Intertidal Communities

Intertidal Communities Part of Chapters: 2, 4, 5, 11, 13, 20

Study of Ecology 0 • Environment: All of the living and non-living factors of an area. • biotic factors: living factors (animals, plants, fungi, ect) • abiotic factors: non-living factors (wind, temp, currents, salinity, ect) • Habitat: a place where an organism lives • Niche: the role an organism plays in their environment. No two species can have the exact same niche.

Populations and Communities 0 • Population : A group of the same species in a specified area. • Community : Many different populations in a specified area.

Populations and Communities 0 • Population growth • there are many ways in which a population can increase in size • Birth and immigration • exponential growth: drastic growth in a short period of time. • carrying capacity: the amount of organisms a specific area can support without running out or degrading resources.

Populations and Communities • Distribution of marine communities • pelagic division: all the water in the oceans • neritic zone: water above the continental shelf. • pelagic zone (oceanic zone): all the water pass the neritic zone (covers the deep areas) • photic zone: where sunlight can penetrate and support photosynthesis • disphotic zone: minimal sunlight can reach. Not enough for photosynthesis • aphotic zone: no sunlight • Plankton: organisms that drift with currents • Nekton: organisms that can swim against currents

Populations and Communities • Benthic division: The ground below the water in the oceans • Shelf zone: area that extends from high tide line to the continental slope • Bathyal zone: Below the shelf zone • Abyssal zone: Below the Bathyal zone (the deep) • Hadal zone: Below the Abyssal zone. Deepest areas in the oceans. Usually found in trenches. • Epifauna: Organisms that live on the sea bottom • Infauna: Organism that live in the sediment of the sea bottom

Characteristics of the Intertidal Zone • Daily fluctuations of the environment • organisms must tolerate radical changes in temperature, salinity and moisture, and endure the crushing force of waves • Inhabitants are most active during high tide, when area is submerged • water provides food for filter feeders • As the tide retreats, organisms adjust to exposure to air and sunlight

Environmental Factors Affect Organism Distribution 0 • Maintaining homeostasis (internal balance) • Affected by changes in external environment • internal adjustments made to maintain a stable internal environment • homeostasis and the distribution of marine organisms • Optimal range: • Zone of stress: • Zones of intolerance:

Environmental Factors Affect Organism Distribution 0 • Physical environment • sunlight • Photosynthesis • Vision • Desiccation • temperature • Ectotherms: • Endotherms:

Environmental Factors Affect Organism Distribution 0 • Salinity: • Solutes: • Osmosis: • Isotonic: • Hypertonic: • Hypotonic:

Environmental Factors Affect Organism Distribution 0 • metabolic requirements • nutrients and limiting nutrients • oxygen as a requirement for metabolism • anaerobic and aerobic organisms • Eutrophication: • metabolic wastes • carbon dioxide is a common byproduct of metabolism

Environmental Factors Affect Organism Distribution 0 • Biological environment • Competition • interspecific: • intraspecific: • competitive exclusion: • resource partitioning: • predator-prey relationships • balance of abundance of prey vs. predators • keystone predators:

Tides • Why tides occur • tides result from the gravitational pull of the moon and the sun • though smaller, the moon is closer to earth, so its gravitational pull is greater • water moves toward the moon, forming a bulge at the point directly under it • the centrifugal force opposite the moon forms another bulge • areas of low water form between bulges

Tides • Spring and neap tides • during spring tides, the times of highest and lowest tides, the earth, moon and sun are in a line, combining the pull of the sun and moon • when the sun and moon are at right angles, the sun’s pull offsets the moon’s, resulting in neap tides, which have the smallest change between high and low tide

Tides Types of Tides: • Diurnal: • Semidiurnal: • mixed semidiurnal: • Tidal range:

Waves • Wave formation • Wave: • Generating force: • most common = wind • also geological events, falling objects, ships • Restoring force:

Waves • deepwater and shallow-water waves • deepwater waves: • breakers • deepwater waves become shallow-water waves when they move into shallow water • surf zone: • breakers form when the wave’s bottom slows but its crest continues at a faster speed • plungers form when the beach slope is steep • spillers are found on flatter beaches

Waves • tsunamis • seismic sea waves are formed by earthquakes • tsunamis have long wavelengths, long periods and low height • compression of the wave’s energy into a smaller volume upon approaching a coast or island causes a dramatic increase in height

Intertidal Zonation • Zonation—separation of organisms into prominent horizontal bands defined by color or distribution of organisms • As tide retreats... • upper regions exposed to air, changing temperatures, solar radiation, dissication • lower regions exposed only a short time before tide returns to cover them

Intertidal Zonation • Supralittoral (maritime) zone: • Supralittoral fringe (splash zone):

Intetidal Zonation • Zone system (continued) • Midlittoral zone: • Infralittoral fringe: • Subtidal (infralittoral) zone:

Intertidal Fishes • Resident species • typically have special adaptations for surviving harsh intertidal conditions • small size; absent, reduced or firmly attached scales; compressed/elongate or depressed body shape; absent or reduced swim bladder; greater body density • tolerant of temperature and salinity changes • some intertidal fish can leave the water to feed • Temporary inhabitants • tidal, seasonal and accidental visitors

Rocky Shores and Sandy Shores • Rocky shores are found on the west coast from Alaska south and on the east coast cape cod north. • Have all 5 intertidal zones. Organisms attach to rocky surfaces and create a visiable zoning. • Sandy Shores are found mainly on the east coast, cape cod south and along gulf coast. • Only have 3 zones (Supralittoral zone, Midlittoral, Infralittoral zone). Does not show zonation because most organisms are found in the sand.

Role of Waves and Sediments • Sediment particle size influences the beach’s nature, porosity of sediments, ability of animals to burrow • Wave action influences sediment type: • heavy wave action = coarse sediments • little wave action = fine sediments • Beach slope results from interaction of waves, sediment particle size, and relationship of swash and backwash

Role of Waves and Sediments • Swash: • Backwash: • Types of beaches: • dissipative beach: • usually flat with fine sediment • reflective beach: • usually steep with course sediment

Role of Waves and Sediments • On all sandy beaches, a cushion of water separates the grains of sand below a certain depth • especially true on beaches with fine sand where capillary action is greatest • Fine sand beaches have a greater abundance of organisms • greater water retention • sediment is more suitable for burrowing

Meiofauna • Meiofauna: • Characteristics of the meiofauna • invertebrates from many phyla • generally elongated with few lateral projections • many are armored to protect them from being crushed by moving sand grains • include predators, herbivores, suspension feeders and detrivores

Linnaeus and Biological Classification • Binomial system of naming • binomial nomenclature: • introduced by Swedish botanist Karl von Linné (Carolus Linnaeus) in 1750 • e.g. Chaetodon longirostris (long-nose butterflyfish) and Chaetodon ocellata (spotfin butterflyfish) are both in the same genus

Linnaeus and Biological Classification • Taxonomic categories • Early schemes of classification • all living things were classified into 1 of 2 kingdoms, Animalia and Plantae, until 1960s • Modern classification • major categories: domain, kingdom, phylum, class, order, family, genus, and species • Domains: Archaea, Eubacteria, Eukarya • Kingdoms: Eukarya contains 4 kingdoms, Fungi, Plantae and Animalia, Protista • protists—eukaryotic organisms that do not fit the definition of animal, plant or fungus

Marine Reptiles • Reptiles adapted for success on land, then used the same characteristics to return to the sea and gain success there as well • Modern-day reptiles include: • crocodilians • turtles • lizards • snakes

Amniotic Egg • An amniotic egg is covered by a protective shell and contains: • Amnion: • yolk sac: • Allantois: • Chorion: • Copulatory organs allow efficient internal fertilization

Physiological Adaptations • Advanced circulatory system in which circulation through the lungs is nearly completely separate from circulation through the rest of the body • more efficient method of supplying oxygen • Kidneys are efficient in eliminating wastes while conserving water • Skin covered with scales and lacking glands decreases water loss

Marine Crocodiles • Best adapted to the marine environment is the Asian saltwater crocodile (Crocodylus porosus) • Large animals (up to 6 m long) • Feed mainly on fishes • Drink salt water and eliminate excess salt through salt glands on their tongues • Lives along the shore, where it nests

Sea Turtles • Adaptations to life at sea • protective shells that are fused to the skeleton and fill in the spaces between the vertebrae and ribs protect their bodies • outer layer of shell composed of keratin • inner layer composed of bone • Carapace: • Plastron: • leatherback turtle lacks shell and has a thick hide containing small bony plates

Sea Turtles • Adaptations to life at sea (continued) • shell is flattened, streamlined,d reduced in size and weight, for buoyancy/swimming • large fatty deposits beneath the skin and light, spongy bones add buoyancy • front limbs are modified into large flippers • back limbs are paddle shaped and used for steering and digging nests

Sea Turtles • Behavior • generally solitary, don’t interact • remain submerged while at sea; breathe air but can stay under water for as long as 3 hours • alternate between feeding and resting during the day • sleep on the bottom under rocks or coral

Sea Turtles • Feeding and nutrition • have a beak-like structure instead of teeth • green sea turtle is the only herbivore • leatherback sea turtles eat jellyfish • pharynx is lined with sharp spines to hold slippery prey • digestive system adapted to withstand stings • large amounts of salt consumed with food and water are eliminated as concentrated tears through salt glands above the eyes

Sea Turtles • Reproduction • courtship – males court females before mating; males may compete for a female, or 1 female may mate with several males • nesting – females dig shallow pits on the beach, usually at night, and bury eggs • development and hatching • temperature determines development time and sex ratio • hatchlings rush for the safety of the sea after hatching

Sea Turtles • Turtle migrations • females migrate from feeding grounds to the beaches where they were born to nest • green sea turtles feed on grasses in warm, shallow continental waters, but breed on remote islands • some breed on a 2- or 3-year cycle • method for navigation over long distances is unknown

Sea Turtles • Sea turtles in danger • beach erosion • artificial lighting near nesting beaches • sea turtles are killed when trapped in fishing nests, especially those used for shrimpers • turtle exclusion devices can reduce turtle mortality by as much as 95% when used for shrimp nets • turtles are hunted by humans for meat, eggs, leather and shells

Marine Iguana • The marine iguana of the Galápagos Islands off Ecuador is the only marine lizard • Most are black, but some are mottled red and black • dark coloration is thought to allow more absorption of heat energy • raising body temperature allows them to swim and feed in cold Pacific waters

Marine Iguana • Feeding and nutrition • herbivores with a short, heavy snout for grazing on dense mats of seaweed • swallow small stones to reduce buoyancy for feeding under water • excess salt from consumed seawater is extracted and excreted by specialized tear and nasal glands

Marine Iguana • Behaviors • good swimmers, using lateral undulations of the body and tail • each male occupies a small territory on the rocks, usually with 1 or 2 females • intruders or challengers are attacked when they enter the male’s territory • fights between male iguanas rarely result in serious injury

Sea Snakes • Adaptations to life in the sea • scales are absent or greatly reduced for streamlining • tail is laterally compressed into a paddle • nostrils are higher on the head • valves in the nostrils prevent water from entering when the snake is submerged • single lung reaches to the tail, and trachea is modified to act as an accessory lung by absorbing oxygen

Sea Snakes • Adaptations to life in the sea (cont.) • can exchange gases through the skin while under water • can lower metabolic rate to use less O2 • Feeding and nutrition • eat mainly fish and eels, sometimes eggs • most ambush prey and strike with venomous fangs • can swallow prey more than twice their diameter

Sea Snakes • Sea snakes and humans • sea snake venom is toxic to humans • being timid, sea snakes rarely bite humans; people eat them in Japan

Seabirds • 250 of 8,500 bird species are adapted to live near or in the sea • Seabirds feed in the sea • Some spend months away from land, but all must return to land to breed • Types of seabirds: • shorebirds • gulls and their relatives • pelicans and their relatives • tubenoses • penguins

Adaptations for Flight • Homeothermic: • Feathers aid in flight and insulate • High rate of metabolism to supply energy for active flight/nervous system • Strong muscles, quick responses, great deal of coordination • Advanced respiratory system with 4-chambered heart • Keen senses

Adapting to Life in the Sea • Large amounts of salt are consumed with food and salt water • salt glands above the eyes produce tears to remove excess salt • these tears have twice the salt concentration of seawater

Shorebirds • Waders with long legs and thin, sharp bills used to feed on intertidal organisms • Oystercatchers, curlews & turnstones • oystercatchers use long, blunt, vertically-flattened orange bills to slice through adductor muscles of bivalve molluscs • long-billed curlew uses its bill like a forceps to extract shellfish from burrows

Intertidal Communities