Day- and night-time prey availability for waterbirds in a tropical lagoon

1995 ◽  
Vol 73 (5) ◽  
pp. 869-878 ◽  
Author(s):  
Raymond McNeil ◽  
Oscar Díaz Díaz ◽  
Ildefonso Liñero A. ◽  
José R. Rodríguez S.
Keyword(s):  
Prey Availability ◽  
The Other ◽  
Shallow Waters ◽  
Sampling Techniques ◽  
Benthic Organisms ◽  
Dabbling Ducks ◽  
Night Time ◽  
Marsh Birds ◽  
Tropical Lagoon ◽  
Time Availability

One of the main hypotheses formulated to explain why marsh birds, wildfowl, and shorebirds forage at night postulates that the birds prefer to feed at night because the feeding opportunities are most profitable then. To investigate this hypothesis, we compare day- and night-time availability and describe the diel abundance rhythm of swimming and benthic organisms inhabiting the shallow waters of a tropical lagoon complex in northeastern Venezuela. Three sampling techniques were used by day and by night: net sampling for swimming organisms, core sampling for those in the sediments (10 cm deep), and sight counts for organisms on the surface of substrata. Overall, in the case of swimming organisms, fishes, isopods, amphipods, shrimps (Penaeus spp.), and corixids were 3–30 times more abundant at night than during daytime. In general, infaunal organisms were about equally abundant during the day and the night, or slightly more abundant during the day. At the surface, isopods, amphipods, and polychaetes were greater than 10 times more abundant at night than during the day. However, gastropods were slightly more numerous during daytime on the substrata, while pelecypods were about equally numerous during day- and night-time. Fiddler crabs (Uca sp.) were generally more available during daytime. Considering all organisms together, the prey for marsh birds, wildfowl, and shorebirds were significantly more abundant at night. In conclusion, tactile-foraging species (e.g., spoonbills, skimmers, ibises, dabbling ducks, and several species of shorebirds) should profit by foraging only at night and resting during the day, and foraging during daylight only to top up a nighttime deficit. On the other hand, despite limited nighttime visual capacity, some sight-feeding species (e.g., herons, plovers) may take advantage of increased prey availability at night, at least on moonlit nights.

Temporal distribution of crustaceans in forested freshwater wetlands: responses to changes in the hydroperiod

Crustaceana ◽  
2017 ◽  
Vol 90 (6) ◽  
pp. 721-734
Author(s):  
Francisco Correa-Araneda ◽  
Patricio De los Ríos-Escalante ◽  
Ricardo Figueroa ◽  
Luciano Parra-Coloma
Keyword(s):  
Temporal Distribution ◽  
Hydrological Regime ◽  
Forested Wetlands ◽  
Species Level ◽  
Freshwater Wetlands ◽  
The Other ◽  
Sampling Techniques ◽  
Southern Chile ◽  
Ephemeral Wetlands ◽  
Hydrological Regimes

Studies on crustacean communities in Chilean wetlands are scarce. The aim of this study was to characterize the crustacean community in forested wetlands from southern Chile and to establish their relation with the variations in the hydrological regime. In total, 540 samples were taken using three complementary sampling techniques in five wetlands during 2011 and 2012. The results show a total of four species of crustaceans, of which the amphipod Hyalella patagonica (Cunningham, 1871) (Hyalellidae) was dominant in ephemeral wetlands and the isopod Heterias exul (Mueller, 1892) (Janiridae) in permanent wetlands. The other species (the decapods Parastacus pugnax (Poeppig, 1835) (Parastacidae) and Aegla araucaniensis (Jara, 1980) (Aeglidae)) showed abundances below 6% in all wetlands. The identified crustaceans presented marked variations, both at a temporal scale and between wetlands with different hydrological regimes, both at the species level and at the crustacean community level. These patterns were mainly explained by changes registered in the annual hydroperiod and our results conform to the existing information that would indicate the importance of the inclusion of hydrological patterns in descriptions of freshwater communities.

scholarly journals Dual Predation by Bacteriophage and Bdellovibrio bacteriovorus Can Eradicate Escherichia coli Prey in Situations where Single Predation Cannot

2020 ◽  
Vol 202 (6) ◽  
Author(s):  
Laura Hobley ◽  
J. Kimberley Summers ◽  
Rob Till ◽  
David S. Milner ◽  
Robert J. Atterbury ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Prey Availability ◽  
The United States ◽  
The Other ◽  
Bacteriophage Therapy ◽  
Bdellovibrio Bacteriovorus ◽  
Content Type ◽  
E Coli ◽  
Rapid Acquisition ◽  
Predatory Bacteria

