AQUATIC ALGAE BLOOM NOTES:
FINAL EXAM NOTES FOR BIOLOGY WRITTEN BY JASON R. LIZAMA
What is an algae bloom?
When these excess nutrients enter water bodies, they serve as fertilizer for algae, leading
to rapid growth, known as algal blooms. These blooms can cover large water areas,
especially in coastal zones such as the Gulf of Mexico, where the nutrient influx is often
high due to runoff from the Mississippi River.
What is nutrient pollution?
Nutrients like nitrogen and phosphorus, essential to plant growth, are a natural part of
underwater ecosystems. But when they run off urban and rural surfaces and flow into a
river, lake, pond, or reservoir in excess a phenomenon known as nutrient pollution
they act like fertilizer and promote the growth of algae and bacteria. Most excess
nutrients enter waterways via agricultural runoff (particularly from animal manure and
chemical fertilizers that get washed from farms by rain), leaked waste from animal
feedlots, stormwater runoff from urban and suburban areas, and discharges from
wastewater treatment facilities.
What is Hypoxia DUMBED DOWN?
Hypoxia is when there is not enough oxygen in the water for most animals and plants to
survive. It happens when the oxygen levels drop very low, usually because of things like
algae overgrowth, which uses up the oxygen. In places like the Gulf of Mexico, this lack of
oxygen can create "dead zones" where fish, shrimp, and other marine life can't live.
What is happening to the Gulf’s ecosystem?
Decomposition of Algae:
As algae die, they sink to the bottom of the water body, where bacteria and other
decomposers break them down. This process of decomposition consumes oxygen, as
bacteria use oxygen to break down the organic material. In the process, large amounts of
oxygen are depleted from the water, leading to hypoxic conditions.
Stratification and Limited Mixing:
Many aquatic environments, including the Gulf of Mexico, experience stratification,
where the water becomes layered with warmer, lighter water on top and cooler, denser
water below. This limits the mixing of oxygen-rich surface water with deeper waters. As a
result, the oxygen in deeper waters is depleted faster than it can be replenished,
contributing to the formation of dead zones.
Consequences of what’s happening?
Decline in Marine Life: Dead zones are characterized by extremely low levels of
dissolved oxygen, making it difficult for most marine organisms, including fish, crabs,
and shellfish, to survive. Species that rely on oxygen for respiration may be forced to
migrate or die in these areas, leading to a significant reduction in biodiversity. The lack
of oxygen affects every level of the food chain, from plankton to larger fish species.
Disruption of Ecosystems: The loss of oxygen and the collapse of local marine life
have ripple effects throughout the ecosystem. As certain species die off or migrate,
predators and other animals that rely on them for food also suffer. In addition, the
decomposing algae further exacerbates nutrient pollution, as the bacteria responsible for
decomposition release more nitrogen and phosphorus back into the water, perpetuating
the cycle of eutrophication.
Economic Impacts: The formation of dead zones can have severe economic
consequences, especially for industries dependent on marine life. Commercial and
recreational fishing industries are directly impacted, as fish populations decline in
hypoxic areas. Tourism in coastal areas may also suffer due to the loss of marine
biodiversity and the aesthetic degradation of the water.
Long-Term Environmental Damage: While dead zones can fluctuate in size and
intensity from year to year if nutrient pollution is not reduced, these zones can persist
and even expand. Over time, they can lead to long-term environmental degradation,
including shifts in species composition, reduced habitat quality, and the decline of
important marine ecosystems such as coral reefs and marshes.
NATURAL SELECTION NOTES
FINAL EXAM NOTES FOR BIOLOGY WRITTEN BY JASON R. LIZAMA
How do I summarize the question answer?
A species that has evolved through natural selection for hundreds of thousands of years
might be poorly adapted to current environmental conditions if those conditions change
too quickly or in ways that the species cannot adapt to in a short time. Natural selection
works gradually, favoring traits that help a species survive in its environment. However,
if the environment changes too rapidly. For example: due to climate change, pollution,
habitat destruction, or new diseases, the species might not have enough time to evolve
the necessary adaptations. In such cases, the once helpful traits may no longer be
suitable, leaving the species struggling to survive under new conditions.
For example, animals that have evolved to live in cold environments might not survive as
temperatures rise, or plants that rely on certain pollinators might face difficulties if those
pollinators disappear. Evolution takes time, and sudden environmental changes can
outpace a species’ ability to adapt, leading to poor survival or even extinction.
What is the more complicated answer?
Rapid Environmental Change: If environmental conditions change too quickly
(climate change, habitat destruction, or pollution), the species may not have enough time
for evolutionary processes to occur. Evolution works gradually, and significant changes
in the environment can outpace the species' ability to adapt.
Genetic Drift: In small populations, random changes in allele frequencies (genetic
drift) can cause the loss of beneficial traits, making the species less suited to current
conditions, even though those traits may have been advantageous in the past.
Loss of Genetic Variation: If a species experiences a bottleneck or a founder effect
(reduced genetic diversity due to small population size), the genetic variation necessary
for adaptation to new environmental stresses may be limited. Without sufficient genetic
variation, the species may lack the traits needed to survive in changing conditions.
The mismatch between Traits and New Environment: Traits that were once
advantageous in a previous environment may become detrimental under new conditions.
For example, a species adapted to cooler temperatures may suffer as global warming
increases temperatures, or species adapted to a stable ecosystem might struggle when
new species invade, causing competition for resources.
Inability to Adapt to New Selective Pressures: If new selective pressures (such as
new predators, diseases, or changes in food availability) emerge faster than the species
can evolve new traits, the species might not be able to cope with the challenges, leading
to a decline in population or extinction.
Co-evolutionary Changes: Species often evolve in response to other species (e.g.,
predator-prey or host-parasite relationships). If the co-evolutionary dynamics change.
For instance, if a predator evolves to be more efficient at hunting the prey species may
struggle to adapt, especially if it hasn't evolved new defense mechanisms in time.
Disruption of Ecological Niche: A species may be well-adapted to a specific
ecological niche (a role in the ecosystem), but if this niche is disrupted by human activity
(deforestation & pollution), the species may no longer have the appropriate resources or
conditions to thrive.