Shannon Equitability Index Research Articles

Assessment of butterflies diversity, and distribution in Ghamot National Park, Western Himalaya, Neelum valley, Pakistan

Biodiversity measures, species richness and species evenness. Species richness means the number of species present in designated area whereas evenness stands for relative abundance of each species. Butterflies are very important economically. They feed on nectar from flowers by using proboscis. Butterflies act as excellent bio indicator of health of natural ecosystem. The fauna in the study area lacks comprehensive documentation hence there has been no previous assessment of butterfly biodiversity. The study was conducted to estimate species richness, species evenness, and species diversity through a comparative analysis across different habitat types. The Pollard walk method, specifically a butterfly transects count and visual Surveys was used to collect specimen in Ghamot National Park divided into 8 localities. A total of 37 transects covering an area of 12.55 km 2 were established and observed on a monthly basis from June 2020 to July 2021. A collection of 211 specimens was obtained using various standard methods. In order to assess the butterfly population, diversity metrics including the Shannon-Wiener index, Shannon equitability index, Margalef index, and Simpson index were employed. The study documented a total of 539 individuals representing 16 species and 3 butterfly families in 8 different localities with varying habitats. The forest-dominated zones exhibited the highest abundance (n=266; 49.53%) and species richness (n=15; 93.75). Additionally, the forest zone demonstrated the maximum values for the Shannon-Wiener diversity index (3.77) and Simpson index (0.92), while the riparian zone displayed the lowest diversity (3.02) and Simpson index (0.89) among the four selected localities. Therefore, it is recommended that regular monitoring of the study area be undertaken to observe potential fluctuations in butterfly diversity. Continuous surveillance and comparative analysis of data from year to year are essential for identifying any shifts in butterfly populations

Analysis of Avian Diversity at Chintamoni Kar Bird Sanctuary: An Urban Forest Perspective

Chintamoni Kar Bird Sanctuary (CKBS) is an urban forest located on the southern fringes of Kolkata. The objective of our study was to document and analyze the diversity of the avian population in CKBS. The line transect method was used and avian diversity, species richness and evenness were analyzed using Shannon Diversity Index, Shannon Equitability Index, relative diversity and relative abundance. Our study recorded 37 bird species belonging to 9 orders and 23 families with most species being recorded from Order Passeriformes followed by Piciformes and Ciconiiformes. The species were well distributed across a number of avian families. Birds rare in metropolises like the Oriental white eye (Zosterops palpebrosus) were also recorded here. Analysis of relative abundances showed that many species comparatively rare in cities like the common tailor bird (Orthotomus sutorius) and white throated fantail (Rhipidura albicollis) showed an abundance similar to more commonly seen species. Values of 2.844 and 0.788 were obtained for Shannon Diversity Index and Shannon Equitability Index indicating high species diversity and evenness. However, high species diversity is not due to assemblage of migratory birds in winter. Species diversity and evenness are highest during the summer months (Shannon Diversity Index = 2.862; Shannon Equitability Index = 0.812) which could be due to dense forest cover, a large number of fruit bearing trees and many water bodies in the sanctuary which provide a favourable habitat for birds in hot weather. Our study indicates that a number of birds appear to be thriving as a stable avian community at CKBS and this urban forest acts as a haven for bird species otherwise rare in Kolkata, further emphasizing the need for taking necessary conservation measures for protection for this urban forest under the strained environmental conditions prevalent in urban metropolises.

Assessment of Bees’ Diversity within Ngel-Nyaki Forest Reserve at Taraba State, Nigeria

