Community-level microalgal toxicity assessment by multiwavelength-excitation PAM fluorometry.

In ecotoxicological studies involving community-level investigations, rapid and multiparametric fluorescence-based methods may provide substantial advantages over traditional methods used for structural and functional community analysis. Therefore, multiwavelength-excitation pulse-amplitude modulated (PAM) fluorometry was applied in this study to assess long-term changes in periphyton community structure, short-term effects on periphyton functioning (photosynthesis) and pollution induced community tolerance (PICT). For inter-calibration, periphyton structure was evaluated by chemotaxonomic analysis of accessory pigments and a four-wavelength-excitation PAM fluorometer. Short-term effects of herbicides were evaluated by fluorescence quenching analysis and (14)C-incorporation as a proxy of primary production. Subsequently, the method was applied to assess structural and functional changes in periphyton communities after isoproturon exposure for 14 and 26 days, respectively. Results showed good correlation of the PAM fluorescence-based measurements with traditional methods for biofilms in the initial colonisation phase for structural and functional parameters. However, for biofilms older than 9 weeks PAM fluorescence may underestimate biomass. Multiwavelength-excitation PAM fluorometry showed good correlation with marker pigment concentrations indicating that this method provides a reliable estimate of the community structure. PAM fluorometry was able to quantify changes of biomass and follow relative shifts in class composition of biofilms under exposure of isoproturon. Short-term tests based on the quantification of the inhibition of the effective quantum yield revealed a concentration-dependent increase of PICT. The observation of two succession phases of the biofilms after 14 and 26 days of growth, respectively, revealed that sensitivity of biofilms decreased with increasing age and biomass, respectively, but PICT remained a characteristic parameter of exposed communities in a concentration-dependent relationship. In conclusion, multiwavelength-excitation PAM fluorometry has considerable potentials in multispecies and multiparameter assessment of toxic effects on community level in terms of (1) a combined and rapid evaluation of structural and functional parameters in parallel, (2) screening of trends over time, (3) observing effects in replication and (4) being non-destructive. The approach therefore provides a perspective for a better understanding of community-level effects as species interactions in terms of PICT and therefore a higher ecological realism in risk assessment of toxicants.

[1]  A. Boudou,et al.  Effects of the phenylurea herbicide isoproturon on periphytic diatom communities in freshwater indoor microcosms. , 1996, Environmental pollution.

[2]  T. Backhaus,et al.  The SWIFT periphyton test for high-capacity assessments of toxicant effects on microalgal community development , 2007 .

[3]  Rolf Altenburger,et al.  Development and validation of a new fluorescence-based bioassay for aquatic macrophyte species. , 2007, Chemosphere.

[4]  C. Moldaenke,et al.  "Spectral fingerprinting" for specific algal groups on sediments in situ: a new sensor , 2006 .

[5]  John Moncrieff,et al.  Photosynthesis: from Light to Biosphere , 1995 .

[6]  C. Leboulanger,et al.  A pulse-amplitude modulated fluorescence-based method for assessing the effects of photosystem II herbicides on freshwater periphyton , 2001, Journal of Applied Phycology.

[7]  U. Schreiber,et al.  New type of dual-channel PAM chlorophyll fluorometer for highly sensitive water toxicity biotests , 2004, Photosynthesis Research.

[8]  R. Altenburger,et al.  The use of pulse-amplitude modulated (PAM) fluorescence-based methods to evaluate effects of herbicides in microalgal systems of different complexity , 2007 .

[9]  K. Solomon,et al.  Creosote toxicity to photosynthesis and plant growth in aquatic microcosms , 2003, Environmental toxicology and chemistry.

[10]  H. Dau,et al.  A fluorometric method for the differentiation of algal populations in vivo and in situ , 2004, Photosynthesis Research.

[11]  U. Schreiber,et al.  Methodology and evaluation of a highly sensitive algae toxicity test based on multiwell chlorophyll fluorescence imaging. , 2007, Biosensors & bioelectronics.

[12]  J. Kromkamp,et al.  Estimating primary production rates from photosynthetic electron transport in estuarine microphytobenthos , 2000 .

[13]  R. Altenburger,et al.  Toxic effects of isoproturon on periphyton communities – a microcosm study , 2005 .

[14]  F. Colijn,et al.  Photosynthetic activity of natural microphytobenthos populations measured by fluorescence (PAM) and 14C-tracer methods: a comparison , 1998 .

[15]  E. Manders,et al.  Studying undisturbed autotrophic biofilms: still a technical challenge , 2004 .

[16]  S. Sabater,et al.  Monitoring the effect of chemicals on biological communities. The biofilm as an interface , 2007, Analytical and bioanalytical chemistry.

[17]  S. Wright,et al.  CHEMTAX - a program for estimating class abundances from chemical markers: application to HPLC measurements of phytoplankton , 1996 .

[18]  P. Juneau,et al.  Evidence for the Rapid Phytotoxicity and Environmental Stress Evaluation Using the PAM Fluorometric Method: Importance and Future Application , 1999 .

[19]  Daniel J. Repeta,et al.  Improved HPLC method for the analysis of chlorophylls and carotenoids from marine phytoplankton , 1991 .

[20]  U. Schreiber,et al.  Estimation of chlorophyll content and daily primary production of the major algal groups by means of multiwavelength-excitation PAM chlorophyll fluorometry: performance and methodological limits , 2005, Photosynthesis Research.

[21]  S. Jacquet,et al.  Application of a submersible spectrofluorometer for rapid monitoring of freshwater cyanobacterial blooms: a case study , 2002 .

[22]  H. Blanck,et al.  Long-term toxicity of zinc to bacteria and algae in periphyton communities from the river Göta Älv, based on a microcosm study , 2000 .

[23]  U. Schreiber,et al.  Computer-Controlled Phytoplankton Analyzer Based on a 4-Wavelengths Pam Chlorophyll Fluorometer , 1995 .

[24]  H. Blanck,et al.  Effects of sulfonylurea herbicides on non-target aquatic micro-organisms: Growth inhibition of micro-algae and short-term inhibition of adenine and thymidine incorporation in periphyton communities , 1999 .

[25]  P. Woitke,et al.  HPLC determination of lipophilic photosynthetic pigments in algal cultures and lake water samples using a non-endcapped C18-RP-column , 1994 .

[26]  R. Conrad,et al.  Changes in yield ofin-vivo fluorescence of chlorophyll a as a tool for selective herbicide monitoring , 1993, Journal of Applied Phycology.

[27]  J. Briantais,et al.  The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence , 1989 .

[28]  T. Backhaus,et al.  Predictability of the mixture toxicity of 12 similarly acting congeneric inhibitors of photosystem II in marine periphyton and epipsammon communities. , 2004, Aquatic toxicology.

[29]  Rolf Altenburger,et al.  Predicting and observing responses of algal communities to photosystem ii‐herbicide exposure using pollution‐induced community tolerance and species‐sensitivity distributions , 2005, Environmental toxicology and chemistry.

[30]  M. Kühl,et al.  A laboratory study on O 2 dynamics and photosynthesis in ice algal communities: quantification by microsensors, O 2 exchange rates, 14 C incubations and a PAM fluorometer , 2002 .

[31]  W. Renner,et al.  A quantitative method based on HPLC-aided pigment analysis to monitor structure and dynamics of the phytoplankton assemblage. A study from Lake Meerfelder Maar (Eifel, Germany) , 1991 .

[32]  Sergi Sabater,et al.  Contrasting effects of organic and inorganic toxicants on freshwater periphyton. , 2003, Aquatic toxicology.