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Deposit Feeders (deposit + feeder)
Selected AbstractsDigestive bioavailability to a deposit feeder (Arenicola marina) of polycyclic aromatic hydrocarbons associated with anthropogenic particles,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2004Ian M. Voparil Abstract Marine sediments around urban areas serve as catch basins for anthropogenic particles containing polycyclic aromatic hydrocarbons (PAHs). Using incubations with gut fluids extracted from a deposit-feeding polychaete (Arenicola marina), we determined the digestive bioavailability of PAHs from fly ashes, coal dusts, diesel soots, tire tread materials, and urban particulates. We found that gut fluids solubilize significant concentrations of PAHs from two tire treads, two diesel soots, and the urban particulates. However, PAHs in fly ashes and coal dusts were not available to the digestive agents in gut fluid. Potential digestive exposure to PAHs is much greater than that predicted to be available from these materials using equilibrium partitioning theory (EqP). Amending an already-contaminated sediment with fly ash decreased phenanthrene solubilization by gut fluid. In contrast, addition of tire tread to the sediment resulted in increased solubilization of four PAHs by gut fluid. Therefore, addition of certain types of anthropogenic particles to sediments may result in an increase in bioavailable PAHs rather than a net decrease, as predicted by EqP. Difficulty in predicting the amount of change due to amendment may be due to interactions occurring among the mixture of compounds solubilized by gut fluid. [source] Biological and ecological traits of benthic freshwater macroinvertebrates: relationships and definition of groups with similar traitsFRESHWATER BIOLOGY, Issue 2 2000Philippe Usseglio-Polatera Summary 1Relating species traits to habitat characteristics can provide important insights into the structure and functioning of stream communities. However, trade-offs among species traits make it difficult to predict accurately the functional diversity of freshwater communities. Many authors have pointed to the value of working with groups of organisms as similar as possible in terms of relationships among traits and have called for definition of groups of organisms with similar suites of attributes. 2We used multivariate analyses to examine separately the relationships among 11 biological traits and among 11 ecological traits of 472 benthic macroinvertebrate taxa (mainly genera). The main objective was to demonstrate (1) potential trade-offs among traits; (2) the importance of the different traits to separate systematic units or functional groupings; and (3) uniform functional groups of taxa that should allow a more effective use of macroinvertebrate biological and ecological traits. 3We defined eight groups and 15 subgroups according to a biological trait ordination which highlighted size (large to small), reproductive traits (K to r strategists), food (animal to plant material) and feeding habits (predator to scraper and/or deposit feeder) as ,significant' factors determining the ordination of taxa. This ordination partly preserved phylogenetic relationships among groups. 4Seven ecological groups and 13 ecological subgroups included organisms with combinations of traits which should be successively more adequate in habitats from the main channel to temporary waters, and from the crenon to the potamic sections of rivers, and to systems situated outside the river floodplain. These gradients corresponded to a gradual shift from (1) rheophilic organisms that lived in the main channel of cold oligotrophic mountain streams to (2) animals that preferred eutrophic habitats of still or temporary waters in lowlands. The groups with similar ecological traits had a more diverse systematic structure than those with similar biological traits. 5Monitoring and assessment tools for the management of water resources are generally more effective if they are based on a clear understanding of the mechanisms that lead to the presence or absence of species groups in the environment. We believe that groups with similar relationships among their species traits may be useful in developing tools that measure the functional diversity of communities. [source] Ecospace utilization in early Phanerozoic deep-marine environments: deep bioturbation in the Blakely Sandstone (Middle Ordovician), Arkansas, USALETHAIA, Issue 2 2003PATRICK J. ORR Ichnofabric analysis of alternating light and dark-coloured mudstone layers in the Blakely Sandstone (Middle Ordovician) at Crystal Springs Landing, Lake Ouachita (west of Hot Springs, western Arkansas, USA) reveals two equilibrium palaeoichnocoenoses. The first was emplaced under variable, but low, oxygen levels during deposition of the dark-coloured layers; small diameter transition layer burrows overprint a mixed layer ichnofabric. The transition layer infauna was tiered with abundant Chondrites representing the deeper of two shallow tiers. Light-coloured layers accumulated during prolonged intervals in which the sediments were oxygenated to a greater extent and depth. Preservation of a mixed layer ichnofabric within them is the result of limited, but deep (up to at least 400 mm), reworking subsequently in the transition layer by an equilibrium community. These transition layer trace fossils are not tiered. If representative of oxygenated sediment columns in Ordovician deep-marine environments, an extensive volume of infaunal ecospace was colonized (in this case by deposit feeders); its more efficient use subsequently, including vertical partitioning of the infaunal community into