Ecology is the study of the relationships among living organisms,including humans,and their physical environment. Ecology considers organisms at the individual,population,community,ecosystem,and biosphere level. Ecology overlaps with the closely related sciences of biogeography,evolutionary biology,genetics,ethology,and natural history.
Eutrophication is the "explosive growth of microorganisms,to the extent that dissolved oxygen is depleted". Other definitions emphasize the role of excessive nutrient supply:"excessive plant growth resulting from nutrient enrichment". It has also been defined as "nutrient-induced increase in phytoplankton productivity".
A wetland is a distinct ecosystem that is flooded or saturated by water,either permanently for years or decades or seasonally for a shorter periods. Flooding results in oxygen-free anoxic processes prevailing,especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or water bodies is the characteristic vegetation of aquatic plants,adapted to the unique anoxic hydric soils. Wetlands are considered among the most biologically diverse of all ecosystems,serving as home to a wide range of plant and animal species. Methods for assessing wetland functions,wetland ecological health,and general wetland condition have been developed for many regions of the world. These methods have contributed to wetland conservation partly by raising public awareness of the functions some wetlands provide. Constructed wetlands are designed and built to treat municipal and industrial wastewater as well as to divert stormwater runoff. Constructed wetlands may also play a role in water-sensitive urban design.
Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes,ponds,rivers,streams,springs,bogs,and wetlands. They can be contrasted with marine ecosystems,which have a larger salt content. Freshwater habitats can be classified by different factors,including temperature,light penetration,nutrients,and vegetation. There are three basic types of freshwater ecosystems:Lentic,lotic and wetlands. Freshwater ecosystems contain 41% of the world's known fish species.
Ecological engineering uses ecology and engineering to predict,design,construct or restore,and manage ecosystems that integrate "human society with its natural environment for the benefit of both".
Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded,damaged,or destroyed. It is distinct from conservation and preservation in that it is an "attempt to co-design nature with nonhuman collaborators." Ecological restoration can reverse biodiversity loss,combat climate change,and support local economies. The United Nations named 2021-2030 the Decade on Ecosystem Restoration.
An aquatic ecosystem is an ecosystem found in and around a body of water,in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic;lotic;and wetlands.
Functional ecology is a branch of ecology that focuses on the roles,or functions,that species play in the community or ecosystem in which they occur. In this approach,physiological,anatomical,and life history characteristics of the species are emphasized. The term "function" is used to emphasize certain physiological processes rather than discrete properties,describe an organism's role in a trophic system,or illustrate the effects of natural selective processes on an organism. This sub-discipline of ecology represents the crossroads between ecological patterns and the processes and mechanisms that underlie them. It focuses on traits represented in large number of species and can be measured in two ways –the first being screening,which involves measuring a trait across a number of species,and the second being empiricism,which provides quantitative relationships for the traits measured in screening. Functional ecology often emphasizes an integrative approach,using organism traits and activities to understand community dynamics and ecosystem processes,particularly in response to the rapid global changes occurring in earth's environment.
River ecosystems are flowing waters that drain the landscape,and include the biotic (living) interactions amongst plants,animals and micro-organisms,as well as abiotic (nonliving) physical and chemical interactions of its many parts. River ecosystems are part of larger watershed networks or catchments,where smaller headwater streams drain into mid-size streams,which progressively drain into larger river networks. The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen,which supports greater biodiversity than the slow-moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers.
A wet meadow is a type of wetland with soils that are saturated for part or all of the growing season which prevents the growth of trees and brush. Debate exists whether a wet meadow is a type of marsh or a completely separate type of wetland. Wet prairies and wet savannas are hydrologically similar.
A pond is a small,still,land-based body of water formed by pooling inside a depression,either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two,although defining a pond to be less than 5 hectares in area,less than 5 metres (16 ft) in depth and with less than 30% with emergent vegetation helps in distinguishing the ecology of ponds from those of lakes and wetlands. Ponds can be created by a wide variety of natural processes,or they can simply be isolated depressions filled by runoff,groundwater,or precipitation,or all three of these. They can be further divided into four zones:vegetation zone,open water,bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year;many ponds are produced by spring flooding from rivers. Ponds may be freshwater or brackish in nature. 'Ponds' consisting of saltwater,with a direct connection to the sea to maintain full salinity,are normally regarded as part of the marine environment. These bodies of water do not support fresh or brackish water-based organisms,and are not considered to be ponds.
