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Aquatic Adventures
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aquatic
An aquatic ecosystem is an ecosystem located in water bodies. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Marine ecosystems cover approximately 71% of the Earth's surface and contain approximately 97% of the planet's water. They generate 32% of the world's net primary production. They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, in the water. Approximately 85% of the dissolved materials in seawater are sodium and chlorine. Seawater has an average salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into the following zones: oceanic (the relatively shallow part of the ocean that lies over the continental shelf); profundal (bottom or deep water); benthic (bottom substrates); intertidal (the area between high and low tides); estuaries; salt marshes; coral reefs; and hydrothermal vents (where chemosynthetic sulfur bacteria form the food base). Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, and sharks. Fish caught in marine ecosystems are the biggest source of commercial foods obtained from wild populations. Environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources (for example overfishing of certain species), water pollution, and building on coastal areas.
水生動物
水の生態系は、水体に位置する生態系です。互いの上で、そして、彼らの環境に関して依存している有機体のコミュニティは、水の生態系に住んでいます。水の生態系の2つの主要なタイプは、海の生態系と淡水の生態系です。海の生態系は地球の表面のおよそ71%をおおって、惑星の水のおよそ97%を含みます。彼らは、世界の正味の一次生産の32%を生み出します。彼らは、水の中で溶かされた合成物（特に塩類）の存在によって、淡水の生態系を区別されます。海水の中の溶かされた材料のおよそ85%は、ナトリウムと塩素です。海水は、水の千につき35部（ppt）の平均塩分を持ちます。実際の塩分は、異なる海の生態系の間で異なります。海の生態系は、以下の地帯に分けられることができます：大洋の（大陸棚の上にある海の比較的浅い一部）;profundal（一番下であるか深い水）;benthic（一番下のサブストレート）;満潮と干潮の間の（上下の流れの間の地域）;河口;塩生沼沢;珊瑚礁;そして、熱水噴出孔（化学合成硫黄細菌が食物主成分を形成する所で）。海の生態系で見つかる有機体の種類は、褐藻、渦鞭毛虫、珊瑚、頭足類、棘皮動物とサメを含みます。海の生態系に引っかかる魚は、野生の住民から得られる商業的な食品で最も大きい源です。海の生態系に関する環境問題は、沿岸地域で海洋資源（たとえば特定の種の乱獲）、水質汚染と建築の支えられない搾取を含みます。
Scuba
Scuba diving is swimming underwater, or taking part in another activity, while using a scuba set. By carrying a source of breathing gas (usually compressed air), the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in snorkeling and free-diving, and is not hindered by air lines to a remote air source. The scuba diver typically swims underwater by using fins attached to the feet. However, some divers also move around with the assistance of a DPV (diver propulsion vehicle), commonly called a "scooter", or by using surface-tethered devices called sleds pulled by a boat. For the history of diving, see timeline of underwater technology. Scuba today typically refers to the in-line open-circuit equipment, developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water. However, rebreathers (both semi-closed circuit and closed circuit) are also self-contained systems (as opposed to surface-supplied systems) and are therefore classified as scuba. The term SCUBA (an acronym for Self Contained Underwater Breathing Apparatus) arose during World War II, and originally referred to United States combat frogmen's oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare. Although the word SCUBA started as an acronym, it is now usually seen as a normal word, "scuba". It has become acceptable to refer to "scuba equipment" or "scuba apparatus" ? examples of the linguistic RAS syndrome. Scuba diving is still evolving, but general classifications have grown to describe various diving activities. These classifications include: Commercial diving Military diving Naval diving Police diving Professional diving Recreational diving Rescue and recovery diving Scientific diving Technical diving Cave diving Cavern diving Deep diving Ice diving Wreck diving
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