A field survey was conducted in Ngel-Nyaki Forest Reserve to assess the diversity of bees within the Reserve. Two methods of sampling techniques were used to sample bee species, opportunistic sampling and systematic sweep netting. Opportunistic sampling method was applied by sweep netting bees along 100 m plot where flowering plants were blooming. Collection was conducted by a single collector using an active search by walking randomly around the plot observing flowering plants and searching for bees foraging on the flowers then a sweep net was used for capturing bees. Sweep netting was conducted, line transect established within the plots for two hours, from 6:00am to 11:00am spending 20 minutes in each plot considering when the weather is conducive for bees’ activity. This was done using entomological sweep net. Bees captured were killed in a killing bottle containing 70% ethanol. Specimens were pinned on a board and unique codes were assigned to each species before identification. Bees were identified to species level by using published systematic keys, Bees field guide and use of online materials. All data were computed using Microsoft® Excel® 2016 and percentage abundance composition of bees were calculated.575 bees spreading across 3 families and 12 species were sampled. The most abundant species was the honey bee (Apismellifera) (245; 42.53%),followed by memic bee (Megachile sp.)(89;15.45%),and the least was leafcutter bee(Osmiasp.) (2;0.35%). In terms of diversity by species, Shannon Diversity Index (H) and Shannon Equitability Index (EH) were 1.694893 and 0.736083respectively while diversity by plots using Shannon Diversity Index (H) and Shannon Equitability Index (EH) were 1.750688 and 0.977078 respectively. This study therefore, brings to the fore the diversity of bees within Ngel-Nyaki Forest Reserve and underline the need for sustainable actions to be taken to conserve beneficial rare species while managing the abundant ones.

Diversity, Composition and Abundance of Avian Species of Oxbow Lake and Surrounding Area in Purbasthali, West Bengal, India

Purbasthali oxbow lake is an important habitat for thousands of migratory and resident avian species. This study aimed to determine the current status of avifaunal diversity of Purbasthali oxbow lake and its surrounding area. During this study, diversity, composition and abundance, feeding guilds and the relationship between their habitat preferences and the numbers of individuals were determined. Direct observation, line transects and point count methods were applied for bird surveys for three consecutive years from 2019 to 2022. A total of 145 species of birds were documented, belonging to 19 orders and 49 families. Among the total species, 57 are migratory in nature and 47 are showing declining global trend. Quantitative diversity estimation were performed during the study are the Shannon-Weiner index, Simpson's Diversity Index, Shannon equitability index and relative diversity. Density and diversity of avian species was highest during post-monsoon and lowest in pre monsoon. This indicates the winter assemblages of many migratory birds choose this lake as their feeding and resting grounds.

Diversity of duckweed (<i>Lemnaceae</i>) associated yeasts and their plant growth promoting characteristics

<abstract> <p>The diversity of duckweed (<italic>Lemnaceae</italic>) associated yeasts was studied using a culture-dependent method. A total of 252 yeast strains were isolated from 53 duckweed samples out of the 72 samples collected from 16 provinces in Thailand. Yeast identification was conducted based on the D1/D2 region of the large subunit (LSU) rRNA gene sequence analysis. It revealed that 55.2% and 44.8% yeast species were Ascomycota and Basidiomycota duckweed associated yeasts, respectively. Among all, <italic>Papiliotrema laurentii</italic>, a basidiomycetous yeast, was found as the most prevalent species showing a relative of frequency and frequency of occurrence of 21.8% and 25%, respectively. In this study, high diversity index values were shown, indicated by the Shannon-Wiener index (<italic>H′</italic>), Shannon equitability index (<italic>E<sub>H</sub></italic>) and Simpson diversity index (<italic>1-D</italic>) values of 3.48, 0.86 and 0.96, respectively. The present results revealed that the yeast community on duckweed had increased species diversity, with evenness among species. Principal coordinate analysis (PCoA) revealed no marked differences in yeast communities among duckweed genera. The species accumulation curve showed that the observed species richness was lower than expected. Investigation of the plant growth promoting traits of the isolated yeast on duckweed revealed that 178 yeast strains produced indole-3-acetic acid (IAA) at levels ranging from 0.08–688.93 mg/L. Moreover, siderophore production and phosphate solubilization were also studied. One hundred and seventy-three yeast strains produced siderophores and exhibited siderophores that showed 0.94–2.55 activity units (AU). One hundred six yeast strains showed phosphate solubilization activity, expressed as solubilization efficiency (SE) units, in the range of 0.32–2.13 SE. This work indicates that duckweed associated yeast is a potential microbial resource that can be used for plant growth promotion.</p> </abstract>

BUTTERFLIES AND MOTHS (ORDER: LEPIDOPTERA) IN PULAU TINGGI, JOHOR, MALAYSIA

Pulau Tinggi is a relatively unexploited island located in the middle arc of the Seribuat Archipelago in Johor, Malaysia. This study is the first to record species of moths and butterflies (Order: Lepidoptera) on the island. Specimens were collected between April and August 2019 through passive sampling methods such as light and baited traps. Active sampling was also done opportunistically using aerial nets. The results showed that Lepidopteran on the island has a high species richness and abundance. A total of 624 individuals from 121 species of Lepidoptera were identified. Out of that, 105 species were butterflies and 16 were moths. The Shannon-Weiner Index (H’) value for both butterfly and moth was 4.29. Evenness, measured using Shannon Equitability Index (EH) was valued at 0.89. Gauging the diversity of fauna in a relatively unexplored island such as Pulau Tinggi is important for properly managing its natural resources. In the near future, activities such as entomotourism may be done in the area to support the local economic ecosystem while ensuring the conservation of the island’s biodiversity.

Multiple indicators of household dietary diversity in rural China: Effects of income and dietary knowledge

Objective:The aim of this study was to examine the association among family income, dietary knowledge, their interaction, and the multiple household dietary diversity indices (HDDIs), including dietary diversity score (DDS), entropy index (EI), Shannon equitability index (SEI), Herfindahl index (HI), and Simpson index (SI).Methods: Based on 24-h dietary recall data collected from 1076 rural households in three provinces of Central China, we calculated HDDIs and compared them according to different levels of income and dietary knowledge. A set of multivariate linear regression were further established and estimated to examine the association among family income, dietary knowledge, and household dietary diversity.Results: Although the calculation formulas are different, the distributions of the five diversity indices, namely, DDS, EI, SEI, HI, and SI are similar. Family income and dietary knowledge were significantly and positively correlated with various HDDIs (P < 0.01) in addition to HI. Specifically, with a 1-unit (10 000 yuan [US $1545]) income increase, the DDIs respectively changed by 1.70% (DDS), 1.23% (EI), 0.92% (SEI), –0.62% (HI, reverse), and 0.45% (SI). With a 1-point dietary knowledge score increase, the DDIs changed by 0.91% (DDS), 1.33% (EI), 1.29% (SEI), –1.19% (HI, reverse), and 0.81% (SI). The interaction effect of income and dietary knowledge on HDDIs were significantly and negatively correlated with various HDDIs (P < 0.05) in addition to HI.Conclusions: The present findings indicated that with an increase in income and dietary knowledge, rural residents in China would consume more diversified foods. There was a substitution effect of family income and dietary knowledge on HDDIs; that is, with an increase in family income, the effect of dietary knowledge on HDDIs would decrease. The findings of this study contributed to a better understanding of issues related to the dietary diversity of rural residents in China in the context of rising income and residents’ increasing dietary knowledge.

Optimizing crop mix with respect to economic and environmental constraints: An integrated MCDM approach

This study develops an integrated framework for assessment of cropping sustainability at the aggregate (country) level. Such sustainability criteria as total water footprint, Shannon equitability index, total output, and downside coefficient of yield variation are used to rank the crop mixes, corresponding to different assumptions. Mathematical programming model is applied to generate the crop mixes. Then, the three MCDM techniques (SAW, TOPSIS and EDАS) are applied for the ranking. Empirical analysis embarks on the case of Lithuania, which is a new EU member state. Sensitivity analysis is carried out by establishing the three weighting schemes (balanced, environment- and economy-oriented). The results suggest that scenario minimizing labour use render the most sustainable crop-mix. Correlation among the ranks of the scenarios suggests that environmental and economic approaches are conflicting between themselves, yet there is no such a serious contradiction among the latter two approaches and the balanced approach.

Diversidad y mecanismos de dispersión de árboles de la Isla Gorgona y de los bosques húmedos tropicales del Pacífico colombo-ecuatoriano

En este trabajo se hizo una comparación entre la flora de la isla Gorgona (Colombia) y la de los bosques del Chocó biogeográfico (Colombia y Ecuador). Para esta comparación se utilizaron curvas de acumulación de especies e índices de riqueza y diversidad. tanto publicadas por diferentes autores o generadas a partir de los inventarios florísticos OIiginales. La riqueza del bosque de la isla Gorgona calculada ápmti{de curvas especie-área y del índice de diversidad de Shannon fue inferior a la de varios bosques colombianos y ecuatorianos en las tierras bajas del continente. Adicionalmente, el índice de equitabilidad dé Shannón en cinco bosqués, del' Pacífico colombo-ecuatoriano fue mayor que el de la isla Gorgona. lo cual sugiere que en los bosques continentales las especies están representadas por un número similar de individiíbs. La ornitocoria fue el mecanismo de dispersión más importante en la isla Gorgona (49.7%), en forma similar a lo encontrado para las islas Galápagos en Ecuador (60 %) Y para la isla biogeográfica del bosque nublado de la Serranía de la Macuira, Guajira, en el norte de Colombia (51 %). En contraste, la dispersión por mamíferos fue el mecanismo más importante para las especies de árboles del bosque continental de Cabo Corrientes, de BajoCalima (Colombia) y los Tuxtlas (México). A pesar de que los bosques de la Isla Gorgona, no son especialmente ricos en especies, cumplen una importante función protectora de los ecosistemas de coral que rodean la isla. Una reducción de la cobertura boscosa tendría como consecuencia un aumento de las tasa de erosión y avalanchas que afectarían gravemente los ecosistemas marinos, en particular los arrecifes de coral.

Community diversity and total abundance: Quantitative predictions from competition niche theory

Lotka–Volterra niche competition theory (LVNCT) is based on Lotka–Volterra competition equations with competition coefficients between pairs of species determined by the intensity of their niche overlap though the MacArthur–Levins niche overlap formula. Here I study analytically and numerically the predictions of LVNCT concerning total abundance and biodiversity, measured by the Shannon equitability index. Firstly, a set of simplifying assumptions that render the LVNCT amenable of analytical treatment are considered. In particular I derive an approximated formula for the total abundance, as the inverse of the mean value of the interspecific competition coefficients, which works pretty well both for the transient and steady regime and for a wide range of the typical niche width σ. Secondly, I analyze, by means of simulations, the effect of relaxing the above simplifying assumptions when considering more realistic conditions. It turns out that the approximated formula for the total abundance is quite robust and its potential implications for management are discussed. I also analyze the predicted relationship between community productivity and diversity.

Gut microbial status induced by antibiotic growth promoter alters the prebiotic effects of dietary DVAQUA® on Aeromonas hydrophila-infected tilapia: Production, intestinal bacterial community and non-specific immunity

The purpose of the present study was to investigate whether dietary antibiotic-induced changes in the fish intestinal microbiota altered host physiological responses to the infection with Aeromonas hydrophila in hybrid tilapia (Oreochromis niloticus ♀×O. aureus ♂). After an 8-week induction period with an antibiotic-supplemented or antibiotic-non-supplemented diet, 160 hybrid tilapias in 16 tanks were each injected with phosphate buffered saline (PBS) or A. hydrophila at a dose of one-half of the LD50. Then, all of the diets were changed to a prebiotic-supplemented one for the sequential 8-week response period. Parameters including production, gut microbial diversity and count, and non-specific immunity were determined at the end of the response period. Our results showed that A. hydrophila infection had no effects on the growth and diet conversion of tilapia, but it caused the decrease of the gut bacterial count, the number of visual bands, and the Shannon diversity and equitability indexes of gut bacteria in antibiotic-non-supplemented fish based on PCR-DGGE fingerprints. Infection with A. hydrophila reduced the gut bacterial evenness (lower Shannon equitability index), and slightly improved the gut bacterial richness (more visual bands) in antibiotic-supplemented tilapia. In addition, A. hydrophila infection affected non-specific immunity such as serum lysozyme activity and serum alternative complement pathway (C3 and C4) activities regardless of hybrid tilapia fed antibiotic-supplemented diets. These changes varied based on the intestinal microbial status of the fish before infection with A. hydrophila.

