摘要:

Abstract.The macrofaunas associated with the three morphologically different North Aegean Sea sponge speciesAgelas oroides, Aplysina aerophoba, andAxinella cannabinawere compared. The faunal abundance was not related to sponge surface area for any of the three species. Each sponge species supported a significantly different number of individuals per unit canal volume;A. aerophobasupported the most,A. oroidesthe least.A. aerophobasupported the highest species richness,A. cannabinathe lowest. Canal volume was a good predictor of associated faunal abundance and species richness for two of the three sponge species. Faunal abundance was also directly related to sponge mean canal diameter. The species composition of associated fauna was similar onA. aerophobaandA. oroidesand significantly different onA. cannabina.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.A total of 24 samples fromSabellaria alveolatareefs have been collected and subjected to cluster analysis using the trophic dominance of each feeding guild as grouping variables. The result is the arrangement of samples by colony physical structure andS. alveolatadominance.Relating cluster groups to reef development phases reveals an inverse relationship between reef growth and the organization of the associated polychaete taxocoenosis. During the growth phase of the reef,S. alveolatadominates the community, excluding other taxa from colonization. Growth is followed by the destruction phase. Negative physical and biological factors for reef enlargement may open patches on the reef surface, allowing recruitment of other species and colony erosion. The end of this phase is represented by eroded reefs with high structural complexity and high species richness.SummarySabellaria alveolatareefs reported from 13 localities in the study area have been classified according to their structural features into two main types: a) developed reefs, with considerable volume and a shape independent of the underlying substrate and b) eroded reefs, which form tiny encrusting plates covering the substrate. Based on cluster analysis each one of these may be subdivided according to SAQD values.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.A photo transect along the continental slope off Morocco, Northwest Africa revealed an extensive population of the hexactinellid spongePheronema carpenteri(thomson, 1869). The population forms a distinct band parallel to the depth contours between 740 and 820 m. Because of the long persistence of dead hexactinellid skeletons, living and dead individuals ofP. carpenteriwere recorded, together with the spicular remains of disintegrated individuals. Furthermore, the presence of small individuals and that of other epifaunal elements were recorded. The peaks of abundance of dead and living sponges, respectively. are not at the same depth, the maximum abundance of living individuals being above that of the dead ones; small,i.e., probably youngP. carpenteriindividuals were observed only in the upper zone. This can be interpreted as a successional phenomenon,i.e., the population ofP. carpenterihas apparently ‘moved’ slowly up the slope. The fauna associated with theP. carpenteripopulation along the Moroccan coast seems to be much poorer than that associated with another band‐shaped population in the Porcupine Seabight investigated by Bett&Rice(1992). indicating that the presence of dense hexactinellid populations does not invariably lead to conspicuous benthic faunal enric

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00420.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.The ophiuroidAmphiiodia urticaLymanis presently under study as a potential wastewater discharge indicator species from ocean outfalls in the Southern California Bight. On the San Pedro Shelf, the maximum abundance ofA. urticawas found at depths from 30 to 100 m, and in sediment with a median grain size of 0.085 nim, 60–80% sand. 15–30% silt, 0–37% clay, and 0.2–0.5% TOC. The mean abundance ofA. urticafluctuated annually with a slight increase from 1977 through 1993.The hypothesis was posed that the distribution and abundance ofA. urticais not influenced by an ocean outfall and its operation on the San Pedro Shelf. Based on long‐term (1977–1994) and intensive (2860 samples) sampling. the hypothesis was rejected. However, the effect of the outfall is not clear because sediment bioassays from test stations and controls produced no significant differences in survivorship and growth of juveniles.Amphiodiapresently occupies areas within the Zone of Initial Dilution (ZID) where it was not found during the mid‐1970s and early 1980s. While recognizing thatA. urticaabundance responds to proximity to the outfall, the mechanism for this response is still unclear. The application of a single species as a bioindicator is not recommended, and most certainly not without fully essing its role in community structure

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.The height of seagrass canopy was manipulated in experimental plots in meadows of the fine‐leaves seagrassCymodocea nodosaat two sites in the Mediterranean Sea, la Lagune du Brusc, Iles des Embiez near Toulon, and I'Etang de Diana on Corsica. Epifauna (small motile invertebrates associated with the seagrass canopy or sediment surface), was collected at night at both sites, and during the day at Diana only, from three treatments: full seagrass canopy, reduced canopy, and canopy removed entirely. Although epifaunal assemblages from the two sites were different, treatment modification had the same effect at both sites when analysed using multivariate ordinations. Abundance and biomass of total epifauna and of key taxa were all reduced in line with decreasing seagrass cover at both sites at night. The effects of treatment modification on epifauna during the day showed the same trend but were of greater magnitude, both for assemblages and for total abundance and biomass. At both sites and at both times, the fauna of plots from which seagrass had been cut tended to be dominated by animals of higher biomass than the fauna of plots with full canopy. Epifauna form the major dietary component of small fish inhabiting shallow, sheltered embayments. These results are therefore consistent with a model in which reduced abundance of fish associated with reduced seagrass canopy is explained by a reduction in food availabilit

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1996.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY