摘要:

Abstract.Dissolved free amino acids (DFAA) were measured in sediment porewater and overlying sea water in seagrass beds ofPosidonia oceanicaandCymodocea nodosaat a water depth of 8–10 m in Corsica, France. In the sea water, DFAA concentrations from 0.5 to 1.9μM were found. Lowest concentrations occurred in the afternoon in surface water samples, while higher concentrations were measured in morning surface samples and in all bottom samples. The most abundant amino acids were serine, glycine, and alanine. In the sediment, the upper 4cm contained the highest concentrations of DFAA (177nmol cm‐3or 367 μM), while lower concentrations (<50nmol cm‐3or 104 μM) prevailed deeper in the sediment. Glycine, glutamic acid, alanine, and β‐alanine were the major components of the DFAA. The photosynthetic activity of the seagrasses influenced sediment porewater pools of DFAA. When aPosidoniabed was covered with a black polyethylene shield, the interstitial amino acids were reduced at a rate of 16nmol cm‐2h‐1(0‐10cm depth). Conversely, extended daylight (floodlight) increased the DFAA pool in sediment depths below 4 cm. Free amino acids were released to the overlying sea water from both seagrass sediment and individual shoots, the rates being highest in the dark. The present investigation indicates that a substantial portion of the N‐cycling of the seagrass sediment includ

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Adaptive strategies on the ecosystem level are demonstrated using the properties of systems (community biomass, trophic level energy transfer). Development of stabilizing storages versus rapid turnover and energy transfer through the grazing food chain versus detritus food chain are shown to be adaptive processes leading towards an optimal performance of the system. A model of incorporation and processing of information in ecosystems is proposed which contains the essential features of evolution. The persistence of “interspecific altruism” is discus

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.Eupolymnia nebulosa (Terebellidae)andHermodke carunculata (Amphinomidae)were compared with respect to rates of oxygen consumption in response to acute temperature and salinity variation.E. nebulosa, but notH. carunculata, demonstrated significant temperature sensitivity correlating with the former species' restriction to habitats that are temperature variation. In contrast,H. carunculataoccurs where such fluctuation is common. Oxygen uptake in both species was responsive to dilution of the medium whereas onlyH. carunculatademonstrated insensitivity to increased salinity under most temperature conditions.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00269.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract.The shell‐boring gastropodOcinebrina edwardsi(PAYR.) lives associated withMytilus galloprovincialisLMK on which it preys. Predation is preferentially directed towards small (<15 mm long) mussels. The predation rate (number of mussels eaten per gastropod per day) for medium sized mussels (16–25 mm long) during a year ranges from 0.03 to 0.11. The predation rate is directly influenced by the sea‐water temperature. Predation follows a seasonal cycle reaching a maximum in July and a minimum in January.O. edwardsidrills selectively the median anterior region of the mussel valve, close to the dorsal

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1981.tb00270.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY