摘要:

Abstract.The population ecology and dynamics ofCuprella equilibrawere studied in a lagoon estuary of the Northern Adriatic Sea during 1985 to 1986. The breeding activity showed peaks in April and September and a decrease in summer due both to high temperatures and a dystrophic crisis; breeding stops in winter. Females produced more than one brood per year.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00390.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.A seasonal sampling program of five stations off the Island of Rhodes (SE Aegean Sea) was carried out in 1983–1984. Temperature, salinity, Secchi disk transparency, P‐PO4, N‐NO3, N‐NO2, N‐NH3, Si‐SiO2, and chlawere measured and phytoplankton species recorded. Cell concentrations and chlavaried seasonally. with the highest values in summer (l.2 times 104‐1‐‐1total mean cells; 0.13 mgam‐3total mean chla) and the lowest in winter (2.3 times 103, 1‐‐1total mean cells; 0.06 mg.m‐‐total mean chla). A variation in cell abundance among stations was also noted. Quantitative relationships among the recorded taxa showed that diatoms and dinoflagellates were richer in species composition (88 and 58 total species, respectively) than coccolithophores (8 species) and other flagellates (8 species). Comparison of phytoplankton samples from different depths and stations by cluster analysis showed an irregularity or discontinuity in species associations. The SE Aegean Sea was characterized as oligotrophic on the basis of the estimated nutrient and phytopl

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00391.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.Experiments were conducted to determine the decomposition rate of mangrove wood in two areas of differing water nutrient concentrations. Stakes were prepared from prop roots ofRhizophora inangleand from branches ofAvicennia. ConocarpusandLagguncularia. and tied in the natural habitat at two sites—Man‐of‐war Cay (high nutrient concentrations) and Twin Cays (low nutrient concentrations) — off the Belize coast. The stakes were retrieved after 4–24 months and the vertical zonation and succession of higher marine fungi was recorded. Consumption of wood by shipworms (Teredo bartschi), the major decomposers, was measured by digital analysis of the area of wood consumed by these boring organisms.SummaryA total of 20 species of marineAscomycotina, 2Basidiomycotina, and 6 anamorphic fungi were identified from the experimental stakes. Differences in species composition between the two sites of Twin Cays and Man‐of‐war Cay (Belize) were observed, as well as a certain degree of patterning in the vertical distribution of fungi. AmongAscomycotina, members ofHalosphaerialesshow a definite tendency to thrive at greater depths than other species. Mangrove decomposition by shipworms was clearly higher in the nutrient‐rich waters of Man‐of‐war, where the stakes were already heavily riddled after 8 months and had mostly disappeared after 2 years, while they were still intact at the other site. No significant difference in degradation of the 4 species of

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00392.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The local distribution and seasonal variation of Fe, Pb. Zn, Cu. Cd, Na. K, Ca, and Mg concentrations inCymodocea nodosa(ucria) Aschers., one of the most abundant seagrasses of the area. as well as their concentrations in the sediment and seawater were studied in the Gulf of Antikyra (Greece). The gulf is characterized by a bauxitic substrate and waste discharges from an aluminiumproducing factory. Many of the metals investigated constitute components of the two above‐mentioned metal sources.The mean metal concentrations (± SE) in the seagrass decreased in the order: Ca>Na>K>Mg>Fe>Pb>Zn>Cd>Cu.At the sampling stations A1, A2, A3, B3, and C1, where sufficient data was available for statistical analysis. the concentrations of metals in the plant did not vary significantly among stations (P>0.05).Metal concentrations inC. nodosarevealed two patterns of significant seasonal variation. The first pattern involved Fe, Cd, Na. and Ca and was characterized by high mean concentrations in summer and autumn. A reverse pattern was shown by Pb, Cu. and Mg. These patterns are discussed in relation to the growth dynamics. and leafage of the seagrass. the metal concentrations in the environment. the intermetal correlation, etc.Cu, Cd, Pb, and Ca concentrations in the seagrass were significantly correlated with those in the sediment, whereas a direct relation of plant and seawater concentrations was obtained only for Ca and Mg. The intermetal correlation matrices in C.nodosashowed synergistic interactions between Cd‐Ca, Pb‐Mg, Fe‐Ca, Cu‐Pb, Na‐K, and Na‐Ca and antagonistic interactions between Cd‐Pb, Cd‐Mg, and Pb‐Ca.The Cu, Cd, and Pb concentrations and the maximum Fe concentration inC. nodosain the Antikyra Gulf are high compared with species belonging to theCymodorroideaesubfamily from other geographical areas.SummaryFe, Cu, Pb, Cd, Ca, Na, and Mg concentrations inC. nodosadisplayed significant seasonal variation. The mean concentrations of Fe, Cd, Na, and Ca were high in summer and autumn. In contrast, Pb, Cu, and Mg concentrations were high in December and March. The concentrations of Fe, Cu, Zn, Cd, Pb, Na, K, Ca, and Mg did not vary significantly among the stations A1, A2, A3, B3, and C1of Antikyra Gulf (Greece). Significant correlations were obtained between Ca and Mg concentrations in the seagrass and seawater and between Cu, Cd, Pb, and Ca concentrations in the plant and the sediment. Cd‐Ca, Pb‐Mg, Fe‐Ca, Cu‐Pb, Na‐K, and Na‐Ca showed positive correlations, whereas Cd‐Pb, Cd‐Mg, and Pb‐Ca showed negative correlations in the plant. Finally, the mean metal concentrations inC. nodosadecreased in the order: Ca>Na>K>Mg>Fe>Pb>Zn>Cd>Cu.The concentrations of the heavy metals Cu, Cd, and Pb inC. nodosuin the study area are high compared with species belonging to theCy

