scholarly journals Food resource variability in an Australian dryland river: evidence from the diet of two generalist native fish species

2008 ◽  
Vol 59 (2) ◽  
pp. 137 ◽  
Author(s):  
David Sternberg ◽  
Stephen Balcombe ◽  
Jonathan Marshall ◽  
Jaye Lobegeiger

To examine how food resource availability links with natural variation in primary productivity in the Moonie River, south-west Queensland, the diets of two native Australian fish species (Nematalosa erebi and Macquaria ambigua) were examined from fifteen waterholes in February, May and September 2006. N. erebi diets reflected strong ‘boom and bust’ patterns of food consumption, with high concentrations of benthic (non-filamentous) algae during boom (flow) times, moving to higher concentrations of filamentous algae and detritus during bust (no flow) periods. M. ambigua diets were primarily dominated by aquatic insects in all sampling periods. Although there was no clear ‘boom to bust’ pattern in relation to flow, M. ambigua secondary prey consumption revealed a compensatory switch between high energy prey (crustaceans) during more productive periods with terrestrial insects during less productive periods. The ability of both species of fish to switch from high to low concentrations of food quality under a variable environmental background allows them to persist through both high productive and low productive periods. This interaction between native biota and variable ‘boom’ and ‘bust’ conditions, and how changes to the natural hydrology will affect it is an important consideration of any future water resource development plans.

2005 ◽  
Vol 187 (17) ◽  
pp. 5937-5945 ◽  
Author(s):  
Ana Segura ◽  
Patricia Godoy ◽  
Pieter van Dillewijn ◽  
Ana Hurtado ◽  
Nuria Arroyo ◽  
...  

ABSTRACT Pseudomonas putida DOT-T1E is tolerant to toluene and other toxic hydrocarbons through extrusion of the toxic compounds from the cell by means of three efflux pumps, TtgABC, TtgDEF, and TtgGHI. To identify other cellular factors that allow the growth of P. putida DOT-T1E in the presence of high concentrations of toluene, we performed two-dimensional gel analyses of proteins extracted from cultures grown on glucose in the presence and in the absence of the organic solvent. From a total of 531 spots, 134 proteins were observed to be toluene specific. In the absence of toluene, 525 spots were clearly separated and 117 proteins were only present in this condition. Moreover, 35 proteins were induced by at least twofold in the presence of toluene whereas 26 were repressed by at least twofold under these conditions. We reasoned that proteins that were highly induced could play a role in toluene tolerance. These proteins, identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry, were classified into four categories: 1, proteins involved in the catabolism of toluene; 2, proteins involved in the channeling of metabolic intermediates to the Krebs cycle and activation of purine biosynthesis; 3, proteins involved in sugar transport; 4, stress-related proteins. The set of proteins in groups 2 and 3 suggests that the high energy demand required for solvent tolerance is achieved via activation of cell metabolism. The role of chaperones that facilitate the proper folding of newly synthesized proteins under toluene stress conditions was analyzed in further detail. Knockout mutants revealed that CspA, XenA, and Tuf-1 play a role in solvent tolerance in Pseudomonas, although this role is probably not specific to toluene, as indicated by the fact that all mutants grew more slowly than the wild type without toluene.


2009 ◽  
Vol 7 (4) ◽  
pp. 701-708 ◽  
Author(s):  
Ana Paula Vidotto-Magnoni ◽  
Edmir Daniel Carvalho

