While aquatic plants are the base or a lake’s food chain, uncontrolled rooted aquatic vegetation (macrophytes) and macro-algaes create numerous sportfish management problems. These plants tend to cover large areas of most ponds because of the abundance of relatively shallow water, usually in water less than 8 feet in depth. Few aquatic animals directly consume macrophytes or macro-algaes and so these plants tie up valuable nutrients and retard the flow of energy through the food chain to perch, largemouth bass, and catfish.
Often the high densities of these plants allow prey to hide effectively and lead to stunted fish populations. Other common problems created by macrophytes include: limiting access to the water, increased evaporation rates through transpiration, creation of environments for disease bearing insects (mosquitoes) and parasites, and degraded water quality. As you can see, a part of any lake management program must incorporate aquatic plant management.
Aquatic plants are usually grouped into four categories that include algae, true floating plants, submerged plants, and emergent plants. Algae are very primitive plants that have no true roots, stems, or leaves and do not produce flowers or seeds. Microscopic algae are important in the aquatic food chain and can be promoted through fertilization. Filamentous and macro-algaes (such as the plant chara) often cover large areas and need to be controlled to improve access and reduce oxygen epletions.
True floating plants, such as duckweed, salvinia, and water hyacinth increase evaporative water loss and can cause oxygen depletions and fish kills if they cover the entire pond surface. Submerged plants, such as bushy pondweed, coontail, and milfoil, are extremely dense which allow prey species to hide and escape from predator species. The enormous biomass produced by submerged species often cause oxygen epletions and fish kills. Emergent or shoreline plants, such as cattails, lotus, and primrose reduce access, increase evaporative water loss, and often give prey species numerous places to hide.