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Conservation and Biodiversity - Vocabulary Flashcards

Global biodiversity crisis

  • Extinction projections by end of the 21st century are highly debated; the transcript notes a large projected loss but does not specify the exact percentage.
  • Key takeaway: rapid biodiversity loss is a major concern tied to human activities.

Marine biodiversity and fisheries

  • About 3 imes10^9 people rely on fish as a major protein source.
  • Fisheries and aquaculture support livelihoods for about 10 ext{-}12 ext{ %} of the world population.
  • 60 ext{ %} of people live within 100 km of the coast.
  • Marine vertebrate populations declined by 49 ext{ %} between 1970 and 2012.
  • Fish species used by humans have declined by about 50 ext{ %}; some species declined more.
  • Roughly 1/4 of shark, ray, and skate species are threatened due to overfishing.
  • Tropical reefs have lost >50% of reef-building corals in ~30 years.
  • Global mangrove cover decreased by about 20 ext{ %} between 1980 and 2005.
  • Marine fisheries are overfished at about 29 ext{ %}.
  • If temperature rise continues at current rates, oceans may be too warm for corals by 2050.
  • Seabed mining licenses cover about 1.2 imes 10^6{
    m ext{ km}^2} of ocean floor.
  • Over 5 imes 10^{12} plastic pieces are in the sea ( >250,000 tonnes).
  • Oxygen-depleted dead zones are increasing due to nutrient runoff.
  • The ocean provides at least 2.5 imes 10^{12}} USD/year in economic benefits.
  • Only 3.4 ext{ %} of the ocean is protected; much of this protection is not effectively managed.
  • Increasing marine protected area coverage to 30 ext{ %} could generate up to about 9.2 imes 10^{11} USD between 2015 and 2050.

Extinctions: mass vs background

  • Two main categories:
    • Mass extinction: a large proportion of species go extinct in a short time due to rapid environmental change.
    • Background extinction: extinction occurs at lower rates between mass-extinction events.
  • The current global rate of species loss is often described as being about 1000\times higher than the background rate.

Why mass extinction now?

  • Human activities release greenhouse gases that trap heat in the atmosphere, leading to climate change and additional stress on biodiversity.
  • The resulting rapid environmental change is a key factor driving the current biodiversity crisis.

Conservation biology (definition)

  • A multidisciplinary science focused on preserving Earth's natural resources and protecting biodiversity.

What is biodiversity?

  • Biodiversity comprises:
    • Ecosystem diversity: number of ecosystems in a region.
    • Species diversity: number of species in an ecosystem.
    • Genetic diversity: number of alleles in a species.
  • It includes genetic variability, the variety of species, and the variety of ecosystems.

Biodiversity hotspots

  • There are about 25 biodiversity hotspots worldwide.
  • They cover <1% of the world's area but contain ≥20% of the world’s species.
  • Examples listed:
    • Tropical rain forests: Costa Rica
    • Coral reefs: Philippines
    • Islands: Madagascar

Where is most biodiversity?

  • Biodiversity generally increases toward the equator; moving toward the poles, biodiversity declines.
  • Example metric: marine copepod species number decreases with latitude away from the equator.

Factors influencing biodiversity

1) Solar energy available

  • More solar energy supports greater species richness.
    2) Evolutionary history of an area
  • Longer time without climatic disruption (e.g., ice ages) yields greater diversity.
    3) Rate of disturbance
  • Intermediate disturbance often yields the greatest species richness (neither too calm nor too harsh).

Succession and ecosystem change

  • Succession: change in species composition over time after a disturbance.
  • Stages:
    • Colonizing (pioneer) community: first arrivals, good dispersers, poor competitors.
    • Intermediate communities: mix of colonizers and competitors.
    • Climax community: larger, well-adapted species dominate.
  • Primary succession: starts with barren soil; examples include mosses and eventual trees.
  • Secondary succession: starts after disturbance leaves soil; faster due to a head start.
  • Disturbance is a normal, recurrent driver of succession.

Ecological succession after Mt. St. Helens

  • Documented recovery over years; biodiversity returns as soil and seeds re-establish.

Disturbance and diversity over time

  • Biomass can increase while diversity changes; peak species richness often occurs after an intermediate level of disturbance.

Human disruptions to ecosystems

  • Major pathways:
    • Introduced species
    • Overexploitation
    • Deforestation
    • Habitat fragmentation
    • Climate change
  • Examples: Kudzu, Nile perch, Zebra mussels

Overexploitation

  • Overexploitation is a key driver of recent biodiversity loss and species extinctions.
  • Includes unsustainable hunting/fishing, wildlife trade, and exploitation for souvenirs.

Deforestation and habitat fragmentation

  • Deforestation in the tropics is a leading cause of biodiversity loss.
  • Fragmentation further reduces habitat quality and species persistence.

The fossil-fuel era and acid rain

  • Burning fossil fuels releases sulfur dioxide (SO$2$) and nitrogen dioxide (NO$2$).
  • In the atmosphere, these form sulfuric acid (H$2$SO$4$) and nitric acid (HNO$_3$), leading to acid rain.
  • Acid rain damages leaves, reduces photosynthesis, and can kill trees.
  • Acid rain distribution increases acidity (lower pH) in rain across affected areas.
  • Displayed data show decreasing sulfate deposition in some regions over time, but historical acidity remains a concern.

Climate change: greenhouse gases and temperatures

  • Atmospheric CO$_2$ has risen since the Industrial Revolution; recent readings near 400\text{ ppm} (and higher in recent years).
  • Correlation vs causation debates exist, but broad consensus links greenhouse gas rise to warming.
  • Even small increases in global temperature (e.g., 1^{\circ}\text{C}) can have ecological consequences.

Sea-level rise and Arctic melt

  • Projections indicate substantial coastal impacts and urban exposure to sea-level rise by the end of the century.
  • Arctic glaciers are melting, contributing to rising sea levels.

Chemicals and contaminants: biomagnification

  • Pollutants concentrate up the food chain (biomagnification).
  • Example: DDT concentration increases dramatically from water to small fish to large fish to birds.
  • Top predators exhibit the highest tissue concentrations (e.g., birds of prey).
  • Mercury in fish can accumulate with notable levels in large predatory fish (illustrative data shown).

Pesticides and human exposure

  • Pesticides (e.g., Atrazine) have ecological and human health considerations; include public awareness and policy discussions.

Relative risks to human welfare (high-level)

  • High-risk problems: habitat alteration/destruction; species extinction and loss of biodiversity; stratospheric ozone depletion; global climate change.
  • Medium-risk problems: herbicides/pesticides; toxins in surface waters; acid deposition; airborne toxins.
  • Low-risk problems: some pollutants and management issues (as listed in the table).

What can I do? (actionable steps)

  • Drive a smaller, fuel-efficient car; improve energy policies; adjust thermostat conservatively; recycle; reduce fertilizer and pesticide use; use eco-friendly mowing.
  • Use energy-efficient lighting and appliances; compost organics; support environmentally conscious policies.
  • Walk or bike; carpool; use public transit; manage electricity with power strips; insulate homes; choose energy-efficient devices.
  • Read about legislation and advocate for sustainable practices.