ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

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Electronic Resource

Residential expansion as a continental threat to U.S. coastal ecosystems (2000)

Bartlett, J. G. ; Mageean, D. M. ; O'Connor, R. J.

Springer

Population and environment 21 (2000), S. 429-468

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ISSN: 1573-7810

Source: Springer Online Journal Archives 1860-2000

Topics: Energy, Environment Protection, Nuclear Power Engineering , Sociology

Notes: Abstract Spatially extensive analysis of satellite, climate, and census data reveals human-environment interactions of regional or continental concern in the United States. A grid-based principal components analysis of Bureau of Census variables revealed two independent demographic phenomena, α-settlement reflecting traditional human settlement patterns and β-settlement describing relative population growth correlated with recent construction in non-agricultural areas, notably in coastal, desert, and “recreational” counties and around expanding metropolitan areas. Regression tree analysis showed that β-settlement was differentially associated with five distinct combinations of seasonality, summer heat or cool, intensity of agriculture, and extent of “barren” land. Beta-settlement was greatest in coastal and desert areas, and coincided with national concentrations of threatened and endangered species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02436749

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Niche breadth in Bryozoa as a test of competition theory (1975)

O'CONNOR, R. J. ; BOADEN, P. J. S. ; SEED, R.

[s.l.] : Nature Publishing Group

Nature 256 (1975), S. 307-309

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] Intraspecific competition should result in an increase in the range of a resource spectrum used by a species, as at high population levels the advantages to any individual of being at the competition-free optimum of a resource gradient are offset by the intense intraspecific competition found there ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/256307a0

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Prey depletion and foraging strategy in the Oystercatcher Haematopus ostralegus (1977)

O'Connor, R. J. ; Brown, R. A.

Springer

Oecologia 27 (1977), S. 75-92

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ISSN: 1432-1939

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The responses of a population of Oystercatchers to their own depletion of their prey, the edible cockle Cerastoderma edule, have been examined in Strangford Lough, Northern Ireland., Cockle stocks were severely depleted each winter as a result of predation by Oystercatchers and about half the birds present in October in the main study area had left by March: the reduction was greater when the initial population of Oystercatchers was high than when it was low. Oystercatchers were initially widespread around the Lough but tended to aggregate by January into a few good sites. Within each site annual differences in the location of feeding effort were correlated with year to year variation in the location of second winter cockles. Within the feeding areas in a bay the birds apparently hunted in the short-term on the basis of expectation, ceasing to crop, the densest cockle beds once an average yield for the area has been removed; this yield was apparently estimated from the local density of the anvils on which captured cockles were broken open. This effect led to marginal areas being depleted of cockles more rapidly than high density areas, so that the birds gradually concentrated their hunting onto an increasingly restricted area of the bay. The birds initially took only second winter and larger cockles but by late winter cockle densities had fallen so much that smaller cockles were accepted: areas previously abandoned or unused for hunting were then economically viable because of the reduced expectations of the birds and were incorporated into the feeding areas. These results are seen as consistent with Royama's profitability theory.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00345686

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