Ocean Biology

Biology Terms• Autotroph=“self feeder”, a plant,(producer)• Benthonic=Benthic-Benthos, bottom dwellers• Biomass= the gross weight of organisms in an area• Diversity= the number of species in an area• Epifauna= Benthos that are directly on the sea floor• Food chain/web= the order in which energy moves

through a community of living things• Habitat= an animal/plant’s “address” in the

environment• Heterotroph= animals/organisms that must get their

energy from eating other organisms (consumer)• Infauna= organisms living below sediment/water

interface

Biology Terms• Metazoans= multi-celled animals• Nekton= swimmers• Neritic=the area on or above continental shelf• Niche= exactly where an animal/plant fits into the

food chain (it’s profession)• Open ocean water- beyond the continental shelf• Pelagic= living in open ocean water• Plankton= extremely small nekton or forms

suspended in water column (at the mercy of ocean currents) zooplankton & phytoplankton

• Trophic= refers to food (trophic level)

The Biomass/Diversity Paradox

• In tropics- biomass low, diversity high

• In boreal waters (cool)- biomass high, diversity low

• Tropics are called “Noah’s ark” model

• Boreal waters are like a “stockyard”

• Biomass has direct relationship to latitude

• Diversity has inverse relationship to latitude

Trophic Systems-Boreal Waters(Low Diversity, high biomass,[stockyard])

• Tend to form complex trophic (food) webs • The loss of a single species is a disaster!• Most consumers have very loosely defined

niches• Opportunistic feeders “trophic slobs”• Considerable seasonal variation• Clumped distributions typical• Major fisheries located in boreal waters

Food Webs/Pyramids in Tropics(High Diversity, low biomass [Noah’s ark])

• Tend to form long, simple food chains before converging at top of pyramid

• Will stand the loss of several species without substantial harm to the community

• Most members have well defined niches• Highly specialized “trophic snobs” with

elaborate sexual isolation mechanisms• Dispersed distribution typical• Very little seasonal variation

Osmotic Regulation

• Marine organisms tend to lose water through the skin to the sea due to osmosis

• This is generally resolved by low urine production and constant drinking of water

• Fresh water taxa tend to adsorb water• The Osmosis problem is particularly tough

on coastal and estuarine animals where salinity is changing constantly with fluvial input and tides

Euphotic Zone=Photic Zone“aphotic zone”- deep water with no light

• “Maximum depth that light can penetrate water and support photosynthesis” (record is ~850’)

• Usually only 100’-200’• Can be raised or lowered by:

– Time of day or overcast sky– Angle of sun on horizon (season)– Turbidity of water– Storm conditions on surface– Biologic productivity (plankton bloom)

• Maximum euphotic depth would then be at high noon with sun directly overhead on the equator with cloudless sky & flat sea in a very unproductive area of ocean

Nocturnal/Diurnal Migration• All open ocean planktonic and nektonic

plants and animals descend in the water column during the day and rise to near the surface at night

• Plants migrate to acquire the right wavelength and intensity of sunlight for photosynthesis.

• Animals migrate simply to feed on the plants or on smaller animals that feed on plants.

• Deep scattering layer & military implications

Phytoplankton Blooms

• Almost uniform in the tropics (no seasons)• Two blooms in temperate latitudes but in

different months– Northern hemisphere (May & November)– Southern hemisphere (June & December)

• At boreal (high) latitudes one major bloom in North ~July & one in the South ~March

• Phytoplankton blooms are followed (by about a month) by zooplankton explosions

Lifestyles of the Rich and Famous

• Producers: make chlorophyll by photosythesis (plants),autotrophs

• Consumers: (animals), heterotrophs– Grazers:

• feed directly on plants

– Predators:• plankton feeders-can be very large or small• higher level predators: “lie in wait”, pursuit

(extremely sophisticated), top carnivores

Lifestyles of the Rich and Famous

• Filter feeders- must be in shallow, high energy but not turbid water

• Deposit feeders- ingest the sediment and pass it through GI tract (like earthworms)

• Detritus feeders- have the means to collect and separate & ingest detritus (the gelatinous partially decomposed organic “goo” lying on top of sediment

Lifestyles of the Rich and Famous

• Filter feeders- must be in shallow, high energy but not turbid water

• Deposit feeders- ingest the sediment and pass it through GI tract (like earthworms)

• Detritus feeders- have the means to collect and separate & ingest detritus (the gelatinous partially decomposed organic “goo” lying on top of sediment

Examples of Environmental Adaptations

• Teleost fish – “lungers, platys, cruisers”• Adaptations to soft substrates in deep water

– Snowshoe– Iceberg– Outrigger canoe– Tahitian house– HindenbergIn deep water, 4 major changes take place:1. Limited light – euphotic base ~100-200’2. No energy (stirring) of water and limited oxygen3. Water very cold-difficult to precipitate shell/skeleton4. Pycnocline as density layer is a tough floor for

plankton to penetrate and forms a base for biology

Adaptations by Fishes to Life in the Bathypelagic Realm

• Huge eyes and mouth• Only occasional feeding (like snakes)• Males may attach to females for life (SWEIN)• Bioluminescence as lure, species ID, schooling,

illuminate prey, and to elude predators.• Body not particularly well adapted for swimming (lie

in wait predators)• Body pigment (color) is grey to blue in shallow water,

but yellow, orange or red in very deep water.• Bottom dwellers may become detritus feeders.

The “Removal of the Middle Man” Strategy

• Where a group of animals moves back down the food chain several levels to avail themselves of the richer biomass there than higher up in the food chain..

– Examples:1. Baleen Whales2. Walrus feeding on molluscs3. Seals feeding on krill

“Success” in Biology

• Can be measured in diversity & biomass• Adaptive radiation (niche control)• Longetivity in the geologic record• Habitat controlBy these rules, three of the most successful

groups of organisms in the ocean are: • gastropod molluscs (snails)• marine arthropods (eg. crabs, shrimp, krill,

lobsters, copepods)• teleost (bony) fish

Images of Infrared & Biologic Productivity

• Infrared film is tuned so warm areas appear red and cold are in the blue/purple range– Infrared imaging easily defines upwelling/downwelling

& ocean currents

• Productivity maps in ordinary light show non-productive sterile water masses as cobalt blue and high nutrient, plant-rich water as pea green – By stretching the visible cobalt blue/pea-green

spectrum to a full spectrum we get red at the pea-green & purple at the deep blue

– Therefore areas of high productivity from cold upwelling would be blue on infrared film & red on the productivity film

Bioproductivitywhere nutrients, sunlight, and turbulence

meet• Highest is found

– In estuaries– At upwelling sites along coast– At high latitudes in cold water– Near sewer outfalls

• Lowest is found– Gyre centers– Along coasts with downwelling– At low latitudes in the warm water

• A flat, waveless sea quickly reaches stasis with minimal productivity due to a shallow wave base

Effects of Ekman Transport on Productivity

• Major Upwelling Zones – Ekman upwelling along coasts– Ekman upwelling along EEC

• Very low productivity in gyre centers due to Ekman downwelling of geostrophic flow

Biologic Productivity (generation of biomass) and Evolution

• In the ocean, productivity is related to availability of nutrients (N, P, Si, Zn, & Fe) and sunlight

• Is highest in estuaries & lowest in the middle of ocean gyres where Ekman spirals cause downwelling.

• Estuaries tend to have extremely high biomass but limited diversity (like boreal seas) because they are a highly stressed environment (large fluxuation of salinity & temperature).

• The geologic record suggests that evolution takes place in very shallow, high energy upper shelf water while extinctions take place at the edge of the continental shelf (walking the plank!)