摘要:

Abstract.Samples ofBlennius incognitusfrom three differently polluted locations on the Istrian west coast (Adriatic Sea, Yugoslavia) were collected in early July during the spawning season. The gut content was analyzed employing the occurrence and point (relative volumetric) method. This fish grazes the surface of the rocky substratum. Inhabiting small benthic animals are ingested together with algae and detritus. The diet depends on the composition and condition of the covering phytal and its inhabiting fauna. A decrease of available animal food seems to intensify grazing on the substrate. A sexual dimorphism in the feeding habit during the reproductive period exists. Females feed more on animals; males feed more on substrate and in cases also on eggs of their own species.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00087.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Planktonic and benthonic foraminifera live in the desert‐enclosed, hypersaline and oligotrophic Gulf of Aqaba and northernmost Red Sea near the edge of their ecological tolerance. Marked changes in foraminiferal abundance patterns in the past, resulting from hydrological shifts related to global climatic fluctuations, facilitate a high‐resolution ecostratigraphic subdivision of deep‐sea records covering the last 150,000 years. Of particular significance are the foraminiferal plankton/benthos ratios, the presence/absence pattern of such species asGlobigerinoides sacculifer, as well as the frequency variation ofGlobigerina bulloules‐falconensis, Buliminacea, Miiiolaceaand various “rotaliform” species. Paleoceanographic interpretation of the shifts in assemblage composition and of stable oxygen isotope data obtained on planktonic foraminifera and pteropods indicates that during glacial intervals ‐ because of global cooling, lowered sea‐level and reduced water exchange at the straits of Bab‐el‐Mandeb ‐ the temperature of the upper waters fell by about 4–6oC (to 15–17oC), salinity rose by about 10%o to more than 50%0while residence time of the water became longer and the input/output ratio of nutrients became higher. As a consequence, fertility of the photic zone was higher, the organic content of the sediments increased and oxygen levels in the deep basin became reduced. Thus, sea level‐oscillations and strait‐dynamics played a major role in the foraminifera

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00088.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Two new species of the sponge genusUlosawere found living in symbiosis with a chroococcacean cyanophyte (cyanobacterium) in shallow Caribbean coral reefs off Belize (Central America).Ulosa funicularisis a stringy green sponge (styles: 157 × 2.5 μm, mean dimensions);U. arenosais a thickly encrusting, shaggy, brownish‐greenish mottled species with sandy ectosome (styles: 175 × 3.6 μm). The endosymbiotic algae make up 50% of the cellular sponge tissue. The algal cells are light green, spherical, 5–9 μm in diameter, and divide by median constriction. Electron microscopy shows that cell walls are fully developed but that thylakoids are unusual for their inflated sacs, which are in communication with the nucleoplasmic regions. Although the pigment composition is typical for theCyanophyta, the phycobiliproteins occur in con

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00089.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Two species of cerithid prosobranchs live on a sand flat in Bermuda. At low tide during day lightBatillaria minimais found on the surface whereasCerithium lutosumremains buried in the sediment. This correlates with much higher lethal and coma temperatures, as well as much greater resistance to desiccation, of the former species. However, at other diurnal or tidal stages the two species co‐occur in the same layer of sand. Despite greater resistance to physical factors the population ofB. minimaseems to be declining since in 1980 juveniles of this species were rare on Tuckers Town Flat whereas the population ofC. lutosumwas thrivin

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00090.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Two species of cerithid prosobranchs,Baiillaria minimaandCerithium lutosum, live on a sand flat in Bermuda. The two species execute complex vertical migrations, but they respond differently to light intensity and to water level. This ensures that in the course of tidal and diurnal cycles their maxima of vertical distribution are sometimes in thesame, sometimes indifferentlayers of sediment. This leads to a partial separation of niches.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00091.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Zooplankton was sampled with emergence traps on aThalassiabed behind an insular reef at San Salvador. Bahamas. These traps tested the effect of sealing the trap to the substrate or allowing it to rest unsealed on the substrate. Total numbers of plankters collected did not differ between the two types of trap, but significantly more cyclopoid copepods were collected in unsealed traps and significantly more tanaids were found in sealed traps. Total densities in unsealed traps were inflated as much as 24–28%by contamination with holoplankton. Both trap designs, but particularly the sealed traps, collected animals that apparently crawled up the insides. A substantial number of animals, as many as 9–31% of those collected in sealed traps, may not be actually planktonic. Our results suggest that reefs produce fewer meroplankters per unit of substrate, and thus meroplankters contribute less to reef foodwebs than formerly thou

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00092.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY