Monitoring of abiotic compartments for trace metals: Difficulties,strategies and the use of surveys

The high variabilility in coastal water parameters allows no effective large scale monitoring exercise within acceptable logistic and economic means; however, in the ideal case monitoring of marine pollution should comprise biotic and abiotic compartments. Different regions, e.g. turbulent, polluted, turbid coastal areas, relative clear clean open sea and relatively undisturbed sediments require their specific approach, for which strategies are presented.Based on surveys from the Dutch Wadden Sea and North Sea, the dissolved and particulate water fractions and sediment are discussed in terms of possible objects for monitoring.     

Electric Signals in the Social Behavior of Sympatric Elephantfish (Mormyridae, Teleostei) from the Upper Zambezi River

 Electrocommunication in mormyrid fish from African freshwaters is a challenging research field in neuroethology (Turner et al. 1999). However, virtually nothing is known about electrocommunication within natural mormyrid populations involving sympatric, syntopic species. Here we report on the nocturnal activities and electrocommunication among three syntopic species in a spacious laboratory setting resembling the natural one. Petrocephalus catostoma, Cyphomyrus discorhynchus, and Hippopotamyrus sp. nov. differ characteristically in their behavior, such as in territorial defense, schooling, and joining members of other species during foraging. Comparing social encounters within and between species, the first evidence for interspecific electrocommunication among syntopic species was found. Received: 27 September 1999 / Accepted in revised form: 22 December 1999     

Resource users as land-sea links in coastal and marine socioecological systems

Coastal zones, which connect terrestrial and aquatic ecosystems, are among the most resource-rich regions globally and home to nearly 40% of the global human population. Because human land-based activities can alter natural processes in ways that affect adjacent aquatic ecosystems, land-sea interactions are increasingly recognized as critical to coastal conservation planning and governance. However, the complex socioeconomic dynamics inherent in coastal and marine socioecological systems (SESs) have received little consideration. Drawing on knowledge generalized from long-term studies in Caribbean Nicaragua, we devised a conceptual framework that clarifies the multiple ways socioeconomically driven behavior can link the land and sea. In addition to other ecosystem effects, the framework illustrates how feedbacks resulting from changes to aquatic resources can influence terrestrial resource management decisions and land uses. We assessed the framework by applying it to empirical studies from a variety of coastal SESs. The results suggest its broad applicability and highlighted the paucity of research that explicitly investigates the effects of human behavior on coastal SES dynamics. We encourage researchers and policy makers to consider direct, indirect, and bidirectional cross-ecosystem links that move beyond traditionally recognized land-to-sea processes.