AN EYE ON NATURE
By Larry Eichert

While attending a meeting the other night, people were talking about the large number of white pelicans on our lakes and retention ponds. Why are they here?

They are only the members of the cast that are putting on the play. The real story began with the writing of the play itself. It all started last year with El Nino in the Pacific Ocean which caused a change in the weather patterns that allowed the prevailing arctic winter winds to dip down through the north American continent bringing the arctic clippers down to the gulf of Mexico giving us such a cold winter in Florida.  This ultimately had an effect on the local fish and plant population setting off a chain of reactions that caused a temporary shift in the cyclic active in the ecosystems of our natural environment.

To understand what is happening we must enter the world of bacteria and fungi that decompose dead organisms recycling their nutrients back into the environment. Remember the green pond scum (various algae) that covered our wetlands last summer and the dead plants that can be found within the water and around the banks, they provide the food source that starts this cyclic reaction. Now that the temperatures are rising with the coming of spring these are being decomposed by the bacteria.

The warm temperature and the available dead organic matter allow the bacteria to proliferate, increasing the decomposition rate. This places a variety of available nutrients into the water changing the pH of the water. One of the most common compounds formed is tannic acid.  At the same time the temperature of the water is increasing making the fish population more active increasing their metabolism and respiration. Then add some rain to stir up the water increasing its dissolved oxygen content and this makes both the bacteria and fish become even more active. This in turn sets off a chain reaction in enzyme activity in all living organisms. Enzymes can only function at specific temperatures and pH ranges. Putting this all together you produce a shift in the available nutrient supply which becomes the food for various organisms.

All of this has a profound effect on the fish population. The change in pH stimulates the fish to breed and lay eggs. You can see their nests along the shore line below the water level. They look like hollowed out baskets in the sand.  At the same time the bacteria population is exploding. With the increase in temperature of the water the eggs from last year’s zoo plankton begin to hatch and the photo plankton begin to reproduce.

The zoo plankton population begins to consume the bacteria and the photo plankton uses the dissolved nutrients provided by the bacteria and fungi as a food source increasing their rate of photosynthetic reproduction with the increase in the temperature of the water. This in turn begins to decrease the over production of the bacteria and fungi activity keeping the system in check. Now there is more photo and zoo plankton than the system can support. But don’t be alarmed because at the same time the fish eggs are beginning to hatch and these organisms become the food supply of the fish fry.

While all of this is going on the increase in temperature and the availability of some rain coupled with wind activity now allow the dormant seeds from last year’s plants to be blown around and settle in the soil along with the seeds that have already been deposited and they begin to germinate. The humus (dead organic matter) content of the soil and the mineral nutrients provided from the decomposition of rock and sand provide the nutrients for plants to grow. This can be seen by how fast the native vegetation takes hold in our yards, getting a head start over the grasses and plants that we feel should be planted there. These plants want to reproduce as fast as they can to take advantage of the available food supply and sun light.

The plants put all of their energy in the development of their reproductive systems producing flowers. The flowers become the landing pads for a vector (insect, bird or other animal) to fertilize their seeds (female sex cell) and scatter pollen (male sex cell). If the plant possesses a superior flower, with the stigma (male reproductive sex organ) being taller than the style (female reproductive organ) then the plant can self fertilize. If the reverse is true then the plant needs some other method to propagate its own species. These other methods include transmission by wind or vectors. The plants that are growing in the literal zones around the water’s edge are also attracting insects to the water by flowering and producing fat molecules (nectar) that attract insect vectors which also serve as a food supply for fish and small birds.

Watch the lakes and retention ponds carefully to see how various bird species form an orchestra with each one playing its part in a symbiotic relationship. The anhinga arrives first to see what food is available. Their approach is down wind like an airplane gliding into position. Sometimes they use their wings to form a shadow over the water for visibility, other times they use them to splash up the water confusing the fish but most often they look forward and dive into the water catching the fish from behind.  If one or two anhinga are being successful soon others will come to join them.

By this time the word is out in the bird community and other species come to become part of the feast. But there is a hierarchy and protocol to be followed.  The blue and white herons soon arrive and wait patiently along the banks waiting for the larger fish to pass by as they scurry away from the anhinga. At the same time the egrets (snowy & cattle) come in to catch smaller fish that come near the banks.

Occasionally you can see ibis walking the banks looking for grubs and fresh water clams and wood storks wading within the reeds. (It is late in the season for wood storks to be in this area. They should be nesting down at Corkscrew swamp. However since the water level there is so high they are unable to see their food supply and have not begun to nest yet.)

This finally brings us back to why the white pelicans are here. White pelicans would normally be closer to the coast skimming the waters filling their pouches with fish but because of the fish kill due to the cold weather this winter and the colder waters of the gulf they are coming inland where the water is warmer and the fish are more abundant.

We are often oblivious to these complex interrelationships that have taken hundreds of years to develop into an energy efficient community of living things. Some of them build up the soil - a living organism in itself, others help to provide food - a virtual organized pot luck dinner, a feast for those consuming the harvest of which they partake. Other members transport needed supplies by air and path into the community providing diversity and supplies. Still others take what is left over and recycle it back into the natural resources necessary for community development.

Each type of system is a subdivision of the overall community where every neighbor next door provides help to others allowing the community to survive and flourish. Nothing is wasted. The waste product of one organism becomes the food supply for another. A healthy, naturally functioning community (eco-system) has its own unique plants (flora), animals (fauna) and decomposers (recyclers). These systems contain a food supply, water, light and air for both adult and immature creatures to survive. There are places for roosting, nesting and hiding from the elements or predators.

Ultimately we are a part of the environment not apart from it. The better we understand it the more respect we will have for it to preserve it!

All pictures were taken in Stoneybrook 2010 by Larry Eichert