Marine Ecology: Organism Interactions & Ecosystem Dynamics

1. Chapter 10 Marine Ecology

2. Marine 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.

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

4. 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.

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

6. 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.

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

8. 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.

9. Purple _____ exhibiting _____ competition andRed (dark in photo)_____ exhibiting _____ with a ____

10. _____ competition between two hermit crabs fighting over a mollusk shell

11. 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.

12. 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) Ex. Two fish species feed on seaweed and one feeds faster and has more offspring until the second species is gone • they coexist (resource partitioning)

13. Resource partitioning - Competing species can coexist if they use the same resource in a slightly different way or at a different time. Ex. Two fish species that both eat seaweeds. One might specialize on brown algae while another might feed on red algae

14. Symbiosis - one species living in or on another. Types of Symbiosis: 1. Mutualism - both species _____ (example: cleaning associations). 2. Commensalism - one species benefits with no apparent effect on the other (example: barnacles living on whales; hermit crab). 3. Parasitism - one species benefits & the other is harmed (examples: tapeworms in the guts of whales).

15. More on Symbiosis • If partners in a symbiotic relationship can live without one another, this is known as facultative symbiosis (cleaning symbiosis). • If the partners cannot survive with the other partner, this is known as obligate symbiosis (marine lichens). • The smaller partner is known as the symbiont and the larger partner is called the host. Name each in a marine lichen.

16. PredationOne species (predator) kills another (prey) for food. • Prey species often have adaptations that help them avoid being eaten such as: • Warning coloration (lionfish we discussed in Fig. 8.10) • Camouflage (stonefish and flounder) • Physical adaptations (shells in mollusks) • Behavior (schooling)

17. Ecosystem All the _____ (living) and _____ (nonliving) components in a defined area. • Ecosystems interact. • All ecosystems require a constant input of energy. • Chemicals and nutrients are cycled within ecosystems.

18. Energy Flow • Energy flows through an ecosystem • Route of energy flow is determined by an ecosystem’s trophic structure.

20. 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.

22. 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.

23. 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 • Subtidal zone – always submerged; below the low tide level.

24. 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 Deep Sea zoned as bathypelagic (1000-4000m), abyssopelagic (4000-6000m) and hadopelagic (>6000m) where light does not penetrate. These will be discussed in the chapter on deep sea organisms.

25. 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. Can be estimated using gas detectors that measure carbon dioxide used or oxygen produced. • The total amount of phytoplankton in the water is called the standing stock. Can be measured by instruments that quantify chlorophyll in seawater. Also can be measured using satellite photographs.

26. Standing Stock (the total amount of phytoplankton) is estimated using instruments that detect chlorophyll or satellite photographs.

27. The Carbon Cycle • Carbon is required for primary producers to create organic molecules. • This carbon is cycled through an ecosystem. Carbon dioxide is released during _____ and decomposition. It is used by producers during ____.

29. 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. Nitrogen is fixed by bacteria and archaea. Most nitrogen and phosphorous compounds are produced during decomposition and excretion.

32. 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 like during red tides The effects of bioaccumulated materials are magnified through the food web (biomagnification).