摘要:

AbstractThe present study aims to contribute to the general knowledge of Lakes Naivasha and Nakuru, the latter lake strongly saline and alkaline. Results are presented concerning water chemistry, chlorophyllaconcentrations, phytoplankton, Zooplankton, bottom fauna and fish material obtained from these lakes. Algal photosynthetic rates were calculated by the oxygen method.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620101

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractSpectrophotometric and paper chromatographic analyses of chloroplast pigments in the phytoplankton have been made from early spring until the end of summer in three Dutch freshwater lakes with different trophic characteristics. Pigment ratios and carotenoid: chlorophyll‐aratios are inaccurate and insensitive pigment characteristics, and in the description of diversity of pigments there is no alternative to chromatographic analysis. The chromatographically purified chlorophyll‐afraction together with the occurrence of breakdown products of chlorophyll‐agive valuable information on the stage of growth of phytoplankton populations. The pigment fractions fucoxanthin, peridinin, lutein and/or chlorophyll‐b, and myxoxanthophyll can be used to indicate the contribution of the different major algal types to total phytoplankton community pigments. In this way chromatographic pigment analysis may be an important tool in the description of phytoplankton community structure, particularly when used against the background of results of microscopic phytoplankton a

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620102

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractCluster analytic techniques were employed to define significant ecological groups of benthic species sampled in 2237 0.5 m × 1 m quadrats on a submerged barrier reef located off the Barbados west coast. For measures of species cover, number of colonies, presence‐absence, and cover of dead skeletal material, Lance and Williams' flexible sorting procedure defined eight species groups. Only four of these groups could be interpreted with confidence.Resolution of species groups increased with increasing environmental severity and decreased with decreasing species abundance. Highly resolved groups under strong environmental limitation included anAgaricia lamarcki‐sponge‐antipatharian association on deep outer slopes and a distinctiveAcropora cervicornis‐Madracis mirabilis‐rubble association of ridge‐top positions. The next two groups, in order of resolution, differentiated under strong competitive interaction. Associations dominated bySiderastrea siderea‐Montastrea cavernosaandMontastrea annularis‐Porites astreoidesconsisted of large colony‐forming species as part of a larger complex “mixed” coral association. The other four groups consisted of rare but widely‐occurring species. Probable reasons for the low resolution of these groups including severe disturbance, random colonization, niche specialization, and methodological idiosyncracies, were discussed.The efficacy of clustering procedures was discussed in relation to objectivity and efficie

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620103

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThis, the second of two papers on the ecology of temporary streams, attempts a generalization of the unique features of these habitats. The fauna is shown to consist of three main groups: permanent stream species, facultative species and specialized species. The members of certain major taxonomic groups tend to oversummer as similar stages in their life cycles and the oversummering method used reflects the type of life cycle exhibited by a particular species. These variations in life cycle lead to faunal succession. The coexistence of closely related species is shown to be common in temporary aquatic habitats and, as far as the most abundant taxa are concerned, the species composition is very stable from year to year.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620104

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractOver a course of one year total oxygen consumption of sediment cores was determined for the period of one week in a laboratory flow‐through system. The cores were collected during different months of the year and at two localities. One of the areas of investigation, at about 1 m water depth near the beach, had a carbon demand of 160 g C/m2/year. The other one, at a water depth of 11 m–a very heterogeneous sediment with a large gravel fraction — had a carbon demand of 100 g C/m2/year. As additional parameters for characterization of the sediments and interpretation of the determined metabolic rates particulate organic carbon and nitrogen, ATP, chlorophyll and pheopigments, bacterial counts and fauna composition were used. Both areas can be described as non detritus‐accumulating se

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620105

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractPreliminary studies on production by phytoplankton and bacteria in three large mountain lakes in Alberta, Canada (two in Waterton Lakes National Park and one in Jasper National Park) were concluded mainly through the use of the14C technique. The main experiments were conducted in August, 1974, and some were repeated in August, 1975. Net primary production rates varied little from 1974 to 1975, even though there were drastic changes in the phytoplankton composition. Production in the largest lake (max. depth 135 m; mean phytoplankton production 206.5 mgC.m−2.d−1) was approximately twice that for each of the two smaller lakes (max. depths 19 and 27 m: average phytoplankton production 109 mgC.m−2.d−1). Bacterial production estimates averaged 3.8 times those for the phytoplankton production, after a proportionalety large error in the dark‐uptake technique was subtracted. High production rates in the largest lake are probably due to enrichment. Bacterial production rates are comparable to those in smaller oligotrophic lakes

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620106

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe Rotifers of two planktonic‐series during a year out of the Kainji‐Lake in the African state Nigeria are identified. They have a similarity to those of the European warm pools (Tümpel, Altwässer). Two new varieties are described:Asplanchna brightwellivar. andEuchlanis myersi cri

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620107

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractPlankton was studied seasonally and quantitatively in Long Pond, St. John's, Newfoundland. This pond receives both rural and urban runoff and is characterized by a high flushing rate. A comparison is made with Clarkes Pond, Hogans Pond and Bauline Long Pond. Long Pond phytoplankton was characterized by nannoplankton (particularly flagellated forms). The most important zooplankters wereBosmina coregoniandDaphnia catawba. Aspects of plankton ecology are discussed in relation to eutrophication and water renewal.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620108

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe incorporation of an organic chelating agent (E. D. T. A.) in water containing the benthic polychaeteSabella pavoniafor 16 hours causes an increase of 25% in primary production.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620109

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractEntire colonies ofStylophora pistillataandAcropora variabiliswere collected along a depth transect 100 m south of the Marine Biological Laboratory of Hebrew University Elat, Israel. The branch height ofAcropora variabilisdecreases significantly with respect to depth, and this species is equitably distributed from 5 to 30 m.Stylophora pistillatademonstrated no decrease in branch height with respect to depth and its distribution is limited to shallow water. The changes in morphology and distribution enhance the credibility of a suggestion made by Roos (1967) that corals common at all depths would show changes in morphology that minimized self‐shading.Stylophora pistillatademonstrated an increase in branch density with respect to depth. A hypothesis, based upon the occurrence ofLithophaga cumingianaand water turbulence, is presented to explain the increase in branch density with respect to depth ofStylophora pistillat

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620110

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY