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Abundance Index -
Information obtained from samples or observations
and used as a measure of the weight or number of fish which make up a stock.
Acid rain -
Natural rainfall which contains nitric and sulfuric acids due to
oxides of nitrogen and sulfur dioxide discharged into the air by industries, power plants,
Aestivation - es·ti·va·tion
Inactivity or dormancy during drought periods.
Algae - al-jee
Simple rootless plants that grow in bodies of water (e.g. estuaries) at rates
in relative proportion to the amounts of nutrients (e.g. nitrogen and phosphorus)
available in water.
Allowance - The allowed nutrient load a source may discharge.
Amphibian - a cold-blooded vertebrate that spends some time on land but must breed and
develop into an adult in water. frogs, salamanders, and toads are amphibians.
- uh-nad-ruh-muh s
Fish that spend most of their life in salt water but migrate into freshwater tributaries
Not containing oxygen or not requiring oxygen.
A condition where no oxygen is present. Much of the "anoxic
zone" is anaerobic, with absolutely no oxygen, a condition in which toxic hydrogen
sulfide gas is emitted in the decomposition process.
Anthropogenic - an·thro·po·gen·ic
Of human origin.
The farming of plants and animals that live in water (i.e. shellfish,
Living in water.
A group of animals including: spiders, ticks, scorpions, and
mites that have four pairs of legs and whose body is divided into two segments.
A large group of invertebrate animals with jointed legs, including the
insects, scorpions, crustaceans and spiders.
Artificial reef -
A structure aggregated from material designed to attract living
aquatic organisms (i.e. oyster reef)
Any organism that is able to manufacture its own food. Most plants
are autotrophs, as are many protists and bacteria. Autotrophs may be photoautotrophic,
using light energy to manufacture food, or chemoautotrophic, using chemical energy.
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A still body of water or a still portion of a larger body
of water, unaffected by the flow of the larger body of water. An example would be a small
stagnant branch of a river.
Stream or river flows consisting entirely of groundwater
The physical characteristics, including depth, contour, and shape of
the bottom of a body of water.
The numeric level of nutrient load at a particular point in time that
serves to establish nurtient reduction goals and allowances.
Bay Scapes -
Environmentally-sound landscapes benefiting people, wildlife, and the
Chesapeake Bay. They are low-input landscapes, requiring less mowing, less fertilizing,
and less pesticide use. They help to protect the water quality in our streams, rivers, and
the Chesapeake Bay. Along with reducing pollution, BayScapes provide diverse habitats for
songbirds, small mammals, butterflies, and other creatures.
Benthic macroinvertebrates -
Macroinvertebrates are large, generally
soft-bodied organisms that lack backbones. Benthic macro-invertebrates live in or on the
bottom sediment in aquatic environments.
Benthos - A group of organisms, most often invertebrates, that live in or
on the bottom in aquatic habitats (such as clams that live in the sediments) which are
typically immotile or of limited motility or range.
Best Management Practices (BMP) -
A practice or combination of practices
that provide the most effective and practicable means of controlling point and nonpoint
pollutants at levels compatible with environmental quality goals.
Bilateral Symmetry -
A body design found in most animals in which if an
imaginary plane divided the body into left and right halves, each side would be a mirror
image of the other..
The uptake and storage of chemicals (e.g. DDTs, PCBs) from the
environment by animals and plants. Uptake can occur through feeding or direct absorption
from water or sediments.
A simple biological test that uses an indicator organism to
measure the potency of a given substance in a biological system. An example of a bioassay
would be a test that measures algal growth in response to different nutrient
Biological Nutrient Removal (BNR) -
A temperature dependent process in
which the ammonia nitrogen present in raw wastewater is converted by bacteria first to
nitrate nitrogen and then to nitrogen gas.
The quantity of living matter, expressed a concentration or
weight per unit area.
Bioretention sites, also called "Rain Gardens,"
are an innovative method for stormwater management that retains stormwater on site and
uses plants and layers of soil, sand, and mulch to reduce the amount of nutrients and
other pollutants that enter local waterways.
The flora and fauna of a region.
A population burst of phytoplankton that remains within a defined part of
the water column
A wetland that has poorly drained acidic peat-soil dominated by sedges and
Somewhat salty water, as in an estuary.
An entity that purchases nutrient credits.
Fishes or other animals caught by accident in fishing gear. Bycatch is
usually thrown back dead or dying.
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Cap - The total nutrient load that is allowed to be discharged into a given
water body. The cap is the baseline minus the amount of load reduction needed to meet the
goal. The cap is equal, or greater than, the sum of the allowances.
Cap load - Cap loads are the maximum pollutant load of nutrients and sediments that
can be allowed.
Catadromous - Fish that live in freshwater and migrate to saltwater to
spawn (i.e. American eel).
Centrarchidae - Cen·trar·chi·dae
Sunfish family, include Largemouth, spotted and
smallmouth "black bass", bluegill and both black and white crappies
The sunfish family are generally deep-bodied and compressed laterally. Their
fins often have both soft rays and stiff spines that provide protection from
predators. The caudal fin (tail) is notched or slightly forked. Paired
pectoral and pelvic fins are located towards the front of the fish. Sunfish
generally thrive in warm water, fertile lakes with abundant shoreline
aquatic plants or other protective cover within which they can easily
All sunfish are nest builders, and their saucer-shaped nests can be
frequently observed along the shoreline of ponds, lakes and streams in late
spring. These nests usually consist of a circular depression in silt, sand
or gravel that is lighter in color than the surrounding substrate because an
adult male has consistently scraped silt, algae or other organic material
from accumulating within the nest area. An active, nest-guarding male can
often be observed swimming within the nest vicinity, guarding both eggs and
A few days after hatching, the young emerge from the
nest, at which time the guarding parent leaves them to care for themselves.
All sunfish are carnivorous. Small species and young individuals of larger
species eat small invertebrates (such as insects, crustaceans, and mollusks)
and small fish. Larger individuals feed more frequently on fish and
crayfish. The maximum size of sunfish varies greatly; the longear sunfish
seldom reaches 5 inches or weighs more than a few ounces, whereas the
largemouth bass may reach 2 feet and exceed 10 pounds.
Channelisation - Artificial modification of a watercourse to ensure
maximum flow and minimise flooding.
Chlorophyll a - A pigment contained in plants that is used to turn light energy
into food. Chlorophyll also gives plants their green color.
Cilia - a tiny projecting thread, found with many others on a cell or microscopic
organism, that beats rhythmically to aid the movement of a fluid past the cell or movement
of the organism through liquid.
Class - Subdivision of a phylum containing a group of related orders.
Any of various widely distributed soft-finned fishes
of the family Clupeidae, which includes the herrings, menhadens, shad and sardines
Coastal plain - The level land with generally finer and fertile soils downstream
of the piedmont and fall line, where tidal influence is felt in the rivers.
Coelom - Body cavity or space between the body wall and the digestive
Coliform bacteria - A group of bacteria primarily found in human and animal
intestines and wastes. These bacteria are widely used as indicator organisms to show the
presence of such wastes in water and the possible presence of pathogenic
(disease-producing) bacteria. Escherichia coli (E. coli) is one of the fecal
coliform bacteria widely used for this purpose.
Commensal - Having benefit for one member of a two-species association but
neither positive nor negative effect on the other.
Congeneric - Belonging to the same genus.
Conspecific - Belonging to the same species.
Consumer - Any organism which must consume other organisms (living or
dead) to satisfy its energy needs.
Contaminant - Anything that to make something impure, unclean, or polluted,
especially by mixing harmful impurities into it or by putting it in contact with something
Copepod - A type of small planktonic crustacean. Copepods are a major group
within the mesozooplankton, and are both important grazers of phytoplankton and food for
Credits - The amount of nutrient load reduced below the allowance.
Crustaceans - The class of aquatic Arthropods including copepods, isopods,
amphipods, barnacles, shrimp, and crabs which are characterized by having jointed
appendage and gills.
