8.2 Human Impacts on Ecosystems

stress

causes impaired function, decreased individual growth, or reduced reproduction, and in extreme situations, organisms could die

zone of tolerance

describes how different abiotic factors may impact the ability of an organism to live in an ecosystem. can vary from sunlight to the amount of pollutant in the water

indicator species

will be the first to disappear from an ecosystem under stress

measures the health

* dissolved oxygen
* nutrient levels
* presence of specific disease-causing organisms or toxins

dissolved oxygen

the amount of oxygen that is in the water and available to organisms to carry out aerobic respirations. Cooler waters have a higher capacity to hold dissolved gasses, such as DO, than warmer waters

moving water

DO is added to aquatic ecosystems via _____ interacting directly with the air and the oxygen from photosynthetic organisms in the ecosystem

consuming

DO is removed from aquatic ecosystems by organisms ____ it during aerobic respiration

good water quality

* BOD decreases
* DO increase
* Temp decrease

bad water quality

* BOD increases
* DO decreases
* Temp increases

biological oxygen demand

measuring this of an aquatic ecosystems can determine how much DO of all the organisms in the system need to survive and thrive

hypoxic

when BOD exceeds DO in the systems, oxygen deficit

increase

BOD can ____ if there is a large amount of organic waste that will be decomposed by microbes using aerobic respiration

anoxic

there is no DO in a body of water

deep water horizon

April 20, 2010, in the Gulf of Mexico, a drilling rig experienced catastrophic failure, resulting in the largest oil spill on record. Over 210 million gallons of oil flowed from the ground into the ocean before the mine could be sealed in September.

The massive amount of oil created an enormous environmental disaster, killing wildlife, impacting fisheries and tourism. To clean up the oil, millions of gallons of chemical dispersants 🧼were put into the water, as well as the use of controlled burns.  As we learned when studying air pollution, **🔥** burning these fuels releases massive amounts of atmospheric carbon. 

exxon valdez oil spill

The collision spilled 10.8 million gallons of oil into the Prince William Sound. This spill is considered the largest US oil 🛢️ spill in history. The oil spread almost 500 miles off of the spill site to go on to stain thousands of miles of coastline 🏖️

The spill also greatly reduced the biodiversity 🐧 🦅 🐟 🦐 of the Sound. More than one hundred thousand (100k +) birds, fish, seals, otters, and other animals would perish as a result of the oil in the water 😭

Besides ecological effects, oil spills 🛢️ can have economic consequences where people are less inclined to visit the coastline and beaches 🏝️ because they are stained in oil. That means that Prince William Sound tourism money 💸 will fly away 👋

coral reef benefits

1. biodiversity/habitat
2. shore protection
3. tourism
4. food source
5. medicines

physical threat

* boat damage. anchors, chains, snorkelers and divers
* blast fishing
* cyanide poisoning

chemical threats

* sedimentation
* oil spills
* plastic waste and microplastics
* rising sea temps - bleaching
* toxins (sunscreens, pesticides, metals)

biological threats

* invasive predators (lionfish, crown of thorns starfish
* pathogens (black band disease)

storm impacts

climate change - bigger, more frequenct hurricanes

temperature changes

climate change - currents changing

salinity changes

climate change - melting ice

predation

invasives - aquarium pets and boat ballast

algal overgrowth

sedimentation from development, eutrophication (nutrients)

oils spills impact wildlife

* oil that floats on surface of water coats the feathers of birds, robbing them of both insulation and the ability to fly
* fur of marine mammals like seals and sea otters can become saturated with oil, inhibiting their waterproofing and ability to maintain their body temp
* can injest hydrocarbons while grooming, die from poisoning

producers and consumers are impacted

* sediment suspended in the water can affect primary producers (plants) because light infiltration is reduced. impacts plants ability to photosynthesize and add oxygen to the water
* predators that use vision as their primary sense for hunting are also impacted
* as sediment settles, can disrupt the eggs and larvae of aquatic species like fish, insects, and mollusks

heavy metals found in drinking water

* lead
* arsenic
* cadmium
* mercury
* copper
* chromium
* causes cancer, organ damage, and neurological issues

mercury poisoning

most often causes by eating fish or other aquatic organisms

* causes brain damage and birth defects