摘要:

Abstract.The diet of the copepodAnomalocera ornatawas examined by comparing contents of fecal pellets produced on natural diets with assemblages of available phytoplankton. Samples were collected in continental shelf and slope waters of the northern Gulf of Mexico. A wide size and taxonomic array of phytoplankters was ingested, and remains of phytoplankton taxa in fecal pellets reflected the composition of phytoplankton assemblages in the water. Absence of crustacean remains in fecal pellets suggests thatA. ornatafeeds primarily as an opportunistic grazer.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00138.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Sporophytes ofLaminaria digitataandL. saccharinawere collected from the shore at different times of year. Intact sporophytes of both species, and discs cut fromL. digitatalamina tissue were maintained for several weeks in laboratory cultures under various nitrate, phosphate, temperature and daylength regimes. Substrate‐saturated uptake rates of approximately 24 μgN g dry weight‐1h‐1from 20 μM nitrate and 8 μgP g dry weight‐1h‐1from 10 μM phosphate were more than sufficient to account for internal nitrogen and phosphorus accumulation. Other nitrogen sources ‐ nitrite, ammonium and urea ‐ were also taken up, independently of each other, and supported growth.During the late spring decline of ambient nutrient levels, when growth rates on the shore also decline markedly, enrichment with nitrate (15 μM) and phosphate (3μ) together prevented this decline and also maintained peak photosynthetic rates (net photosynthesis = 10.4 μlO2cm‐2h‐1) which otherwise dropped to 4.5 μO2cm‐2h‐1over 47 days at ambient nutrient levels (0.5 μM nitrate and phosphate). Slow summer growth rates in June/July were enhanced to greater than spring peak values by combined nitrate (7.5 μM) and phosphate (1.8 μM) enrichment; neither was sufficient alone, although the individual nutrients were accumulated internally. A lesser, but significant enhancement was also achieved in September.In midwinter, nutrient enhancement itself (10.5 μM nitrate and 3.0 μM phosphate) had a small effect on growth rates only if summer water temperature (15°C) was used, but the dramatic effect of an increased photoperiod (7.5 to 17.5 h) was in excess of that expected for the increased radiant energy available. This was found to be due, at least inL. digitaiadiscs, to the re‐establishment of a surface meristoderm in the dormant winter tissue; this was particularly active with high phosphate supply. Growth of the new lamina in January on the shore was much reduced if the old lamina was removed, although the time of initiation of new growth remained unchanged. In the laboratory, the old lamina was found to be a source of nitrogen for new lamina but not of fixed carbon or phosphorus. New lamina photosynthesis, manifest as mannitol accumulation, was directly proportional to phosphate supply up to at least 7.5 μM phosphate. Mannitol accumulation was then suppressed by a nitrate supply above 12 um, presumably by diversion of fixed

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00139.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.The distribution ofM. muellerieggs throughout the Adriatic Sea were studied in relation to environmental conditions. Eggs were present in all seasons, with the highest concentrations in the small region of the Jabuka pit (273m depth). The authors point out that the geomorphological, hydrographic and trophic conditions in this small region of the Adriatic are favourable for the presence of greaterM. muelleripopulations.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00140.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.The utilization of the spatial resources of refuge type, size and depth placement is investigated in the three sympatric species ofAcanthemblemariaat the cape region of Baja California, Mexico.A. balanorumoccupies barnacle testes(Balanus tintinnabulum), A. macrospilusoccupies barnacles and mollusk tubes (vermetid gastropods and pholadids), andA. crockerioccupies only mollusk tubes (pholadids). Refuge diameter overlap is higher than overlap in depth.A. crockericonsistently occupies depths below 5m. Competition experiments for barnacle refuges among the three species indicate thatA. balanorumis a superior competitor for such refuges. Prior residency of a less superior species changes the outcome of refuge competition in its favor. The morphological specialization ofA. balanorumandA. macrospilusis evident in a high correlation between head size and standard length.A. balanorumselects refuges with entrance diameters highly correlated to standard length.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00141.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.A marked increase in the biomass ofCliona delitrixinfestingMontastrea cavernosasubstrate occurred in a portion of the Grand Cayman fringing reef affected by the discharge of untreated fecal sewage. It is suggested that the six‐fold increase in bacteria biomass (both “coliforms” and natural marine bacterioplankton) in reef waters receiving the sewage effluent is linked to a five‐fold increase in sponge biomass at the polluted site relative to a control site. The elevated density ofC. delitrixbiomass signifies a similar increase in the amount ofM. cavernosaskeleton that has been eroded by this sponge and reduced to silt‐sized sediment. Thus, the proliferation of a bioeroding organism in the sewage‐stressed environment has caused a shift in the carbonate balance

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00142.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1985.tb00143.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY