AZTI Marine Biotic Index Research Articles

Setting reference conditions for mesohaline and oligohaline macroinvertebrate communities sensu WFD: Helping to define achievable scenarios in basin management plans

The Water Framework Directive requires all Member States to achieve good ecological quality status for all waters (e.g., transitional waters). For that purpose, Member States must assess water bodies based on information on the Biological Quality Elements listed for each of them (e.g., benthic macroinvertebrates). However, the production of such a quality status classification (high, good, moderate, poor, bad) requires high reference conditions (associated with the absence of, or very low, human pressure) against which the deviation of the samples to be assessed can be measured. In transitional waters, upper stretches have seldom been included in monitoring activities, resulting in very little knowledge of mesohaline and oligohaline areas, which means further difficulty when defining the required reference conditions for these zones.Regarding the benthic macroinvertebrates, large datasets from the mesohaline and oligohaline stretches of the Mondego estuary (four seasons, five years, environmental parameters, density and biomass data) were used to estimate high reference condition values. In terms of environmental conditions, summer was identified as the most stable season and the most suitable for defining reference conditions for selected ecological indicators. For each indicator, the multivariate linear model expressing the best correlation with measured environmental parameters was selected. These models were used afterwards, by replacing the environmental parameters in those equations with their high reference values, to calculate the reference condition for each ecological indicator.Generally, macrobenthic communities within each stretch changed over the years, being mainly influenced by salinity and sediment organic matter. In both stretches, only a few taxa occurred and two species (the amphipod Corophium multisetosum and the bivalve Corbicula fluminea) were clearly dominant. Diversity values (for Margalef, Shannon and ES50 – Hurlbert indices) were low in both stretches, although higher in the mesohaline, and for the most part the ecological condition was low (AMBI – AZTI Marine Biotic Index, MEDDOC – Mediterranean Occidental index, BENTIX biotic index, BO2A – Benthic Opportunistic Annelida Amphipod index). On the whole, the RC estimated for each index followed the same trend, being different for each stretch and below those found for lower sections of the estuary in other surveys.

Can biotic indicators distinguish between natural and anthropogenic environmental stress in estuaries?

Because estuaries are naturally stressed, due to variations in salinity, organic loadings, sediment stability and oxygen concentrations over both spatial and temporal scales, it is difficult both to set baseline reference conditions and to distinguish between natural and anthropogenic environmental stresses. This contrasts with the situation in marine coastal and offshore locations. A very large benthic macroinvertebrate dataset and matching concentrations for seven toxic heavy metals (i.e. Cr, Ni, Cu, Zn, Cd, Hg and Pb), compiled over three years as part of the UK's National Marine Monitoring Programme (NMMP) for 27 subtidal sites in 16 estuaries and 34 coastal marine sites in the United Kingdom, have been analysed. The results demonstrate that species composition and most benthic biotic indicators (number of taxa, overall density, Shannon–Wiener diversity, Simpson's index and AZTI's Marine Biotic Index [AMBI]) for sites in estuarine and coastal areas were significantly different, reflecting natural differences between these two environments. Shannon–Wiener diversity and AMBI were not significantly correlated either with overall heavy metal contaminant loadings or with individual heavy metal concentrations (‘normalized’ as heavy metal/aluminium ratios) in estuaries. In contrast, average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) did not differ significantly between estuarine and coastal environments, i.e. they were unaffected by natural differences between these two environments, but both were significantly correlated with overall heavy metal concentrations. Furthermore, Δ+ was correlated significantly with the Cu, Zn, Cd, Hg and Pb concentrations and Λ+ was correlated significantly with the Cr, Ni, Cu, Cd and Hg concentrations. Thus, one or both of these two taxonomic distinctness indices are significantly correlated with the concentrations for each of these seven heavy metals. These taxonomic distinctness indices are therefore considered appropriate indicators of anthropogenic disturbance in estuaries, as they allow a regional reference condition to be set from which significant departures can then be determined.

Ecological quality assessment based on macrobenthic assemblages indices along West Port, Malaysia coast

Macrobenthic communities are useful biological indicators for monitoring the health status of marine environments. In this context, biological indices have been widely developed based on macrobenthic communities in order to distinguish the ecological status of marine environments. In this study, results from several indices such as Shannon–Weiner, AZTI Marine Biotic Index, Multimetric AZTI Marine Biotic Index, and BENTIX were compared and evaluated. The effects of environmental factors on the benthic communities were also studied. Results from these indices revealed significant differences in ecological status between sampling stations, which were probably due to the different structures of benthic communities and their state successions. The results consistently emphasized the anthropogenic effects and natural variability caused by these variations in spatial scales.

원문만 패류양식어장에 서식하는 대형저서동물의 춘계와 하계의 군집구조 및 건강도 평가

This study investigated the community structure and health assessment of macrobenthic assemblages in Wonmun Bay, in the southern coast of Korea. The total number of species and mean density were 170 species and <TEX>$1,269\;indivuduals/m^2$</TEX>, respectively. The major dominant species were the bivalve Theora fragilis (<TEX>$230{\pm}446\;indivuduals/m^2$</TEX>) and the polychaetes Lumbrineris longifolia (<TEX>$180{\pm}339\;indivuduals/m^2$</TEX>), Sigambra tentaculata (<TEX>$124{\pm}153\;indivuduals/m^2$</TEX>), Paraprionospio patiens (<TEX>$104{\pm}293\;indivuduals/m^2$</TEX>) and Capitella capitata (<TEX>$82{\pm}223\;indivuduals/m^2$</TEX>). Community statistics [cluster analysis and nonmetric multidimentional scaling (NMDS) ordination] revealed that the macrobenthic community structure in the study area was classified into three station groups for both seasons. Several biotic indices based on macrobenthic communities have been developed to assess the ecological quality of coastal ecosystems. In this study, the ecological status was assessed by four biotic indices Shannon's H', the AZTI Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI) and the Ecological Conservation Index (ECI). The ecological statuses of the macrobenthic communities in Wonmun Bay were poorer in the summer than in the spring. The results of the present study indicate that three biotic indices ( i.e.; Shannon's H', M-AMBI and ECI ) were better correlated with bottom dissolved oxygen than the AMBI in Wonmun Bay.

천수만에 서식하는 대형저서동물의 춘계와 하계의 군집구조 및 건강도 평가

This study was performed to investigate the community structure and health assessment of macrobenthic assemblages in Cheonsu Bay, West Coast of Korea. Total species number was 224 and mean density was 1,940 ind./m 2 , both of which were dominated by polychaete worms (111 species and 1,213 ind./m 2 ). In terms of density, the major dominant species were the bivalve Theora fragilis (280±213 ind./m 2 ), the polychaetes Heteromastus filiformis (254±218 ind./m 2 ), Lumbrineris longifolia (216±41 ind./m 2 ), Mediomastus californiensis (158±97 ind./m 2 ) and the amphipod Eriopisella sechellensis (167±100 ind./m 2 ). As a result of community statistics (cluster analysis and nMDS ordination), the macrobenthic community structure was classified two major groups (inner and mouth of bay) and two stations (station 2 near Ganwol dyke in spring and summer). The Benthic Pollution Index (BPI) and AZTI's Marine Biotic Index (AMBI) were applied to assess the benthic ecological status. During the sampling periods, the BPI Index values varied between 11 (bad status) and 92 (high status). On the other hand, the AMBI Index values was ranged between 1.34 (good status) and 4.39 (poor sta

Effect of ecological group classification schemes on performance of the AMBI benthic index in US coastal waters

The AZTI Marine Biotic Index (AMBI) requires less geographically-specific calibration than other benthic indices, but has not performed as well in US coastal waters as it has in the European waters for which it was originally developed. Here we examine the extent of improvement in index performance when the Ecological Group (EG) classifications on which AMBI is based are derived using local expertise. Twenty-three US benthic experts developed EG scores for each of three regions in the United States, as well as for the US as a whole. Index performance was then compared using: (1) EG scores specific to a region, (2) national EG scores, (3) national EG scores supplemented with standard international EG scores for taxa that the US experts were not able to make assignments, and (4) standard international EG scores. Performance of each scheme was evaluated by diagnosis of condition at pre-defined good/bad sites, concordance with existing local benthic indices, and independence from natural environmental gradients. The AMBI performed best when using the national EG assignments augmented with standard international EG values. The AMBI using this hybrid EG scheme performed well in differentiating apriori good and bad sites (>80% correct classification rate) and AMBI scores were both concordant and correlated (rs=0.4–0.7) with those of existing local indices. Nearly all of the results suggest that assigning the EG values in the framework of local biogeographic conditions produced a better-performing version of AMBI. The improved index performance, however, was tempered with apparent biases in score distribution. The AMBI, regardless of EG scheme, tended to compress ratings away from the extremes and toward the moderate condition and there was a bias with salinity, where high quality sites received increasingly poorer condition scores with decreasing salinity.

Assessing the benthic habitat quality in the Huanghe (Yellow River) Estuary and its adjacent areas using AMBI and M-AMBI

The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe (Yellow River) Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality (BHQ) of the Huanghe Estuary and its adjacent areas is conducted, using AZTI’s Marine Biotic Index (AMBI) and multivariate AMBI (M-AMBI) based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were “high” or “good”, because the ecological group I (EGI) and the ecological group II (EGII) were dominant macrobenthic ecological groups in the research area. Owing to a low species’ richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced (undisturbed or slightly disturbed) stations. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are “high”, and 61% of the stations are slightly disturbed and those of the BHQ are “good”, and the rest are meanly disturbed and those of the BHQ are “moderate”.

