All Flashcards
What marine habitat hosts a disproportionalety large fraction of productivity?
Coastal and marginal seas
Roughly, what proportion of the worlds population lives within 100km of the coast?
40%
What anthropogenic activities have a detrimental effect on marine life and habitat properties?
Recreation Extracting mineral & biological resources Transport Waste disposal etc.
What is the rough lenght of the Uk and Europea coastline?
~20,000km
~170,000km
What conceptual attributes did Costanza point out that a definition would require?
- Homeostasis
- Adsence of disease
- Diversity or complexity
- Stability or resilience
- Vigour ot scope for growth
- Balance between system components.
What do the consequences of an applied stressor depend on?
Where the pollutant is active within the organism (a giver stressor could have effects at different levels which may not cause death, but could be less functional).
What is the difference between synergistic and antagonistic effects?
Synergistic - the combined effect of two chemicals that combined cause a worse reaction greater than the sum of the individual reaction.
Antagonistic - the combined effect of two chemicals that have opposite effects.
When is a stressor an effect vs when is it a response?
Things can be both a stressor and a response. Distinction can be made on whether or not a driver can be actively managed. Wider context is important when categorising habitat quality.
What is a reference condition?
Pre-established criteria that exist for a wide range of representative sites and/or have been gathered over time as a baseline.
Who suggested a similar diagnostic procedure to the medical profession for assessing habitat quality?
Steevens et al.
Why do most assessments of macrobenthos as the candidate organism?
- Generally sedentary.
- Lifespan allows community structire to integrate and reflect sources of stress over time.
- Many species reside at the sediment (Where pollutanats concentrate).
- Taxonomically diverse.
- Model of sucession provides understanding of how benthic communities work.
- Methods of sampling have proven history.
What researchers contributed to the model of succession?
Rhoads-Pearson-Rosenberg-Gray
Who came up with the hierarchy of enviornmental parameters (and sum it up)?
Muller et al.
Each level of environmental objectives requires a corresponding set of environmental indicators.
What are the three elements of Ecological integrity?
Physical
Biological
& Chemical
What is the definition of holistic?
the belief that the parts of something are intimately interconnected and explicable only by reference to the whole
When does a substrate become a habitat?
When the intricacies of organisms are added
What is the Index of Biological Integrity and who was it conceived by?
Designed to describe the condition of streams (in central Illinois), by James Karr.
Roughly how much of the planet is covered in ocean?
70%
How much area does the seafloor take up?
360,000,000km2
How do sedimentation rates vary in different systems?
- Deep oceans - 0.5 - 1.0 cm 1000 years
- Contrinental margins, 10-50cm 1000 years
- some bays & deltas >500cm 1000 years
What is the average sediment thickness?
500m
Is the sediment in the atlantic or the pacific thicker and why is this?
Sediment thickness in the atlantic is around twice of pacific because major rivers flowing into the Atlantic extend over more land and carry a greater sediment load.
What is the most important factor in determining sediment thickness?
Time
What is the equation for sediment thickness?
sedimentation rate x time for accumulation.
What is the dictionary definition of a sediment?
Matter composed of particles which fall by gravitation to the bottom of a liquid
What are the 5 phases of a sediment that Paterson & Hagerthey provided?
- Mineral
- Vital (living)
- Non-living organic
- Free aqueous
- Gas
What are the 4 tpes of sediment?
Lithogenous, biogenous, hyrogenous and cosmogenous
how much of the sediment does lithogenous sediment make up?
75%
What are lithogenous sediments made up of?
derived from rocks
What are biogenous sediments made up of?
rementants and fragments of organisms
What are hydrogenous sediments made up of?
Inorganic precipitates
What are cosmogenous sediments made out of?
Cosmic derived, extraterrestrial origin. Silicate (like mantle), metal (like core) or both
What scale is the default description of marine sediments?
the Udden-Wentworth.
When do sediments flocculate?
Conditions where small charged particles become attatched and form a fragile structure, a floc.
What type of particles behave independently?
Large particles, they require more energy to move.
At what size do particles stop behaving independently?
63 microns
What problems can too much sediment deposition cause?
can physically smother habitats and physically alter morphonlogy of the benthos.
What problems can little much sediment deposition cause?
Can lead to nutrient depletion.
What are the properties of sediments, their distrubtion and composition linked to?
Biodiversity, habitat quality, and ecosystem integrity.
What factors will affect the sampling methods used?uestions that the study
- Nature & patchiness of target species and/or habitat.
- Practical considerations
- Questions that the study will address.
