Hand nets are most commonly used for 'dipping' in ponds to assess what wildlife inhabits its waters. Hand nets need to have a sturdy long handle and with a net bag of the correct mesh size for your studies. Professional nets have 1mm mesh which is good for general invertebrates or 2/3mm mesh more suitable for amphibian work. They are also available with smaller mesh bags (250 or 500 micron) for collecting larger zooplankton. Smaller, lighter hand nets are suitable for students, children or in restricted sites.

When out water sampling with hand nets it is advisable to equip yourself with the following items.

Wellies/Waders - for the obvious reason, to keep your feet dry! Waders are more suitable when having to venture further into the water. But take care as it can be easy to get stuck in silt/mud when wading out too far into a pond.

White Trays - good for emptying and sorting a catch

Hand lens - x10 or x20 are helpful for identification purposes.

Field guide/chart - to aid with identification of species caught

A bright torch is also a useful tool - used at night to illuminate the shallows can often allow you to see species of newts, diving beetles and fish which may have evaded your nets. One disadvantage is that it can be difficult to identify species positively using this method.

In addition to hand nets, there are a variety of specialist nets used in biological water sampling.

Plankton nets are made out of the finest meshes to catch plankton and other minute water-borne organisms. Again, choose the right mesh size to suit your studies - 250 micron is suitable for zooplankton and 53 micron for phytoplankton.

These nets are towed behind a boat or cast out into the water and dragged back from the waters edge. A known volume of water can be passed through the net for population/concentration calculations.

As the water passes through the net, the plankton are collected at the bottom by a filter which can then be detatched and the organisms studied. Some people merely wish to see what is present in a water body and can just wash the catch into a Petri dish. This Petri dish can then be studied under a microscope - x40 or more magnification and a polariser is recommended for this. For assessing concentrations of plankton you need to wash filter thoroughly with a known volume of water. A small known amount (e.g. 1ml) is then transferred into a well or cell slide for counting under a microscope and calculating the population.

Drift nets are for collecting drifting organisms in shallow flowing water such as streams or rivers. The are staked down below or at the surface or the water. They can be used singly or set up in a line (useful for studying a cross section or a river). It will catch any creature that has been dislodged or migrated from the bottom - these drift organisms are critical to stream/river ecosystems. Looking at their levels can often help with trends in populations of the fish and other species which feed off them. They can also been helpful in assessing pollution effects on the water's ecosystem.

Surber nets are suitable for quantitative sampling in waters flowing less than about 10cm per second. Once set down on the stream bed, disturb the silt and over turn any rocks within the area of the frame. The dislodged organisms will then float down stream and be collected in the net. You can get a choice of net mesh sizes - 1mm for general invertebrate work and 250 micron for collecting even the smallest of invertebrates.

Kick nets are often used in sampling invertebrates in shallow, fast flowing streams and rivers. One person secures the net downstream, making sure the bottom of the net is tight against the streams bottom substrate. Another person then disturbs the substrate (turning over any stones) in about a metre area in front of the net. Then with a scooping motion lift the net from the water collecting all the creatures disturbed and trapped on the netting.

In addition to nets, various other tools are used to aid biological water sampling.

Colonisation samplers are designed for sampling macro-invertebrates in deeper, slow flowing waters. These are simply secured at the bottom of the river for 4 to 6 weeks and then collected and invertebrates which colonised the samplers can be identified and counted. The species and abundance of the invertebrates which were able to colonise the samplers will directly reflect the water quality of the sampling site.

These come in multi prong and rake-like designs and are used for basic sampling of larger aquatic plant (macrophytes). They can be simply thrown and dragged back from a boat or the shores edge - any plants it passes through will be snagged and dragged back for identification. Using a grapnel for sampling can be limiting as smaller species are often missed and even some species of macrophytes can be difficult to snag using this method. Care should be taken that the sample area does not contain rare or legally protected plants as this is a destructive method of sampling.

Secchi plates are used to measure the turbidity or transparency of the water. Transparency indicates levels of substances in the water body such as algae, pollutants or humus. The plate is simply lowered straight down into the water until it can no longer be seen. The rope is then measured to give you the secchi plate's depth and therefore a relative reading for turbidity.

Flowmeters are devices for calculating the flow velocity of a stream or river etc. They can be used together with nets such as the drift nets to calculate the volume of water flowing through the net in a sample.