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Water Habitats (water + habitat)
Selected AbstractsHabitat use and foraging success of 0+ pike (Esox lucius L.) in experimental ponds related to prey fish, water transparency and light intensityECOLOGY OF FRESHWATER FISH, Issue 2 2002C. Skov Abstract ,,,This study investigated the habitat use of 0+ pike (9,17 cm) in relation to two different water transparency regimes (clear water/chlorophyll water), two different light regimes (day/night) and the presence/absence of prey using 16 m2 experimental ponds. Pike could freely choose between two structured habitats (a simple structured and a complex structured), an interface habitat (between the structured habitats and open water) and an open water habitat. Foraging success of the pike in relation to water transparency was investigated by comparing mean condition (Fultons K) of the pike as well as the number of surviving prey fish. Habitat use was influenced by the presence/absence of prey and varied between waters with different transparency. The presence of prey intensified the use of structural habitats of 0+ pike in both clear and chlorophyll waters. A preference for complex habitats was found in clear water and was presumably related to foraging. The pike in chlorophyll water, in contrast, appeared more evenly distributed among all habitats, as illustrated by a more intensive use of open water in chlorophyll water compared to the clear water. No detectable impact of water transparency on the foraging success of 0+ pike was found. [source] REPLICATED EVOLUTION OF INTEGRATED PLASTIC RESPONSES DURING EARLY ADAPTIVE DIVERGENCEEVOLUTION, Issue 4 2006Kevin J. Parsons Abstract Colonization of a novel environment is expected to result in adaptive divergence from the ancestral population when selection favors a new phenotypic optimum. Local adaptation in the new environment occurs through the accumulation and integration of character states that positively affect fitness. The role played by plastic traits in adaptation to a novel environment has generally been ignored, except for variable environments. We propose that if conditions in a relatively stable but novel environment induce phenotypically plastic responses in many traits, and if genetic variation exists in the form of those responses, then selection may initially favor the accumulation and integration of functionally useful plastic responses. Early divergence between ancestral and colonist forms will then occur with respect to their plastic responses across the gradient bounded by ancestral and novel environmental conditions. To test this, we compared the magnitude, integration, and pattern of plastic character responses in external body form induced by shallow versus open water conditions between two sunfish ecomorphs that coexist in four postglacial lakes. The novel sunfish ecomorph is present in the deeper open water habitat, whereas the ancestral ecomorph inhabits the shallow waters along the lake margin. Plastic responses by open water ecomorphs were more correlated than those of their local shallow water ecomorph in two of the populations, whereas equal levels of correlated plastic character responses occurred between ecomorphs in the other two populations. Small but persistent differences occurred between ecomorph pairs in the pattern of their character responses, suggesting a recent divergence. Open water ecomorphs shared some similarities in the covariance among plastic responses to rearing environment. Replication in the form of correlated plastic responses among populations of open water ecomorphs suggests that plastic character states may evolve under selection. Variation between ecomorphs and among lake populations in the covariance of plastic responses suggests the presence of genetic variation in plastic character responses. In three populations, open water ecomorphs also exhibited larger plastic responses to the environmental gradient than the local shallow water ecomorph. This could account for the greater integration of plastic responses in open water ecomorphs in two of the populations. This suggests that the plastic responses of local sunfish ecomorphs can diverge through changes in the magnitude and coordination of plastic responses. Although these results require further investigation, they suggest that early adaptive evolution in a novel environment can include changes to plastic character states. The genetic assimilation of coordinated plastic responses could result in the further, and possibly rapid, divergence of such populations and could also account for the evolution of genes of major effect that contribute to suites of phenotypic differences between divergent populations. [source] Effect of light and predator abundance on the habitat choice of plant-attached zooplanktonFRESHWATER BIOLOGY, Issue 3 2007LEENA NURMINEN Summary 1. The diurnal variations in the habitat choice of the periodically plant-attached cladoceran Sida crystallina together with light environment and predator abundance were studied. 2. The density of S. crystallina attached to floating leaves of Nuphar lutea increased between 18:00 and 20:00 hours, when light intensity underneath the leaves was temporarily increased, and decreased again when light intensity declined. A proportion of S. crystallina remained in the swimming mode underneath the leaves even during daylight, indicating that the water column sheltered by the leaves is safer than the open water. 3. In the water adjacent to the leaves, the density of S. crystallina increased steeply in the dark. The increase was not accompanied by a decrease in S. crystallina attached to plant leaves, indicating that the nocturnal increment in the open water density of S. crystallina was due to migration from daytime refuges other than floating leaves. 4. Sida crystallina was most intensively consumed by perch (Perca fluviatilis). Predation threat by fish had weaker effects on the density of S. crystallina attached to plant leaves than on cladocerans in the adjacent water. Cladocerans underneath floating plant leaves, whether attached or not, are probably less vulnerable to fish predation than those outside the leaf cover. 