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Productive Area (productive + area)
Selected AbstractsPenguins as oceanographers unravel hidden mechanisms of marine productivityECOLOGY LETTERS, Issue 3 2002Jean-Benoît Charrassin ABSTRACT A recent concept for investigating marine ecosystems is to employ diving predators as cost-effective, autonomous samplers of environmental parameters (such as sea-temperature). Using king penguins during their foraging trips at sea, we obtained an unprecedented high resolution temperature map at depth off the Kerguelen Islands, Southern Ocean, a poorly sampled but productive area. We found clear evidence of a previously unknown subsurface tongue of cold water, flowing along the eastern shelf break. These new results provide a better understanding of regional water circulation and help explain the high primary productivity above the Kerguelen Plateau. [source] Differing body size between the autumn and the winter,spring cohorts of neon flying squid (Ommastrephes bartramii) related to the oceanographic regime in the North Pacific: a hypothesisFISHERIES OCEANOGRAPHY, Issue 5 2004Taro Ichii Abstract The neon flying squid (Ommastrephes bartramii), which is the target of an important North Pacific fishery, is comprised of an autumn and winter,spring cohort. During summer, there is a clear separation of mantle length (ML) between the autumn (ML range: 38,46 cm) and the winter,spring cohorts (ML range: 16,28 cm) despite their apparently contiguous hatching periods. We examined oceanic conditions associated with spawning/nursery and northward migration habitats of the two different-sized cohorts. The seasonal meridional movement of the sea surface temperature (SST) range at which spawning is thought to occur (21,25°C) indicates that the spawning ground occurs farther north during autumn (28,34°N) than winter,spring (20,28°N). The autumn spawning ground coincides with the Subtropical Frontal Zone (STFZ), characterized by enhanced productivity in winter because of its close proximity to the Transition Zone Chlorophyll Front (TZCF), which move south to the STFZ from the Subarctic Boundary. Hence this area is thought to become a food-rich nursery ground in winter. The winter,spring spawning ground, on the other hand, coincides with the Subtropical Domain, which is less productive throughout the year. Furthermore, as the TZCF and SST front migrate northward in spring and summer, the autumn cohort has the advantage of being in the SST front and productive area north of the chlorophyll front, whereas the winter,spring cohort remains to the south in a less productive area. Thus, the autumn cohort can utilize a food-rich habitat from winter through summer, which, we hypothesize, causes its members to grow larger than those in the winter,spring cohort in summer. [source] Ecological feedbacks and the evolution of resistanceJOURNAL OF ANIMAL ECOLOGY, Issue 6 2009Meghan A. Duffy Summary 1. ,The idea that parasites can affect host diversity is pervasive, and the possibility that parasites can increase host diversity is of particular interest. In this review, we focus on diversity in the resistance of hosts to their parasites, and on the different ways in which parasites can increase or decrease this resistance diversity. 2. ,Theoretically, parasites can exert many different types of selection on host populations, which each have consequences for host diversity. Specifically, theory predicts that parasites can exert negative frequency-dependent selection (NFDS) and disruptive selection on resistance, both of which increase host diversity, as well as directional selection and stabilizing selection on resistance, both of which decrease host diversity. 3. ,Despite these theoretical predictions, most biologists think of only NFDS or directional selection for increased resistance in response to parasitism. Here, we present empirical support for all of these types of selection occurring in natural populations. Interestingly, several recent studies demonstrate that there is spatiotemporal variation in the type of selection that occurs (and, therefore, in the effects of parasitism on host diversity). 4. ,A key question that remains, then, is: What determines the type of parasite-mediated selection that occurs? Theory demonstrates that the answer to this question lies, at least in part, with trade-offs associated with resistance. Specifically, the type of evolution that occurs depends critically on the strength and shape of these trade-offs. This, combined with empirical evidence for a strong effect of environment on the shape and strength of trade-offs, may explain the observed spatiotemporal variation in parasite-mediated selection. 5. ,We conclude that spatiotemporal variation in parasite-driven evolution is likely to be common, and that this variation may be driven by ecological factors. We suggest that the feedback between ecological and evolutionary dynamics in host,parasite interactions is likely to be a productive area of research. In particular, studies addressing the role of ecological factors (e.g. productivity and predation regimes) in driving the outcome of parasite-mediated selection on host populations are warranted. Such studies are necessary if we are to understand the mechanisms underlying the observed variation in the effects of parasites on host diversity. [source] Inorganic analysis of biological fluids using capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2008Andrei R. Timerbaev Abstract This review article focuses on recent advances of CE in determination of inorganic species in biological fluids and covers the years of dedicated research in the field since 2001 when a previous similar review was published [1]. The most productive area, in which CE has distinctively progressed over the review period, encompasses assaying major inorganic anions and cations in blood serum and urine. Other applications include assessing less abundant analytes, e. g., heavy metals or seleno-compounds, and less abundant body fluids (saliva, sweat, etc.). Special emphasis is placed on developments in CE methodology that comprised modifications of separation and detection hardware and using specific electrolyte modifiers to enhance the resolution of a CE system. Significant progress in the application of in-line preconcentration methods in order to move CE ahead closer to trace analyte levels is also brought into