I want to focus the article I write for this week on the other lessons we learned, concerning what is affecting the ecosystems around Vester and what could be done to monitor it.
The main area of focus for Vester Marine Lab, or rather the area that is in immediate proximity to the lab, is Estero Bay. Estero Bay is a large estuary that takes up most of the coastline area of Bonita Springs, Florida, where the Vester Marine Lab is located. The habitats of Estero Bay consist of seagrass beds, algal beds, mangrove forests, mudflats, and oyster reefs. Each of these habitats work together to form a healthy estuarine ecosystem. Even in the 1960's, before the need to protect natural resources became nationally recognized, the residents of the Estero Bay area at this time refused to allow developers to drain the bay for commercial uses. They recognized that the seagrass beds were the main habitat of the juvenile fish whose adult counterparts are a major staple of the fishing industry. However, the interconnected relationship of the different habitats means that a great number of factors influenced by humans and human development affect the ecosystem of Estero Bay.
The watershed of Estero Bay (the area for which water from land drains into a body of water) consists of most of the southern portion of Lee County, and it also extends into neighboring counties. As such, its main sources of freshwater are runoff from the developed areas of Lee County, delivered either by a network of small rivers, or by culverts and storm drains.
Runoff from developed areas usually has excess levels of nutrients, which can affect the health of the ecosystems in various ways:
- Phytoplankton and algae are the first organisms to take up nutrients. Some species of these organisms produce toxic byproducts.
- Seagrasses grow better when nutrients are slowly introduced. Macroalgae (large algae, look like plants) do not directly compete with seagrasses for space, but an expansion of the surface area they cover indicates that the microalgae (microscopic) population has increased. Both microalgae and phytoplankton compete with seagrasses for light, and are more likely to absorb it since they sit at the water's surface, or on the surface of seagrass blades.
- Organisms that grow on plants without taking nutrients from the plant or eating the plant are known as epiphytes. Microalgae and other organisms acting as epiphytes on seagrass blades block most of the light that seagrass need to absorb to survive.
- Epiphytes are normally kept in check by organisms such as sea snails or sea slugs, who graze the epiphytes off of the seagrass blades. The populations of such organisms are threatened, leading to overgrowth of epiphytes.
- Propeller scars and strikes in seagrass or oyster beds are an issue that many environmentally conscientious people are aware of. It takes approximately ten years for a propeller scar in a seagrass bed to heal over properly in the presence of healthy seagrass. This healing process takes longer if the seagrass bed is considerably weakened.
- Individual seagrasses contribute to maintaining the health of the entire seagrass bed. If many of the individual plants are removed, damaged, or sickened, the seagrass bed is more likely to severely die off.
- Watercraft stir up sediment, which reduces clarity of the water and visibility for organisms. The least dense of sediment grains could remain suspended in water for days in perfectly still conditions, but longer if the silt is stirred up again.
- Mangrove forests are used by marine birds as colonies of nests, or rookeries. We were informed that the boat should not come any closer than 300 feet of the rookery we were observing. Some birds stand on their eggs during incubation, and could crush their eggs when fleeing from what they perceive as a threat.
- Humans could startle the birds into temporarily abandoning their eggs and/or chicks. Incubation is not only warming the chicks, but regulating the offspring's body temperature, providing protection from the blazing sun.
These are some of the environmental factors that continuously affect the health of Estero Bay.
Learning about the factors that affect the health of even the smallest ecosystem are necessary for helping to protect the natural resources that affect the abundance of natural resources in our nation.