Analysis of bacterial diversity in the intestine of grass carp (Ctenopharyngodon idellus) based on 16S rDNA gene sequences

In the current study, we assessed bacterial diversity in the gut content of pond-reared grass carp (Ctenopharyngodon idellus), in the associated habitat environments (pond water and sediment) and in the ingested food (commercial feed and the reed Phragmites australis) by analysing 16S rDNA sequences from clone libraries. The highest bacterial diversity was observed in the gut content and was determined by the total number of operational taxonomic units, Shannon diversity index (H), Shannon equitability index (EH), Coverage (Cgood) and rarefaction curves calculated from the 16S rDNA gene libraries. Our data indicated that allochthonous gut microbes of grass carp were distinctively different from the corresponding environmental microbes. The pairwise similarity coefficient (Cs) for microbe communities between gut content and ingested food was higher than for those between the gut content and habitats, indicating that the allochthonous microbiota identified in the intestines of grass carp were phylogenetically closer to those in the ingested food than to those in the habitat. Based on our study and previous research, we suggest that the digesta of grass carp harbours a microbiota phylogenetic core of Proteobacteria and Firmicutes and this observation deserves further investigations with respect to a potential pool of probiotics to grass carp.

Effects of dietary antibiotic growth promoter and Saccharomyces cerevisiae fermentation product on production, intestinal bacterial community, and nonspecific immunity of hybrid tilapia (Oreochromis niloticus female × Oreochromis aureus male)1

To investigate the effects of a dietary antibiotic growth promoter (florfenicol) and a Saccharomyces cerevisiae fermentation product (DVAQUA) on growth, G:F, daily feed intake, intestinal bacterial community, and nonspecific immunity of hybrid tilapia (Oreochromis niloticus ♀ × Oreochromis aureus ♂), a 16-wk feeding trial was conducted in a recirculating aquaculture system. Four feeding regimens were evaluated: control, dietary florenicol (0.02 g/kg; 16 wk), dietary DVAQUA (0.5 g/kg; 16 wk), and sequential use of florenicol (0.02 g/kg; 8 wk), and DVAQUA (0.5 g/kg; 8 wk). Each regimen had 4 replicate tanks (0.5 × 0.5 × 0.5 m) and each tank contained 12 fish (initial BW: 46.88 ± 0.38 g). Dietary florfenicol improved growth (P = 0.089), G:F (P = 0.036), and serum complement component concentrations (P < 0.001) of hybrid tilapia. However, the compound decreased the estimated intestinal bacterial count estimated by rpoB quantitative PCR (P < 0.001) and bacterial diversity (visual band numbers, Shannon diversity index, and Shannon equitability index based on 16S rDNA V3 denaturing gradient gel electrophoresis fingerprints) compared with the control. Although sequential use of florfenicol and DVAQUA improved growth and G:F numerically to a similar extent as dietary florfenicol, and increased intestinal bacterial count to normal quantities, the sequential use of florenicol and DVAQUA decreased intestinal bacterial diversity (visual band numbers, Shannon diversity index, and Shannon equitability index) as well as serum complement component concentrations (P < 0.001) compared with their respective use and the control. These findings might be negatively related to disease control and host defense, and the sequential use of florenicol and DVAQUA should be practiced with caution. Feeding DAVQUA to the fish improved nonspecific immunity and increased intestinal bacterial count and bacterial diversity, but further research, including challenge studies, should be conducted before recommendation of DVAQUA supplementation to hybrid tilapia diets.

