6 FUNCTIONAL GROUPS Flashcards
How organisms respond to various ecological factors and in turn how these responses affect ecosystem functioning is fundamental to discerning ecological what?
Ecological consequences of change
What do taxon based approaches compare? What do they often use? Why don’t identified patterns necessarily point to causation/provide mechanistic understanding from a functional standpoint?
- Compare species assemblage in relation to environmental conditions
- often using multivariate statistical approaches
- any identified patterns don’t necessarily point to causation or provide mechanistic understanding from functional standpoint bc taxonomic position of a species isn’t a reliable indicator of ecological role of species
What is the focus in trait based approaches?
- How the components of biodiversity influence ecosystem properties
- Therefore are touted as offering greater mechanistic understanding that can be applied more generally.
What are functional traits?
Those that define species in terms of their ecological roles; how they interact with the environment & other species.
What are biological species traits? What do they relate to?
The attributes of a species.
They relate to morphological, biochemical, physiological, structural, phenological, behavioural, and/or any other functionally relevant life-history features of the organism
What is a functional effect trait? What can they help us understand?
What is a functional response trait? What can they help us understand? What is functional redundancy?
- Any trait which alters specific community or ecosystem properties. They can help us understand organism-sediment interactions, how species effect ecosystem processes, and the delivery of ecosystem functioning.
- Any trait responding to external forcing that alters the performance or fitness of an individual, e.g. via its effects on growth, reproduction and survival. Can help us understand how communities may change in resp to environmental change.
- Functional redundancy = overlap in functional capability (several species contribute/respond in the same way as other species)
What is a functional group?
A set of organisms sharing similar responses to the environment (e.g. temp, salinity, nutrients, competition) / have similar effects on ecosystem processes (e.g. bioturbation) / functioning (e.g. productivity, nutrient cycling)
What is a good strategy for understanding effects of functional diversity on ecosystem processes?
Nesting functional response groups within functional effect groups
Unifies the processes of community assembly and biodiversity effects on ecosystem function.
What are some examples functional trait category/associated categorised trait modality pairings?
body mass -> biomass, biovolume or other size measurement
morphology -> shape, structure & network properties
larval type -> planktotrophic, lechithotrophic, direct development
living habit -> sedentary, errant, attached, tube or burrow dweller
activity -> periodicity (occasional, cyclic, continuous) or mode (e.g. bioturbation, reworking modes)
feeding habit -> detritivore, herbivore, carnivore, omnivore, scavenger, predator, parasitic
resource capture -> jawed, siphon, tentaculate, pharynx, radula
mobility -> sedentary, semi-mobile, mobile
movement -> byssus, swimmer, rafter/drifter, crawler, burrower
environmental position -> pelagic, epibenthic, benthic, physiological requirements
Why is size (typically biomass) not necessarily a reliable indicator of species functional distribution?
reflects a range of other factors, like life stage and recent environmental conditions.
How do tube building species/species with protruding physical structures act as sediment stabilisers?
How do species that disproportionately mix the sediment profile act as sediment destabilisers?
- act as baffles and redirect current flow, and large stands of species can raise the benthic boundary layer
- can increase porosity and erodibility of the sediment surface
What are the different functional feeding groups? (6)
- engulfer
- shredder
- piercer
- scraper
- collector
- filterer
What are the 6 trophic feeding groups?
suspension deposit carnivore omnivore herbivore
What are the 7 types of bioturbation?
- epifaunal
- surficial modifiers
- biodiffusers
- gallery biodiffusers
- upward conveyors
- downward conveyors
- regenerators
What is the difference between classification and ordination approaches to group species into functional groups?
Classification techniques: tend to assign species on assumed a priori defined species roles & tend to be based on evidence from lit & expert knowledge. Groups similar species based on assumed traits.
Ordination: studies tend to use continuous rather than categorical traits & identify functional group membership using statistical techniques based on measured data. Groups similar species based on measured traits.
What is the requirements of summary functional effect descriptors in order to be useful, but are rarely filled?
- need to have been derived using systematic selection process
- sufficiently comprehensive
- to provide acceptable explanatory power for observed species contributions to ecosystem function
What is an example of how species can appear to belong to the same functional group, when in fact being functionally distinct?
Resource partitioning
Diff bivalve species share same mode of reworking (surficial modifiers) and feeding mode (suspension feeding), but diff in body size and occupy v diff depths within sediment profile.
What is a commonly used marker of trophic position?
What is their advantage over gut content analysis?
Analysis of stable isotopes
They reflect tissue assimilation from prey
Aren’t hindered by stomach content biases
What is a commonly used marker of trophic position?
What is their advantage over gut content analysis?
Analysis of stable isotopes
They reflect tissue assimilation from prey
Aren’t hindered by stomach content biases
Why could the food availability hypothesis, regarding sandy and muddy sediments dominated by suspension and filter feeders due to food availability, be incorrect?
i) water column data revealed more organics in water column above mud, but still no suspension feeders
ii) boundaries betw suspension feeding and deposit feeding often too sharp to reflect food supply gradients
iii) hard substrata e.g. rocks in otherwise muddy sediments were not necessarily covered in suspension feeders
What did rhoads and young hypothesise regarding deposit and suspension feeders?
- deposit feeders negatively effect suspension feeders, excluding them from mud habitats
- showed relationship between high sediment turnover and high water content
Do deposit feeders increase erosion? Use the Rhoads and Young experiments to explain; they thought that deposit feeders may create much finer sediments that, in turn, would clog the filtering apparatus of suspension feeders.
YES
- greater resuspension leading to turbidity above the burrowed sediment than over the unburrowed sediment
- during erosion of loose granular sediment, roughness of the sed surface increased, producing turbulence, which accelerated the erosion process
Does sediment resuspension benefit suspension feeders? Think about growth of juvenile mercenaria mercenaria on trays at different elevations from seabed.
NO
growth of juvenile m mercenaria is inhibited near the unstable sediment-water interface
What is the trophic group amensalism hypothesis? Think about suspension & deposit feeding trophic groups.
What did their rationale include?
Rhoads and Young suggest that there are interactions betw suspension and deposit feeding trophic groups that lead to exclusion of one group over the other.
- deposit feeders create much finer sediments that clog the filtering apparatus of suspension feeders
- deposit feeders would consume settling larvae
- deposit feeders would cover any surfaces to which suspension feeders would attach
