摘要:

AbstractEighty topographic transects were made off the central Atlantic coast of Florida between Cape Canaveral and Palm Beach, November, 1973 to September, 1974, aboard the Research Vessel Gosnold. Profiles obtained with a precision depth recorder indicated the presence of continuous and discontinuous structures on the outer continental shelf and at the shelf‐slope break. Most conspicuous was a band of pinnacles, benches, mounds and troughs extending north from Fort Pierce to Cape Canaveral, Florida, and a massive mound occurring off St. Lucie Inlet. These occurred under the western edge of the Florida Current and along the edge of the continental shelf (about 80° W). From Fort Pierce southward to Palm Beach, these structures almost disappear.Dredgings in two selected areas of pronounced vertical profile, and preliminary visual and photographic observations made with the Johnson‐Sea‐Link I submersible, confirmed the existence of rich, sessile and motile invertebrate assemblages and fish populations associated with exposed limestone bedrock, talus, and the scleractinian coralOculina va

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620201

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe river Kleine Elster was studied as a typical example of slowly running waters of the lowlands with dense growths of submerged macrophytes. Photosynthetic oxigenation was found to be a function of biomass and light intensity as long as the biomass did not exceed 250 g (dry mass) per square meter. Crops going beyond this limit caused a substantial decrease in oxygen supply in the early morning hours. A biomass exceeding 250 g/m2also gave rise to critical situations in autumnal oxygen budget (dying of macrophytes), increased water level, retardation in flow and a drop in atmospheric oxigenation. Necessary management practices (cutting of weeds) were derived from the objective of stabilizing the oxygen balance.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620202

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractBirge‐Ekman box cores were used to sample the benthic invertebrate fauna near the Woods Hole, Massachusetts sewage outfall and a nearby control area. Community structure in terms of numbers and taxa fluctuated seasonally at both control site and at the outfall. The outfall fauna was dominated by small nematode worms, and the year‐round maintenance of a nematode‐dominated community may be a mechanism for utilization of the unpredictable, unnatural, excess organic material available around the outfall. Based on the small size of the invertebrates at the outfall compared to the other areas, it is suggested that the relationship between macrofaunal abundance and average individual size in an assemblage is a measurement of community structure which can be useful in assessing environmental distur

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620203

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe quantitative distribution of some important benthic invertebrates in a shallow inshore area of Kiel Bay (Western Baltic Sea) is described. This region is partly polluted by domestic sewage from the municipality of Kiel. Three groups of species are distinguished with reference to their densities and other population parameters in the different subareas: Progressive species of the 1st and 2nd order indicate a high and moderate to slight degree of pollution respectively by high population numbers. Regressive species are adverse indicators, absent or occurring in exceptionally low numbers in affected areas. In many cases the examination must be concentrated on sand bottom, because a series of species normally dwelling on aufwuchs build up dense populations in sand, if it is organically enriched.The polychaetesCapitella capitata, Nereis diversicolorandPolydora ligniare regarded as progressive species of the 1st order. The amphipodsCorophium insidiosumandGammarus salinus, the musselMytilus edulis, the polychaetePygospio elegans, the snailHydrobia ulvae, and some other invertebrates belong to the group of indicators for slight organic pollution. The main regressive species are the amphipodBathyporeia sarsiand the miteCopidognathus fabriciusi.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620204

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractLong Lake, Colorado, at an altitude of 3209 m, is oligotrophic and has an annual ice cover of 240 days. Greatest phytoplankton biomass (mostly μ‐algae) was attained in April and May under thick ice and snow. The Zooplankton was sparse;Cyclopswas most abundant in winter, but cladocerans and rotifers had no seasonal maxima. The lake had a total water replacement of 38.7 times per year. Heavy June runoff flushes cut more than 99% of the plankton. On an annual basis, about twice as much plankton biomass is lost through the outlet as comes in through the inlet. Total monthly organic seston sedimentation (fallout) rates for the whole lake ranged from 16.1 kg in October to 730.8 kg in June. Total annual seston production (balance) was 8.0 g organic matter or 4.24 g carbon/

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620205

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractPhotosynthetic rates as measured by the oxygen light and dark bottle method were highly correlated with estimates using the14C technique. The high O2/14C ratios found are explained by algal respiration and extracellular release which are included in photosynthetic measurements by the oxygen technique, while the14C method yields values close to net photosynthesis.Separation of net‐ and nannoplankton using a 50 μm plankton net for filtration was not comparable to distinctions made by microscopic examination. Separation of both by filtration caused a significant decrease in the photosynthetic activity of nannoplankton in 24‐hour incubations, but had no detectable effect after 4 hours of exposure.“Bottle effects” in 24‐hour measurements of photosynthesis were similar using both methods. Asymmetric photosynthetic time‐curves as well as vertical phytoplankton migrations were the main reasons for errors in estimates of daily photosynthetic rates from part‐day incubations which were extrapolated to

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620206

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe index of basin permanence, the ratio of basin volume to shoreline length, gives a morphometric index that reflects the littoral effect on basin volume. A large, deep lake would have a large permanence index (10,000 for Lake Baikal), while an extinct lake or a nearly extinct lake would have an index number of zero or a number approaching zero.

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620207

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractThe colonization of newly constructed fish‐ponds with phytoplankton is considered to be the result of inoculation by influents, airplankton and piscicultural measures. A considerable number of remarkable or new species have been observed, but bluegreen algae were extremely rare. The lack of a distinct seasonal succession in phytoplankton composition is attributed to the astatic character of the ponds. The following species are characteristic of the phytoplankton communities observed:Chlamydomonassp.,Chlorogonium elongatumv.plurivacuolatum, Cryptomonassp.,Cyclotella meneghiniana, C. pseudostelligera, Melosira varians, Pandorina moru

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620208

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY

摘要:

AbstractBaetis vermis, a major contributor to the biomass of the Breitenbach, shows a remarkable degree of fluctuation in its emergence, which — in the years under observation (1969–1975)—ranges from univoltine to trimodal patterns. It is postulated, that warm overwintering temperatures produce unimodal emergence whereas cold winter temperatures (esp. periods with less than 5° C) produce bimodal or trimodal emergence. The relations between egg‐hatching, larval growth and temperature are d

ISSN:0020-9309    

DOI:10.1002/iroh.1977.3510620209

出版商:Akademie Verlag, Berlin    

年代:1977

数据来源: WILEY