- Economic considerations
- Previous adopted practice
What are the four stages of deploying sampling gear?
- preparation of the gear
- deployment
- processing of the sample
- post-deployment processing of your samples
What are the size classifications of organisms?
- Microfauna, 63um
- Meiofauna, 63 - 500um
- Macrofauna, 500um -3cm
- Megafauna, > 3cm. (Identifyable in images)
Are trawl and dredge nets quantitative?
No (Length of tow can be measured to give a semi-quantitative estimate).
What type of transport is typically responsible for the greatest volume of sediment movement per anum?
Water
What is the mean depth of the mixed layer or bioturbated zone based on evidence collated from the primary literature?
8.37
According to Peterson, what were the two most important traits of a classifying species?
- Constancy
- Dominance
(He was attempting ot find characters that would determine a location, so its important that species were not seasonal or rare).
The process of gentle agitation of a sieved benthic sample using a continuous stream of water to wash away the fine material is referred to as…?
Elutriation
Who summarised the evidence in support of benthic successional models?
Pearson & Rosenberg, Rhods and Rumohr
How do soft bodied invertebrates burrow into sandy sediments?
- Inflate part of their body
- Probe the sediment
- Longitudinal muscle contraction
- Rhythmic movement
What are many of the adaptations seen on sediment environments driven by?
Cohesive nature of sediment
What do aggregations of dead Corallinaceae form?
Maerl
What words can sands be described as when water passes through and grains become suspended in pore water?
Thixotrophic
Who developed the concept of parallel communities?
Thorson
What is a parallel community?
If you travel to different parts of the world, communites often have the same structure, just with different species.
What is the phenomenon called when the differences in similar species whose distributions overlap are maximised in areas where they co-occur, and are minimal/absent when they don’t overlap?
Character displacement
Who developed the theory of ecological character displacement?
Brown & Wilson
What statements can be used to muddy environments?
- Relatively low energy habitats.
- Consisting of cohesive sediment
Where is the carbon compensation depth deepest?
Tropical regions
When are sediments classified as a biogenic ooze?
When at least 30% of the volume originates from a biogenic source
What kind of ooze forms in the Atlantic and why?
A calcareous ooze is formed, due to the fact that the water is ‘young’ and carbonate rich
What is a roughness velocity?
The velocity at whch laminar flow turns to turbulent flow
What is threshold velocity?
The current speed sufficent to move a particle
What is the settling velocity?
The settling point according to Stokes law
What is the ‘Leading edge’?
Where flowing water makes contact with a smooth boundary
What is a good example of a benthic sampling device that is not quantitative?
Dredge/trawler
What burrow teqnique/shape is most likely to be found in cohesive sediments?
U - shape
What is the RPD
Redox Potential Discontinuity boundary, amrks the depth at which sediment is 0mV when measured with an electrode.
What problems often follow when sampling the deep-sea benthos
- Replication of samples
- Low faunal densities and low survival
- Time to retrieve a sample
- Deployment failures
What are the three main evaporite minerals and what % water loss to they occur in?
Calcite/aragonite - 10%
Gypsum - 50%
Halite - 90%
What thickness can ocean sediments read at continental rises?
10,000m
Commonly, how thick is the sediment on mid-ocean ridges?
Barely anything
What is the main food source (by volume) in cohesive sediment?
Detritus
What is the main food source (by volume) in cohesive sediment?
Detritus
What is the physical mechanism that drives bioirrigation in non-cohesive sediments?
Advection
What is trophic group amensalism?
Rhoads & Young, Interactions between deposit feeders and suspension feeders. Suggested that the activities of deposit feeders inhibited the suspension feeders by causing the resuspension of sediment which clogged their filter feeding apparatus
What factors does tube building species in non-cohesive sediments create?
- Stabilise the local environment
- Alter the benthic biundary layer
- Generate suitable habitat for other species
- Enhance sediment deposition in the immediate area
What type of transport is typically found in muddy sediments?
Diffuse transport of fluid and/or particles (due to burrows having 2 openings)
What type of transport is typically found in sandy sediments?
Advective transport of fluid and/or particles (due to burrows typically having only 1 opening)
Why are sediment microbes the most biochemically important component of marine sediment biomass?
- They exhibit high population growth rates.
- They have high biochemical potential
- They have high surface area: volume ratio.
- They have the required metabolic versatility to oxidise organic carbon in a variety of ways
What is the removal of small organisms and surficial sediments as sampling gear approaches the sea floor reffered to as?
Bow wave effect
What are the benefits to trawls/dredges?
