Yallop - Biodiversty and ecosystem function Flashcards
how is the Water Framework Directive (EU, 2000) different to other management strategies?
Puts BIOLOGY at centre
Member States still need to work out chemical limits needed to support Good Ecological Status but final test is biology, not chemistry
studies: benthis macroinverts, macrophytes and phytobenthos, phytoplankton, fish, hydromorphology
what is RIVPACS?
River Invertebrate Prediction and Classification System
Computer system used to predict natural invertebrate fauna expected at a site
what is MTR and DARLEQ?
Mean trophic rank
way of measuring macrophytes.
Diatom Assessment of River and Lake ecological Quality.
these tools have given a good representation of river biota across the country.
Study of how species composition affect function of a water body
Cardinal et al 2002
Species diversity enhances ecosystem functioning through interspecific facilitation
studied Three species of Trichoptera (caddis fly larvae) that coexisit in streams in eastern US.
Hydropsyche depravata
Cheumatopsyche sp.
Ceratopsyche bronta
they are suspension feeders which construct silk nets in stream bed.
hypothesis: differenced in feeding structures of 3 species will affect Near-bed roughness, causing a change in water flow rates which may enhance food capture.
made stream mesocosms with either single (18 larvae) or mixed assemblages (3species x 6 larvae). measured consumption of suspended particulate matter and near-bed flow rates.
mixed has 66% more SPM consumption than single.
feeding performance of individual species enhanced in mixed assemblages in 2 of the species.
concluded 83% complementarity- as sp yields in polyciulture are on average higher than expected. 17% selection.
Suggests all 3 species increase heterogeneity and could enhance near bed flow rate. shading by upstream larvae lowers food delivery rate, more pronounced in single species streams, 22% faster in mixed species. this is evidence that macroinvert diversity affects ecosystem function.
what are selection efects on ecosystem functioning
where the dominance of one species with particular traits affects ecosystem process such as change of resource use
Can biodiversity affect water quality?
Cardinale et al 2011.
Evidence suggests that ecosystems that have more species are more efficient at removing nutrients. perhaps is biotic diversity downstream of sewage pipes was maintained it would help reduce input of N into lakes. greater niche partitioning.
experiment by cardinale et al to test in higher diversity can remove mor nutrients from water.
- stream mesocosms to see link between algae diversity, niche differences and rates of nitrate removal from stream water..
left 8 species of algae to colonise flumes.
Flumes either heterogeneous - 2 forms of environmental variation to allow expression of niche differences (bed roughness and disturbance - spatial and temporal heterogeneity)
homogeneous - uniform near bed velocity, no habitat disturbance.
lots of replicates required.
presence of algae within a patch depended on ability to colonise rapidly and compete w others
Biofilms matured and labelled nitrate added. Incubated and measured concentration of labelled N in the biofilms and biofilm biomass
found: if more species, greater Nitrate uptake in heterogeneous flume. rate reaches asymptote in homogenous assemblage.
concluded that sig effect of algal species richness on uptake of nitrate marked in heterogenous streams and no effect in homogeneous streams. suggests niche complementarity, species are using resources in unique or synergistic ways, whereas in homogeneous streams, system driven toward dominance by one species.
how do cardinale et al’s conclusions relate to eutrophication?
Biodiversity improves water quality through niche partitioning.
But, eutrophication causes a decrease in biodiversity so reduces the capacity of the system to make use of the extra nutrients
how might humans be driving rivers and streams towards monocultures?
example
overexploitation of freshwater systems, pollution, habitat destruction and degration.
Restoration programmes must consider introducing a variety of morphological forms that allow species to occupy unique and complementary habitat types in a stream, or lake.
problem of non indigenous species in the Rhine
major shipping route through the Rhine, bringing invasive species. ‘global highway’, about 45 species have invaded. increased by aquarium and aquaculture industries
dominated by molluscs and crustaceans.
Invasives may be able to tolerate fluctuating salinity and temp, and displace natives.
example of invasive species in the rhine
eg Corophium curvispinum: transfers coarse and hard surfaces to fine and muddy areas, smothers sessile orgs in thick layer of mud. soon declined, linked to consumption by D. villosus and comp for space.
Dikerogammarus villosus: now dominant and affects competition for space between two filter feeders. caused decline of other species.
Dreissena polymorpha
examples of huge lakes
Lauentian Great lakes, canada/us.
5 great lakes, water flows east to west, from St. Lawrence river and out to Atlantic.
Lake superior - deepest 1835m
Lake Huron and Lake michigan
LakeErie - most polluted, 19m deep, surrounded by industrial areas.
Lake ontario
what has caused pollution in lake erie?
surrounded by industrial areas.
Phosphorus loading increased as population increased substantially
ecology and biology of an invasive species in great lakes.
Walsh et al, 2016
Bythotrephes longimanus, spiny water flea - large cladoceran
parthenogenesis, and sexual rep.
naive to northern europe and asia, introduced accidentally to great lakes, possibly through ballast water. barbs and spines provide protection from predators.
eggs can survive dessication and passage through gut.
diet of daphnia and smaller cladocerans, 10-20 per day. competes w young panfish and perch for food. daphnia pops declined
presence coincident with decreases in species richness and abundance of several Cladocerans including Daphnia pulicaria and D. retrocurvata
where did Bythotrephes longimanus invade?
first Lake ontario, found in 1982
second Lake Mendota, much smaller, 2009.