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Demersal - refers to fish eggs which are neutrally or negatively
buoyant and sink to the substrate.
Denitrification - The conversion of nitrite and nitrate nitrogen (after
nitrification) to inert nitrogen gas. This treatment process requires that little or no
oxygen be present in the system and that an organic food source be provided to foster
growth of another type of bacteria. The organic food source can be either recycled waste
activated sludge or methanol. The resultant nitrogen gas is released to the atmosphere.
Designated use - An element of a water quality standard, expressed as a narrative
statement, describing an appropriate intended human and/or aquatic life objective for a
water body. Designated uses for a water body may include: recreation, shellfishing, water
supply and/or aquatic life habitat.
De-snagging - Removing logs or branches from a watercourse.
Detritus - Accumulated organic debris from dead organisms, often an important
source of nutrients in a food web.
Detrivore - Any organism which obtains most of its nutrients from the detritus in
Diadromous - Refers to fishes that migrate between fresh water and marine
environments in either direction.
Diatoms - Microscopic algae with plate like structures composed of silica.
Diatoms are considered a good food source for zooplankton.
Dinoflagellate - Algae of the order Dinoflagellata.
Dischargers The sources that emit, give off, or dispose of a gas or liquid.
Dissolved Inorganic Nitrogen (DIN) - An important nutrient for the growth of
plants. DIN is nitrogen that is readily usable by plants.
Dissolved Oxygen - Microscopic bubbles of oxygen that are mixed in the water and
occur between water molecules. Dissolved oxygen is necessary for healthy lakes, rivers,
and estuaries. Most aquatic plants and animals need oxygen to survive. Fish will drown in
water when the dissolved oxygen levels get too low. The absence of dissolved oxygen in
water is a sign of possible pollution.
Diurnal - Active during daylight.
Diversity - An ecological measure of the variety of organisms present in a
Dorsal - anatomy of or on the back: relating to or situated on the back of the
Dry Deposition - Atmospheric deposition that occurs when particles settle to a
surface, collide with and attach to a surface (adsorption) or are absorbed.
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Echinoderm - a marine invertebrate animal that has a radially symmetrical body,
tube feet, and a system of calcareous plates under the skin. Starfish, sea urchins, sea
lilies, and sea cucumbers are echinoderms.
Ecology - The study of interrelationships between living things and to their
Ecosystem - All the organisms in a particular region and the environment
in which they live. The elements of an ecosystem interact with each other in some way, and
so depend on each other either directly or indirectly.
Effluent - The discharge to a body of water from a defined source, generally
consisting of a mixture of waste and water from industrial or municipal facilities.
Emergent Wetland - A wetland dominated by nonwoody, soft-stemmed plants.
Endangered - A species that is in immediate danger of becoming extinct and needs
protection to survive.
Endemic species - A species that is restricted in its distribution to a
particular locality or region.
Environment - The place in which an organism lives, and the circumstances under
which it lives. Environment includes measures like moisture and temperature, as much as it
refers to the actual physical place where an organism is found.
Environmental data - any measurements or information that describe environmental
processes, location, or conditions; ecological or health effects and consequences; or the
performance of environmental technology. For EPA, environmental data include information
collected directly from measurements, produced from models, and compiled from other
sources such as data bases or the literature.
Environmental technology - an all-inclusive term used to describe pollution control
devices and systems, waste treatment processes and storage facilities, and site
remediation technologies and their components that may be utilized to remove pollutants or
contaminants from or prevent them from entering the environment. Examples include wet
scrubbers (air), soil washing (soil), granulated activated carbon unit (water), and
filtration (air, water). Usually, this term applies to hardware-based systems; however, it
also applies to methods or techniques used for pollution prevention, pollutant reduction,
or containment of contamination to prevent further movement of the contaminants, such as
capping, solidification or vitrification, and biological treatment.
Epifaunal - Plants, animals and bacteria that are attached to the hard bottom or
substrate (for example, to rocks or debris); are capable of movement; or that live on the
Epiphyte - A plant which grows upon another plant. The epiphyte does not
"eat" the plant on which it grows, but merely uses the plant for structural
support, or as a way to get off the ground and into the canopy environment.
