Zonneveld KA, Brune A, Willems H
Fachbereich 5-Geowissenschaften, Postfach 330440, D-28334, Bremen, Germany
Rev Palaeobot Palynol. 2000 Sep 1;111(3-4):197-223. doi: 10.1016/s0034-6667(00)00024-5.
To enhance the limited information available about the palaeo-ecological significance of calcareous dinoflagellates, we have studied their lateral distribution in surface sediments of the equatorial and south Atlantic between 13 degrees N and 36 degrees S. Calcareous dinoflagellate cysts appear to be widely distributed throughout the studied area. In the surface sediments, concentrations (cyst per gram dry sediment) of the vegetative stage Thoracosphaera heimii are generally higher than that of the (presumably) calcareous resting cysts. Distribution patterns in surface sediments of Orthopithonella granifera (Fütterer) Keupp and Versteegh, Rhabdothorax spp. Kamptner., Sphaerodinella albatrosiana (Kamptner) Keupp and Versteegh S. albatrosiana praratabulated, Sphaerodinella tuberosa var. 1 (Kamptner) Keupp and Versteegh and S. tuberosa var. 2 and the ratios between these species have been compared with temperature, salinity, density and stratification gradients in the upper water column. Rhabdothorax spp. is characteristically present in sediments of more temperate regions characterized by high seasonality. Dinoflagellates producing these cysts are able to tolerate high nutrient concentrations, and mixing of the water column. S. albatrosiana is abundant in regions characterized by high sea surface temperatures and oligotrophic surface water conditions. In contrast, the distribution of S. tuberosa var. 2 is negatively related to temperature. The other cyst species did not show a characteristic pattern in relation to the studied environmental gradients.The ratio of Sphaerodinella tuberosa var. 2 to Orthopithonella granifera can be used for reconstructing the presence of stratification in the upper 50m of the water column, whereas the ratios of S. tuberosa var. 2 to Sphaerodinella albatrosiana and of O. granifera to Rhabdothorax spp. might be used for palaeotemperature reconstructions. Calcareous dinoflagellate cysts are abundant in oligotrophic areas and may be useful for the reconstruction of palaeoenvironmental conditions.
为了增加有关钙质甲藻古生态意义的有限信息，我们研究了它们在北纬13度至南纬36度之间赤道和南大西洋表层沉积物中的横向分布。钙质甲藻囊孢似乎广泛分布于整个研究区域。在表层沉积物中，营养阶段的海氏胸球藻（Thoracosphaera heimii）的浓度（每克干沉积物中的囊孢数）通常高于（可能）钙质休眠囊孢的浓度。对粒形直皮藻（Orthopithonella granifera (Fütterer) Keupp and Versteegh）、横纹胸球藻属（Rhabdothorax spp. Kamptner.）、白腹球藻（Sphaerodinella albatrosiana (Kamptner) Keupp and Versteegh）、准表格白腹球藻（S. albatrosiana praratabulated）、瘤状球藻变种1（Sphaerodinella tuberosa var. 1 (Kamptner) Keupp and Versteegh）和瘤状球藻变种2的表层沉积物分布模式以及这些物种之间的比率，与上层水柱中的温度、盐度、密度和分层梯度进行了比较。横纹胸球藻属通常出现在季节性较强的温带地区的沉积物中。产生这些囊孢的甲藻能够耐受高营养浓度和水柱混合。白腹球藻在以高海表温度和贫营养表层水条件为特征的区域丰富。相比之下，瘤状球藻变种2的分布与温度呈负相关。其他囊孢物种在与所研究的环境梯度相关方面未显示出特征模式。瘤状球藻变种2与粒形直皮藻的比率可用于重建水柱上部50米分层的存在情况，而瘤状球藻变种2与白腹球藻的比率以及粒形直皮藻与横纹胸球藻属的比率可能用于古温度重建。钙质甲藻囊孢在贫营养区域丰富，可能有助于重建古环境条件。
