CHARAPHYTES


The charaphytes are the largest and most easily recognized algae in the Connecticut River; they are also among the most interesting. These algae grow attached to mud substrates in the river, usually about 2-3 feet (0.5-1 meter) beneath the surface.

They are relatively common in the stretch of the river between the French King Gorge and the New Hampshire state line. Charaphytes are useful biomarkers for cleaner waters.

Paradoxically the most common type of river pollution is by agents that enhance the growth of plants. In terrestrial ecosystems, plant growth is often limited by that availability of soil nutrients containing nitrogen and phosphorous. In the river, a key factor that greatly influences the amount and type of algal growth is phosphorous. Phosphorous enters the Connecticut River from three general sources: untreated sewage, the outfalls of sewage and wastewater treatment facilities, and agriculture.

Waters with low phosphorous levels (less than 20 microgm/l) allow the growth of charaphytes. Species of this group of macroscopic algae occur in the Connecticut River in western Massachusetts in Northfield, where they are relatively common.

Stretches of the river with high phosphorous loading lack charaphytes; another group of algae flourish -- the filamentous green algae.

These plants can develop enormous masses carpeting the river bottom.

Biologically the charaphytes are incredibly interesting. A considerable amount of morphological and molecular data support the hypothesis that the "Land Plants" (mosses, liverworts, pteridophytes, gynmosperms and angiosperms) and the charaphytes are closely related evolutionarily. The earliest land plants probably evolved from a charaphyte-like ancestor, perhaps 450-470 million years ago! Imagine what the world would have been like if this evolutionary step from charaphyte to land plant never occurred; without land plants to provide food, land animals (amphibians, reptiles, mammals, us) would have never evolved! You wouldn't be reading this page.

General Description - For inquiries contact Sona Dolan, phycologist (student of algae) living in Sunderland, MA. She is a volunteer researcher in the Biology Department at the University of Massachusetts Amherst and a member of the International Phycological Society. She has been studying marine algal taxonomy including cyanobacteria since she was an undergraduate student. Her Master's and Ph.D. work is on red algal taxonomy and systematics.

The charaphytes are macroscopic algae; their body plan is based upon erect stem-like branches and whorls of secondary branches. The main axis is composed of two types of cells, long internode cells alternating with much shorter node cells from which whorls of laterals arise.

The main axis is attached to the soft substratum by numerous by numerous branched rhizoids. Although vegetative growth from the node cells is often prolific, sexual reproduction is common. There are both monoecious (both male and female sex organs on one individual) and dioecious (males and females) species. The sex organs develop as offshoots from the nodes.

The conspicuous antheridia (male sex organs) are spherical and bright orange or yellow when mature. The antheridium releases spermatogeous filaments which contain sperm cells. Large numbers of sperm are released from filamentous cells within these bodies.

The female organs, or oogonia, are unlike those of any other alga. The oogonia are large, ovoid, or subglobose cells containing a single egg and surrounded by a series of helically twisted cells capped at their apex by one or two rings of crown cells. After fertilization, the oospore wall darkens and the surrounding threads become calcified and silicified. The oospores normally become detached and later germinate to produce the next generation. The calcified oospore cells fossilize easily and remains of charophytes have been found in rocks 400 million years old.

Two genera of charaphytes have been found in the Connecticut River: Chara and Nitella.

For more information on land plant evolution, see:
Graham, L.E. (1993). Origin of Land Plants. John Wiley & Sons, Inc., New York.