Role of abiotic and biotic factors in structuring the metazoan plankton community in a lowland river

AbstractWater and quantitative zooplankton samples were collected at approximately monthly intervals from June 2000 to June 2002 in the middle section of the Po River (Northern Italy). Highly variable hydrological conditions were observed in the 2 years, with river flow varying approximately between 400 and 9300 m3 s−1. Dissolved inorganic nitrogen (DIN) usually decreased at higher river discharges. Autotrophic production was limited by phosphorus availability during the growing period (May–October); no significant adverse effect of zooplankton grazing upon algal biomass was detected. A total of 161 zooplankton taxa were found. The records of the rotifers Lecane incospicua, L. cornuta, Proales sigmoidea, Cephalodella limosa, and of the cladoceran Phrixura leei were new for Italy. Rotifers strikingly were the most abundant group over the entire sampling period. Zooplankton abundance was positively correlated to water temperature and chlorophyll‐a concentration, and only in warmer months inversely correlated to river flow. Species of the genus Brachionus were responsible for the two density peaks (&gt;1000 ind L−1) of the rotifer taxocoenosis observed in July 2000 and August 2001, coinciding with chlorophyll‐a peaks higher than 50 µg L−1 and minima of Shannon equitability index. Water temperature, chlorophyll‐a, and soluble reactive phosphorus (SRP) were found to be the most important variables in explaining the observed rotifer assemblages by Canonical Correspondence Analysis. A simple descriptive model is proposed to represent the combined influence of abiotic constraints and biotic interactions on the zooplankton abundance and diversity in the middle reach of the Po River. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Resistance of Sharon Goatgrass (Aegilops sharonensis) to Fungal Diseases of Wheat.

Sharon goatgrass (Aegilops sharonensis) is a wild relative of wheat that is native to Israel and Lebanon. The importance of A. sharonensis as a source of new resistance genes for wheat warrants additional research on the characterization of accessions for economically important genes. Thus, the objectives of this study were to evaluate a collection of A. sharonensis accessions for resistance to seven important fungal diseases of wheat and assess the phenotypic diversity of the germplasm for disease reaction. The frequency of resistance in A. sharonensis was highest to powdery mildew (79 to 83%) and leaf rust (60 to 77%). Resistance to stem rust also was common, although the percentage of resistant accessions varied markedly depending on the pathogen race-from 13% to race TTTT to 72% to race QCCJ. The frequency of resistance was intermediate to stripe rust (45%) and low to tan spot (15 to 29%) and spot blotch (0 to 34%). None of the A. sharonensis accessions was resistant to Fusarium head blight. Many of the accessions tested exhibited heterogeneous reactions (i.e., had both resistant and susceptible plants) to one or more of the diseases, suggesting that heterozygosity may be present at some resistance loci. Substantial variation was observed in the level of diversity to individual diseases because Shannon's Equitability index ranged from 0.116 (for Fusarium head blight) to 0.994 (for tan spot). A high level of diversity was found both between and within collection sites. Moreover, differences in the geographic distribution of resistant accessions were observed. For example, accessions from northern Israel generally were less diverse and less resistant to leaf rust and stripe rust than accessions from more southern locations. Four A. sharonensis accessions were highly resistant to most of the diseases evaluated and may provide a source of unique resistance genes for introgression into cultivated wheat.

Elevational gradients of species diversity, breeding system and floral traits of orchid species on Réunion Island

AbstractAim This research investigates changes in orchid species composition and diversity, plant breeding system and floral traits along an elevational gradient spanning 2300 m (200–2500 m).Location The study was conducted on Réunion Island (Mascarene Islands, Indian Ocean).Methods Data on the distribution of 135 orchid species from 35 genera were gathered from 121 localities situated between 200 and 2500 m a.s.l. For each locality, 500‐m transects were walked and each orchid species was recorded. Measures of species diversity (species richness, a modified Shannon diversity index and the modified Shannon equitability index) were related to altitude using ordinary least‐squares regression. Species turnover and elevational gradients in species composition were determined by: (1) relating scores of detrended correspondence analysis to altitude using ordinary least‐squares regression, and (2) relating Sørensen similarity indices to differences in altitude using Mantel tests. Finally, the average proportion of species displaying similar floral traits or showing the same breeding system were compared among altitudinal zones.Results Species richness per transect ranged from 1 to 36 species (mean 14.3) and decreased significantly with increasing altitude. Similarly, species evenness decreased significantly with increasing altitude. Around 50% of all orchid species were rare (occurred in fewer than 5% of all localities), and only a few occurred in more than 50% of all localities. Orchid species composition changed continuously with altitude, indicating turnover of species with increasing altitude. Analogously, orchid breeding systems and floral traits also changed with altitude. Relatively more auto‐pollinating species were found at high altitudes compared with mid‐ and low‐altitude sites where animal‐pollinated species were most abundant. Species characterized by a cleistogamous pollination system were found almost exclusively in high‐altitude sites, whereas the proportion of species displaying floral traits related to pollination by long‐tongued moths (sphinx) and flies sharply decreased with increasing altitude.Main conclusions Environmental conditions associated with altitude exert a large influence on orchid species composition and the distribution of orchid breeding systems. Our results revealed a high proportion of auto‐pollinating species, and confirm earlier findings that auto‐pollinating species are more frequent in high‐altitude sites.

