Environmental Biology (environmental + biology)

Distribution by Scientific Domains

Selected Abstracts

Voracious invader or benign feline?

A review of the environmental biology of European catfish Silurus glanis in its native, introduced ranges
Abstract A popular species for food and sport, the European catfish (Silurus glanis) is well-studied in its native range, but little studied in its introduced range. Silurus glanis is the largest-bodied freshwater fish of Europe and is historically known to take a wide range of food items including human remains. As a result of its piscivorous diet, S. glanis is assumed to be an invasive fish species presenting a risk to native species and ecosystems. To assess the potential risks of S. glanis introductions, published and ,grey' literature on the species' environmental biology (but not aquaculture) was extensively reviewed. Silurus glanis appears well adapted to, and sufficiently robust for, translocation and introduction outside its native range. A nest-guarding species, S. glanis is long-lived, rather sedentary and produces relatively fewer eggs per body mass than many fish species. It appears to establish relatively easily, although more so in warmer (i.e. Mediterranean) than in northern countries (e.g. Belgium, UK). Telemetry data suggest that dispersal is linked to flooding/spates and human translation of the species. Potential impacts in its introduced European range include disease transmission, hybridization (in Greece with native endemic Aristotle's catfish [Silurus aristotelis]), predation on native species and possibly the modification of food web structure in some regions. However, S. glanis has also been reported (France, Spain, Turkmenistan) to prey intensively on other non-native species and in its native Germany to be a poor biomanipulation tool for top-down predation of zooplanktivorous fishes. As such, S. glanis is unlikely to exert trophic pressure on native fishes except in circumstances where other human impacts are already in force. In summary, virtually all aspects of the environmental biology of introduced S. glanis require further study to determine the potential risks of its introduction to novel environments. [source]

Ontogenetic variability in external morphology of bighead goby Neogobius kessleri from the Middle Danube, Slovakia

V. Ková
Summary Over the last decade, four species of goby have invaded the Middle Danube area, and all of them have spread rapidly. In the early 1990s, bighead goby Neogobius kessleri appeared in the Middle Danube, where it now seems to thrive. Relatively little is known of the environmental biology and ontogeny of this species in its native and non-native ranges. In this paper, preliminary results on the external morphology of bighead goby from the Slovak stretch of the Danube are presented within an ontogenetic context. Patterns of relative growth with no apparent changes at small size suggest direct development in bighead goby, although not as profoundly direct as observed in round goby N. melanostomus. Differences in life history between these two closely related species may have important implications for their success in novel environments, favouring the latter in short term (several years) and the former in long term (decades and longer) perspective. [source]


J.A. Raven
Symbiosis is important in the cell and environmental biology of algae. Some examples involving the author and numerous collaborators include: 1) chloroplasts of eukaryotic algae arose from endosymbioses. Plastids are incapable of independent existence; most of the genes of the cyanobacterial photobiont have been lost, and the majority of the rest have been transferred to the nuclear genome. Some of the genes retained by the plastid are those whose transcription is controlled by environmental cues transduced by the organelle. The general trend is for organelle genes to be transferred to the nucleus, escaping plastid redox activities generating mutagenic free radicals; 2) symbioses involving potentially free-living photobionts include marine lichens and sponges with cyanobacterial symbionts. For the lichen, Lichina, inorganic carbon acquisition appears to involve inorganic carbon transport by the mycobiont, and for the sponge, Cymbastella, the flagellar activity of the sponge is probably important for inorganic carbon supply to the photobiont; 3) the Australasian fucalean, Notheia, is an obligate epiphyte on the fucaleans, Hormosira and Xiphophora; the four species involved all contain the hexitol, altritol. Notheia anomala is known to be phyletically-distant from the other five altritol-containing species. Can Notheia synthesize altritol, or is it obtained from the phorophyte?; 4) Sacoglossan gastropods retain kleptoplastids (not strictly symbionts) from ulvophycean (or rhodophycean) marine algae. Analyses of the natural abundance of stable carbon isotopes suggest significant contribution of kleptoplastid photosynthesis to the carbon and energy budget of the mollusks. [source]