(AMBI), to identify spatial and temporal impact gradients on benthic
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(AMBI), to identify spatial and temporal impact gradients on benthic
ICES CM 2003/Session J-01 THE USE OF A BIOTIC INDEX (AMBI), TO IDENTIFY SPATIAL AND TEMPORAL IMPACT GRADIENTS ON BENTHIC COMMUNITIES IN AN ESTUARINE AREA Iñigo Muxika, Á. Borja and J. Franco AZTI Foundation Department of Oceanography and Marine Environment Herrera Kaia, Portualdea, z/g 20110 – Pasaia (Spain) Tel: +34-943-004800; fax: +34-943-004801 e-mail: [email protected] Abstract Recently, several classification tools for the establishment of the quality of the marine environment have been developed in Europe. Benthic macroinvertebrates are the most traditionally used biological indicators of marine ecosystem health. AZTI has developed a tool (AMBI: www.azti.es), which provides assistance in determining the impacts and quality status within soft-bottom marine benthic communities; it is presently being used broadly along European coasts. In this communication, this tool is applied to the determination of spatial (at 8 sampling stations) and temporal (an 8 year data series) gradients within an estuarine system, together with its adjacent coastal area. This analysis was undertaken in order to determine both the impacts and improvement of the system quality. This tool has demonstrated its usefulness in detecting punctual impacts, being less influenced by the natural variability of the ecosystem. Keywords: biotic coefficient, impact evaluation, soft-bottom benthos, spatial gradient, temporal gradient Introduction Recently, several classification tools for the establishment of the quality of the marine environment have been developed in Europe, based upon different biotic compartments, as outlined below: Phytoplankton ✓ IFREMER is developing a tool, based on phytoplankton in France. Angiosperms and rocky shore communities: ✓ Swedish Classification Tool for Angiosperms and Rocky Shore Communities, developed bay the Swedish Environmental Protection Agency (2000). ✓ Ecological Evaluation Index: developed in Greece by Orfanidis et al. (2001), based upon seaweed and seagrasses. Soft-bottom macrozoobenthos ✓ Norvegian Classification Tool: developed by Molvaer et al. (1997), integrating chemical elements and benthic invertebrates. ✓ AMBI: developed by Borja et al. (2000), for use in European estuarine and coastal environments. ✓ Bentix: designed by Simboura and Zenetos (2002), for use in Mediterranean environments. Fish ✓ Biological Health Index (BHI): developed in South Africa by Cooper et al. (1994), it is currently being tested in the UK. ✓ Estuarine Fish Index (EFI): consists of seven metrics related to different functional aspects of the estuarine fish assemblages in order to integrate the quality of the ecosystem. It has been applied in the Scheldt estuary (Goethals et al., 2002; Adriaenssens et al., 2002a; Adriaenssens et al., 2002b). The AMBI (AZTI’s Marine Biotic Index) was developed to determine the impacts and the quality status in soft-bottom marine benthic communities. Subsequently, it has been applied under different impact sources, demonstrating its usefulness in detecting specific localized impacts as well as “diffuse pollution” (Borja et al., 2003a). Nowadays, it is being used broadly along European coasts. The principal advantage of this tool is that it is less influenced by cyclical natural variability of the ecosystem, that by changes in impact sources. The aim of this communication is to apply AMBI to an estuarine system (Plentzia, Spain; Figure 1) and its adjacent coastal area, to determine the spatial gradient induced by the pollution sources: (a) riverine imputs; (b) an aquaculture enterprise; (c) several outfalls, discharging into the estuary until 1998; (d) and a submarine outfall (see Figure 2) in the zone (Borja et al., 2003b). Likewise, the temporal evolution in the quality status, due to the changes in those pollution sources. Tallinn Plentzia Figure 1: Location of Plentzia (Spain) and Tallinn (Estonia). Material and Methods Station 1 was sampled from 1996 to 2002, Station 2 was sampled from 1995 to 2002 and three stations (3, 4 and 6) were sampled from 1997 to 2002, to establish the temporal evolution. Station 1 is littoral; the other four are estuarine stations (Figure 2). Each of the stations was sampled once a year, in autumn/winter. 11 2 1 10 9 8 Plentzia d 2 c 3 4 7 5 6 b a Figure 2: Location of the sampling stations (1 to 11). The stations sampled from 1995 to 2002 are shown in red; the stations sampled from 1997 to 2002 are shown in black. All the stations have been used to establish the spatial gradient. The main pollution sources (a to d) are shown by arrows (for explanation, see text). Eleven locations were sampled in autumn/winter 2002/2003, to establish the spatial gradient: Station 1 is in the littoral zone; Stations 2, 3, 4, 5, 6 and 7 are estuarine; and Stations 8, 9, 10 and 11 are located inside Plentzia harbour (Figure 2). For the calculation and interpretation of AMBI, see Borja et al. (2000, 2003a). The representation of the values, in the various plots, was made by means of Surfer 8. The load pollution index (LPI) was calculated on the basis of data abstracted from Borja et al. (2003b) and Franco et al. (2002), following the methodology proposed by Tomlinson et al. (1980). Heavy metals used to calculate LPI were: As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn. Background levels were those proposed by Borja et al. (1997). Results Determination of temporal gradients The temporal evolution for each of the stations is shown in Figure 3. Station 1 Station 2 STATION 1 STATION 2 e d c 6 5 4 3 b a 2 1 0 1996 1997 1998 1999 2000 2001 7 Biotic Coefficient Biotic Coefficient 7 e d c 6 5 4 3 b a 2 1 0 2002 1995 1996 1997 1998 1999 2000 2001 2002 Sampling Year Sampling Year Station 3 Station 4 STATION 3 STATION 4 7 e d c 6 5 4 3 Biotic Coefficient Biotic Coefficient 7 b a 2 1 0 1997 1998 1999 2000 2001 e d c 6 5 4 3 b a 2 1 0 2002 1997 1998 1999 Sampling Year 2000 2001 2002 Sampling Year Station 6 STATION 5 Biotic Coefficient 7 e d c 6 5 4 3 b 2 1 a 0 1997 1998 1999 2000 2001 2002 Sampling Year Figure 3: Temporal evolution of AMBI (the Biotic Coefficient) for each station, with the standard error shown as vertical error bars: a = unpolluted; b = slightly polluted; c = meanly polluted; d = heavily polluted; e = extremely polluted (Borja et al., 2000). Station 1 was slightly polluted in 1997, 1999, 2000 and 2002, and unpolluted in 1996 and 1998; nevertheless, it was with very similar values and restricted standard errors. Station 2 improved from 1995, when it was meanly polluted, to 1998 (slightly polluted over the three years). In 1999, this location was classified as heavily polluted; however, it improved to unpolluted in 2000. Subsequently, the AMBI has varied, but the station has been classified as slightly polluted in 2001, as well as in 2002. Station 3 has been classified as slightly polluted on all of the sampling occasions, except in 2000 and 2001, when it was meanly polluted. However, the derived AMBI values have been very similar throughout the time series. Station 4 was classified as slightly polluted, from 1997 to 1999. Subsequently, it worsened and has been classified as meanly polluted in 2000 and 2002. In 2001, it improved a little and was classified again as slightly polluted, but the AMBI value was still higher than in the first three years of the time series. Station 6 varied less throughout the time series; it has been classified throughout as meanly polluted. Determination of the spatial gradient The spatial gradient for each of the stations is shown in Figures 4 and 5. Figure 4: Spatial gradient of the AMBI values, in 2002. Note: for locations of the sampling stations, see Figure 2. The sampling stations can be divided into 3 groups, in terms of their classification. 1. Stations located adjacent to the mouth of an estuary (Stations 1 and 2): slightly polluted, with AMBI values ofaround 1.5. 2. “Estuarine” stations (3, 4, 5, 6 and 7): slightly polluted, but with AMBI values of around 3.0, except for Station 4 which is meanly polluted but with a high standard error (1.333). 3. Stations located in the harbour (8, 9, 10 and 11): meanly (the station located at the mouth of the harbour) or heavily polluted. 