APES 8.2 (Human Impacts on Ecosystems)

Range of Tolerance

Organisms have ROT for abiotic conditions in their habitat; they also have ROT for human activity pollutants

ROT Categories

pH, temperature, salinity, sunlight, nutrient levels (ammonia, phosphate)

Effects of Pollutants

Limited growth, and reproductive function

Difficulty breathing, potential asphyxiation (suffocation)

Hormonal disruption

Death (if the concentration of pollutant is high enough)

pH Tolerance

As pH decreases (more acidic) outside the optimal range for a species, pop. declines

What happens when pH leaves ROT

Organisms cannot survive at all, due to Aluminum toxicity and Disrupted blood osmolarity (Na⁺/Cl^- balance disrupted at low pH)

Purpose of Indicator Species

Can be surveyed and used to determine conditions of an ecosystem (soil, water, etc.) 

Examples of Indicator Species

High whitemoss/filamentous algae pop. indicates pH < 6.0

High crustacean pop. indicates pH > 6.0

Zooxanthellae

Mutualistic relationship between coral & photosynthetic algae

What does a Coral Reef mean?

Zooxanthellae and algae supply sugar & coral supply CO₂ + detritus (nutrient containing org. matter)

Temperature Tolerance of Algae

Narrow Temperature Tolerance and leaves when temperature rises

What do Pollutants from runoff do to Algae?

Forces Algae from reefs

Human Disruptions on Coral Reefs

Humans disrupt coral reef ecosystems via greenhouse gas emissions (warming ocean temp. & bleaching coral

Effects of Overfishing and bottom trawling in Coral Reefs

Decreases fish populations in coral reef ecosystems and can break reef structure and stir up sediment

Sediment (sand, silt, gravel) runoff pollution effects

Eutrophication; too much can make the water more turbid, causing the sun to warm the water and go over the ROT; lack of sunlight for producers due to lack of photosynthesis

Toxicants

Chemicals, synthesized by humans that have a detrimental effect on the environment

Effects of Toxicants

Kill fish, algae, etc. 

Examples of Toxicants

Chemicals in sunscreen, oil from roadways, pesticides from ag. runoff

Nutrients

Ammonia from animal waste and Nitrate/Phosphates from agricultural or lawn fertilizers

Hydrocarbons in crude oil effects

Toxic to many marine organisms and can kill them, especially if they ingest (eat) the oil or absorb through gills/skin

Physiological effects of oil spills

Decreased visibility

Decreased photosynthesis

Oil sticking to bird feathers

Oil sinking to the bottom and killing bottom-dwellers due to direct toxicity and suffocation

What happens if oil washes ashore?

Decrease tourism revenue and kill fish, decreasing fishing industry revenue, hurt restaurants that serve fish

Where else can oil settle?

Deep in root structures of estuary habitats like mangroves or salt marshes

Effects of oil in mangroves or salt marshes

Toxic to salt marsh grasses, killing them and loosening their root structure, leading to coastline erosion

Can remove habitats used by fish and shellfish for breeding ground

Oil Spill Cause

Occurs when an underwater oil well explodes/blows out or when a tanker runs into a rock/iceberg and is punctured

Methods to cleanup oil spills

Burning/Booms

Dispersion

Skimming

Absorption