Search results for "streams"
showing 10 items of 83 documents
Changes in habitat structure, benthic invertebrate diversity, trout populations and ecosystem processes in restored forest streams: a boreal perspect…
2007
SUMMARY 1. Most Finnish streams were channelised during the 19th and 20th century to facilitate timber floating. By the late 1970s, extensive programmes were initiated to restore these degraded streams. The responses of fish populations to restoration have been little studied, however, and monitoring of other stream biota has been negligible. In this paper, we review results from a set of studies on the effects of stream restoration on habitat structure, brown trout populations, benthic macroinvertebrates and leaf retention. 2. In general, restoration greatly increased stream bed heterogeneity. The cover of mosses in channelised streams was close to that of unmodified reference sites, but a…
DEFINING MACROINVERTEBRATE ASSEMBLAGE TYPES OF HEADWATER STREAMS: IMPLICATIONS FOR BIOASSESSMENT AND CONSERVATION
2003
We used data from 235 boreal headwater streams in Finland to examine whether macroinvertebrate assemblages constitute clearly definable types, and how well biologically defined assemblage types can be predicted using environmental variables. Two- way indicator species analysis produced 10 assemblage types, which differed significantly from each other (multiresponse permutation procedure, MRPP). However, based on MRPP and nonmetric multidimensional scaling, there was wide variation among sites within each assemblage type, and high degrees of overlap among assemblage types. Such continuous variation was also evidenced by the low number of effective indicator taxa (indicator value method) for …
Does porewater or meltwater control tunnel valley genesis? Case studies from the Hirnantian of Morocco.
2015
18 pages; International audience; Several Ordovician tunnel valleys are exposed in the Moroccan Anti-Atlas Mountains, including the Alnif and the Foum Larjamme tunnel valleys, located 150 km away from each other. Sedimentological and deformational analyses of these two glacial troughs reveal that differing processes lead to their formations.The Alnif tunnel valley contains numerous deformation structures within sediments both below and above the main glacial erosion contact surface. Ball-structures and clastic dykes occur within preglacial sediments down to 35 m below glacial incisions while overlying glacial sediments contain fluted surfaces, clastic dykes, dewatering structures, folds and…
Joint Alignment and Modeling of Correlated Behavior Streams
2013
The Variable Time-Shift Hidden Markov Model (VTS- HMM) is proposed for learning and modeling pairs of cor- related streams. Unlike previous coupled models for time series, the VTS-HMM accounts for varying time shifts be- tween correlated events in pairs of streams having different properties. The VTS-HMM is learned on a set of pairs of unaligned streams and, thus, learning entails simultaneous estimation of the varying time shifts and of the parameters of the model. The formulation is demonstrated in the analysis of videos of dyadic social interactions between children and adults in the Multimodal Dyadic Behavior Dataset (MMDB). In dyadic social interactions, an agent starts an interaction …
Long-term recovery of stream habitat structure and benthic invertebrate communities from in-stream restoration
2002
Headwater streams channelized for water transport of timber in Finland are being restored to their pre-channelization state. The primary motivation is the enhancement of sport fisheries, but restoration probably has profound impacts also on other stream organisms. We assessed how such ‘‘single-goal’’ restorations affect benthic macroinvertebrate communities. We revisited the streams sampled by Laasonen et al. [Aquatic Conservation: Marine and Freshwater Ecosystems 8 (1998)] in the early 1990s when the streams had been recently restored. In 1997, the recovery period of these streams ranged from 4 to 8 years. Habitat structure among the stream types represented a distinct recovery gradient, w…
Enzyme-assisted extraction of anthocyanins and other phenolic compounds from blackcurrant (Ribes nigrum L.) press cake: From processing to bioactivit…
2022
The effects of commercial enzymes (pectinases, cellulases, beta-1-3-glucanases, and pectin lyases) on the recovery of anthocyanins and polyphenols from blackcurrant press cake were studied considering two solid:solvent ratios (1:10 and 1:4 w/v). β-glucanase enabled the recovery of the highest total phenolic content – 1142 mg/100 g, and the extraction of anthocyanins was similar using all enzymes (∼400 mg/100 g). The use of cellulases and pectinases enhanced the extraction of antioxidants (DPPH − 1080 mg/100 g; CUPRAC – 3697 mg/100 g). The freeze-dried extracts presented antioxidant potential (CUPRAC, DPPH), which was associated with their biological effects in different systems: antiviral a…
545. Un período fundamental para la climatología española: el “descubrimiento” de la circulación atmosférica en altitud, 1950-1980
2016
El período que transcurre entre los años 1950 y 1980 resulta decisivo para la consolidación de la climatología española. Los trabajos de una serie de geógrafos españoles (López Gómez, García Fernández, Gil Olcina, Burriel de Orueta, Albentosa Sánchez y Capel Molina) se convertirán en referencias básicas al presentar en nuestro país los avances sobre la circulación atmosférica en las capas altas de la troposfera que se desarrollan después de la 2a Guerra Mundial en Estados Unidos y otros países europeos. Este trabajo analiza el contexto científico en el que tiene lugar el “descubrimiento” de la circulación atmosférica en altitud por parte de la geografía española y su repercusión para la mej…
Evaluation of biological properties of extracts obtained from marine biomass assisted by pulsed electric fields (PEF) and pressurized liquid extracti…
2022
Teniendo en cuenta el gran interés por la biodiversidad, los recursos marinos representan una fuente importante de compuestos de alto valor añadido como proteínas y péptidos bioactivos, lípidos y ácido grados vitaminas, minerales y compuestos bioactivos, etc. Los residuos y subproductos del pescado como cabeza, vísceras y piel, entre otros, se descartan o no se utilizan de manera efectiva durante el procesamiento de los alimentos, lo que resulta en un gran desperdicio de recursos, sin embargo, son una gran fuente de compuestos con alto valor añadido y que pueden tener un potencial uso considerable en las industrias alimentaria, farmacéutica, cosmética y otras, existiendo, por lo tanto, un i…
Life in the ice lane: the winter ecology of stream salmonids
2007
Despite the common view that conditions in winter strongly influence survival and population size of fish, the ecology of salmonids has not been as extensively studied in winter as in other seasons. In this paper, we review the latest studies on salmonid winter survival, habitat use, movement and biotic interactions as they relate to the prevailing physical and habitat conditions in rivers and streams. The majority of research conducted on the winter ecology of salmonids has been carried out in small rivers and streams, where temperatures are above zero and where there is no ice. Investigations in large rivers, regulated and dredged rivers, and under conditions of different ice formations a…
Intercohort competition causes spatial segregation in brown trout in artificial streams
1999
When together in a flume, 13-cm LS (age-1) trout appeared to increase their activity and behaved more aggressively, whereas 10-cm LS (age-0) trout tended to move less and were rarely aggressive in the presence of the larger size class. Both size classes were less mobile and preferred lower water velocities in winter than in summer, and increased their use of instream cover in winter. When both size classes were present, only small trout decreased their use of low water velocities and cover. The results indicate that intercohort competition may cause spatial segregation among size groups of brown trout, especially in winter when trout attempt to minimize their maintenance costs.