Skomer Marine Nature Reserve

skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 1 Skomer Marine Nature Reserve Stars, squirts and slugs... marine life in an underwater refuge skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 2 The Countryside Council for Wales is the statutory adviser to government on sustaining natural beauty, wildlife and the opportunity for outdoor enjoyment throughout Wales and its inshore waters. With English Nature and Scottish Natural Heritage, CCW delivers its statutory responsibilities for Great Britain as a whole, and internationally, through the Joint Nature Conservation Committee. ISBN: 18-6169-113-0 CCC : 208 Cover illustration: Seaslug Coryphella browni Inseide cover: Spiny starfish Marthasterias glacialis All the images and information in the booklet are the products of the work CCW staff carry out in looking after the MNR. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 3 Stars, squirts and slugs Wildlife of the Skomer Marine Nature Reserve Imagine a world where stars, squirts and slugs all exist side by side. Such a world exists in the Skomer Marine Nature Reserve (MNR), although here the stars, squirts and slugs are forms of life and perhaps not familiar to many. The stars are the many relatives of the common starfish: sunstars, bloodstars, brittlestars, spinystars, cushionstars and featherstars. The squirts cannot be compared to anything on land - most look more like miniature hand-painted jellies and flower heads than animals. And the slugs are tiny, voracious predators which are infinitely more colourful and attractive than any garden slug. But there is much more to the Reserve. The wonderfully scenic coast and seabed provide an abundance of different habitats - places for animals and plants to live - and they are teeming with all kinds of life, not just the familiar seals, fishes, crabs and lobsters. The Reserve is home to more than a third of all British algae (seaweed) species, over 75 different sponges and 40 species of anemone and soft coral. It is the great variety and abundance of animals and plants which makes this area special. Each fits into a complicated web of marine life influenced by an enormously wide range of living conditions. Evolution’s answers to the problems of living in such a demanding environment have provided us with a multitude of wonderful organisms of many colours, shapes and sizes. These unfamiliar life-forms are hidden just out of sight beneath the waves. The following pages bring just a few to the surface. The purpose of the Marine Nature Reserve is to conserve this wealth of wildlife. By promoting careful and responsible use of the Reserve, habitats and wildlife are protected from damage and disturbance. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 4 Habitats and water movement The coast is fringed by bays and promontories, cliffs and slopes, isolated rock pinnacles, caves and tunnels. Sea conditions range from tranquil to tempestuous. Huge storm waves pound the south and west coasts.Torrential tidal currents sweep through the Sounds and past headlands and offshore rocks. Sands and muds form the seabed in deep, sheltered water and in bays. Plants and animals live at different depths influenced by the amount of light reaching the seabed. Complicated as it is, this complexity produces diverse habitats and wildlife. If the water could be drained from Jack Sound, this would be the view from high above the sea outside Martin’s Haven. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 5 Wave action Strong currents Sheltered bay skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 6 Rocky shores The Reserve has 27 kilometres of coast. More than 95 percent is rocky shore. The shape of the shore and the animals and plants living there, vary according to the strength of the wind, waves, tides and currents they are exposed to. Steep, extremely exposed cliff are dominated by small, tough animals - few seaweed can survive. Wave-swept rock slopes provide a habitat for short, specialised forms of seaweed which hang on tightly to the rock surface. Partially sheltered rock platforms have rich communities with rockpools; seaweeds dominate the lower shore. Boulders on sheltered shores contain lush seaweed communities and provide shelter for many animals. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:38 Page 7 Splash zone lichens extend over sixty metres up cliffs. Shells protect these animals from drying out and being eaten. Limpets and winkles affect the appearance of shores by grazing on young seaweed. Shore-dwelling seaweed are specialists at conserving water during low tide. Vulnerable fish and soft- bodied animals survive on shores by living in rock pools and sheltering under boulders. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 8 Dense "forests" of large brown kelp plants are found only in the shallowest eight metres in the Reserve. The need for light restricts seaweeds to shallow water. Water clarity affects how much light is available. Kelps can extend down to 30 metres in very clear water, but only to about one metre in the more turbid water of nearby Milford Haven. Kelps are the largest marine seaweed. Their structure is simple. Their fronds form a forest "canopy", often encrusted by seafirs and seamats. Kelp stipes, the "tree trunks", are sometimes colonised by sponges and sea squirts. The holdfast anchors the plants to rock. Its root-like structure is an animal refuge. Over 250 species have been recorded living in kelp holdfasts. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 9 Many red seaweeds need less light than kelp. They thrive in the shade of the kelp canopy and form dense "meadows" down rock slopes below the edge of the forest. Blue-rayed limpets are tiny, but voracious and eat large holes in kelp stipes. Sea urchins are the "rabbits" of the marine world. They are the most important grazer of subtidal rock surfaces and are vital to maintenance of biodiversity. Flower-like anemones are actually predators equipped with stinging tentacles ready to capture food. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 10 The animal zone Light-dependant algae cannot survive in water much deeper than fifteen metres in the Reserve. Rocky surfaces deeper than this are smothered by characteristic "turfs" of animals fixed to the seabed . Tidal currents bring plentiful food, in the form of plankton and tiny organic fragments. These minute particles are filtered from the water by specialised seafirs, seasquirts, sponges and bryozoans, and trapped by the stinging tentacles of anemones and corals. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 11 Ross corals are not corals at all, but are colonies of countless individuals living in microscopic chalky building blocks. These fragile structures grow to over a metre across. Jewel anemones of many colour varieties form sheets of thousands of individuals. They reproduce by cloning, with parent anemones splitting into two. Delicate sponges, susceptible to damage, thrive in gentle water movement. In strong currents animals need to be firmly attached so as not to be swept away. In Jack Sound currents can reach over 10 miles per hour - about eight times faster than the average person can swim. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 12 Seabed sediments Sand, gravel and mud habitats often appear tranquil. They provide few places for animals to hide or find shelter and many which live there use camouflage or armour to survive on the sediment surface, or burrow beneath it. The anglerfish hiding in this picture has perfected the art of camouflage. It eats a wide variety of prey which it lures into a suitable position above its cavernous mouth by twitching a lure on the end of its dorsal fin. Scallops hide themselves under a thin layer of sediment and are protected by their thick shells from all but the most determined predators. Camouflage is achieved by body shape, colour and pattern. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 13 Eelgrass is the only subtidal British marine flowering plant, and is very rare in Wales. The plants form very productive beds which stabilise mobile sediment and provide shelter for fish. Burrowing animals get the best of two worlds. Their tentacles capture food from the water passing by, whilst their bodies remain safely protected. When danger threatens they completely retract into the sediment. skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 14 Predators and grazers hunt and forage These colourful fish live in and defend territories. Cuckoo wrasse are protogynous hermaphrodites. This scientific description simply means that they are all born females, but can become males when a dominant male disappears. This striking blue-marked one is male. Free floating plankton are paralysed by the stinging tentacles of jellyfish, passed to the mouth, then digested in the central stomach. Cuckoo wrasse - Labrus mixtus Tompot blennies live in cracks and crevices in rock. They have large, fringed tentacles, one above each eye. Tompot blenny - Parablennius gattorugine Starfish meander across the seabed using hundreds of tube feet with sucker-like ends, each species seeking out its own favourite prey. This seven-armed starfish eats Spiny starfish and common sea urchin brittlestars. Seven-armed starfish - Luidia ciliaris Marthasterias glacialis & Echinus esculentus skomer BOOKLET 1a:skomer BOOKLET 1a 30/9/08 23:39 Page 15 Grey seals are Britains largest predator. They roam widely hunting fish and shellfish. Each autumn they return to the same beaches and caves to have their pups and mate.

Load more