Glossary of Terms

Alkalinity -
A measure of a solution's ability to buffer or neutralize acids, measured in milliequivalents per litre as calcium carbonate.

Aquatic macrophytes -
Larger plants of fresh water which are easily seen with the naked eye, including all aquatic vascular plants, bryophytes, stoneworts and macro-algal growths.

Benthic -
Of, relating to, or occurring at the bottom of a body of water.

Brackish lake -
Lakes containing a mixture of fresh and salt water.

Bryophytes -
A collective term for liverworts and mosses - plants which are often abundant on exposed boulders and bedrock.

Catchment -
Drainage basin contributing water and sediment into a lake.


Charophytes -
A distinctive group of green algae (Characeae), known as stoneworts, which superficially resemble vascular plants in their size and the complexity of their structure. They are particularly associated with unpolluted waters that are rich in calcium.

Conductivity -
A measure of the ability of a solution to conduct an electrical current. This is related to the total ionic concentration of the water and varies depending upon the type and amount of ions present.

Dystrophic lake -
A nutrient-poor, highly acidic lake.

Emergent plants -
Wetland plants which typically have most of their leaves above water level, e.g. tall emergent species, wetland herbs and low-growing grasses.

Eutrophic lake -
A nutrient-rich lake.

Filamentous algae -
Aggregations of single-celled algae that grow in long strings or mats in water and are either attached or free-floating. Dense growths of filamentous algae are often associated with nutrient enriched waters but also occur naturally at lower abundance.

Floating-leaved plants -
Aquatic plants with most of their leaves floating on the water surface.

Lake Assessment for Conservation(LACON) -
LACON scores give an indication of the conservation value of a lake.

Marginal plants -
Wetland plants growing at or near to the margin of waterbodies in shallow water or seasonally flooded soils.

Mesotrophic lake -
A moderately nutrient-rich lake.

NE -
Natural England

NNR -
National Nature Reserve

NRW -
Natural Resources Wales

NVC -
National Vegetation Classification

Oligotrophic lake -
A nutrient-poor, typically peaty lake.

pH -
A measure of the acidity or alkalinity of a substance based on the number of hydrogen ions in a litre of solution. pH 7 represents neutrality, smaller values are acid, larger values are alkaline.

NSA -
National Scenic Area

PLEX -
Plant Lake Ecotype Index

Potamogetons -
A large genus of aquatic herbs (pondweeds) found in slow flowing waters; leaves usually float on the water.

RAMSAR -
Ramsar Site

Retention time -
The average time that water (or some dissolved substance) spends in a particular lake, calculated by dividing lake volume by flow rate.

SAC -
Special Area of Conservation

SNH -
Scottish Natural Heritage

SPA -
Special Protection Area

Species -
A group of organisms which resemble each other and which will not normally breed with members of another group.

SSSI -
Site of Special Scientific Interest

Submerged plants -
Aquatic plants which typically have most of their leaves below water level for most of the year.

Vascular plant -
Plants that contain the vascular tissues xylem and phloem. These include all seed-bearing plants and pteridophytes (e.g. ferns and horsetails).

Wetlands -
Habitats (e.g. marsh, fen, shallow temporary water) occupying the transitional zone between permanently inundated, and generally dry, environments.