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Shallow Areas (shallow + area)
Selected AbstractsThe Anatomy of the Gastrointestinal Tract of the African Lungfish, Protopterus annectensTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2010José M. Icardo Abstract The gastrointestinal tract of the African lungfish Protopterus annectens is a composite, which includes the gut, the spleen, and the pancreas. The gut is formed by a short oesophagus, a longitudinal stomach, a pyloric valve, a spiraling intestine, and a cloaca. Coiling of the intestine begins dorsally below the pylorus, winding down to form six complete turns before ending into the cloaca. A reticular tissue of undisclosed nature accompanies the winding of the intestinal mucosa. The spleen is located along the right side of the stomach, overlapping the cranial end of the pancreas. The pancreas occupies the shallow area, which indicates on the gut dorsal side the beginning of the intestine coiling. In addition, up to 25 lymphatic-like nodes accompany the inner border of the spiral valve. The mesenteric artery forms a long axis for the intestine. All the components of the gastrointestinal tract are attached to each other by connective sheaths, and are wrapped by connective tissue, and by the serosa externally. We believe that several previous observations have been misinterpreted and that the anatomy of the lungfish gut is more similar among all the three lungfish genera than previously thought. Curiously, the gross anatomical organization is not modified during aestivation. We hypothesize that the absence of function is accompanied by structural modifications of the epithelium, and are currently investigating this possibility. Anat Rec 293:1146,1154, 2010. © 2010 Wiley-Liss, Inc. [source] Stream habitat use and diet of juvenile (0+) brown trout and grayling in sympatryECOLOGY OF FRESHWATER FISH, Issue 4 2000E. Degerman Abstract , Electrofishing survey data and experiments carried out in a semi-natural stream were used to test the hypothesis that interactions between underyearling (0+) trout and grayling during their first summer affect habitat use and diet. The survey data revealed a general difference in habitat use, with 0+ grayling being more common than 0+ trout in large streams and deeper sections. It was also found that in the presence of trout, finer substrate and shallower sections were utilised more by grayling. Field experiments were carried out with three treatments; trout alone, grayling alone and the two species together. In both the July and September experiments grayling tended to occupy deeper sections than trout. Trout abundance was higher in shallow areas in sympatry, while no such difference was found in allopatry. The rate of disappearance of grayling from the study sections was significantly higher in sympatry in July, while no difference was found in September. In July the size difference between species and the degree of dietary overlap were small and non-significant, respectively, indicating that the two species were strongly competing., [source] Biocompatibility of Lotus-type Stainless Steel and Titanium in Alveolar BoneADVANCED ENGINEERING MATERIALS, Issue 9 2006Y. Higuchi Abstract Lotus-type porous stainless steel (SUS304L) and porous titanium were fabricated by unidirectional solidification in a mixture gas of hydrogen and argon. The porous metals which were cut into 5,mm cubes (non-dehydrogenated) and 3.4,mm,,×,5,mm cylinders (dehydrogenated) were implanted into the canine mandible alveolar bone for two, four and eight weeks for animal experiments. The changes in the tissues were observed using SEM. For porous stainless steel (cylindrical; dehydrogenated) new formation of bones was observed around the sample in two weeks without any sign of bony ingrowth into the pores. The osteogenesis was found in shallow areas in the pores in four weeks and deep in the pores in eight weeks. Porous titanium, on the other hand, showed deep ingrowth of new bones in four weeks. Our observations allowed us to expect application of the porous metals as biomaterials. They maintain mechanical strength and are lighter in weight so that it is expected to be applied for dental implants and core materials of artificial bones. [source] Influence of water flow velocity, water depth and colony distance on distribution and foraging patterns of terns in the Wadden SeaFISHERIES OCEANOGRAPHY, Issue 3 2009PHILIPP SCHWEMMER Abstract Surface-feeding seabirds, such as Common (Sterna hirundo) and Arctic Terns (Sterna paradisaea) in the German Wadden Sea, are dependent on biological and physical processes that affect prey availability close to the water surface. We proposed the following four hypotheses: (i) relationships should exist between high water flow velocity and foraging activity of terns, as turbulence should enhance prey availability at the surface; (ii) the areas of highest foraging success should be located within areas of low water depth, due to enhanced biological productivity; (iii) as terns are known to have small foraging radii, the location of their breeding grounds should be related to the location of their foraging grounds; (iv) terns should forage intensely in river estuaries, as these should hold ample food supplies. The time between terns leaving the colony and their first foraging attempt differed significantly among different tidal stages: the time was shortest during flood and ebb tides (i.e., highest water flow velocities). Modelling of a long-term data set revealed the highest probability of foraging activity in conditions of high water currents, in both shallow areas and in areas of around 15,20 m depth. Foraging activity was negatively correlated with distance from colony. The distance to the closest estuary had no significant effect on foraging behaviour. Our findings emphasize the physical,biological coupling in the Wadden Sea and highlight the overall importance of small-scale physical processes in directly influencing prey availability for surface-feeding seabirds. [source] Submerged macrophytes as indicators of the ecological quality of lakesFRESHWATER BIOLOGY, Issue 4 2010MARTIN SØNDERGAARD Summary 1. We analysed submerged macrophyte communities from 300 Danish lakes to determine the efficacy of different species, maximum colonisation depth (Cmax) of plants as well as coverage and plant volume inhabited (PVI) as indicators of eutrophication. 2. Most species occurred at a wide range of phosphorus and chlorophyll a (Chla) concentrations, but some species of isoetids (Lobelia, Isoëtes) and Potamogeton (Potamogeton gramineus, Potamogeton alpinus and Potamogeton filiformis) were mainly found at low nutrient concentrations and hence may be considered as indicators of nutrient poor conditions. However, species typically found in nutrient-rich conditions, such as Elodea canadensis and Potamogeton pectinatus, were also found at total phosphorus (TP) <0.02 mg P L,1 and Chla <5 ,g L,1 and therefore cannot be considered as reliable indicators of eutrophic conditions. 3. Submerged macrophyte coverage, PVI and the Cmax were negatively correlated with TP and Chla. However, variability among lakes was high and no clear thresholds were observed. At TP between 0.03 and 0.07 mg P L,1 plant coverage in shallow lakes ranged from nearly 0 to 100%, whilst at concentrations between 0.10 and 0.20 mg P L,1 only 29% of the lakes had coverage >10%. Cmax was found to be a useful indicator only in deep lakes with unvegetated areas in the deeper part, whereas the use of coverage was restricted to shallow lakes or shallow areas of deep lakes. 4. Overall, submerged macrophytes responded clearly to eutrophication, but the metrics investigated here showed no well-defined thresholds. We developed a simple index based on species richness, presence of indicator species, coverage and Cmax, which might be used to track major changes in macrophyte communities and for lake classification. [source] Soil water content and yield variability in vineyards of Mediterranean northeastern Spain affected by mechanization and climate variabilityHYDROLOGICAL PROCESSES, Issue 11 2006M. C. Ramos Abstract The objective of this paper was to analyse the combined influence of the Mediterranean climate variability (particularly the irregular rainfall distribution throughout the year) and the land transformations carried out in vineyards of northeastern Spain on soil water content evolution and its influence on grape production. The study was carried out in a commercial vineyard located in the Anoia,Alt Penedès region (Barcelona province, northeastern Spain), which was prepared for mechanization with important land transformations. Two plots were selected for the study: one with low degree of transformation of the soil profile, representing a non-disturbed situation, and the second one in which more than 3 m were cut in the upper part of the plot and filled in the lower part, representing the disturbed situation. Soil water content was evaluated at three positions along the slope in each plot and at three depths (0,20, 20,40, 40,60 cm) during the period 1999,2001, years with different rainfall characteristics, including extreme events and long dry periods. Rainfall was recorded in the experimental field using a pluviometer linked to a data-logger. Runoff rates and yield were evaluated at the same positions. For the same annual rainfall, the season of the year in which rainfall is recorded and its intensity are critical for water availability for crops. Soil water content varies within the plot and is related to the soil characteristics existing at the different positions of the landscape. The differences in soil depth created by soil movements in the field mechanization give rise to significant yield reductions (up to 50%) between deeper and shallow areas. In addition, for the same annual rainfall, water availability for crops depends on its distribution over the year, particularly in soils with low water-storage capacity. The yield was strongly affected in years with dry or very dry winters. Copyright © 2005 John Wiley & Sons, Ltd. [source] Condition of Salaria pavo in the Mar Menor coastal lagoon (SE Iberian Peninsula): potential influence of environmental variables on juvenilesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2006D. Verdiell-Cubedo Summary The relationship at the local level between fish condition and environmental variables was investigated in Salaria pavo (peacock blenny) juveniles. The relationships between fish condition and 18 environmental variables of shallow areas of the lagoon relating to intra- and interspecific fish interactions, water quality and habitat structure, were analysed. The study revealed that water depth and S. pavo biomass (both related to intraspecific fish interactions) were the ecological variables accounting for most of the variation in the condition of S. pavo juveniles, in this case a negative effect. In this way, the condition of S. pavo juvenile populations may be a good indicator of fish density interactions. [source] Length,weight relationships for 22 fish species of the Mar Menor coastal lagoon (western Mediterranean Sea)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2006D. Verdiell-Cubedo Summary Length,weight relationships were estimated for 22 species of the Mar Menor coastal lagoon (south-eastern Spain): Lipophrys dalmatinus, Salaria pavo, Callionymus pusillus, Aphanius iberus, Engraulis encrasicolus, Gobius cobitis, G. niger, G. paganellus, Pomatoschistus marmoratus, Symphodus cinereus, Chelon labrosus, Liza aurata, L. ramado, L. saliens, Mugil cephalus, Diplodus puntazzo, D. sargus sargus, Lithognathus mormyrus, Sarpa salpa, Sparus aurata, Hippocampus guttulatus and Syngnathus abaster. The captures were made in shallow areas of the lagoon during 2002,2004. Significant length,weight relationships were found for all species. [source] | |||||||||||||