Absolute density: Sample size is multipled by the habitat size to give an estimate of the total population.

Relative density: Samples have an unknown relationship to habitat size but can be compared to each other.

Protandry: Start life as a male but shift to female when larger. This is due to sperm being more easily produced than eggs, thus the smallest male has the potential to fertilize all of the eggs

Protogyny: Start life as a female but the largest female will shift to male and aggresively defend the harem.

Size selective fisheries means only one gender will be targeted, generally decreasing the overall size of individuals. In protandrous fish the number of females will be reduced, decreasing offspring numbers. In protogynous fish the males will be targeted, causing smaller females to shift to males. Therefore the overall size of females will be smaller, and egg count will be reduced.

Ascidian eggs exist in two forms. Either large or small.

1/2 of the eggs were exposed to high sperm. Large eggs suffered arrested developement due to polyspermy.

1/2 of the eggs were exposed to low sperm. Small eggs were rarely fertilized.
Eggs of multiple sizes could occur to help mediate seasonal flucuations in sperm numbers.

Semelparity: One reproductive event per lifetime.

Iteroparity: Multiple reproductive events per lifetime.

Ocean stabilty hypothesis:

Calm, stable oceans results in patches of food and thus good survival.

Match-mismatch hypothesis:

Planktonic blooms and spawing peaks do not run simultaneously. When they do match up there is a peak in recruitment.

Member-vagrant hypothesis:

Ocean circulation transported larvae offshore or retained them. If retention is strong large populations were formed. If retention was limited there was greater vagrancy.

Open: Planktonic larvae, larvae found great distances from origin, larvae recruitment is highly unpredictable.

Closed: Self-sustaining populations of invasive species, local endemic species, population genetics, stock-recruitment relationships, environmental tags.

That different processes could be responsible for species distribution; dispersal, habitat selection, species interactions or abiotic conditions. Transplantation experiments were used to distinguish these.

Eg. Connells barnacles

1. Diffusion: Gradual movement across hospitable terrain.

2. Jump dispersal: Movement over large, inhospitable distances, followed by the establishment of a population.

3. Secular dispersal: Very slow. Linked with evolutionary patterns.

Numeric response: Increased reproduction

Aggregative response: Change in movement pattern

Developement response: Increased growth and maturation

Functional response: Change in consumption pattern

Development of a host-parasite relationship.

Developement of a predator-prey relationship.

Co-existing species developing a system of mutal benefit.

1. Growth form and structure.

2. Diversity.

3. Dominance (overall numbers, competion, structrally important or through behaviour).

4. Relative abundance of species.

5. Trophic structure.

1. Facilitation model: Species cause changes in the environment, making it more suitable for other species to invade.

2. Inhibition model: Species resist invasion by later successional species, making succession only possible after a disturbance event.

3. Tolerance model: Late successional species invade because they can tolerate lower resource levels and can out-compete earlier successional species.

Phase shift: A change in thershold conditions causes the state of a community to shift to another single state. Eg. coral to macroalgae shift in the tropics.

Alternative stable states: One environment can host two (or more) communities, however only one is present, depending on the starting conditions. Eg. Urchins can survive off drift kelp, but when drfit is low or urchin abundance is high, urchins actively forage causing 'barrens' to form.

1. Niche diversification model: Strong competition leads to increased specialisation and narrow ecological niches.

2. Lottery model: Success is the result of chance occupation of vacant space.

3. Predation-disturbance model: Death is high enough to ensure populations never undergo competitive exculsion.

4. Recruitment limitation: Larval supply is never sufficient for adult populations to reach carrying capacity.

Enteromorpha is prefered Littorina food source over Chondrus. Enteromorpha is dominant competitor in tide pools but Chondrus is dominant on emergent substrate.

With high Littorina abundance in tide pools Chondrus became dominant. Greatest diversity in tide pools was when Littorina abundance was at intermediate levels.

However, on emergent substrate grazing resulted in reduced diversity as only Chondrus is present.

Integrated model of community structure:

When the environment is harsh, physical factors dominate and in any given environment these factors are more important when recruitment is low.

When the environment is moderate and recruitment is low competition and predation are unimportant. When Recruitment is high competition and predation are important.

Alpha diversity: Within a habitat

Beta diversity: Between habitats

Human introduction of substances or energy into the marine environment resulting in one or more of the following:

Harm to living resources

Hazards to human health

Hinderance of marine activities

Poor water quality

Organic waste: Sewage, oil, etc

Conservative waste: Toxins

Dissipating waste: Hot water

Inert soild waste: Dredging soil, ash, etc

Weather: Trade winds relax, reversing water build up. Increased rainfall in the East, leading to flooding. Drought occurs in the West (East coast of NZ). The Pacific has an increased number an more intense storms.

Marine systems: Thermocline in the East becomes lower, decreasing productivity. Thermal and nutrient stress may affect benthic communities eg. coral bleaching. Migration patterns and species interactions are altered.