Ocean Biology Biology Terms

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

Examples of Environmental Adaptations • • Teleost fish – “lungers, platys, cruisers” Adaptations to soft substrates in deep water – – – Snowshoe Iceberg Outrigger canoe Tahitian house Hindenberg In deep water, 4 major changes take place: 1. 2. 3. 4. Limited light – euphotic base ~100 -200’ No energy (stirring) of water and limited oxygen Water very cold-difficult to precipitate shell/skeleton 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. . – 1. 2. 3. Examples: Baleen Whales Walrus feeding on molluscs Seals feeding on krill

“Success” in Biology • Can be measured in diversity & biomass • Adaptive radiation (niche control) • Longetivity in the geologic record • Habitat control By 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 nonproductive 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 peagreen & purple at the deep blue – Therefore areas of high productivity from cold upwelling would be blue on infrared film & red on the productivity film

Bioproductivity where 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!)