The life form spectra showed 31 (39.74%) therophytes, 17 (21.79%) megaphanerophytes, 12 (15.38%) cryptophytes
, 11 (14.10%) nanophanerophytes, 5 (6.41%) hemicryptophytes and 2 (2.56%) chamaephytes (Table 2, Fig.
It was found that diatoms dominated phytoplankton biomass at all times (typically 50% or more of total phytoplankton biomass) followed by green algae (20 to 30%), cyanobacteria (10 to 20%), and cryptophytes
Riverine phytoplankton, consisting mostly of small-celled cryptophytes
and diatoms (Sobczak et al., 2002; Piirsoo et al., 2007), the latter often originating in periphyton, are easily assimilated by aquatic invertebrates, especially collector-gatherers and filter feeders (Webster et al., 1999).
Finally, free-living phytoplankton, including dinoflagellates, cryptophytes
, diatoms, and prymnesiophytes, show no effect of lowered pH (within a range of ~7.0-8.5) on growth rates (Berge et al., 2010), emphasizing the lack of algal growth sensitivity to high pC[O.sub.2] exposure.
El-Ghareeb and Rezk (1989) provided evidence that therophytes acquire dominance in less saline and more sandy habitats, while cryptophytes
and chamaephytes in more saline habitats.
The vegetation, thus affected, includes shrubs, geophytes, hemi- cryptophytes
, and annuals.
We considered only the life-form categories originally proposed by Raunkiaer: phanerophytes, chamaephytes, hemicryptophytes, cryptophytes
, and therophytes) tend to be under-represented among collections undertaken during just a single period.
Proposed by Raunkiaer (1934), the system classifies plants according to forms used to protect their perennating buds during unfavorable seasons, and groups them into five main classes: therophytes, cryptophytes
, hemicryptophytes, chamaephytes and phanerophytes, according to their different resistance strategies to environmental conditions.
The rest was taken up by cryptophytes
, mainly Cryptomonas spp.
Availability of cryptophytes
(only geophytes) and therophytes confirms the anthropogenic disturbance of the substrate.