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Divergent distributions of prey and predator, a fishing effect? (1995)

Hartmann, J. ; Probst, L.

Springer

Aquatic sciences 57 (1995), S. 106-118

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ISSN: 1420-9055

Keywords: Benthos ; fish ; vertical distribution ; predation risk ; selective fishing ; Lake Constance

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract To compare the vertical distributions of benthos and fish species of Upper Lake Constance (Bodensee), 552 benthos samples were taken with an Auerbach grab at four transects (10–250 m). An additional 54 samples (1–10 m) were collected elsewhere. Complementary data was taken from the literature. In winter, most fish feed on benthos, mainly chironomids, but in summer less than 5% do so. Formerly the bottom gill-netting aimed mainly at catchingCoregonus pidschian, but it now aims atPerca fluviatilis. Contrary to expectation, in winter the greatest abundance ofP. fluviatilis is much deeper (55 m) than that of its preferred food, i.e. chironomids (〈20 m). Comparably,C. pidschian also stayed deeper than its main food source (chironomids and mollusks).Lota lota, Salvelinus profundus andS. alpinus — unlike the unwanted cyprinids — also stay or stayed deeper than the attractive chironomids. It is argued that the fish reduce their “predation risk”, i.e. the risk of being gillnetted in the upper 50 m, by “selecting” the deeper less dangerous, but also less food-abundant habitat. Balancing predation risk against food abundance may have led to “survival of the deepest”.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00877379

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Conformational study of the 4,9-dihetero-(Z,Z)-cyclodeca-1,6-diene ring system; the mono- and di-benzo analogues (1990)

Kleinpeter, E. ; Hartmann, J. ; Schroth, W.

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 28 (1990), S. 628-634

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ISSN: 0749-1581

Keywords: 13C NMR ; 1H NMR ; 4,9-Dihetero-(Z,Z)-cyclodeca-1,6-dienes ; Ring inversion barriers ; Restricted rotation ; Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The dynamic 1H and 13C NMR spectra of a series of mono- and bis-annelated 4,9-dihetero-(Z,Z)-cyclodeca-1,6-dienes were obtained and are discussed with respect to ground-state conformers and the barriers to ring inversion, and to the restricted rotation about exocyclic partial C,N double bonds. The ten-membered rings are, with one exception, anancomeric chair conformers and interconvert via a combination of single bond rotations and bond angle bendings. Depending on the heteroatoms present, the series of decreasing barriers to ring inversion S 〉 NH 〉 O was obtained. Benzannelation decreases the free energy of activation of the same dynamic process owing to greater intramolecular transannular H,H interactions.

Additional Material: 4 Tab.