Week 21

Question 1

How are marine and estuarine ecosystems organised?

Answer 1

Physical, chemical and biotic factors interact to structure communities.

Question 2

How do habitat templets work?

Answer 2

Communities and species within them can be defined by simple axes so long as they are pertinent to the organisms in question.

Distance / Productivity / Substrate characteristics

Question 3

Disturbance affects parameters (my removing or opening space) indirectly, how?

Answer 3

Any relatively discrete event that removes organisms and opens up space/resources that can be used by others​:

• Predictable: eg tide, waves, seasons​
• Unpredictable: eg boat passage, storms, asteroids​

Question 4

Explain space and time in terms of disturbance?

Answer 4

μm; ms-s; eg chemical reactions, bacterial driven processes​

0.1 – 1m; mins – days; eg bioturbation, feeding pits, diatom mat formation​

100 – 10000m; mo – years; eg hurricane events, iceburg scour​

> 10000m; years – decades; eg volcanic activity, anoxic events, global warming, recolonisation of megafauna​

Question 5

How does disturbance occur by ecosystem engineers?

Answer 5

Individual to population scale – additive effect​

• complete reworking of surface sediment​
• impact upon meiofaunal community​

Question 6

Example of disturbance by ecosystem engineers?

Answer 6

Crabs and flamingos acting as ecosystem engineers by resurfacing the land, which feeds back positively to them allowing their sustained positivity.​

Therefore biology may have more impact than a tide in terms of disturbance.

Question 7

What is the intermediate disturbance hypothesis (IDH) commonly occurring in sea grass or coral reefs?

Answer 7

If disturbance occurs too frequently then few organisms can persist​

If conditions are stable, then specialist organisms dominate through competition​

Thus, species richness is highest at intermediate disturbance frequencies​

Question 8

Currents and Gyres in terms of ecosystem diversity in marine and estuarine ecosystems?

Answer 8

Circulating water masses that restrict particular connectivity at certain areas eg Antarctic circumpolar current​

Important over evolutionary timescales where organisms have tapped into the more efficient transport if they utilise the currents to maintain their life cycle over certain areas eg salmon, tuna, turtles, etc.

Question 9

How can wave energy cause disturbance?

Answer 9

Surface gravity waves caused by friction of wind passing over water.

Wave height ~ length/20

When waves touch the bed, ellipses become compressed into horizontal motion and wave breaks when depth = 4/3 wave height.

Question 10

What may affect water movement, therefore marine and estuarine ecosystems?

Answer 10

gravitational pull of the moon and the sun and the earth rotating produce tides.

Tidal amplitude affected by coastline configuration

Question 11

Movement of water down to tides is responsible for…

Answer 11

A lot of the zonation we see on shore lines.

And this related to the structure and function noticeable in ecosystems (and species that can survive) within the specific zones:
- Littoral
- Infralittoral
- Sublittoral
- Circalittoral
- Offshore circalittoral

Question 12

Mean velocity of water depends upon?

Answer 12

Gravity
Slope
Mean flow depth
Resistance

Typically the faster velocities are near the surface, and due to friction water closer to the bed is slower. Therefore surface velocity isn’t necessarily what organisms on the bed experience making it more habitable.

Question 13

How may shear stress cause disturbance?

Answer 13

Shearing force of water on the bed is dependent upon​: density of water, gravity, hydraulic radius, energy slope.

Proportion of fine particulate matter in the sediment increases downstream because slope and shear stress decrease

Question 14

How does turbidity occur due to water movement.

Answer 14

Turbulence can be made when freshwater meets salt water (eg at an estuary), which will impact the life there both directly and indirectly

Question 15

How does flow of water impact plants/marine life?

Answer 15

Effects of flow on macrophytes / macroalgae

It is evident that environmental pressures placed on an organism can be noticed by its structure eg in sea grass experiencing hydraulic flow.

Eg some organisms experience Hydrodynamics and will adapt their body type/features to align to the flow: rheotaxis
Also evident in many fish kind, and all marine/estuarine organisms (form = function)

Question 16

Density of medium (water) affecting ecosystems?

Answer 16

Water is 800-1000x more dense than air ​and at 20oC - it has 50x more viscosity ​

Water density and viscosity varying according to temperature and ionic conc.​

Support for larger organisms​

For a fluid of given dynamic viscosity, motion controlled by velocity and size and quantified by Re: the Reynolds number​

(velocity x size)/dynamic viscosity​

Re < 1000 then seawater is ‘sticky’​

​Interstitial water​

Question 17

How much more dense is water than air, what about visosity? What does this mean for organisms living within it?

Answer 17

Water is 800-1000x more dense than air ​and at 20oC - it has 50x more viscosity ​

Therefore sea water is the best medium for life, despite it being sticky (for cilliates) and so hosts the largest organisms on earth eg The Whale.

Question 17

What is salinity in terms of sea water?

Answer 17

Dissolved ions expressed as:​ mass (mgL-1), ppm or chemical equivalents (meqL-1)​
Total amount of dissolved material in a water sample is the salinity​

​Constancy of seawater allows for determination by measuring a single constituent​
- chlorinity: [Cl-], where salinity = 1.80655 [Cl-] ​
- expressed as ppt or ‰, or now Practical Salinity Units (PSU)​

Salinity in freshwaters highly variable​
- sodium chloride​
- carbonates and hydrocarbonates​

Hypersaline conditions in bays, reef lagoons

Question 18

What are the costs of salinity?

Answer 18

Organisms either maintain body fluids in equilibrium with surrounding medium (osmoconformers) or they osmoregulate

Physiological stress (cost) associated with maintaining fluid balance overcoming osmotic potential (dilute to concentrate)

Question 19

How does salinity change?

Answer 19

From the river mouth to the ocean salinity increases and this level can also change due to:
Seasons, wind, expose of mouth of river, tides.

All of which will affect how freshwater and salt water will mix (causing turbidity) of flow and therefore impacting organisms that live in that area.

Question 20

Who studied Stenohaline vs euryhaline Gammarus spp and impacts of the mixing estuarine zone and the sea with increasing salinity gradients occurrance?

Answer 20

Spooner 1974

Question 21

Solar radiation is important to aquatic systems for two reasons. What are these?

Answer 21

Energy source controlling metabolism through the conversion of solar energy to chemical energy via photosynthesis​

Some radiation is absorbed or dissipated as heat affecting thermal structure and stratification, and circulation patterns​

Question 22

What is the electromagnetic spectrum?

(Don’t need to know everything exact, just a summary will do!)

Answer 22

Light is received as quanta or photons which have wavelength (λ) and amplitude (A)​

Short wavelength, high energy gamma rays (about 100 nm or 1000 Å) ​

Long wavelength, low energy radio and power transmission waves (> 3000 nm or 30,000 Å)​

Visible spectrum is 400 (violet) to 750 nm (red)​

Infrared > 750 nm​

UV < 400 nm (UV-A 315-400 nm, UV-B 280-315 nm) ​

Photosynthetically active radiation (PAR) ie radiant energy 400-700 nm wavelengths ​

Chlorophyll a has absorption peaks at 445 and 660 nm​

Bacteria…​

PAR accounts for about 46-48% of the total energy hitting earth’s surface

Question 23

Formation processes of aquatic systems?

Answer 23

Results from a number of different natural and artificial processes

Causes which bring an ocean basin, lake or river/estuary into being are often interlinked.

Thus waterbodies with similar origins have similar physical characteristics despite being separated by or within continents​

Cascade to biotic similarities; hence often helpful to classify according to causation​

Question 24

Global marine/estuary diversity can be measured using what curve. What is this?

Answer 24

Hypsographic curve​ Cumulative percentage of the Earth below a given elevation​ ~71% is below sea level ~45% abyssal; ~25% slope​ Rise in sea level of 100m would reduce land area by ~5%​

Question 25

What is the approximate volume as a percentage in each of the defined aquatic systems?

Answer 25

Oceans = 96.5%* Glacial ice = 1.8% Groundwater = 1.7% Freshwater lakes = 0.008% Saline lakes = 0.006% Atmosphere = 0.001% Rivers = 0.0001%*

Question 26

What is 'dynamic' water?

Answer 26

Does not consider water movement on a global scale​ ​All connected via an active hydrological cycle​ Movement represented generally anticlockwise​ Some mechanisms act in a reverse direction; most important as dashed lines​ Precipitation on ocean surface negligible in terms of biology​

Question 27

The majority of ocean habitat is what?

Answer 27

'open' ocean eg water column or pelagic habitat. Different mechanisms operating at different depths result in relatively discrete environments separated by depth​ eg temperature, light, oxygen etc​ Despite being ‘connected’, barren-ness of pelagic zone hinders or prevents movement of most organisms as it creates a behaviour barrier – space effect​

Question 28

What is Pelagic habitat structure?

Answer 28

physical & chemical structure ‘typically’ homogenous in horizontal dimension​: ​- vertical heterogeneity associated with chemical and thermal stratification​ ​- energy flow largely through phytoplankton & bacterial pathways

Question 29

What is benthic habitat structure?

Answer 29

substantial heterogeneity in horizontal & vertical dimensions:​ - physical – substrate, debris, macrophytes​ - chemical – steep gradients associated with O2​ ​- energy flow arguably more complex:​ = Primary Production from microphytobenthos, macrophytes, periphyton, chemosynthesis​ = allochthonous inputs from estuaries​ and out into the sea = sedimentation of pelagic Primary Production​

Question 30

Benthic versus pelagic

Answer 30

More complex habitat ie a coral reef compared to an empty fish bowl!

Question 31

What is the depth zonation of the pelagic?

Answer 31

Simplistic​ Photic zone in open waters much greater than nearshore (neritic)​ Epipelagic, Mesopelagic, Bathypelagic, Abyssalpelagic, Hadalpelagic

Question 32

Depth zonation: Vertical distributions of limiting parameters (eg Oxygen minimum zones, temperature, , etc) can result in what?

Answer 32

Habitat squeeze with consequences for fauna Therefore habitat is restricted. May be permanent or seasonal in terms of space and time

Question 33

How is pelagic all connected at surface ocean circulation?

Answer 33

Currents are generated by wind friction​ Thus global pattern of currents reflects that of atmospheric movement​ ‘Piling’ of water on the down current side​ ​Counter currents​ Land masses interfere​

Question 34

How is pelagic all connected at deep ocean circulation?

Answer 34

Deep currents are independent of the surface​ Initiated by surface waters cooling at high latitudes downwelling​ In most of the oceans, the water in contact with the abyssal plain is Antarctic Bottom Water downwelling from Ross & Weddell Seas​

Question 35

Why may deep ocean currents be failing?

Answer 35

Antarctic Circumpolar Current (ACC), 5x stronger than the Gulf Stream, 100x stronger than the Amazon​ Driven by Freshwater from melting Antarctic ice​ diluting saltwater​ and cool water moving away from the continent ​ACC 20% slower by 2050​ Negative feedback​ = acting as a buffer zone to the Antarctic to keep warmer water at bay and so effects of climate change. But if this is breaking down, it will increase the effects of the 'buffer zone'. ​(Sohail et al, 2025​)

Question 36

How is pelagic all connected at localised connectivity at 'edges'?

Answer 36

Upwelling & downwelling against the land connect water masses and habitats ​

Question 37

What are fronts in terms of marine and estuarine biology? What can these fronts be mapped to show?

Answer 37

Where two different water messes meet (may also be classified as an 'edge') - Can be mapped to show differentiation in temperature, plant primary production, etc.

Question 38

What water process is important for marine predator feeding?

Answer 38

Mass water movements (disturbance), for example more copepods/algae/plankton will more likely be found where the water currents/circulations mix (and where freshwater may meet sea water).

Question 39

What water process is important for migrating animals?

Answer 39

Mass water movements for these animals to complete their life-cycle. Eg Fish that reside in estuaries, move to a current to aid travel to a warmer place to hatch, before moving through another circulation current to another continent, or migrate back to the estuary. Efficient to aid weaker swimming states (eg larvae) and allows less food consumption. If these streams collapse it will affect other marine organisms that utilise these currents to migrate and complete life cycles.

Question 40

Pelagic habitat summary?

Answer 40

Relatively simple structured mostly by physicochemical qualities, hence ‘barren’ – little life​ Where that life is found tends to be at a disturbance or edge

Question 41

What is the difference between arctic and antarctic ice habitats?

Answer 41

Arctic = Forms on the edge of many continents. Lots of freshwater run off from the land masses in the arctic so its more fresh, 'old' and cold in its formation Antarctic = Forms on the edge of the Antarctic ocean. Formed on a seasonal basis where the salt sea water will freeze, 'new' and relatively warm formation.

Question 42

What % of benthos oceanic habitat is deep sea floor / abyssal plain?

Answer 42

~45% and is relatively poorly connected and relatively few organisms persist there.

Question 43

What % of benthos oceanic habitat is ocean ridges?

Answer 43

~33% and can be considered as 'new' sea floor with clear lines of volcanic activity Study: 40day scientific cruise recorded 160 newly recorded species and potentially 50 new to science. - This may be driven by primary production where zonation is evident to provide nutrients, etc (due to methane seep, hydrothermal vents) for species.

Question 44

Oceanic benthos habitats: the continental shelf and slope?

Answer 44

Continental shelf and slope can be extremely dynamic​ ~20% of bed surface​ ‘Width’ determined by plate characteristics​ ​ Upper continental shelf comprises accumulated material from ‘land’ ​ relatively unstable and thus likely to move downslope​ generate turbidity currents

Question 45

The coastal zone makes up what % of oceanic benthos?

Answer 45

~3%​ Most diverse in terms of habitats… in the smallest area​ ​- Inter-tidal zone​ - Coral reefs​ - Estuaries​ - Coastal wetlands​ Considered to be ‘Well connected’​ habitats (access light, nutrients, energy, etc)

Question 46

What processes affect water distribution and light penetration, and how is irradiance at different depths calculated?

Answer 46

Reflection / Scattering / Absorption​ Irradiance – # of photons passing a unit area (mE s-1m-2) ​ Light Attenuation ​ Iz = Io e-kz​ Where: ​ - Io is irradiance at surface ​ - Iz is the irradiance at depth z​ - k is the extinction coefficient​ Measure k directly using a photometer or estimate from Secchi depth where k = 1.7zs​ ~53% of total light energy transformed to heat within top meter

Question 47

How is light penetration different in the open ocean versus in coastal waters?

Answer 47

Light penetration different in open vs coastal ocean waters because turbidity drives molecules from the land to water, causing a decrease in light penetration in coastal areas compared to open ocean.

Question 48

Colour and transparency is described by what?

Answer 48

Dissolved molecules/particles (eg carbon) in the ocean at the time. So we describe turbidity not colour. True colour is mostly impacted by DOC (dissolved carbon molecules)

Question 49

Different names for zonation of light penetration?

Answer 49

Sunlight zone = Euphotic zone Twilight zone = Dysphotic zone Midnight zone = Aphotic zone (Biodiverse and bio phosphorescence examples of life here and show strange evolutionary behaviour to increase survival/reproductive success.)

Question 50

What is Boyle's law? What does it explain?

Answer 50

The volume of a given quantity of gas at constant temperature varies inversely with pressure. This law is an explanation for challenges of aphotic zone in ocean = organisms do not suffer decompression gasses.

Question 51

How does the ionic character of water influence its density in relation to temperature, and at what temperature is water densest?

Answer 51

​Ionic character of water affects how its density reacts to temperature​ Water densest at 4oC; changes in density per degree are slight around this point​ At higher temperatures, changes in density per degree become increasingly large

Question 52

What are the characteristics of the layers in a stratified water column where wind and wave stress are minimal?

