—The index of biotic integrity (IBI) has become a widely used tool for assessing the condition of stream fish communities and the overall biological status of streams. Because the location of a stream in a drainage network can influence the species richness offish communities and because species richness is an important component of the IBI, we examined the influence of stream spatial location ...

It has been well established that the trophocytes, or nurse cells of heteropterous ovaries, contribute a variety of cytoplasmic components to the developing oocytes (Bonhag, 1958) . Hemipteran ovaries are of the telotrophic type in which the nurse cells are confined to the apical trophic-chamber of each ovariole and are connected to developing oocytes, during their early stages of differentiati...

Consumer trophic position 2 3 4 5 Im pa ct s on p rim ar y pr od uc tiv ity (p ro po rti on al c ha ng e) -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 40% consumption of lower trophic level a r t i c l e i n f o

IntraspeciWc diversity can inXuence the structure of associated communities, though whether litter-based and foliage-based arthropod communities respond to intraspeciWc diversity in similar ways remains unclear. In this study, we compared the eVects of host-plant genotype and genotypic diversity of the perennial plant, Solidago altissima, on the arthropod community associated with living plant ...

These impacts of fisheries have led, in the late 1990s, to a growing interest in "ecosystembased management" (see e.g. NRC, 1999). Moreover, though the full implications of such form of management continue to remain elusive, there is a growing understanding that ecosystembased management must consider and maintain the structuring role of large predators in marine food webs. The demonstration by...

Productivity, trophic structure, and energy flow in the steady-state ecosystems of Silver Springs, Florida W.M. Kemp a,∗, W.R. Boynton b a Horn Point Laboratory, Center for Environmental Science, University of Maryland System, Box 775, Cambridge, MD 21613, USA b Chesapeake Biological Laboratory, Center for Environmental Science, University of Maryland System, 1 Williams Street, Solomons, MD 206...

We tested whether standing autotrophic (unicellular algal) biomass is sensitive to variation in initial consumer (nondecomposer, heterotrophic protistan) diversity in experimental microbial microcosms. Our results showed a strong, negative relationship between autotrophic biomass and consumer species richness. Additional microcosm experiments showed that this relationship was due largely to the...

This contribution examines various flow measures based on analysis of 41 quantified models of trophic interactions in aquatic ecosystems. System productivity/biomass ratio is shown to relate to ecosystem maturity and to the degree of cycling in the systems. Distinct patterns or clusters are observed for different types of resource systems with respect to average path lengths and residence times...

Ecologists have hypothesized that the exponent of species-area power functions (z value) should increase with trophic level. The main explanation for this pattern has been that specialist predators require prior colonization of a patch by their prey, resulting in a compounding of the effects of area up trophic levels. We propose two novel explanations, neither of which assumes trophic coupling ...