5. The results suggested that light intensity is the proximate factor regulating the attachment of zooplankton to the lower surfaces of floating macrophyte leaves. Light intensity has a positive effect on the density of S. crystallina attached to the floating leaves and a negative effect on density in the water. Predation threat by fish has a strong effect on the migration of zooplankters into the open water habitat. [source] Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Jodi Holm Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source] Regulation of virulence and antibiotic resistance by two-component regulatory systems in Pseudomonas aeruginosaFEMS MICROBIOLOGY REVIEWS, Issue 2 2009W. James Gooderham Abstract The Gram-negative opportunistic pathogen Pseudomonas aeruginosa ubiquitously inhabits soil and water habitats and also causes serious, often antibiotic resistant, infections in immunocompromised patients (e.g. cystic fibrosis). This versatility is mediated in part by a large repertoire of two-component regulatory systems that appear instrumental in the regulation of both virulence processes and resistance to antimicrobials. Major two-component regulatory system proteins demonstrated to regulate these diverse processes include PhoP,PhoQ, GacA,GacS, RetS, LadS, and AlgR, among others. Here, we summarize the current body of knowledge of these and other two-component systems that provides insight into the complex regulation of virulence and resistance in P. aeruginosa. [source] The use of indicator taxa as representatives of communities in bioassessmentFRESHWATER BIOLOGY, Issue 8 2005R. C. NIJBOER Summary 1. Sampling and processing of benthic macroinvertebrate samples is time consuming and expensive. Although a number of cost-cutting options exist, a frequently asked question is how representative a subset of data is of the whole community, in particular in areas where habitat diversity is high (like Dutch surface water habitats). 2. Weighted averaging was used to reassign 650 samples to a typology of 40 community types, testing the representativeness of different subsets of data: (i) four different types of data (presence/absence, raw, 2log- and ln-transformed abundance), (ii) three subsets of ,indicator' taxa (taxa with indicator weights 4,12, 7,12, and 10,12) and (iii) single taxonomic groups (n = 14) by determining the classification error. 3. 2log- and ln-transformed abundances resulted in the lowest classification error, whilst the use of qualitative data resulted in a reduction of 10% of the samples assigned to their original community type compared to the use of ln-transformed abundance data. 4. Samples from community types with a high number of unique indicator taxa had the lowest classification error, and classification error increased as similarity among community types increased. Using a subset of indicator taxa resulted in a maximum increase of the classification error of 15% when only taxa with an indicator weight 10,12 were included (error = 49.1%). 5. Use of single taxonomic groups resulted in high classification error, the lowest classification error was found using Trichoptera (68%), and was related to the frequency of the taxonomic group among samples and the indicator weights of the taxa. 6. Our findings that the use of qualitative data, subsets of indicator taxa or single taxonomic groups resulted in high classification error implies low taxonomic redundancy, and supports the use of all taxa in characterising a macroinvertebrate community, in particular in areas where habitat diversity is high. [source] Geographical history of the central-western Pacific black fly subgenus Inseliellum (Diptera: Simuliidae: Simulium) based on a reconstructed phylogeny of the species, hot-spot archipelagoes and hydrological considerationsJOURNAL OF BIOGEOGRAPHY, Issue 9 2001Douglas A. Craig Aim With six new species of subgenus Inseliellum Rubtsov recently described, a revised reconstructed phylogeny based on morphology is required. Geological history of islands where Inseliellum occurs, plus a cladistic analysis and hydrological considerations, provide the basis for a reconstructed geographical history of the species. Location Inseliellum is widely distributed and occurs in Micronesia, Cook Islands and Polynesia. A single specimen is known from Tonga Islands. Methods Maximum parsimony criteria using PAUP*, plus cytological information, were used to arrive at a preferred phylogenic reconstruction. Island ages of the hot spot archipelagoes involved are well known. The phylogeny was then compared with the palaeogeology. Information on evolution of running water habitats as islands age was incorporated into the biogeography. Results Cladistic analysis of forty of the forty-eight known Inseliellum species with Simulium (Nevermannia) neornatipes Dumbleton from New Caledonia and S. (Hebridosimulium) laciniatum Edwards from Fiji as outgroups, shows basal species and clades to be on widely separated older islands. In the Society Islands basal species are widely spread. Derived species, with morphological adaptations to deal with specialized habitats, are on younger islands (e.g. Tahiti), where a major species radiation has taken place. The reconstructed phylogeny indicates dispersal back to older islands, with minor subsequent species radiation. Main conclusions Palaeogeological evidence provides a basis for postulating that Inseliellum entered the western Pacific area some 20 Ma, with the possibility that it rafted eastwards on proto-Tonga Islands to the edge of southern-central Pacific. Older Cook Islands were present at that time. Movement into the Marquesas Islands was not earlier than 6 Ma and into the Society Islands perhaps 8,10 Ma. Basal species with generalized habitat requirements would have found suitable habitats (inferred from hydrological postulates) on leaves in the original, small shaded streams. With erosion and