Answer 52

- Where or when wind / wave stress is minimal​ - Upper part – well mixed – epilimnion​ - This floats on colder, denser hypolimnion​ (aka thermocline) - Between the two is a stratum of thermal discontinuity – the metalimnion​ - Typically >1oC m-1

Question 53

What are the structural and global significance of sea ice, and how does it form?

Answer 53

Sea ice / pack ice has structural properties for the local habitat​ also important in driving global ocean thermohaline circulation patterns via deep water masses​ Seawater freezes at -1.8oC (Eicken 2003)​ Crystals rise and aggregate into slicks of grease ice​ period of inoculation​ Forming Pancake ice or Congelation ice ​

Question 54

What are the characteristics and changes in brine channels in sea ice, and how do they affect salinity?

Answer 54

Semi-solid matrix permeated by pores or brine channels​ Hypersaline conditions as salts expelled (Krembs et al 2000)​ ‘Cold’ ice – less volume in channels; salinity higher​ ‘Old’ ice – loss of brine due to expulsion and gravity

Question 55

What occurs when melting of sea ice happens?

Answer 55

​Upon ice break or melt​ Freshwater lens can stabilise water column – effective frontal system algal blooms from ice matrix inoculum​ Aggregation into marine snow​ Crustacean grazing – repackaging as faecal pellets flux of 660 mgCm-2d-1 (Cadee 1992) Possible impact of 'pulse' on the benthos

Question 56

What factors contribute to oxygen availability in aquatic environments, and how do organisms adapt?

Answer 56

Uneven distributions of O2 in aquatic environments (seawater 20% less)​ ​Many morphological, biochemical and behavioural adaptations ​ ​1% oxygen by volume compared to ~21% in air​ 100m increase in altitude reduces solubility by about 1.4%

Question 57

Example where O2 intake adaptations has occurred in marine organisms: sea worms

Answer 57

Cellular exchange of O2 and CO2 require gaseous diffusion across a boundary, thus protists and small metazoans use their entire SA

Question 58

Example where O2 intake adaptations has occurred in marine organisms: whales

Answer 58

These organisms may face decompression gases compared to fish and worms as they have complex breathing systems (eg lungs)

Question 59

How does the temperature range and stability in aquatic environments affect aquatic life?

Answer 59

Aquatic life typically experiences a narrower range of temperatures and more stable thermal regimes compared to terrestrial systems. This temperature stability impacts key biological processes such as metabolic rate, growth, development and final body size. They adapt their features for the purpose of function.

Question 60

Explain the ratio of salinity : temperature : oxygen impacting marine organisms

Answer 60

All of these impact life in marine ecosystems contributing to life forms able to survive there.

Question 61

How does water's tendency to form hydrogen bonds at the water-air boundary relate to surface tension and the communities associated with it?

Answer 61

Water's tendency to form hydrogen bonds with itself creates a high surface tension at the water-air boundary. This physical property supports entire communities, collectively known as the neuston, which inhabit this boundary layer: - Epineuston live on or above the water surface. - Hyponeuston reside just below the surface

Question 62

How does the water-sediment boundary contribute to benthic habitats and biological diversity?

Answer 62

The water-sediment boundary exhibits differing properties, creating opportunities for significant biological contributions This boundary supports the benthos, organisms that inhabit the sediment, by providing complex and varied habitats that accommodate diverse life forms.

Question 63

What on saltmarshes and intertidal flats is impeded by flat topography?

Answer 63

Inputs of water exceed evaporation and outflow is impeded by flat topographu

Question 64

Benefits of flat topography on mutflats?

Answer 64

Waders: - Feeding - Resting - Nesting Therefore, many Migratory birds can stop-over at these areas. Allowing for mass movements with a safe place to rest on the way

Question 65

Seagrass meadows as an edge habitat for organisms?

Answer 65

Relatively few species of flowering plants, Extensive meadows on shallow sheltered coasts Highly productive 30% more biomass than adjacent sand habitats 20% of worlds largest fisheries Important for nurseries (first life stages of invertebrate and fish eg eggs - larvae stages)

Question 66

Mangrove distribution around the world?

Answer 66

40% in Asia Mainly located in the tropics.

Question 67

Describe Mangrove ecology (prop roots and canopy)?

Answer 67

Prop roots substrate for epiphytes, biofilm matrices and grazing grounds for inverts. Root refugia zone Canopy of Rhizophora ideal nesting habitat for terrestrial birds

Question 68

How do mangroves act as ecosystem engineers?

Answer 68

As more sediment moves into the intertidal mudflat, mangroves can settle as sediment trapping and stabilisation has occurred. Once mangrove established, organisms can use as habitat and further trapping can occur, aiding organisms closer to land via "protection"

Question 69

How can mangroves impact fish lifestyle?

Answer 69

Many organisms use in early stages of life before migrating to the 'open waters' of a coral reef. Reefs near a mangrove have better functioning ecosystems +diversity than reefs and mangroves that are alone.

Question 70

What is the taxonomic Latitudinal gradient like in coral reefs?

Answer 70

Strong and functional diversity of fish, peaking in the tropics

Question 71

In coral reefs what leads to high fish endemism?

Answer 71

Diversity of habitats and therefore niches

Question 72

What are the fish assemblages on coral reefs?

Answer 72

Strong biotic interactions are characteristic of coral reef systems​ Very productive habitats Environmentally ‘stable’ conditions Diverse and speciose assemblages characterised by trophic specialists​

Question 73

What is the link between reefs and beaches?

Answer 73

Some fishes are ecosystem engineers producing and moving sand and gravel​ They therefore can control resource availability by modifying, maintaining & creating habitat​ ​Parrotfishes are greatly responsible for this

Question 74

Explain coral reef biotic feedback in a coral-dominant reef versus a coral-depauperate reef?

Answer 74

Coral-dominant reef: - Fish (increased growth) eat microalgae (herbivory) - Fish also help corals (nurtients increase growth), corals also prevent algal colonisation Coral-depauperate reef: - Fish increase nutrients growth, therefore eat microalgae, but microalgae is high. - Therefore while fish aid coral growth, algae reduce recruitment, growth and survivor ship of corals.

Question 75

True or false: Edges are important for breeding grounds?

Answer 75

True! For seabirds, turtles, etc. These marine feeding birds also allow connectivity via cross ecosystem boundary subsidies. The guano the birds leave transfer nutrients

Question 76

Explain Pelagic - benthic connectivity?

Answer 76

Assuming most life is in the upper zones of waters, their feaces, migration and death will move down the water colunm. However, large marine animals such as whales, bring faeces, urea, etc back up to the surface after a dive. And re-secrete these, starting the cycle again

Question 77

How are the zones in the ocean connected by gravity?

Answer 77

Fuelled from above: pelagic-benthic coupling​ Ultimate manna from heaven….. whale-fall… and to lesser extent, tree-fall​ Point source of nutrients​

Question 78

Most marine organisms are stenohaline, what is this?

Answer 78

tolerant of only small changes externally or salt.

Question 79

What is an euryhaline organism?

Answer 79

Organisms that can osmoregulate over wide range of environmental salinities. Be that for all or part of a life-cycle.

Question 80

How do Snook fish deal with salt?

Answer 80

Spawn in coastal marine, Larvae and juveniles develop in brackish water Adults may overwinter in freshwater

Question 81

How do salmon deal with salt?

Answer 81

Adults Spawn and die within 2 weeks in freshwater. Eggs hatch alevin, grow into fry and then parr. Their next stage is smolt and they group together and head out to sea. Adults stay in the sea for 1-8 years, before heading back to freshwater to spawn.

Question 82

Mangroves are facultative halophytes, what is this?

Answer 82

Saltwater is not a physical requirement for growth. Most can grow well in freshwater, but many communities are not usually found in strict freshwater environments. Found where salinity ranges from 0-90%

Question 83

Morphological and physiological adaptations of Mangal species for internal ionic regulation?

