Ocean Systems: Human Dependence and Modification

Human Dependence and Modification 2 Major Systems in the ocean: Ocean currents Ocean food webs -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)

Human Dependence We depend on the ocean for: Weather The oceans absorb a lot of energy from the sun. The oceans regulate the temperature of the planet. Water heats and cools more slowly than land effecting the local temperatures. -Weather: -The oceans absorb lots of energy from the sun. -regulates global temperatures (cooler) - students have not been exposed to effect of oceans on weather so this is new to them. -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.

Human Dependence We depend on the ocean for: Food Transportation Seafood provides a lot of world’s protein. Transportation most of the worlds goods are transported by ship Recreation Many countries main source of income is through ocean tourism -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.

Human Dependence 5. Oxygen Blue green algae provides 70-80% of oxygen to our atmosphere This is a common misconception that all of our oxygen comes from trees – where 70-80% actually comes from the blue-green algae in the oceans. So if we trash our oceans – it has a greater effect !!!!

Human Modification Over-fishing Called Harvesting Disrupts the food web May cause organisms to migrate to other areas -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.

Human Modification 2. Artificial Reefs human-made underwater structure, typically built for the purpose of : Stopping erosion Promoting marine life Restoring damaged reefs Increases tourism Fishing/scuba-diving 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. What students get confused about is that old ships are not placed in the ocean to preserve them - 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. Texas Clipper – (9 min)

Human Modification Run Off and Pollution Excess phosphorous and nitrogen fertilizer can cause pollution in the ocean as can factory waste. These harmful algal blooms are called “red tides” because of the color it produces Basically when you fertilize the land the fertilizer runs off and “fertilizes” the algae in the water. The algae grows until there is too much and some dies – the increase of dead algae brings more bacteria to the water – and the bacteria use up the oxygen in the water leaving not enough for the fish. 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.

Discuss with your neighbor… What are some other ways you can think of that humans effect the ocean? In what ways are humans positively impacting the oceans? Possible responses- oil spills, trash and plastic in the ocean – climate/temperature change Creation of artifical reefs is positive – trying to not use plastic bags and water bottles (new laws in cities)