Environmental Engineering Reference
In-Depth Information
•
Kingdom Protista
•
Protozoans
•
Algae
•
Division Rhodophyta—red algae
•
Division Charophyta—desmids and stonewarts
•
Division Chrytophyta—chryptomonads
•
Division Euglenophyta—euglenoids
•
Division Phaeophyta—brown algae
•
Division Chrysophytes—chrosophytes
•
Division Haptophyte
•
Division Bacillariophyta—diatoms
•
Division Dinophyta—dinolagellates
•
Division Chlorophyta—green algae
•
Plasmodial slime molds
The point is that these groups (blue-green, brown algae, green algae, and diatoms) do not repre-
sent individual organisms or groups, but rather vast and diverse assemblages of organisms including
thousands of species, which do, however, share some common characteristics. Also, note that with
the possible exception of species, each of the classiication ranks (and the placement of organisms in
those ranks) is subjective, and may vary between references. So, for example, in Reynold's (2006)
The Ecology of Phytoplankton
, rather than divisions, the major groups of eukaryotic algae are sub-
divided into phyla (e.g., phylum Bacillariophyta).
One interesting question is why are there so many different types of phytoplankton or so much
species diversity? In a terrestrial environment, species diversity is often driven by the availabil-
ity of a variety of specialized ecological niches (places organisms may live and roles they may
take). However, for phytoplankton, there is water, light, and nutrients. That is, all plankton require,
essentially, is the same nutrients, and all water appears to be the same, so how can any diversity
be supported? This is what Hutchinson, in a 1961 paper, called the “paradox of the plankton”
(Hutchinson 1961). So, what is the answer? As Hutchinson stated in that seminal paper “Perhaps
it is, of course, possible that some people with greater insight might have seen further into the
problem of the plankton …, but for the moment I am content … of presenting that problem to you.”
15.3.1.1.1.1 Algae (Prot ist a)
•
Rhodophyta—Red Algae: Red algae are primarily (96%) marine organisms, and most
seaweeds are members of this group. They are typically attached algae. None of the red
algae is planktonic and few genera are found in freshwater (Wetzel 2001). They are red
because of the presence of the pigments phycoerythrin and phycocyanin, also found in
Cyanobacteria, which relects red light and absorbs blue light and masks the other pig-
ments (e.g., chlorophyll-a; Cole and Sheath 1990; Wilson 2000). Being able to absorb blue
light is a competitive advantage since blue light penetrates to greater depths than the light
of longer wavelengths. There are some freshwater species and Prescott (1962) lists some
species found in the Great Lakes. However, most commonly, the freshwater forms of these
algae are found in cold and fast-running streams.
•
Charophyta—Stonewarts: These algae can be unicellular or multicellular and commonly
occur in freshwater, primarily in slow-moving or standing water. These algae are commonly
anchored on muddy or sandy substrates or hard limestone streambeds (Bold and Wynne 1985).
The stonewarts commonly become encrusted with carbonates, hence their common name.
•
Division Chrytophyta—Chryptomonads: Chryptomonads are typically very small, unicel-
lular, mobile (with two lagella) phytoplankton found in almost any marine or freshwa-
ter environment, with the greatest diversity in temperate lakes (Suthers and Rissik 2009;
Search WWH ::
Custom Search