Freshwater Algae: Identification and Use as Bioindicators

More documents

Recommendations

Info

128 3 ALGAE AS BIOINDICATORSTable 3.13 Calculation of the Diatom Index (I d ): River Semois (Round 1993)Diatom a j v j a j × v j s j a j × v j × .s j I dAchnanthes lanceolata 0.9% 1 0.9 3 2.7Gomphonema parvulum 0.5% 1 0.5 2 1.0Navicula accomoda 78.7% 3 235.1 1 235.1Nitzschia palea 19.7% 2 39.4 1 39.4Others 0.2%Total 275.9 278.2 278.2/275.9 = 1.0See text for symbols and I d calculation (equation 3.3).value of TDI ranged from 1 (very low nutrient concentrations)to 5 (very high nutrients).This index has now been modified (Kelly, 2002) toincrease the range from 0–100, where:TDI = (WMS × 25) − 25 (3.4)ISL Index (Index of saprobic load): Sladecek,1986 This index of soluble organic pollution(saprobity) is based on 323 diatom taxa, each with adesignated saprobic value. Values range from 4.5–0(polluted to non-polluted water).3.4.6 Practical applications of diatom indicesThe diversity of available and currently-used diatomindices presents a complex and confusing picture as towhich ones should be used to ensure comparabilityof studies and consistency of approach. A furtherpotential source of confusion is that some indices (e.g.TDI, see above) have been subsequently modifiedto give a wider range of values in relation to waterquality. The range of available diatom indices raisesa number of key practical issues, including: which index? ease of use comparability between diatom indices comparability between diatoms and other bioindicatororganisms differences between indices in response to changesin water quality adoption of a standard approach to use of diatomsas bioindicator organisms quality assurance: reliability of analyst assessment.Which index? Ease of useOne practical problem with the use of diatoms asbioindicators is the large number of taxa encounteredin environmental samples. This can be overcome intwo main ways. Use indices based on genera (e.g. GDI) rather thanspecies (e.g. SPI, TDI). Various researchers (e.g.Case study 3, below) have found no significant differencesbetween the two. Restrict identification to the most abundant species.Round (1993), for example, used about 20 keyspecies for monitoring rivers in the United Kingdom.Comparability between indicesRecent projects using diatoms as bioindicators havetended to use groups of indices, to eliminate
3.4 RIVERS 129any irregular conclusions that might have arisenfrom use of a single index. Different indices havebeen compared for assessment of water qualitywithin different river systems, where there is variationin trophic status (inorganic nutrients – particularlyphosphates and nitrates) and a range ofother factors such as salinity, organic pollution(related to biological oxygen demand – BOD)and industrial contamination (metal pollution andacidity).A summary of studies is shown in Table 3.14, withsome detailed examples below. In general, differentdiatom indices give broadly comparable results. Variousstudies (e.g. Case studies 3 and 4 below) do indicate,however, that the IPS index is particularly usefulfor monitoring general changes in water quality. Thisindex best reflects the combined effects of eutrophication,organic pollution and elevated salt concentrations,since it usually integrates all diatom speciesrecorded within the samples.Case study 3.2 Field studies using different diatom indices (Table 3.14)1. Greek rivers: variation in trophic status, organic and inorganic chemical pollutants. Iliopoulou-Georgudakiet al. (2003) used IPS, Descy 1979 and CEE indices as they were considered more representative of environmentalconditions. The indices gave exactly comparable results.2. Selected rivers in England and Scotland. Ranging from nutrient-poor upland streams to lowland rivers subjectto varied eutrophication and contamination with organic pollutants, pumped minewater, heavy metals andagricultural run-off.Kelly et al. (1995) assessed water quality using four indices based on diatom genera (GDI) and species (SPI,TDI-P and TDI-NP). The high correlation between indices across the different river sites suggested that anycould be used individually for routine monitoring and that diatom recognition to genus rather than specieslevel was adequate.3. Metal pollution in lowland river. DeJongeet al. (2008) assessed diatom populations in relation to metal(ZN) contamination and related physicochemical variables. The IPS index best reflected changes in waterquality (pH, conductivity, oxygen concentration, inorganic nutrients), and was the only diatom index thatindicated a significant difference between control and contaminated sites.4. Rivers of southern Poland: variation in trophic status and organic pollution. Kwandrans et al. (1998) usedthe suite of 8 diatom indices contained in the OMNIDIA database software to evaluate water quality in thisriver system. Except for Sladek’s index, indices typically showed significant correlations with each other andalso with parameters of water quality: organic load (BOD), oxygen concentration, conductivity, measuredion concentrations and trophic level (NH 4 -N, PO 4 -P). Two particular indices – IPS and GDI, gave the bestenvironmental resolution in terms of correlation with water quality variables (see Table 3.6) and showingclear differences between the separate river groups.Although the diatom indicator system emerged as a useful tool to evaluate general water quality, someindices were not able to differentiate between adverse effects of eutrophication (inorganic nutrients) andorganic material pollution. Abundance of key indicator species, however, such as Achnanthes minutissima(highly sensitive towards organic pollution) and Amphora pediculus (eutrophic species, sensitive to organicpollution) can be useful in evaluating the type of pollution involved.
Page 1 and 2: 3Algae as BioindicatorsBiological i
Page 3 and 4: 3.1 BIOINDICATORS AND WATER QUALITY
Page 5 and 6: Table 3.3 Lake Trophic Status: Phyt
Page 8 and 9: 106 3 ALGAE AS BIOINDICATORSDirecti
Page 11 and 12: 3.2 LAKES 109sites (Fig. 3.3 A, B,
Page 13 and 14: 3.2 LAKES 111Phytoplankton net prod
Page 15 and 16: 3.2 LAKES 113and hypertrophic (Pedi
Page 17 and 18: 3.2 LAKES 115Table 3.5 Organic Poll
Page 19 and 20: 3.2 LAKES 117Table 3.7 Bioindicator
Page 21 and 22: 3.3 WETLANDS 119therefore directly
Page 23 and 24: 3.4 RIVERS 1213.4 RiversUntil recen
Page 25 and 26: 3.4 RIVERS 123Gomphonema parvulum t
Page 27 and 28: 3.4 RIVERS 125Table 3.10 Benthic Di
Page 29: 3.4 RIVERS 127Palmer’s Index (Pal
Page 33 and 34: 3.4 RIVERS 131Case study 3.3Compari
Page 35 and 36: individual analysts can be measured
Page 37 and 38: 3.5 ESTUARIES 135potential role of

Freshwater Algae: Identification and Use as Bioindicators

Create successful ePaper yourself

Delete template?

Save as template?