База резюме и ссылок по экологии бентоса

Питание птиц в водотоках.

Title: Exploitation of Prey by a River Bird, the Dipper Cinclus-

Cinclus (L), Along Acidic and Circumneutral Streams in

Upland Wales

Source: FRESHWATER BIOLOGY

1991, Vol 25, Iss 1, pp 105-116

Language: English

Document type: Article

Addresses:

UNIV-WALES, COLL CARDIFF, NATL RIVERS AUTHOR, CATCHMENT RES

GRP, PENYFAI LANE, LLANELLI SA15-4EL, DYFED, WALES

ROYAL-SOC-PROTECT-BIRDS, WALES OFF, NEWTOWN SY16-1AP, POWYS,

WALES

Keywords Plus:

GROWTH; CATCHMENT; WYE; PREDATION; SIZE

Abstract:

1. The diet of the Eurasian dipper Cinclus cinclus, a

riverine bird from a globally widespread genus, was assessed

through all stages of its annual cycle using published data and

field studies from streams of contrasting chemistry. Time-

activity budgets were also compiled throughout the year and used

to estimate annual energy requirements from the stream

ecosystem.

2. The annual energy requirements for a territorial pair

ranged from 148,000 to 158,000 kJ yr-1 depending on whether one

or two broods were reared. After allowing for assimilation

efficiency, these requirements were estimated to represent 10.5-

11.0 kg dry mass of fish and invertebrates. Using

representative values for territory size (4680-11,250 m2),

annual exploitation of secondary production was estimated at

0.93-2.35 g dry mass m-2.

3. Several features combined to focus the predatory load

on certain organisms over different stages of the annual cycle.

These included the availability and selection of alternative

prey, the need to provision nestlings with large items such as

trichopteran larvae, and the use by females of calcium-rich prey

such as fish prior to egg formation.

4. Across their range of territory size, annual

exploitation (dry mass) by dippers was estimated at 0.06-0.29 g

m-2 for Plecoptera, 0.02-0.22 g m-2 for Ephemeroptera, 0.59-1.11

g m-2 for Trichoptera and 0-0.78 g m-2 for fish. Exploitation

of Ephemeroptera, Trichoptera and fish were all highest in

circumneutral streams, but exploitation of Plecoptera was

highest in acidic streams because other prey were scarce.

5. Cottids dominated the fish component of the diet.

Influences on their density could be substantial according to

available data on production in Welsh streams. Hydropsychids

and limnephilids dominated the trichopteran component, with

exploitation again representing potentially substantial amounts

of production. Contemporaneous data are required on benthic

production and exploitation by the birds.

6. The ecological role of birds in rivers particularly,

and aquatic ecosystems generally, is currently neglected but

worthy of considerable research effort.

Влияние размера поедателя на перифитон.

Title: Effects of Herbivore Size and Hunger Level on Periphyton

Communities

Source: JOURNAL OF PHYCOLOGY

1991, Vol 27, Iss 1, pp 54-59

Language: English

Document type: Article

Addresses:

OAK-RIDGE-NATL-LAB, DIV ENVIRONM SCI, POB 2008, BLDG 1504,

OAK-RIDGE, TN 37831, USA

Author keywords:

Cocconeis; Competition; Elimia; Growth Form; Herbivory;

Periphyton; Snails; Stigeoclonium; Streams

Keywords Plus:

PHYTOPLANKTON COMMUNITY; CADDISFLY POPULATION; STREAM;

COMPETITION; INSECT

Abstract:

The effects of herbivore size and hunger level were tested

on lotic periphyton community structure and ash-free dry

mass(AFDM). My hypotheses were 1) that small herbivores would

remove more periphyton per units biomass than large herbivores

of the same species because of energetic demands and 2) that

within the same size class, starved herbivores would remove more

periphyton than nonstarved herbivores. The herbivore used was

the prosobranch snail Elima clavaeformis Lea. Seven treatments

were employed: 1) no snails (control); 2) small ''starved''

snails; 3) large ''starved'' snails; 4) small and large

''starved'' snails; 5) small fed snails; 6) large fed snails;

and 7) small and large fed snails. Although snails removed

significant amounts of periphyton AFDM relative to controls,

neither snail size nor degree of starvation had a significant

effect on loss of total AFDM. Small snails removed

significantly more erect forms of Stigeoclonium tenue (C. A.