Answer 83

​1. Salt excluding species - do not take salt water internally. - Separate freshwater at root surface by creating non-metabolic ultra-filtration system. - Transpiration at leaf surface creates negative hydrostatic pressure in xylem and 'reverse osmosis' occurs at root surface. 2. Salt excreting species - excrete salt through glands on leaf surfaces. - Temp sensitive enzymatic process involves active transport

Question 84

How does Enteromorpha regulate salt?

Answer 84

Enteromorpha from estuaries possesses thinner & ‘stretchier’ cell walls than fully marine species, allowing for changes in tissue water content via cell volume​ more readily as the water around them changes

Question 85

How do fish Osmoregulate?

Answer 85

To counter water loss in marine water, teleost fish drink water, absorb at gut and excrete sodium and chloride ions at gills, other divalent ions at gut and kidney. Salt balance: - Gut lumen and urinary bladder important - Retention of CO2 and subsequent hydration for anion exchange mechanism - Helps absorbing water - Hormonal control

Question 86

Examples of fish that avoid osmoconformers?

Answer 86

Hagfish and lampreys

Question 87

How do sharks osmoregulate?

Answer 87

Waste products must be removed from body as breakdown of proteins results in ammonia formation. Ammonia and ammonium can be removed by gills; urea lost at gills or in urine. But, waste can also be retained to help with osmoconformation via ion-regulation

Question 88

Are fish really cold-blooded?

Answer 88

Most fishes are at ambient temperature​ Thermal stability of water confuses issue of poikilothermy….​ ​Better to refer to source of heat ie ectotherm in case of most fishes​ - some fishes can be classified as endotherms​ - metabolic trade-offs​

Question 89

Give an example of fish that utilise endothermy to maintain temperature?

Answer 89

Endothermic fish conserve heat generated by swimming muscles. EG: Bluefin tuna, Maintain muscle temperatures of 28-33 degrees. Especially in large pelagic predators, development of thermogenic cells stimulated by CNS, routing of heat from swim muscles to CNS. This is known as regional endothermy. For example: Marlins use this method of heat.

Question 90

How do fish deal with fluctuating temperatures?

Answer 90

Diel or seasonal changes are counted by cellular or sub-cellular mechanisms: - 'Switching' on and off genes responsible for protein manufacture.` - Increasing enzyme production to aid catalysis at low temperatures - Production of iso-enzymes - Using unsat/sat fatty acids in membranes - Reallocation of red and white muscle

Question 91

Marine Mammals need to maintain internal temperature, how?

Answer 91

- Countercurrent system - Peripheral vasoconstriction - Insulation

Question 92

What are morphological and physiological adaptations of mangrove for extracting oxygen from sediments and water around them?

Answer 92

- O2 conc normally sufficient where plants a present - Anaerobic conditions are common in mangrove/wetland sediments - Lenticles and spongy tissue in roots/modified branches facilitates gaseous exchange - Spongy pneumatophores extend up to 20cm above the sediment - Prop roots possess many lenticles which allow O2 diffusion with passage underground roots via aerechyma - Peg roots and pneumatophores may be present when found in O2 deprived sediments

Question 93

Aquatic breathing in fish versus breathing in humans (%)?

Answer 93

Evolved effective systems for extracting oxygen from water, - Some extract 80% O2 - Humans manage 25% O2 taken into lungs

Question 94

1. Gills and counter-currents are an adaptation for aquatic organisms (Fish) to breathe. What is this? 2. How do they ventilate?

Answer 94

1. Blood flow opposite to that of water flow ensures a constant diffusion gradient across entire lamellar surface​ 2. Majority of fish 'pump' ventilate using buccal and opercular cavities.

Question 95

How do continuous swimming fish ventilate compared to benthic fish?

Answer 95

Continuous swimming fish 'Ram' ventilate Benthic fish utilise spiracles (like insects)

Question 96

Why do larger fish suffer more during periods of low oxygen?

Answer 96

Gill surface area. More active fish that predate on other fish have larger gill area whereas benthic, inactive fish have smaller gill area.

Question 97

How does gas exchange occur at tissues and gills?

Answer 97

Uptake of CO2 enhanced by enzyme – carbonic anhydrase in the RBCs​ ​ Converts CO2 to H2CO3 which dissociates to form HCO3- and H+​ ​ Increase in H+ cause pH to drop​ ​ Bohr effect​ ​ ​ Bicarbonate diffuses out of RBCs permitting further uptake of CO2​ ​ Chloride shift balances loss of negative charges​

Question 98

How is gas transported in marine organisms (fish)?

Answer 98

Some in the plasma via haemoglobin Binding at respiratory surface and release at site of need: influenced by pH At tissues = production of carbonic acid lowers pH At gills = Decrease in carbonic acid via CO2, release, thus pH rises.

Question 99

What is the fish efficient circulatory system?

Answer 99

- Single atrium - Single ventricle

Question 100

What are other mechanisms of gas exchange in marine organisms that don't use gills?

Answer 100

Cutaneous gas exchange eg Anguilidae ~30% via skin

Question 101

Some fish can alter how they breathe. Facultative versus obligate?

Answer 101

Facultative - supplementing gill respiration when required​ ​Obligate - will drown if no access to water surface!​ ​Typically tropical freshwater or estuarine; >40 genera​

Question 102

Describe the mammal dive physiology?

Answer 102

Mammal diving reflex - triggered by temperature at the face: - Bradycardia – heart rate slows​ - Vasoconstriction – capillary volume reduced​ - Blood shift – plasma and cell water diffuse into chest cavity​ to (prevent organ crushing)

Question 103

How can buoyancy regulation be energetically costly for pelagic fishes?

Answer 103

Teleosts reduce the cost via the swim bladder: the positive buoyancy provided by air counters the negative buoyancy of the tissues, enabling neutral buoyancy… remain suspended in the water​ Regulation of the swim bladder volume is necessary upon depth change to avoid negative buoyancy ie sinking!​

Question 104

Where is the swim/gas bladder on fish?

Answer 104

Derived from pocket on the oesophagus​ Some fish retain connection via pneumatic duct (physostomous)​ Physoclistous fishes (incl. higher teleosts) have a closed bladder ​

Question 105

(Swim bladder) Some fish retain connection via pneumatic duct: physostomous. What is this?

Answer 105

​Physostomes release gas directly via the pneumatic duct which acts as a resorptive area​ slow vs quick​

Question 106

Physoclistous fishes swim/gas bladder?

Answer 106

Physoclists must release gas via the blood​ The bladder is poorly vascularised and lined with guanine crystals so impermeable; only a small part (the oval or ovale) acts as a resorption zone​ Blood carries excess gas away, and regulation is by muscles around the resorptive area

Question 107

Upon descent, increasing pressure shrinks the (Swim) bladder, so gas must be added. In shallow waters, physostomes can gulp air while in deep water they use physoclists. Another specialised region of the bladder (the gas gland) allows for diffusion of gases from the blood​. But… how can this happen?

Answer 107

​ 1. The Bohr effect causes unloading of oxygen from blood when pH decreases​ 2. Reduced solubility of gases when lactate and H+ increase (‘salting-out’ effect)​ 3. Efficiency of counter-current exchange in the ‘rete mirabile’ – bundle of capillaries around the gas gland 4. Combination of all three

Question 108

Why do deep sea fishes have relatively larger retes and migratory fish undergo physiological change due to their swim/gas bladder?

Answer 108

Tissues of gas gland undergo anaerobic respiration​ Results in high levels of lactate and H+​ Therefore a decrease in pH​ Build up of oxygen and other diffusible gases in the blood solution rather than bound to haemaglobin

Question 109

Pelagic sharks have largest livers and contain the most oil. This is instead of a swim bladder. Why?

Answer 109

​ Liver tissue has an average density of 0.95 g ml-1​ ​ With the liver removed the tissue density of a shark is ~1.06-1.09 g ml-1 (water is 1 g ml-1)​ ​ With liver included, mean density falls to approximately 1.007 g ml-1​ ​ A 460 kg tiger shark therefore has an effective mass in water of ~3.5 kg!

