Habitat Explorer

Rivers, Ponds and Lakes

Nick Baker

Dedication

I dedicate this book to my friend Sue Daniells, an adult who should know better!

For many fascinating hours pouring through the sludge in the bottom of countless pond nets.

Contents

Cover

Title Page

Dedication

Freshwater habitats

Puddles

Ponds and lakes

Rivers and streams

Boggy, soggy bits

Going further

Index

Author’s acknowledgements

Copyright

About the Publisher

Freshwater habitats

Life needs water and so wherever water accumulates on the planet’s surface, life tends to concentrate; whether it’s something as temporary as a puddle or as vast as the ocean. In this book I concentrate the naturalists’ explorations on those readily available pools of freshwater – puddles, ponds, rivers and bogs – focusing on ways to explore the moist worlds and the creatures they contain.

There is no supply of new water on our planet: the water we use has been used and re-used for millions of years. When water is heated it evaporates (like steam from a boiling kettle) and rises until it cools and turns into clouds. These clouds burst when they get too heavy, releasing their vapour as rain falling to the ground. This flows into rivers, lakes and seas, from where the whole cycle starts again.

From puddles to lakes, ditches to rivers, bogs to mires and water butt to fish tank, each contains a whole world of the weird and wonderful, unusual and fascinating. Whether you choose to dive into all the activities I have pulled together from years of being an avid pond dipper or whether you are just looking for a cool way to spend an afternoon, hopefully a page or two will catch your imagination and you will never look at a frog or a water beetle in the same way again!

Different kinds of freshwater attract different kinds of life, which have tuned their lifestyles and body shapes to the challenges that each habitat contains. Life in a pond may look similar to life in a stream – and there may well be overlap for some animals and plants – but look closer and more often than not, the animals and plants differ quite a lot from one another.

The differences are reflected within the pages of this book and broken down into corresponding chapters that deal with each. Many of the activities, however, are not necessarily exclusive to each habitat, so go out with this thought in your mind: ‘Eyes peeled, mind open and net and jam jar ready’ – and enjoy getting wet and muddy.

A boggy bit of land, swamp and marsh may not have much water that is obvious, but the puddles that do exist are often home to some very rare and specialized creatures that can handle the slightly more acidic conditions.

It doesn’t have to be a natural water body to be of interest to wildlife; a simple water butt or a cattle trough will appeal just as much.

This slow-moving mill pond has a rich growth of water weeds and is home to a mixed bunch of animals, some of which are found in both flowing and still water.

A bag of holes!

Naturalists and nets go together like sharks and teeth! They are simply very useful extensions to the human body and allow us to touch places that would otherwise be hard to reach. Nets become the means by which we enter another world. Because of this, there is a responsibility and a code of conduct that should be followed to avoid unnecessary suffering and discomfort to your subjects.

Whatever net you are using, at some point you will have to lift it clear of the water. As soon as the water has drained through the holes, any living things in the net are going to start feeling uncomfortable. So handle and sort the contents as soon as possible. Some creatures, such as adult water insects, are OK for quite some time but other creatures, such as fish and tadpoles, need water to breathe and will also dry out and dehydrate very quickly.

You must make sure EVERY living creature is happy and reasonably content submerged in water – in tubs, buckets, pots and trays – before you start observing any of them.

Nets are invaluable to the water naturalist, but you need to use them in conjunction with a tray or tub. This is so you can sort through what, at first hand, often appears to be nothing but a mass of sludge.

Once you have got a net full of good stuff, it can seem a little daunting peering into the mud, muck and weed and this is where a white tray comes in handy. As soon as you have removed your net from the water, support the bag with one hand and carefully turn it inside out into your white tray already filled with water.

It may still look like a bit of a mess, but spread everything out and let it settle down and from the murk you will start noticing movements as a dragonfly larva stumbles out of the silt or a worm starts wiggling! Now you can start redistributing various creatures into other pots for observation.

Remember to separate predators from prey as in close confines creatures cannot necessarily escape and you end up with a gladiator-style showdown. Not pleasant.

Do not leave specimens in the sun as water temperatures will rise very quickly. As this happens, not only will your creatures – which are totally your responsibility – start to cook, but long before that the water will lose its oxygen and creatures that use gills to breathe will start to suffocate.

Take my advice

* Pond dipping is more than sticking your net in the water and stirring everything up! In fact, doing this is one of the most common mistakes you can make. When approaching any water, keep quiet and move slowly and you can be rewarded with a shy fish basking in the shallows, a frog resting at the surface, a heron fishing or even a nervous water vole.