Epiphytic - Substances that grow or accumulate on the leaves of submerged aquatic
plants. This material can include algae, bacteria, detritus, and sediment.
Estuarine species - A permanent resident of an estuary. Also called a resident
Estuary - A semienclosed body of water that has a free connection with the
open sea and within which seawater (from the ocean) is diluted measurably with freshwater
that is derived from land drainage (i.e. the Chesapeake Bay). Brackish estuarine waters
are decreasingly salty in the upstream direction and vice versa. The ocean tides are
projected upstream to the fall lines.
Eutrophic - Describes an aquatic system with high nutrient concentrations. These
nutrient concentrations fuel algal growth. This algae eventually dies and decomposes, with
reduces the amount of dissolved oxygen in the water.
Eutrophication - The fertilization of surface waters by nutrients that were
previously scarce. Eutrophication through nutrient and sediment inflow is a natural aging
process by which warm shallow lakes evolve to dry land. Human activities are greatly
accelerating the process. The most visible consequence is the proliferation of algae. The
increased growth of algae and aquatic weeds can degrade water quality.
Extinct species - A species which has disappeared from existence due to either
natural or human-induced means (opposite of extant).
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Fall Line - A line joining the waterfalls on several rivers that marks the point
where each river descends from the upland to the lowland and marks the limit of
navigability of each river.
Fecundity - The number of eggs produced per female per unit time (often:
per spawning season)
Filter feeder - An organism which filters food from the environment via a
straining mechanism (such as gills)(i.e. barnacle)
Food chain / food web - The network of feeding relationships in a community as a
series of links of trophic levels, such as primary producers, herbivores, and primary
carnivores. Includes all interactions of predator and prey, along with the exchange of
nutrients into and out of the soil. These interactions connect the various members of an
ecosystem, and describe how energy passes from one organism to another.
Freshet - An increase of water flow into an estuary during the late
winter or spring, owing to increased precipitation and snow melt in the watershed.
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Habitat - The place and conditions in which an organism lives.
Hermaphroditic - An organism having both sexes: a plant or animal having both
male and female reproductive organs and secondary sexual characteristics.
Histology - The study of tissue sectioned as a thin slice,
using a microtome. It can be described as microscopic anatomy. The
photographing of stained cells is called histography. Histology is an
essential tool of biology
Hydrological - The scientific study of the properties, distribution, and effects
of water on the earth's surface, in the soil and underlying rocks, and in the atmosphere.
Hypoxic - A condition where only very low levels of oxygen are present.
Insectivorous - Feeding on insects
Intertidal - The area of shore located between high and low tides.
Introduced Species - Species which have been intentionally or
brought into a region or area. Also called exotic species.
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Jetty - a wall or other barrier built out into a body of water to shelter a
harbor, protect a shoreline from erosion, and/or redirect water currents
Larva - A discrete stage in many species, beginning with zygote formation and
ending with metamorphosis.
Light attenuation - Absorption, scattering, or reflection of light by water,
chlorophyll a, dissolved substances, or particulate matter. Light attenuation reduces the
amount of light available to submerged aquatic vegetation.
Littoral zone - Area between high and low water marks on a body of
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Macro-organism - An organism visible without the aid of a microscope.
Macrophyte - An individual alga large enough to be seen easily with the unaided
Macroplankton - Planktonic organisms that are 200-2,000 micrometers in size.
Marine - Refers to the ocean.
Marsh - An emergent wetland that is usually seasonally flooded or wet, and often
dominated by one or a few plant species.
Mesohaline - Pertaining to moderately brackish water with low range
salinities (from 5-18 parts per thousand)
Mesotrophic - Describes an aquatic system somewhere between eutrophic (nutrient
enriched) and oligotrophic (nutrient poor).
Micro-organism - An organism requiring magnification to see/study (microscopic).
Micron - A unit of measure equal to one thousandth of a millimeter
Migratory - Describing groups of organisms which move from one habitat to another
on a regular or seasonal basis.
