5/10/15 Chapter 16: Marine Communities

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Chapter 16: Marine Communities

Biomes and Ecosystems Biomes are defined as "the world's major communi'es, classified according to the predominant vegeta;on and characterized by adapta;ons of organisms to that par;cular environment" (Campbell, 1996). Examples are marine, desert, forest.

An Ecosystem is a dis;nct en;ty (smaller than a biome) with defined physical boundaries, dis;nct abio;c condi;ons, an energy source, and a community of interac'ng organisms through which energy is transferred (ex: ;de pool, estuary; coral reef)

http://www.scienceclarified.com/Di-El/Ecosystem.html

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Marine Communi'es

•  Marine Organisms Live in Communi;es •  Communi;es Consist of Interac;ng Producers, Consumers, and Decomposers

•  Marine Communi;es Change as Time Passes •  Organisms in Communi;es Can Live in Symbiosis

Marine Communi'es Key terms (1)

•  A community is comprised of the many popula;ons of organisms that interact at a par;cular loca;on.

•  A popula2on is a group of organisms of the same species occupying a specific area.

•  A habitat is an organism’s “address” within its community, its physical loca;on. Each habitat has a degree of environmental uniformity.

Marine Communi'es Key terms (2)

•  An organism’s niche is its “occupa;on” or role within that habitat, its rela;onship to food and enemies, an expression of what the organism is doing.

•  Physical (abio;c) and biological (bio;c) factors in the environment determine the loca;on and composi;on of a community.

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Physical and Biological Environmental Factors

•  A proper balance of physical and biological factors is important for the success of each organism and the community.

•  Different organisms have different tolerances for specific factors.

•  Steno- is a prefix meaning “narrow”. It can be used to describe organisms that have narrow tolerances for specific factors

•  Eury- is a prefix meaning “wide”. It can be used to describe organisms that have wide tolerances for specific factors

Range of tolerance to a physical factor – in this case, temperature – for a popula;on of organisms.

Range of Tolerance

Growth Rate and Carrying Capacity Are Limited by Environmental Resistance

The J-‐shaped curve of popula;on growth of a species is converted to an S-‐shaped curve when the popula;on encounters environmental resistance. The physical or biological condi;ons responsible for the cessa;on of growth are called limi;ng factors.

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Popula;on Density and Distribu;on Depend on Community Condi;ons

Random, clumped, and uniform popula;on distribu;on paYerns. The clumped paYern is most common in nature; uniform is the rarest.

Marine Communi;es Change with Time •  Changes can occur slowly due to climate

cycles or seafloor spreading, or quickly due to factors such as volcanic eruption.

•  A climax community is a stable, long established community.

•  If a climax community is disrupted, it may be restored through the process of succession.

The Ocean Supports Many Communi;es

•  Rocky intertidal communities •  Seaweed communities •  Sand beach and cobble beach communities •  Salt marsh and estuary communities •  Coral reef communities •  Open ocean communities •  Deep sea floor communities •  Hydrothermal vent communities

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Inter;dal Communi;es Are Densely Populated despite Environmental Rigors

The inter2dal zone -‐ the band between the highest high-‐;de and lowest low-‐;de marks on a rocky shore -‐ is one of Earth’s most densely populated areas. A Pacific coast ;de pool and inter;dal shore.

Coral Reefs Are the Most Densely Populated and Diverse Communi;es

The coral reef habitat.

© 2011 Pearson Educa;on, Inc.

Coral Reefs

•  Reefs – shallow water communi;es restricted to tropics and subtropics

•  Polyps – individual corals

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Coral Reef Distribu'on


Condi;ons for Coral Reef Development

•  Warm (but not hot) seawater •  Sunlight (for symbio;c algae) •  Strong waves or currents •  Clear seawater •  Normal salinity •  Hard substrate


Importance of Coral Reefs

•  Largest structures created by living organisms – Great Barrier Reef, Australia, more than 2000 km (1250 miles) long

•  Great diversity of species •  Important tourist locales •  Fisheries •  Reefs protect shorelines

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Coral Reefs in Decline

•  30% healthy today, 41% healthy in 2000 •  One third of corals – high risk of ex;nc;on •  Humans – greatest threat

– Global warming – Ocean acidifica;on

•  Coral bleaching •  Other threats

– Hurricanes – Floods – Tsunami

Symbio'c rela'onships In coral reef ecosystems

•  Symbiosis (Greek roots sym: “together with” and bio: “living”) is a close, prolonged associa;on between organisms of different species that may benefit one or both members (parasi;sm; commensalism; mutualism).

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Parasi'sm (+, -‐) •  Parasi2sm: benefits one species and harms the other (+,-‐).

•  Examples: the Sea Lamprey feeding on the blood of a host fish; the isopod feeding on the tongue of a host fish

Commensalism (+, 0) •  Commensalism is a rela;onship in which one partner derives some benefit while the other is unaffected. Ex: the man-‐of-‐war fish, which lives among the tentacles of the Portuguese man-‐of-‐war; the remora, which aYaches itself to larger pelagic animals including sharks and rays for protec;on, transporta;on and scraps of food.

A bebarnacled gray whale. [Credit: m_uhlig, Flickr.com]

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Mutualism (+, +) •  Mutualism is a symbio;c rela;onship in which both organisms benefit. The organisms may be animals, plants, algae or bacteria. Ex: the clown fish and the anemone; coral polyps and zooxanthellae (algae); and cleaner shrimp, which clean a wide variety of other parasites from reef fishes such as the moray eel.

MUTUALISM AND HOUSING The fish and the shrimp live together in a symbiotic relationship where the shrimp digs and cleans up a burrow and the fish warn the almost blind shrimp against predators.

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MUTUALISM AND TRANSPORTATION The crab carries a pair of sea urchins in its claws. When predators approach the crab, it waves the urchins, which present their sharp spines. The crab gets protection and the sea urchins get the particles of food that are dropped by the crab. The urchin gets transported to more food sources.

COMMENSALISM AND CAMOUFLAGE The seahorse is camouflaged by the sea fan, avoiding predation. Seahorse benefits and no harm is done to the host.

PARASITISM, HOUSING AND TRANSPORTATION The barnacle penetrates the crab’s shell rendering the crab infertile and impairing the crab’s normal molting process. The female barnacle will lay her eggs in the crab’s pouch. The crab’s instinct will be to continue along caring for the eggs as if they were her own.

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PARASITISM AND HOUSING The pearl fish is a type of mesoparasite. It detects chemicals given off by the sea cucumber and enters the sea cucumber when it participates in gas exchange and breaths in water. The sea cucumber attempts to eject the pearl fish by expelling most of their digestive tract out through their anus. This can be detrimental for the sea cucumber.

Evolu'onary significance

•  Mutualism and commensalism are hypothesized to have originated from parasi'c rela;onships.

•  If this is true, then host organisms, through evolu;onary adapta;on, selected traits that allowed them to take advantage of parasi;c behavior and that led to mutually beneficial rela;onships in some cases.

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5/10/15 Chapter 16: Marine Communities