Study on Energy of Castanopsis eyrei Community in Wuyi Mountains

Based on the measurement of biomass and productivity, the caloric value of plant samples, the standing crop of energy, net energy production and energy conversing efficiency of Castanopsis eyrei community were determined. There were some differences in caloric values among the fractions of C. eyrei community being highest in that of bark and lowest in that of the microroots. The standing crop of energy in C. eyrei community was 780584.1 kJ ·m-2, in which the standing crop of energy accumulated in the aboveground biomass was 678913.8 kJ · m-2, accounting 86. 98% of the total; that of underground was 101670.3 kJ · m-2, i. e. 13.02%. Net energy production was 26856.2 kJ · m-2 · a-1 for this community in 1992. To the photosynthetic active radiation on the stand, the energy conversing efficiency was 1. 296%.     

The ecology of eelgrass, Zostera marina (L.), fish communities. I. Structural analysis

Fish populations utilizing eelgrass, Zostera marina (L.), beds in two different estuarine areas near Beaufort, North Carolina were analysed and compared to determine aspects of their community structure. The fish community of the eelgrass beds was characterized by low diversity and high standing crops of biomass and energy, both of which showed seasonal variation. Wide temperature fluctuations related to the overall shallowness of the beds probably regulated the diversity of fishes utilizing the beds. This community was dominated by pinfish, Lagodon rhombiodes (L.), which comprised 45% and 67% of the fish biomass in the Phillips Island and Bogue Sound beds, respectively.Changes in total body caloric content were probably related to developmental stages and changes in diet. Adult fish often had significantly higher weight-specific caloric contents than juvenile fish. Monthly or seasonal variations in caloric content of the organic matter of pinfish had little influence on the caloric content within the various sizes of pinfish.There was a significant correlation between fish biomass, temperature, and Zostera biomass. Fish biomass was highest when temperature and grass biomass were at a maximum. In general, water depth over the beds had little effect on the standing crop of fish within the bed, but cooler waters which occurred at night, darkness, or both, had a large effect.     

Reproductive effort and efficiency in the female common goby, Pomatoschistus microps (Krøyer) (Teleostei: Gobioidei)

Reproductive effort and efficiency are terms which together help to describe the reproductive investment of spawning fish. In this paper they are applied to a small and abundant inshore fish, the common goby, Pomatoschistus microps (Kroyer), based on data collected from the wild, and by modelling likely breeding patterns. Wet calorimetry was used to determine the energy content offish tissue, and this allowed reproductive effort to be expressed as both an energy and a weight ratio of gonad to somatic body. The gonadosomatic index (GSI) calculated as an energy ratio was greater than that calculated as a dry "weight ratio". For ripe females the GSI (dry weight) at the onset of breeding was 67.5%. Theoretical and observed values of the maximum number of egg batches laid by a single female during a 16-week breeding season are 9-10, and this corresponds to a total caloric investment of almost 12 kJ. Estimates of the reproductive efficiency, using the dietary energy content during the breeding season, range from 28.2% to a maximum of 44.0%. These values are among the highest calculated for a fish species, and are in keeping with the long and intensive breeding strategy observed in the wild population.     

Production of submerged aquatic plant communities of Doodhadhari lake Raipur, (M.P. India)

The biomass of submerged aquatic plant communities was studied periodically during two annual growth periods. Najas minor contributed 78% to the total standing biomass. Ceratophyllum demersum, Hydrilla, Nelumbo nucifera, Trapa bispinosa and Potamogeton crispus contributed towards the rest of the biomass. The production was 0.64 g./m.²/day for the growing seasons of one year.     

围封对内蒙古锡林河流域羊草草原主要构成植物个体、枯落物及群落热值的影响

2010年8月,对中国科学院内蒙古草原生态系统定位站1979、1999和2004年围封的羊草样地进行取样,测定植物个体、枯落物及群落的热值,探讨不同围封时间对羊草草原主要构成植物、枯落物、群落热值及单位面积能量积累量的影响.结果表明:围封对羊草草原主要植物个体、枯落物、群落热值及单位面积能量积累量均具有显著影响.1979和1999年围封的羊草草原单位面积能量积累量显著高于2004年围封,2004年围封群落和枯落物的热值均显著高于1979和1999年围封,而1979和1999年之间无显著差异.在不同围封时间下,同种植物的热值差异显著,而不同种植物的热值则表现出一定差异;群落热值高低取决于构成植物,而单位面积能量积累量主要由草地的生物产量决定,二者的变化趋势均为短期内有一定波动,长期围封之后基本维持在一个较稳定的水平,最终达到生态能量平衡.     

