aquatic restoration

marine systems

includes open ocean, deep sea ocean and coastal

freshwater ecosystems

lentic, lotic, wetlands

lentic

slow moving water

ponds, pools, lakes

lotic

fast moving water

streams and rivers

wetlands

areas where the soil is saturated or flooded at least part of the time

swamp, marsh, fen, bog, peatlands

degradation of rivers

sewage influx

land use intensification - increased sediments or ag runoff

physical degradation - habitat and channel alteration, drainage, flood protection, navigation, hydropower, etc

spatial and temporal scales of restoration

watershed level → whole river → reach → habitat / microhabitat

various activities at each scale

local scale depends on larger scale processes like climate change, urban waste, source populations, riparian zones, run off, barriers, straightening, etc

upstream barriers restrict restoration at smaller scales. linkages within a watershed at all levels

attributes of river reference ecosystems

channel patterns, width and depth variations, flow velocities, substrate conditions, structure and condition of the riparian zones

natural flow regimes are the most important drivers - but what does this mean?

ex Athabasca river

only unregulated river in the province

compared gauged flows from 1930s onwards, then compared to tree rings with predicted historic records

contemporary records show a pretty chill recent years compared to historic highs and lows → not representative

is this natural flows?? depends on objectives and study

common restoration interventions in Europe

channel connectivity - removing dams / obstacles for migration

channel planform - change to meandering course

habitat conditions - improving substrate conditions and water velocity variability

the easiest measures are most common, most difficult (naturalizing flow regimes) is least common

ecological purpose of dam removal

restore downstream spawning and rearing habitats, promote re-emergence of river channels and restore fish passage

dams block fish migration

removal also releases stored sediment which has short term negative impacts

Washington Elwha dam removal and restoration

restore ecological habitat, etc, other actions included hatchery production, fishing bans

goal to evaluate the trends in juvenile chinook salmon and trout, from natural or hatchery origins after dam removals

used variety of monitoring approaches

Washington Elwha dam removal results

high sediment reduced salmon populations initially, but recovered by 2018

estimated fish populations with redds, redds started to increase after dam removal

natural origin juvenile abundance increased after dam removal

proportion of hatchery salmon outweighs natural origin

counted redds upstream to watch fish move upstream

Washington Elwha dam removal conclusion

critical role of hatchery, natural reproduction was well below replacement, adults moving into recently opened habitats

too early to determine if population increases was due to dam removal

many management methods to increase population levels - lots of factors important

coral reefs

host high coral cover and recruitment rates, high fish biomass, and high algal grazing rates → biodiversity, shelter, nourishment of species

effects of climate change on coral health

higher sea level temperatures breaks the relationship between coral animal and endosymbionts - algae leaves and the coral becomes bleached

ocean acidification from CO2 in the water column increases energetic demands for calcifying organisms like coral - reduces bleaching tolerance

coral reef restoration - local scale

out planting coral colonies

substrate enhancement and construction of artificial reefs

releasing reared or harvested coral larvae

outplanting of coral colonies

coral colonies from source reef - seeds or propagules, either direct transplantation

note like regular seeds most of them are dying, not reliable → nurseries max success

proponents of local coral restoration

bridge the temporal gap between large scale action on climate change and the lag effects for indirect management actions
what is the cost of no action?

critics of coral restoration

the cost is too high and done on areas prone to failure (near human settlements) or heat stress due to climate change → preservation should be first

local restoration cannot be scaled up to protect global reefs from degradation

also risks diverting attention from the addressing the root cause

concerns with large dam removals

local communities likely to be affected - infrastructure destroyed, water quality concerns, land subsidence, loss of hydropower or economic concerns, increased flooding risk

cultural reasons behind dam removal

species present, revegetation, fish population size to support fishing, access of fishing, long term sustainability