Spatial distribution of Aegla rostrata Jara, 1977 (Decapoda, Anomura, Aeglidae) in the littoral of Pullinque Lake (39°S, North Patagonia, Chile)

Crustaceana ◽  
2019 ◽  
Vol 92 (4) ◽  
pp. 485-493
Author(s):  
Patricio De Los Ríos ◽  
Jorge Farias Avendaño ◽  
Maria Jesús Suazo
Keyword(s):  
Resource Competition ◽  
Benthic Fauna ◽  
Territorial Behaviour ◽  
Southern Chile ◽  
North Patagonia ◽  
The North ◽  
Important Prey ◽  
Organic Debris ◽  
Chilean Patagonia ◽  
Introduced Fishes

Abstract The freshwater anomuran crabs of the genus Aegla are widespread throughout lakes and rivers in central and southern Chile. They form an important component of the benthic fauna, because the species of the genus are shredders of organic debris and also make an important prey for native and introduced fishes. Nevertheless, the ecology of this genus has been poorly studied in lakes in comparison to rivers. The aim of the present study was a description of the spatial pattern of distribution of an Aegla rostrata population from the littoral zone of Pullinque Lake, in the north of Chilean Patagonia. The results revealed a low density (1.0 ± 0.8 ind/m2), that had a uniform pattern, and has a positive binomial distribution. The results would indicate that the studied species would have territorial behaviour that would be associated with interspecific resource competition. The observed results would agree with observations for the benthic zones in Chilean Patagonian lakes, where Aegla would show territorial behaviour.

Benthic Fauna Colonization of a New Reservoir with Particular Reference to the Chironomidae

1970 ◽  
Vol 27 (2) ◽  
pp. 213-232 ◽  
Author(s):  
C. G. Paterson ◽  
C. H. Fernando
Keyword(s):  
Dominant Species ◽  
Dominance Hierarchy ◽  
Benthic Fauna ◽  
Partial Loss ◽  
Organic Debris ◽  
Wide Range ◽  
The Rich ◽  
Laurel Creek ◽  
Chironomid Fauna ◽  
New Reservoir

At the time of first filling of Laurel Creek Reservoir in the spring of 1967 the benthic fauna consisted of submerged terrestrial organisms and obligate and facultative rheophilic species. Two months after initial filling substantial populations of colonizing limnophilic species developed in the habitat whereas the terrestrial and obligate rheophilic components were lost. By the 4th month the fauna was dominated by euryoxybiontic limnophiles and by facultative species. In the period immediately prior to reservoir drainage in the autumn of 1967 the population densities of the euryoxybiontic chironomids declined whereas polyoxybiontic species continued to increase in abundance. These changes in the dominance hierarchy of the chironomid fauna were associated with the partial loss of the rich deposits of organic debris by siltation and decomposition. Survival of winter drainage of the reservoir by many limnophilic species produced an appreciably different pattern of colonization when the reservoir refilled in 1968. During the second summer of the reservoir's existence most euryoxybiontic chironomids further declined in abundance and were replaced by polyoxybiontic forms as the dominant species. The facultative species originally derived from the creek fauna are adapted to a wide range of environmental conditions and the modifications of the reservoir habitat with time had little effect on their abundance.

scholarly journals Artificial light in baited pots substantially increases the catch of cod (Gadus morhua) by attracting active bait, krill (Thysanoessa inermis)

2018 ◽  
Vol 75 (6) ◽  
pp. 2257-2264 ◽  
Author(s):  
Odd-Børre Humborstad ◽  
Anne Christine Utne-Palm ◽  
Michael Breen ◽  
Svein Løkkeborg
Keyword(s):  
Light Source ◽  
North Atlantic ◽  
Coastal Waters ◽  
Gadus Morhua ◽  
Catch Rate ◽  
Light Sources ◽  
The North ◽  
Important Prey ◽  
Large Numbers ◽  
Per Se

