Marine Biology: Spatial and Temporal Scales

Chapter 10: Spatial and Temporal Scales

• Currents can transport organisms far from their origin because they do not flow in straight lines
• Eddies can carry organisms far from home
• During the day plankton are in deeper waters, and shallower waters at night, this is known as diurnal vertical migration
• Predation and lower metabolic cost in cooler water causes Diurnal vertical migration
• Bulk density, drag, swimming behavior, and turbulence influence the vertical position of plankton

Chapter 11: Phytoplankton Bloom Mechanisms

• The mechanisms of phytoplankton bloom and decline include light, mixing, nutrients, and predation
• Light intensity decreases with depth, different spectrum color ranges may be available at different depths.
• More sunlight results in more photosynthetic productivity up to a certain threshold
• Gross photosynthesis is the maximum photosynthesis an organism can do, including respiration
• Net photosynthesis is the difference between gross photosynthesis and respiration
• The compensation depth is the depth where oxygen consumed by a cell equals oxygen produced by photosynthesis
• At the compensation light intensity, depths greater result in less oxygen production than consumption
• Mixing happens because Colder water with higher density is heavier at the surface, which leads to overturn and turbulence in vertical mixing
• Plankton pushed below critical depth may lose photosynthetic abilities, leading to no bloom
• Critical depth is the depth above which total oxygen produced in the water column equals the total consumed
• A likely bloom will occur if mixing depth is less than critical depth
• No bloom will occur if mixing depth is greater than critical depth
• Mixing depth is the depth above which all water is thoroughly mixed due to wind
• A bloom occurs much later in the Arctic because the sun is available later
• In temperate regions, zooplankton rise and fall after the spring bloom
• Nutrients are scarce in tropical regions due to warm top water that prevents overturn and scarce deep water with nutrients which lowers phytoplankton bloom
• A spring bloom sometimes starts when the water column is still well mixed and water is cold, but maybe the bloom begins because light is increasing and grazing is low
• Sverdrup Models indicate that light is too low for phytoplankton growth, and mixing brings phytoplankton to average depths that preclude phytoplankton growth and bloom
• Phytoplankton decreasing to increasing is part of the Sverdrup Models
• Behrenfeld alternative model shows that autumn decrease in phytoplankton cell division, deepening of mixed layer reduction of grazing, early winter grazing pop is dilute and total increase but low, phytoplankton outstrips grazing in favorable light and nutrient condition

Nutrients In Marine Ecosystems

• New production relies on new nutrients
• Regeneration relies on recycled nutrients from excretion
• Nitrate is the most abundant source of nitrogen, nitrite does not last long, and ammonium ion is an excretion product
• Ammonium ion is taken up the fastest and is the most preferred, though has lower availability
• C:N:P in a ratio of 6:6:1 releases nutrients back into the water when phytoplankton die
• Bacteria within the microbial loop take up large amounts of nutrients, consumed by ciliates/heterotrophs, which are then consumed by smaller zooplankton
• Bacterially-derived nutrients becomes incorporated into the planktonic food web by zooplankton
• Nitrifying bacteria (oxic) converts NH4 to NO2, and other nitrifying bacteria converts NO2 to NO3
• Denitrifying bacteria (anoxic) converts NO3 to NH4 and ultimately returns NO3 to NO2
• Phosphorous occurs dissolved in water mainly as PO4
• Phosphorous is required for synthesis of ATP as a source of energy for cellular reactions
• HNLP means high nutrient low productivity
• Inshore species live in higher nutrient concentrations can be good at uptake at high concentrations
• Inshore species have a possible tradeoff and lower efficiency at low nutrient concentrations
• Open ocean species live in lower nutrient concentrations can be better at uptake at lower concentrations
• Open ocean species may not deal with higher concentrations

Chapter 12: Marine Productivity and Food Webs

• Biomass is the mass of living material at any time
• Biomass is expressed as grams per unit area or volume
• Productivity refers to the rate of production of living material per unit time per unit area or volume
• A food chain shows which organisms consume which other organisms in a linear sequence making a series of trophic levels
• A food web is a more complex diagram that showing feeding relationships among organisms not restricted to a linear hierarchy
• Transfer between trophic levels is not complete, some material not eaten and not all eaten is converted with 100% efficiency
• I(ingested) = E (egested) + R (respired) + G (growth)
• E = amount extracted from a trophic level/ amount of energy supplied to that level
• P (production at highest level) = B (primary production) E (efficiency) ^n(number of links between trophic levels)

Geographic Variations in Productivity

• Continental shelves and open-ocean upwelling are most productive
• Less trophic levels, rapid nutrient turnover, less complex structure, and high food chain efficiency exists because of high primary productivity
• Convergences and fronts often are sites of rise of nutrient-rich deep waters
• Central ocean and gyre centers are nutrient-poor and have low primary productivity
• Phytoplankton grow best on the innershelf, which has a nutrient-rich environment and is where runoff from land (nitrates and phosphates), shallower waters, and upwelling bring essential elements for growth
• Sunlight is an essential element for photosynthesis for phytoplankton to grow
• There is a limit to the number of links in a food chain due to significant energy loss
• It is unsustainable to support many levels, inherent structure, possible instability of large food chains with the risk of cascading extinction
• Gross primary productivity is the total carbon fixed during photosynthesis
• Net primary productivity is the total carbon fixed during photosynthesis minus that part which is respired

Marine Carbonate System

• Biological pumps are the solubility pump and phytoplankton
• The solubility pump involves colder/deeper water

Chapter 13: Benthic Microorganisms

• Bacteria are abundant in sediments and on surfaces
• Cyanobacteria occur in single cells to chains, N2 fixing, and often grow in mats where sediment is anoxic
• Diatoms grow as individual cells to chains of cells, cell wall full of silicon, abundant on soft sediments and rocks
• Fungi are eukaryotic, decomposing, disease organisms in sea grasses/marsh plants
• Regulation includes temperature, light, water flow, and oxygen transport
• Regulation also includes the avail, of nutrients, and organism matter (quality/quantity)
• Bacteria use light and chemicals to gain energy and then recycle nutrients

Benthic Algae Types

• Green algae is often shallow, has chlorophyll, and has no chemical defense but grows fast (sea lettuce)
• Brown algae consist of fucoxanthin, kelps, and are widespread
• Red algae has phycoerythrin and does not always look red
• Holdfast anchors plant to substrate
• Stipe is a stem-like feature attached to a holdfast
• Blades are photosynthetic organs
• Algae increase their total pigment concentration in deeper water since total light intensity decreases with depth and blue-green lights penetrate deeper
• Algae alter proportions of light harvesting pigments at different depths
• Seagrasses grow in very shallow water, are light limited, have very simple flowers, and pollen spreads on floating water
• Seagrasses have a rhizome system often with symbiotic N2 fixing bacteria within sediment
• Seagrasses grow through asexual growth and lateral spread, and shoots come out of the sediment spreading toward the surface

Chapter 3: Climate

• Climate refers to the features of the atmosphere and earth surfaces that relate to temperature, wind fields, and water movements
• Climate characteristics occur of large regions on the scale of years to centuries
• Climate change consists of longer-term trends superimposed on climate oscillations
• Oscillations exhibit predictable fluctuations of air pressure, wind fields, and moisture temperature on the scale of decades
• Trends are when climate properties change in the same direction often over centuries or millennia
• El Nino (southern oscillation) (ENSO) is shown with positive values and La Nina is shown with negative values
• Seabirds and other marine predators increase during non-El Nino years (strong upwelling)
• Seabirds and other marine predators decrease substantially during El Nino years (weak upwelling)
• The Pacific Decadal Oscillation (PDO) involves alternating periods of cool and warm water over 20-30 years
• Warm PDO periods allow great increases in salmon in Alaska, cool periods northern predators move southward and phytoplankton increases in bay

Chapter 14: Marine Life Classifications

• Cnidaria shows radial symmetry, with polyp and medusa stage, hydrozoa, scyphozoa (true jellyfish), and anthozoa (corals, anemones, sea whips)
• Annelida shows bilateral symmetry and is segmented, has muscles + gut + butt, polychaetes, oligochaetes, and leeches
• Pogonophora are gutless wonders from deep sea vent communities
• Mollusca includes bivalvia, gastropoda, bilateral symmetry, scales, chitons, and cephalopoda (octopods and cuttlefish)
• Arthropoda shows bilateral symmetry includes horseshoe crabs, crustacea (barnacles, lobsters), periodic molting, and jointed appendages
• Echinodermata are radial, usually 5-fold, have spiny skin, and include sea stars, sea cucumbers, and sea urchins.

Chapter 15: Soft Sediments

• Soft sediment involves a mixture of inorganic particles, organic particles, and pore water
• Particle size measures of current strength
• Sorting measures variation of current strength
• Silt-clay fraction shows percent of weight of sediment

Soft Sediment Microzone

• Displays strong vertical chemical gradients
• Use O2 to respire with aerobic bacteria
• Use RPD H2S oxidizing bacteria
• Use fermenting bacteria
• Use sulfate reducing bacteria to make hydrogen sulfide
• Use methanogenic bacteria with small organics creating methane
• Burrowers compress mud while sand does not
• Burrowing can be hydromechanical (combines muscle contraction working against skeleton, penetration anchor and terminal anchor) versus mechanically
• Burrowing impacts increases water content in sediment, increases grain size, and alters chemical and mechanical structures, delivers oxygen to sediments
• Benthic Feeding types include head down deposit feeders and surface browsers
• Head down deposit feeders transport fine particles to the surface
• Surface browsers are scavengers and feed on surface microorganisms
• Deposit feeders ingest sediment for nutrition from microalgae and POM

POM In Sediments

• Sinking phytoplankton, seaweeds, sea grasses, benthic phytos, feces, dead/live organisms
• Microbial stripping hypothesis shows deposit feeders are most efficient at digesting and assimilating benthic microbes (diatoms, bacteria)
• Juiciness increases from diatom -> seaweed -> seagrass
• Salt marsh grass is most complex, its chemical structure makes it hard to digest cellulose)
• Fecal pellets can be broken down and recolonized by microbes and some ingest own feces, inorganics and refractory material

Suspension Feeders

• Passive feeding involves extending a feeding organ into a current and collect particles like a sea pen
• There are issues of orientation in current, pressure drag, and saturation of feeding structure
• Active feeding involves creating a feeding current to uptake food like an acorn barnacle
• Active feeding can have issues, including saturation and clogging, selection of high quality particles, create current and keep siphon erect
• Carnivores include seastars and mantis shrimp with low pop size
• Movement to patches of prey, capture of prey, limitations, and feeding while avoiding predation relate to carnivores
• Microphages feed on microalgae like a parrot fish
• Macrophages feed on larger algaes like a sea urchin
• Mechanically attacking plants, chemical defenses of plants, and feeding while avoiding predation are issues that relate to macrophages
• Grazers are crucial for healthy coral reefs because they consume algae preventing overgrowth that can smother corals and limit their growth and space

Pacific Decadal Oscillation (PDO)

• Warm PDO has weaker upwelling in the eastern/central pacific, more sardines, less anchovies, deeper thermoclines, lower PP and lower nutrients, less salmon at CA and more at AK
• Cool PDO shows stronger upwelling in the eastern/central pacific, more anchovies, less sardines, shallower thermocline, and higher PP and higher nutrients