Tag Archives: ecology


Chapter 7, Estuaries, in: Introduction to the Biology of Marine Life (9th Edition)

The Chesapeake Bay, San Francisco Bay, Great South Bay, Tampa Bay, Puget Sound, and the Mississippi River Delta, the Hudson River Bay, Columbia River and Willapa Bay in Oregon, are among 100 bodies of water designated as estuaries in the US. Over 1/3 of the US population lives within the drainage basins of these estuaries.

Types of estuaries:
a. Coastal plan estuaries;
b. Bar built estuaries;
c. Coastal lagoons;
d. Deltas;
e. Tectonic estuaries;
f. Fjords.

Because of the patterns of freshwater and seawater mixing, there is an inward flow of nutrient rich seawater along the bottom of th estuary and a net outward flow at the surface, creating an estuarine upwelling. The time necessary for the total volume of water in an estuary to be replaced is called the flushing time.

The body fluids of osmotic conformers fluctuate to remain isotonic with the water. Most estuarine animals are stenohaline, tolerating exposure only to limited salinity ranges. A few species are euryhaline, capable of withstanding a wide range of salinity. Continue reading

April 22: international Earth Day, not today?

Today, April 22, Earth Day is celebrated mainly in the US. The day originates in the early 70s as a public demonstration of popular political support for an environmental agenda and was organized for the first time in 1970. The day’s date is somewhat arbitrary but approximates Arbor Day. Equinoctial Earth Day is celebrated in most countries on the day that the sun passes the equator and night has equal length as day. The vernal equinox (or spring equinox) marks the beginning of astronomical spring. It occurs around 20 March in the Northern Hemisphere, and around 23 September in the Southern Hemisphere.

With science taking the role of religion as the leading guide in Truth and the Enlightment of Mankind the celebration of the beginning of Spring has only folkloristic meaning. And with a global environment being under threat of the uncontrolled and gratuitous dumping of industrial waste, today’s Earth Day is of greater importance than the equinoctial celebration. Allow a minute of your time and breathe in some information on the beauty and diversity of the planet at the links below.

World Wildlife Foundation (WWF)
National Audubon Society
The Nature Conservancy
National Arbor Day Foundation
United Nations Environment Program
Earth Day – US Government Portal