Addressing the removal of rare species in multivariate bioassessments: The impact of methodological choices

Poos, Mark S.; Jackson, Donald A.

doi:10.1016/j.ecolind.2011.10.008

Cited by 136 publications

(77 citation statements)

References 37 publications

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“…Nevertheless, this debate is ongoing with researchers offering contrasting positions and findings (Cao and Williams, 1999;Marchant et al, 1999;Poos and Jackson, 2012). Very little is known about the effect of rare taxa for calculating single or multimetric macroinvertebrate-based indices or about the effect on ecological status assessments, especially in South Europe.…”

Section: Introductionmentioning

confidence: 99%

How do low-abundance taxa affect river biomonitoring? Exploring the response of different macroinvertebrate-based indices

2016

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The contribution of rare taxa to aquatic bioassessments remains a subject of debate, and generates contrasting positions among researchers. Very little is known about the effect of low-abundance taxa (LAT) for calculating both single and multimetric macroinvertebrate-based indices, as well as the ecological status classification. In this study, we aimed to: i) identify the aquatic macroinvertebrates that need special attention during index applications given their low abundance; ii) analyse the effect of excluding LAT on single (IBMWP and IASPT) and multimetric (STAR_ICMi) biological indices; and iii) investigate the influence of LAT on river ecological status assessments. To this end, two different river basins in SE Spain and N Italy with contrasting climatic conditions and river types were selected. Our results showed that almost all the taxa at the family level can act as low-abundance taxa. In particular, the LAT belonged mainly to Diptera, Trichoptera, Coleoptera, Gastropoda and Hemiptera. The IndVal analysis stressed Tabanidae, Cordulegasteridae and Hydroptilidae as the most characteristic low-abundance families in the Spanish data set, while Dryopidae and Athericidae were identified mostly in N Italy. Excluding LAT affected the studied index values and the resulting bioassessment classification, except for the IASPT index. Loss of the entire LAT pool reduced the ecological status for 78% of the samples for the IBMWP index. Changing took place in 41% of the samples when considering the STAR_ICM index. Relevant changes were detected even when considering loss of 50% of the LAT, especially with the IBMWP index. Similar values and patterns were obtained in each considered quality class and river type. Our results provide useful information about controversial taxa and stress the significance of LAT in river biomonitoring. Excluding LAT is discouraged, although different responses according to the considered index were detected. The IBMWP index always obtained lower values (coupled mainly with an underestimation of ecological classes), while STAR_ICMi and, especially the IASPT index, were less affected by excluding LAT. Paying special attention to all the protocol application stages is recommended, with emphasis placed when using the IBMWP index.

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Section: Introductionmentioning

confidence: 99%

How do low-abundance taxa affect river biomonitoring? Exploring the response of different macroinvertebrate-based indices

2016

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“…Response and explanatory matrices contained all sites. The response matrices of families and morphospecies included taxa that we sampled at three or more sites (62 families and 120 morphospecies; [62], [63] but see [66]). These matrices were relativized by maximum abundance for each family or morphospecies.…”

Section: Methodsmentioning

confidence: 99%

Effects of a Long-Term Disturbance on Arthropods and Vegetation in Subalpine Wetlands: Manifestations of Pack Stock Grazing in Early versus Mid-Season

2013

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Conclusions regarding disturbance effects in high elevation or high latitude ecosystems based solely on infrequent, long-term sampling may be misleading, because the long winters may erase severe, short-term impacts at the height of the abbreviated growing season. We separated a) long-term effects of pack stock grazing, manifested in early season prior to stock arrival, from b) additional pack stock grazing effects that might become apparent during annual stock grazing, by use of paired grazed and control wet meadows that we sampled at the beginning and end of subalpine growing seasons. Control meadows had been closed to grazing for at least two decades, and meadow pairs were distributed across Sequoia National Park, California, USA. The study was thus effectively a landscape-scale, long-term manipulation of wetland grazing. We sampled arthropods at these remote sites and collected data on associated vegetation structure. Litter cover and depth, percent bare ground, and soil strength had negative responses to grazing. In contrast, fauna showed little response to grazing, and there were overall negative effects for only three arthropod families. Mid-season and long-term results were generally congruent, and the only indications of lower faunal diversity on mid-season grazed wetlands were trends of lower abundance across morphospecies and lower diversity for canopy fauna across assemblage metrics. Treatment x Season interactions almost absent. Thus impacts on vegetation structure only minimally cascaded into the arthropod assemblage and were not greatly intensified during the annual growing season. Differences between years, which were likely a response to divergent snowfall patterns, were more important than differences between early and mid-season. Reliance on either vegetation or faunal metrics exclusively would have yielded different conclusions; using both flora and fauna served to provide a more integrative view of ecosystem response.

