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Amphibian Population Decline: Initial Observations

• In 1995, a middle school class in Henderson, Minnesota, discovered deformed frogs.
• Findings indicated that 30-40% of these frogs had deformities, such as missing legs.
• Findings were reported to the Minnesota Pollution Control Agency.
• Deformed frogs were identified in 46 U.S. states, affecting over 60 amphibian species.
• Research from the 1980s and 1990s showed declining amphibian populations worldwide, including in pristine areas, signifying global concern.

Amphibians as Biological Indicators

• Amphibians' permeable skin makes them highly sensitive to environmental changes, including pollution and temperature shifts.
• Amphibians have dual aquatic and terrestrial habitats, which exposes them to multiple environmental stressors.
• Amphibian health reflects ecosystem stability and potential threats to other species, including humans.

Ruth and Sessions (Deformities and Parasite Hypothesis)

• Ribeiroia ondatrae, a trematode parasite, was linked to frog deformities.
• Experiment: Glass beads mimicking parasite cysts introduced into tadpoles resulted in similar deformities.
• Experiment results support the hypothesis that physical interference caused deformities
• Established a direct mechanism for deformities and identified parasites as a significant factor in amphibian decline.

Johnson et al. (Snails as Hosts and Nutrient Pollution)

• Research was conducted in Santa Clara, California, near San Francisco, surveying 35 ponds for amphibian populations and health.
• Pacific tree frogs were found in thirteen surveyed ponds, with four of these ponds containing frogs with deformities.
• All four ponds with deformed frogs contained the aquatic snail Helisoma tenuis, an intermediate host for the trematode parasite, pointing to a strong correlation.

Nutrient Pollution and Life Cycle Link

• Researchers initially hypothesized pollutants, such as heavy metals, pesticides, or PCBs, directly caused deformities.
• The shift in focus went to the role of the parasite-host dynamics after further review.
• Agricultural runoff containing nitrogen and phosphorus entered the ponds, leading to algal blooms.
• These algal blooms provided an abundant food source for snails, increasing their populations in affected ponds.
• Increased snail populations facilitated the life cycle of Ribeiroia ondatrae, serving as an intermediate host.
• The parasite's life cycle involves multiple hosts:
  • Snail Host- Ribeiroia releases free-swimming larval forms.
  • Amphibian Host- Larval parasites penetrate tadpoles, causing cyst formation that disrupts normal growth.
  • Definitive Host- The parasite completes its life cycle in bird or mammal predators which consume infected amphibians.
• Frogs with deformities dissected during these observations were consistently infected with Ribeiroia cysts.
• Controlled lab experiments replicated these findings by exposing tadpoles to Ribeiroia larvae, directly linking the parasite to the deformities.

Key Insights: Shift in Hypothesis

• Initial assumptions that pollutants cause deformities directly were disproven.
• Study redirected focus to the indirect effects of nutrient pollution (agricultural runoff).
• Nutrient runoff leads to algal blooms, increased snail populations, and causes higher Ribeiroia transmission.

Ecological Cascade

• Illustrates humans can indirectly impact ecosystems.
• Helisoma tenuis played a crucial role in the transmission of Ribeiroia and subsequent deformities in amphibians.
• Managing host populations and controlling nutrient pollution could mitigate the amphibian deformity issue.

Kiesecker's Experiments (Pesticides and Immune Suppression)

• To correlate pesticide presence in ponds with increased deformity rates and parasite susceptibility.
• Deformity Rates- Frogs in pesticide-exposed ponds showed higher deformity frequency, particularly in regions with higher pesticide levels.
• Linking Pollution to Health- Indicated that pesticide exposure impairs the frogs' ability to combat infections, such as those caused by Ribeiroia ondatrae.
• Ponds exposed to pesticides had more pronounced deformities due to the pollutants' synergistic effects on amphibian health and immune defenses.
• To isolate pesticide exposure effects on the immune system of amphibians.
• Tadpoles were exposed to laboratory conditions where some were exposed to sub-lethal dosages.
• Researchers assessed tadpole immune systems' response, focusing on parasite infection resistance.
• Reduced Immunity- Tadpoles exposed to pesticides showed significant decrease in immune function
  • This was measured by reduced ability to mount an immune response to the parasite.
• Increased Susceptibility to Infection- Tadpoles exposed to pesticides were more likely to develop infections, leading to deformities.

