Semiquantitative estimates of Al and other cations in the leaf tissues of some Al-accumulating species using electron probe microanalysis

Electron probe microanalysis of transverse sections was used to provide semiquantitative estimates of Al and other cations in the leaf tissues of some Al-accumulating plants of the cerrado vegetation of central Brazil. Concentrations of Al were generally higher than those of other cations in the phloem elements of these plants growing on dystrophic as well as fertile acid soils. When one of the Al-accumulating species,Vochysia thyrsoidea, was grown in a calcareous soil, the concentration of Al in the phloem elements of leaves was lower than that of Ca and K though the cotyledons showed higher concentrations of Al than those of other cations.     

Progress since the first international symposium: ‘Genetic aspects of plant mineral nutrition’, Beograd, 1982, and perspectives of future research

Summary The paper discusses the problems of genetic aspects of plant mineral nutrition in the light of the results presented at the First and Second Symposia on ‘Genetic Aspects of Plant Mineral Nutrition’ organized in Beograd in 1982 and Madison in 1985, respectively. On the basis of the results, future directions of research are discussed. The papers deal with the concentration and content of mineral nutrients in different genotypes, physiological and biochemical aspects of the genetic specificity of plant mineral nutrition, relations between plant genotypes and nitrogen fixing micro-organism strains, as well as with some related problems which have been investigated to a lesser extent. Particular attention is paid to papers and problems referring to genetic and breeding research work linked with genetic aspects of plant mineral nutrition as well as the possibilities of developing new cultivars requiring certain soil and mineral nutrition conditions for their cultivation.     

Effect of differential gastric evacuation and multispecies prey items on estimates of daily energy intake in juvenile chinook salmon

Synopsis The caloric density of stomach contents in juvenile chinook salmon,Oncorhynchus tshawytscha, was not affected by gastric evacuation, suggesting a constant caloric density of stomach contents during evacuation. Differences in the caloric density of prey consumed did affect caloric density of stomach contents over a 24-h period. Consumption of the amphipodCorophium sp. was associated with reduced caloric densities of stomach contents. During periods whenCorophium contributed more than 4% of the stomach contents, average caloric density declined from 5.56 to 5.33 kcal g^–1. Despite this difference, estimates of daily energy intake of juvenile chinook salmon were only 3%, greater when developed from the mean caloric density of stomach contents excludingCorophium.     

Plant contents and quality of makhana (Euryale ferox)

Summary As a part of integrated study of makhana, the mineral contents of the plant parts and the fruits of makhana (Euryale ferox) have been presented here. It has been observed that the fruits were not only rich in minerals but also in protein. The plant parts also contained high amounts of micronutrients. Its fruits are, therefore, a good supplement for minerals which are produced from otherwise agriculturally waste (water-logged) areas.     

Feeding habits of Japanese butterfyfishes (Chaetodontidae)

Synopsis Stomach content data from 32 species of Japanese butterflyfishes of the family Chaetodontidae were used to classify them into feeding groups and to determine their important food resources. Four major feeding groups were distinguished: (1) obligative coral feeders which prey exclusively or mostly on Scleractinian corals, (2) facultative coral feeders that take both corals and other benthic organisms, (3) noncoralline invertebrate feeders which consume benthic invertebrates other than corals, and (4) zooplankton feeders. Ten species representing 31% of the butterflyfishes belong to the first category. The second and third categories include 13 (41%) and 8 (25%) species, respectively. The fourth category is represented by only one species which picks individual zooplankters, especially calanoid copepods, in midwater above the reefs. Facultative coral feeders consumed varying quantities of scleractinians (from 2 to 74% of food volume), along with a variety of benthic organisms including algae, alcyonarians, sea anemones, sedentary polychaetes, sponges, hydroids, etc. Noncoralline invertebrate feeders, on the other hand, tend to have low diversified diets, predominated by one prey item such as sea anemones, zoanthideans, polychaetes, or colonial ascidians. These dietary data suggest that scleractinian corals are the most important food resource for the Japanese butterflyfishes, and next important are sea anemones, sedentary polychaetes, alcyonarians, and algae.     

Sexual and site differences in calcium consumption by the Malabar Giant Squirrel Ratufa indica

Summary The calcium ingestion of Malabar Giant Squirrels Ratufa indica (Sciuridae) was examined at two sites, Magod and Bhimashankar, in western India. In females at Magod a positive correlation was found between rates of calcium ingestion from food resources and the contribution of those resources to the daily diet. This relationship was true for all females at Magod irre-spective of their reproductive condition. This relationship was neither significant for males at the same site nor for both sexes at Bhimashankar. A differential requirement for calcium between the sexes and the occurrence of higher rates of calcium ingestion or the probable presence of more easily digestible calcium at Bhimashankar are postulated to explain the observed phenomenon. Mature leaves and bark appear to be reliable sources of calcium at these sites.     

Egg contents in relation to host-feeding in some parasitic hymenoptera

Using transmission electron microscopy, egg content is studied in 10 parasitoid species, which either feed on host hemolymph or do not. As expected, hydropic eggs were found to contain little yolk which is only lipoid. In host-feeding species, the yolk contains a great number of typical protein bodies whereas in species that do not host-feed and which produce large eggs, the yolk contain very different bodies.     

赤松林受虫害后生物学及光谱学特征的变化

 本文重点研究春季山东招远赤松林受赤松毛虫危害后,其针叶形态特征、叶绿素含量及光谱反射率特征的变化,结果表明：春季赤松受赤松毛虫啃食危害后,树势衰弱,生长不良,针叶颜色变化,褪绿甚至死亡,可分为五个等级;随受害程度的加重,叶绿素含量逐渐降低;赤松受损后,红界光谱曲线拐点“蓝移”,可用特征参量Rs、Ro、λp、λpr、λo、R550-680的值表征。     

Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north-eastern coast: Habitat use and resource partitioning

Understanding the ecological role of species with overlapping distributions is central to inform ecosystem management. Here we describe the diet, trophic level and habitat use of three sympatric stingrays, Hypanus guttatus, H. marianae and H. berthalutzae, through combined stomach content and stable isotope (δ¹³C and δ¹⁵N) analyses. Our integrated approach revealed that H. guttatus is a mesopredator that feeds on a diverse diet of benthic and epibenthic marine and estuarine organisms, principally bivalve molluscs, Alpheus shrimp and teleost fishes. Isotopic data supported movement of this species between marine and estuarine environments. H. berthalutzae is also a marine generalist feeder, but feeds primarily on teleost fishes and cephalopods, and consequently occupies a higher trophic level. In contrast, H. marianae is a mesopredator specialized on shrimps and polychaetas occurring only in the marine environment and occupying a low niche breadth. While niche overlap occurred, the three stingrays utilized the same prey resources at different rates and occupied distinct trophic niches, potentially limiting competition for resources and promoting coexistence. These combined data demonstrate that these three mesopredators perform different ecological roles in the ecosystems they occupy, limiting functional redundancy.