Search results for "Benthic zone"
showing 10 items of 265 documents
The fate of organic matter sources in coastal environments: a comparison of three Mediterranean lagoons
2008
Trophic processes in coastal lagoons are strongly influenced by freshwater inputs and water exchanges with the sea. In recent years, stable isotope analysis has become a widespread and reliable method for the examination of trophic structure over time and space, also in complex ecosystems such as coastal lagoons. Stable isotopes of carbon and nitrogen were studied in primary producers and consumers to identify organic matter source pools from terrestrial, benthic and pelagic environments and to characterise the trophic structure in three Mediterranean coastal lagoons (Lake Fusaro, the Lake of Sabaudia and Stagnone di Marsala). The results highlighted the negligible importance of terrestrial…
Short-term recovery of benthos following disturbance from stream habitat rehabilitation
1994
The recovery of benthic macroinvertebrates after disturbance from stream rehabilitation was studied in the River Livojoki, northern Finland. The stream that had been channelized for log transport was rehabilitated on 1 July 1992 by digging holes and inserting boulders. We measured habitat characteristics and sampled benthic animals before and after rehabilitation, including an unrehabilitated control site. The immediate effect of rehabilitation was a slight decrease in the abundances of benthic insects. Recolonization occurred rapidly, within 10 days. Disturbance of the rehabilitation did not have a detectable effect on the macroinvertebrate community. Most species-level changes and communi…
Biological quality metrics: their variability and appropriate scale for assessing Streams
2006
The concept of spatial scale is at the research frontier in ecology, and although focus has been placed on trying to determine the role of spatial scale in structuring communities, there still is a further need to standardize which organism groups are to be used at which scale and under which circumstances in environmental assessment. This paper contributes to the understanding of the variability at different spatial scales (reach, stream, river basin) of metrics characterizing communities of different biological quality elements (macrophytes, fishes, macroinvertebrates and benthic diatoms) as defined by the Water Framework Directive. For this purpose, high-quality reaches from medium-sized…
How picky can you be? Temporal variations in trophic niches of co-occurring suspension-feeding species
2014
Abstract Suspension-feeders largely dominate faunal communities on rocky shores and compete for food using different feeding strategies. We used stable isotopes to assess the individual specialization within common suspension-feeder populations and to evaluate both inter-specific and intra-specific differences in food source exploitation. Trophic niches were characterized by metrics calculated in a space formed by mixing model outputs. Honeycomb worms ( Sabellaria alveolata ), blue mussels ( Mytilus edulis ) and barnacles ( Chthamalus montagui ), as well as three organic matter sources (benthic microalgae, phytoplankton and green macroalgae) were surveyed over a year using stable isotopic c…
Spatial community concordance of summer phytoplankton and profundal macroinvertebrates in boreal lakes
2014
Reliance of profundal benthic macroinvertebrate assemblages on epilimnetic algal production — a key element of pelagic–benthic coupling — is a well-recognized phenomenon in the literature but the details are still poorly understood. In particular, the importance of taxonomic composition of algal communities and associated qualitative aspects of the settling material to benthic invertebrates is poorly known. We addressed this issue by investigating concordance of summer phytoplankton and profundal macroinvertebrate community composition using data from 47 boreal lakes. We examined community variation and environmental correlates of phytoplankton and macroinvertebrates with nonmetric multidi…
Areas of endemism in the Antarctic - a case study of the benthic hydrozoan genusOswaldella(Cnidaria, Kirchenpaueriidae)
2010
Aim The aim of this study is to investigate areas of endemism within the distribution of Oswaldella species in the Southern Ocean, thereby testing previous hypotheses and proposing alternative scenarios for Antarctic evolution. Location Southern Ocean, Antarctic and sub-Antarctic waters of southern South America. Methods We prepared a database for the 31 currently known species of the Antarctic genus Oswaldella, which includes geographical locations gathered from published taxonomic studies as well as materials from museums and expeditions. A parsimony analysis of endemicity (PAE) was used to test hypotheses of distribution patterns. Results Four areas of endemism are hypothesized: southern…
Do small marinas drive habitat specific impacts? A case study from Mediterranean Sea.
2011
Many human activities add new structures to the marine landscape. Despite the fact that human structures cause some inevitable impacts, surprisingly little information exists on the effects of marina on natural marine assemblages. The aim of this paper is to assess habitat-specific response of benthic sessile organisms of rocky shores in relation to the presence of a small marina. Sampling was carried out at three coastal habitats (midshore, lowshore and subtidal) by means of visual censuses adopting an after-control-impact (ACI) experimental design. It appears that the marina affects the structure and composition of benthic communities of both the midshore and the lowshore. Little effect w…
Response of benthic foraminifera to heavy metal contamination in marine sediments (Sicilian coasts, Mediterranean sea)
2011
To examine the suitability of benthic foraminifera and their test deformations as bioindicators of pollution in coastal marine environments, we studied foraminifera and metal concentrations in 72 marine sediment samples, collected from the inner shelf along the Sicilian coast (Gulfs of Palermo and Termini) and on the south-eastern coast of Lampedusa Island. These areas are characterised by different environmental conditions. On the basis of pollution sources and foraminiferal assemblages, we recognised different zones in the Gulf of Palermo. The most polluted zones showed high metal concentrations, and low diversity of benthic foraminifera with species typical of stressed environments. By c…
Diversity of meiofauna in the lacustrine profundal zone: Bathymetric differences and influence of environmental factors
1993
The diversity and species richness of total meiofauna, Harpacticoida and Oligochaeta in relation to depth and other environmental variables were studied at nine stations and in two profundal depth zones in Lake Paijanne which includes both oligotrophic and eutrophicated or organically loaded areas.
Correspondence between regional delineations and spatial patterns in macroinvertebrate assemblages of boreal headwater streams
2002
AbstractGeographical stratification may provide a useful framework for stream management programs, yet most studies testing the utility of such stratifications have been conducted in temperate regions. We studied the correspondence between regional delineations (5 ecoregions, 11 subecoregions), environmental characteristics, and benthic macroinvertebrate assemblages in 156 boreal headwater streams in Finland, using a combination of principal components analysis, nonmetric multidimensional scaling, and discriminant function analysis (DFA). Both stream characteristics and macroinvertebrate assemblage structure showed a closer correspondence to ecoregions than to subecoregions, a pattern partl…