Fish and Pollution - Glossary

Index

A • B • C • D • E • F • G • H • I • J • K • L • M • N • O • P • Q • R • S • T • U • V • W • X • Y • Z

A

Acid rain - due to air pollutants like nitrogen and sulfur oxides, the rain in some areas has an unusually low pH.  This low pH, or acid, rain can cause the pH in streams and other water bodies to fall below the level that is safe for fish and other aquatic organisms.

Alkaline - a term generally used to describe a substance that is basic or has a high pH.  In chemistry, the term alkaline is used to describe a solution that has more hydroxyl (OH^-) ions than hydrogen ions (H⁺).

Anadromous - this is a characteristic of some fish like salmon and sea-run trout which spend part of their life cycle in freshwater and part of it in the ocean.  After maturing in the ocean, anadromous fish return to freshwater to spawn.  When the eggs they lay hatch, the young fish migrate to the ocean.

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B

Buffering capacity - the ability of a water body to resist large changes in pH when an acidic or alkaline solution is added to it. The buffering capacity of natural waters can be exceeded by industrial discharges.

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C

Catchbasin - an underground barrel that collects street runoff water via a street drain before discharging the water into a storm sewer pipe.  Materials deposited into a catchbasin on a dry day could be flushed out into a creek the next time it rains.

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D

Deleterious - As defined by the Fisheries Act, a deleterious substance is "any substance that, if added to any water, would degrade or alter or form part of a process of degradation or alteration of the quality of that water so that it is rendered or is likely to be rendered deleterious to fish or fish habitat or to the use by man of fish that frequent that water."

Dissolved oxygen - the supply of oxygen (or O₂) in water is called the dissolved oxygen content.  Aquatic animals like fish and insects need to breathe oxygen just like humans do.  What is different about fish, though, is that they have to take that oxygen from the surrounding water.  They do this by passing water across their gills where the oxygen can travel from the water into their blood stream.  Oxygen gets into water through physical mixing (caused by waves or rapids) and photosynthesizing plants.

Dry ice - frozen carbon dioxide.  Dry ice can be used to "neutralize" a high pH or alkaline material.  It is more difficult to use than CO₂ gas.

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E

Ephemeral - lasting a short time.  An ephemeral stream may have water in it during the rainy season but dries up when there is little rain.

Estuary - the place where a watercourse flows into the sea. The saltwater tides mix with the freshwater outflow creating a region of variable salinity (often called brackish water) and a unique ecosystem. Salinity, tidal action, and freshwater outflow are all variable, resulting in a wide range of conditions and diverse micro-environments, which support a diversity of plants and animals. Estuarine species are often limited to specific micro-environments and areas within the estuary. Estuaries are important rearing and transitional zones where juvenile salmonids adjust from living in freshwater to living in the sea, and grow in size prior to heading offshore to the open ocean.

Exposed aggregate - this is a type of finish for concrete.  After the concrete is poured and has set for a number of hours, the top layer is washed off, exposing the aggregate, or gravel, in the mix.

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F

Fish habitat - the Fisheries Act defines fish habitat as "...spawning grounds and nursery, rearing, food supply and migration areas on which fish depend directly or indirectly in order to carry out their life processes..."  This includes where fish physically live at any time in their life cycle and areas where a fish's food may be produced (see Fish and Fish Habitat). 

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L

Large organic debris - fallen dead trees and snags, eroded tree roots, and logs.  These provide stream bed stability, cover and habitat for young fish.

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M

Migratory habitat - watercourses that are important travel corridors for fish migrating between the ocean and spawning/rearing grounds.

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N

Nutrient - compounds like nitrogen and phosphorus are important for plant growth including in aquatic environments.  Excessive amounts of these nutrients, however, can cause a proliferation of nuisance plant growth which can choke a stream channel.  As well, when the plants die, the decomposition of the plant tissue can rob dissolved oxygen from the water (see oxygen demand).  Chemical fertilizers and manure are potential sources of nutrients to streams.

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O

Over-wintering habitat - after emerging from the spawning gravel, the young of some species of salmon, most notably coho, move to sheltered, slow-moving areas of streams for the first year or two of their lives.  During the winter, this may include seasonally flooded areas or ephemeral streams that only have flowing water during the rainy season.  In spring the juvenile fish leave their winter habitat to migrate to the sea.

Oxygen demand - the organisms that break down organic matter (like leaf litter or animal wastes) consume, or "demand," oxygen during this process.  When the decomposition process happens in a watercourse, the oxygen is consumed from the surrounding water.  If there is too much organic matter in a watercourse and the oxygen demand is too high, there may not be enough dissolved oxygen for other aquatic organisms like fish to survive.

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P

pH - pH is how we quantify the content of acid in a sample.  The pH scale goes from 0 to 14, where 7 is neutral.  A low pH value means the sample is acidic, while a high pH value means that the sample is basic or alkaline.

pH pen - a portable meter used to measure pH.  These are available from chemical and scientific supply companies.

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R

Rearing habitat - small streams, back channels and lakes where young fish may spend up to two years (depending on the species) feeding and growing before migrating to the ocean.  Juvenile salmon may rear in different streams than they were born in, including ephemeral or seasonally wetted watercourses.

Riparian zone - the band of land beside a stream or other waterbody.  A well-vegetated riparian area is important for a number of reasons.  The root systems of stream-side plants provide stability for the soil, helping to prevent erosion.  The overhanging plants provide cover for protection, shade to maintain cool water temperatures, and food for fish and wildlife.  Stream-side plants also help to filter surface water flows to water bodies, especially sediments.

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S

Salmonid - a group of fish that includes salmon, trout and char.  This group belongs to the family Salmonidae.

Sedimentation - the process of silt and other sediment settling onto the bed of a creek.  Sedimentation can smother incubating eggs and fish food-organisms that live on the surface of a stream bed.

Street drain - street drains collect water runoff from streets and drain to storm sewer pipes (see catchbasin).  Most all street drains go to the nearest creek.

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T

Total suspended solids - a measure of the particles mixed in the water column (reported as a concentration, usually milligrams per liter - mg/L - or parts per million - ppm).

Turbidity - a measure of how cloudy water is.  Suspended particles in the water scatter light, preventing light from reaching the plants that convert the sun's energy into food, and impairing the ability of fish like salmon from seeing their prey.