Isopod gut microflora parameters as endpoints in toxicity studies

AbstractTerrestrial isopods Porcellio scaber (Crustacea) were fed for five weeks on food contaminated by 250, 500, or 1,000 μg of Cd/g or for 10 d on diets with 50 or 250 μg Cd/g food. In both experiments, fecal production rate and colony forming units (CFUs) in the guts were determined. In addition, at the end of 10 d, each distinct colony morphotype obtained in gut samples was purified and characterized. Isolates were separated into 25 groups based on morphological and biochemical characteristics. These bacterial groups were used as units for calculating Shannon equitability indices (J) for each gut. The relative frequencies of the 25 bacterial units were determined in both cadmium groups (50 or 250 μg Cd/g food) and in the control. Cadmium‐induced perturbations observed in the gut microbial communities were (1) increased number of morphologically distinct bacterial isolates in the group fed low‐cadmium‐dosed food (50 μg Cd/g) and reduced number of morphologically distinct bacterial isolates in the group fed high‐cadmium‐dosed food (250 μg Cd/g) compared with the control, (2) increased or decreased relative frequencies of almost all 25 bacterial units provoked by cadmium‐contaminated food, (3) time‐dependent increased numbers of gut CFUs in cadmium‐fed animals (dose dependence was not observed), and (4) significant changes in community structure described by Shannon equitability indices at lower levels of food contamination (50 μg Cd/g) only. Gut microflora parameters are proposed as additional endpoints in the standardized single‐species toxicity test with the terrestrial isopod P. scaber as a means of increasing the ecological relevance of the results.

Isopod gut microflora parameters as endpoints in toxicity studies.

Terrestrial isopods Porcellio scaber (Crustacea) were fed for five weeks on food contaminated by 250, 500, or 1,000 microg of Cd/g or for 10 d on diets with 50 or 250 microg Cd/g food. In both experiments, fecal production rate and colony forming units (CFUs) in the guts were determined. In addition, at the end of 10 d, each distinct colony morphotype obtained in gut samples was purified and characterized. Isolates were separated into 25 groups based on morphological and biochemical characteristics. These bacterial groups were used as units for calculating Shannon equitability indices (J) for each gut. The relative frequencies of the 25 bacterial units were determined in both cadmium groups (50 or 250 microg Cd/g food) and in the control. Cadmium-induced perturbations observed in the gut microbial communities were (1) increased number of morphologically distinct bacterial isolates in the group fed low-cadmium-dosed food (50 microg Cd/g) and reduced number of morphologically distinct bacterial isolates in the group fed high-cadmium-dosed food (250 microg Cd/g) compared with the control, (2) increased or decreased relative frequencies of almost all 25 bacterial units provoked by cadmium-contaminated food, (3) time-dependent increased numbers of gut CFUs in cadmium-fed animals (dose dependence was not observed), and (4) significant changes in community structure described by Shannon equitability indices at lower levels of food contamination (50 microg Cd/g) only. Gut microflora parameters are proposed as additional endpoints in the standardized single-species toxicity test with the terrestrial isopod P. scaber as a means of increasing the ecological relevance of the results.