Iriberri J, Herndl G J
Department of Immunology, Microbiology and Parasitology, School of Sciences, University of the Basque Country, Bilbao, Spain.
Microbiologia. 1995 Sep;11(3):309-22.
Amorphous organic particles, ("marine snow"), are thought to play a vital role in the transfer of carbon and energy from the euphotic layers of the ocean to the deep sea bed. These particles are mainly derived from phytoplankton extracellular release. As 10 to 40% of the dissolved organic carbon consists of colloidal material, colloids may represent a prominent role in these transfer processes. These colloids adsorb charged molecules efficiently and can coagulate further to form the recently described transparent exopolymer particles and eventually the ubiquitous macroscopic marine snow. The other mechanism proposed leading ultimately to marine snow formation is inefficient top-down control of phytoplankton growth by zooplankton. In the senesce of the phytoplankton bloom the cell surface becomes sticky due to the release of polysaccharides, and single phytoplankton cells then aggregate. Subsequently these aggregates become densely colonized by auto- and heterotrophic microbes, but while the abundance of these microorganisms is from 2 to 4 orders of magnitude higher than in the ambient water, their growth rates are usually not significantly increased in the aggregates. In this review, the reasons for this conspicuous pattern are discussed and recently investigated novel types of particles and their significance in the light of oceanic carbon transfer are presented.
无定形有机颗粒（“海洋雪”）被认为在碳和能量从海洋真光层向深海海底的转移过程中起着至关重要的作用。这些颗粒主要来源于浮游植物的胞外释放。由于10%至40%的溶解有机碳由胶体物质组成，胶体可能在这些转移过程中发挥重要作用。这些胶体能够有效地吸附带电分子，并可进一步凝聚形成最近描述的透明胞外聚合物颗粒，最终形成无处不在的宏观海洋雪。另一种最终导致海洋雪形成的机制是浮游动物对浮游植物生长的自上而下控制效率低下。在浮游植物水华的衰老阶段，由于多糖的释放，细胞表面变得粘稠，单个浮游植物细胞随后聚集。随后，这些聚集体被自养和异养微生物大量定殖，但是，虽然这些微生物的丰度比周围水体高2至4个数量级，但它们在聚集体中的生长速率通常不会显著增加。在这篇综述中，讨论了这种显著模式的原因，并介绍了最近研究的新型颗粒及其在海洋碳转移方面的意义。
