Florida drought affecting area fish and wildlife

The U.S. Drought Monitor has the entire area rated from "moderate drought" to "extreme" in South Florida. Water restrictions are in place for many parts of the state. In South Florida, a very dry 2006 (third driest on record for the state as a whole) and a dry beginning to 2007 had Lake Okeechobee at a record low of 8.89 feet on May 31. It should be at 13.23 feet.

It's not just the state's human residents who are affected. The fish and wildlife are feeling the effects of low water levels also.

According to Florida Fish and Wildlife Conservation Commission (FWC) officials, there are both positive and negative effects for the state's wildlife during this time.

The cycle of floods and droughts that Florida experiences is natural, normal and recurring. Florida's ecosystems are dependent on this cycle to maintain healthy fish and wildlife populations. The long-term benefits of droughts and floods often exceed the short-term negative effects.

"Short-term droughts probably are more beneficial to freshwater fish and their habitat than they are harmful," said Fred Cross, regional freshwater fisheries biologist in the FWC's regional office in Panama City.

The drought exposes lake bottoms and dries up the muck that has accumulated. Desirable vegetation expands into deepwater portions of lakes and rivers, and seeds germinate on exposed lake bottoms. However, during a drought, invasive and exotic plants such as hydrilla can become more of a problem. It also provides the opportunity to use prescribed burning to reduce vegetation in the wetlands. This creates open water habitat, which helps water quality and reduces the potential for wildfires, according to Cross.

"Droughts can increase the effectiveness of planned habitat enhancement projects," said Dale Jones, section leader for the FWC's Division of Freshwater Fisheries Management.

While water levels are low, boat ramps, docks, seawalls and other structures can be repaired. Marine species are able to go much farther upstream in some river systems, providing additional fishing opportunities to freshwater anglers.

Droughts can reduce the aquifer level, allowing sink holes to form and drain lakes. Salinity increases in tidal creeks may stress fish, and low water levels can trap fish, resulting in fish kills from low dissolved oxygen, according to biologists.

During these times of low water levels, boaters need to exercise extreme caution to prevent striking an underwater object or the bottom. At the same time, no matter how shallow the water, there always is a drowning hazard. FWC officials strongly encourage boaters always to wear their life jackets while on the water.

There also may be access problems due to boat ramps being out of water and steep dropoffs at power-loading holes at end of boat ramps that are usable at current water levels.

According to Allan Woodward, research administrator at the FWC's Gainesville Wildlife Research Lab, "Droughts can be stressful on most aquatic wildlife, including alligators."

As water levels drop, alligators fare reasonably well because of the temporary concentration of prey items (fish, turtles and birds) into remaining water, although there may be increased cannibalism.

"Under prolonged droughts, such as the one we are now experiencing, alligators may be forced to move in search of water. Traveling over dry land can cause increased mortality from motor vehicles as well as dehydration. Smaller alligators may fall prey to predators during these searches for water," Woodward said.

Movements across land usually will result in more frequent interactions with humans, and alligators may get trapped in areas from which they cannot readily escape. This results in an increase in nuisance alligator complaints.

"We have found that there is no increase in the number of attacks on humans during droughts. When moving over dry land, alligators are awkward and out of their element. They merely want to find water, which provides them with security and food," Woodward said.

Native reptiles and amphibians are adapted to periodic droughts and occasional wildfires. Droughts and fires can cause elevated mortality of reptiles and amphibians, but most populations recover quickly when rainfall returns to normal levels.

"In fact, some reptiles and amphibians depend on fires to maintain their desired habitats," Woodward said. "Snakes normally are not as much of a problem during droughts as during rapid water level increases after droughts."

For marine species, there is good and bad news during a drought.

For oysters, the increased salinity in bays and estuaries means an increased risk of parasite infection, according to Bill Arnold, research scientist at the FWC's Fish and Wildlife Research Institute in St. Petersburg.

"Clams are a high-salinity species, so drought conditions generally are good for these bivalves. However, the increased salinity also may support an increased abundance of predators," Arnold said.

Since most of the successful populations of bay scallops occur offshore, they aren't as strongly influenced by freshwater inputs. Florida droughts usually occur in spring, and the scallops spawn in fall or winter.

"By the time the drought sets in and has an influence, the scallops are relatively large and more tolerant. Scallops also are a high-salinity species, so it is the wet rather than the dry years that appear to be more problematic," Arnold said.

For the upland species, there are also pros and cons to the drought. According to Scott Johns, district biologist from the FWC's Olustee Field Office, hunters may observe smaller and fewer yearling deer this fall as the drought in North Florida occurred during the time when the fawns are born.

"This made life more difficult on these fawns and their mothers that need extra water in their diets while nursing," Johns said.

The tips and shoots of growing plants is a large part of deer diets during the spring and summer.

"This is a favorite deer food, and without the protein from these plants, fawn growth will be delayed and even antler development in bucks could be stunted this year," Johns said. "Plant production is very limited during droughts, especially those favored by wildlife such as blackberry, palmetto berry, mushrooms and low bush blueberries. Plants shut down new growth during periods of drought and conserve any water available for survival."

New growth is put off until favorable conditions return. Oaks produce fewer acorns or may not produce acorns at all during periods of drought.

Birds are generally unaffected by local drought as they can move easily to find water. However, since this drought has occurred during nesting time, many nests could have been abandoned, and are at a greater risk of predation. Bird nests are especially at risk during droughts mainly due to the increased risk of wildfire. This would impact birds that nest on the ground, such as turkey and quail, the most, according to Johns.

Research has shown bobwhite quail reproduction to be negatively affected by hot, dry periods. Although the drought in North Florida has been very dry, it was relatively cool, so quail reproduction may have not been severely impacted.

"Catastrophic events are also more likely during drought years. Large-scale, fast moving wildfires can kill and displace many species, especially those that are unable to move quickly. Because birds are very sensitive to air quality, they can be killed by smoke inhalation, even when they are many miles from the fire," he said.

However, even fires can produce benefits. Wildfires, which occur more frequently during drought periods, can open up dense, tangled areas that have become overgrown and useless to many species.

"For example, when wildfires burn the muck and peat from dry cypress ponds and wetlands, this creates openings and deepwater areas used by ducks, wading birds, and other wetland species," Johns said.

Gopher tortoises are somewhat adapted to life in a dry environment. These animals are able to conserve water in several ways.

"But the prolonged drought we have seen in North Florida this spring could have significant impacts on the hatchlings and juvenile tortoises," Johns said.

Survival during a drought is easier on larger animals than smaller ones. For example, white-tailed deer and bears are able to cover large amounts of territory in search of water.

"And as cruel as it may sound, the drought is one of nature's ways of eliminating the weaker, less vigorous individuals of a species. Nature is continually eliminating such animals from the population. The spread of disease and parasites can decrease when these animals are gone," Johns said.