Marine Oceanography: Circulation, Ecology, Pollution & Invasions

Discuss the physical properties that make water unique, how salts in seawater modify these properties, and how/why seawater stratifies

Water has high heat capacity and surface tension, is a universal solvent, and ice is denser than liquid water (density depends on the cluster effect, where increased temp decreases density, and thermal expansion, where decreased temp increases density). • Seawater has salt ions which disrupt the H-bonds. • Seawater usually doesn't freeze because salt ions disrupt the cluster effect; as it freezes it excludes salts, so the remaining saltwater becomes more concentrated. • Seawater stratifies due to salt wedge. [Your notes say "How???" - add the explanation: denser, saltier/colder water sits below lighter, fresher/warmer water.]

Describe/sketch the major ocean circulation in the deep (conveyor belt overturning circulation) and explain what drives the circulation (high latitude cooling and brine rejection)

Water sinks in the North Atlantic and around Antarctica. • Cold salty water is very dense (due to brine rejection during ice formation and rapid cooling). • The dense water sinks and the global deep circulation system transports new bottom water to all basins. • Oceans turn over on a global scale, about 1000 yr. Oldest deep water is in the Pacific. Surface return flow in the diagram is NOT representative of actual surface currents.

Describe/sketch the major ocean circulation in the surface (major ocean gyres) and explain what drives the circulation (winds and the Coriolis force)

Winds blowing parallel to the coast. • Coriolis force results in transport 90 degrees to the right, so winds push surface water away from the coast. • Surface water moving away from the coast is replaced by deeper water via upwelling. [Add: gyres are wind-driven + Coriolis.]

Describe/sketch typical coastal/estuarine circulation patterns

Salt wedge: freshwater flows out at the surface toward the estuary mouth, with a narrow, strict boundary between freshwater and the saltwater wedge below (almost no mixing, lots of fresh). Saltwater flows in along the bottom. • Mixing-zone estuary: freshwater outflow at surface, saltwater inflow at depth, mixing zone in between (good flow). • Estuaries are able to cycle nutrients from the deep water. Berms create a bump to prevent mixing. • Bad to dump waste into estuaries because circulation recycles pollutants.

Discuss the time scales of currents and mixing in the surface vs. the deep ocean

Deep waters take about 1000 years. • Surface waters take: [not filled in on your guide - add].

Discuss the requirements for photosynthesis (light and nutrients)

Photosynthesis needs energy (light), CO2 and water, as well as nutrients (N, P, Si, Fe, etc.).

Explain the concept of limiting nutrients and the Redfield ratio

The limiting nutrient controls how much product can be produced, because it limits the rest. • Redfield ratio: [not filled in on your guide - add (C:N:P = 106:16:1)].

Describe the vertical distribution of light and nutrients in the oceans

Light decreases exponentially with depth; at 1% light, photosynthesis is restricted. Water, dissolved organic compounds and particulate matter all absorb light energy. • Phytoplankton only photosynthesize in the surface layer (photic zone) and produce glucose, while respiration occurs at all depths. • There is a high concentration of N and P in the deep ocean.

Euphotic vs. aphotic zones

Euphotic zone: region of the water column where net photosynthesis is positive. • Aphotic zone: region of the water column where net photosynthesis is 0. There is a high concentration of N and P in the deep ocean.

Critical depth vs. compensation depth

Critical depth: depth in a mixing water column where P=R for the whole community (NCP=0). If MLD = CD then NCP=0. If MLD < CD then NCP>0, so biomass is positive. If MLD > CD then NCP<0, so biomass is negative. • Compensation depth: depth in the water column where P=R for a single organism/cell (typically the 1% light level).

Net community production vs. net photosynthesis

Net photosynthesis (NP) = gross photosynthesis - respiration. NP is the C that becomes part of the organism once we correct for respiration (AKA fixed carbon). During spring/summer NP >> respiration. • Net community production: [definition not filled in on your guide - add].

Mixed layer, pycnocline, halocline, thermocline

Mixed layer has the same temperature throughout (strong winds mix the water deeper). • Pycnocline / halocline / thermocline: [not filled in on your guide - add (zones of rapid change in density / salinity / temperature with depth)].