Question 110

Why may some fish not have swim bladders?

Answer 110

- Fatty liver - Fatty blubber - Skeleton composition

Question 111

How has form and function evolved to compensate for the challenges in the epipelagic (surface, open water) character?

Answer 111

Near-surface character: Open water systems, Lack of refugia from predators​, Within euphotic zone​, Need to maintain position in the water column​, No hard surfaces​. Resulted in convergent evolution of body form among unrelated pelagic fishes​ Narrower range of body forms and colouring than in many other systems​ Most pelagic oceanic fish:​ Have fusiform (hydrodynamic) bodies​ Are active visual predators​ Have strong countershading​ Have a mouth orientated upwards (superior) or to the front (terminal) to permit feeding from the water column​ ​

Question 112

Characteristics of most pelagic oceanic fish?

Answer 112

Have fusiform (hydrodynamic) bodies​ Are active visual predators​ Have strong countershading​ Have a mouth orientated upwards (superior) or to the front (terminal) to permit feeding from the water column

Question 113

How has form and function evolved to compensate for the challenges in the mesopelagic (surface, open water) fish character?

Answer 113

Vertical Migrators: - Swim bladder - Well-developed bones - Well-developed muscles Non-migrators: - No swim bladder - Weak bones - Flabby muscles Both share: - Black/black-silver colour - Large eyes - Large mouth - Photophores (can produce their own light) - Small body size (VM = 10cm. NM = 15cm)

Question 114

How has form and function evolved to compensate for the challenges in the bathypelagic (surface, open water) fish character?

Answer 114

- Head + jaws dominate (tend to orientate upwards), but often globular in shape - Weak, flabby muscles - Small eyes / absent - Lures to attract prey towards their mouthpart - Mostly red in colouration (but appear black at depth) - Small in size

Question 115

How has form and function evolved to compensate for the challenges in the Abyssopelagic (surface, open water) fish character?

Answer 115

- Evolutionary factors to rest on the bed of the ocean - Relatively large - Elongated - Small eyes - Strong muscle - Dark brown / black

Question 116

Body form of marine organisms are responses to what sort of pressures?

Answer 116

Evolutionary pressures

Question 117

What is the most successful fish taxon?

Answer 117

Teleosts (Teleostomi) Represent ~95% of all fish, most numerous group of vertebrates, immense diversity of forms and function

Question 118

General skeleton of teleosts?

Answer 118

- Cartilage is lighter than bone - Helps keep Chondrichthyes from sinking - Allows tighter turn radius - Allows great flexibility, but little fine-grained precision in skeletal structure - Reduced adaptive scope hence narrower range of body forms in comparison to other fishes.

Question 119

What are scale features of a teleost compared to other fish?

Answer 119

Thinner, lighter cycloid and ctenoid scales replace the heavy dermal armour of primitive ray-finned fish. Some fish lack scales

Question 120

Explain the evolution of fins in teleost compared to other fish?

Answer 120

Changes in fins increased manoeuvrability and swimming speed: - Symmetrical, homocercal caudal fin allows increased speed - Change in angle of inclination of pectoral fin base

Question 121

What is the diversification of teleost fins, part of the evolutionary success of the teleosts?

Answer 121

Diversified for a variety of functions: - Camouflage - Communication - Lures - Complex movements - Hydrodynamics - Predator evasion - Attachment to habitat

Question 122

Locomotion is energetically costly in water, and so structure and function become inseparable to overcome burdens of the environment. What are the two types of cost, what structure are they linked to?

Answer 122

Frictional drag: Affected by smoothness of surface and surface area. Linked to mucus/overlapping scales. Inertial drag: Increases with speed and therefore linked to body shape.

Question 123

Explain the importance of mucus production across a fish body?

Answer 123

Multifunctional. - Reduces drag: 'smooths' over rough edges of scales - Gaseous exchange - Protection: defence, UV, toxins/parasites

Question 124

How do 'wings' maintain neutral buoyancy without a swim/gas bladder?

Answer 124

Have a positive attach angle, 'wing-like' pectorals. Such as billfishes, sharks, tunas (also slightly negatively buoyant)

Question 125

How do myomeres aid structure and function in fish?

Answer 125

Muscle blocks attach to collagenous septa attached to skin/bone Contractions progress from head to tail (Newton's third law of motions suggests contractions pushing back n a body of water produces a reactive opposing force, thrusting the fish forward and laterally. This is overcome by the fishes morphology)

Question 126

What does Newtons third law suggest about fish locomotion/myomeres?

Answer 126

Newton’s third law of motion suggests that the contractions pushing back on a body of water produces a reactive opposing force thrusting the fish forward and laterally​ Lateral movement overcome by morphology

Question 127

What is the caudal fin, how does this structure affect function?

Answer 127

(The tail) Structure reflects normal swimming speed of fish. Fast: stiff, lunate, narrow peduncle The deeper the fork, the more frequent sustained swimming. Most bony fishes (most teleosts) have homocercal tails: Main function is to thrust themselves forward and yaw

Question 128

What are features of the pelvic fins that aid function?

Answer 128

Variable in position: Ancestral bony fish and in sharks it has abdominal position. While in derived teleosts, it has a thoracic or jugular position. Used for steering / braking (pitch and yaw)

Question 129

What are pectoral fins, what do these aid function wise?

Answer 129

Typically located high up on the sides of deep body fishes. - 'wings' of sharks, etc - Stability and manoeuvrability - More rounded - Braking / pitch and yaw - Limited locomotion

Question 130

What is the functional role of dorsal and anal fins, working together?

Answer 130

Generally long on rover-predators​ stability / anti-roll​ Typically folded when bursts of speed required​ or positioned well to the posterior​ Also in anguillids or eel-like fish​ frequently unite with the caudal​ ​

Question 131

Explain characteristics of Swimming method: anguilliform?

Answer 131

Characteristic of flexible, elongate fish​ ​- whole body flexed in lateral waves for propulsion​ ​- flattened posterior improves efficiency​ - >one wavelength within body length​ - cartilaginous fishes (flexibility) and YOYs (ontogeny)​

Question 132

Explain characteristics of Swimming method: ostraciform?

Answer 132

- Named after the boxfish family​ ​- contraction of entire muscle mass on one side, then the other​ ​- oscillation of caudal fin: ‘sculling’

Question 133

Explain characteristics of Swimming method: carangiform?

Answer 133

- Named after the jacks​ - throw the body into a shallow wave (

Question 134

Explain characteristics of Swimming method: labriform?

Answer 134

-Named after the wrasses​ - Ray and membrane design of fins allows undulation of individual or pairs of fins ​ - precise movements​

Question 135

What are the classification of feeding habits for fish?

Answer 135

detritivores / herbivores / carnivores / omnivores​ ​euryphagous – mixed diet​ ​stenophagous – limited assortment​ ​ monophagous – only one sort of food consumed​ (Most classed as euryphagous carnivores)

Question 136

How does gut length give indication of the fishes diet?

Answer 136

- Convoluted gut package typifies species feeding upon detritus and algae​ ​- Carnivorus species have a simple shorter gut​ ​- those preying upon small organisms relative to own size have longer guts than those feeding upon larger organisms​ - Digestive area increased via spiral valve intestines​ ​

Question 137

Explain how fish jaws have developed over evolution?

Answer 137

Skeletal rods that supported gill slits in filter-feeding, jawless fish Bones of first gill arch became upper and lower jaws Finally, second gill arch became upper and lower jaws Gradual change to become hinged jaws Remaining rods disappear as gills assume respiratory function

Question 138

What do evolution of teleost fish show in terms of jaws?

Answer 138

Great diversification of jaw form and function, with differences between primitive and derives teleosts

Question 139

How do fish pull water into their mouth?

