Glossary of Key Terms
Glossary of Key Terms
| Term | Definition |
| Allochthonous material | Material brought into an ecosystem from the outside, such as organic solutes and debris. |
| Biomass | The organic material physically present in a given area or volume, which constitutes the standing crop. |
| Biomass yield | The addition of biomass per unit of time, representing a measure of productivity. |
| Chemosynthesis | A form of primary production where particulate and dissolved organic matter arise in the aquatic environment through chemical processes rather than photosynthesis. |
| Chlorophyll a | A plant pigment whose measurement is a type of standing crop measurement, which can be done via remote sensing from aircraft or satellites. |
| Dystrophic | The final stage in the idealized succession of lakes, characterized as a bog stage where the lake is nearly filled in by weeds and productivity has greatly decreased. Cedar Lake is given as an example. |
| Eutrophic | A state of high productivity in a body of water. Clear Lake is presented as an example of an extremely eutrophic lake. |
| Eutrophication | The process of increasing productivity in a body of water. Cultural eutrophication is accelerated by human activity such as sewage disposal and construction. |
| Information | In the context of information theory applied to ecosystems, this refers to the energy expended by a phytoplankton community for the maintenance of its community structure. |
| Light and dark bottle method | A method for estimating gross and net productivity by enclosing identical plankton samples in a transparent “light bottle” and an opaque “dark bottle” and measuring the change in oxygen content after a period of incubation. |
| Mesotrophic | A state of medium productivity in a body of water, positioned between oligotrophic and eutrophic states. Castle Lake is classified as mesotrophic. |
| Oligotrophic | A state of low productivity in a body of water. Lake Tahoe is an example. |
| Periphyton | Attached algae, for which the standing crop measurement method is still used. |
| Photosynthesis | The process by which plants convert inorganic matter into organic matter, forming the basis of primary production. |
| Phytoplankton | Microscopic floating plants that are a key component of primary producers in aquatic ecosystems. |
| Plankton | Microscopic floating plants and animals that can be collected in a net to measure standing crop. |
| Primary producers | Organisms that convert inorganic matter into organic matter, forming the base of the food web. In aquatic ecosystems, these include algae, bacteria, and sometimes higher plants like water grasses. |
| Primary productivity | The first level of productivity in a system, representing the rate at which organic material is created by primary producers. It can be measured as the rate of photosynthesis or the addition of biomass over time. |
| Radioactive carbon (¹⁴C) method | A highly sensitive method for measuring photosynthetic rates by inoculating water samples with radioactive carbon (Na₂¹⁴CO₃) and determining the amount of carbon fixed in particulate form after a short incubation. |
| Standing crop | The part of biological production per unit area or volume that is physically present as biomass and not lost to respiration. |
| Trophic-dynamic model | A model of an aquatic ecosystem, developed by Lindeman (1942), that introduced the concept of “energy flow” to describe the efficiency of energy transfer between trophic levels. |