武汉东湖大茨藻群落的研究

本文总结了1962—1964年和1972—1982年对东湖大茨藻群落的研究工作。研究的主要内容有:群落面积和生物量的逐年变化,物候相和种子发芽率,植物的光合作用和呼吸作用,以及植物群落对太阳能量的利用效率。最后提出了对大茨藻群落的改造问题。       

SUMMER FEEDING HABITS OF DALL'S PORPOISE, PHOCOENOIDES DALLI, IN THE SOUTHERN SEA OF OKHOTSK

Stomach contents were analyzed from 85 Dall's porpoises, Phocoenoides dalli , taken in the southern Sea of Okhotsk during the summer of 1988. Thirteen species of fish and five species of cephalopods were identified. Fishes comprising 9 families were predominant and made up 79.9% of the total number of prey, with an overall occurrence in the stomachs of 100%. Three families of cephalopods made up 20.1% of the total number of prey ingested, with an overall occurrence of 74%. The Japanese pilchard, Sardinops sagax melanostictus , was the primary prey and represented 72.0% of the total prey in 97.3% of the stomachs examined. The gonatid squid, Berryteuthis magister , ranked second and made up 16.9% of the total prey in 61.6% of the stomachs. Walleye pollock, Theragra chalcogramma , was the third most abundant prey item consumed and represented 6.0% of the total, with an occurrence of 53.4%. Composition of the sample by the calculated total mass and caloric intake supports the numeric findings on the relative importance of the three major prey species to the DaIl's porpoise diet. The Japanese pilchard was clearly dominant using these indices and constituted 65.4% of the total mass and 80.7% of the caloric intake. Berryteuthis magister made up 26.8% of the mass and 15.5% of the caloric intake. Walleye pollock contributed the least to the diet with 7.9% of the total mass and 3.8% of the caloric intake. Volumetric data indicate that porpoises are feeding heavily on Japanese pilchard throughout the daylight hours. Berryteuthis magister was probably fed upon in the late night or early morning hours. Occurrence of both Dall's porpoise and Japanese pilchard in the coastal waters of the southern Sea of Okhotsk is seasonal. The summer movements of Dall's porpoise into this region may be related to the seasonal migration and abundance of the Japanese pilchard.     

亚热带山地突脉青冈群落能量的研究

对突脉青冈（Ｃｙｃｌｏｂａｌａｎｏｐｓｉｓｅｌｅｖａｔｉｃｏｓｔａｔａ）群落植物体各组分的热值、群落能量现存量、能量年净固定量和太阳能转化效率的研究结果表明：该群落植物体各组分样品的干重热值具有一定差异,树皮热值最高,细根热值最低。突脉青同群落的能量现存量８５２０５８ｋＪｍ－２,其中地上部分７４１４１６ｋＪｍ－２,占总量的８７．０１％;地下部分１１０６４２ｋＪｍ－２,占１２．９９％。突脉青冈１９９６年群落能量净固定量为２８２７３ｋＪｍ－２,林地太阳光有效辐射能转化效率１．３５％。     

武汉东湖水生植物群落演替的研究

 本文根据1992～1993年调查结果并结合前人研究资料,讨论了东湖水生植物群落30多年来的动态变化及其与富营养化和渔业养殖等因素的关系,提出了东湖水生植物群落的演替系列是从微齿眼子菜阶段→微齿眼子菜+大茨藻+金鱼藻+狐尾藻阶段→微齿眼子菜消失阶段→大茨藻阶段→大茨藻+狐尾藻+苦草阶段。同时,还从物种生理生态、补偿和再生能力、生活史及生殖对策、种间关系等方面探讨了水生植物群落演替的物种替代机制及其演替模式,为湖泊水生植被恢复、人工调控和优化提供理论依据。     

PRODUCTIVITY AND PRODUCTION EFFICIENCY OF AN UPPER SONORAN DESERT EPHEMERAL COMMUNITY

During years with good winter rainfall, ephemeral plants can contribute considerably to primary production in the upper Sonoran Desert. This study was designed to compare ephemeral community productivity and production efficiency within the different microhabitats created by trees, shrubs and open spaces in a Sonoran Desert ecosystem. Ephemerals were periodically harvested in the different habitats and dried for biomass and caloric determinations. The caloric data were compared to total solar input into the different microhabitats in order to determine production efficiencies of each stand. Productivity rates were also determined for the total community for the sample period, winters of 1972-74. Both productivity and production efficiency were highest under the shade of Cercidium. The highest production efficiency occurring in the shaded sites was 5.03% which approaches the theoretical maximum photosynthetic efficiency level. The production efficiency of the entire ephemeral community for the whole growing season was only 0.17% during an optimal year, demonstrating the influence of the environment in the interspaces on productivity and solar conversion in the desert.     

