The use of ASSETS and phytoplankton species The use of ASSETS and phytoplankton species composition to define type- -specific reference specific reference composition to define type conditions for estuarine water quality management conditions for estuarine water quality management ASLO/TOS 2004, Honolulu Session SS5.13 Eutrophication of Coastal Waters February 17 th 2004 http://www.eutro.org J.G.Ferreira T. Simas S.B. Bricker W.J. Wolff A. Mason A. Nobre
Topics Topics � Problem definition Problem definition � 1 � Monotype thresholds and problems Monotype thresholds and problems � 3 � Examples from a multitype world Examples from a multitype world � 4 Slides � Possible improvements to ASSETS Possible improvements to ASSETS � 3 � Conclusions Conclusions � 1 12+2 Guadiana estuary, Portugal
Problem definition Problem definition � Coastal eutrophication assessment has traditionally been based � on state � The NEEA approach developed a PSR framework, extended by � ASSETS into an integrated PSR, resulting in a single index � Overall Eutrophic Condition (OEC), the NEEA/ASSETS index for � state, is based on fixed thresholds � NOAA, EPA, OSPAR and others recognize that a fair assessment � of state should consider typology � Other regulatory instruments such as the EU WFD require the � definition of type-specific reference conditions
Typology reality check Typology reality check (a) regulatory reality (a) regulatory reality Stressors Natural (pressure) conditions (spatial/temporal variability) Frequency Thresholds Symptom level
ASSETS Monotype approach for OEC ASSETS Monotype approach for OEC (spatial/temporal variability) Stressors Natural (pressure) conditions Symptom 1 Frequency Spatial weighting Threshold Temporal weighting OEC Symptom 1 level (spatial/temporal variability) Natural Stressors conditions (pressure) Symptom 2 Frequency Threshold Spatial weighting Temporal weighting S.B. Bricker, J.G. Ferreira, T. Simas, 2003. An integrated methodology for assessment of estuarine trophic status. Ecological Modelling, 169(1), Symptom 2 level 39-60.
Classification issues Classification issues NEEA NEEA � Florida Bay: Highly sensitive system is severely impacted when � chlorophyll a reaches 5 µ g L -1 , which is considered Low by the NEEA category definition � Narraguagus Bay: Naturally occurring nuisance and toxic blooms � which come into the system from the ocean � NW coast: HAB events due to upwelling relaxation occurring � offshore, transported into the coastal bays and estuaries Others Others � Similar issues for HAB, e.g. in the Western Iberian Atlantic region � or the Benguela upwelling � D.O. thresholds set in absolute terms penalize water bodies with a � naturally lower capacity to dissolve O 2 , due to higher T and S � Short residence times or high natural turbidity favour shifts fr � Short residence times or high natural turbidity favour shifts from om pelagic to benthic symptoms of eutrophication pelagic to benthic symptoms of eutrophication � Use of means instead of medians or a percentile based approach � may misclassify systems subject to short extreme events
Typology reality check Typology reality check (b) ecosystem reality (b) ecosystem reality Stressors (pressure) (spatial/temporal variability) A A Natural C C conditions Frequency B B Symptom level Threshold A Threshold C
Dissolved oxygen in the Ria Ria Formosa Formosa Dissolved oxygen in the Channels and intertidal intertidal areas areas Channels and D.O in the channels D.O in the tide pools 300 300 100 100 90 90 No effluent loads (only ocean inputs) 250 250 80 80 Frequency Frequency Cumulative % Cumulative % 70 70 200 200 60 60 150 150 50 50 40 40 100 100 30 30 20 20 50 50 10 10 Cumulative % Frequency 0 0 0 0 O 2 (mg L -1 ) 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 More More 100 100 100 100 2X standard model (580 ton N y-1) 90 90 90 90 80 80 80 80 70 70 70 70 Frequency Frequency 60 60 60 60 Cumulative % Cumulative % 50 50 50 50 40 40 40 40 30 30 30 30 20 20 20 20 10 10 10 10 0 0 0 0 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 More 15 More Dissolved Oxygen (mg l -1 ) Dissolved Oxygen (mg l -1 ) Julian day
