摘要:

AbstractOccurrence and distribution of stony corals (Milleporina and Scleractinia) in the Gulf of Cariaco were investigated quantitatively using skin‐diving methods. Unusual temperature conditions due to cold upwelling limit coral growth to a depth of 15 m. A clear vertical zonation of species was observed, with five zones, in order of increasing depth, dominated byPorites porites, Millepora complanata, Siderastrea siderea, Dichocoenia stokesi, andSolenastrea hyades.Twenty‐one species of scleractinians and three species of hydrocorals have so far been found in the gulf. Of the total area covered by corals, over 50% is inhabited bySiderastrea siderea, Milleporaspp., andPorites porites.A horizontal zonation of the littoral was established based on species composition and density of the coral co

ISSN:0020-9309    

DOI:10.1002/iroh.19800650302

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThe aim of the investigations was to identify the main process controlling the rather low phosphate concentration in the water of Lake Balaton. Three processes were taken into consideration: a) phosphate uptake by algae, b) coprecipitation with biogenic lime, and c) adsorption on suspended sediment particles. A plexiglass box open at the bottom was placed in the shallow water with its sides extending into the sediment. The water in the box was stirred. When phosphate alone was added to the water in the box, its concentration decreased very rapidly. On the other hand, if NaOCl was also added in order to kill algae and bacteria, the phosphate concentration remained constant. This proves the priority of life processes in phosphate removal. In the next experiment phosphate and EDTA‐Na2were added simultaneously to the water in the box. The complexing agent prevented biogenic lime formation but did not influence the rapid phosphorus removal. This fact indicates that the main process involved in phosphate control is direct uptake by algae. The same conclusion was obtained in laboratory experiments where labelled phosphate was added to the bottles containing Lake Balaton water. It was demonstrated by the photo‐oxidation technique that the phosphate removed from the water was incorporated into the organic particulate mat

ISSN:0020-9309    

DOI:10.1002/iroh.19800650303

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650304

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractBenthic collections taken during a 34 month period from Little Egg Inlet, New Jersey were dominated by haustoriid amphipods and collections from a nearshore ridge/swale formation were dominated by ampharetid and capitellid polychaetes. Polychaetes were most abundant at the swale station where density was 2.4 to 17.5 times higher than at other stations. Changes in species composition and density were influenced by increases in the silt/clay component of the sediment which was influenced by depth, bottom topography, and exposure to currents.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650306

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThe primary goal of this study was to assess the importance of food in regulating densities of zooplankton in 3 northern Canadian lakes, where algal availability was low compared to temperate zone water bodies. Collections were made every 2 weeks during the summer and monthly during the winter from April 1978 to April 1979. Since the lakes were similar in most respects, including nannoplankton density, net phytoplankton density, temperature, depth, oxygen concentration and phosphorus levels, the seasonal cycles of the main species(Keratella cochlearis, Kellicottia longispina, Polyarthra remata, Polyarthra vulgaris, Cyclopsspp.,Diaptomusspp.) were generally similar throughout the study area. Changes in the densities of herbivorous species were poorly correlated with fluctuations in nannoplankton and net plankton availability, implying that food did not limit development. Although predatory copepods, particularlyCyclopsspp., were abundant, they also had no measurable impact on the main species. It was therefore concluded that temperature controlled the seasonal cycles and the ultimate population size of most zooplankters.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650307

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThere is scant information about the chemical composition of the mud‐water interface in shallow, aerobic, eutrophic bodies of water. This study is concerned with the chemical and mineralogical composition of the mud‐water interface of the Lake Huleh preserve (Israel). The most important conclusion gleaned from this investigation is that elements preferentially sorbed by the mud from the mud‐water interface in shallow, aerobic aquatic systems such as the Huleh preserve do so by two methods: organic matter sorption (cadmium, bromine) and scavenger action of ferric hydroxide (cesium, beryllium, mercury, tin, titanium, zirconium, bismuth, vanadium, molybdenum and iodine) type complexes. Forty‐six elements were detected in the mud‐water interface; their behavior in this system is

ISSN:0020-9309    

DOI:10.1002/iroh.19800650308

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650309

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractA contrast between temperate and tropical Cladocera, Copepoda and Rotifera zooplankton fauna shows a markedly different size composition and species diversity. There are fewer species, and these are generally smaller in the tropics than in either the North or South Temperate Zones. Larger species of the generaDaphniaandSimocephalusare relatively rare in the tropics, while members ofEurycerusandSayciaare absent. Members of the families Holopedidae, Leptodoridae and Polyphemidae increase in abundance toward the temperate regions. Two small cyclopoid copepods are common in tropical zooplankton, while many of the common larger species of other regions are absent or very rare. The chief rotifer components areKeratella tropicaand species ofBrachionus.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650310

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractPictures of phytoplankton samples were analyzed as raster images by means of a television camera and a Robotron 4200 computer. A feature vector described the objects irrespective of their angle. Each of the five genera involved were identifiable by a characteristic point cluster in ap‐dimensional feature space. A learning method was used during development of the classification structure, and the quality of identification was increased incrementally to the greatest possible degree.Asterionella formosawas identified in all cases without error despite the relatively coarse scanning grid. Errors in the identification ofFragilaria crotonensiscan be reduced by improving the resolution (over 100 picture elements per colony

ISSN:0020-9309    

DOI:10.1002/iroh.19800650311

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650312

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY