Marine Ecology and Ecosystem Dynamics: From Tides to Coral Reefs

What is the definition of ecology?

The scientific study of the processes influencing the distribution and abundance of organisms, their interactions, and the transformation and flow of energy and matter.

What are the limits to population growth?

Abiotic conditions, limiting resources, and interactions (inter- and intra-specific).

What is the difference between a condition and a resource in ecology?

Conditions are necessary for survival but not consumed (e.g., salinity), while resources are consumed until they become limiting.

What is neutralism in ecological interactions?

A rarely studied interaction where neither species benefits or is harmed.

What types of consumption interactions exist in ecology?

Predation, herbivory, grazing, browsing, and parasitism.

What are some limiting resources for competition among species?

Nutrients, food, light, space, and water.

What is amensalism?

An interaction where one species is harmed while the other is unaffected, such as biological disturbances.

Give an example of mutualism.

The relationship between clownfish and sea anemones, where both species provide benefits to each other.

What is commensalism?

An interaction where one species benefits while the other is neither helped nor harmed.

How can commensalism turn into parasitism?

If the density of the benefiting species becomes too high, it can harm the host species.

What are indirect interactions in ecology?

Interactions where one species affects another through a third species, often seen in complex communities.

What is competitive exclusion?

When one species outcompetes another, leading to the elimination of the less competitive species.

What are benthos in marine ecology?

Species that live on or buried in the bottom of the ocean, divided into mobile and sessile species.

What distinguishes pelagic species from benthic species?

Pelagic species live in the water column, while benthic species live on or in the ocean floor.

What is the significance of trophic structure in marine ecosystems?

It models the interactions and energy flow between different species, crucial for sustainable fishing practices.

What happens to energy and biomass at each trophic level?

On average, about 90% of energy and biomass is lost per trophic level.

How does the ocean contribute to carbon cycling?

The ocean absorbs CO2, which is taken up by primary producers and released back through respiration and decomposition.

What role do nitrogen-fixing bacteria play in the nitrogen cycle?

They convert inorganic nitrogen into organic material that can be incorporated into the food chain.

What is directional selection in evolution?

When conditions change and selection drives evolution towards a new optimum.

What is stabilizing selection?

A process where individuals that stray too far from the optimal balance are weeded out.

What is resource partitioning?

The sharing of a resource by specialization among competing species.

What are inducible defenses?

Defense mechanisms that are activated only in response to predators.

What is coevolution?

The process where predator and prey evolve in response to each other.

What is symbiosis?

A close association between two species, categorized by the benefits or harms to each.

What is the difference between facultative and obligate symbiosis?

Facultative symbiosis allows both organisms to survive independently, while obligate symbiosis means one or both depend on the other.

What causes tides?

The gravitational pull of the moon and the sun on Earth's water.

What is a spring tide?

A tide that occurs when the sun, moon, and Earth align, resulting in the highest high tides and lowest low tides.

What is a neap tide?

A tide that occurs when the sun and moon are at right angles to each other, resulting in moderate tides.

What are some stressors for marine organisms at low tide?

Desiccation, temperature fluctuations, strong light, altered predation, and oxygen availability.

What adaptations do marine organisms have to survive low tide?

Morphological, behavioral, and physiological adaptations, such as moving to crevices or developing heat-stress proteins.

Why is it beneficial for sessile organisms to cluster together?

To lower the temperature of the area at low tide, similar to a forest's cooling effect.

What is a positive feedback loop in seaweed growth?

A young seaweed expands its damp area, allowing more young seaweed to grow.

How much denser is water compared to air?

Water is 830 times denser than air.

What happens to a wave as it approaches the shore?

The wave becomes steeper and faster due to friction with the bottom.

What is wave refraction?

When a wave approaches the coast at an angle but hits the bottom directly parallel.

Why do organisms on headlands need adaptations for high wave energy?

Because wave energy concentrates on headlands, requiring organisms to withstand stronger forces.

What are two adaptations of organisms to deal with wave stress?

Small size and flexibility.

What is Ubreak in relation to kelp?

It measures resilience to wave mortality; lower values indicate higher likelihood of breaking.

What is the significance of bull kelp in terms of strength?

Bull kelp is the strongest seaweed, requiring tractors to remove it from reefs.

What is zonation in marine ecosystems?

The appearance of clear bands of different types of organisms across spatial gradients.

What are the four spatial gradients that affect marine zonation?

Latitude, elevation (up/down), and coastline (horizontal).

What organisms are typically found in the upper intertidal zone?

Periwinkles, limpets, lichens, and encrusting algae.

What organisms dominate the middle intertidal zone?

Barnacles and mussels.

What is the primary difference between rocky shores and intertidal soft-bottom habitats?

Rocky shores have larger sediments, while soft-bottom habitats have smaller sediments like clay and silt.

How does sediment size affect water drainage?

Larger particles drain quickly due to larger pores, while fine sediments drain slowly due to compactness.

What is the primary food source for intertidal soft-bottom communities?

Detritus extracted from sediments.

What adaptations do infauna have to survive in soft-bottom habitats?

They can pump oxygen-rich water from the surface through their burrows.

What is meiofauna?

Small soft-bottom animals that live in the spaces between sediment grains.

Why are deposit feeders more common on mud bottoms than sand?

Mud contains more organic matter, while sand is abrasive and hard on the digestive system.

What is the role of bioturbators in sediment habitats?

They help oxygenate the sediment by disturbing it.

