The present study was conducted to obtain estimates of certain biological and economic indices of the trophic structure of the Omani landed fish catch, namely, the mean trophic level (MTL), the fishing-in-balance (FiB) index and the relative price index (RPI). The MTL generally decreased from 1995 to 2010, indicating a fishing-down of the marine trophic web. The FiB index increased, indicating ...

The exchange of trophic factors by motor neurons and muscle fibers maintains the neuromuscular junction. Neurotrophic factors (muscle-derived trophic factors acting on motor neurons) and myotrophic factors (motor neuron-derived trophic factors acting on muscle fibers) may play a role in the generation of secondary myotubes and the maturation of neuromuscular junctions during development. It has...

The mean trophic level of the species groups reported in Food and Agricultural Organization global fisheries statistics declined from 1950 to 1994. This reflects a gradual transition in landings from long-lived, high trophic level, piscivorous bottom fish toward short-lived, low trophic level invertebrates and planktivorous pelagic fish. This effect, also found to be occurring in inland fisheri...

Introduction Macrophytes are essential for maintaining the health of shallow lake ecosystems, however, driving and responsive relationship between ecological factors (such as seasonal changes nutrition, etc.) plant communities is not yet clear. Methods In this study, we conducted surveys macrophyte community composition in lakes with different nutrient states, aiming to understand incidence rel...

We analyze the joint effect of contaminants and nutrient loading on population dynamics of marine food chains by means of bifurcation analysis. Contaminant toxicity is assumed to alter mortality of some species with a sigmoidal dose-response relationship. A generic effect of pollutants is to delay transitions to complex dynamical states towards higher nutrient load values, but more counterintui...

Various animals produce inviable eggs or egg-like structures called trophic eggs, which are presumed to be an extended maternal investment for the offspring. However, there is little knowledge about the ecological or physiological constraints associated with their evolutionary origin. Trophic eggs of the seminivorous subsocial burrower bug (Canthophorus niveimarginatus) have some unique charact...

Divergence in habitat use among closely related species is a common characteristic of adaptive radiations. Large differences in the size structure of prey between habitats could strengthen disruptive selection on generalist predators and lead to a divergence in trophic position among species in an adaptive radiation. Using threespine stickleback (Gasterosteus aculeatus) in freshwater lakes as a...

Recent studies have shown that the survival of mammalian motoneurons in vitro is promoted by neurotrophins (NTs) and cAMP. There is also evidence that neurotrophins enhance transmitter release. We thus investigated whether these agents also promote synaptogenesis. Cultured Xenopus spinal cord neurons were treated with a mixture of BDNF, glia-derived neurotrophic factor, NT-3, and NT-4, in addit...

The consequences of biodiversity loss for ecosystem functioning and ecosystem services have aroused considerable interest during the past decade. Recent work has focused mainly on the impact of species diversity within single trophic levels, both experimentally and theoretically. Experiments have usually showed increased plant biomass and productivity with increasing plant diversity. Changes in...