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“…A multiresponse permutation procedure was used to test for significant differences in the fish assemblages between infected and uninfected streams. We retained rare species (<5% occurrence) in our multivariate analyses to improve our ability to detect subtle ecological gradients (Cao et al 1998;Poos and Jackson 2012). However, as a precaution, analyses were conducted both with and without rare species, which indicated that inclusion of rare species did not change the interpretation of results.…”

Section: Environmental and Fish Assemblage Analysesmentioning

confidence: 99%

Weak effects of a microsporidian parasite on mottled sculpin in Michigan streams

HomolaJared

IIICarl

KohlerSteven

et al. 2014

Can. J. Fish. Aquat. Sci.

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Despite the widespread occurrence of microsporidian parasites in vertebrates and many invertebrates, research regarding their effects on wild populations remains uncommon. We used several metrics of individual growth, condition, and population characteristics to evaluate the effects of a microsporidian infection (Glugea) on six infected populations of mottled sculpin (Cottus bairdii) compared with 10 nearby uninfected populations. Infected individuals (n = 129) were significantly heavier in each age class when compared with uninfected fish (n = 331), yet other measures of growth and condition indicated little influence of the parasite. No significant parasite-associated effects were found when comparing mortality rates, mean age, sex ratios, and history of population genetic bottleneck between infected and uninfected populations. Additionally, we did not detect significant differences in environmental variables or fish assemblages between streams with and without the parasite. Given the disfiguring nature of infection and the strong effects of microsporidian parasites on other hosts, the lack of significant effects caused by parasitism was unexpected and is likely attributed to strong host density-dependent population dynamics or relatively low host infection intensities.Résumé : Bien que les microsporidies parasites soient répandues chez les vertébrés et de nombreux invertébrés, les travaux sur leurs effets sur les populations sauvages demeurent assez rares. Nous avons utilisé plusieurs mesures de la croissance et de l'état individuels et des caractéristiques de la population pour évaluer les effets d'une infection à microsporidie (Glugea) sur six populations infectées de chabot tacheté (Cottus bairdii) par rapport à 10 populations non infectées voisines. Si les individus infectés (n = 129) étaient significativement plus lourds dans chaque catégorie d'âges comparativement aux poissons non infectés (n = 331), d'autres mesures de la croissance et de l'état indiquaient peu d'influence du parasite. Aucun effet significatif associé au parasite n'a été noté sur le plan des taux de mortalité, de l'âge moyen, du rapport des sexes et de l'historique de goulots d'étranglement génétiques entre les populations infectées et non infectées. En outre, nous n'avons décelé aucune différence significative des variables du milieu ou des assemblages de poissons entre les cours d'eau avec et sans parasites. Étant donné l'effet défigurant de l'infection et les effets importants de microsporidies parasites sur d'autres hôtes, l'absence d'effets significatifs causés par le parasitisme était inattendue et serait vraisemblablement attribuable à une dynamique de la population fortement dépendante de la densité des hôtes ou des intensités d'infection relativement faibles des hôtes. [Traduit par la Rédaction]

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Addressing the removal of rare species in multivariate bioassessments: The impact of methodological choices

Cited by 136 publications

References 37 publications

How do low-abundance taxa affect river biomonitoring? Exploring the response of different macroinvertebrate-based indices

How do low-abundance taxa affect river biomonitoring? Exploring the response of different macroinvertebrate-based indices

Effects of a Long-Term Disturbance on Arthropods and Vegetation in Subalpine Wetlands: Manifestations of Pack Stock Grazing in Early versus Mid-Season

Weak effects of a microsporidian parasite on mottled sculpin in Michigan streams

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