Thursday, October 21, 2021

Marco’s Magnificent Estuaries

A green heron hides among the mangroves to surprise an unsuspecting fish.

A green heron hides among the mangroves to surprise an unsuspecting fish.

STEPPING STONES
Bob McConville
Master Naturalist

Ah, the beauty of those small islands surrounding Marco! Everyone wants to visit them, to see what hides among the roots and branches. Whether you get out by boat, kayak, an ecotour or paddleboard, they are a treasure to behold.

The wide array of animals and plants in this area requires some very special adaptations from nature. The Gulf of Mexico lines our western border while fresh water flows from the inland regions to form a very magical combination. This is called an “estuary.”

There are quite a few bays and lagoons in our area that are integral to the formation of estuaries. Fresh water mixes with the salty gulf to create a place of wonderful changes. The ebb and flow of tides and a differential of temperatures create a dynamic system for plants and animals alike.

Tides, temperatures, sunlight, and the water’s salinity (salt content) have created an ecosystem here to which many organisms have naturally adapted. Life here has learned to live with a range of changes, but it needs that balanced flow of both salt and fresh waters to thrive.

Many of the area shellfish, crustaceans and recreational fish spend time in estuaries, usually when they are young. In fact, it is estimated that 90% of them do so. Although many fish and crabs migrate offshore to spawn, the eggs develop into larvae that are carried back to the estuary, both currents and tides. The base of the mangrove islands, the seagrasses, salt marshes, and shallow waters in general are great hiding places from predators for smaller marine life forms. Some species grow in these areas for a short while and then move on, while others may stay for their entire lives.

Some of our area shrimp

A great egret catches a meal in an area estuary. PHOTOS BY BOB MCCONVILLE

A great egret catches a meal in an area estuary. PHOTOS BY BOB MCCONVILLE

will spawn offshore. The larvae will move toward the inland waters and, by the time they are developed into small shrimp, they will find algae and seagrasses in the estuary to conceal them from predators. Here they will find the food that they need, and when fully mature the cycle will begin again.

Other marine life uses the estuary as well. A female sawfish will journey to estuarine waters during birthing season. The young pups will thrive and grow until they are mature enough to move to deeper waters.

Bull sharks will do the same. Some adult females have been seen as far inland as Henderson Creek (not far from Collier Boulevard & Tamiami Trail) during breeding and birthing season. They are known to travel up our rivers and can give live birth to a dozen pups.

Birdlife abounds here as well. Just take a walk to the lagoon at Tigertail Beach and you can usually find a variety of herons, egrets, and other flying friends taking advantage of the smaller fish along the shoreline and at the base of the red mangrove trees.

As you kayak, boat or paddle along our amazing waterways it may difficult to see what happens below the water level. There is a whole different world down there and our ever-changing estuaries are the starting gate for much of our marine plants and animals.

BIO: Bob is a naturalist for a dolphin survey team onboard the Dolphin Explorer. He is a member of Florida SEE (Society for Ethical Ecotourism). Bob loves his wife very much!

 

Bob is the owner of Stepping Stone Ecotours and also a naturalist on board the Dolphin Explorer survey program. He is a member of Florida SEE (Society for Ethical Ecotourism). Bob loves his wife very much!

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