Eutrophication of coastal systems 1.Our evolving conceptual model of the coastal eutrophication problem; James E.Cloern; Submerged aquatic vegetation in relation to different nutrient regimes; Carlos M.Duarte; Eutrophication and zoobenthos dynamics; Carlo Heip; 1995

Main research question Phase I Phase II Phase III

Main research question ; How does the anthropogenic nutrient enrichment cause change in the structure or function of nearshore coastal systems.

Phase I Model 1 Signal 1 response –Nutrient loading –more phytoplankton biomass, Primary production, Oxygen concentrations.

Phase I Model Vollenweider-type model

Reliability of the model Limiting nutrients Sediment traps Results gathered from temperate latitudes Weak signal between signal and response

Advances beyond Phase I model Understanding of 1 signal 1 response. Data gathering (no experiments).

Advances beyond Phase I model Responses in the Sediment Anoxia Release of phosphate Inhibition of nitrification

Advances beyond Phase I model Responses of fauna Step wise change from slow growing plants to fast growing algae.

Advances beyond Phase I model Responses of fauna From nutrient limitation to light limitation. Nutrient availability Resuspension of the sediment

Advances beyond Phase I model Responses of zoo benthos dynamics Pearson Rosenberg model –Slight increase of biomass. Slight change of species composition –Strong increase of biomass, replacement by opportunistic species –Disappearance of benthic animal species and azoic sediments

Advances beyond Phase I model Responses of zoo benthos dynamics Bioturbation Nutrient regeneration

Advances beyond Phase I model Importance of more nutrients like P or Si. Changing redfield ratio Toxic algal communitities. Recovery of the ecosystem

Advances beyond Phase I model Early responses to enrichment. Communities changes at species level. Nutrient cycling. Change in seasonal timing

The Phase II model The major differences 1.A more clearer picture of potential responses to nutrient enrichment 2.Recognition of system attributes acting as a filter for responses to change in nutrient loading 3.The possibility to reverse some of the direct and indirect responses of increased nutrient loading

The Phase II model

The Future Problems to solve Nutrient enrichment is thought as operating as an independent stressor Limited experimentation and modeling results Results mostly from highly impacted regions at temperate latitudes

A Phase III model

1.How does the filter work Tidal currents Salinity gradients Horizontal transport processes Light exposure to submerged plants Particle filtration by suspension feeders

A Phase III model 2.How does nutrient enrichment interact with other stressors 3.How are responses to multiple stressors linked Climatic system Human manipulation of coastal hydrology Human translocation of organisms Interaction between nutrients and toxic contaminants.

A Phase III model 4.How does coastal eutrophication impact the earth systems as a habitat for humanity Fishery losses Eating of polluted fish Methyl bromide or DMS production contributing to ozone depletion and acidification.

A Phase III model 5.What synthetic tools can guide management strategies. Restore the function of coastal ecosystems Protection of coastal systems A model as accurate as possible

A Phase III model Things to do Construction of nutrient budgets Development of indices to measure sensitivity Experimentation with representations of coastal systems