Temperate Deciduous Forest Overview PDF

Lecture 10- Temperate Deciduous Forest Overview ​ Found in moderate climates. ​ Dominated by hardwood deciduous trees. ​ Key Characteristics: ○​ Four distinct seasons. ○​ Nutrient-rich soils from annual leaf fall. ○​ Moderate precipitation and temperature promote decom...

Lecture 10- Temperate Deciduous Forest Overview ​ Found in moderate climates. ​ Dominated by hardwood deciduous trees. ​ Key Characteristics: ○​ Four distinct seasons. ○​ Nutrient-rich soils from annual leaf fall. ○​ Moderate precipitation and temperature promote decomposition. ○​ High biodiversity compared to boreal forests. Seasons and Climate ​ Spring: Sunlight reaches understory due to seasonally leafless trees. ​ Summers: Warm temperatures. ​ Winters: Cold and snowy. ​ Precipitation is moderate and evenly distributed throughout the year. Biodiversity ​ Producers: Primarily plants, with trees being the focus. ​ Consumers: ○​ Numerous birds and small mammals. ○​ Larger mammals include grazers and carnivores/scavengers. ​ Decomposers: ○​ Fungi and invertebrates such as insects, worms, gastropods, crustaceans, nematodes, etc. ​ Fallen plant material, fruits, and litter enrich the soil community throughout the year. Tree Species and Distribution ​ Trees in these forests are of mixed age and species. ​ Deciduous Trees: ○​ Drop leaves in winter. ○​ Examples: Maple, Oak, Beech, Elm. ​ Coniferous Trees: ○​ Retain leaves through winter. ○​ Examples: Red and White Pine, Hemlock, White Cedar. ​ Ontario’s Great Lakes-St. Lawrence Forest Zone: ○​ Mixing zone between deciduous and boreal forests. ○​ Varied tree species present due to the transitional nature. ​ Historical Impact:  ○​ Pine forests were heavily cultivated for logging during colonization. Plant Evolution and Land Plants ​ Land plants evolved approximately 470 million years ago from green algae. ​ Early Challenges: ○​ No method for obtaining water from soil. ○​ Limited capacity to restrict water loss. ○​ Constant threat of desiccation. ​ Phylogeny of Land Plants: ○​ Monophyletic group descended from green algae. ○​ Two Main Groups: 1.​ Bryophytes (non-vascular plants). 2.​ Vascular Plants (Tracheophyta). Vascular Plants (Tracheophyta) ​ Synapomorphy: Presence of vascular tissue (xylem and phloem). ​ Four Groups of Vascular Plants: ○​ Lycophytes. ○​ Ferns. ○​ Gymnosperms. ○​ Angiosperms. ​ Vascular Tissue: ○​ Extends from roots to leaves. ○​ Organized in rings near the stem's exterior. Xylem ​ Carries water and minerals upwards from roots to leaves. ​ Structure: ○​ Hollow conduits with lignin for structural support. ○​ Nucleus and cytoplasm are lost during development. Phloem ​ Carries photosynthates (sugar-rich sap) downward from leaves to roots. ​ Transports: ○​ Carbohydrates, amino acids, nitrogen, ions, hormones, and RNA. ​ Structure: ○​ Sieve elements lose intracellular structures, including the nucleus, during development. Tree Growth and Structure ​ Primary Growth: ○​ Increases height and length. ​ Secondary Growth: ○​ Increases diameter via vascular cambium. ○​ Produces new xylem and phloem. ○​ Forms wood, enabling structural support and material movement. ​ Growth Rings: ○​ Seasonal differences in xylem cell size create rings (e.g., larger spring wood cells). Gymnosperms vs. Angiosperms ​ Both are seed-producing vascular plants. Gymnosperms ​ Seeds develop on cones. ​ Pollination by wind. ​ Male and female cones contain pollen and ovules, respectively. ​ Examples: Pines, Yews, Junipers, Cedars. Angiosperms ​ Seeds develop inside fruits. ​ Flowers hold pollen and ovules. ​ Pollination Methods: ○​ By wind, water, or animals (e.g., insects and vertebrates). ​ Co-evolution: ○​ Flowers and pollinators evolved together, increasing diversity. ​ Fruits: ○​ Protect immature seeds. ○​ Enhance dispersal via color, odor, or structures. Seed Dispersal Mechanisms ​ Gymnosperms: ○​ Seeds fall to the ground or are wind-dispersed with specialized structures.  ​ Angiosperms: ○​ Fruits facilitate dispersal by animals, wind, or water. ○​ Fleshy fruits: ​ Brightly colored and odorous to attract animals. ○​ Dry fruits: ​ Dispersed whole, in parts, or split open to release seeds. Pollen and Reproduction ​ Pollen Dispersal: ○​ Gymnosperms: Wind-pollinated. ○​ Angiosperms: Pollination by wind, animals, or water. ​ Seed Development: ○​ Gymnosperms: Seeds develop on cones. ○​ Angiosperms: Seeds develop within fruits. Key Concepts in Plant Lifecycle ​ Alternation of Generations: ○​ Plants alternate between haploid and diploid phases. ○​ Both phases undergo mitosis. ​ Seed Plant Life Cycle: ○​ Dominated by diploid (2n) stage. ○​ Gametes: Pollen (male) and ovule (female). ○​ Zygote develops into an embryo within the seed. Lecture 11- Temperate Deciduous Forest (Morris et al., Ch. 27, 32, 34) General Characteristics ​ Higher biodiversity compared to Boreal forests. ​ Key contributors to the forest food web: ○​ Producers: Primarily plants, especially trees. ○​ Consumers: ​ Birds (numerous species, both top and lower consumers). ​ Small mammals (e.g., rodents). ​ Larger mammals (e.g., grazers, carnivores, scavengers). ○​ Decomposers: Fungi and invertebrates (e.g., insects, worms, gastropods, crustaceans, nematodes). Birds General Characteristics ​ Approximately 10,000 species globally. ​ Features: ○​ Bipedal vertebrates with feathers. ○​ Toothless bills covered with a horny sheath. ○​ Larger brains (6-11x size compared to similar-sized reptiles). ○​ Complex behaviors. ○​ Anatomical adaptations: ​ Forelimbs modified into wings (lift and propulsion). ​ Efficient respiratory system for high oxygen needs. ​ Hollow, lightweight bones for rigidity and reduced weight. ​ Specialized bills adapted for different diets. Bird Categories 1.​ Palaeognathae: Large flightless birds (e.g., emu, ostrich) and smaller flying tinamous. 2.​ Galloanserae: ○​ Galliformes: Pheasants, turkeys, quail, chickens. ○​ Anseriformes: Ducks, geese, swans. 3.​ Neoaves (all modern birds except Galloanserae and Palaeognathae): ○​ Telluraves (land birds): Passeriformes (perching birds), raptors (e.g., eagles, hawks), owls. ○​ Aquaterraves (waterbirds and others). Roles in Forest Food Web  ​ Top Consumers (Raptors): ○​ Examples: Hawks, eagles, falcons, owls. ○​ Diet: Carnivorous or scavengers feeding on smaller animals. ○​ Traits: Excellent eyesight, talons, curved beaks, sexual dimorphism, build stick nests. ​ Lower Consumers: ○​ Songbirds (Passeri): ~3,000 species; use complex songs to communicate and claim territory. ​ Sexual dimorphism: Females often dull-colored for predator evasion. ​ Diet: Insects, invertebrates, fruits, nuts, seeds. ​ Predators: Birds of prey, mammals (e.g., coyotes, foxes), even herbivores like deer. ○​ Woodpeckers (Picidae): Specialized feeders; some reside year-round (e.g., nuthatch, sparrows, blue jays). Mammals (Mammalia) General Characteristics ​ Key traits: ○​ Hair and mammary glands. ○​ Internal fertilization; care for young until independence. ○​ Warm-blooded; regulate body temperature internally. ○​ Sweat glands (reduced in aquatic mammals/thick-furred species). ​ Hair characteristics: ○​ Made of keratin (same as nails, hooves, horns). ○​ Patterns (e.g., spots, stripes) provide camouflage. ○​ Specialized hairs: ​ Vibrissae (whiskers) for tactile sense. ​ Porcupine quills (barbed, easily detachable). Specific Mammals in Temperate Deciduous Forests 1.​ Rodents: ○​ Porcupines: Arboreal, feeding on twigs, leaves, berries. ○​ Chipmunks: Seed hoarders, promote forest regeneration, opportunistic predators. 2.​ Deer (Cervidae): ○​ Herbivores feeding on leaves, nuts, shoots, grasses. ○​ Adaptable to various environments, including urban. ○​ Can consume poison ivy and mushrooms due to specialized ruminant stomachs. 3.​ Hibernation and Torpor: ○​ Hibernation: Long-term body temperature/metabolic rate reduction during food scarcity.  ○​ Torpor: Short-term "temporary hibernation" due to low food availability and cold temperatures. Horns and Antlers ​ True Horns: ○​ Ruminants (e.g., sheep, cattle). ○​ Keratinized sheaths covering a bony core. ○​ Grow continuously, typically not: Mammals (Continued) Horns and Antlers (Continued) ​ Antlers: ○​ Found in deer (Cervidae). ○​ Composed of solid bone when mature. ○​ Develop annually in spring, covered by "velvet" (highly vascularized soft tissue). ○​ Velvet is shed by rubbing antlers against trees once growth is complete. ○​ Typically only males produce antlers, except in caribou. ○​ Antlers are used for mating displays and competition. Reptiles and Amniotes Reptiles Overview ​ Key traits: ○​ Ectotherms: Depend on environmental heat sources. ○​ Lay shelled eggs (oviparous); some species are ovoviviparous or viviparous. ○​ Sensitive to vibrations and olfaction; generally poor eyesight and hearing. ​ Examples in temperate forests: ○​ Snakes (Squamata; Serpentes): ​ Limbless vertebrates with highly kinetic skulls (loosely jointed jaws). ​ Predators of invertebrates, amphibians, small mammals, and birds. ​ Preyed upon by birds of prey and carnivorous mammals. Amniotes ​ Key characteristics: ○​ Produce shelled eggs preventing moisture loss. ○​ Egg adaptations: ​ Outer shell (leathery or mineralized).  ​ Amniotic membrane enclosing the embryo in a fluid-filled cavity. ​ Chorion for gas exchange and waste management. ​ Nutrition provided by yolk or placenta. ○​ Internal fertilization (sperm cannot penetrate the eggshell). ​ Additional adaptations: ○​ No gills in larvae → fully terrestrial life cycle. ○​ Thick, waterproof skin with no capability for cutaneous respiration. ○​ Lungs are the primary respiratory site. Fungi (Morris et al., Ch. 32) General Characteristics ​ More closely related to animals than plants. ​ Key traits: ○​ Produce chitin in cell walls. ○​ Heterotrophic: Feed on other organisms (not photosynthetic). ○​ Reproduce sexually and asexually. ○​ Enormous diversity: ​ ~150,000 described species; estimated >2.2 million species. ​ Organized into ~10 phyla. Ecological Roles ​ Carbon Cycling: ○​ Break down complex molecules in plant/animal tissue using released enzymes. ○​ Absorb simple organic molecules through cell walls. ​ Plant Interactions: ○​ Mycorrhizal relationships: Symbiotic interactions where fungi provide nutrients to plants in exchange for sugars. ○​ Leaf litter decomposition. ​ Other Roles: ○​ Agricultural pests. ○​ Used in fermentation (e.g., yeast for alcohol production). Fungal Structures and Reproduction ​ Hyphae: ○​ Rapidly growing network forming the mycelium. ○​ Can become extremely large and diffuse. ​ Spore Production: ○​ Triggered by resource shortages. ○​ Produce massive numbers of spores to maximize dispersal chances.  ​ Fruiting Bodies: ○​ Above-ground reproductive structures (e.g., mushrooms, brackets, cups). ○​ Formed from densely packed hyphae. ○​ Elevation aids in spore dispersal. Soil and Leaf Litter Creatures ​ Rich in microbial and invertebrate life. ​ Includes insects, worms, gastropods, nematodes, and crustaceans. ​ Supports nutrient cycling and decomposition. Lecture 12- Urban Landscapes General Overview ​ Urban areas are full of life but typified by disturbance. ​ Characteristics of urban landscapes: ○​ Human-propagated plant monocultures are disrupted by resilient pioneer species. ○​ Both native and non-native species coexist. ○​ Pressures faced by urban organisms: ​ Pollution, physical barriers (pavement), human interaction. ​ Adaptation to urban heat islands: ​ Cities are 10-15°C warmer than surrounding rural areas. ​ Causes: Concrete/asphalt absorbing heat, combustion, indoor heating. ​ Increased rainfall and significant runoff (requires drainage systems). ○​ Urban microhabitats: ​ "Natural" or human-made. ​ Additional nutrient inflows but also greater nutrient loss. Responses to Urban Life ​ Organisms adapt in three main ways: 1.​ Avoid: Example: Wolves.  2.​ Adapt: Example: Raccoons, red foxes. 3.​ Exploit: Example: Pigeons, rats. Urban Flora and Fauna Plants ​ Desirable plants: Trees, grass, ornamental flowers. ​ Less desirable plants: Weeds. ​ Traits of successful urban plants: ○​ Grow quickly from seed. ○​ Tolerate high nutrient/toxic contaminant levels. ○​ Rely on wind or human distribution for seed dispersal. Lichens ​ Composite organisms: Symbiosis of fungi/yeast (mycobionts) and cyanobacteria/green algae (phycobionts). ​ Characteristics: ○​ Polyphyletic, not fitting standard monophyletic classifications. ○​ Found in extreme habitats (bare rocks, arctic slopes). ○​ Photosynthesize at temperatures as low as -18°C and survive as low as -198°C. ○​ Slow-growing and sensitive to urban pollution (e.g., acid rain). ○​ Serve as indicators of air quality in cities. Earthworms (Phylum Annelida, Class Clitellata) ​ Characteristics: ○​ Segmented body (metameres/somites). ○​ Movement: ​ Circular muscles elongate segments. ​ Longitudinal muscles shorten segments. ​ Setae (4 pairs per segment) act as anchors. ○​ Important ecological roles: ​ Break down organic matter, mix and aerate soil. ​ Serve as food for birds, amphibians, mammals. ○​ Reproduction: ​ Hermaphroditic, sexual reproduction (direct development without