marine biodiversity and ecosystem functioning (marine lecture 2) Flashcards
What is ecosystem functioning? How is it quantified?
- processing of energy and materials
- rates of: primary and secondary production/respiration/decomposition/nutrient recycling/energy flow in food webs
What functional pathways does ecosystem functioning encompass?
- photosynthesis, nutrient fluxes/uptake, sediment mixing/stabilisation, clearance of particles from watercolumn
How to measure marine ecosystem functioning?
- function, measurement, organism
NPP: biomass: microphotobenthos, algae
nutrient fluxes: nutrient analysis: sediment infauna
bioturbation: luminophores: sediment infauna
movement: observation: sediment infauna
surface adhesion: magnetic particle induction: biofilms
decomposition: biomass: fungi, bacteria
algal standing stock: biomass: algae
secondary production: biomass: molluscs
What is bioturbation?
- the physical effect of animals, benthic (usually burrowing) macroinvertebrates, on their substratum
- reworking (sediment mixing): feeding, defecation, burrowing
- ventilation: gallery flushed by water: respiration, feeding
- bio-irrigation: water forced through sediment
- determined sediment oxygen concentration, influencing organism biomass, organic matter decomposition, nutrient regeneration, primary productivity rates
What are soft sediment communities?
- most of sea bed
- shelf sea ecosystems among most productive + diverse on earth
- benthic communities essential component of these ecosystems
- underpin v important nutrient cycling, fisheries etc
- threatened by human activities
How is bioturbation measured?
- sediment profile imaging
- pet/ct imaging
Sediment Profile Imaging
- luminophores = natural sand-based sediments treated w a fluorescent UV dye
- spread on sediment surface in situ/in lab
- SPI records vertical spread of fluorescent particles
PET/CT imaging
- measures ventilation, bio-irrigation
- CT = 3D structured info of biogenic structures (burrows)
- PET = 3D info on flow dynamics
How can individual measurements be scaled to ecosystem level?
- define ecosystem level metric relevant to ecosystem functioning
- e.g. biogenic mixing depth from in situ sediment profile images
- define biotic components that might influence metric
- e.g. predation, herbivory, parasitism, mutualism, competition
- use species traits to estimate species level bioturbation potential
- e.g. size, abundance, mobility, mode of sediment mixing
- combine w community survey data for community level bioturbation potential
What are the modelled effects of extinction on bioturbation?
- ecosystem function always declines with species loss in non interactive models and usually interactive
- extinction order matters
- individual species can be critical (e.g. A. filiformis, brittlestars)
Why should biodiversity be important for ecosystem functioning?
- increasing biodiversity increases chance of important function being delivered
- increases complementarity through functional redundancy
- can increase delivery of function by common species (e.g. fisheries production)
- increases chance important rare species are presence
Why is marine ecosystem functioning important for humans?
- while EF processes not directly important to humans, they underpin important ecosystem services
- nutrient cycling, climate regulation, fisheries, wildlife