Assessing benthic ecological status of urban sandy beaches (Northeast Atlantic, Morocco) using M-AMBI

Rapid coastal development in recent decades has resulted in littoral environmental degradation in Morocco. Casablanca, considered as the economic metropolis driver of the country, is highly impacted by the excess of pollution rejected directly on its shores. The present study aimed at assessing, for the first time, the ecological status (ES) of urban sandy beaches using the Multivariate AZTI Marine Biotic Index (M-AMBI). Five sampling urban beaches around Casablanca [Petite Zenata (PZ), Grande Zenata (GZ), Ain Diab (AD), Sidi Abderrahmane (SD) and Sidi Rahal (SR)] were chosen so as to include a variety of stresses. They were monitored from May 2009 to April 2010 for water and sediment physico-chemical characteristics as well as for their benthic macrofauna in the saturation zone.According to water and sediment analyses, the overall pattern of environmental quality status revealed that wastewater and sewage are significant sources of urban sandy beaches pollution around Casablanca. In the first place, the PZ beach, and, secondarily, the GZ beach were evidenced as the most impacted locations. Both beaches presented high organic matter levels and faecal contamination in the water column that exceeded the human health standards. Furthermore, the total organic carbon (TOC) concentrations in sediment highlighted an evident organic enrichment, mainly at PZ beach (TOC>20%). However, metal contamination was more evident in sediment than in the water column and exceeded rarely the Severe Effect Level.The benthic macrofauna was composed of a total of 28 taxa and revealed intra- and inter-beaches variations. Reference Conditions for the M-AMBI were selected according to historical reference condition combined to expert judgment based on historical data. Globally, M-AMBI worked well on assessing the ES under eutrophication stress due to excess nutrients input. The worst ES was recorded at PZ beach with most of time in bad ES. However, the spatio-temporal changes in the ES were not usually related to the various stressors despite the significant correlations observed between the M-AMBI and some physicochemical features of water and sediment. Sandy beaches are regarded as naturally stressed environments. The wide variations in their environmental conditions make it difficult to discern natural from human-induced changes. Therefore, the “Sandy Beach Quality Paradox” concept is proposed and will certainly be evolved concurrently with the assessment of the ES of sandy beaches. This first attempt on assessing the status of urban sandy beaches of Northeastern Atlantic (Morocco) should be considered as a first step towards more comprehensive and robust evaluation of the impact of human pressures on sandy beaches.

Amphipods from marine cave sediments of the southern Iberian Peninsula: diversity and ecological distribution

Summary: The present study explores the amphipod assemblages of six marine caves on the Mediterranean coast of southern Spain. Replicate samples were taken both inside and outside each marine cave in order to characterize the amphipod fauna and the physicochemical properties of the sediment. As a result, 44 amphipods species were identified. The high number of species found in a relatively limited area highlighted the richness of the Alboran Sea fauna, which is mainly due to the mixture of species from different biogeographic areas. Harpinia genus was the dominant amphipod taxa inside marine caves and Perioculodes longimanus was also very abundant in the caverns. On the other hand, external communities were dominated by Siphonoecetes sabatieri, Metaphoxus fultoni and Photis longipes. There was a high degree of variability in both the internal and the external stations. Only the external station situated at low-medium depth showed a relatively homogeneous amphipod assemblage. The structure and behaviour of soft-bottom communities inside marine caves is difficult to predict because their environmental conditions depend on a particular combination of factors such as topography, depth and orientation. Therefore, no constant patterns were observed for species richness, Shannon diversity and abundance of amphipods in marine caves in comparison with open habitats. According to canonical correspondence analysis, sediment granulometry, organic matter and nitrogen concentration were the parameters that best explained the distribution of amphipods. Species were also classified by their tolerance to environmental pollution according to criteria followed by the Azti Marine Biotic Index and the BENTIX index. The great abundance of sensitive species at both the internal and external stations indicates the good ecological quality of the soft bottom studied. However, the suitability of biotic indices in marine caves should be tested in future studies.

Biomarkers: Are realism and control mutually exclusive in integrated pollution assessment?

The conventional view of pollution monitoring is that any choice is a trade-off between realism and precision, as the control over confounding variables decreases with the increasing degree of organization of the test system.Dublin Bay is subject to considerable anthropogenic pressures and there have been many attempts to quantify the status of the system at organizational levels from DNA strand breaks (Comet) to the system itself (Ecological Network analysis, ENA).Using Dublin Bay as an example, the data show there was considerable variability at all levels of organization. At intracellular level, Lysosome Membrane Stability (LMS, assessed by Neutral Red Retention, NRR) varied almost 4-fold with season and individual condition, while the community level AZTI Marine biotic Index (AMBI) had a similar range within a single, supposedly homogeneous, site. Overall, there was no evidence that biomarkers of the lower levels of organisation reduced the variability of the measure, despite the extra control over influencing variables, nor was there any evidence that variability was additive at higher levels of organisation.This poses problems for management, especially given the fixed limits of Ecological Quality Standards (EQSs). Clearly while the integrated approach to pollution monitoring does offer the potential to link effects across the organizational range, it should also be possible to improve their capability by widening the database for reference values, particularly at the higher level of organization, and by process models, including the confounding variables found in the field, for those at lower level.

