Water - In the beginning...

        Prior to looking at the other pages about habitats, plants and type of waters, let us overview 'water' itself.

Physical

• Buoyancy   Water is denser than air therefore giving a more buoyant medium exerting an upward push on all plants and animals. This gives way to delicate structures in the water plant world than terrestrial growth.
   

• Temperature   Water has the greatest specific heat of all substances, it can absorb a relatively large amount of heat for a small rise in temperature. Therefore giving a buffer against wide fluctuations in temperature which is why lochs and rivers
  vary relatively slowly. Cold water at 4^oC is at its densest and when the water becomes cooler in the autumn the
  upper surface sinks and displaces the warmer water from below. Water colder than 4^oC is less dense because of
  its structure change in its molecular structure and therefore floats to the surface, where further cooling creates ice.
   

• Pressure    Water is almost incompressible and there is therefore not a large increase in density with a depth increase.
  For every 10 metres that an object sinks below the surface the pressure upon it increases by one atmosphere, with plants
  and animals being able to adjust to suit their living environment and depth.
   

• Viscosity    Viscosity or internal friction of water varies with temperature. Water being twice as viscose near freezing point than at summer levels. This does affect small bodies in the rate at which they sink, and the ability to maintain their position in the water column.
   

• Surface Tension   This factor is very important physically to small plants, animals and the angler. Pond skaters can glide over the surface, snails can cling to the underside of the surface film. Hatching insects can become trapped in the surface film; especially on a flat calm day.
   

• Light      Water reflects more light than the land, furthermore light its energy diminishes with distance from the surface until there is virtually no light below a certain distance. Due to the different absorption of wave lengths by water the quality
  of light changes with depth. Water will absorb the shorter wave lengths of solar energy but within the range of visible light
  it absorbs the longer wave lengths more effectively. Light that penetrates the deeper parts of a loch is relatively poor in red and orange rays, the most effective for photosynthesis, but the light rays that do penetrate are rich in green and blue rays. 

Ecology - (A study of the inter-relations between living organisms and their environment.)
 

They differ from lochs (lentic environment) in a number of ways:

• a continuous one directional flow.
• variation in velocity with change in volume of water.
• wide range of fluctuations in water level.
• as a rule, shallower in depth compared to lochs.
• water confined to narrower channel.
• can increase in width, depth and length with age.
• permanent removal of eroded materials, which erode at one point to be deposited downstream with no opportunity for return.
• absence of  prolonged stagnation.
• there is a great dependence on food materials from surrounding land.

The main difference and most significant fact is that rivers and streams are open systems whereas ponds and lochs are closed or self contained. An important point is that lochs/ponds may use their nutrient materials several times a stream/river will only be able to use the food chain temporarily.

A river can be classified in two ways:

• its physical characteristics 
• by the fish species present.

The aquatic vertebrates will indicate the differing physical, chemical and biological features of the river.

The first classification can be broken down into three sections.

• Upper or mountainous course- fast flowing waters, especially after a downpour, can move large stones. this type of course runs through a V-shaped valley and has great powers of erosion.
• Middle course- the river runs over foothills where the water velocity is less causing a slower flow, but still fast enough to carry sand and silt in suspension and can also move pebbles along its bad. dependant on the surrounding land the river/stream can erode its banks with some devastation.
• Lower course- at this level the river meanders/zig-zags slowly across the plain. It has lost much of its velocity and the ability to carry anything in suspension (silt/sand) and lays it down creating a fertile plain.

The second classification breaks the river into zones, this being based upon the fish species present.

• 
  Headstream/Highland burns, formed usually by a number of small streams derived from either a spring, marsh or glacier. The stream is small, shallow and irregular in its course. It will be torrential to some degree with no pools and low water temperatures. Plant life is generally mosses and liverworts. There are no fish in this zonal area.
• Troutbeck, larger than the headwaters and more constant. A greater volume of water in this area erodes its way into the exposed bedrock. The flowing current is usually more rapid and deeper. The typical troutbeck is a steep gradient with its sides strewn with boulder/large pebble. Sheltered parts will hold heavy grit deposits. There will be little plant life due to the water current being strong coupled with the rocky environment. The water is always cold and oxygen saturated. Fish present within this zone are the brown trout (Salmo trutta) which are powerfull swimmers, the miller's thumb (Cottus gobio) and the stone loach (Nemacheilus barbatula). Their habitat is amongst the boulders and stones.
• Minnow/ Grayling zone, less of a gradient than the trout zone, therefore a slower current, although the water can still run swiftly. Less erosion is set up in this zone with some silt depositing in the quieter areas. With the quiet areas there is plant life, the water is still well oxyginated but temperatures will very more. Fish that are generally found within this zone are the minnow (Phoxinus phoxinus)  and in some areas, the grayling (Thymallus thymallus), trout also the eel and young salmon; depending on location.

Lowland course, the final stretch of a river/stream here the river is deep and slow moving. The result of the slow current is the depositing of the suspended silt forming a muddy bottom on which plants can grow. The temperature will vary and the oxygen concentration will be less than that of the other zones. Although some of the fish from the upper regions can be present conditions are not suitable for the successful completion of their life cycle. For example, the trout and salmon require silt free gravel in which to lay their eggs, also cold and well oxygenated water for the young fish. The conditions that this zone creates is more suitable for fish such as: roach (Rutilus rutilus),chub (Leusicus cephalus) an the bream (Abramis brama).

Not all rivers have these courses as the land formation is the defining factor. There are a lot other factors that come into to the formation of a river/stream and these come under the regime of man himself.

Ecology - (A study of the inter-relations between living organisms and their environment.)

Lochs & Ponds - Originate in various ways depending on how the basins were formed - circular. semi-circular, near rectangular or ox-bow. there are exceptions to these, such as: valley being dammed or waterways.

The interesting point of lakes & ponds from the fisherman's point of view is the depth and what happens during temperature changes; as this affects the salmonids. During the summer months and more so the deeper lakes/ponds can be divided into two layers due to the warming of the top layer by the sun during the calm periods. These layers are thermal stratification, the upper layer of warm water is known as the epilimnion  and the lower colder layer the hypolimnion and the area between the two is the thermoclin.

The graph shows the saturated oxygen at the varying temperatures which will affect the years angling i.e. the high and low temperatures make the salmonids lethargic and are put off feeding. The high temps have a lack of oxygen with the low temperature having an excess of oxygen.
Definitions of large water types - Oligotrophic, Eutrophic, Mesotrophic and Dystrophic.

• Oligotrophic - Usually deep waters, lie on infertile rock e.g. Granite. Poor in dissolved nutrients. These waters are generally found in mountainous areas with most of the lochs in the Scottish Highlands being if this type. Because of the low production of plants and animals oxygen depletion does not occur in the hypolimnion; this where in this cold water environment we will find fish such as the brown trout (Salmo trutta), char (Salvelinus alpinus).
• Eutrophic - These waters lie on a mineral rich rock, such as limestone, and are shallow with a large littoral area rich in flora and fauna. A eutrophic water are usually situated in low-lying farmland. Oxygen may become depleted in the hypolimnion during the summer. Although there maybe trout present within these waters, the conditions are generally not satisfactory for the completion of their life cycle. Fish of the carp family etc. are more prevelant.
• Mesotrophic - This type have characteristics lying somewhere between those of oligotrophic and eutrophic waters.
• Dystrophic - Found mainly in moorland, boggy an mountainous areas. Such waters are rich in organic matter consisting of undecomposed peat and other humic material. The waters are often stained a tea colour and the pH of the water is usually very low. There is very little decomposition because of a calcium deficiency.

Wind effects on large waters -

   Illustration of Langmuir rotations;
open circles=positively buoyant particles,
closed circles=negatively buoyant particles.

In exposed systems, wind can create turbulent, spiral-formed surface currents called Langmuir rotations.
Exactly how these currents become established is still not well understood, but it is evident that it involves some interaction between horizontal surface currents and surface gravity waves. The visible result of these rotations, which can be seen in any lake, are the surface foam lines that run parallel to the wind direction. Positively buoyant particles and small organisms concentrate in the foam line at the surface and negatively buoyant objects are found in the upwelling current between the two rotations. Objects with neutral buoyancy tend to be evenly distributed in the water column. This turbulence circulates nutrients in the water column, making it crucial for many species, however its effect on benthic and profundal organisms minimal is to non-existent. The degree of nutrient circulation is system specific, as it depends upon such factors as wind strength and duration, as well as lake or pool depth and productivity.

The Biology Page.                            

This page is designed to help in the understanding of life and life forms in our river systems, it is not a succinct scientific page as such, but a beginners starting point.
The Ecology pages, are kept separate from the Biology section as a different path will be sought.

The freshwater habitats are divided into two groups; Rivers and Lochs.

• Water - Make up
• Standing water - lakes and ponds
• Running Water- streams and rivers.
• Plant Communities - Freshwater plants

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Water has a tremendous fascination for most of us. We like to swim in it, walk by it or sail on it. There are many hobbies and pursuits which depend on it - fishing, sailing, canoeing, swimming and water skiing.
Each sport or hobby takes its sights further as they need to know more of  which gives them pleasure, e.g. The fisherman needs to know what insect lives within and around; the canoeist and yachtsman for the weeds and the rambler for the water birds and plants.

Water the life within. - There are many life forms in our water systems and they all go towards the life cycle of our planet; as we know life would not exist in the form it takes at present if water were not present.

• We often perceive liquid water (H₂O) to be ordinary as it is transparent, odourless, tasteless and ubiquitous.
  It is the simplest compound of the two most common reactive elements in the Universe, consisting of just two hydrogen atoms attached to an oxygen atom. Indeed, very few molecules are smaller or lighter. Water is the second most common molecule in the Universe behind hydrogen, H_2. To end the subject on water,
  water's unique properties and chameleonic nature seem to fit ideally into the requirements for life as can no other molecule.

Some H₂O life forms - Click drawings for further explanation. Video available.

Protozoa video		Flagellates (One of many.) (those that photosynthesise are often classed as algae).
Rotifers video		Wheel-like, hairy appendages, transparent, free swimming or attached.  0.2 - 1 mm.
Hydra video		Green, brown or colourless, body and tentacles contract and stretch can extend: 20 mm.
Arthropods  video		Jointed limbs; many groups e.g. crustaceans ('water fleas') mites. Picture of Cyclopsida.
Other: Insect stages		E.g. caddisfly larvae, dragonfly nymphs, water beetles, etc.
Alderfly nymph		One tail, long filaments along the abdomen.
Caddisfly larva picture		Most species build a cylindrical case for protection, other species make a distinct case from different materials.
Stonefly nymph video		Two jointed tails.
Mayfly nymph video		Three jointed tails, leaf-like (or other shaped) 'gills' on its sides. Picture of Baetis Nymph gills (mayfly).
Damselfly nymph video		Three leaf-like tail appendages (gills), extendable jaws.
Dragonfly nymph		Robust, no tail appendages,  extendable jaws.
Water bug nymph/adult video		No jaws, like all water bugs they possess a tube-like beak, the nymphs don't have wings.  Common forms: Backswimmer, Water boatman. Water surface: Pond skater.
Water-beetle larva		Strong jaws, long segmented body, short legs.
Water beetle adult		Strong jaws, tough shield, many water beetles are fierce predators.
Drawings by kind permission of -         Wim van Egmond		For further information - Web Site: www.microscopy-uk.org.uk

Animals of the lotic and lentic regions.

LOTIC   

Where it is rapid streams with stony beds (eroding substrata) most animals are bottom living, surprisingly this type of water most often produce the largest variety of bottom living organisms. Limpet, leeches, flatworms, black fly larva and a variety of mayfly nymphs and stoneflies. The freshwater shrimp lives in crevices in the stony river base to which they adjust to the streams current as do the other insecta of fast waters.

Depositing substrata:
                                Depositing substrata consists of sand or soft silt which is the least favourable for animal and only will support the smallest number of species. The surface will hold animals such as the water louse (Asellus), the alder fly larva (Sialis), various snails (Valvata & Bithynia) and in the silt the pea mussel. The substratas with lower oxygen content you will find e.g. Tubiflex & Chironomous).

LENTIC

A stony shore line is similar to the eroding substrata of running water, due to the wave action.
The species of animals found in lochs or lochans are not always the same. For example a species of mayfly with the genus Ecdyonurus can be found in both lotic and lentic waters the other two species are only found in rivers. Further out beyond the shore line (littoral area) is the offshore area (limnetic zone), this area is generally made up of fewer animal species but in much greater quantities.

Scotland’s rivers are mostly unpolluted - 92% were classified as good or very good condition by SEPA in 1996. As clean river water is very important for Scotland’s industries, tourism and recreation if the river has not been managed well, good water quality will be lost.
There is a wide range of threats to river habitats in Scotland: flood control, land drainage work, erosion control, culverting, straightening field boundaries, ploughing and spraying river banks and heavy grazing by cattle and sheep; which will not allow the angler good fishing or protection of the wildlife in and on our rivers.
It is important, therefore, to protect river beds and banks, as well as the quality of the water, if we want to ensure that Scotland keeps its high quality river environments for generations to come.

 

River Management	What makes a good river manager?	Duties of a manager.	Problems which can occur.	Human pollution.
Blockages.	Natural blockages.	Blockage cleared.	2 Years later.	Major blockage.
Partially clear.	Man made obstructions.	Impossible weir.	Fish ladder.	Compacted river bed.
Erosion & bank collapse.	Using natural materials.	cont'd.	Deflector 2 years on.	Conclusion.