摘要:

AbstractIncluded among the diversified aquatic fauna occurring in the water associated with bryophytic coverings of cloud forests and rain forests and with the bottom litter of such forests are two closely related species of chydorid Cladocera –Bryospilus repensgen. et sp. nov. known from Puerto Rico, Venezuela, and New Zealand, andBryospilus bifidusgen. et sp. nov. known only from New Zealand. Beyond the certainty that these species belong in the subfamily Aloninae because of the nature of their mandible articulation, the location of the minor headpores in a far lateral position, and the general pattern of setation on the trunk limbs, little more can be said. In several respects, most strikingly the lack of a compound eye and certain peculiarities of the mandible articulation,BryospilusresemblesMonospilusmore closely than any other chydorid, although this may have resulted from convergence. The species are quite unique in their reduction of setation on the antennae and trunk limb I. The animals cannot swim. Instead they crawl about slowly but effectively in the wet bryophytes and forest litter. They have been collected from as high as 3–5 m above the forest floor, presumably having got there by their own efforts. This habitat is suspected to be comparable in its continuity over time to the ancient lakes of the World and hence can be expected to harbor other “endemic” species

ISSN:0020-9309    

DOI:10.1002/iroh.19800650502

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650503

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractHydroides dianthus(Verrill), a serpulid polychaete which secretes calcareous tubes, provides microhabitats for a variety of benthic invertebrates in Delaware Bay. These microhabitats function as biologically generated refuges and physical heterogeneities for at least 54 species. Dominance was measured by the biological index value which yielded 12 taxa that comprised 90% by number of the serpulid assemblage. These taxa included seven polychaetes, two amphipods, Nematoda, Oligochaeta, and Harpacticoida. In addition to the refuges provided by the serpulids, it was concluded that this temperate serpulid assemblage was comparable in function but not scale to calcareous biogenic assemblages in lower latitudes.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650504

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of algal food supply, temperature, water depth and lake size on the composition of benthic invertebrate communities were determined during 1978 und 1979 in 5 lakes in the Canadian subarctic. The lakes varied widely in physical conditions and trophic level, with peak algal densities ranging from 40 to 2100 mg/m3during the summer and 10 to 750 mg/m3in the winter. The correlation coefficients between the size of the populations of herbivorous chironomids(Chironomus riparius, Ch. plumosus, Ch. decorus, Tanytarsus xanthus)and the density of algae during the winter were highly significant and positive. There were also positive, albeit weak, correlations with the summer growth of algae, temperature, depth and lake size. In addition, the seasonal appearances of fourth instar larvae in the sediments were positively correlated with peaks in the abundance of phytoplankton. In contrast, algal food supplies probably had little impact on the density of oligotrophic indicator species(Heterotrissocladius oliveri, H. changi, Protanypus ramosus, Pontoporeia affinis)and were replaced in importance by temperature and water depth. Variations in the densities of the main oligochaete species(Uncinais uncinata, Arcteonais lomondi, Limnodrilus claparedeianus)and mollusc species(Valvata sincera helicoidea)could not be related to any of the factors that were measured. The diversity of the communities was probably limited by low temperatures, whereas food supply, lake depth and lake size had little impact on the fauna.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650505

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650506

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThe author found quite a close negative relationship between commercial catches of predatory fishes and of German carp(Carassius auratus)in the lower Danube. He supposes that the main reason for the population explosion and subsequent expansion of German carp in the Danube River basin seems to be a shift in the balance of the fish community due to a reduction in the density of predatory species.

ISSN:0020-9309    

DOI:10.1002/iroh.19800650507

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19800650510

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractA Monte Carlo model for the growth of phytoplankton in a regenerative system has been constructed. This model assumes that nutrients are regenerated randomly in time and space at the scale which is important to the individual organisms. Under such a regime, organisms originally arrayed in a random fashion assume a patchy distribution within fifteen or twenty divisions, with some species becoming nonrandom in their distribution within five divisions. Other factors, physical or biological, may also induce or enhance patchiness, but normal regenerative processes in a nutrient‐limited system are sufficient in themselves to explain the phenomenon. Patchiness should be considered as the normal state for nonmotile organism

ISSN:0020-9309    

DOI:10.1002/iroh.19800650511

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractIntegrated phytoplankton samples from two stations in the northern waters of western Lake Erie were analyzed by the Utermöhl technique for the period from June, 1975 to September, 1976, with weekly sampling in the summer of 1975. No consistent differences were observed between the two stations. Two annual peaks were found: the first was a vernal pulse (1.4 to 4.8 g/m3) comprised primarily of diatoms (86.0–95.7% of total biomass; principal species wereTabellaria fenestrata(Lyngb.) Kg.,Stephanodiscus hantzschiiGrun., andFragilaria capucinaDesm.); the second peak (3.1 to 9.9 g/m3) was in late summer – early fall. This latter peak consisted of initially diatoms (Coscinodiscus rothiiEhr. Grun. andMelosira granulata(Ehr.) Ralfs being the chief components), later dominated by bluegreens (Aphanizomenon flos‐aquae(L.) Ralfs andChroococcus minutus(Keutz.) Naegeli), and finally diatoms (Coscinodiscus rothii, Stephanodiscusspp.,Fragilaria crotonensis(Edw.) Kitton, andMelosira granulata).The importance of phytoflagellates (25.5 to 93.4% of total biomass), especiallyGymnodiniumsp.,Cryptomonas erosaEhrb., andCryptomonas erosav.reflexaMarsson., in June – early July samples and the overwhelming dominance of diatoms during the remainder of the year are stressed. No patterns in biomass and composition could be observed in vertical phytoplankton profiles. The present study provides an important connecting link between past and future studies performed with the standard Utermöhl

ISSN:0020-9309    

DOI:10.1002/iroh.19800650512

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY

摘要:

AbstractThe paper describes the seasonal variation in the rate of phytoplankton primary production in Suraha Lake – a large shallow water body – in relation to certain physico‐chemical parameters and the abundance and composition of the phytoplankton over a period of two

ISSN:0020-9309    

DOI:10.1002/iroh.19800650513

出版商:Akademie Verlag, Berlin    

年代:1980

数据来源: WILEY