bornholm Basin in October 1988, July 1991 and April 1992 by means of horizontal tows using a small net with a mesh size of 47 micrometers. This study shows that the vertical distribution of multivoltine copepods is linked with ontogeny and may also change seasonally, even in shallow areas such as the Baltic. Trends between copepod species, stages and seasons were discovered. Secondly, the correlation was investigated between the vertical mesozooplankton distribution on the one hand and chlorophyll a concentration and the density of medusae and fish larvae on the other hand. In several cases the comparison of the shape of the profiles led to greater differentiation than the coefficient of correlation. The abundances found allowed only scant statements about non-copepod taxa.

C4-saturated bipartite graphs

Let H be a graph. A graph G is said to be H-free if it contains no subgraph isomorphic to H. A graph G is said to be an H-saturated subgraph of a graph K if G is an H-free subgraph of K with the property that for any edge e is an element of E(K)\E(G), G boolean OR {e} is not H-free. We present some general results on K-s,K-t-saturated subgraphs of the complete bipartite graph K-m,K-n and study the problem of finding, for all possible values of q, a C-4-saturated subgraph of K., having precisely q edges. (C) 2002 Elsevier Science B.V. All rights reserved.

Relat??rio da IV reuni??o do comit?? gestor do projeto apoio ao desenvolvimento do setor algodoeiro dos pa??ses do C4

O projeto ???Apoio ao Desenvolvimento do Setor Algodoeiro dos Pa??ses do Cotton-4??? objetiva aumentar a produtividade, gerar diversidade gen??tica e aprimorar a qualidade do algod??o cultivado em Benin, Burkina Faso, Chade e Mali, de forma a contribuir para o desenvolvimento e o fortalecimento econ??mico. A IV Reuni??o do Comit?? Gestor do Projeto teve como um de seus objetivos refletir sobre as pr??ticas de implementa????o das a????es previstas no documento do projeto Cotton-4, bem como registrar percep????es e opini??es das equipes dos pa??ses africanos, com o prop??sito de reunir os elementos cr??ticos essenciais para sua posterior avalia????o