Feeding behaviour of yearling and older hybrid grass carp

Hybrid grass carp resulting from the cross of a female grass carp, Ctenopharyngodon idella (Val.), and a male bighead carp, Hypophthalmichthys ( Aristichthys ) nobilis Rich., 12–18 months old ( c . 300 mm T.L.) were studied in a two-part experiment to determine feeding preference and total daily consumption fish^-1 on selected species of aquatic plants. Fish were maintained in circular pools with 6840·8 1 of water inside a temperature-controlled greenhouse. Preference tests were conducted at three temperature ranges; 25–28° C, 17–20° C and 12–15° C. Based on the time to complete consumption or the relative quantity consumed, the most preferred plant was Lemna gibba when in combination with six other species. Chara sp., Najas guadalupensis and Potamogeton peciinatus were readily consumed and considered to be of about equal preference. Ceratophyllum demersum and Myriophyllum brasiliense were least preferred. Hybrid grass carp generally consumed as much plant material species^-1 and in the same order of preference at the 12–15°C range as they did at 25–28° C. In the second part, mean daily consumption (g) fish^-1 at 25·7–31·0° C for five plant species tested separately was as follows: Chara sp. 369·8; Lemna gibba 178·2; Najas guadalupensis 172·6; Hydrilla verticillata 106·4 and Ceratophyllum demersum 8·8.     

The relationship between feeding preferences and consumption rates in grass carp and grass carp × bighead carp hybrids

The relationship between food preference hierarchy and consumption rate was examined for the grass carp, Ctenopharygodon idella , and its Fl hybrid (grass carp × bighead carp). Preferences of both types of fish were similar, although hybrids consumed vegetation at a much lower rate. For both, relative preference in feeding trials with mixed plant species was significantly correlated with consumption rate in monospecific feeding experiments. No correlations were found between preference and caloric content, protein content or relative water content. The hypothesis is proposed that preference hierarchies reflect relative handling times of different food types and that these fish maximize 'through-put' by preferentially consuming plant species which can be most rapidly ingested.     

Effect of salinity on chlorophyll and proline contents in three aquatic macrophytes

The role of proline in imparting tolerance to salinity was investigated in Hydrilla verticillata, Najas indica and Najas gramenia. The plants were exposed to different concentrations of NaCl and artificial sea water (SWS) separately. The chlorophyll (Chl) a/b ratio decreased significantly in all the three plant species in both NaCl and SWS treatments, comparatively more in former than the latter. NaCl resulted in drastic decrease in this ratio in salt sensitive H. verticillata and N. indica, but in somewhat lesser decrease in salt resistant N. gramenia. Proline content increased at both NaCl and SWS treatments, especially at the latter. However, in H. verticillata proline content at 1.5 and 2.5 % NaCl decreased. It was concluded that proline cannot be used as a biochemical marker of salt tolerance in aquatic plants, however, the decrease in Chl a/b ratio in response to NaCl may be used as an index of salt sensitivity in this ecological group of plants. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ecology and production of Salvinia natans Hoffim; in Kashmir

Summary Ecological problems arising as a result of rapid growth of S. natans Hoffim in some lakes of Kashmir have been studied. High viability of spores coupled with rapid vegetative propagation seem to be responsible for the spread of the weed. Lake channels protected from wind by a canopy of trees are the most favourable situations in which Salvinia produces a thick mat. Water in these channels is rich in nutrients. Oxygen poor layers of water beneath the mat are detrimental for insect and fish life. Besides, the changing light conditions have profound influence on the submerged vegetation. The most common associates of Salvinia are Hydrocharis dubia and Ceratophyllum demersum.Maximum plant biomass is recorded during August–September with higher efficiency at partially shaded sites. Correlation exists between caloric values and dry matter production and between caloric value and per cent organic carbon.Under laboratory conditions, water of a pH between 4.6–6.0, sodium chloride concentrations higher than 1 % and continuous submergence under water are harmful to the growth of the weed. Partial shady situations seem to be quite beneficial for the growth. Harvesting would probably be the most economical method of control.     

Najas marina in Israel: It is a halophyte or a glycophyte?

In Israel Najas marina L. grows mainly in fresh water habitats. The halophytic nature of a population from one such habitat was investigated. NaCl had a positive effect on the growth of Najas , with an optimal concentration of 37–55 μ M . Germination percentage was only slightly reduced by NaCl up to a concentration of 74 μ M . It is thus concluded that the populations of Najas in Israel retain their halophytic nature. In fresh water habitats, Najas grows under suboptimal NaCl concentrations.     

