Because mechanistic models of interspecific interactions are often complex, one should deliberately seek simple unifying principles that transcend system-specific details. Earlier work on resource competition has led to the "R* rule," which states a dominant competitor suppresses resources lower level than any other competing species. This rule describes outcome even ornate competition. Here we show analogous rules can characterize systems with predation. We first demonstrate, for two-prey,...

Many studies in population ecology and competition theory are based on models which the consumption rate of a resource is some function availability yield new consumers constantly proportional to amount consumed. For such models, best competitors at equilibrium have low requirements, nonequilibrium habitats high maximal growth rates. In this study, I abandon assumption constant allow rates be consumer's internal state with respect resource, as well external availability. Specifically, study...

Species-area relationships have been observed for virtually all major groups of macroorganisms that studied to date but not explored microscopic phytoplankton algae, which are the dominant producers in many freshwater and marine ecosystems. Our analyses data from 142 different natural ponds, lakes, oceans 239 experimental ecosystems reveal a strong species-area relationship with an exponent is invariant across span >15 orders magnitude spatial extent. A striking result derived small-scale...

Simple models representing nutrient-dependent growth of plant prey are used to study herbivores and edible "inedible" plants. Three types inedible plants considered: those that have no direct interaction with herbivores, interfere the ingestion but not themselves consumed, consumed provide nutritional benefit herbivores. A necessary condition for coexistence at equilibrium applies all plants, which requires be better competitors than in absence worse their presence. All predict compensatory...

Theoretical models of interspecific competition often assume equilibrium in population and resource dynamics, an assumption that is criticized. Departures from are hypothesized to reduce facilitate coexistence. When between two algae for one modeled using Monod equations, the species wins at does not usually win when resources supplied as periodic pulse, if second competitor has higher maximal growth rate. For model parameters typical nitrogen phosphorus limitation, this selection with high...

When local communities are assembled from a regional species pool, assembly rules state which of the this pool can coexist. I consider how herbivory and resource competition determine these rules, assuming that all plants limited by single herbivores specialists. Assembly for communities, consist parallel food chains, derived invasibility conditions. In particular, rule generalizes Tilman's R* is found. Equilibrium nutrient concentrations subcommunities in sequence any persistent community...

Mixed‐species batch cultures were used to measure kinetics of phosphorus‐dependent growth for 11 species freshwater algae. Results fitted the Monod model, and significant interspecific differences found. Indices competitive ability calculated from parameters suggest that Synedra radians, rumpens, Nitzschia acicularis, Chlamydomonas sp. are good competitors P, palea several nonsiliceous algae poor P. These indices largely consistent with outcomes in a companion experiment these other studies....

The growth rate, stationary cell concentration, and toxicity of Prymnesium parvum N. Carter were measured using a strain isolated from Texas inland waters. We used multifactor experimental approach with multiple regression analysis to determine the importance environmental factors, including temperature, light, salinity these algal measurements. Exponential rate was unimodal in relation salinity, irradiance, an estimated maximal 0.94 d −1 occurring at 27°C, 22 practical units (psu), 275 μmol...

ABSTRACT Allometric relations between physiological processes and cell volume surface area are combined with the variable‐internal‐stores model of growth to predict ability hypothetical phytoplankton compete for phosphorus at equilibrium. The analysis shows that spherical cells, smaller cells better competitors than large ones. For very elongated in shape, however, often small predicted be best compare favorably size shape species observed dominate phosphorus‐limited chemostats

Fish-killing Prymnesium parvum blooms have occurred in south-central USA for at least ∼30 years, with the last decade experiencing recurrent of large magnitude. In systems reported here, Lakes Possum Kingdom, Granbury and Whitney (Texas), P. were winter phenomena developing under conditions far from growth optimum. Bloom thresholds 10 × 106 cells L−1 observed as a function inflow salinity period 2000–2009. Lake only when 7-day accumulated inflows <10 m3 salinities >1.5 psu. For Whitney, <20...

Two species of green microalgae, Scenedesmus quadricauda var. longispina and chlorella sp., were grown together in cntinuous cultures under conditions phosphorus-limitation. This resource was supplied as a series discrete periodic pulse, preventing achievment strict equilibrium. mathematical models, based on the equations Monod Droop parameterized from earlier, single-species experiments. These models then tested for their ability to predict competitivedynamics these similar competition...

Variations in phytoplankton composition were observed over 2.7 years two warm temperate reservoirs north central Texas, Joe Pool Lake (JPL) and Eagle Mountain (EML), analysed relation to temperature, light, dissolved nutrients, seston nutrient ratios hydrological variables. The dominant variations both environmental variables seasonal strongly related the annual temperature cycle. Phytoplankton was annually periodic, with filamentous cyanobacteria, pennate diatoms chlorophytes summer, while...

The hypothesis that environmental variability promotes phytoplankton species diversity was investigated experimentally using phosphorus—limited continuous cultures. Variability introduced as a series of phosphorus pulses delivered at 8—d intervals. growth Synedra sp. and Fragilaria crotonensis examined in cultures natural phytoplankton, containing both no other monocultures. In inoculated with comparable densities species, competitively dominant to constatt varying cultures, but the rate...

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsSpecials 46:125-140 (2007) - doi:10.3354/ame046125 Effects of nutrient enrichment on Prymnesium parvum population dynamics and toxicity: results from field experiments, Lake Possum Kingdom, USA Daniel L. Roelke1,2,*, Reagan M. Errera1, Richard Kiesling3, Bryan W. Brooks4, James P. Grover5, Leslie Schwierzke1, Fabiola...

The haptophyte Prymnesium parvum forms harmful blooms toxic to fish in coastal and inland waters. Its growth relation niche factors is poorly characterized for the low salinities found waters which P. have occurred. specific rate of as a function temperature salinity was determined nutrient‐sufficient cultures with salinity. Additionally, phosphorus‐limited at temperatures or below 20°C. In cultures, decreasing from 4 g L −1 0.5 reduced . estimated optimal decreased about 27uC above 10 ,...

Information regarding air emissions from shale gas extraction and production is critically important given occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient samples residential within 61 m (200 feet) extraction/production determine whether a "fingerprint" chemicals can be associated with activity. Statistical analyses correlating fingerprint methane, equipment, processes performed. Ambient sampling was conducted at six...

A model for prey and predators is formulated in which three essential nutrients can limit growth of both populations. Prey take up dissolved nutrients, while ingest prey, assimilate a fraction ingested that depends on their current nutrient status, recycle the balance. Although individuals are modeled as identical within populations, amounts vary over time with reproductive rates increasing these amounts. Equilibria stability depend supply conditions. When increases, unusual results occur,...

Two microbial communities were grown in chemostats receiving a low supply of inorganic Phosphorus (P) (10 μM) and different supplies organic carbon (OC), ranging from 0 to 600 μM, either as glucose or mixture substrates. One community was natural assemblage lake plankton the other model composed cultured organisms. As ratio OC P increased, concentrations dissolved decreased abundances phototrophic algae decreased. Abundances bacteria phagotrophic organisms did not consistently change with...