Rapid shifting of foraging pattern by Yakushima macaques ( Macaca fuscata yakui ) in response to heavy fruiting of Myrica rubra

We describe short-term changes in foraging behavior by wild Yakushima macaques (Macaca fuscata yakui),which inhabit a warm-temperate broad—leaved forest on Yakushima Island (30°N, 131°E), Japan. Rapid changes of dietary composition, activity budget, and range use by the monkeys occurred from May to June, apparently associated with changes in the availability of the fruit of Myrica rubraBefore the fruit ripened, monkeys spent less time moving and more time feeding on many species of leaves, which accounted for 40% of feeding time. However, when M. rubrabegan to ripen, they fed intensively on the fruit, which accounted for three-fourths of feeding time,though the activity budget remained unaffected As fiuit of M. rubradecreased,the monkeys fed more on the fruit of other species and on insects, and spent more time moving at higher speeds. There marked shifts in foraging pattern occurred within only two months. In terms of moving cost and dietary quality,Yakushima macaques shifted their foraging pattern according to the availability of M. rubrafrom a “low-cost, low-yield” strategy to a “low-cost, high-yield” strategy, and then to a more costly strategy. The ability to make such rapid shifts in foraging pattern may allow the macaques to effectively use the highly variable food supply within their small range.     

A comparison of natural and human determinants of phytoplankton communities in the Kentucky River basin,USA

Physical, chemical, and biological characteristics of the Kentucky River and its tributaries were assessed for one year to compare effects of seasonal, spatial, and human environmental factors on phytoplankton. Phytoplankton cell densities were highest in the fall and summer and lowest in the winter. Cell densities averaged 1162 (± 289 SE) cells m1^–1. Cell densities were positively correlated to water temperature and negatively correlated to dissolved oxygen concentration and to factors associated with high-flow conditions (such as, suspended sediment concentrations). Chrysophytes, diatoms, and blue-green algae dominated winter, spring, and summer assemblages, respectively. Ordination analyses (DCCA) indicated that variation in taxonomic composition of assemblages was associated with stream size as well as season.Spatial variation in phytoplankton assemblages and effects of humans was investigated by sampling 55 sites in low flow conditions during August. Phytoplankton density increased with stream size. Assemblages shifted in composition from those dominated by benthic diatoms upstream to downstream communities dominated by blue-green algae and small flagellates. Human impacts were assumed to cause higher algal densities in stream basins with high proportions of agricultural or urban land use than in basins with forested/mined land use. While density and composition of phytoplankton were positively correlated to agricultural land use, they were poorly correlated to nutrient concentrations. Phytoplankton diversity changed with water quality: decreasing with nutrient enrichment and increasing with conditions that probably changed species composition or inhibited algal growth. Human impacts on phytoplankton in running water ecosystems were as great or greater than effects by natural seasonal and spatial factors. Our results indicated that phytoplankton could be useful indicators of water quality and ecosystem integrity in large river systems.     

Mangrove zooplankton of North Queensland,Australia

Food consumption, growth, fish length distributions,population sizes and habitat use of the salmonids intwo lakes in the Høylandet area were studied in1986–89. The allopatric brown trout (Salmotrutta L.) in the tarn Røyrtjønna (27 ha) fed mainlyon organisms at the lake surface , crustaceanplankton, Trichoptera and Chironomidae. Only 5% ofthe trout reached an age of 6 years and a length of25 cm. Sexual maturation started at age 3 and a lengthof 14 cm. Through mark – recapture technique thenumber of trout >10 cm was estimated to 115 ha^-1.Growth, fish length frequencies and sexualmaturation of the sympatric brown trout and Arcticcharr (Salvelinus alpinus (L.)) in LakeStorgrønningen (530 ha) were not much different. TheStorgrønningen charr fed chiefly on zooplankton whichby volume represented 33% for the trout. The foodconsumption of Storgrønningen trout was at maximum inJuly with 2.06 mg food (d.w.) per g live fish and forcharr in September with 1.26 mg food. The maximumsize-independent growth rate of trout was 5.2%day^-1 in late June, and for charr 4.1%day^-1 in late July. Seventy percent of theirseasonal growth took place before 15 August. The charrstayed mainly deeper than 3-4 m, at water temperatures<15 °C. Brown trout stayed mainly the littoralzone and in near surface water of the pelagic. Thenumber of pelagic charr was estimated hydroacusticallyto 50 ind. ha^-1. The charr spawn in thelake. Mean numbers of juvenile trout in the twolargest tributaries were 26 and 48 per 100 m².Their annual length increment was 2.8–3.4 cm. Noindication of acidification or other human inducedimpacts were found. The lakes and their tributariesrepresent complex aquatic systems, representative forpristine oligotrophic Norwegian lowland lakes.John W. Jensen died shortly after easter in 1996     

