MARINE ENVIRONMENTS

Marine Biologists categorize communities according to WHERE and HOW organisms live.



Benthic (or benthos) – organisms that live on or buried in the bottom



Sessile – attached organisms (do not swim)

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Pelagic – organisms that live higher in the water column (away from the bottom)

Pelagic organisms are further divided according to how well they swim.

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Plankton – organisms that swim weakly



Drift in water

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Phytoplankton (example: algae) – most important primary producers in marine ecosystem

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Zooplankton – small heterotrophic organisms

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Nekton – animals that can swim well enough to oppose currents



Mostly vertebrates

Classification of the Benthic Environment

Benthic environment on continental shelf is divided into 2 regions:

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Intertidal (or littoral) zone – boundary between land and sea;

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shallowest part of the continental shelf

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At the mercy of the tides

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Subtidal (or sublittoral) zone – continental shelf beyond the intertidal zone

The Benthic environment beyond the continental shelf is called

“

the deep sea floor

”

.



Abyssal Zone – deepest environment of sea floor



< 4,000 meters deep



Organisms in the abyssal zone are adapted to extremely cold temperatures and high pressures.

Classification of the Pelagic Environment – by depth



Neritic Zone – pelagic environment that lies over the continental shelf



Less than 300 meters deep

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Oceanic Zone – waters beyond the shelf

Classification of the Pelagic Environment – by amount of light



Photic zone - depths which receive sufficient light to support photosynthesis

 

100-200 meters deep Phytoplankton thrive in this area – producing food for the rest of the ecosystem



Aphotic zone - depths that receive insufficient light to support photosynthesis

Zonation in a Marine Environment

Plankton

An Introduction to the Drifters

What are plankton?



Planktos

– Greek meaning “ to wander ”  Weakly swimming or drifting organisms  Microscopic or macroscopic in size  Plant (phytoplankton) or animal (zooplankton)

Why are plankton important?

 Food source (basis of the food web)  Producer of oxygen (photosynthesis)  Cause of toxic “ blooms ” (resulting in fish kills and shellfish poisoning)  Means for dispersal of organisms by transport in currents  Major players in the global carbon cycle

How are plankton studied?

 Collected with sampling bottles  Special nets  Microscopes  Cultured in labs Photo by: Lisa Wu Students aboard the R/V Slover in the southern Chesapeake Bay

Collection Methods

 Fish and invertebrate larvae (net plankton) are collected during plankton tows  Depth, distance towed, and the volume of water sampled must be calculated  Mesh sizes of nets vary depending upon what is being researched This plankton net is being deployed to collect near surface plankton in Maug caldera. The net is about 2 m (6.5 ft) long and has a mesh size of 236 microns (0.25 mm or 0.01 in).

The large aluminum frame of the neuston net is 1 meter high and 3 meters long. Here the net is being deployed off the starboard side of the

R/V Seward Johnson

Collecting Plankton

Bongo nets are towed over the side of the ship or carried by divers to collect drifting organisms

Image ID:

fish1014, NOAA's Fisheries Collection

Photo Date:

1987

Photographer:

Captain Robert A. Pawlowski, NOAA Corps

Image ID:

nur05536, Voyage To Inner Space - Exploring the Seas With NOAA Collect

Photographer:

J. Morin

Credit:

OAR/National Undersea Research Program (NURP) Deploying Bongo nets for sampling plankton

Can plankton be studied from space?

    Satellites equipped with color scanners measure the concentration of chlorophyll in the ocean Red = high concentration of chlorophyll Chlorophyll is the major pigment for photosynthesis in phytoplankton Data provides information concerning biomass, productivity, and changes in plant populations Satellite Image of the Gulf of Maine

Phytoplankton blooms observed in the Atlantic Ocean off Africa

Image ID: spac0361, NOAA In Space Collection 2003 May 2

Do organisms spend their entire lives as plankton?

 

Holoplankton

spend their entire life cycle as plankton. Examples include: dinoflagellates, diatoms and krill

Meroplankton

spend only a part of their life cycle drifting. As they mature they become nekton (free swimmers) or benthic (crawlers) Examples include: fish and crab larvae.

Charleston Bump Expedition. Zooplankton, crab larva. Image ID:

expl0172, Voyage To Inner Space - Exploring the Seas With NOAA Collect

Location:

Southeast of Charleston, South Carolina

Photo Date:

2003 August 7

Photographer:

Jerry Mclelland

Credit:

Charleston Bump Expedition 2003. NOAA Office of Ocean Exploration; Dr. George Sedberry, South Carolina DNR, Principal Investigator

Plankton Observation Worksheet

Specimen # ___________ Characteristics: Description Body shape/Tail/flagella/appendages/eyes Transparency/gills/other features ______________________ ______________________ ______________________ Circle one from each category: Phytoplankton or Zooplankton Holoplankton or Meroplankton sketch

Examples of Plankton Specimen #1

Specimen #2

Specimen #3

Specimen #4

Specimen #5

Specimen #6

Specimen # 7

Specimen #8

Specimen #9

Specimen #10

Intertidal Communities



Most studied and best understood marine environment

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Intertidal – part of the sea floor that lies between the highest and the lowest tides

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Unique due to regular exposure to air

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The size and species composition of the intertidal will vary with degree of exposure

Organisms must be adept at surviving in these arid conditions Problems to be dealt with because of exposure to air:

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Desiccation (drying out)

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Mobile organisms move in & out with tide

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Protective shells and/or mucus

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Store water efficiently

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Temperature (very warm temp)

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Organisms have a wide temperature range

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Light color of shell reflects light

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Salinity (concentration of salt)

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When it rains or snow melts, exposed plants and animals have to endure fresh water

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Must have a wide range of salinity tolerance

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Wave Action (mechanical effects that smash and tear away objects from substrates or to alter seafloor)

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Adaptations to maintain position include: becoming fixed to rocks (sessile), increasing thickness of shell, enlarging muscular foot

Vertical Zonation of Intertidal

Zonation is a vertical banding of the organisms living on the rocky coastline

The Supralittoral Zone

“

The Splash Zone

” 

Upper part of intertidal zone



Size of this zone depends on slope, splash, climate, and amount of shade

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Only covered briefly by water during the highest tides

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Dissolved nutrients and oxygen are limited

Black Lichen

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Black, tar-like blotches on rocks

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Symbiotic relationship of fungi and algae

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Fungi soaks up water like a sponge, storing it for long dry periods

Cyanobacteria



Blue-green algae

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Protected from desiccation by a jelly-like coating

Periwinkles

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Snail-like mollusks

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Abundant in intertidal

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Avoid desiccation by:

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clustering in moist, shady crevices.

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Sealing opening of shell

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Can breathe air

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Tolerate extreme temps.

Limpet

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Soft-bodied invertebrate protected by a hard, cone-like shell

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Cling tightly to rocks using muscular foot

Intertidal communities are separated by a process called Zoneation. Using zoneation we can identify four different zones; the upper, middle, lower, and sub-tidal zones. The upper inter tidal zone contains creatures like periwinkles, barnacles and limpets.

The middle intertidal zone supports more species of barnacles including gooseneck barnacles, as well as mussels and other sea animals.

The lower intertidal zone contains sea grasses, algae, and many of the sea animals that can be found in the intertidal community.

Upper Tidal Zone Middle Tidal Zone Lower Tidal Zone

The middle intertidal zone contains mussel colonies like the one seen here. Mussels are larger than Gooseneck barnacles, but similar in appearance. Mussels are also able to clamp down during periods of low tide, but because they are in a lower tidal zone, they are not exposed to desiccation as long as their counterparts in the upper intertidal zone. Mussels use strong hairs called bysal threads to attach themselves to rocks. Once there, they feed on microscopic plants filtered out of the sea water. They can grow anywhere from 3 inches up top 8 inches in length! Mussels are very good to eat, and work as a good fish bait as well.

Vertical Zonation of the Intertidal Upper Tidal Zone Middle Tidal Zone Lower Tidal Zone

Upper Intertidal Zone

 Harsh environment - exposed to rough waves during high tide and the hot sun during low tide  Includes same species as supralittoral (splash) zone

Striped Shore Crab

• Square Body • Eyes at corners • movie • Eat algae growing on the rocks by scraping with claws • Also prey on dead animals and live limpets & snails

Middle Intertidal

 Most active intertidal zone because it is fully covered and uncovered each day  Upper boundary is always marked by a band of acorn barnacles

Acorn Barnacle

 Attach firmly to substrate  Valve-like "doors" in shell that open when animal is submerged, and close when it is exposed to air  Feed on plankton by sucking in the water around them, while closing their teeth and opening their mouth. Then they lick all the plankton that are stuck in their teeth.

Ochre Sea Star

 Tiny suction cups called tube feet cover the underside of their five arms  Vicious predator of mussels  Extend stomach to externally digest food.  Regenerate body parts

California Mussel

 Large colonies on exposed rocks  Formation into dense clusters helps them retain moisture and lessens wave shock.   Feed by filtering plankton Provide shelter for smaller organisms Often considered a delicacy, mussels should not be eaten between the dates of May 1 and October 31. During this time mussels may filter and accumulate an extremely toxic plankton. Consuming mussels during this period can cause paralysis and death in humans.

Lower Intertidal Zone

 Dry only during lowest tides  Contains greatest biodiversity of intertidal zones

Gooseneck Barnacles

 Free-swimming larvae  Develop and attach to rocks  Long, neck-like stalk  Produce very strong adhesives  Use feathery feet to filter food from passing water  Live up to 20 years

Gooseneck Barnacles Limpet

Sunflower Star

 Major predator  The older they become, the more rays they grow. (up to 24 rays)  When threatened, these stars can drop an arm in hopes of appeasing the predator. The arm will later re-grow.