Search results for "Trophic level"
showing 10 items of 324 documents
A quantitative review of the lifestyle, habitat and trophic diversity of dinoflagellates (Dinoflagellata, Alveolata)
2012
This study reviews the trends in the lifestyle, habitat distribution and trophic diversity of the 2377 described species of dinoflagellates (Dinophyceae). Most of the dinoflagellates inhabit marine waters, whereas 17% of the total species have colonized continental waters. Dinoflagellates are dominated by planktonic species, while benthic forms represented 8% of the species. From the total number of species, 49% are heterotrophic (devoid of plastids), while 51% of the species have been reported with plastids (that does not strictly imply autotrophy). All the basal dinoflagellates (ellobiopsids, Duboscquodinida, Syndiniales) are heterotrophic, with the exception of a few Noctilucales (Spatul…
Seasonality of coastal phytoplankton in the Baltic Sea: Influence of salinity and eutrophication
2005
Abstract In this study long-term (1984–2001) phytoplankton and physico-chemical monitoring data representing different salinity regimes of the Baltic Sea were compiled from HELCOM, national and regional databases. The aim was to define seasonal succession patterns of phytoplankton in seven different areas of the Baltic sea, characterised by different salinity, climate, and trophic conditions and to delineate a set of phytoplankton community indicators that are independent of season and salinity, but indicative of trophic status of different coastal areas. The cluster analysis of the combined data set resulted in eight phytoplankton community types, common for all locations, and characterise…
Lipid-rich zooplankton subsidise the winter diet of benthivorous Arctic charr (Salvelinus alpinus) in a subarctic lake
2013
Summary Generalist fish species commonly act as important links between littoral and pelagic habitats and food-web compartments in lakes. However, diet and habitat links may depend significantly on seasonal availability of, and qualitative differences between, littoral and pelagic prey and on fish size. Despite increasing interest in food-web dynamics, little is known about the seasonal changes in, or qualitative differences between, littoral and pelagic trophic pathways supporting generalist fish species in high-latitude lakes. We used stomach contents together with analyses of stable carbon and nitrogen isotopes and fatty acids to study the winter and summer diet of generalist Arctic char…
Composition and Trophic Structure of Detrital Food Web in Ant Nest Mounds of Formica aquilonia and in the Surrounding Forest Soil
1998
Community composition and food web structure of soil decomposer biota in relation to various habitat properties were compared between upper parts of red wood ant (Formica aquilonia) nest mounds and the adjacent forest soil. For a description of trophic structure of the decomposer community in the two habitats, soil decomposers were classified into 14 trophic groups. Classification of the taxa into three habitat preference categories resulted in a clear division of the fauna into either soil or nest specialists, relatively few taxa falling between these two groups. A large majority of the nest specialists belonged to a non-myrmecophilous soil decomposer fauna so far largely overlooked in stu…
The trophic structure of the pipefish community (Pisces: Syngnathidae) from a western Mediterranean seagrass meadow based on stable isotope analysis
2004
Syngnathus abaster andSyngnathus typhle (Pisces: Syngnathidae) from a dense Cymodocea nodesa meadow in the western Mediterranean Stagnone di Marsala (Italy) were studied using δ13N and δ15N analysis. Because of the presence of these two species in the same habitat and the specialized parental care by the male, the effect of species and sex on the isotopic composition was also studied to investigate the different feeding strategies between and within species.S. abaster andS. typhle exhibited enriched13C and15N values throughout the sampling period (mean ±SE, δ13C =−10.5±1.8‰ and−10.8±2.0‰, δ15N=11.9±0.7‰ and 10.6±1.0%., respectively), suggesting that these species receive their energy mainly…
Trophic Transfer of Trace Elements in an Isotopically Constructed Food Chain From a Semi-enclosed Marine Coastal Area (Stagnone di Marsala, Sicily, M…
2012
Trace element accumulation is particularly important in coastal and transitional environments, which act as contaminant buffers between the continental and marine systems. We compared trace element transfer to the biota in two locations with different open-sea exposures in a semi-enclosed marine coastal area (Stagnone di Marsala, Sicily, Italy) using isotopically reconstructed food chains. Samples of sediment, macroalgae, seagrasses, invertebrates, fish, and bird feathers were sampled in July 2006 and analysed for stable carbon and nitrogen isotopes (δ(13)C, δ(15)N) and trace elements (arsenic [As], cadmium [Cd], total mercury [THg], and lead [Pb]). Trophic magnification factors were calcul…
Soil microbial and microfaunal communities and organic matter quality in reindeer winter and summer ranges in Finnish subarctic mountain birch forests
2008
Abstract Reindeer husbandry has significant influences on the aboveground plant communities and the structure of the mountain birch forests in the Fennoscandian subarctic. We investigated how the reindeer-mediated aboveground changes affect soil microbial and microfaunal communities and enzymatic activities. We hypothesized that in areas with intensive summer browsing by reindeer, the carbon flow to belowground is reduced, but the carbon substances are more readily degradable. This is likely to influence both the abundance and the trophic structure of microbial and microfaunal communities. However, despite large differences in the vegetation, the reindeer ranges did not differ in the amount…
Responses of microbial-feeding nematodes to organic matter distribution and predation in experimental soil habitat
2001
Abstract Soils are spatially heterogeneous environments, a condition which is likely to affect the structure and function of soil food webs. To study the influence of soil organic matter distribution on decomposer food webs, we established microcosms that contained either: (1) large patches of initially sterile humus-litter mixture placed within sterile sand matrix (creating a large-patch habitat; LPH); or (2) blend of sand and humus-litter mixture (creating a small-patch habitat; SPH). Ten species of bacteria and ten species of fungi, and two bacterial-feeding ( Acrobeloides tricornis , Caenorhabditis elegans ) and two fungal-feeding ( Aphelenchus avenae , Aphelenchoides sp.) nematodes wer…
Vertical stratification and trophic interactions among organisms of a soil decomposer food web – a field experiment using 15N as a tool
2002
Abstract In this field study, we explored the spatial segregation between the litter- and humus-inhabiting organisms of the detrital food web using 15 N-isotope technique. The study was established in 11 × 11 m plots fertilized with 15 N-labelled urea. Ten years after urea application, soil samples were taken, both from the litter layer and the combined F+H layer. The samples were analysed for N content and the proportion of 15 N in (i) the residual organic matter in the litter and F+H layer (excluding microbes), (ii) microbial biomass, and (iii) various feeding guilds of soil fauna. The basal resource, soil microbes, and the fauna were more enriched with 15 N in the F+H layer than in the l…
and variability in Posidonia oceanica associated with seasonality and plant fraction
2003
Abstract The carbon and nitrogen isotopic compositions of fractions of the seagrass Posidonia oceanica (L.) Delile in a Mediterranean shallow environment (Stagnone di Marsala, western Sicily) were investigated seasonally throughout 1998. The stable isotope ratios of seagrass leaves (intermediate and adult), rhizomes, leaf litter and aegagropiles were compared over 1 year in order to distinguish between seasonal and plant part variability. Significant differences in the isotopic composition tested using ANOVA were observed as a function of both plant fraction and season. There was an overall trend towards less discrimination against 13 C in summer (average δ 13 C ∼ −10‰) than in winter (aver…