We evaluated the feeding of fish species of the Nova Avanhandava Reservoir, low Tietê River, São Paulo State, Brazil. Fishes were collected in two stretches of the reservoir: Santa Bárbara (14 samples) and Bonito (two samples) between September 2002 and March 2004, using gill and seining nets. The results of stomach contents analysis were expressed with the frequency of occurrence and gravimetric method, combined in the Alimentary Index (AI). The 20 species studied consumed 52 food items, grouped in 10 food categories: aquatic insects, terrestrial insects, crustaceans, fish, macroinvertebrates, microcrustaceans, algae, vegetal matter, detritus/sediment and scales. The aquatic insects (mainly Chironomidae, Odonata and Ephemeroptera) were the most common food resources, consumed by 18 species. The diet composition of the community (species grouped) indicated that the dominant food category in the diet of fishes was aquatic insects (AI = 77.6%), followed by crustaceans (AI = 7.1%). Four trophic guilds were identified according a cluster analysis (Pearson distance): insectivorous (10 species), omnivorous (4 species), detritivorous (3 species) and piscivorous/carcinophagous (3 species). Despite the highest number of species, the insectivorous guild was responsible for more than 80% in captures in number and biomass (CPUEn and CPUEb). The low values of niche breadth presented by all species, along with the low values of diet overlap between species pairs indicate a high degree of food resources partitioning among species. The aquatic insects, despite being the main food resource of insectivorous fishes, also complemented the diet of other species, which demonstrate the importance of this food resource for the fish community, sustaining a high diversity, abundance and biomass of fishes.


1988 ◽  
Vol 66 (12) ◽  
pp. 2611-2617 ◽  
Author(s):  
Peter L. Davies ◽  
Choy L. Hew ◽  
Garth L. Fletcher

Many marine teleosts have adapted to ice-laden seawater by evolving antifreeze proteins and glycoproteins. These proteins are synthesized in the liver for export to the blood where they circulate at levels of up to 20 mg/mL. There are at least four distinct antifreeze protein classes differing in carbohydrate content, amino acid composition, protein sequence, and secondary structure. In addition to antifreeze structural diversity, fish species differ considerably with respect to mechanisms controlling seasonal regulation of plasma antifreeze concentrations. Some species synthesize antifreeze proteins immediately before the onset of freezing conditions, some synthesize them in response to such conditions, whereas others possess high concentrations all year. Endogenous rhythms, water temperature, photoperiod, and pituitary hormones have all been implicated as regulators of plasma antifreeze protein levels. The structural diversity of antifreeze proteins and their occurrence in a wide range of fish species suggest that they evolved separately and recently during Cenozoic glaciation. Invariably, the genes coding for these antifreeze proteins are amplified, sometimes as long tandem arrays, suggesting intense selective pressure to produce large amounts of protein. The distribution of antifreeze gene types among fish species suggests that they could serve as important tools for studying phylogenetic relationships.


1994 ◽  
Vol 51 (3) ◽  
pp. 295-305 ◽  
Author(s):  
Sharyn G. Armstrong ◽  
S.Grant Wyllie ◽  
David N. Leach

1986 ◽  
Vol 43 (8) ◽  
pp. 1534-1546 ◽  
Author(s):  
J. Stevenson Macdonald ◽  
Roger H. Green

Feeding relationships of various fish species, and their relationship to the composition of the surrounding sediments, were observed for 1 yr at two sites in the lower Bay of Fundy region. The fishes were the ocean pout (Macrozoarces americanus, Zoarcidae), winter flounder (Pseudopleuronectes americanus, Pleuronectidae), plaice (Hippoglossoides platessoides, Pleuronectidae), cod (Gadus morhua, Gadidae), and witch flounder (Glyptocephalus cynoglossus, Pleuronectidae). After reducing the size of the data matrix by removing redundant variables, we used discriminant function analysis to assess interspecific diet overlap and the degree to which stomach contents reflect benthic composition. Variables were ranked by their power to discriminate in pairwise comparisons among fish species and between a given fish species and benthic grab samples. Many amphipods are utilized to an equal or greater extent than their abundances in the sediments would suggest. Many annelids are underutilized. Predation by each fish species was a selective process, and interspecific diet differences are related to the morphology of the predator and the behavior and microhabitat of the prey. The fishes diets, however, are also correlated with spatial and temporal changes in the benthic composition. Specific examples are presented. As benthic food abundance increased in the surrounding sediments all predator species increased their food consumption and interspecific diet overlap declined. In some cases the degree of exploitation depended upon the size rather than the abundance of the prey item.


