Details

Autor(en) / Beteiligte

• Wall, David
• Dale, Barrie
• Lohmann, G.P.
• Smith, Woollcott K.

Titel

The environmental and climatic distribution of dinoflagellate cysts in modern marine sediments from regions in the North and South Atlantic Oceans and adjacent seas

Ist Teil von

• Marine micropaleontology, 1977-01, Vol.2, p.121-200

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

1977

Link zum Volltext

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• Quantitative treatments of 168 dinoflagellate cyst assemblages from modern marine sediments were used to decipher the salient environmental and climatic features of the distribution of common living cyst-based taxa. Surface sediment samples were studied by routine palynological methods from estuarine, continental shelf, slope and rise zones, and abyssal plains between latitudes 62°N and 27°S within fourteen geographic regions of the North and South Atlantic Oceans, the Caribbean and Mediterranean Seas and from one region in the southeastern Pacific Ocean near Peru, to meet this general objective. The results were expressed as percentages of species present and statistically analyzed by multivariate Q-mode factor analysis, cluster analysis and by calculation of a diversity index, using pre-existing computerized routines. Inshore to offshore and latitudinal (climatic) variations in distribution were identified and they involved individual taxa, associations of species, species diversity and specimen densities (cysts per gram of sediment). They were related empirically to changing surface water environments above and this suggested that biologic-ecologic phenomena, which involve species-water type relationships for different taxa, combined with hydrodynamic (current) systems, are the most important factors that control cyst distribution in the bottom thanatocoenosis. However, geologic factors such as recycling of older specimens and outcroppings of relict Pleistocene-Early Holocene sediments exert their influence too. An ecologic classification for extant cyst-based species is proposed in the format of classical “plankton elements”. This format is dictated by the existence of dual trends (environmental and climatic) in cyst distribution. It is suggested that genesis of ecologic species-groups of this nature during evolution can be interpreted by or “predicted” from stability-predictability concepts as developed in contemporary ecologic work, if surface water masses are considered to represent unique hydrographic climates with innate stability and predictability characteristics. This concept of “hydroclimatic stability” is used to identify fossilizable living dinoflagellates as being environmentally adapted to unstable conditions around continental margins and comparable shallow-water environments around oceanic islands. In addition there is a tendency for the more stenotopic extant cyst-based taxa to be adaptively specialized towards more stable sectors of nearshore and offshore plankton environments which develop at the terminal and subterminal ends of temperature and salinity regimes or profiles. One taxonomic change is introduced: Planinosphaeridium choanum (Reid 1974) nov. comb. is proposed from the basionym Ataxiodinium choanum Reid 1974.