metamorphosis). ​ Clitellum secretes mucus for mating; forms a cocoon for eggs. Insects (Phylum Arthropoda, Class Insecta) ​ Characteristics:  ○​ Body sections: Head, thorax, abdomen. ○​ Most have 2 pairs of wings on the thorax. ○​ Highly diverse and adaptable: ​ Found in almost all habitats except the open ocean. ​ Flight enabled wide distribution. ○​ Feeding habits: ​ Herbivorous, predaceous, parasitic, or scavenging. ​ Some are pests or disease vectors. ○​ Reproduction: ​ Sexual reproduction, often involving pheromones, bioluminescence, or courtship. ​ Metamorphosis: Complete (holometabolism) or incomplete (hemimetabolism). ​ Diapause: Annual dormancy period triggered by environmental cues. Arthropods and Spiders Spiders (Order Araneae, Subphylum Chelicerata) ​ Key traits: ○​ Six pairs of appendages (chelicerae, pedipalps, walking legs). ○​ Silk spinning: ​ Spinnerets produce silk for webs, egg sacs, prey capture. ​ Silk is strong and stretchable. ○​ Reproduction: ​ Sexual reproduction with elaborate courtship rituals (e.g., jumping spiders). ​ Sexual cannibalism is common. ​ Eggs laid in silken webs; juveniles molt multiple times before adulthood. ○​ Ecological importance: ​ Consume 400-800 million tonnes of prey (mainly insects) annually. Ticks and Mites (Order Acari) ​ Characteristics: ○​ Fusion of cephalothorax and abdomen, no external segmentation. ○​ Life stages: Eggs → 6-legged larvae → 8-legged nymph → Adults. ○​ Ticks in urban environments: ​ Found in long grass, forest edges, deer travel areas. ​ Black-legged ticks transmit Lyme disease. Lecture 13- Urban Ecology Urban Adaptation Among Mammals and Birds ​ Over 55% of the human population lives in urban areas, which cover 3% of Earth’s land surface. ​ Urbanization effects: ○​ Habitat fragmentation. ○​ Reduced species diversity. ○​ Increased species invasions. ○​ Loss of native species. ○​ Convergent evolution causes urban populations to resemble distant urban sites more than surrounding nonurban areas. Studying Urban Evolution ​ Historical Perspective: ○​ Early ecologists viewed cities as “anti-life” and ignored urban ecology. ​ Urban pressures on evolution: ○​ Pollution increases mutation rates, potentially accelerating evolution. ○​ Fragmented ecosystems result in smaller populations, promoting genetic drift. Genetic Drift and Population Structure ​ Effects of genetic drift in urban populations: ○​ Reduced within-population diversity. ○​ Increased divergence between populations. ​ Observed examples: ○​ White-footed mice (Peromyscus leucopus). ○​ Yellow toadflax (Linaria vulgaris). Evolutionary Urban Innovation ​ Urban environments introduce unique pressures, leading to novel adaptations. ​ Social learning: ○​ Learning through observation of others’ behaviors. ○​ Example: Great tits (Parus major) learned to open puzzle boxes for food, with subpopulations conforming to initial behaviors. Raccoons (Procyon lotor) and Urban Adaptations  ​ Traits: ○​ Nocturnal, omnivorous generalists. ○​ Excellent climbers; socially learned behaviors. ○​ Prefer deciduous forests, riparian edges, and avoid alpine habitats. ○​ Store fat in tails and enter torpor in winter. ​ Urban selective pressures: ○​ Higher reproductive rates, lower mortality. ○​ Mortality causes: ​ Vehicular collisions. ​ Disease (e.g., canine distemper virus). ​ Animal control measures (euthanasia). ​ Diseases: ○​ Raccoon rabies variant prevalent in the eastern US. ○​ Urban ranges smaller than rural ones (male ranges > female ranges). Genetic Trends in Urban Populations ​ Red fox (Vulpes vulpes): ○​ Urban populations have reduced genetic diversity due to smaller sizes and genetic drift. ○​ Similar patterns observed in other species, like rodents. Ecological Traps ​ Cooper’s hawks (Accipiter cooperii): ○​ Attracted to urban areas due to prey abundance. ○​ Face increased mortality from: ​ Window collisions (365-988 million bird deaths/year in the US; 16-42 million in Canada). ​ Organophosphate poisoning targeting pigeons. ​ Trichomoniasis infection from eating Inca doves. Founder’s Effects ​ Common blackbird (Turdus merula): ○​ Urban colonization occurred independently multiple times. ○​ Populations show reduced genetic diversity due to founder effects. Life History Trends in Urban Birds ​ Study of 3768 bird species across 137 cities: ○​ Urban species trends: ​ Smaller body size. ​ Broader dietary and habitat