Abstract The use of pots in the north Atlantic finfish fisheries is negligible because this fishing method typically has a low capture efficiency. Large numbers of individuals encounter baited pots, but the proportions of fish that enter the pot and become caught are low. Krill, which constitutes an important prey for cod (Gadus morhua), is attracted by light. The catching efficiency of baited cod pots with three light sources with different colours and intensities (white: 9744 mW m−2, white: 23 mW m−2, green: 8 mW m−2) were tested in coastal waters in northern Norway. Pots with the light source of highest intensity gave a 17 times higher catch rate of cod than that of control pots (with bait only). The light source of medium intensity gave about a five times higher catch rate, whereas the weakest light did not influence the catch. Cod caught in pots with light had more krill and arrowworms in their stomach and were observed feeding on these preys inside the pot. We concluded that light sources of increasing intensity attract more krill, and that cod were attracted into the pot by the dense swarms of prey and not the light per se.

Paleomagnetism of the North Patagonian batholith, southern Chile. An exercise in shape analysis

2000 ◽  
Vol 326 (1-2) ◽  
pp. 185-202 ◽  
Author(s):  
M. Beck ◽  
R. Burmester ◽  
J. Cembrano ◽  
R. Drake ◽  
A. Garcia ◽  
...  
Keyword(s):  
Shape Analysis ◽  
Southern Chile ◽  
The North

BIOLOGICAL MONITORING OF THE FORTIES OILFIELD (NORTH SEA)

1983 ◽  
Vol 1983 (1) ◽  
pp. 405-414 ◽  
Author(s):  
J. P. Hartley ◽  
J. Ferbrache
Keyword(s):  
North Sea ◽  
Biological Effects ◽  
Monitoring Program ◽  
Benthic Fauna ◽  
Sediment Type ◽  
The North ◽  
Naturally Occurring ◽  
The North Sea ◽  
Similar Survey ◽  
Benthic Sediments

ABSTRACT The Forties Oilfield (the largest in the U.K. sector of the North Sea) has been in production since September 1975. In June 1975, a quantitative survey of the benthic sediments and fauna over the area was made at the start of an environmental monitoring program for the field. The results of a repeat survey carried out after three years of production have been reported by Hartley.13 This paper presents data from a third similar survey in June 1981 and compares the findings with those of the earlier surveys. The benthic fauna of the Forties Field is rich and diverse and qualitatively corresponded well in 1981 to previous descriptions. Naturally occurring gradients in both the sediment type and fauna are a feature of this area. Changes in the densities of certain species were noted at some sites in 1981, including increases in certain opportunistic forms. Although no areas of biological effect could be delineated around the four production platforms, the industrial activity in the field may be implicated in the changes found at several stations. The hydrocarbon content of the sediments was low and, with one possible exception, did not appear related to the biological changes noted. The results to date suggest that offshore oilfields in deep water, developed using water-based drill fluids, present relatively few biological problems in the short term. Since no major biological effects have been found after six years of drilling and production, a reduced program of monitoring is recommended to maintain biological surveillance during the life of the field.

New additions to the hydroids (Cnidaria: Hydrozoa) from the fjords region of southern Chile

Zootaxa ◽  
2009 ◽  
Vol 2019 (1) ◽  
pp. 1-28 ◽  
Author(s):  
HORIA R. GALEA ◽  
VERENA HÄUSSERMANN ◽  
GÜNTER FÖRSTERRA
Keyword(s):  
Junior Synonym ◽  
Southern Chile ◽  
Male And Female ◽  
The North ◽  
Present Collection ◽  
The Family ◽  
First Time ◽  
Eleven Species

We report upon eleven species of thecate hydroids collected during a recent scientific expedition to the North Patagonian Zone between southern Chiloé and Puyuguapi fjord/ Magdalena Island. One species belongs to the family Haleciidae Hincks, 1868, four to the family Sertulariidae Lamouroux, 1812, and six to the family Campanulariidae Hincks, 1868. Of them, Halecium cymiforme Allman, 1888 and Symplectoscyphus leloupi El Beshbeeshy, 1991 are redescribed based on new, fertile material. Sertularella allmani Hartlaub, 1901 is assigned to the synonymy of S. antarctica Hartlaub, 1901. Campanularia subantarctica Millard, 1971 is considered as a junior synonym of C. lennoxensis Jäderholm, 1903, and data on both the male and female gonothecae are provided. A variant of Clytia gigantea (Hincks, 1866) with smaller hydrothecae than usual is described. Sertularella sanmatiasensis El Beshbeeshy, 1991 is recorded from Chile for the first time. Although not belonging to the present collection, several notes on Kirchenpaueria curvata (Jäderholm, 1904) are provided.

scholarly journals Orographic Precipitation in Coastal Southern Chile: Mean Distribution, Temporal Variability, and Linear Contribution

2016 ◽  
Vol 17 (4) ◽  
pp. 1185-1202 ◽  
Author(s):  
R. Garreaud ◽  
M. Falvey ◽  
A. Montecinos
Keyword(s):  
Time Scales ◽  
Temporal Variability ◽  
River Flow ◽  
Rainfall Variability ◽  
Southern Chile ◽  
Flow Measurements ◽  
The North ◽  
The Pacific ◽  
Northern Half ◽  
Orographic Enhancement

Abstract The Nahuelbuta Mountains (NM) are a semielliptical massif 1300 m high in coastal southern Chile (37°–38°S) facing frontal storms that move from the Pacific. Mean precipitation between 900 and 1200 mm yr−1 is observed in the surrounding lowland, but river flow measurements suggest values ≥3000 mm yr−1 atop the mountains. To verify and characterize such marked orographic enhancement, 15 rain gauges were deployed around and over the NM. The observations were supplemented by a high-resolution WRF simulation and linear theory (LT) modeling during the winter of 2011. The estimated mean precipitation increases gradually from offshore (~1000 mm yr−1) to the north-facing foothills (2000 mm yr−1). The precipitation rapidly increases in the upslope sector to reach ~4000 mm yr−1 over the northern half of the NM elevated plateau, and decreases farther south to reach background values 20–30 km downstream of the mountains. The upstream (downstream) orographic enhancement (suppression) was relatively uniform among storms when considering event accumulations but varied substantially within each storm, with larger modifications during pre- and postfrontal stages and minor modifications during the brief but intense frontal passage. WRF results are in good agreement with observations in terms of seasonal and daily mean rainfall distributions, as well as temporal variability. Given its linear, steady-state formulation, the LT model cannot resolve rainfall variability at short (hourly) time scales, which in WRF is at least characterized by transient, mesoscale rainbands. Nonetheless, the rainbands are mobile so the accumulation field at monthly or longer time scales produced by the linear model is remarkably similar to its WRF counterpart.

Environmental factors influencing the distribution and abundance of the introduced signal crayfish in the north of Iberian Peninsula

2017 ◽  
Vol 68 (5) ◽  
pp. 900 ◽  
Author(s):  
I. Vedia ◽  
D. Galicia ◽  
E. Baquero ◽  
J. Oscoz ◽  
R. Miranda
Keyword(s):  
Aquatic Ecosystems ◽  
Procambarus Clarkii ◽  
Lower Proportion ◽  
Native Fish ◽  
Limiting Factor ◽  
Northern Spain ◽  
Signal Crayfish ◽  
The North ◽  
Organic Debris ◽  
Invasive Crayfish

The identification of habitat requirements of invasive species is essential to evaluate their spread and to assess the vulnerability of recipient ecosystems. We studied the distribution and abundance of the invasive signal crayfish (Pacifastacus leniusculus) in 43 sites in northern Spain and analysed the relationships with several abiotic and biotic parameters of the aquatic ecosystems. Our results indicated that the abundance of signal crayfish was positively associated with vegetation cover and negatively associated with boulders. Also, its abundance was positively correlated with water temperature, organic matter, cations (e.g. sodium), anions (e.g. sulfates) and abundance of some native fish species (Parachondrostoma miegii and Luciobarbus graellsii). We concluded that the habitat of signal crayfish is among salmonid stretches (headwaters) with cold waters and low proportion of organic debris, and among cyprinid stretches (low waters) with warmer waters which it inhabits with another invasive crayfish, the red swamp crayfish (Procambarus clarkii). Our analysis indicated that the presence of signal crayfish is limited in the uppermost stretches by lower water temperatures and a lower proportion of organic debris. The existence of a natural environmental limiting factor in upstream reaches facilitates the conservation of aquatic ecosystems and native fauna.

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