How do clams and cockles move through sediment?

They change the shape of their muscular foot to anchor and pull their body along.

What is the main challenge for suspension feeders in muddy bottoms?

Their filtering mechanisms tend to get clogged by high sediment amounts.

What is the difference between infauna and epifauna?

Infauna live within the sediment, while epifauna live on top of it.

What adaptations do sea cucumbers have to avoid predation?

They have a bad taste and physical defenses like sticky filaments.

What is the impact of wave action on sediment composition?

Wave-exposed coasts typically have larger sediment particles than tide-dominated estuaries.

What is the significance of seagrasses in soft-bottom habitats?

Seagrasses are the most common large primary producers, unlike seaweeds.

What do deposit feeders do to suspension feeders in estuaries?

Deposit feeders disturb sediments, clogging suspension feeders' feeding structures and burying their larvae.

Where do suspension feeders dominate in estuaries?

Suspension feeders dominate in sandy sediments with wider interstitial spaces.

What organisms inhabit the upper beach of intertidal soft bottoms?

Amphipods such as beach hoppers and sand fleas, and isopods.

What types of animals are found lower on the beach?

Polychaetes, clams, and other animals.

Define an estuary.

A semi-enclosed coastal area where freshwater from rivers meets the sea.

What is the salinity of freshwater and marine water?

Freshwater = 0 ppt of salt; Marine = 35 ppt of salt.

Why are estuaries important for civilization?

They provide fresh drinking water and seafood, and the surrounding land is fertile for agriculture.

What type of substrate is common in most estuaries?

Sand or soft mud.

What are drowned river valleys?

Estuaries formed by sea level rise, where seawater penetrates into river valleys.

What are the four geomorphological classifications of estuaries?

Tectonic, Fjord, Drowned river valleys, Lagoon-type/bar-built.

What characterizes a salt-wedge estuary?

River flow is stronger than marine tidal mixing, leading to a salinity gradient.

What is an isohaline?

An area within an estuary that has a specific salinity level.

What is a vertically well-mixed estuary?

An estuary with a uniform salinity profile due to turbulent mixing.

What is a partially mixed estuary?

An estuary with a moderately stratified condition due to tidal forces and river flow.

What happens in an inverse/reversed estuary?

Evaporation exceeds freshwater inflow, creating a hypersaline zone.

How does the Coriolis effect influence estuarine circulation?

In the southern hemisphere, freshwater is deflected to the left; the reverse occurs in the northern hemisphere.

What environmental gradients are important in estuaries?

Salinity, sedimentation, nutrients, light, topography, temperature, and hydrodynamics.

What is the primary challenge marine fish face in estuaries?

Maintaining homeostasis in varying salinity conditions.

What are stenohaline organisms?

Organisms that can only survive within a narrow salinity range.

What are euryhaline organisms?

Organisms that can tolerate a wide range of salinities.

How do osmoconformers maintain osmotic balance?

They allow their body fluids to change with the surrounding water salinity.

What is the role of osmoregulators in estuarine environments?

They maintain a constant internal salt concentration regardless of external salinity.

What adaptations do plants in estuaries have to cope with salinity?

They actively absorb salts and concentrate harmless solutes to match outside concentrations.

What are mudflats in estuaries?

Habitats that support infauna and are productive due to organic material from river input.

What is the significance of salt marshes in estuaries?

They are intertidal areas with extensive grassy areas and a strong zonation pattern.

How do estuarine species cope with salinity fluctuations?

Many have behavioral adaptations, while others maintain osmotic balance through physiological means.

What are salt marshes known for?

They are the only marine systems with insects and deposit a lot of detritus.

How does the Coriolis effect influence salt marshes in the northern hemisphere?

Salt marshes tend to be more extensive on the left side of estuaries than on the right side.

What misconception about snails in Virginia salt marshes has been corrected?

Snails were thought to be detritivores but are actually grazers that feed on grasses.

What impact has the decline of predators like crabs and alligators had on snail populations?

The snail population has exploded due to the decline of their predators.

How can mudflats be converted to increase biodiversity?

By placing seaweeds on mudflats or converting them to oyster reefs.

What role do marsh plant roots play in salt marshes?

They stabilize the muddy bottom of salt marshes.

What is the subtidal zone?

The area extending from the low tide level on the shore to the shelf break.

How does the width of the continental shelf differ between passive and active margins?

The continental shelf is much wider on passive margins than on active margins.

What are the physical characteristics of the continental shelf?

Depth, area, environmental gradients, waves, and light.

Why is light an important characteristic of the continental shelf?

It affects primary production and the visibility of organisms.

What happens to light as depth increases in the ocean?

There is an exponential decrease in light penetration.

What is the compensation depth in marine environments?

The depth at which production equals respiration, typically around 1% sunlight absorption.

What is the photic zone?

The area above the compensation depth where light is sufficient for photosynthesis.

What is a Secchi disk used for?

To measure water clarity and determine the depth at which light penetration decreases.

What sampling methods are used in the subtidal zone?

Bottom trawl, heavy scraper, diving, remote sensing, and Van Veen grab.

What is shifting baseline syndrome?

The phenomenon where current natural states are compared only to recent times, obscuring true changes.

What is meroplankton?

Larvae released by organisms that drift in the water column before settling down.

How do feeding methods vary in the sub-tidal zone?

They are dominated by filter feeding and deposit feeding, depending on sediment size and turbulence.