niches. ​ Larger clutch sizes (fecundity selection). ​ Greater longevity. ​ Less territorial, more dispersal ability. ​ Common urban bird species: ○​ Feral pigeon, house sparrow, barn swallow, osprey, peregrine falcon. Peregrine Falcon (Falco peregrinus) ​ Fastest animal on Earth (dive speeds: 320 km/h). ​ Urban adaptations: ○​ Specialize in hunting urban prey (pigeons, parakeets, ducks). ○​ Threats: Collisions with buildings, vehicles, power lines. ○​ Territorial combat is the leading cause of adult mortality. Urban Carnivores ​ Bobcats (Lynx rufus): ○​ Roads act as barriers to gene flow. ○​ Population bottlenecks result from disease (e.g., mange) and anticoagulant poisoning (rodenticides). Cats as Invasive Species ​ Domestic cats (Felis catus): ○​ Global population: ~90 million in the US alone. ○​ Listed among the 100 worst invasive species. ○​ Ecological impacts: ​ Responsible for 14% of bird, mammal, and reptile extinctions on islands. ​ Estimated predation rates: ​ 228-871 million reptiles/year. ​ 1-5 billion birds/year. ​ 5-25 billion mammals/year. Urban Management Strategies ​ Wildlife underpasses or corridors: ○​ Facilitate gene flow between fragmented populations. ○​ Studies show reduced collisions near underpasses. ○​ Higher collision rates in fenced areas compared to unfenced zones. ○​ Herbivores/omnivores have higher collision frequencies than carnivores Lecture 13- Marine Ecology: Coral Reef Study Guide Coral Reefs Overview Geological Importance ​ Massive physical structures. Biological Importance ​ High diversity and biological structure. Economic Importance ​ Shoreline protection, harbors, fishing, tourism. Coral Reef Composition ​ Assemblages of skeletons and sediment of sedentary organisms, compacted and cemented. ​ Constructional, wave-resistant features. ​ Built primarily by corals, coralline algae, sponges, and other organisms.  ​ Reef-building corals: ○​ Belong to Order Scleractinia (Stone Coral). ○​ Contain endosymbiotic algae (zooxanthellae). ○​ High calcification rate. ​ Topographically complex. Coral Reef Structure and Growth Order: Scleractinia ​ Secrete skeletons of calcium carbonate. ​ Colonies of similar polyps, interconnected by cenosarc tissue. ​ Polyps: ○​ Can regenerate asexually. ○​ Exist in corallite cups. ○​ Sit in colonies and grow via cenosarc tissue. Coral Growth Forms ​ Encrusting, massive, branching, foliaceous. ​ Polymorphic forms influenced by growing conditions. ​ Growth rates: ○​ Branching corals: ~10 cm/year. ○​ Massive corals: ~1 cm/year. Coral and Zooxanthellae Symbiosis Coral Side ​ Mutualistic relationship with zooxanthellae. ​ Tentacles for heterotrophic feeding. ​ Coenosarc passes nutrients between polyps. ​ Epidermis contains nematocysts for prey capture. Zooxanthellae Side ​ Enveloped by coral through phagocytosis into a vacuole (symbiosome). ​ Prevents fusion with lysosomes. ​ Benefits to coral: ○​ Radiocarbon-labeled carbon is taken up and transported. ○​ Production of glucose and amino acids. ○​ Facilitation of calcification through CO2 uptake. Coral Growth Factors and Limitations Distribution ​ More abundant along eastern continental margins. ​ Environmental requirements: ○​ Average salinity (~35 ppt). ○​ Sea surface temperature: ≥20°C. ○​ High light levels for symbiosis. ○​ Low turbidity and strong currents. Challenges ​ Ocean acidification. ​ Sea-level changes. ​ Competition between growth and bioerosion. Coral Reef Types ​ Shelf reefs: Along continental margins. ​ Oceanic reefs: ○​ Fringing reefs. ○​ Barrier reefs. ○​ Atolls. Coral Reef Reproduction Asexual ​ Fragmentation: Broken pieces grow. ​ Budding: Growth within colonies. Sexual ​ External spawning (synchronous). ​ Brooding fertilized eggs. ​ Hermaphroditic or dioecious species. ​ Mass spawning: ○​ Gametes released synchronously. ○​ Mechanism to reduce predation. Coral Zonation Vertical and Horizontal Variations ​ Different species dominate at various depths. ​ Factors: ○​ Light conditions. ○​ Wave action. Coral Reef Decline and Threats Natural Disturbances ​ Hurricanes and large storm waves. ​ Catastrophic mortality events. Anthropogenic Disturbances ​ Coastal development and agricultural runoff. ​ Overfishing leads to macroalgae overgrowth. ​ Pollution and sedimentation. Coral Bleaching ​ Causes: ○​ Temperature stress. ○​ Disease. ​ Mechanisms: ○​ Expulsion of zooxanthellae. Global Warming Impact ​ Massive die-offs, e.g., 2016 Great Barrier Reef event. ​ Over 50% of corals lost in the last century. Coral Predation and Grazing Crown-of-Thorns Starfish (Acanthaster planci) ​ Eats coral, leaving scars colonized by algae.  ​ Causes of outbreaks: ○​ Nutrient loading from heavy rainfall. ○​ Overfishing of predators (e.g., prawns). ○​ Shell collection impacting Giant Triton populations. Coral Reef Fisheries and Diversity Fish Diversity ​ Coral reefs support diverse fish species and communities. ​ Roles: ○​ Protection. ○​ Feeding. ○​ Reproduction. Fishing Statistics ​ Global catches peaked in 2002. ​ Overfishing leads to algae-dominated ecosystems. ​ Coral reefs at risk of overfishing (~60%). Preservation of Coral Reefs Challenges ​ Climate change and ocean acidification. ​ Overfishing and pollution. ​ Adaptation potential if given time to acclimate. Lecture 14- Marine Ecology: Clines and Adaptations Study Guide The "Salt" in Saltwater Composition of Seawater ​ ~96.5% pure water. ​ Dissolved and suspended materials include: ○​ Particulate mineral matter. ○​ Inorganic salts (ions): Cl⁻, Na⁺, SO₄²⁻, Mg²⁺, Ca²⁺, K⁺. ○​ Dissolved gases (N₂, O₂, CO₂). ○​ Particulate and dissolved organic matter (POM & DOM). Forchhammer's Principle (1865) ​ Major salts occur in constant proportions, even with varying salinity. ​ Salinity variations arise from addition/removal of water, not salt content. Salinity ​ Measured in parts per thousand (‰) or practical salinity units (psu). ​ Average: 35‰ in open oceans (40‰ in the Red Sea). ​ Influencing factors: ○​ Evaporation, precipitation. ○​ River input, freezing/thawing of sea ice. ​ Density increases with salinity. Global Variations in Salinity ​ Surface salinity varies with latitude: ○​ Equator: Lower salinity (high precipitation). ○​ Subtropics: Higher salinity (high evaporation). ○​ Polar regions: Freshwater input from ice melt. ​ Vertical salinity gradients: ○​ Halocline: Rapid change in salinity with depth. Ocean Temperature Heat Capacity ​ Water’s high heat capacity moderates climate. ​ Resistant to phase changes. Temperature Range ​ Oceans: -2°C to 40°C. ​ Deep oceans: 2-4°C. ​ Latitudinal gradient: Higher temperatures at the equator. Thermocline ​ Layer where temperature changes rapidly with depth. ​ Stratification: ○​ Warmer, variable saline water near the surface. ○​ Cooler, consistent saline water at depth. Pycnocline ​ Vertical gradient in water density. ​ Influenced by temperature and salinity. Water Masses Definition ​ Large volumes of water with unique temperature, salinity, and density properties extending over thousands of kilometers. Examples in the Arctic Ocean ​ Arctic/Polar water. ​ Atlantic water. ​ Arctic Bottom water. Impact of Freshwater Input ​ Localized oceanographic and biological changes. Osmoregulation Maintaining Osmotic Balance ​ Osmoconformers: ○​ Match body fluids to seawater (e.g., sharks). ○​ Use urea to increase ionic concentration. ○​ Trimethylamine N-oxide (TMAO) counters urea’s destabilizing effects. ​ Osmoregulators: ○​ Actively regulate salt and water. ○​ Strategies: ​ Marine mammals use renal systems. ​ Fish/crustaceans excrete salt through gills and kidneys.  ​ Birds/reptiles use salt glands to excrete NaCl. Examples ​ Sharks: ○​ Blood is isotonic or slightly hypertonic to seawater. ○​ Store urea in blood. ​ Marine mammals: ○​ Derive water from diet, regulate via renal systems. ​ Fish: ○​ Chloride pumps in gills excrete salts. ○​ Diadromous fish (e.g., salmon) transition between freshwater and marine environments. ​ Birds & Reptiles: ○​ Salt glands excrete excess NaCl through nostrils or mouth. Organic Osmolytes ​ Substitute for inorganic ions to regulate cell volume. ​ Examples: ○​ Sharks: Urea. ○​ Seaweeds: Glycerol, mannitol. ○​ Invertebrates: Free amino acids. Thermoregulation Types of Organisms ​ Poikilotherms: Body temperature varies with the environment. ​ Homeotherms: Maintain constant body temperature. ​ Ectotherms: Gain heat from the environment. ​ Endotherms: Generate heat internally. Adaptations ​ Endothermic animals (e.g., common thresher shark): ○​ Use medial red muscle for heat generation. ○​ Retia mirabile countercurrent exchange maintains temperature gradients. ​ Birds: ○​ Feathers trap air for insulation. ○​ Oil preening maintains waterproofing. ​ Marine mammals: ○​ Dense fur and blubber. ○​ Countercurrent heat exchange minimizes heat loss. Examples ​ Common Thresher Shark: ○​ Generates body heat in core muscles. ○​ Red muscle is aerobic and myoglobin-rich. ○​ Retia mirabile system prevents heat loss. ​ Greenland Shark: ○​ Lives in deep, cold waters. ○​ High TMAO concentration makes meat toxic. Adaptations in Marine Environments Waterproofing & Insulation ​ Birds: ○​ Downy feathers trap air for insulation. ○​ Oil spills compromise insulation and buoyancy. ​ Mammals: ○​ Blubber provides insulation and energy storage. ○​ Reduced appendages minimize heat loss. Surviving Extreme Conditions ​ Arctic sea ice melting impacts temperature and salinity gradients. ​ Adaptations like countercurrent systems are crucial for thermoregulation. Lecture 15- Freshwater Streams: Study Guide Overview of Freshwater Streams Freshwater Biomes ​ Types: ○​ Lakes (lentic systems: still water). ○​ Rivers/streams (lotic systems: moving water). ​ Variability influenced by: ○​ Climate and topography. ○​ Nutrient input and oxygen availability. Characteristics of Rivers and Streams ​ Defined by moving water. ​ Size and chemistry vary greatly. ​ Water chemistry influenced by terrain and runoff. ○​ Nutrient levels range from low to very high. ​ Primary freshwater inputs: ○​ Rain and groundwater. ○​ Runoff (main nutrient source). ​ Oxygen levels: ○​ Generally high due to currents. ○​ Lower in slower-moving floodplain rivers. River Composition Microhabitats ​ Created due to non-linear flow: ○​ Pools, runs, riffles, rapids. ○​ Water column, benthos, riparian zone (transition between terrestrial and river habitats). Factors Affecting River Conditions ​ Light: Clarity varies with productivity and input from surrounding environments. ​ Sediment: Movement and mixing impact turbidity. ​ Nutrient Levels: ○​ Natural sources: Weathering, erosion. ○​ Human impacts: Fertilizers, urban runoff, wastewater. ​ Oxygen Levels: ○​ Natural sources: Mixing, submerged plants, algae. ○​ Limited by: Warm water, stratification, organic pollution (measured as Biochemical Oxygen Demand or BOD). Producers in Streams Primary Producers ​ Photosynthetic organisms: ○​ Large/small plants and algae along margins. ○​ Phytoplankton in the water column. Key Phytoplankton Groups ​ Cyanobacteria: ○​ Oxygenic phototrophs with chlorophyll a. ○​ Accessory pigments: Carotenoids, phycocyanin, phycoerythrin. ○​ Cell structure: ​ No organelles; photosynthesis occurs on thylakoid membranes. ​ Morphology ranges from unicellular to filamentous forms. ○​ Specialized cells: ​ Akinetes (resting stage). ​ Heterocysts (nitrogen fixation in anaerobic conditions). ​ Eukaryotic Algae: ○​ Green Algae: ​ Characteristics: ​ Chlorophylls a, b; carotenoids. ​ Starch storage. ​ Cell walls of cellulose and pectin. ​ Morphological trends: ​ Unicellular, colonial, filamentous, multicellular. ○​ Stramenopiles (e.g., Diatoms): ​ Diverse group with silica skeletons (frustules). ​ Responsible for 25% of Earth’s photosynthesis. ​ Features: ​ Chlorophylls a, c; chrysolaminarin storage. ​ Mostly asexual reproduction. ​ Found in marine and freshwater environments. River Consumers Key Groups ​ Insects (major consumers). ​ Other invertebrates: Crustaceans, gastropods, bivalves. ​ Vertebrates: Fish, turtles, birds. ​ Filter feeders play a significant role in nutrient cycling. Ecological Processes and Human Impacts Nutrient Cycling ​ Natural sources: Weathering, erosion. ​ Anthropogenic sources: ○​ Urban and agricultural runoff. ○​ Wastewater discharge. ​ Excess nutrients can cause eutrophication and oxygen depletion. BOD and Organic Pollution ​ High BOD indicates high organic pollution. ​ Leads to oxygen stress for aquatic organisms. Climate Change and Rivers ​ Impacts on water temperature and oxygen levels. ​ Altered flow patterns affect sediment and nutrient distribution. Lecture 16- Freshwater Streams Consumers in Rivers ​ Interaction of aquatic and terrestrial carbon cycles.  ○​ Leaves entering streams. ○​ Organisms with life stages in both environments. ○​ Terrestrial animals preying in streams and vice versa. ○​ Animal waste and remains entering water. 2. Freshwater Animals as Indicators of Environmental Disruption Amphibian Decline ​ One-third of amphibian species threatened with extinction. ​ Characteristics making amphibians sensitive: ○​ Narrow environmental tolerances. ○​ Gas exchange through skin. Contributing Factors ​ Habitat destruction. ​ Pesticides. ​ Fungal infections. ​ Invasive species. ​ Runoff from construction, agriculture, and road salt. ​ Land-use changes and climate change. Bioassessment ​ Identification of living organisms to assess habitat health. 3. Conservation Biology Biodiversity Loss ​ Diminished biodiversity leads to: ○​ Less productive and resilient communities. ○​ Loss of opportunities for novel compound discoveries (e.g., medical, industrial). ​ Human reliance on biodiversity for sustenance. Biodiversity Hotspots ​ Areas with high indigenous species richness. ​ Priorities for conservation efforts. Ecosystem Services  ​ Cleaner air and water. ​ Greater primary productivity. ​ Improved resilience to environmental disruption. ​ Untapped resources for medicine and agriculture. Human Impact ​ Growing ecological footprint challenges. ​ Need for informed choices to preserve the natural world. ​ Diverse careers addressing ecological and biological challenges: ○​ Field biologists, ecologists, geneticists, engineers, teachers. 4. Subphylum Vertebrata (Craniata) Characteristics ​ Cranium enclosing the brain. ​ Cartilage or bone-based endoskeleton: ○​ Allows larger body size. ○​ Provides muscle attachment for movement. ​ Evolution of bone: ○​ Stronger than cartilage for muscle attachment. ○​ Likely evolved for mineral regulation (e.g., calcium, phosphorus). Major Vertebrate Classes ​ Jawless fishes (hagfish, lamprey). ​ Cartilaginous fishes (sharks, skates, rays). ​ Bony fishes (trout). ​ Amphibians (frogs). ​ Reptiles and birds. ​ Mammals. 5. Teleost Fishes (Class Actinopterygii) General Characteristics ​ Account for 96% of all living fishes; half of all vertebrates. ​ Found in diverse environments (high altitudes to ocean depths, -2°C to 44°C). ​ Marine and freshwater species. ​ Specialized adaptations: ○​ Scales, fins, and tails for exceptional mobility.  ○​ Modified jaws for diverse prey types. ○​ Swim bladder for buoyancy and sensory functions. Feeding ​ Most are carnivores (zooplankton, insect larvae, smaller fish). ​ Cannot chew food; swallow prey whole to maintain gill water flow. Reproduction ​ Predominantly dioecious with external fertilization. ​ Some species exhibit: ○​ Ovoviviparity (embryo develops in egg within mother). ○​ Viviparity (placental attachment for live birth). ○​ Oviparity (laying numerous eggs externally). Salmon in Canada ​ Cultural and economic significance. ​ Anadromous lifecycle: ○​ Grow in sea, spawn in freshwater. ○​ Atlantic salmon: repeated spawning. ○​ Pacific salmon: spawn once, then die. ​ Threats: logging, farming, pollution, hydroelectric dams. 6. Transition from Bony Fishes to Tetrapods Key Adaptations ​ Bone replacing cartilage. ​ Swim bladder evolved into lungs. ​ Double circulation system for oxygenated and deoxygenated blood. ​ Skull, teeth, and limb modifications for land movement. Terrestrial Adaptations ​ Stronger backbones and limb girdles. ​ Protective rib cages. ​ Airborne sound detection via modified ears. 7. Modern Amphibians (Class Amphibia) General Characteristics ​ Over 6,000 species in three orders. ​ Dependent on water: ○​ Moist habitats for eggs. ○​ Gilled larvae. Orders 1.​ Salamanders (O. Urodela): ○​ Primarily in temperate regions. ○​ Aquatic larvae; terrestrial adults. ○​ Carnivorous (worms, arthropods, molluscs). 2.​ Frogs and Toads (O. Anura): ○​ Must live near water. ○​ Tailless, jumping adults with aquatic tadpoles. 8. Molluscs (Phylum Mollusca) General Characteristics ​ Over 90,000 living species. ​ Mantle produces shell and houses gills/lungs. ​ Diverse classes include gastropods, bivalves, and cephalopods. Gastropods ​ Largest mollusc class (>70,000 species). ​ Diverse roles: algae scrapers, prey, and predators. ​ Coiled shells (dextral or sinistral). ​ Respiratory adaptations: ctenidia (gills), lungs. Bivalves ​ ~9,000 species (marine, freshwater, brackish). ​ Sedentary filter feeders using gill cilia. ​ Reproduction: ○​ Trochophore and veliger larval stages. ○​ Freshwater species have glochidia larvae, parasitic on fish gills. ​ Conservation concern: zebra mussels as invasive species. 9. Conservation and Human Impact ​ Biodiversity hotspots critical for preservation. ​ Ecosystem benefits: cleaner air/water, resilience to disruption. ​ Careers in biology (fieldwork, molecular research, education). ​ Importance of advocacy for sustainable policies.