Long- -term (~70 years) series of phytoplankton term (~70 years) series of phytoplankton Long species species 80 A6 A7 A5 60 A4 Mondego 40 A3 A1 20 Diatoms 0 -150 -100 -50 0 50 100 150 200 -20 L. Óbidos -40 -60 Key -80 Other families Dinoflagellates -100 Chlorophytes -120 Prymnesiophytes A2 -140
Number of phytoplankton species as a Number of phytoplankton species as a function of water residence time function of water residence time 500 500 y = 14.79x + 122.6 Number of phytoplankton species Number of phytoplankton species 450 450 r = 0.93 r = 0.93 Sado Sado 400 400 p < 0.01 p < 0.01 Tejo Tejo 350 350 300 300 R. Aveiro R. Aveiro 250 250 Mondego Mondego 200 200 150 150 Guadiana Guadiana 100 100 Minho Minho 50 50 Species data: 1929-1998 0 0 0 0 5 5 10 10 15 15 20 20 25 25 Water residence time (days) Water residence time (days)
ASSETS multitype multitype approach for OEC approach for OEC ASSETS A, B and C are types Stressors Symptom 1 (spatial/temporal variability) (pressure) � Symptoms may be qualitatively type- A A Natural specific C Frequency C conditions � Quantitative or B B semi-quantitative symptom thresholds are type-specific Symptom level Symptom 1 Threshold A Threshold C Spatial weighting Temporal weighting Symptom 2 Stressors (spatial/temporal variability) OEC (pressure) A A Frequency Natural C C conditions Symptom 2 B B Spatial weighting Temporal weighting Symptom level Normalized scores are as before, but related to Threshold A Threshold C type-specific thresholds
NEEA/ASSETS chlorophyll a and HAB Frequency distribution according to required P max OEC Chlorophyll a OEC Nuisance and toxic blooms Frequency (% of each P max class) Frequency (% of each P max class) 70 120 60 100 50 80 40 60 30 40 20 20 10 0 0 <1.5 1.5-2 2-4 >4 <1.5 1.5-2 2-4 >4 Pmax required for phytoplankton to bloom in the estuary NEEA Grade 1 NEEA Grade 2 NEEA Grade 3
Residence time and species number Correlation and ranges 450 Number of species Nº species = 14.012T r + 137.78 Sado 400 r = 0.93 (p< 0.025) 350 Tejo Ria de 300 Aveiro 250 200 Mondego 150 Minho 100 50 0 0 5 10 15 20 25 Residence time (days) Species data: 1929-1998
Final Final comments comments � Natural conditions are widely variable, due to abiotic and bioti Natural conditions are widely variable, due to abiotic and biotic factors. This puts into c factors. This puts into � question the use of absolute thresholds for eutrophication symptoms; oms; question the use of absolute thresholds for eutrophication sympt � Eutrophication assessment currently relies on a PSR approach, th Eutrophication assessment currently relies on a PSR approach, therefore the distinction erefore the distinction � between natural and anthropogenic causes is critical, in order to define responses o define responses between natural and anthropogenic causes is critical, in order t (measures); (measures); � Natural variability may be translated into types, which will det Natural variability may be translated into types, which will determine the reference ermine the reference � conditions for eutrophication symptoms. Deviations from a type- -specific pristine specific pristine conditions for eutrophication symptoms. Deviations from a type situation will determine response; situation will determine response; � Assessment methods such as NEEA and ASSETS do already accommodat Assessment methods such as NEEA and ASSETS do already accommodate natural e natural � variability, by accounting for vulnerability and susceptibility, which are indirectly related variability, by accounting for vulnerability and susceptibility, which are indirectly related to typology (e.g. more vulnerable systems naturally have higher symptom expression); symptom expression); to typology (e.g. more vulnerable systems naturally have higher � Type Type- -specific reference conditions may be defined using (a) Pristine specific reference conditions may be defined using (a) Pristine systems (b) systems (b) � Historical data (c) Heuristics (d) Modeling; Historical data (c) Heuristics (d) Modeling; � Research models may be used to explore changes in state (impacts Research models may be used to explore changes in state (impacts) due to various ) due to various � pressure scenarios for different types, to help define meaningful thresholds. pressure scenarios for different types, to help define meaningfu l thresholds.
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