Brackish marshes develop from salt marshes where a significant freshwater influx dilutes the seawater to brackish levels of salinity. This commonly happens upstream from salt marshes by estuaries of coastal rivers or near the mouths of coastal rivers with heavy freshwater discharges in the conditions of low tidal ranges.
William Mitsch,born March 29,1947,in Wheeling,West Virginia,US,is an ecosystem ecologist and ecological engineer who was co-laureate of the 2004 Stockholm Water Prize in August 2004 as a result of a career in wetland ecology and restoration,ecological engineering,and ecological modelling.
In ecology,the theory of alternative stable states predicts that ecosystems can exist under multiple "states". These alternative states are non-transitory and therefore considered stable over ecologically-relevant timescales. Ecosystems may transition from one stable state to another,in what is known as a state shift,when perturbed. Due to ecological feedbacks,ecosystems display resistance to state shifts and therefore tend to remain in one state unless perturbations are large enough. Multiple states may persist under equal environmental conditions,a phenomenon known as hysteresis. Alternative stable state theory suggests that discrete states are separated by ecological thresholds,in contrast to ecosystems which change smoothly and continuously along an environmental gradient.
In ecology,the term productivity refers to the rate of generation of biomass in an ecosystem,usually expressed in units of mass per volume per unit of time,such as grams per square metre per day. The unit of mass can relate to dry matter or to the mass of generated carbon. The productivity of autotrophs,such as plants,is called primary productivity,while the productivity of heterotrophs,such as animals,is called secondary productivity.
Ecosystem health is a metaphor used to describe the condition of an ecosystem. Ecosystem condition can vary as a result of fire,flooding,drought,extinctions,invasive species,climate change,mining,fishing,farming or logging,chemical spills,and a host of other reasons. There is no universally accepted benchmark for a healthy ecosystem,rather the apparent health status of an ecosystem can vary depending upon which health metrics are employed in judging it and which societal aspirations are driving the assessment. Advocates of the health metaphor argue for its simplicity as a communication tool. "Policy-makers and the public need simple,understandable concepts like health." Some critics worry that ecosystem health,a "value-laden construct",can be "passed off as science to unsuspecting policy makers and the public." However,this term is often used in portraying the state of ecosystems worldwide and in conservation and management. For example,scientific journals and the UN often use the terms planetary and ecosystem health,such as the recent journal The Lancet Planetary Health.
Margaret A. Palmer is a Distinguished University Professor in the Department of Entomology at the University of Maryland and director of the National Socio-Environmental Synthesis Center (SESYNC). Palmer works on the restoration of streams and rivers,and is co-author of the book Foundations of Restoration Ecology. Palmer has been an invited speaker in numerous and diverse settings including regional and international forums,science-diplomacy venues,and popular outlets such as The Colbert Report.
Erika S. Zavaleta is an American professor of ecology and evolutionary biology at the University of California,Santa Cruz. Zavaleta is recognized for her research focusing on topics including plant community ecology,conservation practices for terrestrial ecosystems,and impacts of community dynamics on ecosystem functions.
Shahid Naeem is an ecologist and conservation biologist and is a Lenfest Distinguished professor and chair in the Department of Ecology,Evolution,and Environmental Biology at Columbia University. Naeem is the author of Biodiversity,Ecosystem Functioning,and Human Well-Being,and has published over 100 scientific articles.
Ecohydraulics is an interdisciplinary science studying the hydrodynamic factors that affect the survival and reproduction of aquatic organisms and the activities of aquatic organisms that affect hydraulics and water quality. Considerations include habitat maintenance or development,habitat-flow interactions,and organism responses. Ecohydraulics assesses the magnitude and timing of flows necessary to maintain a river ecosystem and provides tools to characterize the relation between flow discharge,flow field,and the availability of habitat within a river ecosystem. Based on this relation and insights into the hydraulic conditions optimal for different species or communities,ecohydraulics-modeling predicts how hydraulic conditions in a river change,under different development scenarios,the aquatic habitat of species or ecological communities. Similar considerations also apply to coastal,lake,and marine eco-systems.
