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Ocean floor impacts: Natural and otherwise

When we think of the impacts that man has on the oceans we automatically think of over fishing and pollution. Nature has its own impacts on aquatic systems that we think will be around forever. Take Little Lagoon as an example. It sits there a mostly placid, nearly enclosed body of water, and we think it will always remain that way. Coastal lagoons are by no means permanent and barring any major geological event will change over time. The pass into Little Lagoon has to be kept open by human intervention or otherwise it would remain closed to the Gulf unless opened by a hurricane. As time goes by Little Lagoon will fill in with sediment, become marshland and eventually dry land. This process is no doubt being helped along by man’s housing and agricultural development that adds more sediment to the system.There are other human activities going on that are not so visible or measurable that can cause problems in coastal areas. Since the end of WWII shrimp trawling has been a coastal commercial and recreational activity that has brought in billions of dollars into the Gulf Coast economy. Bottom fishing by various trawling gears for oysters, clams, scallops and fish are taking place in coastal areas of the US and almost all other countries with a coastline. These activities while seemingly benign can have major impacts on benthic aquatic ecosystems.Bottom trawlers and scallop dredges on the east coast utilize heavy gears that literally scrape the bottom to come up with seafood products. This activity destroys or severely damages the sheltering structures for many marine organisms and has a severe short or long term impact on the system. Benthic diversity is greatly reduced by these actions and results in a system that is less resilient to change.Recent regional controversy has surrounded the use of otter trawls for shrimp in areas that support coral formations. Once damaged coral can take decades and in some cases centuries to grow back, if at all. Shallow areas like Tampa and Mobile Bay and closed areas such as Little Lagoon are just as affected by shrimping.Trawling in these shallow areas stirs up large amounts of sediment that re-suspends man made pollutants and contaminants such as; fertilizer from our lawns and gardens, pesticides and insecticides from local farms and oil and gasoline runoff from roads. In small nearly closed systems like Little Lagoon, the impact from the fish by-catch can be significant. Studies, while not specific to Little Lagoon, have shown that there is ten pounds of by-catch for every pound for shrimp taken. The vast majority of these fish are juveniles that have never had a chance to breed or be available as prey to the next step up the food chain.People always seem want to point the finger of blame at someone or something because of a problem. This problem is like an old joke, which goes something like this:  A man walks into his doctor’s office and says, “Doctor, it hurts when I lift my arm like this.” The doctor says, “Don’t lift it like that anymore.” We do not have to stop shrimping we just have to figure out where, when and how to do it without damaging our marine ecosystem systems.

Think Global – Act Local!


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