Answer 139

Preparation – increase in pressure, lifting mouth floor​ Expansion – max suction, negative pressure up to -800 cm H20​ ​cavitation – water vapour coming out of solution, forming small vapour-filled cavities​ Compression – pressure increases, opercular valve opens after jaws close​ Recovery​

Question 140

How does fish mouth structure enable increased attack velocity by ~40%?

Answer 140

Protrusion of upper jaw, 'pipetting' - pull items 25-50% of head length

Question 141

Explain how mouth structure differs in eels?

Answer 141

Have both oral jaw and pharyngeal jaw (which can be pulled forward and opened to help pull larger pray into their throat)

Question 142

True or false, fish mouth position depends on what type of zone/food the fish feeds on?

Answer 142

True

Question 143

What are the three major methods for capturing prey?

Answer 143

Ram/pump suspension feeding, suction feeding, manipulation

Question 144

How does the predation cycle relate to structure of fish?

Answer 144

Search: active vs passive Pursuit: Chasing vs deceit Attack and capture: engulfing the prey Handling: post-capture manipulation Digestion and assimilation: chemical and mechanical breakdown

Question 145

What are characteristics of Active searching of prey in fish?

Answer 145

Active searching: fish swims around, actively searching for food​ ​Use of all senses: vision, olfaction, gustation, hearing, touch, mechano and electro-reception​ Speculation searching​: Probe into potential hiding places​ Actively flush prey out via some disturbance (e.g. turning over rocks)​

Question 146

What are characteristics of passive searching for prey?

Answer 146

Passive searching: ​ ambush/sit & wait predators​ Buried by sediment or use of or camouflage (flatfish)​ Some passive water column predators just hang in water column (John Dory)​ Allow prey to habituate and/or make use of counter shading (sculpins)​ ​Most passive predators use vision to detect prey (elasmobranchs also use electroreception).​

Question 147

What are characteristics of a fish that pursuits its prey by chasing?

Answer 147

Sustained chasing​ Very streamlined, fins fit in grooves (e.g. tunas)​ Manoeuvring (esp. near shore)​ Big fins and broad tails allow quick braking, sharp turns​ Highly controlled swimming to catch prey in complex habitats​ Fast start predators​ Lie-in-wait predators; elongate bodies, fins far back on body​ Tradeoff: Very fast for short distances, but can’t maintain speed for long stretches (e.g. barracuda)​

Question 148

What are characteristics of a fish that pursuits its prey by deceiving?

Answer 148

Some deceivers use lures:​ - modified body part to mimic food for prey, e.g. 1st dorsal spine modified into a lure​ - predator’s body camouflaged​ - predator sucks prey in and holds them with backward facing teeth​ Others stalk prey ​: - approach prey head on and make use of disruptive colouration which disrupts outline or the outline of the fish’s head to delay predator recognition​

Question 149

Characteristics of fish that use attack methods to capture their prey?

Answer 149

- Attacks by overtaking prey with simultaneous mouth extensions and suction - Fast-start predators overtake and target preys centre of mass - Benthic ambush predators usually have an enhanced capacity to engulf prey - Other fish swim and feed of particulate prey either by ram filter feeding or eating individual prey

Question 150

How do predators separate which prey they want from the other school of fish?

Answer 150

- Improves probability of predation - Attacks on stragglers more likely to be successful - predators often attack those prey that are different within the shoal - Selection for morphological and behavioural uniformity withing shoaling species - Some mimic shoal members or nonthreatening species

Question 151

Why do fish use post-capture manipulation when handling their prey?

Answer 151

Aids ingestion and digestion, removal of spines, toxic skins, etc and reduces prey size. Large prey typically manoeuvred to go in head first, allows prey fins/spines to be depressed, reduced escape chance

Question 152

What are the morphological adaptations of fish to aid with handling prey?

Answer 152

Teeth​ Piscivores: needle-like teeth for holding or shredding prey​ Molluscivores: molar-like grinding teeth​ Planktivores: teeth typically reduced or even absent ​

Question 153

Determining prey and capture methods of fish are often predictable from dentition. What are some features of Piscivores teeth?

Answer 153

Long, slender, sharp. Triangular. Villiform, needle-like Caniniform, recurved, conical Cardiform, sandpaper Molariform, blunt conical (molluscivorous) used for plucking/rasping in conjunction with pharyngeals.

Question 154

What are pharyngeal apparatus that aid feeding?

Answer 154

Teeth or pads evolved from modified gill arches​ herbivores develop small papilliforms​ ​molluscivores develop robust molariforms​ Function to rake prey into oesophagous​ - reposition​ - immobilisation​ - crush & disarticulate​ - But impacts gape-limitation…​ ​

Question 155

How do gill rakers aid post-capture manipulation of prey?

Answer 155

- Prevent loss of prey through operculum - Gill raker spacing related to size of prey

Question 156

How do fish avoid detection from prey/predators?

Answer 156

Camouflage: mimicry, disruptive colouration Countershading: Colouration of fish opposite patterns of light in water Silver colouration: Confuses predators Transparency: usually larvae eg eels Shoaling (using numbers to avoid detection)

Question 157

How can prey evade pursuit?

Answer 157

Detecting predators by mechanoreception Morphological adaptations such as: spines, toxic skin/internal organs, make use of aposomatic colouration or behaviour Shelter: Structured environments, sediments, corals. Speed: Outswim the predator or fly (flying fish)

Question 158

How can prey prevent and deflect attack?

Answer 158

Morphological adaptations: spines Behavioural adaptations: group living Dilution effect: the probability of an individual being eaten decreases with larger group size​ Confusion effect: Predators become confused by so many prey that they switch targets too often to catch many prey Migration to deeper depths to escape day light then moving back up during the night. (may have limitations however eg colder water, lower reproduction rate, feeding chance, etc)​

Question 159

How can some fish discourage capture from predators?

Answer 159

Morphological adaptations: Body shape, morphology that limit capture efficiency Prey handling capacity limited by mouth size Conspicuous erection of pines when threatened

Question 160

How can some prey discourage the predator once captured?

Answer 160

Morphological adaptations:​ - Spines that lock in position to prevent ingestion​ - Thick skin​ - Detachable scales​ ​Mucus production:​ - Hagfish​ - Toadfish​ Toxicity/venom​ - Fugu​ - Weaverfish ​

Question 161

How can environmental factors impact predator, prey interaction?

Answer 161

Environmental factors will generally have negative impacts on both the predator and prey during an encounter, but the magnitude of these impacts will depend on the situation, species, and whether the fish is a predator or a prey ​

Question 162

Fish sense their world in diverse ways. While most have 'terrestrial' senses, they may also possess means to detect more unfamiliar stimuli. How?

Answer 162

Via sensory perception Such as water particle displacement / electrical currents via for example chemoreception

Question 163

How do fish use chemoreception for perception?

Answer 163

Olfactory and gustatory organs​ Terrestrial animals can distinguish between the two:​ - olfactory – stimulated by airborne molecules; sensitive and chemical-specific​ - gustatory – stimulated by contact with dilute solution​ ​Both types of organs in fish have similar sensitivities to contact stimuli of chemicals in water​ - distinguished by location of sensory receptor &​ processing centre​

Question 164

Where are olfaction receptors located? What are these?

Answer 164

typically located in olfactory pits​ these have incurrent and excurrent channels (nares)​ water flow induced by:​ - cilia​ - branchial movement - swimming​ Odour is perceived when dissolved chemical contacts olfactory rosette​

Question 165

How do olfaction communicate stimuli?

Answer 165

Stimuli communicated via lateral or medial divisions of the olfactory bulb to the olfactory lobe of the brain via the first cranial nerve

Question 166

Olfactory cues include what in different organisms: sharks and salmon?

Answer 166

- Cues imprinted upon salmonid presmolts and smolts - Klinotaxis for food detection in sharks.

Question 167

What is fish taste used for (Gustatory chemoreception)? Where are their taste buds located?

Answer 167

Gustatory chemoreception used for both food and noxious substances​ Taste buds located on several exterior surfaces as well as the mouth​ including: Skin, fins, barbels, palatal organs, gill rakers and archers.