The ecology of ruffe,Gymnocephalus cernuus (Pisces: Percidae) introduced to Mildevatn,western Norway

Synopsis Diet, habitat use, diel and seasonal activity and a number of population parameters were studied on ruffe,Gymnocephalus cernuus, introduced to Mildevatn, western Norway. This lake is sited outside the natural range of the ruffe and has a lower fish diversity and a different fish species composition than within its native range. From June through September the ruffe was planktivorous and mainly caught at 4 to 6 m depth in the benthic zone. At other times of year ruffe was feeding on zoobenthos and caught deeper in the benthic zone. Ruffe was mainly day active. Zooplankton feeding during summer is the clearest difference compared to ruffe populations living within its natural range. Presence of large zooplankton organisms available for ruffe is suggested as the main reason for the difference found in food choice. The availability of large zooplankton is probably due to community structure caused by a predator and lack of interspecific competition for zooplankton in the deeper parts of the lake. Piscivorous brown trout.Salmo trutta, restrict the habitat of threespined stickleback,Gasterosteus aculeatus, to the zone of littoral vegetation, allowing high densities of larger zooplankton species likeBythotrephes longimanus to be present in the lake. Brown trout is present only in the upper light and well oxygenated parts of the lake, leaving a refuge for the ruffe, where they can feed on the rich zooplankton community.     

Spatial separation of fishes captured in passive gear in a turbid prairie lake

Synopsis Spatial separation of fishes in the littoral zone of a turbid prairie lake (Clear Lake, Iowa) was assessed with gill nets and fyke nets. Catch per unit of effort was used to determine differences among habitat types, sampling times within a 24 h period, and sampling months. Four of 10 species examined were significantly more numerous in one of the three habitats — nonvegetated, vegetated, or gravel-rock substrate. Black bullhead (Ictalurus melas) and bigmouth buffalo (Ictiobus cyprinellus) were most abundant in vegetated areas, yellow bass (Morone mississippiensis) in gravel-rock areas, and channel catfish (Ictalurus punctatus) in both non-vegetated and gravel-rock areas. Temporal patterns in habitat use were indicated for these four species, as well as yellow perch (Perca flavescens), white bass (Morone chrysops), common carp (Cyprinus carpio), walleye (Stizostedion vitreum vitreum), black crappie (Pomoxis nigromaculatus), white sucker (Catostomus commersoni). Journal Paper No. J-11039 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 2345. Financed by the U.S. Department of the Interior Office of Water Research and Technology and Iowa State University.     

Ecological release in feeding behaviour: the case of bluegills in Japan

The stomach contents were analyzed monthly for each year-class to elucidate the foraging pattern of bluegills in a small vegetated lake by the frequency occurrence and the points methods. Seasonal dietary changes of the year-classes were considered comparing the monthly fluctuations in abundance of major prey organisms. Though these bluegills are dietary generalists and opportunists like those in North America, their foraging pattern was characterized by a relatively clearer dietary shift during ontogeny and a wider food niche including piscivorous than those of bluegills with congeners in their home land. Therefore this finding provides evidence of the ecological release caused by the absence of congeners.     

Glandularia X hybrida (Verbenaceae), a new combination for a common horticultural plant

A new combination,Glandularia x hybrida, and a lectotype are proposed for the common Garden Vervain (Verbena xhybrida). The plant is of horticultural origin, but occurs widely in North America and Mexico as an adventive.     

Foliar δ13C within a temperate deciduous forest: spatial,temporal, and species sources of variation

Summary Foliar ¹³C-abundance (¹³C) was analyzed in the dominant trees of a temperate deciduous forest in east Tennessee (Walker Branch Watershed) to investigate the variation in foliar ¹³C as a function of time (within-year and between years), space (canopy height, watershed topography and habitat) and species (deciduous and coniferous taxa). Various hypotheses were tested by analyzing (i) samples collected from the field during the growing season and (ii) foliar tissues maintained in an archived collection. The ¹³C-value for leaves from the tops of trees was 2 to 3%. more positive than for leaves sampled at lower heights in the canopy. Quercus prinus leaves sampled just prior to autumn leaf fall had significantly more negative ¹³C-values than those sampled during midsummer. On the more xeric ridges, needles of Pinus spp. had more positive ¹³C-values than leaves from deciduous species. Foliar ¹³C-values differed significantly as a function of topography. Deciduous leaves from xeric sites (ridges and slopes) had more positive ¹³C-values than those from mesic (riparian and cove) environments. On the more xeric sites, foliar ¹³C was significantly more positive in 1988 (a dry year) relative to that in 1989 (a year with above-normal precipitation). In contrast, leaf ¹³C in trees from mesic valley bottoms did not differ significantly among years with disparate precipitation. Patterns in foliar ¹³C indicated a higher ratio of net CO₂ assimilation to transpiration (A/E) for trees in more xeric versus mesic habitats, and for trees in xeric habitats during years of drought versus years of normal precipitation. However, A/E (units of mmol CO₂ fixed/mol H₂O transpired) calculated on the basis of ¹³C-values for leaves from the more xeric sites was higher in a wet year (6.6±1.2) versus a dry year (3.4±0.4). This difference was attributed to higher transpiration (and therefore lower A/E) in the year with lower relative humidity and higher average daily temperature. The calculated A/E values for the forest in 1988–89, based on ¹³C, were within ±55% of estimates made over a 17 day period at this site in 1984 using micrometeorological methods.     

Carbon isotope discrimination at vegetative stage as an indicator of yield and water use efficiency of spring wheat (Triticum turgidum L. var. durum)

A field experiment was conducted to investigate if carbon isotope (¹³C) discrimination () measured at the vegetative stage of spring wheat (Triticum turgidum L. var. durum) is related with the yield and water use efficiency (WUE) at ripening. A line source sprinkler irrigation system exposed the wheat genotypes to different watering regimes, from rainfed to full irrigation and thereby increased the range in yield and WUE attainable in the four genotypes studied. The results indicated that values measured at the late stem elongation stage 60 days after planting (DAP), showed strong positive correlation with total dry matter yield (r=0.732^***), and a highly significant negative correlation with WUE (r=–0.755^***) measured at ripening 105 DAP. The data suggest that the imprints of measured at vegetative growth stage persists throughout the entire growth period, until maturity. Subject to confirmation from additional studies in other crops and locations, early measurements of may prove a useful tool for rapid and early screening of cultivars, for high yield and high WUE.     

大豆光合速率和气孔导度对水分胁迫的响应

土壤水分胁迫使两个供试大豆品种(系)光合速率和气孔导度降低,“鲁豆四号”降低的幅度大于小粒大豆品系“7605”。在相同的叶水势下,“7605”的光合速率和气孔导度均高于“鲁豆四号”,但“7605”气孔随水势下降而关闭的速率大于“鲁豆四号”。水分胁迫使叶片温度升高,“7605”比“鲁豆四号”升温较快,但在同一水分处理中,“鲁豆四号”的叶温高于“7605”。水分胁迫降低了大豆的水分利用效率,且“鲁豆四号”降低的速率大于“7605”。结果表明,“7605”对水分胁迫具有较好的适应能力。