Ag.) Kutz. than large snails, but snail size had no other

significant effect. Starved snails removed significantly more

Cocconeis placentula Ehr. than fed snails, suggesting that after

the more susceptible growth forms (e.g. erect Stigeoclonium)

were removed, Cocconeis cells became more vulnerable to grazing

by hungry snails. When small and large snails were combined in

chambers, large snails gained weight over time, whereas small

snails lost weight. These results suggest that intraspecific

competition may occur within populations of Elimia.

Питание бентоса опадом в Миссисипи.

Authors: Beiser-MC Testa-S Aumen-NG

Title: Macroinvertebrate Trophic Composition and Processing of

4 Leaf Species in a Mississippi Stream

Source: JOURNAL OF FRESHWATER ECOLOGY

1991, Vol 6, Iss 1, pp 23-33

Language: English

Document type: Article

Addresses:

UNIV-MISSISSIPPI, DEPT BIOL, FRESHWATER BIOL PROGRAM,

UNIVERSITY, MS 38677, USA

Keywords Plus:

WOODLAND STREAM; LITTER DECOMPOSITION; LEAVES;

INVERTEBRATES; COLONIZATION; SHREDDERS; BREAKDOWN; INSECTS;

ECOLOGY; FRESH

Abstract:

The benthic invertebrate community associated with leaf

packs of four taxa of deciduous leaves was examined along with

changes in community composition occurring during leaf

decomposition. Dogwood leaves were processed most rapidly,

followed by tulip poplar, hickory, and oak, with average decay

coefficients (k) of 0.059, 0.046, 0.026, and 0.021 d-1,

respectively. Twenty-five taxa of macroinvertebrates were

collected from the leaf packs, and most were insects.

Trichoptera were the most commonly collected organisms and were

dominated by Lepidostoma sp. The majority of the taxa occurred

on all leaf species and in similar numbers. Among the collected

taxa were eight shredders, five collectors, nine predators, and

two scrapers. Invertebrates colonized leaf packs two days post-

introduction, suggesting that shredders did not require pre-

conditioned leaves. Attempts to correlate the number of

invertebrates with percent leaf material remaining were

unsuccessful. The greatest macroinvertebrate abundance and

diversity occurred on oak leaves. There was no discrimination

between leaf species by the majority of the colonizing

invertebrates, with over 96% of the invertebrate taxa found on

all four leaf species. The results suggest that invertebrates

in warmwater streams are able to exploit allochthonous resources

over a longer time period than invertebrates in higher latitude

streams.

Пищевые взаимосвязи.

Freshwater Biology Volume 47 Issue 7 Page 1257 - July 2002

Predation on mayfly nymph, Baetis rhodani, by native and introduced Gammarus: direct effects and the facilitation of predation by salmonids

DAVID W. KELLY, JAIMIE T. A. DICK & W. IAN MONTGOMERY

1.In a series of laboratory experiments, we assessed the predatory nature of the

native Irish amphipod, Gammarus duebeni celticus, and the introduced G. pulex,

towards the mayfly nymph Baetis rhodani. We also investigated alterations in

microhabitat use and drift behaviour of B. rhodani in the presence of Gammarus,

and indirect predatory interactions with juvenile Atlantic salmon, Salmo salar.

2.In trials with single predators and prey, B. rhodani survival was significantly

lower when Gammarus were free to interact with nymphs as than when Gammarus

were isolated from them. The invader G. pulex reduced the survival of B. rhodani

more rapidly than did the native G. d. celticus. Both Gammarus spp. were active

predators.

3.In `patch' experiments, B. rhodani survival was significantly lower both when G.

pulex and G. d. celticus were present, although the effect of the two Gammarus

species did not differ. Again, active predation of nymphs by Gammarus was

observed. Significantly more nymphs occurred on the top and sides of a tile, and

per capita drifts were significantly higher, when Gammarus were present. Baetis

rhodani per capita drift was also significantly higher in the presence of the

introduced G. pulex than with the native G. d. celticus.

4.Gammarus facilitated predation by salmon parr of B. rhodani by significantly

increasing fish-nymph encounters on exposed gravel and in the drift. There were no

differential effects of the two Gammarus spp. on fish -B. rhodani encounters or

consumption.

5.We conclude that Gammarus as a predator can have lethal, nonlethal, direct and

indirect effects in freshwaters. We stress the need for recognition of this predatory

role when assigning Gammarus spp. to a `Functional Feeding Group'.

жүктеу/скачать 1.21 Mb.

Достарыңызбен бөлісу: