Assemblage structures and distribution patterns of larval fishes and paralarval cephalopods were examined in September 1998 at Great Meteor Seamount, an isolated seamount located in the subtropical ...eastern North Atlantic. Early life stages of fish (
n=18555) and cephalopods (
n=1200) were collected at 23 stations with a multiple opening–closing net, in seven discrete depth strata from 290
m depth (close to the seamount plateau) to the surface. Oceanic species dominated in both taxonomic groups. A peak in diversity was observed at an intermediate depth, in the 100–150
m water layer. Direct and indirect gradient analyses showed distinct species assemblages in the upper and lower part of the water column, separated by approximately 150
m. The division was statistically significant, although a considerable overlap between species was also observed. Above the summit, vertical gaps were found in the distributions of the deeper assemblages, likely caused by increased predation pressure by benthopelagic fish. Horizontal distribution patterns of fish and cephalopods were similar and corresponded to the structure of closed circulation cells detected above the flanks and the flat plateau area. Fish assemblages were significantly different between the inner and outer seamount regime, which was approximately separated by the 1500
m depth contour. Differences in the taxonomic composition of cephalopods were less pronounced; for only one cephalopod species could a direct association with the seamount be assumed. The study indicates a significant retention potential at the seamount that facilitates local recruitment of resident stocks and generates self-sustainable populations isolated from the continental shelf and oceanic islands.
One may postulate that man's interest in fish emerged as soon as he was able to express his thoughts and notions as fish, among other animals, were subject of early communications. These were ...transmitted first by drawings, later by inscriptions and in writings. It was but much later that fishes began to occupy man's interest as objects of science. Aristotle's treatises on 'History of Animals' is the first known document dealing with fish as a zoological object. No earlier than in the 16 super(th) century fish regained the interest of learned men, among these Olaus Magnus (1490 -1557), Gregor Mangolt (1498-1576), Guillaume Rondelet (1507-1557), Pierre Belon (1512-1564), Hippolyto (Ippolito) Salviani (1513-1572) and, above all, Conrad Gesner (1516-1565). The 17 super(th) and more so the 18 super(th) century is known as the period of Enlightenment. Respect must be paid to three pioneers in this field, i.e. Francis Willughby (1635-1672), Peter Artedi (1705-1735), and Marc Elieser Bloch (1723-1799) who became clearly aware that the class of fish consists of species which may be classified and typically described as such. After the species concept had been embodied in the scientific way of thinking by Linne, a tremendous expansion of activities emerged in the field of ichthyology. Many different regions and aquatic localities were researched and described by their fish fauna. In the 19 super(th) century until the beginning of the 20 super(th) century ichthyology was dominated by disciplines such as taxonomy, descriptive biology and classification. This was followed by more advanced physiological, ecological and ethological research on fishes, yielding quite new insights in modern ichthyology. Nowadays research is largely orientated towards aspects of applied ichthyology, i.e. fishery biology and aquaculture. Fish and ichthyological records, respectively, proceeded discontinuously and recurred periodically. Many scientific questions on fish still remain unsolved, allowing ichthyologists of today to continue working on this highly diverse and species-rich group of vertebrates. In the future new challenges in ichthyology will be emerging in the fields of a) taxonomy, b) evolution and systematics, c) population biology, d) ecology, e) studying unknown regions for their fish fauna, f) expanding and improving an international global catalogue of fishes, g) exploring and analysing not yet recognized literature.Original Abstract: Moglo bi se zaklju citi da je covjekovo zanimanje za ribe iskrsnulo cim je covjek postao sposoban za izrazavanje pojmova i misli, jer riba je, zajedno sa ostalim zivotinjama, bila tema rane ljudske komunikacije. Prvo su ove misli bile izrazene kroz crteze, a kasnije kroz simbole i pisani tekst. Ribe su postale predmetom znanstvenog istrazivanja znatno kasnije. Aristotelovo djelo 'Povijest zivotinja' je prvi poznati zapis koji se bavi ribama kao objektom znanosti o zivotinjama. Tek u 16. stoljecu pitanje riba je ponovo zaokupilo zanimanje prosvijecenog covjeka, izmedju ostalih Olaus Magnusa (1490-1557), Gregora Mangolta (1498-1576), Guillaume Rondeleta (1507-1557), Pierre Belona (1512-1564), Hippolyto (Ippolito) Salviania (1513-1572), a povrh svega Conrad Gesnera (1516-1565). Sedamnaesto, a posebno osamnaesto stoljece, poznata su kao razdoblja prosvjetljenja. Posebna zasluga se u tom vremenu mora odati trojici za cetnika ihtiologije, Francis Willughbyu (1635-1672), Peter Artediju (1705-1735), te Marc Elieser Blochu (1723-1799), koji su vec tada bili svjesni da se unutar klase riba mogu jasno i precizno odredjivati i opisivati vrste u svom punom smislu. Nakon sto je Carl von Linne znanstveno opisao koncept vrste, obimna istrazivanja su zapo cela unutar ihtiologije te ujedno i doprinjela utemeljenju ihtiologije kao posebne znanosti. Brojni predjeli te brojne vodene povrsine su tada istrazene s gledista sastava njihove ihtiofaune. Tijekom 19. stoljeca, pa sve do po cetka 20. stoljeca, unutar ihtiologije posebna se pozornost posvetila taksonomiji, opisnoj biologiji te klasifikaciji. Kasnije je slijedilo razdoblje zna cajnog istrazivanja riba sa gledista fiziologije, ekologije i etologije, sto je stvorilo sasvim nove poglede i vidike prema modernoj ihtiologiji. Danas su istrazivanja uglavnom usmjerena prema primjenjenoj ihtiologiji, odnosno takozvanoj ribarstvenoj biologiji i akvakulturi. Sakupljanje ihtioloskih podataka se nastavlja bez prekida, a odredjena nerijesena pitanja se vracaju s vremena na vrijeme. Mnoge znanstvene nedoumice vezane uz ribe jos uvijek ostaju, u nekim segmentima, neodgovorene, uslijed cega danasnji ihtiolozi i dalje nastavljaju istrazivati ovu izuzetno raznoliku grupu kraljesnjaka. Buduci izazovi u ihtiologiji su svakako podru cja: a) taksonomije, b) evolucije i sistematike, c) populacijske biologije, d) ekologije, e) istrazivanja raznih lokaliteta neistrazenih po pitanju faune riba, f) rada na prosirenju i usavrsavanju medjunarodnih kataloga riba, i g) istrazivanja i analiziranja jos uvijek neprepoznate znanstvene literature.
Moglo bi se zaključiti da je čovjekovo zanimanje za ribe iskrsnulo čim je čovjek postao sposoban za izražavanje pojmova i misli, jer riba je, zajedno sa ostalim životinjama, bila tema rane ljudske ...komunikacije. Prvo su ove misli bile izražene kroz crteže, a kasnije kroz simbole i pisani tekst. Ribe su postale predmetom znanstvenog istraživanja znatno kasnije. Aristotelovo djelo “Povijest životinja” je prvi poznati zapis koji se bavi ribama kao objektom znanosti o životinjama. Tek u 16. stoljeću pitanje riba je ponovo zaokupilo zanimanje prosvijećenog čovjeka, izmedju ostalih Olaus Magnusa (1490-1557), Gregora Mangolta (1498–1576), Guillaume Rondeleta (1507–1557), Pierre Belona (1512–1564), Hippolyto (Ippolito) Salviania (1513–1572), a povrh svega Conrad Gesnera (1516-1565). Sedamnaesto, a posebno osamnaesto stoljeće, poznata su kao razdoblja prosvjetljenja. Posebna zasluga se u tom vremenu mora odati trojici začetnika ihtiologije, Francis Willughbyu (1635–1672), Peter Artediju (1705–1735), te Marc Elieser Blochu (1723–1799), koji su već tada bili svjesni da se unutar klase riba mogu jasno i precizno određivati i opisivati vrste u svom punom smislu. Nakon što je Carl von Linné znanstveno opisao koncept vrste, obimna istraživanja su započela unutar ihtiologije te ujedno i doprinjela utemeljenju ihtiologije kao posebne znanosti. Brojni predjeli te brojne vodene površine su tada istražene s gledišta sastava njihove ihtiofaune. Tijekom 19. stoljeća, pa sve do početka 20. stoljeća, unutar ihtiologije posebna se pozornost posvetila taksonomiji, opisnoj biologiji te klasifikaciji. Kasnije je slijedilo razdoblje značajnog istraživanja riba sa gledišta fiziologije, ekologije i etologije, što je stvorilo sasvim nove poglede i vidike prema modernoj ihtiologiji. Danas su istraživanja uglavnom usmjerena prema primjenjenoj ihtiologiji, odnosno takozvanoj ribarstvenoj biologiji i akvakulturi. Sakupljanje ihtioloških podataka se nastavlja bez prekida, a određena neriješena pitanja se vraćaju s vremena na vrijeme. Mnoge znanstvene nedoumice vezane uz ribe još uvijek ostaju, u nekim segmentima, neodgovorene, uslijed čega današnji ihtiolozi i dalje nastavljaju istraživati ovu izuzetno raznoliku grupu kralješnjaka. Budući izazovi u ihtiologiji su svakako područja: a) taksonomije, b) evolucije i sistematike, c) populacijske biologije, d) ekologije, e) istraživanja raznih lokaliteta neistraženih po pitanju faune riba, f) rada na proširenju i usavršavanju međunarodnih kataloga riba, i g) istraživanja i analiziranja još uvijek neprepoznate znanstvene literature.
One may postulate that man’s interest in fish emerged as soon as he was able to express his thoughts and notions as fish, among other animals, were subject of early communications. These were ...transmitted first by drawings, later by inscriptions and in writings. It was but much later that fishes began to occupy man’s interest as objects of science. Aristotle’s treatises on “History of Animals” is the first known document dealing with fish as a zoological object. No earlier than in the 16th century fish regained the interest of learned men, among these Olaus Magnus (1490 –1557), Gregor Mangolt (1498–1576), Guillaume Rondelet (1507–1557), Pierre Belon (1512–1564), Hippolyto (Ippolito) Salviani (1513–1572) and, above all, Conrad Gesner (1516–1565). The 17th and more so the 18th century is known as the period of Enlightenment. Respect must be paid to three pioneers in this field, i.e. Francis Willughby (1635–1672), Peter Artedi (1705–1735), and Marc Elieser Bloch (1723–1799) who became clearly aware that the class of fish consists of species which may be classified and typically described as such. After the species concept had been embodied in the scientific way of thinking by Linné, a tremendous expansion of activities emerged in the field of ichthyology. Many different regions and aquatic localities were researched and described by their fish fauna. In the 19th century until the beginning of the 20th century ichthyology was dominated by disciplines such as taxonomy, descriptive biology and classification. This was followed by more advanced physiological, ecological and ethological research on fishes, yielding quite new insights in modern ichthyology. Nowadays research is largely orientated towards aspects of applied ichthyology, i.e. fishery biology and aquaculture. Fish and ichthyological records, respectively, proceeded discontinuously and recurred periodically. Many scientific questions on fish still remain unsolved, allowing ichthyologists of today to continue working on this highly diverse and species-rich group of vertebrates. In the future new challenges in ichthyology will be emerging in the fields of a) taxonomy, b) evolution and systematics, c) population biology, d) ecology, e) studying unknown regions for their fish fauna, f) expanding and improving an international global catalogue of fishes, g) exploring and analysing not yet recognized literature.
Moglo bi se zaključiti da je čovjekovo zanimanje za ribe iskrsnulo čim je čovjek postao sposoban za izražavanje pojmova i misli, jer riba je, zajedno sa ostalim životinjama, bila tema rane ljudske komunikacije. Prvo su ove misli bile izražene kroz crteže, a kasnije kroz simbole i pisani tekst. Ribe su postale predmetom znanstvenog istraživanja znatno kasnije. Aristotelovo djelo “Povijest životinja” je prvi poznati zapis koji se bavi ribama kao objektom znanosti o životinjama. Tek u 16. stoljeću pitanje riba je ponovo zaokupilo zanimanje prosvijećenog čovjeka, izmedju ostalih Olaus Magnusa (1490-1557), Gregora Mangolta (1498–1576), Guillaume Rondeleta (1507–1557), Pierre Belona (1512–1564), Hippolyto (Ippolito) Salviania (1513–1572), a povrh svega Conrad Gesnera (1516-1565). Sedamnaesto, a posebno osamnaesto stoljeće, poznata su kao razdoblja prosvjetljenja. Posebna zasluga se u tom vremenu mora odati trojici začetnika ihtiologije, Francis Willughbyu (1635–1672), Peter Artediju (1705–1735), te Marc Elieser Blochu (1723–1799), koji su već tada bili svjesni da se unutar klase riba mogu jasno i precizno određivati i opisivati vrste u svom punom smislu. Nakon što je Carl von Linné znanstveno opisao koncept vrste, obimna istraživanja su započela unutar ihtiologije te ujedno i doprinjela utemeljenju ihtiologije kao posebne znanosti. Brojni predjeli te brojne vodene površine su tada istražene s gledišta sastava njihove ihtiofaune. Tijekom 19. stoljeća, pa sve do početka 20. stoljeća, unutar ihtiologije posebna se pozornost posvetila taksonomiji, opisnoj biologiji te klasifikaciji. Kasnije je slijedilo razdoblje značajnog istraživanja riba sa gledišta fiziologije, ekologije i etologije, što je stvorilo sasvim nove poglede i vidike prema modernoj ihtiologiji. Danas su istraživanja uglavnom usmjerena prema primjenjenoj ihtiologiji, odnosno takozvanoj ribarstvenoj biologiji i akvakulturi. Sakupljanje ihtioloških podataka se nastavlja bez prekida, a određena neriješena pitanja se vraćaju s vremena na vrijeme. Mnoge znanstvene nedoumice vezane uz ribe još uvijek ostaju, u nekim segmentima, neodgovorene, uslijed čega današnji ihtiolozi i dalje nastavljaju istraživati ovu izuzetno raznoliku grupu kralješnjaka. Budući izazovi u ihtiologiji su svakako područja: a) taksonomije, b) evolucije i sistematike, c) populacijske biologije, d) ekologije, e) istraživanja raznih lokaliteta neistraženih po pitanju faune riba, f) rada na proširenju i usavršavanju međunarodnih kataloga riba, i g) istraživanja i analiziranja još uvijek neprepoznate znanstvene literature.
In comparison with a relatively uniform landscape organisms in a complex one have to cope with a distinctly higher number of problems. On the one hand, the irregular habitat pattern may be inducive ...to higher biodiversity, on the other isolation of habitats may result in a decrease in species numbers, if extinction is not compensated by immigration. In fractal landscape models, the number of species coexisting in microsites increased up to the fractal dimension of 2.75, but decreased with higher dimensions (Palmer 1992). Studies on ground beetles in the Netherlands showed a significantly higher proportion of species with high migration potentials in small habitats than in large ones (Vries et al. 1996). In stressed habitats an opposite effect might develop. Thus, Fahrig and Jonson (1998) found an increasing species richness in alfalfa fields with increasing isolation.
In diverse landscapes the quality of habitat fringes is, therefore, important for the interactions of habitats through species and the species richness of the habitats. Species interacting between different habitats can also influence ecosystem functions, e.g. seed dispersal or fructification of plants. For the pollinator–plant interaction Steffan-Dewenter and Tscharnke (1999) found that the proportion of large bees and bumblebees was higher in small habitats than in large habitats, which was attributed to the better flying ability of the larger species.
Borders between ecosystems (ecotones) may either serve as guidelines for migrating animals or as barriers that inhibit the dispersion of species. Corridors between ecosystems are generally regarded as structural prerequisites to optimize the migration into isolated habitats. However, corridors with suboptimal living conditions are only used by a few species (Collinge 2000) and only over short distances (Haas 1995). Furthermore, the interactions between habitats depend on their sink or source qualities (Cornelsen et al. 1993; Irmler et al. 2000).
Production of antihydrogen Baur, G.; Boero, G.; Brauksiepe, A. ...
Physics letters. B,
02/1996, Letnik:
368, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Results are presented for a measurement for the production of the antihydrogen atom
H
0 ≡
p
e
+
, the simplest atomic bound state of antimatter.
A method has been used by the PS210 collaboration at ...LEAR which assumes that the production of
H
0
is predominantly mediated by the e
+e
−-pair creation via the two-photon mechanism in the antiproton-nucleus interaction. Neutral
H
0
atoms are identified by a unique sequence of characteristics. In principle
H
0
is well suited for investigations of fundamental CPT violation studies under different forces, however, in our investigations we concentrate on the production of this antimatter object, since so far it has never been observed before.
The production of 11 antihydrogen atoms is reported including possibly 2±1 background signals, the observed yield agrees with theoretical predictions.
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