Divemaster exam A - chapters 1-8 Flashcards
what are two ocean resources vital to life?
1) oxygen
- from ocean phytoplankton and cyanobacteria
2) heat distribution
- ocean’s ability to absorb, carry and release heat
Primary producers
organisms that get their energy from sunlight = converting sunlight energy into energy-containing compounds
- the base of all food chains
photosynthesis
the process by which plants/primary producers convert CO2 and water into oxygen and carbs
Highly productive ocean areas
areas with coastal upwellings = nutrients
EG: Polar regions
Mangrove ecosystem services (2)
1) trap excess nutrients, pollutants and sediments
2) habitat for invertebrates and juvenile reef fish
Threats to mangroves (4)
1) real estate
2) dredging
3) aquaculture
4) chemicals
example of organic waste? (2)
- agriculture runoff
- red tides
cause of red tides?
nutrient pollution/algae overgrowth
solid wastes
heavy metals, toxic chemicals, oil accumulate in sediment
forces that cause currents (4)
1) surface winds
2) earth’s rotation
(deflect R. in Northern hemisphere, L. in Southern Hemisphere)
3) winds
4) weather
best time to dive based on tides
high tide or slack tide
three types of breaking waves
1) plunging breakers - moderately steep beaches
2) spilling breakers - gently sloping beaches
3) surging breakers - very steep beaches
what is a rip current?
A local current that occurs when waves push water over a long obstruction (sandbar or reef)
Primary productivity
a process by which energy enters the food chain by primary producers
% of water on Earth
71%
% of water that is Seawater?
97%
Why dive in an environmentally responsible manner? (4)
- You don’t want to harm aquatic life
- Role modeling environmentally responsible diving is in the PADI Member’s Code of Practice
- Kicking and bumping into aquatic life causes major damage.
- Directly encouraging other divers to reduce their effect on the environment
- Divers have a growing collective voice that can influence environmental initiatives and policies that affect the underwater world - to be credible as environmental ambassadors, we must show that we practice what we preach.
Diving in an environmentally responsible manner is important because:
You are a role model to others and should be a passionate ambassador
What ultimately connects all the water on Earth?
The hydrological cycle connects all water (inland and underground bodies).
What is the base of the marine food chain?
Primary producers - photosynthesis by phytoplankton, which need sunlight AND nutrients
why are some areas much more productive than others?
Areas (continental shelves, polar regions) that have costal upwellings (water flowing up from the deep) tend to be highly productive because upwellings bring nutrients to the surface.
Open ocean has little primary productivity due to lack of nutrients, ocean bottom has ample nutrients but sunlight doesn’t penetrate that far - except in areas with thermal vents where chemosynthesizers form small ecosystems by converting inorganic chemical energy into useable carbohydrates.
Why are coral reefs important?
Most productive, complex, and diverse ecosystems on Earth.
what benefits do coral reefs provide?
- Corals are primary producers
(symbiotic phytoplankton live in them)
- incredibly efficient at recycling available nutrients and the nutrient-free water protects coral from organisms from organisms that would compete/cloud water and block sunlight. - Nursery grounds for 25% of all known marine species, home to about 33% of all known fish species.
- Form extensive reef structures that protect island and coastal communities from storms, wave damage, and erosion by forming massive barrier reefs.
- Increasingly important to commerce and regional economies, tourism relies on the appeal of their coral reefs, pharmacologists find biomedical compounds such as antibiotics and anti-cancer agents.
What are the major threats to coral reefs?
Human activities
- Land clearing (choking polyps)
- Fishing practices (destroying coral structures)
Global warming (climate change)
what contributes to the destruction of wetlands?
- Human-induced damage - primary threat
(Mangroves and estuaries have been dredged out to make harbors, or filled in for housing development, destroyed by conversion to aquaculture farms)
Why are wetlands important?
Vital to all other aquatic environments, crucial for the ocean’s ecological health and production of fish used as a human food source.
Why are marine fisheries near collapse, and how do you support sustainable fisheries?
Industrial fishing has such high demands to the point that ocean fish catches have become unsustainable.
- Fish populations have declined as improving tech allow catch levels to be high
(Overfishing)
- Overfished species don’t reproduce fast enough to
sustain commercial fishing and population recovery
takes decades, if at all - Pollution/habitat destruction
We can support sustainable fisheries by:
- Being a selective buyer.
- Support the establishment of Marine Protected Areas (MPAs) they encompass wide range of marine areas that restrict human activity to protect living, non-living, cultural and/or historic resources.
What effects do organic matter, solid wastes, oils, chemicals, plastics and heat effluent have on the aquatic environment?
- Organic waste:
runoff from agriculture - Human sewage:
organic waste but doesn’t cause plankton blooms - Solid wastes:
(Heavy metals, toxic chemicals, oil) - Oils:
self explanatory - Plastics:
self-explanatory - Heat effluent:
heat pollution enters primarily though released cooling water from coast power stations/facilities
Biomagnification: Heavy metals, pesticides, other toxins that don’t break down readily and accumulate
*Animals low on the food chain have trace amounts, eaten by higher consumers they accumulate to levels that cause birth defects, disease, reproductive issues
What are eight precautions to reduce the likelihood of being injured by an aquatic animal?
- Treat all animals with respect - don’t tease/intentionally disturb/dive unobtrusively
- Be cautious in extremely murky water - watch hand placement/potentially aggressive animals can mistake you as prey and avoid diving if they may be present
- Don’t wear shiny, dangly jewelry - resemble bait fish or small prey/attracts interests of predators
- Wear gloves and an exposure suit to avoid stings or cuts - be especially cautious of what you touch
- Maintain neutral buoyancy - stay off bottom
- Move slowly and carefully
- Watch where you’re going and where you put your hands, feet and knees
- Avoid contact with unfamiliar organisms - general rule is if an animal is very pretty or very ugly and doesn’t flee, don’t touch it, these are common characteristics of a venomous species