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Chapter 10 Marine Ecology Rotting Douglas fir houses a community of insects, worms, fungi & microorganisms.

Marine Ecology Ecology is the interaction between organisms and their environment. These interactions affect the survival and distribution of these organisms. Organisms within a community interact with each other in very complex ways.

The physical place where an organism lives. Niche Community All populations of organisms living in a defined area. Habitat The physical place where an organism lives. Niche The resources (biotic & abiotic) an organism uses for survival, growth and reproduction.

Needs of a Species Populations demand specific resources to survive. These resources can affect population growth if they are in short supply. These resources that have the ability to affect the growth of a population are called limiting resources.

Needs of a Species The limiting resources can include, but are not limited to: Nutrients Light Space (habitat) Oxygen or carbon dioxide Inorganic compounds

Needs of a Species Even if an organism is able to acquire a limiting resource, there is a maximum number of organisms that any habitat can support. This number is known as the carrying capacity. As a population becomes more “crowded,” the growth rate of that population will decrease.

Marine Ecology Ways that Species can Interact: Competition Predator-Prey Interactions Symbiosis

Competition Competition occurs when organisms must “fight” with one another over a limiting resource they both require for survival. Organisms can compete with members of their own species – intraspecific competition – or members of other species – interspecific competition.

Competition An organism can use a resource at the expense of another organism. This may result in reduced ability of that individual to reproduce or even survive. Poorer competitors may die out due to this competition.

Interspecific Competition Individuals of different species compete for same resources (food, shelter, space). What are possible outcomes of interspecific competition? one individual excludes the other (principle of competitive exclusion) they coexist (resource partitioning)

More on Niches Fundamental niche - all resources a species is capable of using. Realized niche - all resources a species actually uses in a community. The realized niche may be different due to specific interactions with competitors. When Chthamalus is present (in absence of Balanus): Realized niche is fundamental niche - entire intertidal zone. When Balanus is present (in absence of Chthamalus): When both Chthamalus & Balanus are present: Fundamental niche of both is entire intertidal zone. Realized niche of Chthamalus is upper intertidal zone. [Chthamalus is better competitor in upper intertidal zone] Realized niche of Balanus is middle & lower intertidal zones. [Balanus is better competitor in middle & lower intertidal zones]

Resource partitioning - Competing species can coexist if they use the same resource in a slightly different way or at a different time. Five species of insect-eating warblers live in New England forests. They coexist in the same trees because each feeds in different ways & on different parts of the tree.

Types of Symbiosis: Symbiosis - one species living in or on another. 1. Mutualism - both species benefit (example: cleaning associations). 2. Commensalism - one species benefits with no apparent effect on the other (example: barnacles living on whales). 3. Parasitism - one species benefits & the other is harmed (examples: tapeworms in the guts of whales). Mutualistic relationship between squid (Euprymna scolopes) and bacteria (Vibrio fischeri) found in squid’s light-emitting organ. Bacteria are sheltered & fed, while the nocturnal squid evades predators or hides from prey as the glow from its bacterial passengers mimics moonlight coming from above. Commensalistic relationship between epiphytes & tall trees in tropical rain forests. Epiphytes (mosses & orchids) receive more sunlight in treetops than they would on the shaded forest floor. Trees are neither harmed nor benefited by presence of epiphyte.

More on Symbiosis If partners if a symbiotic relationship can live without one another, this is known as facultative symbiosis. If the partners cannot survive with the other partner, this is known as obligate symbiosis. In all cases, the smaller partner is known as the symbiont and the larger partner is called the host.

One species (predator) kills another (prey) for food. Predation One species (predator) kills another (prey) for food. Prey species often have adaptations that help them avoid being eaten such as: Warning coloration Camouflage Mimicry Predators differ from parasitoids in that they consume many prey over their lifetime. Camouflage helps prey blend in with background. They escape detection. Warning coloration advertises fact that the animal has defensive capabilities. Predators learn to avoid these distinctively colored prey (poison arrow frogs, bees, wasps, skunks, monarch butterflies). Mimicry occurs when different species develop similar appearances: harmless species that looks like a harmful species is protected only so long as its numbers remain fewer than the harmful species it mimics (these are ant-mimicking jumping spiders). many harmful species look alike (bees & wasps) - predator need only remember one color pattern.

All ecosystems require a constant input of energy. All the biotic (living) and abiotic (nonliving) components in a defined area. Ecosystems interact. All ecosystems require a constant input of energy. Chemicals and nutrients are cycled within ecosystems. Ecosystems can be large (biosphere) or small (single leaf).

Energy Flow Energy flows through an ecosystem Route of energy flow is determined by an ecosystem’s trophic structure. Trophic structure - feeding relationships; often depicted as a food chain. Majority of producers are photoautotrophs. Photoautotrophs are organisms that obtain carbon from inorganic sources & energy from sunlight; include plants, cyanobacteria & some protists. Chemoautotrophs are organisms that obtain carbon from inorganic sources & energy from chemical bonds; include hyperthermophilic bacteria & archaea found in hydrothermal vents on ocean floor. Scavengers eat remains of another’s meal; include vultures. Decomposers break down detritus (dead organisms & feces); include fungi, bacteria, insects & worms.

Where Does all the Energy Go? Is all of the energy stored by individuals at one trophic level available to the next? No - energy needs of individual take up most of the energy created or consumed. On average, ~10% (5-20%) is transferred to the next level of the food chain. Energy pyramid represents each trophic level by a volume directly proportional to the energy stored in new tissues per unit time. Energy pyramids can never be inverted (narrow base, broad top) because of the laws of thermodynamics.

Food chains rarely extend beyond four trophic levels except in the ocean community. Why?????? There is more biomass created at the bottom of the trophic level – at the primary producer level. Think of all the primary producers present in the marine community and the VAST stretches of ocean that support primary production. Therefore, the system can support additional secondary consumers.

Major Marine Environments Benthic organisms – live in/near bottom features This can be subdivided by the depth of the benthic zone. Examples: Intertidal zone – benthic zone located between high and low tide (therefore, this is exposed at least once a day – twice in NC!) Subtidal zone – always submerged; below the low tide level.

Major Marine Environments Pelagic organisms – live in the water column This zone, too, can be subdivided into different areas: Epipelagic zone- extends from the water’s surface to 100-200 m; plenty of sunlight available to support primary production Mesopelagic zone – extends from lower limit of epipelagic to about 1000 m; although sunlight is not plentiful, new research has shown that some photosynthesis does occur in this zone, although it is very reduced compared to the epipelagic zone. The bathypelagic, abyssopelagic and hadopelagic zones are deep sea zones where light does not penetrate. These will be covered in the chapter on deep sea organisms.

Measuring Primary Productivity The total amount of primary production is known as the gross primary production. The organic matter left over after the primary producers meet their own needs is the net primary production. This forms the base of the trophic pyramid. The total amount of phytoplankton in the water is called the standing stock (phytoplankton are the main primary producers).

The Carbon Cycle Carbon is required for primary producers o create organic molecules. This carbon is cycled through an ecosystem.

Nitrogen and Phosphorus Nitrogen and phosphorous are also required for primary production and must be cycled through an ecosystem. Figures 10.21 and 10.22 outline this cycling

Certain elements or compounds taken up by organisms cannot be metabolized or excreted. They accumulate in the organism (bioaccumulation) and may reach toxic levels. heavy metals (lead, arsenic, mercury) nonbiodegradable pesticides (DDT) Even toxins produced by organisms can be biomagnified The effects of bioaccumulated materials are magnified through the food web (biomagnification).