Search results for "benthic"
showing 10 items of 350 documents
Dietary ontogeny and niche shift to piscivory in lacustrine brown trout Salmo trutta revealed by stomach content and stable isotope analyses
2012
The feeding ecology and ontogeny of a large size range of brown trout Salmo trutta in Lake Fyresvatnet, southern Norway, were examined by stomach content and stable isotope analyses. According to the stomach contents, the S. trutta changed their diet at c. 30 cm total length (L(T) ). The smaller size classes fed on benthic invertebrates and surface insects, whereas larger S. trutta (30 cm) fed mainly on whitefish Coregonus lavaretus. A similar, but more gradual shift to piscivory in the size range 25-30 cm was found when using the stable isotope mixing model SIAR to reveal dietary ontogeny. The δ¹³C isotopic signature confirmed that S. trutta independent of size predominantly relied upon be…
Trophic ecology of the swimming crab Polybius henslowii Leach, 1820 in Galician and Cantabrian Seas: Influences of natural variability and the Presti…
2008
9 pages, 9 figures, 2 tables.-- Printed version published Nov 15, 2008.
Catastrophic effects of sand mining on macroinvertebrates in a large shallow lake with implications for management
2019
Sand mining is a human activity that is increasing in inland waters and has profound effects on entire aquatic ecosystems. However, current knowledge of the effects of sand mining on freshwater lake ecosystems remains limited, especially for biotic communities. Here, we investigated the responses of macroinvertebrates to indiscriminate sand mining in a large shallow lake of China. Our results indicated that sand mining significantly increased the content of suspended particulate matter, total nitrogen, total phosphorus and chlorophyll a in the water column both in the sand mining area and the area adjacent to the dredging activities. While there was significantly lower total nitrogen and th…
Toxicity of fullerene (C60) to sediment-dwelling invertebrate Chironomus riparius larvae
2011
An environmentally realistic method to test fullerene (C(60) ) toxicity to the benthic organism Chironomus riparius was created by allowing suspended fullerenes to settle down, making a layer on top of the sediment. To test the hypothesis that higher food concentrations will reduce toxic responses, two food concentrations were tested (0.5 and 0.8% Urtica sp.) in sediment containing fullerene masses of 0.36 to 0.55 mg/cm(2) using a 10-d chronic test. In the 0.5% food level treatments, there were significant differences in all growth-related endpoints compared with controls. Fewer effects were observed for the higher food treatment. Fullerene agglomerates were observed by electron microscopy …
Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia)
2016
International audience; This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages.In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be consider…
Long-term zoobenthos variability in the Gulf of Riga in relation to climate variability
2001
Abstract Macrozoobenthos data were collected three times a year from 1979 to 1996 in the Gulf of Riga, Eastern Baltic Sea. Interannual variability of the abundance and biomass of benthic fauna at coastal and offshore areas was related to climate variability using a multivariate regression model. The results suggest that the interannual variability of macrozoobenthos biomass at the offshore station in spring is controlled by the climate variability during winter-time. No correlations to large-scale climate pattern have been detected for other seasons and for the coastal region. An analysis of river runoff, nitrogen, and phosphorus data of the River Daugava indicates that the anthropogenic in…
Species of Acryptolaria Norman, 1875 (Cnidaria: Hydrozoa) collected by US Antarctic and sub-Antarctic expeditions.
2020
Acryptolaria is a worldwide genus of deep-water benthic hydroids. The genus has relatively high species diversity, with 36 species described so far, yet most of them have been reported only occasionally. As a result, scientific knowledge of their ecology and distribution is scarce. Here I present the results of the study of species of Acryptolaria collected during several Antarctic and sub-Antarctic expeditions under the United States Antarctic Research Program between 1958 and 1986. Eight species were found in the collection (plus one determined to the genus level), with A. operculata having the highest occurrence. Acryptolaria flabellum is reported for the second time; the study also repr…
Southern Ocean areas of endemism: a reanalysis using benthic hydroids (Cnidaria, Hydrozoa)
2013
The biogeographic history of the Southern Ocean (SO) fauna is complex and poorly studied, especially the areas of endemism. We reanalyzed the data of Marques & Peña Cantero (2010), along with other geographical records of endemic benthic hydroids below 45°S. A Parsimony Analysis of Endemicity (PAE) based on 5° latitude by 5° longitude matrix with 61 species resulted in eight areas of endemism. We discuss these results in the context of different hypotheses of the evolution of the SO fauna and previously proposed biogeography patterns.
<strong>Review of some little-known benthic hydroids (Cnidaria, Hydrozoa) from the Southern Ocean</strong>
2015
A number of benthic hydroid species inhabiting the Southern Ocean are insufficiently characterized. A revision of eight little-known Antarctic species of the order Anthoathecata was made, based on the study of type material. Some of the species have not been recorded since their original description a century ago. Four species (Bimeria corynopsis, Bougainvillia macloviana, ?Koellikerina belgicae and Rhizorhagium antarcticum) belong to the family Bougainvilliidae, two species (Hydractinia angusta and H. dendritica) to the family Hydractiniidae, Perarella clavata to the family Cytaeididae and, finally, Rhysia halecii to the family Rhysiidae. For each species a list of synonyms, a description,…
The effect of automated taxa identification errors on biological indices
2017
In benthic macroinvertebrate biomonitoring systems, the target is to determine the status of ecosystems based on several biological indices. To increase cost-efficiency, computer-based taxa identification for image data has recently been developed. Taxa identification errors can, however, have strong effects on the indices and thus on the determination of the ecological status. In order to shift the biomonitoring process towards automated expert systems, we need a clear understanding on the bias caused by automation. In this paper, we examine eleven classification methods in the case of macroinvertebrate image data and show how their classification errors propagate into different biological…