ISSN:0020-9309    

DOI:10.1002/iroh.19880730102

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractVariations in biomass and maximal biomasses observed are reviewed. Trophic conditions are considered to be the main factor affecting both nonpredatory and predatory benthos abundance. Competition and predation by invertebrates seem to adjust the abundance of nonpredatory benthos to trophic conditions; both of these processes are influenced by fish. Examples of the role of benthos in ecosystems are reviewed.

ISSN:0020-9309    

DOI:10.1002/iroh.19880730103

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractThis report on the freshwater pulmonate basommatophoranLatia neritoidesof the North Island of New Zealand is based on field and laboratory studies. It deals with aspects of the habitat, describes biological adaptations of organs and organ systems inLatia, reviews the chemical basis of bioluminescence in this species, discusses the possible roles of light production inLatia, and addresses zoogeographic and phylogenetic questions.

ISSN:0020-9309    

DOI:10.1002/iroh.19880730104

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractPolychaetous annelids from a soft bottom community (1–46 m) were sampled from the Gulf of Nicoya, Costa Rica. A total of 125 species was identified, 120 from a faunistic study throughout the gulf and 78 species from a time study at four stations. The number of species from the Gulf was not as high as in some temperate areas. Temporal differences were slight compared to station differences. Twenty dominant species indicated three descriptive patterns: 1) Species with a marked seasonal peak and stable densities thereafter; 2) Species with a moderate seasonal peak and stable densities thereafter; and 3) Species with no discernible seasonal peak. Although 10 polychaete feeding guilds were identified, species from six feeding guilds were the dominant groups. The effect of the rainy season on polychaete opportunism and feeding guilds was discusse

ISSN:0020-9309    

DOI:10.1002/iroh.19880730105

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractWhen usingin‐situmethods such as the use of spectrometers aboard a ship, aircraft or satellites to estimate suspended matter (especially phytoplankton concentrations) in waters it is necessary to know the corresponding correlations between the matter concerned and the spectral reflectanceR(Λ) or colour indicesR(Λi)/R(Λj).Therefore, ship‐borne experiments were carried out on mesotrophic and eutrophic waters. The following parameters were measured: reflectance at the wavelengths 450, 550, 670, 705 nm, Secchidisk transparency, chlorophyll‐aconcentration, fluorescence, extinction, and scattering.Significant correlations (0.92

ISSN:0020-9309    

DOI:10.1002/iroh.19880730106

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractPopulations ofA. aquaticuswere sampled quantitatively in 1979–82 at two localities in the river Suså which has a slope of<1 m km−1and large variations in macrophyte biomass, discharge and stream velocity. The latter two differed significantly between years.A. aquaticushad (1)−2 life cycles per year and summer and winter cohort production intervals of 85 and 290 days. Populations ofA. aquaticusvaried between 0 and 28,000 ind. m−2with an exponential increase in the spring and an exponential decrease in the autumn‐winter. TheA. aquaticusrate of decrease varied between 0.62 and 5.61 % d−1and increased with increasing rate of elimination of the macrophyte biomass Differences between the two localities were due to differences in physical heterogeneity. Production varied between 2.8 and 9.1 g DW m−2yr−1and between 12.9 and 55 g DW m−2yr−1at the two localities andP/Bratios were 7.4–9.9 yr−1. Physical limitations are thought to be most important for the populations ofA. aquaticusin the Suså, and the macrophyte biomass played an important role in modifying the physical environment. Differences between streams and lake

ISSN:0020-9309    

DOI:10.1002/iroh.19880730107

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

The species composition of black flies (Simuliidae, Diptera) in a lowland stream of Aller‐Leineregion (northern Germany, FRG) is analysed in the course of several years. Normally,Odagmia ornata(MG.) is the dominating species. For a short sharply defined periodBoophthora erythrocephalaDEGEERappeared in a great number. Possible reasons and related research on spatial stability of oviposition sites are presente

ISSN:0020-9309    

DOI:10.1002/iroh.19880730108

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractFour perennial streams in a completely forested area were investigated. The water cooled and warmed up during both the rainy and dry seasons. The chloride content of the water varied according to rainfall. Dissolved solids were relatively high (20 mgl−1) at the start of the rainy season due to leaching but they were diluted with increased volume of flow. Dissolved gases and BOD5varied according to discharge and total suspended solids content. All the other chemical species likewise were subject to seasonal variation

ISSN:0020-9309    

DOI:10.1002/iroh.19880730109

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

摘要:

AbstractMeteorological, physical and chemical parameters of Vellayani Lake, Kerala, India, have been analysed for twelve months (August 1980 to July 1981), the topography of the lake is described, and correlation coefficients were calculated between meteorological and hydrographical parameters. The results indicate that the lake can be converted into a productive aquafarm by means of slight manuring.

ISSN:0020-9309    

DOI:10.1002/iroh.19880730110

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19880730111

出版商:Akademie Verlag, Berlin    

年代:1988

数据来源: WILEY