- Can cover wide areas
- Quick
- Can be deplyed in most weather conditions
- Good for collecting epifaunal organisms
What is the most common smapling methos for obtaining macrofauna inhabiting sediment?
Grab
Where are box samplers used?
Mainly used in shelf and deep sea regions, but can be used in shallower coastal waters.
Where are box samplers used?
Mainly used in shelf and deep sea regions, but can be used in shallower coastal waters.
What are the advantages of box samplers?
- Return relatively undisturbed large samples.
- Excellent for obtaning intact microbial, meiofaunal and macrofaunal communities.
- and undisturbed biogeochemical profiles.
- Retains the sediment-water interface, and overlying water.
What can be added to aid visual location of fauna at the sorting stage?
1% Rose Bengal stain
What is the minimum recomended time that samples should be stored for and why?
3 months, in order to stabilise the biomass.
What will the level of taxonomic resolution depend on?
On the objectives of the individual study.
What are the benefits to using Sediment profile imaging?
- Allows you to easily assess benthic habitat condition.
- Can observe subsurface macrofaunal behaviour.
What is SPI and who developed it?
Sediment profile imaging
Developed by Don Rhoads
Generalisations about SPI
- Prvoides a rapid, non-invasive means to observe invertebrate-sediment behaviour and interactions below the sediment-water interface, but images reflect the immediate environment in contact witht he face plate.
- Many interpretations from it have not been critically evaluated.
- Limited to soft-medium sediments, and deployment demands calmer weather conditions.
What is an AUV
Autonomous underwater vehicle. They are unmanned, untethered, battery powered robots with autonomous navigation abilities that can cerry sensing instrumentation and cameras.
What is a particularly relevant use of an AUV?
Unsertaking photographic surveys to provide detailed biological and habitat assessment
Disadvantages of AUVs?
- Relatively expensive, & require technical knowledge.
- Images often need colour correcting & calibration.
- Images are usually collected in the absence of additional environmental data.
What is the best methodology and approach to adopt?
It depends on the objectives of your study and whether you achieve the data you need to support/refute your hypothesis.
Who was the first person to bring assemblage ideas into preominence?
Petersen, one of the first to describe assemblages quantitatively based on characteristics of infanual communities.
What definition did Mills formulate that became a widely accepted definition of an assemblage?
“A group of organisms occurring in a particular environment, presumably interacting with each other and the environment, and separable by means of ecological survey from other groups”.
Why don’t dredges provide a representative sample of the faunal assemblage?
Because it is a selective sampler which doesn’t sample the whole assemblage.
What aspects of Peterson’s work the brought him into prominence?
- Developed a smaple retrieval method that could be samplised (Dredge).
- Had substantive amounts of data.
- Tested and developed his ecological ideas isign the data he had.
What ideas did Peterson develop using his data as the basis?
- Characterising species, assemblages could be described by these.
- Constancy and dominance were the most important features defining characterising species.
- Community definitions, defined 7 major community types.
What ideas did Peterson develop using his data as the basis?
- Characterising species, assemblages could be described by these.
- Constancy and dominance were the most important features defining characterising species.
- Community definitions, defined 7 major community types.
How many community types did Peterson define?
7
What did Petersons 7 major community types allow?
Allowed for 7 new community types to be recognised that could be easily referenced and understood by others.
What abiotic factors did bethic communities broadly match?
- Type of sediments
- Prevailing currents etc.
What question did Jones and Thorson develop following on from Petersons work?
Could the environemtn be the primary influence?
What limitations of Petersons work were identified by Jones?
” any system of classification should be based on the external conditions” and the literature did not present evidnce that assemblages were “bound together by biological factors”.
What did Jones suggest were the most likely factirs to affect distribution of communities?
Temperature, salinity & Sediment type.
Why was it discovered that parallel communites weren’t as widespread as initially thought?
The balance of evidence pointed to this not being the case. It was suggested that perhaps the methods were too simplistic, and many of the categories were quite arbitrarily defined.
Why can groupings of species be seen to be very different when different analyisies are used?
Because a single community can look very different when you are looking at is based on abundance compared to looking at biomass.
What were Thorson’s “Ideal rules”?
He drew up some standard units, standardising nomenclature and terminology and drew up specific acceptance criteria that allowed a binary yes/no decision as to whether a species would be classified as a characterising or not.
Why is there a focus on soft sediment habitats?
Because, in terms of spatial extent, cohesive and non-cohesive sediments are by far the most representative habitat of the benthos.
Why do organisms adapt to their environment?
- To respond to their changes in ecological or environmental context.
