Oceanography-Chapter 7 Effects of Water Movement on Marine Life PDF

Effects of water movements on marine life The reason wind moves clockwise in the North and not the other way has to do with the heating of air at the equator and air’s tendency to move towards low-pressure systems. Winds push the surface of the ocean’s water and are a major force in creating ocean c...

Effects of water movements on marine life The reason wind moves clockwise in the North and not the other way has to do with the heating of air at the equator and air’s tendency to move towards low-pressure systems. Winds push the surface of the ocean’s water and are a major force in creating ocean currents. Ocean currents thus tend to reflect the wind patterns above them. The heat from the Sun is what generates wind. Wind is created by the movement of heated masses of air in conjunction to cooling masses of air. Air heated by the sun becomes less dense and rises, creating an area of low pressure. The air from adjacent areas moves toward the low pressure, and that movement is wind. The air on land heats up faster than in the sea and that is why the wind blows in from the sea, but only during the day. At night, because land air cools off much faster than the sea, the wind will then blow out from the shore towards the sea. Effects of Global Warming Major effects are that the "bands" of life appear to be moving polewards, ie tropical species are being found further and further north/south. coral bleaching is apparently a major problem (all the algae in corals being ejected as the coral has come under stress, in this case thermal stress.) some specific species are suffering losses due to their inability to thermo-regulate well enough to keep up with the changes that global warming is producing. If major ocean currents change then this may shift the distribution of food resources in the oceans, destroying some habitats, but also creating others. Ocean currents recycle our planet by maintaining the ocean water at a stable low temperature and by distributing food to all the ocean's inhabitants and also to the land inhabitants throughout all the continents. The circulation of these major ocean currents influence global climate and benefit all living species by providing a transportation system. Ocean currents naturally transport plankton, fish, heat, and different types of chemicals like salt, oxygen, and carbon dioxide. Many marine animals rely on currents for the dispersion and upwelling of nutrients, both of which would be very different without the Coriolis effect. “Marine biota > plankton” these organisms tend to float with the oceans' currents. Many organisms depend on currents for dispersal in the larval stage. The Coriolis effect also influences upwelling, the bringing up of nutrient-rich cold waters to the surface. Many organisms rely on upwelling for nutrition. The Coriolis effect moves the very environment of marine organisms and thus shapes their lives in a profound way. Upwelling: This natural phenomenon occurs when the wind blows from land out to sea and also along the shore. The wind pushes the coastal surface water further out to the sea and the deeper water moves in to replace the missing surface water. Upwelling can change the temperature of both the surface ocean water and the adjacent land mass in a dramatic fashion, as well as increasing biological productivity of the ocean. Downwelling: When surface waters are influenced by wind and the Coriolis effect they are driven toward the coastline where it piles up. The driven water is forced against the shore where it cannot go back horizontally, so it is forced. This vertical flow of water to a deeper level is called Downwelling. This process carries oxygen to deeper levels in the ocean system, replenishing its supply to oxygen dependent organisms. Effects of tides and moon phases on migration, spawning and feeding UPWELLING CURRENT NE MONSOON UPWELLING CURRENT SW MONSOON SURFACE CURRENT NE MONSOON SURFACE CURRENT SW MONSOON NE MONSOON SW MONSOON Intertidal zones, those areas close to shore, are constantly being exposed and covered by the ocean's tides. A huge array of life lives within this zone. Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence. It can be underwater anywhere from daily to very infrequently. Many species here are scavengers, living off of sea life that is washed up on the shore. Many land animals also make much use of the shore and intertidal habitats. A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion. Tide pools with sea stars and sea anemone Tides have different effects all over the Earth. In rocky intertidal zones, the tide pools can be affected greatly with the change in these tides. The temperature and salinity in the tide pools can increase and decrease quickly. As the water warms and evaporates the salinity level of the water goes up. There can also be an increase in the UV light when the organisms are out of water. All of these effects cause the organisms to adapt or die. Most of the effects of the tides on organisms living in these areas are due to the exposure to air. Another main problem is dehydration. Some strategies for survival in this area are to move to a moist area in order to maintain water. Also to move to a sheltered area protected from the sun and the crashing of the waves. Mudskippers are members of the subfamily Oxudercinae (tribe Periophthalmini), within the family Gobiidae (Gobies) The bivalves "clam up" in order to keep themselves from drying out. Limpets use their home scars to hide in sometimes trapped for life. The snails use their operculum like a tiny door to close themselves up inside. Limpets Some organisms cover their body with a protective layer. The sea anemones secrete a mucus to help them keep moist. Some also attach shell fragments to themselves. Worms like the polychaete worm and sand castle worm live in tubes. Organisms that have light colored shells don't absorb the heat as fast but rather reflect it. Having ridges on the shells also keep the organisms cooler as the texture of having a ridged shell helps reflect most light and sun rays. Organisms that live in the pounding surf have found ways to adapt too. Algae use their holdfast to attach to the rocks and keep it in place. It's stem is flexible and moves with the wave motion. Mussels attach by their byssal threads and the members of gastropods use their foot to secure them in place. The clingfish uses a modified fin, on its pelvic area, like a suction cup. Having a compact size and a hydrodynamic shape can also help to hold colonies of organisms like barnacles and chitons in place. Changes in food availability can be a major problem. Barnacles out of water can not feed since they are filter feeders and need the water to obtain their food. There is a competition for space in these tide pools as organisms fight for shady areas. Larval settlement is an effect of the tides. These larvae need a place to attach to begin their advancement to adulthood. All of these effects vary according to the duration of exposure, the time of day during the exposure and the season during exposure. Probably the greatest effects of tides on sea life are on the creatures that are dependent on tide pools and beaches like star fish, clams, mussels, oysters, even sea weeds. Mammals that come ashore like sea lions and seals are also effected. At the edge of the sea - called the intertidal zone - tides affect marine life because tides are a form of kinetic energy. Tides (and waves) bring water and food to animals that live in the intertidal zone, and tides take away wastes. The organisms just sit there and the ocean does the work. Outside the intertidal zone, tides have less effect, except of course they create currents and cause mixing. The phenomena of the abundance of life in action on edges is called the EDGE EFFECT At low tide, places become dry with puddles ,where fish have laid eggs ,crabs and all sort of edge creatures move around, and there are many birds and bird droppings At high tide ,this place is now covered with water and fish are swimming into this space which is now rich with the garbage the low tide visitors left behind There is much life both plants and all the other fish, birds, crabs, bugs etc that moves with the movement of the tide over the changing bottom which is wet for a time and then dry with the sun or moon added. Both having big effect on the life that lays below The microscopic world here is more intense than any where else in the world This is the edge and edges are the most abundant places for life. Water and land edges are the richest as opposed to forest and prairie edges, and the sea edge is the richest of all because of the tides The effects are not just on the water or ground, they carry on into the air, from the land side a current goes straight up into the air ,and on the water side it falls down, this aerial elevator moves with the tides and you can see birds rising using this current, or falling quickly to catch a morsel or just riding it flapping their wings to stay in the same place Most of the fish and aquatic life on the coast are on this moving edge and, most of the life on the land is as well Without tides, dunes cannot form tides expose sea sand to the wind, which blows it into dunes. tides create an area of rocky shore where specialised organisms have evolved. Tides thus increase the biodiversity of the coast (limpets, barnacles, oysters, etc.) tides create large areas for specialised organisms within harbours and embayments (sand and mud flats, mangroves, etc.). such areas may act as nurseries for various marine species. tides create currents that mix the water so that surface plankton is spread and bottom nutrients re-surface. This makes plankton available throughout the year. tides create currents that transport plankton to sessile filter feeders such as clams, sponges, seasquirts, etc. It creates very rich habitats where currents pass. tides create currents that transport and mix coastal sediments. Without them, the coast would be more sensitive to sewage disposal and runoff from the land. It would support fewer people. Sea squirts