Describe food chain theory and food webs

Inorganic nutrients (phosphorus/nitrogen) → autotrophs (plants; create organic matter) = trophic level 1 → herbivores = TL2 → primary carnivores = TL3 → secondary carnivores = TL4. • Heterotrophs cannot produce organic matter (must consume it). • Only 10-20% of energy is transferred between trophic levels. • Food webs: [add].

Relate biomass to ecological pyramids

Biomass decreases at each trophic level going up (TL1 widest, TL4 narrowest). Only about 10% of biomass passes up to the next level; about 90% goes to decomposers.

Sketch the detrital food chain & microbial loop

Detrital food chain: Detritus (non-living organic C) → detritivore (bacteria, metazoans) = trophic level 1 → carnivore = trophic level 2. Each step creates biomass. • Microbial loop: [not filled in on your guide - add].

Define bioaccumulation & biomagnification

Bioaccumulation: when an organism excretes less pollutant than it takes in, so the majority of the pollutant dissolves in its fats and stays in the organism. • Biomagnification: order-of-magnitude increase of the pollutant at each trophic level.

Describe how ecosystem components can change seasonally (stability and complexity)

In the temperate zone in winter, MLD > CD because there is not enough light, so there are no algae blooms. In summer, MLD < CD and light is not limited, so there is a bloom, although resources start becoming limited.

Know the important/major sources of natural and anthropogenic discharges of oil to the marine environment; know the controls to these sources

Sources: shipping, effluent/atmosphere/drilling rigs, tanker disasters, and natural sources (marine seeps and sediment erosion). • Natural sources seep oil slowly and are distributed over a large area, so there is lots of room for dilution. Oil spills are a small area over a short period of time.

Discuss how the composition of oil determines its toxicology and behaviour in the marine environment

Crude oil is a mix of hydrocarbons. It can be converted to refined oil via fractional distillation (based on boiling point) and cracking (breaking long hydrocarbons). Refined oil is composed of only a small range of HCs with similar physical and chemical characteristics. • High MW HCs: coating/smothering effects, less toxic but more persistent. • Small HCs: most toxic but volatile and short-lived. • If HCs are ingested they are incorporated into lipids (more complex HCs are more toxic).

Know the weathering processes (long- and short-term) of oil in the marine environment

Short term: spreading (wind spreads it), dissolution. • Long term: dispersion; emulsion (integration of droplets into the water column depends on turbulence from wind; without wind it floats because oil is less dense than water); evaporation (temperature affects evaporation).

Correctives: Know the methods/processes of prevention and cleanup (long- and short-term) of accidental oil input

Prevention: personnel, ship maintenance/retiring old ships, cargo hold segregation/ballasting (filled with water). • Cleanup: offloading (reduces volume of spill), burning, chemical dispersal via detergents (inhibits evaporation and increases dissolution), mechanical containment via booms, pumps/skimmers/collectors (difficult in poor weather), sinking by adding sand, bioremediation (good but slow; uses microbes).

Discuss how an oil spill affects a marine ecosystem over the long- and short-term

Short term (days to weeks/months): direct acute toxicity, smothering (oil envelops organism so it cannot eat/breathe), shading (covers surface so no light), food chain effects, biochemical oxygen demand. • Long term (years to decades/intergenerational): direct chronic toxicity, intergenerational effects, food chain effects, differential toxicity to life stages, compaction of sediments (oil at the bottom prevents sediments from interacting with the water column above).

Describe how sound propagates in ocean

In shallow water, propagating noise interacts repeatedly with the water surface and seafloor. • In deep water, directionality is dipolar (downwards), with low interaction with seafloor and surface. • Noise can be trapped/coupled in the SOFAR channel, where it bounces.

List and describe sources of noise pollution

Fishing, transportation, underwater mining/dredging, oil and gas drilling, ocean studies, ship traffic, earthquakes. The strongest source is the propeller.

Discuss the effects of sound on marine mammals

Stress; behavioural/acoustic response (echolocation); temporary/permanent shifts in hearing thresholds; auditory masking (threshold of hearing for one sound is raised by the presence of another).

Discuss possible corrective measures to reduce the effects of marine noise

Research/monitoring; education/awareness to propagate best practices; noise reduction measures (voluntary speed reduction programs, changing shipping patterns, promoting development/use of new quieter ships).

Describe the sources of industrial thermal pollution to the marine environment

Electrical power plants, refineries, petrochemical plants, steel mills, paper and pulp mills.

Describe the characteristics of industrial cooling systems

Water goes into the condenser to cool and comes out as hot water.

Describe the toxic effects of effluent waters on biota

Effluent water is hotter than the receiving water body. • Thermal effects (motile organisms can avoid temperature changes if the area is small or the change slow; sessile organisms are very susceptible). • Straining/pressure effects, chlorination effects, and gas bubble disease. • Temperature increase but O2 depleted, which stresses aerobic organisms. • Changes in reproduction.

Define Biological pollution, Invasive species, Exotic species, Naturalized species

Exotic species: a species introduced from the geographic region where it evolved to an area outside its natural range. • Naturalized species: exotic species that are able to reproduce in the new environment. • Invasive species: naturalized exotic species that spread in the new environment and cause economic, health or ecosystem harm. • Biological pollution: [not filled in on your guide - add].

Identify possible vectors and pathways for invasions in a given area

Changing climate conditions; extreme weather events; removal of barriers (increased globalization); hitchhiking with migratory animals; shipping/boating (ballast water, sediment may store organisms, and hull fouling where sessile/sedentary organisms attach to the ship and spawn on arrival); aquaculture trade; research/teaching.

List and describe possible/existing impacts of given species on the ecosystem

Environmental (resource competition, predation, biodiversity loss, altered ecosystems); economic (cost of handling the invasion); social; human health (e.g., cholera).

Propose effective management strategies for given case of invasion in accordance to environmental conditions and biological specifications

Biotic resistance: species-rich communities may be more resistant to invasion (limited resources, more predators). • Environmental conditions: stenotopic species are bad invaders. • Prevention: best method and least costly; predict invasions based on source invasion hot spots. • Control (mechanical/chemical/biological): time consuming and costly. • Eradication: difficult and costly because of open water.

Required readings: Discuss the trends of the spread of the invasions

High environmental connectivity through the water medium fosters the dispersal of species.

Required readings: Which pathways are most common, which species?

[not filled in on your guide - add]

Required readings: What are the preferred actions that are applied to manage invasions?

Raising public awareness is most applicable to control. Doing nothing was ranked highest because it was least expensive and most accessible.

Elective reading (Styela clava): Species name

Styela clava

Elective reading (Styela clava): Origin

North-west Pacific

Elective reading (Styela clava): Region/regions of invasion

New Zealand

Elective reading (Styela clava): Time of invasion

2002

Elective reading (Styela clava): Biological characteristics of species that allow it to invade

Hermaphrodite with highly seasonal reproductive cycles; spawns when sea temperatures are well above the critical threshold (reproduction associated with seawater above 15°C) and photoperiod may also trigger spawning. • Reproduction periods last 4-10 months; maximum in February, lowest in fall. • Testes development is slightly ahead of ovaries (protandric hermaphroditism).

Elective reading (Styela clava): Invasion management

Research on reproductive biology for post-border biosecurity management. • Prevent further spread (boating and aquaculture spread gametes and larvae). • Hand removal at the base of the stalk (prevents more gamete spread). • Wrapping in plastic for 1 week induces death. • Do removal from late June to early September, before sea temps reach 16°C (before ripe gametes exist), and before sunrise (photoperiod can trigger spawning). • Marina post-border eradication completed in 2008: divers hand-removed about 10,000 individuals.

Elective reading (Styela clava): Predictions on development of invasion and management success

Further spread across New Zealand appears imminent because of the long reproductive season. • Larvae/gametes spread via boating and aquaculture (domestic hull fouling between Australia and NZ; transport of aquaculture material, flotsam, kelp rafting). • Rising seawater temperature can extend the reproductive season. • New marinas colonize quickly (Okahu Bay, Auckland, colonized within months of opening in 2006). • Hand removal is often unsuccessful, giving more time to reproduce and establish.

