Glossary of Lake Related Terms

Algae – tiny plants that live in the water as individuals, in long strands, or in clumps – these organisms make the water appear cloudy and affect how deep you can see into the water. Measured by measuring the amount of chlorophyll in water samples, more chlorophyll = more algae.

Algae bloom – when there are more algae than ‘normal’ for a particular water body

Aquatic macrophytes – plants growing in or near water that are large enough to be seen with the naked eye

Bathymetric map - a 'depth map' of the lake, contour lines drawn in the lake showing how deep the water is at different points in the lake.

Benthos – animals other than plankton growing on the bottom of the lake

Chlorophyll – a green pigment plants use to photosynthesize carbon dioxide gas into carbon contained in plant biomass

Color – the color of lake water, as when looked at through a clear glass. Color can be given a number through laboratory analysis that measures the amount of color in Platinum-Cobalt Units (PCU). High amounts of color can decrease productivity by reducing light penetration to lower depths. ‘Ridge’ type lakes in Highlands county will be nearly colorless while ‘transition’ type lakes can be naturally stained a tea color.

Depressional lakes - where there was a depression in the sea floor and where water can now accumulate

Detritus – decomposing organic matter

Emergent – plants with shoots above water and rooted in the lake bottom, in water 1-2’ deep

Epilimnion – top region in the lake, water is generally less dense, warmer and more turbulent than in the hypolimnion

Eutrophic – water bodies with high levels of nutrients, particularly N and P, and therefore with high productivity. These lakes will have large plant populations and high levels of algae.

Evapotranspiration – water lost from a lake surface through a combination of evaporation and through releases from plant leaves as plants carry out internal processes

Floating leaved – plants rooted in sediment 2-9 feet below the surface with floating or aerial leaves

Freely floating – plants growing above water and not rooted in sediments

Hypereutrophic – lakes with VERY high levels of nutrients and a lot of plant and algal growth. Fish populations are probably low due to oxygen depletion from decomposing plants and algae.

Hypolimnion – region at the bottom of the lake, water is generally denser, cooler and calmer

Limiting nutrient – usually either nitrogen or phosphorus. This is the nutrient that prevents additional plant growth because the water will ‘run out’ of this nutrient first. P is the limiting nutrient when plant growth stops because there is no more P in the water, though there is still plenty of nitrogen to support further plant growth.

Littoral zone – generally shallower areas where plants are growing in the lake bottom

Mesotrophic – lake has a moderate level of nutrients to support a moderate level of plant and algal growth, without excessive growth. These generally make fairly good fishing lakes and are also generally clear enough to be good for swimming.

Metalimnion – region intermediate to bottom and top regions in the lake, transitional heat region

Oligotrophic – lakes very low in nutrients, where there is very little plant or algal growth. Fish populations are generally low in these lakes since fish will have little algae to eat and few plants for habitat.

Pelagial zone – open water, low productivity

Periphyton – bacteria and algae growing on rocks, plants, sand, etc.

Plankton – free floating plant (phytoplankton) and animal (zooplankton) organisms

Pleuston – organisms adapted for growing at the surface of the lake

Production – growth of living organisms

Productivity – rate of growth of plants and other organisms

Profundal zone – sediments directly underneath the littoral zone where there is no plant growth

Ridge lakes – generally sinkhole lakes, formed with white sandy bottoms and relatively little organic matter in lake sediment and surrounding soils – these lakes are generally 20+ feet deep and water is very clear. Found on the ridge – close to US 27.

Secchi disc – a disc lowered into the water until it disappears – used as a standardized way to determine water clarity.

Seepage lakes - water flows into the lake from all around and/or below, but not in an isolated place as in spring-fed lakes. The lake is in the groundwater table.

Sinkhole lakes - forms when ground surface collapses to a depth sufficient to expose groundwater, a type of solution lake

Solution lakes - water wears away bedrock to form a depression

Springs - where water comes to the earth's surface in an isolated spot (may be underwater and supplying a lake or stream)

Submersed – plants growing underwater at all depths

Transition lakes – generally depressional type lakes formed on the slopes of the Lake Wales Ridge, usually less than 10 feet deep and surrounded by mucky soils, these lakes will have tea-colored water due to staining from decomposing organic matter and tannic acids.

Water clarity – the depth to which a standardized ‘secchi’ disc can be seen.

Watershed – all of the land (and water) surface surrounding a particular water body from which water flows to that water body - rainfall lands on the ground and the flows downhill to the lake.