* Once at the water’s edge, stop and peer into the water to get an idea of what sort of animals you might catch. You may even be able to gently catch an individual there and then without causing too much disturbance.

* Only once you have assessed the habitat is it time to dip your net – gently and carefully. Keep water flowing through the net’s mesh. Move it slowly through the water, but not so slowly that even the slowest beetle can swim out the way it came in! A figure-of-eight pattern is perfect.

Handy stuff: making a net

You can buy a purpose-made net and there are many different kinds to choose from, but it is fairly easy to make your own basic one, which will then be useful in most situations.

The two most important ingredients of a net are the netting itself and the wire surround. For the netting, you want something that is white and of a reasonably fine mesh. White is best because with a dark mesh, too many creatures, even the ones with bad eyesight, stand a chance of seeing you coming!

The holes in your net must be big enough to let the water pass through and drain out easily, but at the same time not so big that all the little creatures get through. It also needs to be robust, otherwise you will forever be replacing the torn bag. I find a tough, coarse cotton fabric is one of the easiest and most practical types of fabric to work with.

Because the wire needs to survive a bit of a bashing, it is best to use a heavy-duty wire that takes a bit of effort to shape. The shape of the net mouth is entirely up to you some people like to have a flat edge, which makes working along the bottom of a pond or river easier. You could otherwise choose to make a circular one.

YOU WILL NEED

> some suitable netting

> needle

> thread

> strong but bendy wire

> wire cutters

> pliers

> bamboo cane

> gaffer tape

1 Decide on the depth of your net. Aim for it being about as deep as it is wide and allow extra fabric to fold over at the top a couple of times. Stitch the turned-down fabric to make a channel. Fold the fabric in half. Stitch along the bottom and up the open side as far as the channel and turn the inside out.

2 Thread the wire through the channel at the top of the bag. For size, you should aim for 20–30cm across. Anything bigger may seem like a better way of catching more, but get a big net full of weed and mud and nobody but Mr Universe would be able to haul the thing in!

3 Cut off the excess wire so that you are left with 7.5cm sticking out at each end. You might want to ask an adult to help you with this next bit – twist together the ends of wire. Pliers can be helpful.

4 Push them into the end of the bamboo cane and . . .

5 . . . use a good length of gaffer tape to keep the cane in place. Now you’re ready to dip!

Handy stuff for exploring with

A naturalist needs nets and they come in different sizes and styles for different jobs. A stout-framed one with coarse netting is perfect as a pond-dipping net; a lighter one with a delicate mesh is handy for catching winged creatures. A butterfly net is useful for catching . . . well, butterflies!

Binoculars These are expensive and one of the few things that you cannot make yourself. But they are well worth the investment and there are many prices to meet different purses. They are especially useful for bird watching, but a close focusing pair are brilliant for watching dragonflies.

Bucket Great for the bigger stuff.

Magnifying lens Another bit of kit that is worth buying. It will turn a mite into a monster.

Plastic pots, trays and plastic aquariums Brilliant for sorting, separating and observing your catches or collecting your specimens in. The clear ones are even more useful in a watery environment as they let you look at the animals from under the surface. Bags are handy lightweight alternatives to pots; they are also useful for keeping plant specimens fresh.

Sieves and tea strainers These are very handy for smaller, close-up work and sorting out creatures once you have caught them. Make them even more useful by strapping the handle to a bamboo cane with gaffer tape (see page 8), rather like the yogurt pot on a stick on page 31.

Stout stick I find this useful as an extra leg, especially when wading. You can use it to test the water’s depth or if you are leaning out with your net, a stick is something that you can lean on for support. With a little tape or string, you can construct a makeshift net handle, too.

Wellie boots Okay, so they aren’t fashionable, but they are a lot cooler than a shoe full of squelchy water or mud.

Puddles

Have you ever left a bucket of water out in the garden or peered into a water butt and noticed it full of wiggly things? Life has appeared as if by magic where before there was none. But this is far from a spontaneous happening. What you have just seen is the wonderfully efficient way that nature has of seeking out and colonizing a new habitat. Even a puddle, assuming it doesn’t just evaporate before things get going, can be home to all manner of weird and exciting life forms.

Try this experiment. It is called Thienemann’s tank and is named after a German scientist who first noticed this phenomena in his garden. Mr Thienemann set out to look at how aquatic invertebrates (that’s to say, those animals without a backbone that live in water) colonize watery habitats. He left a tank of water in his garden and then every now and again checked it for life. Over eight years he recorded 103 species, which turned up without any aid.

Many species, such as mites and snails, can hitch a lift on others, and some, such as beetles, bugs and dragonflies, all at some stage in their lifetime have wings that enable them to disperse and colonize fresh habitat. But some of Mr Thienemann’s finds were totally aquatic – they could only survive in water. So how did they get there?

If you try Thienemann’s experiment, you will be creating a new habitat. The method is simple – take as big a tank or tub as possible and fill it with water. Then check it every week and record everything you see living in the water. You will almost certainly need the help of a good field guide or even your local museum to help you identify everything.

You must also look very carefully as some of the creatures will be very small and not at all obvious at first glance. If you have a hand lens or a microscope, this may come in very useful. Try to keep a diary. Draw pictures of anything that arrives and add the date when you noticed it.

Some amphibians, particularly toads, can breed in surprisingly small puddles of water.

Water fleas, or daphnia, are not fleas at all; they just twitch and jump about like them. They are one of the most common of the freshwater crustaceans.

Mosquito larvae are very quick to colonize tiny little puddles and pools of trapped water. The contents of water butts, old car tyres, even jam jars, soon start to twitch with the eggs, larvae and pupae of this infamous insect.

Water boatmen, like many adult water insects, actually have wings folded away and are excellent aeronauts. This means they are some of the first colonizers of a new pond, magically appearing, seemingly out of nowhere.

Aeronauts and aquanauts

Now you can understand how tiny little things like water fleas can turn up in a puddle, but what about larger pond life, such as beetles, water boatmen and pond skaters? If you look in a newly dug pond or a cattle trough, you are more than likely to see a multi-eyed, six-legged water bug go rowing past. How did it get there? Well, wonder no more; the answer is that it arrived by air. To prove this, follow the steps opposite.

Some aptly named water boatmen – their back legs look like oars and bodies like hulls.

Fab facts

* These insects are thought to be very sensitive to the kind of light that is reflected off the surface of water, such as ponds, lakes and streams. So when they go buzzing about above us in the air, how do they find their new home? It turns out they are able to see the light as it is reflected from the water’s surface.

* The sad thing is that this worked perfectly well before mankind came along and confused things! Car bonnets and roofs look similar to water as they reflect the same kind of light and many pond insects, including water boatmen and water beetles, try to touch down in our car parks and on our roads – both fairly unfriendly places to end up dazed and spinning on your back!

1 A big water boatman is an ideal insect to catch. It is big, so you can observe it a lot easier, and it is also easy to identify as an adult. Water boatmen are the ones with the silvery white backs, which is easy to see when they are flipping around in your net.

2 Gently remove the insect from the net. Try to lift it without squeezing, as it can deliver a painful bite with its stabbing mouth parts. Hold it in the flat palm of your hand. It may leap about a bit at first, but it isn’t in pain, or suffocating – trust me!

3 It will soon settle down with it’s back facing up, so watch it carefully. The next bit usually happens in a couple of minutes, depending on how sunny or hot it is. Watch for it to open the top of its back and start pumping its abdomen back and forth. Any second now, the boatman will unfold its wings and buzz off to find a new pond. The mystery is solved – most adult bugs have leathery wings and are good fliers. This is handy as they can check out new homes, or simply make the most of temporary ones!

Take it further

* This is just a fun little experiment that helps us know how water boatmen, also known as backswimmers, orientate themselves in their underwater world.

* Take a small jar of water with your boatman in it to a dark room. Turn out the lights and shine a torch in the jar from underneath. What happens? Your water boatman – and here you must remember its other common name – has become a front swimmer. This proves they use light direction to orientate themselves in the water and not gravity.

Handy stuff: an aquarium

Scooping some strange and alien life forms out of the water, looking at them for a few minutes in a tray and then putting them back can be just a little dissatisfying. Yes, if you are lucky, you may see gills twitch, a bit of scrabbling around and, if you are a good naturalist, you may be able to put a name to the creature. But surely there is more to their lives than just that? How fast do they grow? How do they eat? Do they change colour? What do they turn into?

With just a bit of knowledge about how to set up an aquarium properly you can take a little piece of the pond or stream and some chosen subjects back home with you. It is only by gazing into their wondrous little lives day in, day out that you really get to know them and study them properly.

Remember, however, that once any living creature has been lifted out of its home in your net, it is your responsibility. Be sure not to over-stock your tank and not to mix predators with prey as almost certain carnage will result. It’s all about balance. Try to resist having too many individuals of any one species. One or two snails are good, but if they get happy, they will breed and eat all your plants. Lots of predatory fish or beetles look good, but may kill other, more delicate, creatures.

Do your research about the food requirement of your captives and look after them. If they are not looking happy, then you are probably doing something wrong. If this is the case, release your inmates back where they came from and think about your set-up. Adjust the tank accordingly and try again with fresh specimens.

Here is the great pond snail – it’s looking great indeed.

YOU WILL NEED

> fish tank

> gravel

> weed

> pump (optional)

1 A water-tight tank with clear sides is the minimum requirement. I prefer glass ones as they do not scratch or discolour, but they can chip, crack or smash if you are not gentle, and plastic ones are so much cheaper, lighter and readily available.

2 The next consideration is the type of water environment you are trying to recreate. If you are studying pond creatures for just a few days, all you really have to do is fill the tank with water and a few weeds and watch.

3 But if you are keeping your creatures for any longer, some gentle filtration and water circulation is a good idea. This keeps the water from becoming stagnant, ups the oxygen levels and removes and prevents a build-up of harmful substances. All this can be provided by an in-tank filter pump, again relatively cheap and available in many sizes, depending on the size of the tank it needs to filter. For species that live in running water, you may need to have quite an aggressive water flow, but the principles are the same.

4 Use rain water or water from where you got your creatures. Tap water can be used, but as there is added chlorine, it needs to stand for a few days before putting in your catch. Ideally, set up your aquarium a week in advance of adding them.

Make a micro zoo

The thing about ponds and lakes is that they are busy with life. Because they are so chock-a-block, competition for resources, like space and food, is intense. Puddles, on the other hand, tend to dry up from time to time and so are relatively empty. Now, to any creature this represents a challenge: to get life in a puddle licked you must have a speedy life cycle. You must be able to adapt so you can handle the extreme and often rapid changes in temperatures as well as sometimes very salty conditions. Do this, and you have the place pretty much to yourself.

Yes, puddle life is tough. But there are some creatures that have become puddle specialists. A couple of groups, such as the tadpole shrimps (or triops) and the brine shrimps, are rare in the wild in Europe, but they can be bred in captivity relatively easily. This means that you do not have to go out looking for them, but can actually buy them as eggs (see page 71) and rear them as a micro zoo or go pond dipping and see what you can catch (see opposite).

In the wild, these animals whizz through their life as soon as rain water fills the dents and the depressions that become puddles. They grow and filter out any nutrients from the mud and water (algae and various microscopic creatures are also quick to colonize these puddles). In fact, they can turn their lives around, from egg to adult to egg, in less than two weeks!

When eventually the puddle disappears, every creature dries up and becomes dust too. It sounds harsh, but this is dust with a difference – it’s living dust. In the dried-up mud they will have laid eggs and these minuscule capsules of life are able to withstand incredibly hot, dry conditions and so sit it out, waiting for the next downpour – and around they go again!

A hugely magnified triops, which springs back to life once you have nourished it with water and food.

YOU WILL NEED

> fine net

> plastic container with lid

> small pipette or plastic syringe

> collection of small jars or test tubes

> magnifying lens

1 Take your fine net out to a pond near you. Try to choose one with good clear water and go hunting on a bright day. All the creatures should be near the surface, making the most of the warmer water. Put your catch in a plastic container with a lid and take it home.

2 Once you’ve got home, use a pipette or spoon to sort out the truly tiny creatures from the slightly larger ones. It is the smallest ones that you want to keep for your micro zoo. There wouldn’t be much point in calling it a micro zoo otherwise.

3 Keep your super-small finds in a test tube or a similar lidded container and feed them regularly with green water (see page 21).

Take it further

Sometimes you will come across something in your catch that doesn’t belong to your micro zoo, but is nevertheless worthy of investigation with a magnifying lens. Here we found a snail egg case on a stick – all the little dots are the newly hatched snails that are crawling around (see also page 35).

Feed your micro zoo

The problem with having traditional pets is that there is not a lot of mystery surrounding their lives. You can buy books on how to keep them, so the challenge simply isn’t there. This is where my idea of the perfect pets comes in – the micro zoo that we created on the previous page. They are small, easy to keep and they won’t leave unwanted hairs on the sofa. In fact, as they are so small, you can build up a collection of them.

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