Nature's Weirdest River Inhabitants

A small woodland stream. It gently meanders through the trees and carves its way between the rocks of the bubbling brook and the magical play of sunlight on the water. It's an enchanting and seemingly timeless scene and yet it's a world full of strangely exotic creatures. Curious fish that seizes anything which moves and others which flit about in colorful shoals. tiny fishing wrens and colorful summer visitors both above and below water some so alien and bizarre while others a distant childhood memory woodland stream and all along the banks of the stream trees are shedding their leaves it's the biggest annual delivery of food to the small brook at dusk stone crayfish emerge from beneath the rocks and at this time of year they have only one thing on their mind to find a mate the actual act takes place among the leaves and while some are still busy sealing their bond others are already carrying a precious load after mating it's back to the safety of the rocks the best hiding places are quickly taken smaller creatures also seek refuge in the shallows and provide food for those who can find it a dipper bravely dives into the turbulent water looking for small insect prey be adapted to swimming and hunting underwater. Waters also provide ideal conditions for brown trout which have moved upstream to spawn in the shallow gravel beds. Larger male quivers to indicate his intentions and encourage the female to release her eggs. His efforts have paid off and she starts to prepare the nest. The eggs and sperm are released simultaneously, and the female ensures that they are buried safely in the gravel. Her young fry will develop over the winter. By the time they hatch in early spring, there will be plenty of small plankton for them to feed on. For the kingfisher, prey continues to be available throughout winter. Water ensures that the stream hardly ever freezes, and it can carry on fishing whatever the weather. Winter comes spring. Waters of the bubbling brook never stop their flow. Its source lies somewhere underground, beneath the roots of the trees. Heated by the furnace deep within the earth, the warm water seeps out and creates a balmy microclimate. Tiny freshwater snails, barely two millimeters long, thrive in the wet warmth, feed on fallen leaves, disposing of any organic waste. The clean spring water also attracts small crustaceans. Freshwater shrimps graze on green algae covering the rocks, as do the larvae of caddisflies and mayflies. These tiny, alien-looking creatures all ensure that the waters of the stream continue to run clear. As the temperature drops further, a thin ice sheet forms over the surface of the brook. Water never freezes solid. The icy lid traps the warmth below. Nonetheless, in these frosty conditions, life within the stream comes to a virtual standstill when the ground thaws again the first signs of life appear brown caps of the velvet shank a winter mushroom scattering its spores into the wind scarlet elf cups also thrive in the mosses by the stream they provide a welcome source of food at a time when there is little else on offer emerges out of its burrow attracted by the seasonal delicacy. Another early arrival after the snow melt, fire salamander. Females have been carrying eggs all winter and now need the clear waters of the stream to give birth to their young. Young salamanders emerge as miniature versions of the adults with a pair of feathery gills for breathing. Warmer temperatures also attract others out of their winter quarters. A large European ground beetle, it hunts at night, both above and below water. Ferocious predator has become a rare sight in European streams, much like many of the native residents. Beetle is after slugs and snails, and other small invertebrates, which are abundant along the wet banks. Freshwater shrimp, with its powerful jaws, the beetle quickly disposes of this modest meal. Early spring, night temperatures still often drop below zero. As the damp air freezes, the trees and bushes are cloaked in a feathery dusting of ice. White hoarfrost marks the course of the stream and turns the landscape into a winter wonderland. Early morning sun soon melts away the ice. A flock of siskins has descended on the alder trees, attracted by their favorite food. No sooner have the seeds been harvested or fallen to the ground, the alders begin to bloom again. Flowers or catkins appear whilst the tree is still leafless. Within a few days, the male flowers burst open to release their pollen. They are neither showy nor perfumed because they are pollinated by the wind. Tiny, dust-like grains are picked up by the breeze, carried to the smaller female catkins, often on the same tree. As spring gains a foothold and the first green shoots appear, other creatures make an appearance in the brook. A male bullhead fish is on his way upstream to breed. He's searching for a hollow beneath a stone that will serve as a nest. And as luck would have it, this one already comes with a female. He makes a knocking sound to signal that he's willing to mate. Need clean water and flat stones to breed. They also depend on an ample supply of food. A carpet of microscopic algae covers the rocks. These single-celled organisms, invisible to the naked eye, provide food for many tiny animals and ultimately all life in the stream. Large amoeba feeds by engulfing the algae with its body. Between the rocks, freshwater shrimps and caddisfly larvae graze on the carpets of green. It's this rich community of invertebrate life that sustains the fish populations of the stream. Streams like this, with a healthy and flourishing community of life, are becoming increasingly hard to find. Clean water is crucial for their success. But overnight, this stream's clear waters have turned a murky brown. Within hours, hundreds of fish have met a torturous end. No press, a multi-sewage plant that emptied thousands of liters of waste into the small brook. Tragically, the rare and endangered bullhead fish is among the countless victims. Over a thousand of them are wiped out in a single night. The disaster doesn't go unnoticed. The local environment agency and farmers join forces to pump the polluted water out of the stream and spread it on surrounding fields. The rest is disposed of by nature. Surprisingly, within just a few days, the stream appears to have recovered and the first spring flowers emerge. Even the first fish have reappeared, swimming confidently upstream. Beneath the rocks, crayfish have laid claim to vacated territories, and a few bullhead fish seem to have survived the disaster and quickly seek out the best hiding places. With the warmer temperatures of spring, the pussy willows have come into bloom. Furry catkins of the male flowers unfurl and turn yellow with pollen. Its yellow color and early supply of nectar attracts insects which carry the pollen with them to the female trees. Small birds like blue tits are also enticed to the feeding station. In early spring, insect prey is hard to come by, but the birds can get all the energy they need from the rich supply of nectar. Female trees are less conspicuous. Their catkins are more resembling of greenish caterpillars. But visitors carrying pollen can expect an even greater reward of nectar here. Above water and below, the breeding season is well underway. A male bullhead fish is already guarding the eggs of two females. but that doesn't deter him from trying his luck with a third he's struck lucky again by turning on their backs the eggs and sperm are released upwards and stick to the underside of the stone a stone loach appears interested in the goings-on the inquisitive intruder is not tolerated for long despite the loss of so many fish during the sewage leak populations can recover because most fish lay hundreds if not thousands of eggs at a time. Why then is the bullhead fish disappearing from our streams? The answer lies in the surrounding landscape. Cow manure and other fertilizers are spread over our fields to increase crop production. Intensive farming practices spell disaster for our freshwater habitats. Runoff from the fields, particularly after heavy rains, washes the fertilizers into streams and rivers as a result most of the wildlife has disappeared recent research from Germany has shown that only one in a thousand streams is still in good health today the remainder have lost over 90 percent of their native species and this is likely to be reflected across much of Europe the high levels of phosphorus and nitrogen flushed into the streams through fertilizers bring about a dramatic change in the water nutrient-rich soup encourages the growth of green algae which soon cover the rocks in a furry mat while the algae may thrive few other organisms are able to survive fast-growing green filaments crowd the water leaving little space or light for others even microscopic plankton die-off because the chemical makeup of the water has changed the delic ate balance of the stream's ecosystem is quickly derailed winding its way through the agricultural landscape the stream has little chance of escaping the influx of fertilizers and chemicals this man-made landscape seems virtually devoid of wildlife but there are animals able to make a living here. Hare's spring is in the air and these normally reclusive animals have come out to partake in their mating rituals. That March hares are a sign that spring is finally here. The warmer temperatures also start to transform the landscape. The banks along the stream's edge are among the first to burst into bloom. Garlic mustard, with its distinctive scent, was one of the first species to be used in Europe by Stone Age man. It grows rapidly, shooting upwards and unfurling its small white flowers. Its roots produce chemicals that prevent other plants from growing, so it quickly takes over the ground. The dry stalks from last year provide shelter for a perfectly camouflaged cocoon. Warm weather acts as a trigger for its owner to break out of the shell. Female orange-tip butterfly. Closer to the stream, another chrysalis. This time a male with bright orange wingtips. Orange tips overwinter within their pupae, so can only survive if vegetation along the stream is left uncut. Garlic mustard provides everything they need. Adult butterflies feed on the flower's nectar. Once they've fueled up, they attach their eggs to a stalk so that when the caterpillars hatch, they won't have to travel far to feed. Near the source of the stream, others have given their young an even bigger head start. Clean water and woodland cover provide a home for more secretive creatures. Fire salamander gave birth to her babies here, but she now needs to replenish her own reserves. There's no shortage of slugs and worms in the damp moss, and plenty of places to hide among the tree roots and hollows. In the water nearby, her young offspring are learning fast. They've had to fend for themselves from the day they were born. Practice makes perfect when it comes to catching your own dinner. Further downstream, where the water was brown with sewage just a few weeks ago, the banks are erupting in bloom. The pink flowers of the Butterbur are a rich source of nectar for bees early in the year. The leaves of the Butterbur, almost two feet across, are among the largest of all native plants. Hiding beneath them is a curious-looking fish with a stubby nose, common nase. These fish used to migrate in huge numbers up our streams to spawn in the shallow gravel beds. Today, their numbers have dwindled to just a handful. Like many creatures once abundant in our streams, the nase depend on clean and unpolluted water. Fry graze on the short algae growing on the rocks, which are easily destroyed by chemicals and fertilizers. The devoted bullhead is still guarding his brood of eggs. Tiniest suspicious movement is detected and dealt with. His appetite has been suppressed by hormones, so he won't be tempted to eat his own eggs. Lucky for the caddisfly, dutiful father never strays far from his developing eggs and fans them with his fins to keep them aerated. One by one, the young fry wriggle free from their nest sacks. will soon be done. For the female crayfish, it's quite a different matter. She will have to wait for eight months before her eggs are ready to hatch. Longer than any mother in the stream, caterpillars of the orange-tipped butterfly are already busily stripping away their host plant. Green color allows them to blend into the foliage, making it harder for predators to spot them. After five weeks, the caterpillar starts to spin a silken thread and anchor itself to the stem. This girdle will be its lifeline for the coming year. Once the anchor line is firmly in place, the caterpillar can begin its remarkable transformation. It's a process that will take weeks as its organs are reassembled into the body of a butterfly. But it can only do so if the vegetation along the stream is not cut back. The grub's soft body hardens into a protective cocoon and takes on the shape of the seed pod of its host plant as trees and bushes burst into leaf. The small stream is shaded from the sun, so its shallow water remains cool. Perfect spawning conditions for brook lampreys. They gather in small groups, competing fiercely for the females. Mating in the fast-flowing water is a tricky balancing act. powerful sucker mouths help cling to the rocks while they deposit their sperm and eggs in the cool upper reaches of the brook the long wait is at last over the miniature crayfish have hatched tiny lobsters still shelter under their mother's tail she will protect them from hungry mouths for another few weeks before they have to fend for themselves by the end of May the trees along the stream are all in leaf. In the cool shade, its water remains rich in oxygen for what is the most colorful spawning migration of the year. Large shoals of minnows make their way upstream. They dart back and forth in a frenzy, the red-bellied males chasing the females to encourage them to deposit their eggs. Once fertilized, the eggs quickly sink into the gravel and the minnows are off again minnows and butterflies change into striking colors for spring some of the streams inhabitants only show their true colors at night hidden from our eyes an amazing show takes place under cover of darkness insect larvae and freshwater shrimp fluoresce when illuminated by blue light revealing their secret colors eggs of the crayfish glow like beacons a mysterious display that we still don't understand as it feeds tiny particles drift off in the current like underwater shooting stars sound of thunder signals the arrival of the first summer storms June is the wettest month for the woodland stream the heavy downpours bring an influx of fresh water and the small brook is transformed the stream turns into a racing torrent carrying vast quantities of sediments these will clog up gravel beds and suffocate tiny fish fry and crustaceans it's a problem that is magnified by the surrounding farmland flushing even greater quantities of mud into the floodwater while the rising waters are a challenge for some others are well prepared red ants bunch together to create a raft and float off to higher ground the raft comes to a stop its agile passengers climb up the grass stems to wait for the waters to recede again. Those that can fly have little trouble keeping their feet dry. The golden Oriole has built its nest high up in the branches, well out of the way of floodwater. Others seek out the safety of tree hollows along the water's edge. Woodlands alongside the stream provide plenty of insect food for raising chicks, so it's not surprising that the Orioles return here year after year to breed. Nest holes near the waterfront are always in demand. With several apartments in the same tree, disposing of the household waste is part of the daily chores. Nonetheless, some of it ends up in the water below. These natural nutrients are easily disposed of by the stream's filter feeders. It's the waste dumped here by man's activities which are the problem late spring one of these filter feeders puts on a dramatic show shelled river mussels have migrated to the edge of the stream to take part in what appears to be a choreographed water display in fact these female mussels are shooting their larvae into the middle of the stream tiny offspring will be picked up by passing fish and carried to a different part of the brook it's It's a strategy that allows the mussels to travel further than they could under their own steam. In the shallow pools around the brook, long-legged flies are dancing on the water, their metallic bodies glisten in the sun as they show off their long legs and wings, and it's all to impress the females. During the intermission, poolside snack to replenish energy reserves. The summer months are a time of plenty. A new generation of insect larvae are unleashed into the water, and even the bullhead fish regains his appetite. A pair of wagtails take advantage of the food supply to raise their young. A clean and healthy stream like this one supports a rich diversity of life. The wagtails have built their nest high up on the bank, out of reach of enemies and rising water. And right on their doorstep, there's an endless supply of flies and other insects. Warm summer's day, as the sun starts to set, the stream takes center stage for an annual event. In the light of the full moon, the show begins. Hundreds of thousands of mayflies rise from the surface. All year, they've lived underwater as larvae, but now their adult form takes to the air. They have just a few hours to mate and lay their eggs, and their frenzied efforts attract hungry fish from below. As the swarms become more and more dense, the struggle to stay airborne takes its toll. Before long, thousands of dead bodies litter the surface. It's a food bonanza for the fish. Mayfly populations have suffered from the influx of sewage into our streams. But with tighter regulations, they're now making a comeback. Streams and their wildlife are resilient and able to recover, if given the chance. All they need is a little space and safeguarding of their water. As the days of summer draw to an end, the frenzy of breeding is nearly over. Male banded demoiselles dance across the water, displaying their dazzling blue colors. A last attempt at mating before the season is over. The female injects her eggs into the stems of floating plants. With this final act, her short life is over. offspring, on the other hand, will develop underwater for the next two years, benefiting from a stream that is healthy and clean, and for the moment, still one in a thousand.