Question 168

What is the acoustico-lateralis system in fish used for? What are its two main components?

Answer 168

1. Used for sensing: sounds, vibrations, water displacement 2. Two main components: inner ear, neuromast/lateral-line system

Question 169

What is otolithic stimulation?

Answer 169

Semi-circular canals: horizontal, lateral and longitudinal planes detected. Each contain fluid, inertia-sensing chambers As sound vibrations impinge on a fish it is displaced in the water. Inertia of comparatively dense otoliths causes a lag phase, this movement is detected by ciliary bundles in the macula Amplitude and phase motions are transmitted to the auditory brain and processed as sound

Question 170

How else, other than the acoustico-lateralis system can fish detect sound?

Answer 170

At higher frequency, amplitude of fish displacement decreases​ More energy required for otolithic stimulation​ Swimbladder provides acoustical transformation​ Weberian ossicles​ Cartilaginous fishes have well developed endolymphatic ducts often use exogenous materials​ as otolith substitute​

Question 171

Mechanoreceptors within the lateral line are similar to what?

Answer 171

auditory and equilibrium systems detect water movements​​ More active fish have greater percentage of canal neuromasts ​ ​Prey detection / obstacle avoidance​

Question 172

What are some of the lateral line extensions?

Answer 172

Superficial neuromast Canal neuromast: protection, high pass filter, amplification

Question 173

Do fish have electroreception to aid sound detection?

Answer 173

Electroreception is found in all extant classes of fishes​ Electroreception has likely evolved independently as it is present in distantly related lineages of teleost fishes with a distant, common non-electroreceptive ancestor ​

Question 174

How does electroreception occur in teleosts?

Answer 174

External pit organs which are connected to the external environment via canals filled with electrically conductive gel. Marine elasmobranchs have ampullae of Lorenzini (AKA electroreceptors)

Question 175

How is magnetic force field detection able to help fish?

Answer 175

Detection of extremely weak electrical currents can aid fish in prey location and migration. Eg Depolarisation/repolarisation of muscle, dorsal and ventral location of receptors moved across the earths N-S magnetic field should detect induced electrical fields.

Question 176

How do fish see, photoreception?

Answer 176

- The eye is the primary receptor site​ - Most vertebrates have eyes with similar properties​ ​- Fish have a cornea of constant thickness​ - no optical alteration​ - all light focussed at the spherical lens ​ - highest refractive in

Question 177

What are characteristics of fish vision?

Answer 177

Eye typically bulges: field of view arcs forward continues laterally to almost directly behind fish Alternating head movements of anguilli or subcarangiform swimmers with co-orientated eye movement eliminates blind spot

Question 178

Why do fish have a spherical lens?

Answer 178

Spherical lens is eccentrically located in the elliptical teleost eye thus, lens-retinal distance varies. Near-field vision in from, far-field vision to the side - coupled with binocular depth perception. - Pulled inwards by retractor muscles

Question 179

elasmobranch lens enabling vision?

Answer 179

tends to be flattened ability to dilate or constrict pupils. Optical accommodation accomplished by moving lens. - Pulled outwards by protractor muscles

Question 180

Where is echolocation located?

Answer 180

Modification of the former nostrils. Tend to be used by dolphins.

Question 181

What does echolocation tend to rely on?

Answer 181

Upon reflection and interpretation of echo from swim bladder (which produces the echo in fish).

Question 182

What is the melon, in terms of echolocation?

Answer 182

- Mostly comprised of adipose tissue - Thought to be important in impedance matching - Gradient of fat; wax esters in the middle denser than triglycerides at the edges - Focusses acoustic energy like a lens

Question 183

Explain the difference of echolocation in water versus in the air?

Answer 183

Echolocation in water = less energy, pulses travel further, reach target faster, echoes return faster. Provides long range information, sound attenuates more slowly in water too.

Question 184

True or false: Are there complications to sound detection by echolocation in water?

Answer 184

Yes! Fish make noise, Storms and rain may disrupt it, Human activity such as boats, drilling, etc.

Question 185

True or false: Each sensory receptor has different perception ranges?

Answer 185

True! Electrical perception <50cm Vision <100m Pressure <100m Smell >100m Hearing >1000m up to several km

Question 186

Changes in oceanic primary production is linked to changes with what?

Answer 186

changes in the network of global biogeochemical cycles influenced the geochemistry of Earth for >3 billion years.

Question 187

Geochemical evidence suggests what ~2.2 billion years ago?

Answer 187

, Earth's oxygen reached concentrations comparable to that found today as a consequence of oxygenic photosynthesis by marine unicellular algae, the phytoplankton​

Question 188

What does photosynthetic carbon fixation by marine phytoplankton in the contemporary ocean lead to?

Answer 188

formation of ~45 Gt of organic carbon per annum​ 16Gt are exported to the ocean interior

Question 189

Not only currents are important for increasing concentrations for carbon across the oceans, subsidies (connections) are also incredibly important. But what for?

Answer 189

for micronutrients stimulating production​ But this could block out light... so is therefore, intensity dependent.

Question 190

What is the microbial loop?

Answer 190

Carbon dioxide is taken up by phytoplankton, zooplankton eats the phytoplankton or sinks down the ocean zones. Bacteria decompose the phytoplankton or are consumed by zooplankton in lower oceanaic zones or sink further into the ocean. Zooplankton respire and excrete carbon and migrate between zones. Bactria also release carbon which is passed back into the atmopshere. - A carbon recycling loop.

Question 191

What does remote sensing mean?

Answer 191

Developments in satellite imagery now mean:​ ​- More extensive (space & time) coverage ​ - More detailed understanding of physical drivers​ - Hence more accurate global budgets​ - Reduced cost of monitoring​

Question 192

Where chemosynthetic primary production occur, what is it driven by?

Answer 192

Occurs usually in seeps and vents in the deep sea. Usually driven by bacteria

Question 193

What is Methanotrophy?

Answer 193

oxidation of methane via methanol to formaldehyde, formic acid & carbon dioxide

Question 194

Why are estuarines biogeochemical hot spots?

Answer 194

receive large inputs of nutrients and organic carbon from land and oceans to support high rates of metabolism and primary production​

Question 195

What are the different primary producers in estuarines?

Answer 195

- Phytoplankton, - Microphytobenthos (can contribute to planktonic production under resuspension) - Sea grass, saltmarsh plants, bacterial components (relative of habitat size, nutrients supply, degree of tidal mixing)

Question 196

What are the primary producers in coral reefs?

Answer 196

Most reef-building corals contain photosynthetic algae known as zooxanthellae

Question 197

How do corals and algae have a mutualistic relationship?

Answer 197

- Coral provides algae with a protected environment and compounds they need for photosynthesis - In return, algae produce oxygen and help coral remove waste - Zooxanthellae supply corals with: glucose, glycerol and amino acids

Question 198

What does the relationship between algae and coral polyp facilitate?

Answer 198

A tight recycling of nutrients in nutrient-poor tropical waters (Up to 90% of the organic material photosynthetically produced by the zooxanthellae is transferred to the host coral tissue)

Question 199

How may primary production in coral reefs suppress coral?

Answer 199

Nutrient subsidies may confer competitive advantage to plankton, which has both direct and indirect impacts (eg inorganic particulates blocking light, algae function prevention, nutrient decrease, etc)

Question 200

Trophic transfer of production can estimate abundance and diet of all consumers, how?

Answer 200

Stomach contents analysis​ Regurgitates​ Faeces, pellets​ Observation​ - This enables a food web to be built, showing trophic links between consumers and primary producers within the system

Question 201

True or false, food webs change over time?

Answer 201

Yes. As organisms get older and therefore gain size, functioning body parts, consumption of organisms also changes to fulfil their needs. Eg some juvinile fish may only feed on zooplankton and algae, but adults may only feed on small fish and molluscs.

Question 202

What is the pyramid of energy?