Indirect Effects of Pesticides

• Pesticides indirectly weaken the amphibian immune systems, making them vulnerable to infections from parasites like Ribeiroia ondatrae, suggesting that increasing deformities in pesticide-exposed areas are due to environmental stressors.

Synergistic Effects of Multiple Stressors

• Nutrient loading from agricultural runoff combines with pesticides exacerbates the effects of parasites, creating conditions called a "perfect storm" for amphibians:
  1. Nutrient Loading- Increased nutrients promote algal blooms, supporting the growth of snails involved in the parasite's life cycle.
  2. Pesticides- Impair the immune system of amphibians, reducing their ability to resist the parasite.
  3. Parasite Prevalence- Weakened immunity and increased parasite transmission result in higher deformity and mortality rates.
• Kiesecker's findings highlight interconnections through anthropogenic activities, demonstrate how interconnected human-induced changes can directly affect species' survival and ecosystem health.
• The decline in amphibian populations, influenced by these compounded factors, has broader implications for ecosystem health and biodiversity.
• Kiesecker's work emphasizes integrated conservation strategies. Requires reducing pesticide use, controlling nutrient pollution, and mitigating other anthropogenic pressures.

Factors Contributing to Declines

• Nutrient Runoff: Agricultural fertilizers increase algal growth, boosting snail populations and Ribeiroia infections.
• Pesticides: Weakens amphibian immune defenses, making them prone to parasites.
• Climate Change: Alters precipitation and temperature patterns, stressing ecosystems and facilitating pathogen spread.
• Habitat Loss: Reduces breeding and living spaces, intensifying population pressures.

Key Takeaways

• Interconnected Systems: Illustrates the interplay between pollutants, parasites, and ecological stressors.
• Ecological Research
  • Observational studies (e.g., pond surveys) provide initial insights.
  • Controlled lab experiments isolate causal factors.
  • Field experiments verify ecological relevance in natural settings.
• Broader Implications: Amphibian health serves as a sentinel for environmental and ecological.

Climate and Weather Defined

• Weather refers to short-term atmospheric conditions, including temperature, precipitation, humidity, and cloud cover.
• Climate represents the long-term patterns and averages of weather, measured over decades.
• An increasing trend in hurricane intensity is an example of how climate change is reflected.

Global Energy Balance

• The sun is primary energy source.
• Solar energy heats the Earth's surface, while Earth loses energy through outgoing infrared radiation.
• The energy gained from solar radiation must equal the energy lost to maintain a stable climate.
• Greenhouse gases trap heat by absorbing and re-radiating infrared radiation.
• Human activities have amplified the greenhouse effect, leading to a rapid energy imbalance, though this effect is essential for life.

Uneven Heating on Latitude

• Sunlight is concentrated and most effective on earth around the equator which most efficiently heats the surface.
• At higher latitudes, sunlight spreads over a larger area, cooling temps.
• Temperature gradients that drive atmospheric and oceanic circulation, redistribute heat and moisture globally.

Air Properties and Atmospheric Circulation Patterns

• Warm Air vs. Cool Air- Warm air is less dense and rises, while cool air sinks.
• Moist vs. Dry Air- Moist air contains water vapor, making it heavier than air.
• Tropical regions are hot and wet because at the equator, warm, moist air rises and cools.
• Rising air in the tropics descend around 30°N and 30°S, creating dry deserts is part of Hadley cell.
• Cold air that sinks at the poles creates high-pressure zones with minimal precipitation is part of Polar cell.
• Found in mid-latitudes and they produce temperate climates part of Ferrel cell.

Ocean Currents and Global Climate

• Winds drive surface ocean currents, moving heat and nutrients across the globe.
• The Gulf Stream transports warm water from the tropics to Northern Europe, moderating its climate.
• Downwelling: Warm, salty water sinks in polar regions, driving the global conveyor belt.
• Upwelling: Deep, nutrient-rich water rises to the surface, supporting marine ecosystems.
• Water absorbs and retains heat better than land, moderating temperatures.

Seasonality and Aquatic Environments

• Earth's 23.5° tilt relative to the sun causes seasonal changes in solar intensity and day length.
• Water is most dense at 4°C, leading to layers that resist mixing.
• In summer, lakes stratify into epilimnion, hypolimnion, and thermocline.
• When temperatures equalize during the spring and fall turnovers, mixing occurs, redistributing oxygen and nutrients.

Longer-Term Climate Cycles

• Key climate cycles impact global temperatures and precipitation patterns
• Trade winds weaken during El Nino.
• La Nina intensify normal trade wind patterns.
• The North Atlantic Oscillation (NAO). and Pacific Decadal Oscillation (PDO) also affects regions like Europe.

Regional Climate Trends

• Coastal areas experience mild, stable temperatures due to the moderating ocean.
• Inland regions have greater seasonal and daily temperature variation (continental climate).
• Temperature decreases with elevation due to lower air pressure and density.

The Rain Shadow effect

• Moist air rises and cools on the windward side of a mountain.
• The leeward side remains dry as descending air warms and holds less moisture.

Vegetation and Climate Interactions

• Albedo: Surfaces reflect solar radiation.
• Evapotranspiration: Plants release water vapor through transpiration.

Biomes are Communities

• Controlled by Climate:
• Terrestrial Biomes- Primarily determined by climate, especially average annual temperature and precipitation.
• Aquatic Biomes- Characterized by factors like water depth, flow, and salinity levels.

Terrestrial Biomes

Tropical Rainforest

• Location: Between 10° N and 10° S.
  • Abundant rainfall with one or two peaks annually
  • High biomass, holds almost 40% of terrestrial carbon
  • Forests often converted to pastures etc.

Tropical Seasonal Forests and Savannas

• Markes by seasonal rainfall, and deciduous foliage
• Fires and large animals shape savanna ecosystems
• Half of the system remains, with many lost to agriculture.

Deserts

• Water availability severely limits plant abundance
• Plant adaptation includes succulent stems for water storage
• Irrigation can lead to the salinization of soil

Temperate Grasslands

• Grasses dominate due to fires, with hot/cold climates
• Soil it highly fertile
• Overgrazing can cause regrowth

Temperate Scrubland and Woodlands.

• Cool, wet winters, with hot/dry summers
• Plants use Sclerophyllous leaves to deter herbivores
• Fire adaptation

Temperate Descisuos forets

• Dominated by descisuos trees that shed leaves in autumn and regrow in spring

Temperate Evergreen forects

• Adapted to nutrient poor soils
• Fire adaptation over200yrs, with some logging

Boreal Forests -Dominated by confter forests.

• Fires cause a lighting event
• Boreal wildfires impact on carbon

Tundra -Shorth sumers, perafrost limiting root space

• Arciti warming is disruptinf the cycle

Aquatic Biomes

• Riparian Vegetation: Provides organic matter, affects temp.
• Main Channel: Where swimming organizisms, adaptsble to currents and oxygen
• Benthic Zone: Larveal stage feedimg on organinc layer
• Source Streams: First order streams at high elevations.

Streams connect Terrestrial Systems

• Streams connected to marine systems, nutrients all around, categorized by minerals
• Detrius us important smaller streams
• Invertebrates break down stream in the headways
• In the Medium stream, collectors filter partcles
• Grazers are also consumers in the Medium Stream.
• Dominant bethic invertebrates, help in the collection.

Lakes

• Open ocean with Plankton
• Limeted at the zone by sun
• Nearshore, support plant
• Domiant, low sun at the bottom layer
• Phytoalankton in the photic zone, by bacteria and the zooplankton from the sun.

Marine Systems

• Cover 71 percdnt
• defined by depth, proximity
• Mix as freshwater, saltwater, with high conductivity Mangroves: habirs

The Open

• Photic, helps organizsm
• Nekton swiming plants Deep Ocean-Low temp/pressure

Biomes and Shifts

Tropical Rainforests- Decrease in area, in temp.

Tropical forest- more varied shifts

Deserts- Increase, over taking all.

Hadley

• latitude per decade . .1. at 30 degree N, expansion of approximate 38 degree if this expands, the temperature will also move forwrd with movement.

Adaptation

• Coping with Environmental Variations- Temp/Water Avoidance
• Temporary stress or locations Plants- Use life cycles .
• Animals use migrations.

Tolerance Ability through physiology .

Woolly plants in the tundras, uses a fluffy layer. Temp. Acclimation vs adaption- Temp- revisible change through stresses.

Ex- Gold fish acclimating

Adaption: The change is Irreversible.

Thermal Life

Limited life.

Internal Temps. typically range2 to 50. Freezing - cells burst and freeze. Ice fish and antifreeze preotins hot-

Enzymes - enyme desature for metabolism Stomats - Release c02 and water vapor leaf colors waxy coatings water broundryalys

Ethoherms vs Endothers

External vs Internal heat. High enregyy to keep production Berkmansl

Large to small Allen's Limnbs on size changes. Colder vs Warmer

Plant Cope with waster stress gravity potential

Osmotic/Matric potentials - to the soil layer Plant Cope with water stress. Stomtal c0 fertiliation effects.. During droight, plabrs store sugar inside cells,. CO fertizilation effevt for water storage.

Sources of Energy

• Converts sunlight into chemical

• Plants use sun, and the cyano bacteria. - energy.

• Energy by compunds or organisms.

• Dertivores consumes nonliving organic Parasites on live hosts Predatrs live and capute. Photosyntheiss H20+ CO2= C6H120+6O2 C6H120+ CO2 Rubisco: Most abundant enzyme on Earth that is crucial for CO2 fixation. Photosynhtesis and Light: Plants acclimate to different light levels. Light can be damaging if extra elcetrons are unused during this process. Adjust/change Leaf surface to reduce damage with temperature.

C3 Plants

Most Commen The rubisco binds both C2 and O2 More effeicnt in High Carbon C4 Pants minizes Waster losses. Efficient in Hot Dry CAM Plants takes at night C3 AND Came. Heteorptoph

Fat/cabrs

Evolution:

Populations change over time

Alleles Found at location frequency

Gene Flow allers. Mutation: Change of the data.

• Allers with the time.. Genentic Drift: Changes

Natural Selecton Benifical Traits.

Speciate Formation at new species. Genentric isollatoion

Limits to evolution Genetc Varation/ Cheetahs Constrain is the devlopmemt limitation, -cant devolpe. Trade Vetebrantes cant evole wheels off.

LifeH

• Patters and stracteis growth
• The coats also affect survivals
• Genetic. Age at first reproduction.

Amonut of Time.

High to Maintain populations Traits with energy organizing three stimutaeiousl;y

Morphs Alternative physicval of the organism. changes

A Sexual.

clones Advatagaes - quick

DisAdvatagaes- Low sexual Reproduction genetic code differe More energy than other animals

How Do Animals survive.

Parenntla Provisions Parenttal Care Studies: Marine Snail had larger ranges. The are alwasy a specialed stages

Insects often the speicalzafed for adults niches that to survival with food . Life Time, with different events

• Reprdouse and die and invest all ebery gho tme