Biomass-dependent effects of common carp on water quality in shallow ponds

We examined the biomass-dependent effects of common carp (Cyprinus carpio) on water quality in 10 ponds at the Eagle Mountain Fish Hatchery, Fort Worth, Texas, USA. Ponds contained 0–465 kg ha⁻¹ of common carp. We measured limnological variables at weekly intervals for four weeks in early summer, after which ponds were drained and the biomass of fish and macrophytes was determined. Common carp biomass was significantly positively correlated with chlorophyll a, total phosphorus, total nitrogen, and Keratella spp. density and negatively correlated to bushy pondweed (Najas guadalupensis) biomass. In addition, we combined our data with data from comparable studies to develop more robust regression models that predict the biomass-dependent effects of common carp on water quality variables across a wide range of systems.     

Biofilter efficiency of <i>Eichhornia crassipes</i> in wastewater treatment of fish farming in Amazonia

Fish is a very important part of the human diet in Amazonia. Near the growing cities, fish populations and individual size have decreased over the past decades. Alternatives to traditional and industrial fishing arise, including fish farming. Strategies to minimize the impact of fish farms on the environment are needed to have a regular and healthy fish supply. This is to avoid a reduction of biodiversity, a depletion of natural resources, and/or the induction of significant changes in the structure and functioning of adjacent ecosystems. Very little research has been performed on management of effluents as to maintain the quality of water resources. The present study aimed at testing the efficiency of the Amazonian aquatic macrophyte Eichhornia crassipes as a biofilter for the treatment of effluents from fish farming. In three filtering treatments (50%, 75% and 100% plant cover) and a control (0%), physical and chemical properties of the water were measured and analyzed in a nursery with fish after passing the biofilter system, with a hydraulic retention time of 24 hours. The analyzed variables showed no significant differences (p>0.05) among the treatments with 50-100% cover, indicating that 50% cover would be enough for a good efficiency of the biofilter. All parameters were reduced after passage of the biofilter under the presence of E. crassipes: 73.7% for electrical conductivity, 15% for pH, 84.5% for turbidity, 86.8% for nitrite, 69% for total phosphorus, and 77.8% for orthophosphate. The concentrations of total nitrogen, nitrate and ammonium ions were not significantly changed (p>0.05). We conclude that E. crassipes is effective in improving the quality of effluents from fish farming, with less efficiency for nitrogen compounds. Our treatment system can be adopted by small and medium-sized farmers, aiming at a sustainable employment of the activity.     

Mechanisms affecting biomass and distribution of charophytes and <Emphasis Type="Italic">Najas marina</Emphasis> in Myall Lake,New South Wales,Australia

Two years of measurements are explored with a view to formulating an ecosystem model for Myall Lake. Stable physical characteristics, low catchment loads, low light attenuation, flat-bottomed hypsometry, and soft gyttja substrate allow stable charophyte biomass throughout the year in Myall Lake. Chara fibrosa dominates the total biomass and is abundant over the depth range 0.5–4 m. Nitella hyalina is found over the same depth range but has diminished biomass at depths greater than 2 m due to increased incidence of zero-biomass samples at depths greater than 1.5 m. Upper bounds for biomass densities were estimated for charophytes. Najas marina has great seasonal variability and meadows can have very high biomass in waters 1.5–2.7 m deep. High biomass of Najas marina is associated with low biomass of Nitella hyalina and may be a factor determining how the biomass of Nitella hyalina is distributed with respect to depth. Patchiness of Najas marina is particularly high. Temperature and light can support two growing seasons for Najas marina but mechanical disturbance is often high in spring and high biomass was only observed in late autumn during the present study. Less than 5% of the present-day production of submerged macrophytes would have been required to produce organic material of the gyttja over a 1,000-year period. The spatial distributions of gyttja and the dominant macrophytes are consistent with wind patterns. Down-lake limits on the distributions of charophytes and Najas marina are related to a gradient in the coefficient of light attenuation that is, in turn, related to proximity to the bulk of the catchment load.     

Trockengewicht und Kaloriengehalt sich entwickelnder Heringseier

Dry weight and caloric content of eggs from spring spawning western Baltic Sea herrings have been determined employing the bomb calorimetry technique. Water temperature throughout incubation was kept at 8.0°±0.2° C. Average dry weight and caloric content values of one pist fertilized egg are 0.170 mg (0.124 mg without chorion) and 0.748 cal (without chorion), respectively. The caloric content per egg decreases progressively during the incubation period (Fig. 2). The same holds for the dry substance of the egg (Fig. 1). Energy extraction efficiency related to dry weight is 67.8%, the efficiency related to dry organic substance 70.4%, and the caloric efficiency 63.7%.