ABSTRACT Bacteria are preyed upon by diverse microbial predators, including bacteriophage and predatory bacteria, such as Bdellovibrio bacteriovorus. While bacteriophage are used as antimicrobial therapies in Eastern Europe and are being applied for compassionate use in the United States, predatory bacteria are only just beginning to reveal their potential therapeutic uses. However, predation by either predator type can falter due to different adaptations arising in the prey bacteria. When testing poultry farm wastewater for novel Bdellovibrio isolates on Escherichia coli prey lawns, individual composite plaques were isolated containing both an RTP (rosette-tailed-phage)-like-phage and a B. bacteriovorus strain and showing central prey lysis and halos of extra lysis. Combining the purified phage with a lab strain of B. bacteriovorus HD100 recapitulated haloed plaques and increased killing of the E. coli prey in liquid culture, showing an effective side-by-side action of these predators compared to their actions alone. Using approximate Bayesian computation to select the best fitting from a variety of different mathematical models demonstrated that the experimental data could be explained only by assuming the existence of three prey phenotypes: (i) sensitive to both predators, (ii) genetically resistant to phage only, and (iii) plastic resistant to B. bacteriovorus only. Although each predator reduces prey availability for the other, high phage numbers did not abolish B. bacteriovorus predation, so both predators are competent to coexist and are causing different selective pressures on the bacterial surface while, in tandem, controlling prey bacterial numbers efficiently. This suggests that combinatorial predator therapy could overcome problems of phage resistance. IMPORTANCE With increasing levels of antibiotic resistance, the development of alternative antibacterial therapies is urgently needed. Two potential alternatives are bacteriophage and predatory bacteria. Bacteriophage therapy has been used, but prey/host specificity and the rapid acquisition of bacterial resistance to bacteriophage are practical considerations. Predatory bacteria are of interest due to their broad Gram-negative bacterial prey range and the lack of simple resistance mechanisms. Here, a bacteriophage and a strain of Bdellovibrio bacteriovorus, preyed side by side on a population of E. coli, causing a significantly greater decrease in prey numbers than either alone. Such combinatorial predator therapy may have greater potential than individual predators since prey surface changes selected for by each predator do not protect prey against the other predator.

scholarly journals The genus Alcyonium (Octocorallia: Alcyonacea: Alcyoniidae) in Chile

Zootaxa ◽  
2007 ◽  
Vol 1607 (1) ◽  
pp. 1-19 ◽  
Author(s):  
L. P. VAN OFWEGEN ◽  
V. HÄUSSERMANN ◽  
G. FÖRSTERRA
Keyword(s):  
New Species ◽  
The Other ◽  
Shallow Waters ◽  
Sem Images

Four new species of Alcyonium (Octocorallia: Alcyoniidae) are described from Chile. They occur in the shallow waters of the southern fjord region. One of them is an encrusting species, the other three form digitate colonies. Encrusting forms of A. grandis Casas et al., 1997, and A. haddoni Wright & Studer, 1889 were also found in the fjord region, bringing the number of Alcyonium species recorded for Chile to eight. For all six recently collected species SEM images of sclerites are presented, and a key to the Chilean Alcyonium species is included.

Geographic variation of skeletal ontogeny and skull shape in the harbour porpoise (Phocoena phocoena)

2011 ◽  
Vol 89 (9) ◽  
pp. 869-879 ◽  
Author(s):  
A. Galatius ◽  
P.E. Gol’din
Keyword(s):  
Geographic Variation ◽  
Rapid Growth ◽  
Prey Availability ◽  
The Other ◽  
Sea Of Azov ◽  
Phocoena Phocoena ◽  
Skull Shape ◽  
The Sea Of Azov ◽  
The Pacific ◽  
Harbor Porpoises

All extant porpoise species show paedomorphic skeletal traits. These traits are hypothesized to be connected with rapid growth to reproductive size and could thus show geographic variation according to ecological circumstances. To investigate this, skeletal ontogeny was compared among harbour porpoises from California, West Greenland, the inner Danish waters, and the Sea of Azov. Porpoises from California grew to larger sizes than Danish porpoises, which were again larger than Greenlandic porpoises, whereas Azov porpoises were smallest. Size differences were largely attributable to differences in timing of offset of growth. Expression of paedomorphosis followed the same pattern among populations and sexes as adult sizes; Californian porpoises were less paedomorphic than the other populations across all assessed traits, whereas porpoises from Azov were the most paedomorphic. We propose that the larger size and less profound paedomorphism seen in Californian porpoises are attributable to fluctuation of prey availability, owing to variation in upwelling on which productivity in Californian waters depends. Skull shapes after correction for allometry were significantly different among all populations, Sea of Azov porpoises being most divergent. There was no overlap of skull shapes between the Atlantic, the Pacific, and Azov, supporting the current division of harbor porpoises ( Phocoena phocoena (L., 1758)) into three subspecies ( Phocoena phocoena phocoena (L., 1758), Phocoena phocoena relicta Abel, 1905, and Phocoena phocoena vomerina Gill, 1865).

