South Dakotans learn about hypoxia, land losses on Louisiana trip

2 August 2013

This is a combination of a guest blog from Roslyn farmer and South Dakota Corn Grower member Ryan Wagner following a recent trip to the southern tip of Louisiana 

Hypoxia by definition is an absence or lack of oxygen, and the Gulf of Mexico hypoxic zone is described as an area that does not have adequate oxygen to support marine life. Data shows that commercial fertilizer from fields, lawns and golf courses is a major source of the hypoxia. This issue has been fairly well publicized in recent years, and I think most farmers are well aware of the problem. Every year a team of researchers goes out on one of the research vessels to take readings to determine the size of the hypoxic area, and this year’s trip will start in the coming week. Scientists predict the hypoxic zone to be record large this year due in part to the big rains experienced in the Mississippi River watershed this spring.

Last year the hypoxic area was considerably smaller than in years past due to the drought and the size has varied over the years, but has clearly increased in size since research began back in 1985. Most of the world’s major rivers have hypoxia to some extent and there is a very small amount of hypoxia that occurs naturally; however, the Mississippi River’s hypoxic area is considered to be one of the world’s largest. More is known about hypoxia in the Mississippi River because it is the world’s most studied river system.

Land loss in the delta

Another major issue facing the delta that farmers may not know as much about is land loss. A river delta is an ever changing landscape that exists entirely because sediment flows down the river and deposits at the mouth. Vegetation catches the sediment and builds new land in the process. Since the 1930s, Louisiana has lost 1880 square miles of land and is predicted to lose another 1,750 square miles in the next 50 years due to man-made changes to the Mississippi River such as channelization and damming that have caused it to deliver less sediment, resulting in subsidence, or sinking of the delta land.

This is important because: 1) the land these fishing villages are built on is only inches above sea level and 2) the freshwater marshes of the delta require consistent sediment delivery to keep the saltwater from encroaching and killing off its native species. Cocodrie is considered the fastest sinking place on earth because of subsidence, and locals there have seen drastic changes in their lifetimes due to this issue. The group took a seaplane ride over the area to see some of the changes that were described to us, flying over the mouth of the Atchafalaya River, the only area of the Delta that is not losing land. The lower end of the Mississippi has changed course many times in its history, and the Atchafalaya was once the main channel of the Mississippi and currently diverts about 30% of the flow from the Mississippi.

We also had the opportunity to fish during our time in Louisiana, and our guides put us on some very nice