2000 ◽  
Vol 15 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Brent James Smith ◽  
Marthe Monique Gagnon
Keyword(s):  

2018 ◽  
Vol 13 (2) ◽  
pp. 9-21 ◽  
Author(s):  
Marina V. Khlopkova ◽  
Magomedzagid K. Guseynov ◽  
Kais M. Guseynov ◽  
Aysha Sh. Gasanova

Aim. The aim is to study bivalve mollusks of the Dagestan zone of the Caspian Sea as the main feed for all the fish fauna in modern conditions. Material and methods. For the study, are used the materials received in the period of spring-autumn 2015-2017. The collection of material and data processing was carried out according to traditional methods. For the study of nutrition, 30 specimens of each fish species were opened. Such feeding characteristics as the composition of food and the ratio of feed components are given. In the study of shells of bivalve mollusks, the following morphological parameters were measured: length (L), height (H), convexity (Con.), in accordance with the most common measurement technique. Were calculated the allometric coefficients for each year of the life of the individual: the coefficient of elongation (the ratio of height to length), the convexity coefficient (the ratio of convexity to the height). Results. At all periods of the level regime, mollusks are the main food resource of the Caspian Sea. At present they form the basis of the food bolus of the investigated commercial fish species. In June 2017, 25 km north of the city of Makhachkala, after a storm, we found 109 shells of Corbicula fluminalis (O.F. Müller, 1774) (a new invasive atypical species for the investigated aquatorium), the third part of which still had the remains of the ligament. The species was the third most abundant and represented by specimens of all age stages. Conclusions. At present, there are fluctuations in the biomass of the autocolonizers Cerastoderma lamarcki (Reeve), Mytilaster lineatus (Gmelin) and Abra ovata (Philippi), as well as a significant reduction in the range of autochthonous Caspian species, mainly Didacna Eichw. Bivalve mollusks are the main food resource of the Caspian Sea. In conditions of increasing anthropogenic load, further detailed studies of the Caspian's malacofauna are needed.


2013 ◽  
Vol 140 (1-2) ◽  
pp. 238-244 ◽  
Author(s):  
Z. Ahmed ◽  
O. Donkor ◽  
W.A. Street ◽  
T. Vasiljevic

Author(s):  
Ekaterina G. Sakharova ◽  
Irina Yu. Feniova ◽  
Zoya I. Gorelysheva ◽  
Maciej Karpowicz ◽  
Andrzej Górniak

We conducted two mesocosm experiments (2014 and 2017) to determine how invasive zebra mussels affected abundance and structure of phytoplankton community. Algae reaction was different for the introduction of D. polymorpha in 2014 and 2017. There was no influence of zebra mussels on the phytoplankton total abundance; however, it changed the biomass of individual taxa. Cyanoprokaryota reaction as a result the zebra mussels introduction was influenced by the initial phytoplankton structure and initial nitrogen and phosphorus concentrations in water. The biomass of Сyanoprokaryotа decreased at low N:P ratios and increased at high N:P ratios. Dreissena increased the biomass of large green filamentous algae, which is a poor food resource for zooplankton.


2014 ◽  
Vol 29 ◽  
pp. 23-28 ◽  
Author(s):  
František Lukáč ◽  
Jakub Čížek ◽  
Yvonna Jirásková ◽  
Ivan Procházka ◽  
Marian Vlček ◽  
...  

Nanocrystalline powders of iron aluminum alloy of the Fe82Al18 nominal composition were prepared under air, hydrogen and nitrogen atmospheres from the Fe and Al elemental powders by mechanical alloying and also from the conventionally cast Fe82Al18 alloy by the high-energy ball milling. The intensive plastic deformation during high-energy mechanical treatment has introduced high concentrations of open volume defects and contributed to a rapid decrease in the crystallite size down to a nanoscopic range.The hydrogen atmosphere was found to be the most efficient for the Fe-Al mechanical alloying since it has resulted into the fully alloyed Fe82Al18 after 30 h of milling. On the other hand, the nitrogen and air atmosphere have slightly prevented mechanical alloying and after the same milling time the pure iron particles were still detected in the powder mixtures. This partial suppression of the mechanical alloying process is explained by a formation of thin iron nitride and/or oxide layers on the surface of Fe particles preventing mutual inter-diffusion of Fe and Al atoms.


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