Right
This morning I want to give you a brief introduction to a different kind of habitat American salt marshes And then we will examine a particular inhabitant of the marsh the horseshoe crab
Okay so what are the defining features of a salt marsh to begin with
Well salt marshes are found on the coast in various parts of the USA They are really areas between land and water Obviously these are very wet areas and the salinity that is the amount of salt in the water ranges from ocean strength to almost fresh in other words very low indeed
And the salt marshes are affected by daily changes in sea levels The sea might wash in over them as frequently as twice a day so the habitat is constantly changing The amount of salt in the water rises and falls as does the depth and warmth of the water

We will be having a detailed look at the horseshoe crab in a moment but marshes provide plentiful food for other creatures that feed there too such as worms and shrimps This food comes in the form of plants that thrive there

Interestingly enough 200 years ago the flow of water in marsh land in the United States was controlled so that rice could be grown there Little is grown there today but 15 percent of coastal marshes are enclosed artificially in order to attract wild birds to the area and we will be examining those too

But before looking at the wildlife there are a few political issues to make you aware of There are always controversial issues when humans decide to make changes to natural habitats

During the past 20 years many objections have been voiced to the building of artificial earth walls or dikes to use the correct term on salt marshes to control the natural flow of sea water Since the walls restrict the movement of high volumes of water this means that the natural habitat of local aquatic life is reduced And because the water is shallower the temperature of the water may rise significantly during periods of low rainfall

In addition although the insects are very happy there many people are unhappy with the dikes This is not because they distract from the natural beauty of the landscape but because their presence means it is more difficult for walkers who appreciate the marshes to go where they want

There is controversy over the different values placed on the resources of the marshes Some people would like to see them used more fully for hunting while others would like to see business permits granted to allow for further development

Interestingly in the mid 20th century marshes were not thought of as valuable at all and over half of the salt marshes in the USA were destroyed at that time In the main this was due to filling the marshes to create more land for housing developments and to control the mosquito population

However state laws now do reflect the importance and growing appreciation of marshes not only as natural habitats but also because they provide a natural barrier against storm damage and therefore limit the amount of land lost to the sea

Right We will be debating some of those issues in the seminars but let us now turn our attention to the horseshoe crab which is the focus of our study this morning

Horseshoe crabs have changed very little in the last 350 million years I find them interesting in many ways because they are in fact distant relatives of the spider and not crabs at all They look quite dangerous In fact they are absolutely harmless

The horseshoe crabs main diet is one of shellfish but they will eat worms too The crab places its food near its mouth in the center of its underside where its legs are attached and grinds and crushes it there It has five pairs of legs

The female lays between 200 and 300 eggs and comes ashore to do that This process takes place in spring before the sand heats up in the summer months

Right What I am going to do now is show you some photos