7 e d Biotic Coefficient 6 5 c 4 3 b 2 1 a 0 1 2 3 4 5 6 7 8 9 10 11 Station Figure 5: Spatial gradient of the AMBI values (Biotic Coefficient) in 2002. a = unpolluted; b = slightly polluted; c = meanly polluted; d = heavily polluted; e = extremely polluted. Discussion Temporal evolution There are no important pollution sources within the estuary (Borja et al., 2003b). The most important pollutants are transported by the river, from metallurgical and chemical industries: the main source of organic matter are farms. Hence, it is not a particularly stressed estuary. There are some sewerage works present and two water-treatment plants have been constructed in 1998. However, there is no particular trend within the series. This particular pattern could be explained in terms of the fact that the original situation was not particularly bad, in terms of pollutant levels: almost all of the stations were only slightly polluted. There is also a small outfall located near Station 1 (see Figure 2), but it does not seem to affect very much to the benthic community. The most important changes in the AMBI can be explained in terms of inputs under specific conditions, or through accidental waste disposal, through outfalls that are not used normally, but are used in specific situations (as floods). Spatial gradient The spatial gradient is as expected. The inner stations are more stressed, in response to changes in salinity pollutant inputs carried by the river. All of the stations in the estuary are classified as slightly polluted, except Station 4 which is meanly polluted (situated near the outfall of an aquaculture enterprise, see Figure 2). However, the outer stations (1 and 2) are located adjacent to the no pollution limit (AMBI = 1.2); likewise, the inner stations (3, 5, 6 and 7) are located nearer to the mean pollution limit (AMBI = 3.3). Inside the harbour, all of the stations are heavily polluted due to the restricted exchange of waters. This restriction implies: (i) slow water renewal; (ii) important pollutant retention; and (iii) increased levels of organic matter. The spatial gradient can be explained in terms of water renewal: (i) Station 8, in the mouth, is meanly polluted and the standard error is large (0.661), indicating a changing environment as the water enters and leaves, with the tidal movement carrying sediments; (ii) Station 9, the inner location, which presents less water renewal, (as such, it could be expected to be the most stressed station); (iii) Station 10, similar to the previous station, but the AMBI value is lower, as this station is nearer to the mouth of the harbour; (iv) Station 11 is very near to the mouth, presenting a lower value of AMBI and a higher standard error (0.386), indicating a changing environment (but not as important as at Station 8). General Discussion The contamination classification obtained using AMBI is listed in Table 3, with the classification obtained using the LPI (Borja et al. 2003b). The classification obtained by both methods appears consistent: the results are the same or very similar, except for Station 1 in 2001, Station 2 in 1995 and 1999, Station 4 in 2002, Stations 9 and 10 in 2002. These inconsistencies may be related to the greater or less bioavailability of metals, within the sediments. Table 3: AMBI classification, LPI classification and classification by toxicity criteria, for each station during each of the years. Key: UP=unpolluted; SP=slightly polluted; MP=meanly polluted; HP=heavily polluted. 1995 1996 1997 1998 1999 2000 2001 2002 AMBI LPI AMBI LPI AMBI LPI AMBI LPI AMBI LPI AMBI LPI AMBI LPI AMBI LPI St. 1 UP SP SP SP UP SP SP SP SP SP UP MP SP SP St. 2 MP UP SP UP SP SP SP UP HP UP UP SP SP SP SP St. 3 SP SP SP SP SP SP MP SP MP SP SP SP St. 4 SP SP SP SP SP SP MP SP SP MP MP UP St. 5 SP SP St. 6 MP SP MP SP MP SP MP SP MP SP SP UP St. 7 SP SP St. 8 MP St. 9 HP SP St. 10 HP SP St. 11 HP Conclusions a. AMBI permits the visualisation of spatial gradients, as well as temporal gradients. The results are consistent with those expected; They do not show any change, when there are no changes in the pollution sources. b. Nonetheless, the AMBI changes very rapidly when a new pollution source is introduced. However, when an input disappears, the AMBI shows a slow recovery; this reflects the slow recovery of the benthic community. c. AMBI is