Ponsatí, Lídia; Barceló, D; Freixa, A; Guasch, H; Petrovic, M; Picó, Y; Corcoll, N; Ricart, M; Romaní, A.M; Tornés, E and Sabater, S.

Pollution in Mediterranean watersheds

• Seasonality and variability in rainfall.• Hydrology: floods and drought• High human pressures.

• Pollution for priority and emerging compounds

Epilithic biofilms:

• Epilithic biofilms are subject to river characteristics and respond veryquickly in front stress conditions.

Complex entity

Hypotheses:

Aims:

• Analyze the effects of chemical pollution in epilithic biofilms in Mediterranean watersheds.

• Understand the relevance of chemical pollution and environmental stress in structure and functioning of Mediterranean river biofilms.

• Environmental stressors explain the majors changes in biofilm structfrom headwaters to downstream.

• Chemical inputs affect efficiency in biofilm functions.

• Gradient of water quality decrease from EBRO – JÚCARGUADALQUIVIR – LLOBREGAT.

Study sites and samplig

5 sites in the main course acrochemical gradient –Autumn 20

LLOBREGATLLo3_Pont de VilomaLLo4_CastellbellLLo5_AbreraLlo6_MartorellLLo7_St Joan Despí

BRObr1_Reinosabr2_Mirandabr3_Harobr4_Mendaviabr5_Tudela

JÚCARJuc1_HúelamoJuc2_CuencaJuc4_MotillejaJuc6_AntellaJuc7_Alzira

GUADALQUIVIRGua1_MogónGua2_BaezaGua3_MarmolejoGua4_Córdoba

Physical and Chemical variables:

Pollutants analysis:

• Discharge (Q)• Conductivity (cond)• pH• Oxygen (O2 mg·L-1)• Temperature (TºC)

• Nutrient content• DIN (mg N · L-1)• TP (mg P· L-1)

• DOC (mg C · L-1)

Epilithic Biofilms:

Algal Biomass (Chl-a)Diatom composition (PCA cores)Photosynthetic efficiency

‐ Bacterial density‐ Extracellular enzymatic activity:

• Alkaline Phosphatase (AP)

St ti ti l l i

LLOBREGAT 4948.3kmLLOBREGATWater analysis: Nutrients and Conductivity

EBRO

Water analysis: Metals

Water analysis: Organic Pollutants

9166 n

Biofilm analysis

EBRO

LLOBREGAT

Biofilm analysis

GUADALQUIVIR

JÚCAR

Multivariate statistical analysis (RDA): Diatom responses

ance partitioning

3 groups

7.9%

OrganiccompoundsPhysical & 

Chemical

Non explained51.9%

Explained variance48.1%

‐Pharm‐ED’s8.1%

‐Q‐Cond12.4% 4.8%

2.5%9.5%

Multivariate statistical analysis (RDA): Biological response

riance partitioning

2 groupsPhysical

and Chemical:

Organiccompounds

16.9%Non explained

38%

Explained variance 62%

-Q4.1%

-Pest-Pharm

41%

• The most polluted system was Llobregat River, for metals and organic pollutants

• In general, Biofilms response to pollution is related to watershed land uses.

• Agriculture in Júcar

• Industrial and Urban in Llobregat

• Diatoms community distribution is explained for both stressors (environmental and chemical) but mostly for discharge and conductivity (upstream to downstream).

• Biological parameters are significantly explained by organic pollutants (Pesticides and Pharmaceutics)

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