Seasonal Changes

Seasonal Changes

It is clear from the discussion on the effects of light and temperature that there are seasonal changes in the aquatic flora as a whole.

This applies even in springs at constant temperatures and temperate climates where the winter flora is dominated by Diatoms and the summer flora by Chlorophytes, Cyanophytes, and Rhodophytes.

Light is therefore certainly involved. Various lists of times of occurrence of different algal species are available. Usually Diatoms dominate these lists of species and in stony streams and rivers, they are also the most abundant forms.

In streams that are dominated by melt water floods and cold winters, the seasonal cycle may become truncated by physical conditions.

For instance, in the west, the scouring actions of the floods in May and June almost clean the stones and it is late July before recovery is evident leading to a buildup of Diatoms and other algae.

During December and January, however, a decline caused by anchor and frazil ice although the number of Diatoms increased a little in early spring, they were swept away by the melt water. On stony or other solid substrate, there is a fairly clear annual cycle and in running water, the actual nature of the substratum is apparently not of great importance for many species except in respect to stability.

It can also often be seen that algae are arranged on stones and other fixed objects in a definite way in relation to the current. This is nicely shown in Figure ___ (from Hem pg 75), The illustration of the distribution of algal species on variously submerged stones.

Studies of algal colonization of substrate show heavier colonization on the upstream and downstream sides than laterally. This is undoubtedly due to the small differences in local conditions.

The upstream face of a stone is the one most likely to receive disseminates carried by the current, and it also has a thin zone of dead water because of the splitting of the main stream of the current as it passes each side of the stone. There is also a much larger dead zone of water on the downstream side, whereas the only dead water on the sides was the boundary layer. Such observations explain, at least in part, why some local distributions occur and why some species are largely confined to upstream faces in certain situations and do not alsooccur on downstream faces.

Next Topics…

XXX
XXY
XXZ



Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

...more from Dr. Gordon Snyder
Dr. Gordon Snyder on Google


Phone: (206) 440-3008 • info@sciencefaircenter.com

Home | Site Map | Privacy Policy | Customer Service | Contact Us | Links

Visa Master Card AmEx PayPal

Please visit our family of websites

School water science fair projects
ScienceFairWater.com
ScienceFairCenter.com online store
ScienceFairCenterEnvironmental.com online store
SciencefairCenterWater.com online store
HydroPodnics.com online store
Watercenter.org

Scrapbook card making paper crafts
Urbanscrapbooker.com
Urbanscrapbooker.com online store
Scrapbook supplies donation progrm
Scrapbooking - card making classes
Scrapbook newsletter
Scrapbook store map contact us
Urban Scrapbooker blog
Urban Scrapbooker videos

Whales Without Borders
WhalesWithoutBorders.com
WhalesWithoutBorders.org
WhalesWithoutBorders.info
WhalesWithoutBorders.net

Water filters, water test kits, water equipment
Watercenter.com
Watercenterfilters.com
Watercenter.net
Battle Bottled Water Info
Water Logged Blog

Music, music composition, restore vinyl records
BarrySebastian.com
SebastionAndTheDeepBlue.com
Dyslexichiphop.com
Cleanlp.com
Cleanlps.com online store
JonesTechServices.com
spam prevention

All our websites are different...
Website created by Gordon Snyder and hosted by: synergos.com
Last updated on:
Family Friendly Website Safe Surf Sites Water Friendly Website Award Internet Rating Content Assoc.
www.sciencefairwater.com © 1998 - 2013 Gordon Snyder & Consultants, Inc., All rights reserved .