very easily understandable and a program is freely available in www.azti.es, which it can be calculated. Acknowledgements The study of the Plentzia estuary was supported by different contracts undertaken between the Departmento de Ordenación del Territorio, Vivienda y Medio Ambiente of the Basque Government and AZTI and between the Consorcio de Aguas Bilbao-Bizkaia and AZTI. The study of Plentzia harbour was supported by a contract between Dirección de Puertos of the Basque Government. One of the authors, I. Muxika was supported by a grant from the Technological Centres Foundation of the Basque Country. We wish to thank also Professor Michael Collins (School of Ocean and Earth Science, University of Southampton, UK) for kindly advising us on some details of this paper. References ADRIAENSSENS, V.; GOETHALS, P.L.M.; BREINE, J.J.; MAES, J.; SIMOENS, I.; ERCKEN, D.; BELPAIRE, C.; OLLEVIER, F.; & DE PAUW, N.; 2002a. Importance of references in the development of an estuarine fish index in Flanders (in Dutch). Landschap, 19: 59-62. ADRIAENSSENS, V. ; GOETHALS, P.L.M.; DE PAUW, N.; BREINE, J.J.; SIMOENS, I.; MAES, J.; ERCKEN, D.; BELPAIRE, C.; & OLLEVIER, F.; 2002b. Development of an estuarine fish index in Flanders (in Dutch). Water, June 2002: 1-13. BORJA, Á.; FRANCO, J.; & PÉREZ, V.; 2000. A Marine Biotic Index to Establish the Ecological Quality of Soft-Bottom Benthos within European Estuarine and Coastal Environments. Marine Pollution Bulletin, 40: 1100-1114. BORJA, Á.; FRANCO, J.; VALENCIA, V.; URIARTE, A.; Y CASTRO, R.; 1997. Red de vigilancia y control de las aguas litorales del País Vasco: otoño 1995-verano 1996. Informe Final. UTE AZTI-LABEIN, Departamento de Ordenación del Territorio, Vivienda y Medio Ambiente, Gobierno Vasco. 296 pp. + annexes. (Unpublished Report) BORJA, Á.; GARCÍA DE BIKUÑA, J.M.; BLANCO, A.; AIERBE, E.; BALD, J.; BELZUNCE, M.J.; FRAILE, H.; FRANCO, J.; GANDARIAS, O.; GOIKOETXEA, I.; LEONARDO, J.M.; LONBIDE, L.; MOSO, M.; MUXIKA, I.; PÉREZ, V.; SANTORO, F.; SOLAUN, O.; TELLO, E.M.; VALENCIA, V.; 2003b. Red de Vigilancia de las masas de agua superficial de la Comunidad Autónoma del País Vasco. Tomo 5: Unidad Hidrológica del Butroe. Departamento de Ordenación del Territorio y Medio Ambiente, Gobierno Vasco. 190 pp. BORJA, Á.; MUXIKA, I.; FRANCO, J.; 2003a. The application of a Marine Biotic Index to different impact sources affecting soft-bottom benthic communities along European coasts. Marine Pollution Bulletin, 46: 835-845. COOPER, J.A.G.; RAMM, A.E.L.; & HARRISON, T.D.; 1994. The Estuarine Health Index: A new approach to scientific information transfer. Ocean & Coastal Management, 25: 103-141. FRANCO, J.; BORJA, Á.; CASTRO, R.; SOLAUN, O.; MUXIKA, I.; VILLATE, F.; 2003. Seguimiento ambiental de los estuarios del Nervión, Barbadún y Butrón durante 2002. Consorcio de Aguas Bilbao Bizkaia. (Unpublished Report) GOETHALS, P.L.M.; ADRIANSSENS, V.; BREINE, J.; SIMOENS, I.; VAN LIEFFERINGHE, C.; ERCKEN, D.; MAES, J.; VERHAEGEN, G.; OLLEVIER, F.; DE PAUW, N.; & BELPAIRE, C.; in press, 2002. Developing an index of biotic integrity to assess fish communities of the Scheldt estuary in Flanders (Belgium). Aquatic Ecology. TOMLINSON, D.L.; WILSON, J.G.; MARRIS, C.R.; AND JEFFREY, D.W.; 1980. Problems in the assessment of heavy metal levels in estuaries and the formation of pollution index. Helgolander Meeresuntersuchugen, 33: 566-575. MOLVAER, J.; KNUTZEN, J.; MAGNUSSON, J.; RYGG, B.; SKEY, J.M.; & SORENSEN, J.; 1997. Classification of environmental quality in fjords and coastal waters. A guide. Veiledning 97:03. Norwegian Pollution Control Authority, Oslo. 35 pp. [in Norwegian] ORFANIDIS, S.; PANAYOTIDIS, P.; AND STAMATIS, N.; 2001. Ecological evaluation of transitional and coastal waters: A marine benthic macrophytes-based model. Mediterranean Marine Science, 2: 45-65. SIMBOURA, N. AND ZENETOS, A.; in press, 2002. Benthic indicators to use in Ecological Quality Classification of Mediterranean soft bottom marine ecosysems, including a new Biotic Index. Mediterranean Marine Science, 3/2: 77-111. SWEDISH ENVIRONMENTAL PROTECTION AGENCY; 2000. Report 5052: Environmental Quality Criteria, Coasts and Seas. www.environ.es
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