Explain the importance of salmon for terrestrial ecosystems

Many organisms rely on marine-derived nitrate, which comes from salmon.

Identify the differences between farmed salmon and wild salmon species in B.C.

Farmed salmon: born and raised in captivity. • Wild salmon: spawn and are born in fresh water, and return to it after foraging at sea.

Salmon farming pollution: organic pollution (feces, unconsumed food, processing wastes)

Causes anoxic conditions in seabed sediments and release of methane, hydrogen and N2 gas; nutrient (N/P) loading causes eutrophication. • Solution: move farms every couple of months so sediments can dilute the waste.

Salmon farming pollution: chemical pollution (antibiotics, pesticides, antifouling paints)

Antibiotics persist because marine sediments act as a long-term reservoir, affecting marine communities (antibiotic resistance). • Pesticides may be at concentrations lethal to some species. • Copper and zinc in paints can be harmful to different organisms.

Salmon farming pollution: biological pollution (diseases, particularly sea lice, escapes)

Exotic diseases/parasites may be brought in with imported fish eggs. • Sea lice are associated with salmon farms and may infect wild species passing by. • Escaped salmon can spread disease/parasites, predate on/compete with wild species, and establish exotic populations. • Solution: improve farms and management.

Discuss the risks to wild salmon populations and to fish predators from salmon farming

Farmed salmon may be bigger and stronger competitors. • Solution: use triploid salmon so they cannot reproduce.

Distinguish between open net and closed system farming

Open net: in the ocean. • Closed system: completely separates wild and farmed salmon, giving lower cost and lower death rates.

Be aware of current legislation regarding salmon farming in B.C.

By 2029, total ban on open net salmon aquaculture.

Discuss input types, sources and pathways of marine plastics/microplastics

Primary microplastics: plastic powders used in molding, microbeads (cosmetics), plastic nanoparticles for industrial processes. • Secondary microplastics: result from the use of products (textiles, tires) and from environmental breakdown. • Pathways: riverine input, coastal dump sites, shore-based industries, coastal recreation, recreational boating, shipping/fishing, wastewater treatment plants, storm water runoff.

Describe the fate of plastics in the ocean: residence time, degradation/fragmentation, changes with time

Most plastics are non-biodegradable and break down slowly through mechanical/photo-oxidation. • Microplastics are the by-product of degradation and fragmentation. • Much plastic takes 100s of years to decompose. • Much plastic sinks and forms sediment via marine snow and fecal pellets.

Discuss the effect of sizes (mega, macro, meso, micro) and density on the fate of plastics

[not filled in on your guide - add]

Interactions between marine biota and plastics: Why do organisms ingest plastics? Effects of ingestion

Raw plastic pellets resemble zooplankton food/eggs, so they are likely to be ingested. • Direct effects: starvation, blocked digestive system, suffocation.

Interactions between marine biota and plastics: "Ghost fishing"

Lost/abandoned gill/trawl nets and crab/lobster traps keep floating and catching animals, which eventually die.

Interactions between marine biota and plastics: Role of plastics in dispersal of exotic/invasive species

[not filled in on your guide - add]

Interactions between marine biota and plastics: Toxins released from plastics

[not filled in on your guide - add]

Interactions between marine biota and plastics: Effects on human health

Many microplastics may be in the foods that we eat.

Discuss plastic recycling and biodegradation alternatives

Recycling saves energy, burns fewer fossil fuels, and reduces CO2 and other GHG emissions. • Mechanical recycling: no change to the molecular framework, only physical transformation. • Chemical recycling: depolymerizes then reconverts; challenges are high cost and the need for high heat/pressure and chemical agents.

Differentiate between bioplastics and "biodegradable" plastics

Bioplastic: made from renewable source materials and is biodegradable. • "Biodegradable" plastic: [add contrast - not filled in on your guide].

Discuss barriers to solutions to the plastic problem

Barriers are technology (recycling, degradable plastics) and education (clean-up of marine debris, zero waste strategy).