valley development, in particular on Tahiti, species radiated into specialized habitats such as cascades. Rich seston and high velocity probably drove reduction of filtering fans in some clades. With collapse of the caldera and formation of large rivers at c. 0.9 Ma, S. exasperans Craig and S. tahitiense Edwards adapted to deep, swiftly flowing water, all indicative that specialized habitat availability drove species radiation in Inseliellum. In the Society Islands, dispersal of derived species back to the oldest western islands was not possible because erosion has removed suitable habitats. [source] Morphological specializations of baleen whales associated with hydrodynamic performance and ecological nicheJOURNAL OF MORPHOLOGY, Issue 11 2006Becky L. Woodward Abstract Feeding behavior, prey type, and habitat appear to be associated with the morphological design of body, fluke, and flippers in baleen whales. Morphometric data from whaling records and recent stranding events were compiled, and morphometric parameters describing the body length, and fluke and flipper dimensions for an "average" blue whale Balaenoptera musculus, humpback whale Megaptera novaeangliae, gray whale Eschrichtius robustus, and right whale Eubalaena glacialis were determined. Body mass, body volume, body surface area, and fluke and flipper surface areas were estimated. The resultant morphological configurations lent themselves to the following classifications based on hydrodynamic principles: fast cruiser, slow cruiser, fast maneuverer, and slow maneuverer. Blue whales have highly streamlined bodies with small, high aspect ratio flippers and flukes for fast efficient cruising in the open ocean. On the other hand, the rotund right whale has large, high aspect ratio flukes for efficient slow speed cruising that is optimal for their continuous filter feeding technique. Humpbacks have large, high aspect ratio flippers and a large, low aspect ratio tail for quick acceleration and high-speed maneuvering which would help them catch their elusive prey, while gray whales have large, low aspect ratio flippers and flukes for enhanced low-speed maneuvering in complex coastal water habitats. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source] A seasonal survey of surface water habitats within the River Spey basin, Scotland: major nutrient propertiesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2007B.O.L. Demars Abstract 1.Current monitoring strategies of governmental organizations tend to be focused on relatively large flowing and standing waters, and until recently those polluted by point sources. Consequently areas of high conservation interest tend to be understudied, and defining reference conditions, as required by current legislation, is difficult to achieve. 2.In order to address this imbalance, water samples have been collected and analysed once in each of four seasons during 2003 from 72 locations within a 100 km2 area of the oligotrophic River Spey catchment in NE Scotland. The sampling design included examples of running water (headwater streams and the main rivers) and standing water (lochs, lochans, pools, ditches, backwaters, bogs). Altitude ranged from 220 to 980 m and incorporated a climatic regime from cool temperate to sub-alpine. Each sampling campaign targeted low-flow conditions to evaluate steady-state nutrient concentrations. 3.Concentrations of the major soluble nutrients nitrogen and phosphorus demonstrated high spatial and temporal variability, with soluble organic and molybdate unreactive forms generally being dominant. Concentrations of ammonium-N, nitrate-N and soluble reactive phosphorus were extremely small, with 50% of samples falling below 8, 5 and 1 µg L,1, respectively, during spring and summer. 4.Sampling sites were grouped either by water-body type or by the properties of their immediate biophysical zone. Together these two groupings explained 33,38% of the variance in water chemistry. Certain changes were detectable across most habitats and biophysical zones. 5.A decline in the concentration of nitrate that occurred in reaches downstream from certain headwater streams draining the mountain areas indicated the potential for its within-stream utilization. Inorganic N dynamics differed between small streams and large rivers. 6.Landscape-scale patterns were recorded in spring and summer nutrient availability with inorganic N and P thresholds (arbitrarily defined) of 10 and 1 µg L,1, respectively. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of seasonal variation in salinity on a population of Enochrus bicolor Fabricius 1792 (Coleoptera: Hydrophilidae) and implications for other beetles of conservation interestAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2003M.T. Greenwood Abstract 1.A population of Enochrus bicolor (Fabricius) was monitored over a 4-year period (March 1997,March 2001) from a coastal brackish pool in S.E. Essex. This water beetle, together with Ochthebius marinus (Payk.), O. viridis Peyrhiff, O. punctatus Steph., Hygrotus parallelogrammus (Ahrens), Berosus affinis Brulle, Agabus conspersus, (Marsham), Rhantus frontalis (Marsham), R. suturalis (MacLeay), Paracymus aeneus (Germar), and Haliplus apicalis Thompson, are all taxa of conservation interest. 2.Enochrus bicolor was present in most months, with greatest adult abundances being recorded in August and September each year. 3.During the study period salinity values ranged from 4.7 ppt (parts per thousand) to 62.6 ppt. 4.Correlation analysis and the development of regression models indicated that the highest abundances of E. bicolor coincided with maximum water temperature in the late summer,early autumn. However, when the natural seasonal signal was removed by standardizing the series, a relatively weak association with the relative abundance of E. bicolor and conductivity was observed. 5.The conservation of E. bicolor and other organisms associated with brackish water habitats subject to irregular marine inundation is considered. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||