Disturbance of Opportunistic Small-Celled Phytoplankton in Lake Kinneret

Abstract EN

In spite of the chaotic dynamics of specific populations, similarity of annual species-abundance distributions was proven for phytoplankton assemblage during a “stable” period (1985–1994) of Lake Kinneret (Israel).

This similarity declined during the “extreme” years (1995–1999) that followed, characterized by explicit changes in the phytoplankton annual-succession pattern.

The rank-abundance distributions of species exhibit a pronounced difference between the taxonomically rich central region, producing the reliable assemblage backbone and highly variable tails of a few species.

Therefore, the distribution pattern comparison enhances the importance of ubiquitous small disturbances valuable for diagnostics.

Some phyla (in this case, Cyanophyta) were especially vulnerable to structural changes.

A simple disturbance index was constructed, based on opportunistic small-celled species.

The fine-structure disturbances, which can provide early-warning information, are discussed.