Week 3 - Adaptations in sediment

Question 1

What types of environments do soft sediment habitats represent?

Answer 1

Sandy and muddy environments

They are the most widespread benthic ecosystem type in marine environments.

Question 2

What are the two types of sediments discussed in relation to life?

Answer 2

Cohesive and non-cohesive sediments

Question 3

What influences the organisms that inhabit soft sediment systems?

Answer 3

Composition and structure of the sediment

This includes physical, chemical, and biological conditions.

Question 4

What are key features of soft sediment systems?

Answer 4

• Three-dimensional structure
• Vertical gradients in sediment properties
• High species richness, abundance, and biomass

Question 5

Why do organisms in soft sediment systems need to adapt?

Answer 5

• Derive sufficient resources
• Reproduction
• Defend themselves and their resources
• Tolerate/respond to environmental changes

Question 6

What are the three categories of adaptations?

Answer 6

• Structural
• Behavioral
• Physiological

Question 7

What is ecological adaptation?

Answer 7

Phenotypic change occurring within an individual’s lifetime

Question 8

What is the difference between acclimatization and acclimation?

Answer 8

• Acclimatization: coordinated response to multiple environmental factors
• Acclimation: non-heritable, reversible adjustment to a single stressor

Question 9

What type of sediments do infaunal organisms prefer?

Answer 9

Cohesive sediments (mud)

Question 10

What are characteristics of cohesive sediments?

Answer 10

• Low energy
• Fine-grained
• Often with low oxygen levels
• Supports deposit feeders

Question 11

What adaptations do organisms in non-cohesive sediments exhibit?

Answer 11

• Rapid movement
• Suspension feeding

Question 12

What is the role of microphytobenthos in soft sediment ecosystems?

Answer 12

Stabilize sediments and contribute to primary production

Question 13

How do microphytobenthos migrate in cohesive sediments?

Answer 13

• Downward during high tide
• Return to surface during low tide

Question 14

What is the benefit of microphytobenthic migration?

Answer 14

• Protection from grazing
• Maximizes photosynthesis duration
• Supports high rates of carbon fixation

Question 15

True or False: Cohesive sediments are frequently flushed.

Answer 15

False

Question 16

Fill in the blank: Acclimatization is a response to _______ environmental factors.

Answer 16

multiple

Question 17

What type of organisms are microphytobenthos?

Answer 17

Unicellular eukaryotic algae, cyanobacteria, foraminifera, and flagellates

Question 18

What do many benthic species modify to track favourable conditions?

Answer 18

Behaviour

This includes minimizing predation risk and optimizing resource use.

Question 19

What is a key behavioral adaptation of the Plough Snail (Bullia spp.)?

Answer 19

Uses chemotaxis to locate carrion

The enlarged foot enables wave-assisted movement towards food.

Question 20

How does the Bivalve Clam (Donax variabilis) adapt to tidal movements?

Answer 20

Migrates with rising and falling tides

Morphological adaptations help control movement and stability.

Question 21

What is a behavioral adaptation of Mole Crabs (Emerita spp.)?

Answer 21

Rapid burrowing in unstable surf-zone sediments

Antennae adapted for filter feeding.

Question 22

What kind of behaviours do many benthic organisms exhibit?

Answer 22

Cyclic behaviours driven by environmental factors

Factors include tides, light cycles, and seasonal changes.

Question 23

What is the role of circadian rhythms in benthic species?

Answer 23

Regulate activity patterns, feeding behavior, and predator avoidance strategies

These rhythms are driven by internal biological clocks.

Question 24

What is the nocturnal circadian rhythm of Talitrus saltator?

Answer 24

Activity is restricted to darkness

Navigation is light-dependent, using silhouettes of sand dunes.

Question 25

What environmental factors influence the feeding behavior of Amphiura filiformis?

Answer 25

Tidal cycles and light cycles ## Footnote In strong tidal environments, activity follows tidal cycles.

Question 26

How do lunar cycles influence the reproductive behavior of Corophium volutator?

Answer 26

Exhibits circa-tidal swimming rhythms and seasonal changes ## Footnote Reproductive cycle shifts from semi-lunar in summer to lunar in winter.

Question 27

What do intertidal surveys in the Westerschelde estuary show about species responses?