Answer 202

Producers, Primary consumer, Secondary consumer, Tertiary consumer (As consumption level increases, rate of energy flow decreases)

Question 203

What is consumer diet analysed? How can accurately quantifying diet be a problem for biologists in terms of bias?

Answer 203

Stomach contents analysis – count, weigh​ Regurgitates, faeces, pellets​ - All these methods are biased:​ Hard-bodied prey retained longer​ Regurgitation​ Consumption of microscopic prey?​ Only a snapshot of diet over ~1 day​

Question 204

How do we trace consumer diets using biochemical tools?

Answer 204

The chemistry (elemental composition) of consumers and their food varies in different environments​ A consumer’s tissues are synthesised from the nutrients and energy they assimilate from their diet​ You are WHAT (and WHERE) you eat

Question 205

How are biomarkers (tracers) useful to measure chemical composition of producers and consumers?

Answer 205

- stable isotope ratios​ - fatty acid compositions​ Measuring chemical composition of primary producers, predators and prey can enable quantification of diet and flow of nutrients and energy​ - SIA - assimilated proteins & lipids​ - FAA – assimilated lipids

Question 206

What can stable isotope ecology tool use be useful for detecting?

Answer 206

Physiology​ Trophic ecology​ Migration​ Behaviour​ Ecosystem function​ Evolution​ Individual ecology​ Microbial ecology​

Question 207

What are isotopes?

Answer 207

atoms of the same element that differ in mass number e.g. they have the same number of protons but different numbers of neutrons ​ Can be stable or radioactive

Question 208

δ13C of CO2 and primary producers different in air, fresh and sea water. Why do stable isotope values differ?

Answer 208

Fractionation differences (how easy is it to get CO2 into the cell)​ Differences in water chemistry (availability of other C sources)

Question 209

How are raw ratios o stable isotopes converted into delta values?

Answer 209

((Rsample / Rstandard) -1) x 1000 = Delta X X = 13c, 15N X = the ratio between heavy/light isotope

Question 210

How are stable isotopes useful as biomarkers?

Answer 210

Heavy stable isotopes often become concentrated (fractionated) following chemical reactions, including biological processes. As a biomarker they can be passed from producer-consumer / consumer-consumer by: - Photosynthesis​ - Assimilation​ - Excretion​ - Respiration​ - Nitrification​

Question 211

Samples with higher delta values versus lower delta values?

Answer 211

Samples with higher δ values are relatively enriched in the heavy isotope and are ‘heavier’​ Samples with lower δ values are relatively enriched in the light isotope and are ‘lighter’, aka depleted in the heavy isotope​ Convenient mnemonic for δ values, “higher heavier, lower lighter” ​

Question 212

Explain the saying "you are what you eat" in terms of isotope consumption?

Answer 212

- Prey is consumed by the predator - Prey is assimilated by the predator - Predator stable isotope values reflects "signature" of the prey

Question 213

What does spatial variation in isotope values reflect (you are where you eat)?

Answer 213

Reflects biochemical and physiological effects of ecosystem differences So in terms of marine organisms, isotope concentration would vary dependent on where in the estuary they’re living. Eg river plankton my be -31%, while marine plankton may be -21%

Question 214

What did Don Schell study?

Answer 214

Examined isotopic variation in zooplankton in Northern seas. Showed upwelling signal over Bering sea shelf (He also worked on Whale baleen - long term indicated a decline in baseline delta 13C and 15N over time. Likely reflecting reduced upwelling intensity.)

Question 215

How can isotopes be used for historical samples?

Answer 215

Recent decline in egg delta 15N and 13C During most of the Holocene penguins fed in high trophic foods recent switch to lower trophic krill. Timings if the soft coincides with rapid depletion of whales and seals from the southern ocean Removal of marine mammals from southern ocean thought to caused an excess of this swap in diet.

Question 216

Is SIA or GCA more expensive?

Answer 216

GCA is more expensive, (gut content analysis), therefore SIA is likely to be used more

Question 217

How can fatty acids be used as bio markers?

Answer 217

Carbon rich compounds that are found in all organisms and the primary constituent of most lipids. Important molecules: - provide energy resources and essential nutrients for survival and growth - Integral components of cell membrane structure and function Show taxon-specificity: enables diagnostic Transferred from primary producers to higher trophic levels without major change as they generally remain intact throughout digestion, absorption and transport. Fatty acid pattens in prey or diet items can be used to study the diets of higher trophic level predators

Question 218

How can we tell if an organism has consumed fatty acids as a part of their diet?

Answer 218

Bacteria and phytoplankton have ability to synthesise complex fatty acids from simple chains, so if found in higher organisms, consumption of these smaller organisms must have occurred.

Question 219

True or false, Climate change is affecting marine and estuarine habitats and organisms?

Answer 219

TRUE!

Question 220

What are Anthropocene impacts on marine and estuarine biology?

Answer 220

- Climate change causing: - Temperature rise (causing unleashing 'expansion' of species, declining of others) - Coral bleaching (also due to temperature rise) - Loss of ice (eg in the Artic) which impacts species that habilitate it (eg polar bears, emperor penguins) - Sea level rise which may risk costal areas and cause 'costal squeeze' which will drastically alter edge habitats - Eutrophication stress

Question 221

How are polar bears and penguins impacted due to climate change and loss of ice?

Answer 221

Polar bears: Changes in foraging, prey-base, increased competition, reduced production and higher conflict​ Emperor penguins: 4/5 breeding colony failure in Bellinghausen Sea in 2022​

Question 222

What will costal squeezing due to anthropogenic activity cause?

Answer 222

Loss of buffering habitats such as: mangroves, sea grasses, saltmarsh Altered runoff characteristics from land, Increased nutrients and pollutants

Question 223

What will happen due to eutrophication stress due to anthropogenic activity?

Answer 223

Loss of buffers to filter outputs from intensification of agriculture​ Nutrient and soil loss ​

Question 224

What are red tides? Why are these increasing?

Answer 224

Increasing due to eutrophication stress Increasing in frequency and duration around the Florida coast as a result of nutrient loading. It can be toxic to marine life but now also linked to further acidification

Question 225

What ercentage of coral reefs world-wide are at high or medium threat from inland pollution and soil erosion?

Answer 225

~22% (25 years ago, so probably more now) Combined with bleaching. Recent estimate: 1tn$ cost, Ecosystem services, Tourist industry

Question 226

What are combatting coastal squeeze areas called?

Answer 226

Managed realignment sites

Question 227

What is known as the 'evil twin' of climate change?

Answer 227

Ocean acidification

Question 228

Why is ocean acidification worrying for marine and estuarine habitats?

Answer 228

Ocean pH already decreased by 30% If we continue emitting CO2, by 2100, acidity will increase by 150%

Question 229

What are the ramifications of ocean acidification?

Answer 229

Calcium carbonate saturation significantly reduced, particularly at polar and hypoxic borders Loss of 'shell-like' skeletal structure (coccolithophores are very important for photosynthetic primary producers) - If marine algal structure impacted, could affect pelagic, benthic coupling

Question 230

What is the predicted percentage of seabirds that will have ingested some plastic by 2050?

Answer 230

99%

Question 231

What has over-fishing lead to?

Answer 231

Reduction in diversity, Reduced fish size as we have fished the big fish too much! (titled: fishing down the food web) Knock-on effects on plankton Removing higher predators (potential to induce trophic cascades)

Question 232

Over-exploitation of orange roughy fish (Hoplostethus atlanticus) has caused what?

Answer 232

Orange roughy, Hoplostethus atlanticus​ Deep sea fish​ Age at maturation varies 23-40 y​​ (so take a while to reproduce) Very susceptible to recruitment overfishing​

Question 233

Aquaculture production has lead to what?

Answer 233

- Destruction of marine habitats such as mangroves - Reduction of wild fishing BUT questionable morals and overexploitation of other fisheries such as salmon, anchovies, etc - increases disease and parasites which can transfer into wild populations