Ocean Systems: human dependence and modification

Ocean Systems: human dependence and modification 2 Major Systems: How do ocean currents affect humans? trade routes and weather How do we depend on Ocean food webs? our food – also other creatures depend on the sea for food/reproduction -A few questions to lead them into the next slide: -How do ocean currents affect humans? (historically it determined trade routes; also affects weather) -How do we depend on Ocean food webs? (our food – also other creatures depend on the sea for food/reproduction – think bears eating salmon)

Ocean Systems: human dependence and modification We depend on the ocean for: Weather: The oceans absorb lots of energy from the sun. Warmer water = more evaporation & more rain Cooler water = less evaporation & less rain Food: 1/6 of the worlds population relies on the ocean as their primary source of protein. Transportation: most of the worlds large bulk goods are transported by ship Recreation: Many countries main source of income is through tourism fueled by the ocean. Beach resorts, sport fishing, boating, scuba diving, etc. etc. -Weather: -The oceans absorb lots of energy from the sun. -Warmer water = more evaporation = more rain in a general area; cooler water = less evaporation = less rain in a general area -this also meshes with El Nino/La Nina - both of these climate events occur when trade winds change causing warm/cold water concentrations to change places on the earth which, in turn, affect global weather patterns. -Food: -1/6 of the worlds population relies on the ocean as their primary source of protien. -Transportation: -most of the worlds large bulk goods are transported by ship -Recreation: -Many countries main source of income is through tourism fueled by the ocean. Beach resorts, sport fishing, boating, scuba diving, etc.

Modification by Humans Overfishing: What could have if humans took out most of the tuna in the food web? the marlins now have lost one of their main food sources and the squid have lost a main predator Overfishing of shrimp also takes away a main food source for the tuna -Trace the effects of basically eliminating certain parts of the food web. -For example: lets say humans take out most of the tuna in the web – the marlins now have lost one of their main food sources and the squid have lost a main predator. Overfishing of shrimp also takes away a main food source for the tuna, etc. -One thing to consider is that the ocean is constantly in flux. If a species runs out of a food source it may migrate to another area and begin disrupting another marine environment. Some species, however, are limited to a certain range of temperatures water wise, meaning if these creatures lose a food source they may go extinct if they cannot adapt to a different temperature range. -One thing you can extend here are the possible effects of global warming on the food chain. If the water begins to warm overall, creatures must migrate with their temperature range in order to survive. Remember, temperature range that matters in an environment is within 1 or 2 degrees. A 2 degree temperature difference makes a ton of difference in an ecosystem. Imagine water and ice. The difference between 0 degrees Celsius and 2 degrees Celsius is the difference between staying frozen and melting.

Ocean Systems: human dependence and modification Artificial Reefs - human-made underwater structure, typically built for the purpose of promoting marine life Artificial reefs are basically a great idea that have a horrible history implementation-wise. For example: in the 1970’s thousands of old car tires were dumped off the coast of Ft. Lauderdale, Florida in order to form an artificial reef. The tires then began to drift away, damaging nearby natural reefs. More recent efforts have had more success, but the main problem is it takes time to form a new reef system. It may be decades before we know if artificial reefs created in the past 10 years are a success. Recent artificial reefs include old warships (stripped of any rubber/plastic or possibly toxic materials) and old subway cars. The video takes about 10 minutes and shows the sinking of the Texas Clipper off Padre Island to form a reef. It also show the marine life that have moved into the ship to create the reef. The ship was sunk on November 17, 2008. Learn more about artificial reefs with this video

Run Off and Pollution: Excess Nitrogen or Phosphorus from agriculture or factory waste gets dumped into rivers/streams. Eventually all this excess stuff gets dumped into the ocean. Harmful Algal Blooms (HABs) can possibly result from the excess Nitrogen/Phosphorus being dumped into the oceans. Can also be called “Red Tide” because of the brown/reddish color of the water at the surface. HABs can kill numerous fish and cause harm to humans who eat said fish. Basically when excess nitrogen or phosphorus gets dumped into rivers/streams it is a bad thing. Excess fertilizer in crops/agriculture can lead to this as can factory waste. Eventually all this excess stuff gets dumped into the ocean. Phosphorus and nitrogen happen to be the main food source of many types of algae. HABs (Harmful algal blooms) possibly result from this excess phosphorus/nitrogen being dumped into the ocean. Some HABs occur seasonally and naturally, while others appear to be linked to runoff/pollution. HABs can also be referred to as “Red Tide” for the brown/reddish color that the water takes on when these creatures are rapidly reproducing/feeding on the surface. HABs can kill numerous fish and cause harm to humans who eat said fish.