摘要:

Abstract.The history of the study of hydroid ecology is briefly outlined, pointing out the major methodological innovations which have contributed to the development of ecological research in the last thirty years. The influence of the major ecological factors on hydroid ecology and biology is synthesized, taking into account: substratum, water movement, light, salinity, sedimentation, exposure to air, temperature, food availability and pollution. Besides affecting the species composition of the hydroid community, these factors also influence the morphology and general biology of the individual species. The adaptations and reactions of hydroids to different intensities of the various environmental factors and to their combinations are reported.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00310.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.A quantitative survey (18 stations) of the subtidal soft bottom macroinfauna in an estuary of the south Chilean coast was conducted during January, 1980. The map of sedimentological facies elaborated for the Queule River Estuary shows sandy bottoms in the outlet and upper part of the area studied, while the middle part is occupied by muddy sand. The ordination of stations by Principal Component Analysis is fundamentally defined by mud and gravel percentage and is, in general, concordant with the distribution of sediments in the facies map. A total of 17,405 animals was collected (16 taxa),Polychaetabeing the dominant group in density (77.47%) and biomass (73.4%). The maximum number of species was obtained outside the mouth of the estuary, while maximum densities and biomass were obtained in the middle of the estuary.The Factor Analysis performed with the abundances data of the most abundant species rendered the ordination of two groups of stations (concordant with a Cluster Analysis) in the Q‐mode and two groups of species in the R‐mode. One group of stations is restricted to sandy habitats of the outlet area and is dominated by suspension feeders. The other, in the middle and upper part of the estuary (muddy sand or sandy bottoms with a higher percentage of organic matter), is dominated by deposit feeders. Between these two groups, significant differences in sedimentological variables (sand, mud, and organic matter percentage) were detected. Each of the two delineated groups of species corresponds to the groups of stations, showing that most of the taxa can be combined in faunal assemblages with preference for different types of substr

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00311.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.The influence of some exogenous factors (temperature, day‐length, starving, amputation of caudal segments) on oocyte development and on somatic growth in the polychaeteAnaitides mucosahas been investigated. Animals from Wimereux (France) were maintained in the laboratory from September to April. Like in other polychaetes with a breeding season in early spring oocytes grow in two waves. The second one only occurs after spawning of the first and shows an accelerated growth. Low temperatures (5oC) (i. e.winter conditions) are essential for a qualitative normal development of the first wave, whilst higher temperatures (15oC) totally suppress maturation of oocytes and reproduction. The influence of day‐length, however, is probably without importance. Starving and amputation of caudal segments to do not produce significant changes in the growth rate of oocytes, either. In contrast, the somatic growth is most extensive at high temperatures (15oC) and long‐day photoperiods (LD 16/8).ZusammenfassungEine normal verlaufende Entwicklung der Oocyten vonAnaitides mucosafindet nur während einer längeren Periode mit niedrigen Temperaturen (5oC) statt.Hungerbedingungen und Regenerationsprozesse, ausgelöst durch die Amputation caudaler Segmente, beeinflussen die Entwicklung der Oocyten bei niedrigen Temperaturen nicht. Die Oocytenentwicklung ist nicht abhängig von der Photoperiode.Das somatische Wachstum ist dagegen an höhere Temperaturen (15oC) und in geringerem Umfange an Langtag‐Bedingungen (LD 16

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00312.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.Microbial colonization on the leaves of a shoot of the mediterranean seagrassPosidonia oceanica(L.) DELILE was studied using Scanning Electron Microscopy. Methods of field ecology such as transect, random plot and stratified sampling survey were applied to the microbial niveau to gain both qualitative and quantitative information on the microbial assemblage.While macro‐epiphytic growth was significantly greater on the outer leaf sides, microbial colonization density was significantly higher on the inner leaf sides, both on leaf surface and epiphyte surface. Diatoms colonized the surface of incrusting algae and epiphytic animals in significantly lower numbers than thePosidonialeaf surface and were absent on erect epiphytic algae. Bacterial densities on epiphyte surfaces even exceeded values of the corresponding leaf surfaces on algal thalli near the leaf tips and on old leaves. Diatoms reach highest mean density on mature leaves and close to the leaf tips, while bacteria reach their greatest density on the oldest leaf and closer to the leaf base. Diatom density in general increases with exposure time of plant surface, while greatest bacterial density was observed at 7–10 weeks exposure. Basal leaf parts on younger leaves were dominated by rod‐shaped bacteria, while distal leaf parts and old leaves were dominated by small coccoid bacteria. Surfaces of epiphytic algae were always distinctly dominated by small coccoid bacteria, and edges of thalli attracted high microbial densities. Microbial biomass (calculated from cell volumes using standard conversion factors) amounts to 2.3 g dry weight m‐2in thePosidoniastand where the shoot was sampled.The observed patterns of epiphytic colonization are interpreted as the result of a complex, dynamically changing system of interactions both within the epiphytic community and between the epiphytic community, the host plant, and it's environment. A model of the organization of the epiphytic community onPosidonialeaves is presented. “Ultra‐ecology” is a term introduced to denote a type of SEM research in the micro‐environment which is analogous toin situinvestigation in “macroscopic

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00313.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.The long‐spined sea urchinDiadema antillarumhas been reported to be the major food item of the queen triggerfish,Balistes vetulain the Caribbean. This sea urchin has undergone a massive mortality on reefs throughout the Caribbean during 1983. The dietary habits of twenty‐three queen triggerfish from patch reef habitats in Belize were examined. It was found that crabs and chitons now form the major dietary items whenD. antillarumis not available. It is suggested that this predator, which was previously specialized on a single food item, is able to shift resource utilization in the absence of its primary food source, and that the queen triggerfish can capture diverse prey from a wide variety of habit

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00314.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1984.tb00315.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY