QCAA Marine Science EA cheat sheet

Seawater density rises with increasing salinity and decreasing temperature; density is maximal near 4 °C for fresh water but continues to increase as seawater cools toward its freezing point.

Salinity is the total mass of dissolved salts per kilogram of seawater, expressed in practical salinity units; the global mean is about 35.

Thermocline: layer of rapid temperature decrease with depth; halocline: rapid salinity change; pycnocline: rapid density change, which suppresses vertical mixing.

Coriolis effect deflects moving water and air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; magnitude scales with latitude and speed.

Geostrophic balance: horizontal pressure-gradient force balanced by Coriolis force, producing large-scale surface currents such as western boundary currents.

Ekman transport moves net surface-layer transport 90° to the right of wind direction in the Northern Hemisphere, driving coastal upwelling when winds blow parallel to shore with the coast on the left.

Spring tides occur at new and full moon when solar and lunar tidal forces align; neap tides occur at quarter moons when they oppose.

Wave refraction concentrates energy on headlands and disperses it in bays; longshore drift moves sediment in the direction of the dominant oblique wave approach.

Thermohaline circulation is driven by density differences from temperature and salinity; cold, salty water sinks in high-latitude regions and drives deep-ocean overturning.

Population growth: exponential model dN/dt = rN; logistic model dN/dt = rN(K − N)/K, where K is carrying capacity and r is intrinsic growth rate.

Primary productivity is limited by light, nutrients (nitrogen, phosphorus, iron), temperature and grazing; iron limits productivity in large high-nutrient, low-chlorophyll regions.

Trophic levels transfer roughly 10% of energy upward; biomass pyramids can invert in systems dominated by high-turnover producers, but energy pyramids cannot.

Keystone species exert disproportionate influence on community structure relative to abundance; removal triggers cascading change.

Ecological succession on rocky shores proceeds from pioneer colonisers to more competitive species, with disturbance resetting the sequence.

Biodiversity indices: species richness counts species; Shannon index H = −Σ pᵢ ln pᵢ weights evenness as well as richness.

Symbiosis types: mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, host harmed).

Estuaries and mangroves act as nursery habitats, nutrient traps and coastal buffers; seagrass meadows stabilise sediment and sequester carbon.

Coral bleaching occurs when thermal stress causes loss of symbiotic zooxanthellae; recovery depends on duration and intensity of the stress event.

Maximum sustainable yield (MSY) occurs near half the unfished carrying capacity in the logistic model; fishing beyond this point reduces sustainable catch.

Maximum economic yield occurs at a lower effort than MSY because it accounts for costs; open-access fisheries tend toward overexploitation (tragedy of the commons).

Fishery management tools include catch quotas, effort limits, size limits, closed seasons, marine protected areas and individual transferable quotas.

Marine protected areas are most effective when large, well-enforced, no-take and connected by larval dispersal; spillover can benefit adjacent fisheries.

Bycatch reduction devices, turtle excluder devices and gear restrictions reduce non-target mortality; observer programs and logbooks supply verification data.

Aquaculture can relieve wild-stock pressure but introduces risks: nutrient loading, escapees, disease transfer and reliance on wild-caught feed fish.

Tourism impacts include anchor damage, trampling, wildlife disturbance and wastewater discharge; carrying capacity and zoning limit cumulative effects.

Eutrophication sequence: nutrient enrichment → algal bloom → decomposition → oxygen depletion → hypoxia and dead zones.

Management follows adaptive cycles of monitoring, assessment, regulation and review; integrated coastal zone management coordinates competing uses across jurisdictions.

Validity: the investigation measures what it claims; controlled variables held constant, appropriate control group, and only the independent variable changed.

Reliability: consistency of repeated measurements; increased by replicates, standardised technique and calibration of instruments.

Accuracy: closeness to the true value; precision: closeness of repeated measurements to each other; random error affects precision, systematic error affects accuracy.

Uncertainty of repeated measurements is commonly reported as standard deviation; uncertainty of a single reading is typically half the smallest scale division.

Hypothesis must be testable and falsifiable; a prediction states the expected direction of change in the dependent variable.

Transect and quadrat sampling estimate abundance and distribution; random placement avoids bias, and percentage cover suits sessile organisms.

Mark-recapture abundance estimate: N = (M × C)/R, where M is marked, C is total in second sample and R is recaptures.

Correlation does not establish causation; confounding variables and sampling bias must be evaluated before inferring cause.

Evaluate evidence by checking sample size, replication, control of variables, statistical significance, and whether conclusions exceed the data.

Seawater density rises with increasing salinity and decreasing temperature; density is maximal near 4 °C for fresh water but continues to increase as seawater cools toward its freezing point.

Salinity is the total mass of dissolved salts per kilogram of seawater, expressed in practical salinity units; the global mean is about 35.

Thermocline: layer of rapid temperature decrease with depth; halocline: rapid salinity change; pycnocline: rapid density change, which suppresses vertical mixing.

Coriolis effect deflects moving water and air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; magnitude scales with latitude and speed.

Geostrophic balance: horizontal pressure-gradient force balanced by Coriolis force, producing large-scale surface currents such as western boundary currents.

Ekman transport moves net surface-layer transport 90° to the right of wind direction in the Northern Hemisphere, driving coastal upwelling when winds blow parallel to shore with the coast on the left.

Spring tides occur at new and full moon when solar and lunar tidal forces align; neap tides occur at quarter moons when they oppose.

Wave refraction concentrates energy on headlands and disperses it in bays; longshore drift moves sediment in the direction of the dominant oblique wave approach.

Thermohaline circulation is driven by density differences from temperature and salinity; cold, salty water sinks in high-latitude regions and drives deep-ocean overturning.

Population growth: exponential model dN/dt = rN; logistic model dN/dt = rN(K − N)/K, where K is carrying capacity and r is intrinsic growth rate.

Primary productivity is limited by light, nutrients (nitrogen, phosphorus, iron), temperature and grazing; iron limits productivity in large high-nutrient, low-chlorophyll regions.

Trophic levels transfer roughly 10% of energy upward; biomass pyramids can invert in systems dominated by high-turnover producers, but energy pyramids cannot.

Keystone species exert disproportionate influence on community structure relative to abundance; removal triggers cascading change.

Ecological succession on rocky shores proceeds from pioneer colonisers to more competitive species, with disturbance resetting the sequence.

Biodiversity indices: species richness counts species; Shannon index H = −Σ pᵢ ln pᵢ weights evenness as well as richness.

Symbiosis types: mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, host harmed).

Estuaries and mangroves act as nursery habitats, nutrient traps and coastal buffers; seagrass meadows stabilise sediment and sequester carbon.

Coral bleaching occurs when thermal stress causes loss of symbiotic zooxanthellae; recovery depends on duration and intensity of the stress event.

Maximum sustainable yield (MSY) occurs near half the unfished carrying capacity in the logistic model; fishing beyond this point reduces sustainable catch.

Maximum economic yield occurs at a lower effort than MSY because it accounts for costs; open-access fisheries tend toward overexploitation (tragedy of the commons).

Fishery management tools include catch quotas, effort limits, size limits, closed seasons, marine protected areas and individual transferable quotas.

Marine protected areas are most effective when large, well-enforced, no-take and connected by larval dispersal; spillover can benefit adjacent fisheries.

Bycatch reduction devices, turtle excluder devices and gear restrictions reduce non-target mortality; observer programs and logbooks supply verification data.

Aquaculture can relieve wild-stock pressure but introduces risks: nutrient loading, escapees, disease transfer and reliance on wild-caught feed fish.

Tourism impacts include anchor damage, trampling, wildlife disturbance and wastewater discharge; carrying capacity and zoning limit cumulative effects.

Eutrophication sequence: nutrient enrichment → algal bloom → decomposition → oxygen depletion → hypoxia and dead zones.

Management follows adaptive cycles of monitoring, assessment, regulation and review; integrated coastal zone management coordinates competing uses across jurisdictions.

Validity: the investigation measures what it claims; controlled variables held constant, appropriate control group, and only the independent variable changed.

Reliability: consistency of repeated measurements; increased by replicates, standardised technique and calibration of instruments.

Accuracy: closeness to the true value; precision: closeness of repeated measurements to each other; random error affects precision, systematic error affects accuracy.

Uncertainty of repeated measurements is commonly reported as standard deviation; uncertainty of a single reading is typically half the smallest scale division.

Hypothesis must be testable and falsifiable; a prediction states the expected direction of change in the dependent variable.

Transect and quadrat sampling estimate abundance and distribution; random placement avoids bias, and percentage cover suits sessile organisms.

Mark-recapture abundance estimate: N = (M × C)/R, where M is marked, C is total in second sample and R is recaptures.

Correlation does not establish causation; confounding variables and sampling bias must be evaluated before inferring cause.

Evaluate evidence by checking sample size, replication, control of variables, statistical significance, and whether conclusions exceed the data.

Seawater density rises with increasing salinity and decreasing temperature; density is maximal near 4 °C for fresh water but continues to increase as seawater cools toward its freezing point.

Salinity is the total mass of dissolved salts per kilogram of seawater, expressed in practical salinity units; the global mean is about 35.

Thermocline: layer of rapid temperature decrease with depth; halocline: rapid salinity change; pycnocline: rapid density change, which suppresses vertical mixing.

Coriolis effect deflects moving water and air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; magnitude scales with latitude and speed.

Geostrophic balance: horizontal pressure-gradient force balanced by Coriolis force, producing large-scale surface currents such as western boundary currents.

Ekman transport moves net surface-layer transport 90° to the right of wind direction in the Northern Hemisphere, driving coastal upwelling when winds blow parallel to shore with the coast on the left.

Spring tides occur at new and full moon when solar and lunar tidal forces align; neap tides occur at quarter moons when they oppose.

Wave refraction concentrates energy on headlands and disperses it in bays; longshore drift moves sediment in the direction of the dominant oblique wave approach.

Thermohaline circulation is driven by density differences from temperature and salinity; cold, salty water sinks in high-latitude regions and drives deep-ocean overturning.

Population growth: exponential model dN/dt = rN; logistic model dN/dt = rN(K − N)/K, where K is carrying capacity and r is intrinsic growth rate.

Primary productivity is limited by light, nutrients (nitrogen, phosphorus, iron), temperature and grazing; iron limits productivity in large high-nutrient, low-chlorophyll regions.

Trophic levels transfer roughly 10% of energy upward; biomass pyramids can invert in systems dominated by high-turnover producers, but energy pyramids cannot.

Keystone species exert disproportionate influence on community structure relative to abundance; removal triggers cascading change.

Ecological succession on rocky shores proceeds from pioneer colonisers to more competitive species, with disturbance resetting the sequence.

Biodiversity indices: species richness counts species; Shannon index H = −Σ pᵢ ln pᵢ weights evenness as well as richness.

Symbiosis types: mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, host harmed).

Estuaries and mangroves act as nursery habitats, nutrient traps and coastal buffers; seagrass meadows stabilise sediment and sequester carbon.

Coral bleaching occurs when thermal stress causes loss of symbiotic zooxanthellae; recovery depends on duration and intensity of the stress event.

Maximum sustainable yield (MSY) occurs near half the unfished carrying capacity in the logistic model; fishing beyond this point reduces sustainable catch.

Maximum economic yield occurs at a lower effort than MSY because it accounts for costs; open-access fisheries tend toward overexploitation (tragedy of the commons).

Fishery management tools include catch quotas, effort limits, size limits, closed seasons, marine protected areas and individual transferable quotas.

Marine protected areas are most effective when large, well-enforced, no-take and connected by larval dispersal; spillover can benefit adjacent fisheries.

Bycatch reduction devices, turtle excluder devices and gear restrictions reduce non-target mortality; observer programs and logbooks supply verification data.

Aquaculture can relieve wild-stock pressure but introduces risks: nutrient loading, escapees, disease transfer and reliance on wild-caught feed fish.

Tourism impacts include anchor damage, trampling, wildlife disturbance and wastewater discharge; carrying capacity and zoning limit cumulative effects.

Eutrophication sequence: nutrient enrichment → algal bloom → decomposition → oxygen depletion → hypoxia and dead zones.

Management follows adaptive cycles of monitoring, assessment, regulation and review; integrated coastal zone management coordinates competing uses across jurisdictions.

Validity: the investigation measures what it claims; controlled variables held constant, appropriate control group, and only the independent variable changed.

Reliability: consistency of repeated measurements; increased by replicates, standardised technique and calibration of instruments.

Accuracy: closeness to the true value; precision: closeness of repeated measurements to each other; random error affects precision, systematic error affects accuracy.

Uncertainty of repeated measurements is commonly reported as standard deviation; uncertainty of a single reading is typically half the smallest scale division.

Hypothesis must be testable and falsifiable; a prediction states the expected direction of change in the dependent variable.

Transect and quadrat sampling estimate abundance and distribution; random placement avoids bias, and percentage cover suits sessile organisms.

Mark-recapture abundance estimate: N = (M × C)/R, where M is marked, C is total in second sample and R is recaptures.

Correlation does not establish causation; confounding variables and sampling bias must be evaluated before inferring cause.

Evaluate evidence by checking sample size, replication, control of variables, statistical significance, and whether conclusions exceed the data.

