摘要:

Abstract.In situfeeding habits of the cyclopoid copepodsOncaea venusta, Corycaeus amazonicus, Oithona plumifera, andO. simplexwere investigated by scanning electron microscope examination of fecal pellets, the contents of which reflected copepod gut contents upon capture. Peilet contents were compared with assemblages of phytoplankton present in surface waters at times of copepod collection. All samples were from the northern Gulf of Mexico. All four copepods fed upon phytoplankton andO. venustaalso ingested other crustaceans. Dominant components of fecal pellets generally did not mirror those of available phytoplankton assemblages. In some cases,O. venustaingested primarily larger‐sized particles even when these were not most abundant, and in other cases it did not ingest large cells even when they were present in bloom concentrations. The presence of small (<2–5 urn diameter) centric diatoms inO. venustapellets suggests the possibility of feeding by mechanisms other than suspension or raptorial feeding. Limited observations suggest thatC. amazonicusandO. plumiferamay feed raptorially on larger particles even when these are not particularly abundant, and that the smallO. simplex(<500 nm total length) feeds mainly upon nanoplankton. It appears that cyclopoid feeding mechanisms are complex, and likely more so than those of many calano

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00165.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract.Important intertidal sabellarian reefs are built by the polychaeteSabellaria alveolata(LINNÉ) in the Mont Saint‐Michel Bay in Normandy at Champeaux (France). Typical profiles and plans were done over a ten year period. At the same time, population dynamics were examined during the last six years. At this site a nearly complete morphological cycle spread itself over more than ten years. Initially built on rock substrate (primary settlement phase), the studied reefs actually lie on a sandy shore. The growth phase begins by stages of balls which are then joined with new settlements between or on older tubes (secondary settlement). This phase comes to an end with an important platform stage. Then, the destruction phase brings us back to dead eroded reefs on which new worms can settle (secondary settlement). This cycle seems to be independent of the age of the living population, although new settlements of young worms and also sufficient hydrodynamics seem necessa

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00166.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract.When simultaneously presented with equal numbers of four sizes of clumpedMytilus californianus(20, 35, 55 and 85 mm shell length),Pisaster ochraceus(arm length of 70‐110mm R) showed a preference for the medium sizes (35 and 55mm length). Prey‐size preference was positively correlated with predator size. Mean prey‐digestion times (insertion of the stomach, opening of the valves and digestive period) decreased significantly following fiiing of an artificial gape between the valves of mussels. When presented with different sizes of clumped filed mussels, starfish still chose medium mussels, indicating that stomach insertion, valve opening, and digestion rate may not be important constraints determining size selective predation. Measurements of the force required to dislodge mussels from the substratum and conspecifics showed an increasing exponential relationship with mussel size. Size selective feeding may be an energy maximizing and time minimizing strategy, where energy gained from choosing larger mussels is balanced against disproportionately increased costs in energy and time of removing large mussels from the subst

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00167.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract.The feeding and resting patterns ofLittorina angulifera, the southern periwinkle, were observed in mangrove habitats of Belize (Central America). The snails feed predominantly on the surface of prop roots ofRhizophora manglein a narrow zone at and above the mean high water mark. This area contains large numbers of hyphae and chlamydospores of an unidentified marine fungus(Deuteromycetes)and filaments of a chlorophyte(Chlorochytriumsp.). Both organisms are ingested by snails whose digestive tracts and fecal pellets contain ground‐up cork cells, tricho‐sclereids, tracheids, calcium oxalate crystals, fungal hyphae and chlamydospores, as well as undigested cyanobacteria. Most fungal particles pass through the gut unchanged. During dry periods,L. anguliferais in a dormant state, usually attached with dried mucus to leaves high in the tree, causing necrotic, crescent‐shaped marks. The leaf tissue under the area of shell attachment becomes meristematic, separating dead tissues from healthy mesophyll. The snails detach during rainfall and move downward to the feeding sites on the prop

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00168.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract.Macropetasma africanusis an important component of the nearshore macrofauna in South African marine waters. Juveniles utilize high energy surf zones as nursery and maturation areas before offshore migration to spawning areas. Samples were taken from two surf zone areas and an offshore spawning area over a two year period. Spatial, seasonal, and diel variations in diet, established from stomach content analysis (N = 1020), indicate thatM. africanusis an omnivorous feeder with a diet reflecting general food availability in the environment. Five major food groups were identified. Detritus was the most important food group identified in a medium energy surf zone and offshore spawning area. Phytoplankton was the major food group utilized in a high energy surf area characterized by phytoplankton blooms. Crustaceans were an important component of the diet in all three areas sampled and the remains of copepods, ostracods, isopods, amphipods, and mysids were identified. Benthic macrofauna and meiofauna are not important components of theM. africanusdiet in the turbulent surf zone areas but appear more important in the offshore area. Feeding behaviour is adapted to turbulent conditions found in surf areas and the passage of food through the foregut is rapid.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00169.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Abstract.The marine plant communities of the littoral zone in different biotopes of the Greek coasts were investigated in 1980‐81. Seasonal distribution and variation of marine plant biomass were assessed. The communities ofCystoseira crinitaandC. compressawere outstanding with maximum biomass during the summer months.Corallina officinalisandPterocladia capillacea + Viva rigidacommunities predominated with maximum biomass in autumn and exhibited a decrease in winter, except in stressed biotopes. The species diversity and productivity of seaweeds along the Greek coasts are interpreted in relation to a number of environmental parameter

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1986.tb00170.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY