An Introduction to Marine Ecology

What is Ecology?Ecology is the

study of the interactions of organisms and their environment. The organisms presence & activities change the environment.

Abiotic Factors Biotic Factors

Non livingLightWaterTemperatureNutrientsOxygen/Carbon Dioxide

Other organisms

Organization in EcologyOrganismal ecology is concerned with the

behavioral, physiological and morphological ways in which individual organisms meet the challenges posed by physiochemical aspect of the environment. The organism’s limit of tolerance for environmental stresses ultimately determine where it can live.

Organization in EcologyPopulation – group of individuals in a

particular geographic area that belong to the same species; population ecology concentrates mainly on factors that affect population size and composition

Organization in EcologyCommunities

include all organisms and populations of different species in a particular area. Analysis at this level involves the ways in which predation, competition and other interactions among organisms affect community structure and organization.

Organization in EcologyEcosystems are composed of all biotic and

abiotic factors including how energy and nutrients cycle through the ecosystem.

Population GrowthExponential Growth – Fig. 10.2 – predicts

unlimited population increase under ideal condition of unlimited resources

Logistic population growth – Fig. 10-4 (red curve) – assumes that there is a maximum population size that the environment can support; the carrying capacity. Growth slows as the population size approached the carrying capacity.

Population Growth

What factors can act as limiting factors on population growth?

FoodWaterShelterTemperatureLightCompetitionNumber of organisms

Population Growth

Competitive exclusion – the concept that if two different populations of organisms are competing for the same limited resource, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population. (Fig. 10-5)

Regulation of Population SizeCompetition for Resources

Regulation of Population SizeCompetition for Resources

Resource partitioning – the division of environmental resources by coexisting species populations such that the niche of each species differs by one or more significant factors from the niches of all coexisting populations

Regulation of Population SizeCompetition for Resources

Regulation of Population SizeCompetition for Resources

Predation affects the numbers of both predator and prey; many predators concentrate on common species of prey because it is energy efficient

Regulation of Population SizePredation

Co-evolution – mutual influence on the evolution of two different species interacting with each other and reciprocally influencing each others adaptations

Regulation of Population SizePredation

Commensalism – one benefits without affecting the other

Regulation of Population SizeSymbiosis – two species that live together in direct

contact; symbiont and host

Parasitism – symbiont benefits at the expense of the host

Regulation of Population SizeSymbiosis

Mutualism – both symbiont and host benefit

Regulation of Population SizeSymbiosis

Tropic Structure – different feeding relationships in an ecosystem that determine the route of energy flow and the pattern of chemical cycling. Tropic levels are based on the main nutritional source. Tropic levels include:

ProducersConsumers (primary, secondary, tertiary)Decomposers

Energy Flow & Cycling of Nutrients

Producers are autotrophs, organisms that can make their own food. This is the trophic level that ultimately supports all other life.

Energy Flow & Cycling of NutrientsTrophic Structure

Consumers are heterotrophs, organisms that must obtain their food by eating autotrophs (primary consumers) or by eating other consumers (secondary/tertiary consumers)

Energy Flow & Cycling of NutrientsTrophic Structure

Decomposers break down waste products and dead organisms to release nutrients to primary producers

Energy Flow & Cycling of NutrientsTrophic Structure

Energy Flow & Cycling of NutrientsTrophic Structure

Why are the number of levels in any food chain limited to 3 to 4 levels?

Only 10% of the energy in one trophic level is passed to the next trophic level. The other 90% is used up by the activities of the organism

Energy Flow & Cycling of NutrientsTrophic Structure

Energy Flow & Cycling of NutrientsPyramid of Energy

Energy Flow & Cycling of NutrientsPyramid of Biomass

Energy Flow & Cycling of NutrientsPyramid of Numbers

Primary productivity is the amount of light energy converted to chemical energy by autotrophs; this is expressed as the amount of carbon fixed or the rate of synthesis of new biomass.

The total amount of organic carbon manufactured by primary producers is called the gross primary production.

Net primary production is the rate of photosynthesis minus the rate of respiration.

Energy Flow & Cycling of Nutrients

Biological, chemical, and geological processes move nutrients among organic and inorganic components. (Remember matter and energy cannot be created or destroyed, only changed.)

Energy Flow & Cycling of NutrientsCycling of Nutrients

Energy Flow & Cycling of NutrientsWater Cycle

Driven by solar energy, most of the cycle occurs between the oceans and the atmosphere through evaporation and precipitation. Its movementalso transfers other materialin biochemical cycles.

Energy Flow & Cycling of NutrientsCarbon Cycle

The reciprocal processes of photosynthesis and respiration are responsible for the major transformations and movement of carbon

Energy Flow & Cycling of NutrientsNitrogen Cycle

Most of the nitrogen cycling through food webs is taken up by photosynthetic organisms in the form of nitrate. Most of this comes from the nitrification of ammonium that results from the decomposition of organic material

Energy Flow & Cycling of NutrientsPhosphorus Cycle

No atmospheric component; tends to cycle locally from the weathering of rocks.

Classified on the basis of three physical criteria; light penetration, distance from the shore and water depth. These three criteria will determine what type of communities live in these areas.

Ecological Zonation of the Marine Environment