Answer 27

Species-specific responses to tides and moon phases ## Footnote Different species peak at different tides.

Question 28

What are the primary drivers of biological rhythms in deep-sea organisms?

Answer 28

Food availability, temperature shifts, and geological events ## Footnote These organisms experience seasonal, inter-annual, and decadal changes.

Question 29

What are the spatial and temporal scales of environmental forcing factors?

Answer 29

Short-term, mid-term, and long-term ## Footnote Short-term: days to months; mid-term: years to decades; long-term: centuries to millennia.

Question 30

Fill in the blank: Many benthic organisms exhibit _______ behaviours driven by environmental factors.

Answer 30

cyclic ## Footnote These behaviours may be direct or indirectly influenced by internal biological clocks.

Question 31

True or False: Circadian rhythms are only influenced by external environmental cues.

Answer 31

False ## Footnote They are also driven by internal biological clocks.

Question 32

What are biogenic features constructed by benthic invertebrates?

Answer 32

Burrows, tubes, pits, and mounds ## Footnote These structures modify the environment and provide ecological benefits.

Question 33

What ecological benefits do biogenic features provide?

Answer 33

Enhancing oxygen exchange, stabilizing sediments, protecting against predation ## Footnote These benefits improve survival and resource access for organisms.

Question 34

What functions do biogenic features serve?

Answer 34

* Modify local hydrodynamic conditions * Provide shelter from predators and environmental stressors * Enhance nutrient cycling * Facilitate feeding strategies ## Footnote These functions are crucial in soft sediment environments.

Question 35

How do muddy sediments influence burrow morphology?

Answer 35

Fine-grained, forming elastic solid-like structures with limited permeability ## Footnote Oxygen and water exchange occurs mainly by diffusion.

Question 36

What is a common shape of burrows in muddy sediments?

Answer 36

U-shaped or multi-opening ## Footnote These shapes facilitate ventilation.

Question 37

What characterizes sandy sediments in terms of burrow construction?

Answer 37

Coarse-grained, porous, allowing water movement through interstitial spaces ## Footnote Oxygen can penetrate deeper, supporting I-shaped or J-shaped burrows.

Question 38

What are some strategies in burrow construction for infaunal organisms?

Answer 38

* Selecting specific sediments with optimal cohesion * Actively modifying burrows by adjusting diameter and depth ## Footnote These strategies ensure burrow integrity.

Question 39

What role do mucus secretions play in burrowing organisms?

Answer 39

* Strengthens burrow walls * Reduces sediment permeability * Helps in nutrient trapping * Provides defense against predators ## Footnote Mucus or organic linings enhance stability and food availability.

Question 40

How do burrows affect water flow in soft sediment ecosystems?

Answer 40

* Modify sediment permeability * Influence sediment transport * Facilitate waste removal ## Footnote These effects are crucial for oxygen and nutrient exchange.

Question 41

What adaptations do many species exhibit for feeding in relation to pits and mounds?

Answer 41

* Create pits to trap organic material * Generate water movement to concentrate food ## Footnote These adaptations enhance feeding efficiency.

Question 42

What is behavioral plasticity in benthic organisms?

Answer 42

Adjustment of behaviors based on environmental fluctuations ## Footnote This includes changes in burrowing depth, feeding habits, or activity patterns.

Question 43

How does gregarious behavior impact competition among species?

Answer 43

Some species cluster in colonies for protection while others compete for resources ## Footnote This behavior influences space and food availability.

Question 44

What is character displacement?

Answer 44

Evolution of distinct traits to reduce competition for resources ## Footnote This leads to morphological or behavioral divergence between populations.

Question 45

Provide an example of character displacement among mud snails.

Answer 45

Hydrobia ulvae becomes larger and Hydrobia ventrosa becomes smaller when coexisting ## Footnote This adaptation reduces competition by allowing exploitation of different food sources.

Question 46

True or False: Burrow stability is less important in sandy sediments than in muddy sediments.

Answer 46

False ## Footnote Burrow stability is crucial in both sediment types, though different strategies are employed.

Question 47

Fill in the blank: The interaction between biogenic structures and _______ plays a key role in soft sediment ecosystems.

Answer 47

water movement ## Footnote This interaction affects nutrient and oxygen exchange.