- To exploiy and derive sufficient resources, such as food or shelter/camouflage.
- To defend or protect themselves and their resources.
- To maximise chances of reproductive success.
What are the two types of adaptation?
Ecological and evolutionary
What is ecological adaptation?
Occurs within the lifetime of an organism; resulted from repeated exposure to a naturally occuring or lab/field-setting induced challenge.
What is an evolutionary adaptation?
Occurs within a population over longer time-scales (several generations); product of natural selection.
What is the difference between acclimation and acclimatisation?
Acclimation- non-heritable reversible modification that occurs over an individuals lifetime.
Acclimitisation - process by which an individual adjusts to a challenge in order to maintain performance across a range of challenging conditions.
What is the cost of a ‘plastic response’? (metabolic phenotypic plasticity).
They often require the reallocation of energy away from other important processes.
What is the main benefit to migration?
Individual/s can track favourable environmental conditions and/or resource avaliability.
Why do microphytobenthos migrate?
Downwardds in the sediment profile when ther is a high volume of water and there is a possibility of being washed away/grazed upon.
Upwards to the surface in order to photosynthesise.
What is the suggested theory for what triggers microphytobenthos behaviour?
Suggested that their movement is triggered by an internal rhythm.
Are there any microphytobenthos in non-cohesive sediments?
Only in relatively sheltered beaches.
What adaptations do species inhabiting physically dynamic habitats show?
Exhibit a range of adaptations that allow them to exploit resources.
What is a circadian rhythm?
Physical, behavioural & and mental changes that follow a 24 hr cycle.
Are deep sea benthos affected by seasonal shifts?
Deep sea benthos will respond relatively quickly to seasonal, inter-annual and decadal shifts in upper ocean variables.
What is the benefit of tubes to habitats?
The stabilise sediments and provide micro habitats.
What is character displacement?
Where differences among similar species whose distribution overlap geographically are accentuated in regions where the species co-occur, but are minimised or lost where the species’ distribution do not overlap.
What is benthic-pelagic-coupling?
Where the sediment-water interface have dynamic exchanges of energy, mass, and nutrients occur via a multitude of diverse pathways.
What are the 3 successive stages associated with Benthic-pelagic coupling?
- Deposition of non-living organic matter to the seabed.
- Mineralisation of material within the sediment.
- Release of nutrients back into the overlying water column.
What is the “biogenic alteration of sediments”?
Refers to the modification of the sediment habitat through the action of organisms that can obscure primary stratigraphic features and create other secondary structures.
On average, how much sediment did Davison estimate is brought to the surface by lugworms.
1911
What did Richter discover?
He improved the understanding of traces left by benthic fauna (fossils) and introduced the term bioturbation.
What is the difference between particle reworking and ventilation?
particle reworking - the movement or transport of sediment particles.
Ventilation - the movement or transport of interstitial porewater and solutes.
what ways can species facilitate the burrowing process?
Through the production of mucus, contraction/expasion of the body or hydrostatic skeleton.
What are the three main methods an animal can use to extend their burrow?
- Burrowing by fracture.
- Burrouwing by fluidise.
- Plasticallly rearranging.
What is burrowing by fracture?
Progress through the sediment by using a mechanically efficient mechanism refered to as crack propagation, whereby an alternating ‘anchor’ system of burrowing serves as a wedge to extend the crack-shaped burrow.
What is burrowing by fluidisation?
Burrowers deform the sediment by fluidisation.
What is burrowing by plastic rearrangement of sediment particles?
Example of a polychaete uses the curvature of its undulating body to rearrange particles within the sediment profile.
What is the method of choice when quantifying the redistribution of sediment?
To use particulate tracers.
What are the 7 modes of bioturbation?
- Epifaunal.
- Surficial modifiers.
- Biodiffusers.
- Gallery biodiffusers.
- Upward conveyors.
- Downward conveyors.
- Regenerators.
What is the correlation between microbal abundance and grain size?
Negative correlation
What are functional traits?
Those that define species in terms of their ecological roles
What is a trait?
Any feature at any level of organisation that is measurable at the level of the individual.
What is a functional group?
A set of organisms sharing similar responses to the environment and/or have similar effects on ecosystem processes and/or functioning.
What is the most important fact to do with defining characteristics for functional groups?
The distinguishing quality or characteristic used as a trait must have relevance to the species response or effect under study and be accompanied by supporting evidence as to its validity.
What should functional groups be?
- based on common attributes rather than phylogenetic relationships.
- incorporate interactions between organisms and their environment.
- relevant to interest or purpose of study
- accompanied by caveats