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Native Species - Species which have lived in a particular region or area for an
extended period of time.
Niche - A general term referring to the range of environmental space
occupied by a species.
Nitrification the process to which bacterial populations under aerobic
conditions, gradually oxidize ammonium to nitrate with the intermediate formation of
nitrite. Biological nitrification is a key step in nitrogen removal in wastewater
Nitrogen - (N) is used primarily by plants and animals to synthesize protein.
Nitrogen enters the ecosystem in several chemical forms and also occurs in other dissolved
or particulate forms, such as tissues of living and dead organisms.
Nutrients - Compounds of nitrogen and phosphorus dissolved in water which are
essential to both plants and animals. Too much nitrogen and phosphorus act as pollutants
and can lead to unwanted consequences - primarily algae blooms that cloud the water and
rob it of oxygen critical to most forms of aquatic life. Sewage treatment plants,
industries, vehicle exhaust, acid rain, and runoff from agricultural, residential and
urban areas are sources of nutrients entering the Bay.
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Oligohaline - Pertaining to moderately brackish water with low range salinities
(from .5-5 parts per thousand)
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Parasite - A plant or animal which lives on or in an
organism of another species from which it derives its nutrition and/or protection; usually
without benefit to the host and often with harmful effects.
pH - Measure of the acidity or basicity of water (-log10 of the activity of
hydrogen ions in water).
Phosphorus - ((P) A key nutrient in the Bay's ecosystem, phosphorus occurs in
dissolved organic and inorganic forms, often attached to particles of sediment. This
nutrient is a vital component in the process of converting sunlight into usable energy
forms for the production of food and fiber. It is also essential to cellular growth and
reproduction for organisms such as phytoplankton and bacteria. Phosphates, the inorganic
form are preferred, but organisms will use other forms of phosphorus when phosphates are
Photic zone - Layer of a body of water that recieves ample sunlight for
photosynthesis (usually less than 100m).
Photosynthsis - The process by which plants convert carbon dioxide and water into
carbohydrates and oxygen. The carbohydrates are then available for use as energy by the
plant or other consuming organisms. (CO2+ H2O +SUNLIGHT= C6H12O6
+ O2 ). This process is also referred to as "primary production."
Phytoplankton - Plankton are usually very small organisms that cannot move
independently of water currents. Phytoplankton are any plankton that are capable of making
food via photosynthesis.
Plankton - Small or microscopic algae and organisms associated with
surface water and the water column.
Polycyclic Aromatic Hydrocarbon (PAH) - a chemical compound composed of fused six
Polychlorinated Biphenyl (PCB) - a chemical compound composed of a
bi-phenyl group and chlorine atoms.
Polyhaline - Pertaining to waters with salinities of 18-30 parts per
ppt - Parts per thousand (used as a measurement of salinity).
Primary Producers - organisms, such as algae, that convert solar energy to
organic substances through the molecule, chlorophyll. Primary producers serve as a food
source for higher organisms.
Quality Assurance (QA) - an integrated system of management activities involving
planning, implementation, documentation, assessment, reporting, and quality improvement to
ensure that a process, item, or service is of the type and quality needed and expected by
Quality Assurance Project Plan - a document describing in comprehensive detail the
necessary quality assurance, quality control, and other technical activities that must be
implemented to ensure that the results of the work performed will satisfy the stated
Quality Control (QC) - the overall system of technical activities that measures the
attributes and performance of a process, item, or service against defined standards to
verify that they meet the stated requirements established by the customer; operational
techniques and activities that are used to fulfill requirements for quality.
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Resident - Species which are permanent living members of a particular
Riparian area - Riparian refers to the area of land adjacent to a body of water,
stream, river, marsh, or shoreline. Riparian areas form the transition between the aquatic
and the terrestrial environment.
Riparian Forest Buffers - An area of trees, usually accompanied by shrubs and
other vegetation, that is adjacent to a body of water which is managed to maintain the
integrity of stream channels and shorelines, to reduce the impact of upland sources of
pollution by trapping, filtering, and converting sediments, nutrients, and other
chemicals, and to supply food, cover, and thermal protection to fish and other wildlife.
Roe - Fish eggs, especially while still massed in the ovarian membrane; called
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Salinity - A measure of the salt concentration of water. Higher
salinity means more dissolved salts. Usually measured in parts per thousand (ppt).
Salinity regime - A portion of an estuary distinguished by the amount of tidal
influence and salinity of the water. The major salinity regimes are, from least saline to
- Tidal Fresh Describes waters with salinity between 0 and 0.5 parts per
thousand (ppt). These areas are at the extreme reach of tidal influence.
- Oligohaline Describes waters with salinity between 0.5 and 5 ppt. These
areas are typically in the upper portion of an estuary.
- Mesohaline Describes waters with salinity between 5 and 18 ppt. These areas
are typically in the middle portion of an estuary.
- Polyhaline Describes waters with salinity between 18 and 30 ppt. These areas
are typically in the lower portion of an estuary, where the ocean and estuary meet.
Scavenger - An opportunitic animal that feeds on decaying plants and
animals or scraps of food abandon by other animals.
Scute(s) - Large dermal keratinous plates (i.e. the bony armor of a sturgeon).
Sediment - matter that settles and accumulates on the bottom of a body of water
Siltation - The process by which sedimentary material, or silt, is suspended and
deposited in a body of water.
Spawn - To release eggs and/or sperm into water.
Species - A population or group of populations that are in reproductive contact
but are reproductively isolated from all other populations.
Spicule - Small hard needle-like projections, often composed of calcium, silicon
and used for support in certain parts of some invertebrates such as sponges and corals.
Submerged Aquatic Vegetation (SAV) - rooted vegetation that grows under water in
shallow zones where light penetrates.
Substrate - "Supporting surface" on which a sessile organism
lives and grows. The substrate may simply provide structural support, or may provide water
and nutrients. A substrate may be inorganic, such as rock or soil, or it may be organic,
such as wood.
Suspended sediments - Particles of soil, sediment, living material, or detritus
suspended in the water column.
Storm Flow - rainfall runoff that reaches a stream channel during, or soon after
a rainfall event that causes high rates of discharge.
Stratification - The formation, accumulation, or deposition of materials in layers,
such as layers of fresh water overlying higher salinity water (salt water) in estuaries.
Swamp - a wetland dominated by woodsy vegetation.
Swim Bladder - an organ regulating the buoyancy in most teleost (bony)
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Thermocline - A specific depth at which there is a layer of water where the
temperature changes dramatically. Warmer surface water is separated from the cooler deep
water. This temperature gradient results in the formation of a density barrier.
Toxicant - A poisionous or toxic agent which is harmful to living resources
either terrestrial or aquatic.
Tributary - A body of water flowing into a larger body of water.
Trophic Level - Layer in the food chain in where one group of organisms
serves as the source of nutrition of another group of animals.
Turbidity - The decreased clarity in a body of water due to the suspension of
silt or sedimentary material.
Use attainability analysis (UAA) - A UAA is a structured scientific assessment of
the factors affecting attainment of the designated use component of water quality
standards, based on physical, chemical, biological, and/or economic factors.
Vertebrate - Animals with a backbone including fish, amphibians, reptiles, birds,
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Watershed - a region bounded at the periphery by physical barriers that cause
water to part and ultimately drain to a particular body of water.
Wetland - Low areas such as swamps, tidal flats, and marshes which retain
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Year Class - Most fish species in temperate waters (like those found in the
Chesapeake Bay and offshore Virginia) reproduce during a relatively short (one or two
month) period each year. That period may be different for each species. Fisheries
scientists refer to all of the fish of any species hatched during one annual spawning
period as a year class. For mathematical purposes, fishery analysts often treat members of
the year class as if all fish were hatched on one day.
Zooplankton - a community of floating, often microscopic animals that inhabit
aquatic environments. Unlike phytoplankton, zooplankton cannot produce their own food, and
so are consumers.
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