specific environmental niches (tiering), could have accommodated increases in diversity and community complexity. Changes over time in the maximum depth to which sediments were bioturbated, alone, would therefore be a poor measure of the extent of ecospace utilization. [source] Another diet of worms: the applicability of polychaete feeding guilds as a useful conceptual framework and biological variableMARINE ECOLOGY, Issue 3-4 2005Paulo Roberto Pagliosa Abstract A fundamental question in guild studies is how to separate species into guilds. In a seminal manuscript, Fauchald & Jumars [Oceanography and Marine Biology Annual Review17 (1979) 193] summarized polychaete feeding biology and proposed a conceptual framework to test hypotheses on the sympatric occurrence of congeners with limited morphological differentiation. Twenty-six years after this publication, few studies have tested the validity and practical functioning of this scheme of polychaete feeding guilds and then only using part of the classification. The objective of the present study was to analyze the applicability of polychaete feeding guilds to ecological and environment assessments. Two data sets from Santa Catarina Island Bay, southern Brazil, were used. The first data set deals with spatial distribution of natural polychaete assemblages along the bay. The second data set treats fauna in urbanized versus relatively pristine mangroves. Multivariate analysis showed similar patterns in sample groups formed using guilds or densities and composition data. The role of feeding guilds in benthic systems was assessed through comparison with environmental variables. The polychaete assemblage from the Bay was related to sediment type. Motile and discretely motile carnivores and herbivores with jawed probosces matched coarse sands; surface deposit feeders and filter feeders were found in fine sands; and surface and subsurface deposit feeders and carnivores, all with soft probosces matched silt and clay sediments. The data analyses in mangroves showed surface deposit feeders and filter feeders in undisturbed sites and omnivorous species in disturbed ones. The polychaete feeding guilds appear relevant to assembly rules based on resource availability, to resource partitioning and to interspecific competition. [source] Macrofauna Communities in the Eastern Mediterranean Deep SeaMARINE ECOLOGY, Issue 3 2003Ingrid Kröncke Abstract., During two expeditions with RV ,Meteor' in summer 1993 and winter 1997/98 the structural and functional diversity of the benthic system of the highly oligotrophic eastern Mediterranean deep sea was investigated. The macrofauna communities were dominated by polychaetes even at the deepest stations. The fauna at shallow stations was dominated by surface deposit feeders, whereas subsurface deposit feeders and predators generally increased with depth. A high percentage of suspension-feeding Porifera was found in the Levantine Basin. Mean abundance and number of taxa of both expeditions were significantly correlated to depth and distance to the nearest coast as well as to the total organic carbon (TOC) content in sediments. Numbers of taxa and abundance decreased generally with depth, although lowest numbers were not found at the deepest stations but in the extremely oligotrophic Levantine and Ierapetra Basin. Biomass measured during the second cruise was extremely low in the Ierapetra Basin and comparable to other extreme oligotrophic seas. The significant correlations found for TOC contents and macrofauna with distance to coast during both expeditions apparently reflect the role of hydrographically governed transport of organic matter produced in coastal regions into greater and extreme depths of the Mediterranean Sea. Seasonal differences in macrofauna communities due to seasonal differences in food supply were not found. However, recent large-scale hydrographic changes (Eastern Mediterranean Transient, EMT) might change the oligotrophy and, thus, the structure of the benthic communities in the Eastern Mediterranean deep sea. [source] Dynamics of the Polychaetes Desdemona ornata and Perinereis cultrifera and Their Resources of Food in a Mediterranean MudflatMARINE ECOLOGY, Issue 4 2002Francesca Rossi Abstract. Availability of food in the sediment can play an important role in determining the dynamics of deposit feeders. Generally the abundance of deposit feeders during winter and spring is related to an increase in the nutritive value of the sediment due to the concurrent microalgal peaks. This work investigated, in 1998, the seasonal variability patterns in the nutritive value of the sediment and in the abundance of two polychaetes, Desdemona ornata (Sabellidae: Fabriicinae) and Perinereis cultrifera (Nereididae), that probably feed on benthic microalgae. Previously, in 1997, these two species were abundant in winter and spring. During that winter, the amount of chlorophyll a in the sediment was quite variable due to grazing activities. Three manipulative field experiments were carried out in winter and spring (January, March and April 1998) to test the hypothesis that increasing the amount of chlorophyll a increases the nutritional value of the sediment and the abundance of Perinereis cultrifera and Desdemona ornata. The results indicated that the patterns of variability for these species and for chlorophyll a were similar to those observed in 1997. In plots where microalgal growth was stimulated experimentally, Perinereis cultrifera increased in January and Desdemona ornata increased in January and March. The role of food in regulating the abundances of Perinereis cultrifera and Desdemona ornata is discussed. [source] | ||||||||||