Aquatic Plant Life

Overview

In addition to the detrimental growth caused by eutrophication, the overgrowth of aquatic plants in Indian Lake is a result of the introduction of invasive and non-native plants into the local ecosystem. The danger brought by invasive plants is that they will edge out and replace the native species, either by being more resilient to changes in the water or by not becoming part of the food chain. If a plant is not eaten by the local wildlife it can grow unchecked, quickly crowding out and removing the native plants as a food source [5]. This means that if the fish and invertebrates can't adapt they will starve, decimating the upper levels of the food chain. During our survey we identified three categories of aquatic plants, submerged, floating, and emergent, as documented in the following pages.

Invasive Plants

The aggressive growth of certain non-native plants poses a major threat to the health of the ecosystem around Indian lake. Invasive plant species usually grow unencumbered by predators because animals in the native ecosystem are unlikely to eat them [5]. As invasive plants subvert the native plants, they remove a large part of the food source for the fish population. This, combined with the decrease in dissolved oxygen caused by eutrophication, the survival rate for local fish decreases severely.

Growth Distributions

With a survey like this it is necessary to understand the relationship between the presence of certain plants and the depth at which they are found. Most aquatic plants only grow in one depth region of a lake. Because sunlight can only penetrate so far into water, a plants need for light limits the depth to which it can grow. The portion of a lake deep enough that the sun does not reach the bottom is known as the Limnetic zone [6]. This zone usually lacks any aquatic vegetation due to this lack of sunlight. As seen in previous surveys and confirmed during our survey, the center of Indian Lake is a Limnetic Zone. The zone most important to this survey was the Littoral zone. This zone is far enough from shore that submerged, emergent, and floating plants grow but also shallow enough that light reaches the bottom and all plants are able to receive proper nutrition.

Lake Zones

Developed as Part of a WPI Sponsored Project
In Affiliation with The Indian Lake Watershed Association
Worcester, MA 2013