Sediment trap
Encyclopedia
Sediment traps are instruments used in oceanography
to measure the quantity of sinking particulate organic (and inorganic) material in aquatic systems
, usually ocean
s. This flux of material is the product of biological
and ecological
processes typically within the surface euphotic zone, and is of interest to scientist
s studying the role of the biological pump
in the carbon cycle
.
Sediments traps normally consist of an upward-facing funnel
that directs sinking marine snow
towards a mechanism for collection and preservation. Typically, traps operate over an extended period of time (weeks to months) and their collection mechanisms may consist of a series of sampling vessels that are cycled through to allow the trap to record the changes in sinking flux with time (for instance, across a seasonal cycle
). Preservation of collected material is necessary because of these long deployments, and prevents sample decomposition
and its consumption
by zooplankton
"swimmers".
Traps are often moored at a specific depth in the water column
(usually below the euphotic zone or mixed layer
) in a particular location, but some are so-called Lagrangian
traps that drift with the surrounding ocean current
s (though they may remain at a fixed depth). These latter traps travel with the biological systems that they study, while moored traps are subject to variability introduced by different systems (or states of systems) "passing by". However, because of their fixed location moored traps are straightforward to recover for analysis of their measurements. Lagrangian traps must surface at a pre-determined time, and report their position (usually via satellite
) in order to be recovered.
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...
to measure the quantity of sinking particulate organic (and inorganic) material in aquatic systems
Aquatic ecosystem
An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems....
, usually ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
s. This flux of material is the product of biological
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
and ecological
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
processes typically within the surface euphotic zone, and is of interest to scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s studying the role of the biological pump
Biological pump
In oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the ocean's interior.-Overview:...
in the carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
.
Sediments traps normally consist of an upward-facing funnel
Funnel
A funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel, spillage would occur....
that directs sinking marine snow
Marine snow
In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below. The term was first coined by the explorer William Beebe as he...
towards a mechanism for collection and preservation. Typically, traps operate over an extended period of time (weeks to months) and their collection mechanisms may consist of a series of sampling vessels that are cycled through to allow the trap to record the changes in sinking flux with time (for instance, across a seasonal cycle
Season
A season is a division of the year, marked by changes in weather, ecology, and hours of daylight.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
). Preservation of collected material is necessary because of these long deployments, and prevents sample decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
and its consumption
Ingestion
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking...
by zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
"swimmers".
Traps are often moored at a specific depth in the water column
Pelagic zone
Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...
(usually below the euphotic zone or mixed layer
Mixed layer
The oceanic or limnological mixed layer is a layer in which active turbulence has homogenized some range of depths. The surface mixed layer is a layer where this turbulence is generated by winds, cooling, or processes such as evaporation or sea ice formation which result in an increase in salinity...
) in a particular location, but some are so-called Lagrangian
Lagrangian
The Lagrangian, L, of a dynamical system is a function that summarizes the dynamics of the system. It is named after Joseph Louis Lagrange. The concept of a Lagrangian was originally introduced in a reformulation of classical mechanics by Irish mathematician William Rowan Hamilton known as...
traps that drift with the surrounding ocean current
Ocean current
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...
s (though they may remain at a fixed depth). These latter traps travel with the biological systems that they study, while moored traps are subject to variability introduced by different systems (or states of systems) "passing by". However, because of their fixed location moored traps are straightforward to recover for analysis of their measurements. Lagrangian traps must surface at a pre-determined time, and report their position (usually via satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
) in order to be recovered.
See also
- Biological pumpBiological pumpIn oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the ocean's interior.-Overview:...
- f-ratioF-ratioIn oceanic biogeochemistry, the f-ratio is the fraction of total primary production fuelled by nitrate . This fraction is significant because it is assumed to be directly related to the sinking flux of organic marine snow from the surface ocean by the biological pump...
- Marine snowMarine snowIn the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below. The term was first coined by the explorer William Beebe as he...
- Mooring (oceanography)Mooring (oceanography)thumb|right|Sketch of a mooring with traps and current metersA mooring in oceanography is a collection of devices, connected to a wire and temporarily anchored on the sea floor. The devices are current meters to measure the direction and speed of ocean currents, sediment traps to catch settling...
- Primary productionPrimary production400px|thumb|Global oceanic and terrestrial photoautotroph abundance, from September [[1997]] to August 2000. As an estimate of autotroph biomass, it is only a rough indicator of primary production potential, and not an actual estimate of it...