Ecosystems of Earth

• Earth's ecosystems exhibit incredible variety with unique challenges.
• Ecosystems face threats such as pollution, invasive species, and climate change.
• Earth's major ecosystems respond to environmental threats and changes.

Ecosystem Definition

• An ecosystem constitutes a community of interacting living organisms and their physical environment.
• Ecosystems include both biotic (living) and abiotic (non-living) components functioning as a system.

Key Components of an Ecosystem

• Producers (plants) are a key component
• Consumers (animals) form part of an ecosystem
• Decomposers (fungi, bacteria) are essential
• The physical environment (soil, water, air) is a key element

Major Terrestrial Ecosystems

• Forests, grasslands and deserts are major terrestrial ecosystems

Forests

• Tropical rainforests, located near the equator, have the highest biodiversity.
• Temperate forests undergo seasonal changes.
• Boreal forests (taiga) flourish in cold northern regions.

Grasslands

• Savannas have scattered trees and seasonal rainfall.
• Prairies feature deep, fertile soils and support grazing animals.

Deserts

• Hot deserts exhibit extreme temperature variations.
• Cold deserts receive little precipitation.
• Both hot and cold deserts demand unique adaptations for survival.

Major Aquatic Ecosystems

• Freshwater and marine ecosystems are major aquatic ecosystems

Freshwater Ecosystems

• Lakes are standing bodies of water divided into distinct zones.
• Rivers offer flowing habitats.
• Wetlands purify water and help prevent flooding.

Marine Ecosystems

• Oceans encompass 71% of Earth's surface with varying depths.
• Coral reefs sustain 25% of marine species.
• Estuaries serve as connectors between rivers and oceans.

Habitats Within Ecosystems

• Microhabitats and ecological niches exist within ecosystems

Microhabitats

• Microhabitats refer to small, specialized environments within ecosystems
• Fallen logs host fungi and insects in microhabitats
• Tree canopies create separate worlds
• Tide pools contain unique marine life

Ecological Niches

• An ecological niche is a species' role and position within an ecosystem.
• Niches have habitat requirements, feeding relationships, and behavior patterns.

Adaptations

• Adaptations are special features that help organisms survive in specific habitats.
• Physical adaptations include camouflage and body structures.
• Behavioral adaptations include migration and hibernation.
• Physiological adaptations include desert water conservation.

Biodiversity in Ecosystems

• Functional, species, and genetic diversity are all key to ecosystems

Types of Diversity

• Functional diversity refers to the variety of ecological processes.
• Species diversity is the variety of different species.
• Genetic diversity is the variety within a species.
• Biodiversity enhance ecosystem resilience and recovery from disturbances, they also maintain function through environmental changes.

Bioaccumulation

• Bioaccumulation is a silent threat where toxic substances enter the environment through pollution
• The substances include pesticides, heavy metals, and industrial chemicals

Bioaccumulation Processes

• Organisms absorb toxins through skin, gills, or consumption during absorption.
• These substances cannot be broken down or excreted.
• Toxins accumulate in tissues over time, and concentrations increase as organisms age

Biomagnification in Food Chains

• Producers, primary consumers, secondary consumers and apex predators are all impacted by toxins
• Plants absorb small amounts of toxins
• Herbivores accumulate higher concentrations of toxins
• Carnivores accumulate even higher amounts of toxins
• Apex predators suffer the highest toxin levels

Historical Impact from Toxins

• DDT in aquatic ecosystems nearly led to the extinction of bald eagles
• The pesticide concentrated up the food chain, causing deadly effects on top predators.

Effects of Bioaccumulation on Ecosystems

• Bioaccumulation disrupts hormones and wildlife development, causing population crashes.
• It also causes cascading effects throughout ecosystems

Negative Effects of Bioaccumulation

• 70% is roughly the birds affected by DDT's eggshell thinning from reproduction impact.
• 90% is roughly the Orca populations showing toxic contamination in some regions, which causes food web disruption.
• 30% is roughly the average immune function reduction in contaminated marine mammals from immune suppression

Invasive Species Introduction

• Invasive species enter in 4 steps:
• Introduction
• Establishment
• Integration
• Dominance

Steps of Introduction

• Introduction: a species enters a new ecosystem
• Establishment: reproduction and spread occurs
• Integration: the invasive species becomes part of the ecosystem
• Dominance: the invasive species outcompetes native species
• Invasive species arrive through international shipping, pet trade, and intentional introduction and can cause devastating effects.

Impact of Invasive Species on Native Organisms

• Invasive species impact native organisms through resource competition, predation, and habitat alteration

Types of Impacts from Invasive Species

• Resource Competition: invasives often outcompete natives for resources and may have few natural predators or diseases.
• Predation: Invasive predators can devastate native prey with no evolved defenses, particularly island species.
• Habitat Alteration: some invasives physically change habitats, and they may alter fire regimes, hydrology, or soil chemistry.

Lionfish in Atlantic Coral Reefs

• 1980s: First lionfish sightings occurred near Florida, likely from aquarium releases.
• 1990s-2000s: Rapid spread of lionfish occurred throughout Caribbean and Atlantic coastal waters.
• 2010s: Lionfish population explosion occurred, with densities up to 1,000 per acre in some areas.
• Present: Up to 80% reduction in native fish recruitment on affected reefs.

Environmental Changes

• Environmental changes includes the categories of:
• Climate Change
• Pollution
• Habitat Destruction
• Natural Events

Sources of Environmental Change

• Climate change involves rising temperatures, altered precipitation patterns, and extreme weather events.
• Pollution includes chemical, plastic, noise, and light pollution, that affects all ecosystems.
• Habitat destruction involves deforestation, urbanization, and agriculture converting natural areas.
• Natural events include volcanic eruptions, fires, floods, and other natural disturbances.
• Natural changes occur gradually allowing for adaptation but human-caused changes happen too rapidly for species to adapt.

Methods of Species Response to Environmental Changes

• Adaptation
• Migration
• Extinction

Effects of Species Response

• Adaptation: Genetic changes occur over generations, including behavioral or physiological adjustments, this requires time and genetic diversity.
• Migration: Movement to more suitable habitats occurs, this requires available corridors and new habitat, some species face barriers like mountains or cities.
• Extinction: Failure to adapt or migrate leads to population collapse, especially for specialists and species with small ranges, which causes the highest risk.

Environmental Stress

• Environmental stress: habitat loss, climate change, pollution, and invasive species.

Environmental Stress Effects

• Habitat Loss: causes crowding in remaining habitat, which causes a gradual population decline
• Climate Change: causes range shifts, which causes adaptation or local extinction
• Pollution: causes reproductive failures, which causes population bottlenecks
• Invasive Species: causes rapid decline of affected species, which causes community restructuring
• A genetic bottleneck occurs when population crashes dramatically, in which the surviving individuals represent only a fraction of original genetic diversity.

Extinction

• Extinction occurs when adaptation fails

Kinds of Extinction

• Local Extinction means: A species disappears from a specific area but survives elsewhere, which often precedes global extinction and may be reversible through reintroduction.
• Global Extinction means: The complete disappearance of a species from Earth, this is permanent and irreversible, resulting often from multiple pressures.
• The Sixth Mass Extinction means: Current extinction rates exceed natural background rates by 100-1,000 times, with up to 1 million species at risk.

Polar Bears and Climate Change

• Polar bears rely on sea ice as hunting platforms for seals.
• The ice provides their primary habitat and they rarely hunt successfully on land

Effects on Polar Bears because of Climate Change

• Arctic warming is double of the global rate, and summer sea ice could disappear completely by 2050.
• Extended ice-free periods means bears must fast, affecting their body condition and reproduction.
• The global polar bear population has decreased to around 22,000-31,000, with some subpopulations declining by 40%.

Conservation Strategies

• Strategies includes:
• Protection
• Restoration
• Reduction
• Research

Types of Strategies

• Protection strategies seek to: create protected areas and wildlife corridors, and enforce legal protections for threatened species.
• Restoration strategies seek to: rebuild damaged habitats, reintroduce native species, and remove invasive species.
• Reduction strategies seek to: decrease pollution and toxin release and limit greenhouse gas emissions and use sustainable practices.
• Research strategies seek to: monitor ecosystems, study threatened species, and develop conservation technologies.

The Future of Earth's Ecosystems

• Monitoring technologies use satellite tracking, environmental DNA, and AI to revolutionize ecosystem monitoring.
• These technologies help detect changes earlier and with greater accuracy.

Individual Actions

• Individuals can reduce their carbon footprint, choose sustainable products, and support conservation organizations.
• Each small action multiplies across population

Policy Changes

• Advocate for ecosystem protection, support science-based policies, and vote for leaders who prioritize environmental stewardship.
• The future depends on collective choices and humans have the power to protect ecosystems.