Predation by House Cats, Felis catus (L.), in Canberra, Australia. I. Prey Composition and Preference

1997 ◽  
Vol 24 (3) ◽  
pp. 263 ◽  
Author(s):  
D. G. Barratt
Keyword(s):  
Small Mammals ◽  
Prey Availability ◽  
Felis Catus ◽  
Night Time ◽  
Substantial Impact ◽  
Predatory Behaviour ◽  
Residential Developments ◽  
Prey Composition ◽  
Spatial Habitat

Studies of predation by house cats in Australia have not attempted to compare the composition of prey taken by cats with the relative availability of prey. Information on the composition of vertebrate prey caught by house cats in Canberra was collected by recording prey deposited at cat owners’ residences over 12 months. A total of 1961 prey representing 67 species were collected or reported. In all, 64% of prey were introduced mammals, especially mice and rats, with birds comprising 27% (14% native, 10% introduced, 3% unidentified), reptiles 7%, amphibians 1% and native mammals 1%. Predatory behaviour by house cats appeared largely opportunistic with respect to spatial (habitat) and temporal (daily and seasonal) prey availability and accessibility, although there is mounting evidence from this and other studies that small mammals are the preferred prey. While this means that introduced mice and rats are common prey of house cats in urban and suburban environments, it also suggests that in relatively undisturbed environments adjoining new residential developments, predation by house cats may have a substantial impact on locally abundant, patchily distributed populations of native fauna, particularly mammals. Imposing night-time curfews on cats is likely to lessen predation of mammals but will probably not greatly reduce predation of birds or reptiles.

scholarly journals Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995–1997

2015 ◽  
Vol 33 (1) ◽  
pp. 143-157 ◽  
Author(s):  
K. S. Tanoh ◽  
B. J.-P. Adohi ◽  
I. S. Coulibaly ◽  
C. Amory-Mazaudier ◽  
A. T. Kobea ◽  
...  
Keyword(s):  
Solar Minimum ◽  
Transition Process ◽  
The Other ◽  
Winter Period ◽  
Night Time ◽  
Minimum Period ◽  
Bottom Part ◽  
Layer Height ◽  
Northern Summer ◽  
The One

Abstract. In this paper, we report on the night-time equatorial F-layer height behaviour at Korhogo (9.2° N, 5° W; 2.4° S dip lat), Ivory Coast, in the West African sector during the solar minimum period 1995–1997. The data were collected from quarter-hourly ionograms of an Ionospheric Prediction Service (IPS) 42-type vertical sounder. The main focus of this work was to study the seasonal changes in the F-layer height and to clarify the equinox transition process recently evidenced at Korhogo during 1995, the year of declining solar flux activity. The F-layer height was found to vary strongly with time, with up to three main phases. The night-to-night variability of these morphological phases was then analysed. The early post-sunset slow rise, commonly associated with rapid chemical recombination processes in the bottom part of the F layer, remained featureless and was observed regardless of the date. By contrast, the following event, either presented like the post-sunset height peak associated with the evening E × B drift, or was delayed to the midnight sector, thus involving another mechanism. The statistical analysis of the occurrence of these events throughout the solar minimum period 1995–1997 revealed two main F-layer height patterns, each characteristic of a specific season. The one with the post-sunset height peak was associated with the northern winter period, whereas the other, with the midnight height peak, characterized the northern summer period. The transition process from one pattern to the other took place during the equinox periods and was found to last only a few weeks. We discuss these results in the light of earlier works.

Trophic ecology of a benthic intertidal hydroid, Tubularia crocea, at Mar del Plata, Argentina

2005 ◽  
Vol 85 (2) ◽  
pp. 307-312 ◽  
Author(s):  
Gabriel N. Genzano
Keyword(s):  
Trophic Ecology ◽  
Feeding Rate ◽  
Prey Availability ◽  
Stomach Contents ◽  
Dry Weight ◽  
Benthic Organisms ◽  
Food Items ◽  
The Mean ◽  
The Relationship ◽  
Prey Items

The trophic ecology and seasonal changes in the diet of the intertidal hydrozoan Tubularia crocea were studied analysing the enteron contents of hydranths collected each season of the year. The relationship between feeding rate, prey availability, and re-suspension processes caused by tidal currents was also assessed. The most prevalent food items were diatoms and crustaceans. The most remarkable differences occurred during summer, when crustaceans were more abundant than diatoms. Conversely, diatoms were the most abundant prey during other seasons, and they were almost the only prey found during winter. There was no relationship between abundances of primary prey items in the water column and their occurrences in stomach contents. Instead, most prey items consisted of benthic organisms, primarily two species of diatoms (Grammatophora marina and Licmophora abreviatta) and fragments (usually appendages) of the amphipods Caprella sp. and Jassa falcata. Most food items were digested within 4–4·5 hours. The mean number of items captured per polyp per day was determined to be 115·2±19·2 in summer, 93·6±14·4 in autumn, 76·8±21·6 in winter and 199·2±31·2 in spring. Prey biomass (dry weight) polyp−1 d−1 was 5·1 μg in summer, 2·3 μg in autumn, 1·8 μg in winter, and 6·3 μg in spring. These values, in relation to hydranth biomass (55·3 μg; dry weight), were equivalent to a food intake polyp−1 d−1 of 9·3%, 4·2%, 3·2% and 11·5% of its own weight, respectively.

Phase studies on the iron–selenium system

1968 ◽  
Vol 46 (8) ◽  
pp. 1171-1174 ◽  
Author(s):  
J. E. Dutrizac ◽  
M. B. I. Janjua ◽  
J. M. Toguri
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Differential Thermal Analysis ◽  
The Other ◽  
Sampling Techniques ◽  
Liquid Region ◽  
Consolute Temperature ◽  
Liquid Sampling

The quasi-reduced iron–selenium phase diagram has been determined by a combination of differential thermal analysis, visual polythermal, and liquid sampling techniques. Iron and selenium form two compounds: FeSe2 with a broad stoichiometry range and FeSe2 with a much narrower composition field. The former compound was found to melt congruently at 1070 °C and 53.5 atomic % selenium, while the latter melted incongruently at 585 °C. Two liquid–liquid regions were observed in this system. One occurred above 790 °C from 73.9 atomic % selenium to about 99.92% selenium with a consolute temperature of 1070 °C at approximately 93 atomic % selenium. The other liquid–liquid region extends upwards from 1520 °C and lies between 3 and 39.5 atomic % selenium.

The Achimota Transport Terminal in Accra: A Model Urban Regeneration Project in Ghana?

2015 ◽  
Vol 8 (9) ◽  
pp. 240 ◽  
Author(s):  
Lewis Abedi Asante ◽  
Alexander Sasu ◽  
Jonathan Zinzi Ayitey ◽  
Naana Amakie Boakye-Agyeman
Keyword(s):  
Preventive Maintenance ◽  
Urban Regeneration ◽  
The Other ◽  
Maintenance Cost ◽  
Sampling Techniques ◽  
Economic Dimension ◽  
Corrective Maintenance ◽  
Urban Decay ◽  
Short Period ◽  
Improved Sanitation

<p>Over the years, government has spent millions of taxpayer’s monies to undertake urban regeneration projects (URPs) with the aim of combating the challenges of urban decay in Ghana. Several studies have argued that a number of these URPs have been left to deteriorate because there was no proper plan to maintain them. Amidst these challenges, the Achimota Transport Terminal (ATT) has been tagged as a ‘model URP in Ghana’. This paper finds out the reasons for the tag put on ATT. We adopted purposive, convenience and stratified sampling techniques to select the respondents for this study. We found two reasons for the tag on ATT – one being that the managers of ATT strictly adhere to routine and preventive maintenance practices. However, corrective maintenance was deferred. The other reason is that the terminal meets the physical (adequate parking space, availability of waiting sheds), social (creation of employment, reduction in theft cases and available cars to all destinations in Accra and beyond) and environmental (improved sanitation) dimensions of urban regeneration. Nevertheless, same cannot be said about the economic dimension (low daily sales, high maintenance cost). About 90 percent of the drivers complained vehemently of low daily sales at the terminal. We believe that delaying corrective maintenance when needed may not only mean additional cost when repairs are finally done but has the likelihood of plunging the terminal into a poor state within a short period. Additionally, since the terminal in question is serving as a model for future terminals, planning and designing of such future terminals should aim at meeting all the dimensions of urban regeneration to enhance its usage and sustainability.</p>

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