focus. A series of tables detailing highly developed CE procedures and the analytical figures of merit accomplished are included. Finally discussed are further strategies for the method's expansion in the practice of biomedical and clinical laboratories where CE could likely acquire the status of a benchmark analytical technique. [source] Predictions and tests of climate-based hypotheses of broad-scale variation in taxonomic richnessECOLOGY LETTERS, Issue 12 2004David J. Currie Abstract Broad-scale variation in taxonomic richness is strongly correlated with climate. Many mechanisms have been hypothesized to explain these patterns; however, testable predictions that would distinguish among them have rarely been derived. Here, we examine several prominent hypotheses for climate,richness relationships, deriving and testing predictions based on their hypothesized mechanisms. The ,energy,richness hypothesis' (also called the ,more individuals hypothesis') postulates that more productive areas have more individuals and therefore more species. More productive areas do often have more species, but extant data are not consistent with the expected causal relationship from energy to numbers of individuals to numbers of species. We reject the energy,richness hypothesis in its standard form and consider some proposed modifications. The ,physiological tolerance hypothesis' postulates that richness varies according to the tolerances of individual species for different sets of climatic conditions. This hypothesis predicts that more combinations of physiological parameters can survive under warm and wet than cold or dry conditions. Data are qualitatively consistent with this prediction, but are inconsistent with the prediction that species should fill climatically suitable areas. Finally, the ,speciation rate hypothesis' postulates that speciation rates should vary with climate, due either to faster evolutionary rates or stronger biotic interactions increasing the opportunity for evolutionary diversification in some regions. The biotic interactions mechanism also has the potential to amplify shallower, underlying gradients in richness. Tests of speciation rate hypotheses are few (to date), and their results are mixed. [source] Environmental ,loopholes' and fish population dynamics: comparative pattern recognition with focus on El Niño effects in the PacificFISHERIES OCEANOGRAPHY, Issue 4-5 2003Andrew Bakun Abstract A process of comparative pattern recognition is undertaken for the purpose of garnering insights into the mechanisms underlying some currently puzzling conundrums in fishery resource ecology. These include (a) out-of-phase oscillations between anchovies and sardines, (b) the remarkable fish productivity of the Peru,Humboldt marine ecosystem, (c) sardine population increases in the eastern Pacific during El Niños, (d) basin-wide synchronies in large-amplitude abundance variations, (e) characteristic spawning of large tuna species in poorly productive areas, (f) contrary trends in Pacific tropical tuna abundance during the 1970s and early 1980s. It is found that each of the items appears to become less enigmatic when the conceptual focus shifts from conventional trophodynamics to the idea that ,loopholes' in the fields of biological controls (i.e. of predators of early life stages), produced by poor ocean productivity or by disruptive environmental perturbations, may in fact lead to remarkable reproductive success. Implications include the following: (1) El Niño, rather than being an unmitigated disaster for Peruvian fisheries, may in the long run be a prime reason for the remarkable fishery productivity of the Peru,Humboldt large marine ecosystem. (2) Globally-teleconnected climatic trends or shifts might produce globally-coherent population expansions even when local environmental expressions may be quite different. (3) It may be unreasonable to expect any management methodologies to be able to keep the fish populations of highly climatically-perturbed systems such as the Peruvian LME always at stable high levels; an alternative approach, for example, might be to take optimal advantage of the transient opportunities afforded by the high fish productivity of such inherently erratic systems. [source] Prehistoric gold markers and environmental change: A two-age system for standing stones in western IrelandGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 2 2006K.R. Moore The Murrisk Peninsula in southwest County Mayo is a major target for gold exploration in Ireland. The most productive areas include the Cregganbaun Shear Zone and Cregganbaun Quartzite Belt on Croagh Patrick, both geologically related to Iapetus closure, and gold is concentrated in alluvial deposits of river systems draining these areas. A comparison of gold occurrences with the location of prehistoric stone monuments reveals that simple standing-stone monuments, though isolated from other monument types, correlate with alluvial gold. South of the Murrisk Peninsula in Connemara, isolated standing stones are associated with a wide range of mineral resources and with other monuments. Dating of the stones relative to blanket-bog expansion and coastal landform changes indicates that standing stones were raised as markers of gold placer deposits before a climatic deterioration at 1200 B.C. Late Bronze Age monuments with a ceremonial purpose are more complex and include stone alignments. © 2006 Wiley Periodicals, Inc. [source] THE IMPACTS OF MARINE RESERVES ON LIMITED-ENTRY FISHERIESNATURAL RESOURCE MODELING, Issue 3 2002JAMES N. SANCHIRICO ABSTRACT. We utilize a spatial bioeconomic model to investigate the impacts of creating reserves on limited-entry fisheries. We find that reserve creation can produce win-win situations where aggregate biomass and the common license (lease) price increase. These situations arise in biological systems where dispersal processes are prevalent and the fishery prior to reserve creation is operating at effort levels in a neighborhood of open-access levels. We also illustrate that using strictly biological criteria for siting reserves (e.g., setting aside the most biological productive areas) will likely induce the most vociferous objections from the fishing industry. In general, we find that the dispersal rate and the degree the patches are connected play a significant role on the net impacts on the fishing sector. [source] | |||||||||||||