Seawater density rises with increasing salinity and decreasing temperature; density is maximal near 4 °C for fresh water but continues to increase as seawater cools toward its freezing point.

Salinity is the total mass of dissolved salts per kilogram of seawater, expressed in practical salinity units; the global mean is about 35.

Thermocline: layer of rapid temperature decrease with depth; halocline: rapid salinity change; pycnocline: rapid density change, which suppresses vertical mixing.

Coriolis effect deflects moving water and air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere; magnitude scales with latitude and speed.

Geostrophic balance: horizontal pressure-gradient force balanced by Coriolis force, producing large-scale surface currents such as western boundary currents.

Ekman transport moves net surface-layer transport 90° to the right of wind direction in the Northern Hemisphere, driving coastal upwelling when winds blow parallel to shore with the coast on the left.

Spring tides occur at new and full moon when solar and lunar tidal forces align; neap tides occur at quarter moons when they oppose.

Wave refraction concentrates energy on headlands and disperses it in bays; longshore drift moves sediment in the direction of the dominant oblique wave approach.

Thermohaline circulation is driven by density differences from temperature and salinity; cold, salty water sinks in high-latitude regions and drives deep-ocean overturning.

Population growth: exponential model dN/dt = rN; logistic model dN/dt = rN(K − N)/K, where K is carrying capacity and r is intrinsic growth rate.

Primary productivity is limited by light, nutrients (nitrogen, phosphorus, iron), temperature and grazing; iron limits productivity in large high-nutrient, low-chlorophyll regions.

Trophic levels transfer roughly 10% of energy upward; biomass pyramids can invert in systems dominated by high-turnover producers, but energy pyramids cannot.

Keystone species exert disproportionate influence on community structure relative to abundance; removal triggers cascading change.

Ecological succession on rocky shores proceeds from pioneer colonisers to more competitive species, with disturbance resetting the sequence.

Biodiversity indices: species richness counts species; Shannon index H = −Σ pᵢ ln pᵢ weights evenness as well as richness.

Symbiosis types: mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, host harmed).

Estuaries and mangroves act as nursery habitats, nutrient traps and coastal buffers; seagrass meadows stabilise sediment and sequester carbon.

Coral bleaching occurs when thermal stress causes loss of symbiotic zooxanthellae; recovery depends on duration and intensity of the stress event.

Maximum sustainable yield (MSY) occurs near half the unfished carrying capacity in the logistic model; fishing beyond this point reduces sustainable catch.

Maximum economic yield occurs at a lower effort than MSY because it accounts for costs; open-access fisheries tend toward overexploitation (tragedy of the commons).

Fishery management tools include catch quotas, effort limits, size limits, closed seasons, marine protected areas and individual transferable quotas.

Marine protected areas are most effective when large, well-enforced, no-take and connected by larval dispersal; spillover can benefit adjacent fisheries.

Bycatch reduction devices, turtle excluder devices and gear restrictions reduce non-target mortality; observer programs and logbooks supply verification data.

Aquaculture can relieve wild-stock pressure but introduces risks: nutrient loading, escapees, disease transfer and reliance on wild-caught feed fish.

Tourism impacts include anchor damage, trampling, wildlife disturbance and wastewater discharge; carrying capacity and zoning limit cumulative effects.

Eutrophication sequence: nutrient enrichment → algal bloom → decomposition → oxygen depletion → hypoxia and dead zones.

Management follows adaptive cycles of monitoring, assessment, regulation and review; integrated coastal zone management coordinates competing uses across jurisdictions.

Validity: the investigation measures what it claims; controlled variables held constant, appropriate control group, and only the independent variable changed.

Reliability: consistency of repeated measurements; increased by replicates, standardised technique and calibration of instruments.

Accuracy: closeness to the true value; precision: closeness of repeated measurements to each other; random error affects precision, systematic error affects accuracy.

Uncertainty of repeated measurements is commonly reported as standard deviation; uncertainty of a single reading is typically half the smallest scale division.

Hypothesis must be testable and falsifiable; a prediction states the expected direction of change in the dependent variable.

Transect and quadrat sampling estimate abundance and distribution; random placement avoids bias, and percentage cover suits sessile organisms.

Mark-recapture abundance estimate: N = (M × C)/R, where M is marked, C is total in second sample and R is recaptures.

Correlation does not establish causation; confounding variables and sampling bias must be evaluated before inferring cause.

Evaluate evidence by checking sample size, replication, control of variables, statistical significance, and whether conclusions exceed the data.