Not associated with or derived from living organisms. Abiotic factors in an environment include such items as sunlight, temperature, wind patterns, and precipitation.

Migrating between lakes and rivers or streams.

Algae are simple plants that can range from the microscopic (microalgae), to large plants (macroalgae). Microalgae include both cyanobacteria, (similar to bacteria, and formerly called “blue-green algae”) as well as green, brown and red algae.

Anthropogenic is an adjective that describes changes in nature made by people.

Benthic Zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers.

Bioaccumulation is the accumulation of substances, such as pesticides, or other chemicals in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost by catabolism and excretion.

Associated with or derived from living organisms. The biotic factors in an environment include the organisms themselves as well as such items as predation, competition for food resources, and symbiotic relationships.

Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain.

Brown or tea-colored lake water that is acidic due to organic matter input. Nutrient levels can vary but low dissolved oxygen levels affect aquatic life.

A lake with high nutrient levels and highly productive in aquatic animal and plant life. Eutrophic literally means true nutrients or truly nutrient rich (Phosphorus and Nitrogen).

From or found in a river.

The process of mating organisms—animals or plant—of different breeds, varieties, species or genera to create a hybrid.

A lake that is extremely rich in nutrients and minerals.

Littoral zone
The part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged.

A lake with moderate nutrients levels and moderately productive in aquatic animal and plant life.

A component in foods that an organism uses to survive and grow. Macronutrients provide the bulk energy an organism’s metabolic system needs to function while micronutrients provide the necessary cofactors for metabolism to be carried out. Both types of nutrients can be acquired from the environment.

Lakes that are deep and clear with low nutrients levels, little organic matter, and a high dissolved-oxygen level.

Pelagic Zone
Any water in a sea or lake that is neither close to the bottom nor near the shore can be said to be in the pelagic zone.

The process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.

Photosynthesizing microscopic plant-like organisms at the base of the aquatic food web that inhabit the upper sunlit layer of almost all fresh waterbodies on Earth.

Microscopic organisms that drift or swim weakly in a body of water, including bacteria, diatoms, and various larvae. Plankton is an important food source for fish and other larger organisms. (See phytoplankton and zooplankton)

Polychlorinated Biphenyls (PCBs)
An organic chlorine compound with the formula C12H10−xClx. Polychlorinated biphenyls were once widely deployed as dielectric and coolant fluids in electrical apparatus, carbonless copy paper and in heat transfer fluids.

In an ecosystem, predation is a biological interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked).

Profundal Zone
The profundal zone is a deep zone of an inland body of freestanding water, such as a lake or pond, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly.

Secchi Disk
The Secchi disk, as created in 1865 by Angelo Secchi, is a plain white, circular disk 30 cm (12 in.) in diameter used to measure water transparency in bodies of water.

Having to do with “where” things are and why they occur there.

Trophic State
A method of classifying lakes. Trophic means nutrition or growth. Although lakes are arranged into a few trophic classes, each lake has a unique set of attributes that contribute to its trophic status. The three main factors that regulate the trophic state of a lake are rate of nutrient supply, climate, and shape of the lake basin.

A watershed is the area of land where all of the water that falls in it and drains off of it goes to a common outlet. Watersheds can be as small as a footprint or large enough to encompass all the land that drains water into rivers that drain into Chesapeake Bay, where it enters the Atlantic Ocean.

Zooplankton is a range of small and large animal-like organisms drifting in fresh waterbodies. Individual zooplankton are usually microscopic, but some are larger and visible with the naked eye.