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00393.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The hypothesis that benthic community structure of soft‐bottom macrobenthos does not change throughout the Newport Submarine Canyon, California was tested with a set of quantitative VanVeen(0.1 m2) samples down the canyon axis. There was a marked break in community structure between Station C4 (187 m) and Station C5 (324 m). Comparison of the present study with work conducted earlier indicates that mean number of species, abundance, and biomass were not significantly different between 1962 and 1978. Within the canyon, species diversity was high compared to 12 other southern California canyons. This difference was mainly due to sampling effort and the inactive nature of the Newport Canyon.SummaryOver 500 species are identified from Newport Canyon, California from 1978 to 1990. The diversity of soft‐bottom macrobenthos in shallow to intermediate depths of Newport Canyon is much higher than in other southern California canyons (Hartman, 1963). This difference is mainly due to sampling effort and the inactive nature of Newport Canyon which facilitates the maturation of soft‐bottom communities; in contrast to active canyons which through turbidity currents frequently disrupt the water‐sediment interface. Conditions within Newport Canyon have been stable for benthic community structure for at least 16 years and probably closer to 25 years. The hypothesis examined here shows that community structure is not homogeneous with depth along its axis, but has a marked break between 187 m and 324 m. Finally, we are now in a position to examine hypotheses concerning the effects of an ocean outfall on benthic community structure between the shelf and the

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00394.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract.The composition of the algal diet ofSiganus luriduswas compared with that of the algal vegetation found in fish habitats along the Mediterranean coast of Israel. North‐south differences in the diet were found and reflected differences in the available algal resources as well as in algal species selected.In the northern area, the diet and the algal selection differed considerably betweenS. luridusand a congeneric Lessepsian migrant siganid.S. rivulatus, whereas in the southern area the two species showed similarity in feeding.A comparison is made between the Mediterranean populations and those of the tropical Red Sea Gulf of Elat (Aqaba). The diet partitioning in the Northern Mediterranean resembles that found in the Gulf of Elat. where the realized diet may be related to strong competition between herbivores in combination with availability of numerous edible algal species. There. the two siganids showed different preferences. In the Northern Mediterranean, competition is probably lower. since there are fewer herbivorous fish species. while numerous good algal habitats (rocky areas) enable selection. By contrast, rocky algal habitats are scarce in the southern area; this implies that the total amount of algae available to choose from is smaller there.The similar diets and preferences in the southern part of the Mediterranean indicate scarcity of preferred food species. as the fishes fed mainly on small filamentous species of the algal turf on the bottoms.SummaryThe algae and seagrasses in gut contents of two Lessepsian migrants were analysed:Siganus rivulatusandS. luridusfrom both Red Sea and eastern Mediterranean locations. The quantitative and qualitative composition of the diet was compared to that of the algal and seagrass vegetation in four regions: the southern and northern basins of the Gulf of Elat and the southern and northern area in the Mediterranean along Israel's coast.In the original environment of the fish in the southern basin of the Gulf of Elat, a variety of large brown algae as well as fleshy and soft red algae, green and blue‐green algae and seagrasses inhabited the coral reefs and adjoining areas, all of which were accessible to the fish. There,S. luridusmainly fed on and selected large brown algae, whileS. rivulatusmainly fed on and selected fleshy and soft red algae. In the Mediterranean, horizontal platforms at about sea level are covered with algae. The small tidal range makes these sites mostly inaccessible to grazing fish. In the submerged habitats where the fish fed, calcareous red algae dominated. In the southern area both siganids fed on and selected small filamentous algae as found in the algal turf. In the northern area S.luridusfed on and selected large brown algae,S. rivulatusonUlvaand fleshy red algae. The algal partitioning in the Red Sea disappeared in the southern area of the Mediterranean as an adaption to the environment. It developed in the northern area probably due to the prevalent rocky areas with their algal habit

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00395.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1995.tb00396.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY