Рыбы: экология подкаменщика Cottus gobio

Рыбы

Рыбы: экология подкаменщика Cottus gobio.

Volume 11 Issue 3 Page 203 - September 2002

The presence of artificial stones predicts the occurrence of the European bullhead (Cottus gobio) in a regulated lowland river in Flanders (Belgium)

G. Knaepkens1, L. Bruyndoncx1, L. Bervoets2, M. Eens1

Abstract-In a regulated lowland river in Flanders (northern part of Belgium), the locally endangered bullhead was found mainly near bridges. These locations are characterised by the presence of artificial stones and a relatively high water velocity. To preserve and expand the few remaining bullhead populations, the removal of these stones should be avoided and new suitable habitats should be created.

Рыбы: экология колюшки.

Volume 10 Issue 4 Page 191 - December 2001

Feeding ecology and habitat of the threespine stickleback, Gasterosteus aculeatus microcephalus, in a remnant population of northwestern Baja California, Mexico

S. Sanchez-Gonzales, G. Ruiz-Campos, S. Contreras-Balderas

Abstract -The feeding ecology and habitat of the threespine stickleback (Gasterosteus aculeatus microcephalus Girard, 1854) was studied from November 1996 to May 1997 in a remnant population of northwestern Baja California, Mexico. The analysis of the stomach content of 179 individuals (25 to 56 mm standard length [SL]) showed a diet dominated by cyclopoid copepods (43.8%) and chironomid larvae (39.1%). Diet in relation to size and sex of the fish was dominated by copepods in autumn and winter and by chironomid larvae during spring. Diet overlap (Schoeners index) was significant (=" border=0 src="/na102/home/ACS/journals/entities/2265.png"60%) between fish size-classes in January, March and April and between sexes for most sampling months. The average size of prey consumed was independent of fish mouth size. The feeding strategy of the threespine stickleback shifted from opportunist in winter to specialist in spring.

Рыбы: экология колюшки.

Volume 10 Issue 3 Page 127 - September 2001

Does timing of daily feeding affect growth rates of juvenile three-spined sticklebacks, Gasterosteus aculeatus L?

M. Ali1,2, R. J. Wootton1

Abstract -To assess the consequences of unpredictability in the availability of food, this study measured the effect of timing of the daily feeding on food consumption and growth rates of juvenile Gasterosteus aculeatus. The experiment lasted 21 days at 14шC and a photoperiod of 10 hours of light and 14 hours of dark. Fish were housed individually and allocated at random to three treatments. The mean initial weight of fish was 0.402 g. Group 1 were fed live enchytraeid worms for 2 h after lights came on (morning), group 2 was offered food for 2 h randomly at any time of the day (random) during the light period and group 3 received food for 2 h before the lights went off (evening). There was no significant effect of timing of feeding on mean daily food consumption, which was 0.052 g day1. Daily consumption on the random schedule was more irregular than on the two fixed schedules. Timing of feeding had no significant effect on mean specific growth rate (G) (2.42% day1), gross growth efficiency (23.3%), white muscle RNA:DNA ratio (5.6), carcase lipid content (31.7% dry wt) and carcase dry matter content (27.4% wet wt). Thus, a lack of predictability in the availability of food during the light period of the day did not impose a detectable cost on the growth performance of the stickleback.

Эстуарии: питание лосося.

Volume 10 Issue 3 Page 177 - September 2001

Estuarine predation on radiotagged wild and domesticated sea trout (Salmo trutta L.) smolts

C. Dieperink, S. Pedersen, M. I. Pedersen

Abstract -Avian predation on emigrating wild and domesticated sea trout smolts was investigated in a fjord in the western Baltic Sea. In April 1997, 50 domesticated and 50 wild smolts were intraperitoneally tagged with radio-transmitters and released in a small coastal stream. Predation was recorded by signal interception in an estuarine breeding colony of cormorants and herons near the outlet of the stream. Of the 78 emigrating smolts, 51 (65%) were recorded as eaten. Predation rates were significantly higher among small than large smolts and significantly higher among domesticated smolts. The first 2 days after entering the sea, both wild and domesticated smolts suffered a severe daily predation rate (range 20-34%). The results support the hypothesis of a transient period immediately after exposure to full-strength sea water, where smolts experience an elevated risk of predation. A transient increase in postsmolt mortality may be found also in moderately saline environments (20-23 ppt).

Рыбы: изменения сообщества от ручья к эстуарию.

Fish community variation along physical gradients in short streams of

northern Spain and the disruptive effect of dams.

Hydrobiologia 321(2). 1996. 155-163.

Abstract

Relationships between the fish community and selected habitat features

were examined in a set of short temperate streams located at the northern

end of the Iberian Peninsula. The fish fauna in these streams consists

mostly of diadromous or estuarine species. Species richness and diversity

increased with stream order, depth and width and decreased with elevation

and distance from the sea. Stream order (positively) and elevation

(negatively) were the two variables most highly correlated with species

richness and diversity; higher order streams (order 3-4) showed greater

values of species diversity than lower order ones (order 1) even when the

elevation effect was removed. Addition of species in the downstream

direction, but no replacement or loss was evidenced. We also compared the

observed values of species diversity with those predicted from habitat

features for a set of locations above unpassable dams. A great majority of

the sites showed lower than predicted diversity values, which is an

expected outcome for this mainly migratory fish fauna.

Рыбы: влияние загрязнений, Амазония.

Silva C P D.

Community structure of fish in urban and natural streams in the Central

Amazon.

Amazoniana 13(3-4). 1995. 221-236.

A community of fish from the Quarenta stream were shown to have been

affected by urban pollution (domestic drains and industrial effluents).

The structure of the community, number of individuals, richness of

species, index of diversity and the degree of stability were significantly

different from those of the Candiru Stream, which is still in a natural

state. The low concentration of dissolved oxygen and the low diversity of

habitats are the principal factors that are influencing the fish community

of the Quarents stream.

Рыбы: распределение речных донных видов в регион.масштабе.

Taylor C M.

Institution

Dep. Biol. Sci., Mississippi State Univ., Mississippi State, MS 39762,

USA.

Title

Abundance and distribution within a guild of benthic stream fishes: Local

processes and regional patterns.

Source

Freshwater Biology 36(2). 1996. 385-396.

1. Spatial patterns at regional and local scales were examined for

evidence that species interactions can influence distribution and

abundance within a guild of benthic fishes in upland streams of Oklahoma,

U.S.A. Three groups of community patterns were examined: the species-area

relationship, species-habitat associations, and interspecific

associations. 2. The species-area relationship for riffle habitats was

compared to a null species-area model based on random placement. The

observed species-area curve was steeper resulting in less species per unit

area in small streams than predicted by the null model. 3. Small,

species-poor streams had summed fish densities at least as high as larger,

species-rich streams, suggesting density compensation. 4. Several

significant patterns of negative covariation were found among species at

the regional scale, before and after statistically accounting for effects

due to measured habitat variables. 5. For two of these negatively

covarying taxa (Cottus carolinae and Etheostoma spectabile), the influence

of each species on the distribution of the other was evaluated

experimentally in field enclosures varying in depth and current velocity.

The sculpin C. carolinae caused a shift in habitat use by the darter E.

spectabile, but no reciprocal shift was found. 6. These results indicate

an agreement between local and regional patterns of distribution for C.

carolinae and E. spectabile and suggest that biotic interactions can

influence regional patterns of distribution for species within this guild.

Рыбы: влияние форели на структуру бентоса.

The effects of trout-farm effluents on benthic invertebrate community

structure in rivers in the south-western Cape, South Africa.

Southern African Journal of Aquatic Sciences 21(1-2). 1995. 3-21.

The South-western Cape is currently responsible for 45% of the total

annual trout production in South Africa and further expansion of this

industry in the region is likely. A preliminary survey of seven trout

farms situated on the upper reaches of rivers in the southwestern Cape was

undertaken to determine whether there was a common trend in their effect

on the rivers. Results indicated that the impact of the farms on the

benthic invertebrate communities of the rivers ranged from mild to severe,

based on the degree of change in the structure of the communities from

upstream to downstream of the effluent outlets. Those farms situated on

mountain streams had the greatest impact and those on the downstream

foothill had a lesser impact. The reduced impact in the foothill zone was

probably because these reaches were already disturbed by other catchment

activities. Of the three farms that were situated on mountain streams and

source areas, two used plastic portapools and the third earth dams. There

was a substantial increase in the number of oligochaetes downstream of

both 'portapool' farms and yet, despite being situated in the same

sensitive river zone, this did not occur downstream of the farm that used

earth dams. The general impact of trout farm effluent on the

mountain-stream and source zones was to eliminate or greatly reduce the

number of Limnichidae, Helodidae, Plecoptera, Elmidae, Heptageniidae and

Ephemerellidae, and, in the case of portapool farms, to replace these with

Naididae, Lumbriculidae, Chironomidae and Planaria. Once-off chemical

samples were also collected at each site and, acknowledging the

limitations of the sampling strategy, results showed that the particulate

fraction of the effluent was probably responsible for the recorded

reaction of the biota.

Рыбы горных рек.

Authors: Rahel-FJ Hubert-WA

Title: Fish Assemblages and Habitat Gradients in a Rocky-

Mountain Great-Plains Stream - Biotic Zonation and

Additive Patterns of Community Change

Source: TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY

1991, Vol 120, Iss 3, pp 319-332

Abstract:

We examined the importance of zonation and species

additions in explaining longitudinal changes in the fish

assemblage of a Rocky Mountain stream that descends onto the

Great Plains of Wyoming. Community changes along an elevational

gradient from 2,234 to 1,230 m above mean sea level reflected a

combination of zonation and downstream addition of species.

Zonation was evident on a broad spatial scale as a result of

stream temperatures. A coldwater trout (Salmonidae) assemblage

dominated headwater reaches but was replaced by a warmwater

minnow-sucker (Cyprinidae-Catostomidae) assemblage below 2,000

m. Within the warmwater zone, fish community change was due

mainly to the addition of new species downstream. Headwater

sites were dominated by members of the insectivore feeding

guild, and other trophic guilds were added downstream. The

major gradient of habitat change downstream consisted of a

decrease in pool habitat and increases in stream width, depth,

current velocity, turbidity, and proportion of the channel

consisting of run habitat. Minor gradients of of habitat change

involved streambank condition and substrate particle size.

Contrary to streams in forested regions, habitat diversity did

not increase downstream, suggesting that increased living space

and moderating environmental conditions contributed to the

downstream increase in species richness. Local habitat

modification due to cattle grazing or alterations in streamflow

caused minor changes in fish assemblages but did not disrupt the

dominant longitudinal patterns. Broad-scale zonation based on

temperature regime and additive patterns within zones should

typify other streams originating in montane regions.

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