Towards a suitable ecological status assessment of highly stratified mediterranean estuaries: A comparison of benthic invertebrate fauna indices

Biotic indices developed to assess the ecological status of coastal waters according to the European Water Framework Directive (WFD) often show discrepancies when they are applied in transitional environments. Although several indices have been widely used in transitional waters throughout Europe, there is still a lack of knowledge about their suitability assessing ecological status. We evaluated the performance of most common used biotic indices and community parameters (e.g. Multivariate AZTI's Marine Biotic Index (M-AMBI), BENTIX, Benthic Opportunistic Polychaetes Amphipods index (BOPA), diversity indices, species richness, abundance) that have been proposed in the scope of WFD, using data of macroinvertebrate community coming from a special case of transitional water body, the highly stratified Ebro estuary. Additionally, we tested their ability to respond to the main pressures affecting the Ebro estuary, the hydrological alteration due to regulation and the pollution pressure due to nutrient enrichment. Estimation of hydrological alteration was based on flow historical data (period from 1913 to 1963), that we assumed as 'hydrological reference conditions' for Ebro estuary. Pollution pressure was estimated by means of PCA analysis including organic and nutrient enrichment related variables, expressed as a synthetic index by PCA factor scores extraction. All the community parameters were able to detect changes in macrofauna composition along the estuarine gradients and were able to differentiate between the impoverished stations and the healthier ones. Regarding indices, the ratings were contradictory and only M-AMBI classified the stations in the correct way. Strong significant correlations were found between indices and metrics and the calculated pressures; nevertheless, these correlations showed a paradoxical result, since increasing hydrological alteration benefited the macrofauna, achieving great complexity. Other identified limitations of biotic indices were the opposite classifications, overestimation of ecological status and low resolution ability. We conclude that for transitional water ecosystems, where each water body has particular characteristics, is difficult the use of 'common biological' assessment tools as the results of this study, among others (more details in discussion section), have demonstrated. Nevertheless, M-AMBI seemed to work in the correct way, so further investigation about its use for transitional waters is necessary. The development of new strategies such as the use of historical data, the use of metrics as a complement for the assessment could be a reliable alternative.

The impact assessment of cage aquaculture on benthic communities along the south eastern Black Sea

The present study was conducted to examine the impact of cage aquaculture on benthic communities in coastal areas (depth 25 to 50 m) from fish farming operations located along the southeastern Black Sea (Ordu-Persembe, Trabzon-Yomra and Rize central). Sampling was conducted seasonally from April 2007 to 2009. Sediment samples were taken using Ekman Grab (box core- 0.04 m 2 ). Temperature, salinity, and water velocity were periodically measured to determine influencing sedimentary organic matter in the sediment, oxygenation, and anoxic conditions. In addition, grain size of sediment, organic carbon content, and distribution of benthic communities were investigated. In order to determine benthic impact of fish farms on the region, Shannon – Wiener diversity index (H’), AMBI (AZTI Marine Biotic Index) and M-AMBI (Multivariate- Marine Biotic Index) indices were used. Results of current study showed that benthic zone ecological quality of stations with number 01, 02, 03, and 04 at Ordu-Persembefish-farming habitat was found to be very low. In autumn 2008, there were 3 species which belonged to Capitella capitata (844 individuals/m 2 ), Capitella sp. (133 individuals/m 2 ), and Heteromastus filliformis (311 individuals/m 2 ) at OP-01 station. In addition, the impact of Trabzon-Yomra fish-farming activity on benthic communities was low. The degree of exposure for Rize fish-farming area in all seasons was quite low, which was not a significant negative impact.

AMBI and M-AMBI indices as a robust tool for assessing the effluent stressed ecosystem in Nandgaon Coastal waters, Maharashtra, India

Due to industrialization, estuarine and coastal water receive a bulk amount of effluent/pollutant from various industries; therefore assessment of the health of the ecosystem is very much essential. Although the AMBI (Azti Marine Biotic index) indices have been used to predict the quality of European waters, no implementation of WFD (Water Framework Directives) has been made on Indian waters so far. In view of that, the present study was undertaken to assess the health of a stressed ecosystem of Nandgaon coastal waters, India. The results of AMBI were highly correlated with the total organic carbon in the heavily disturbed area with ecological groups IV and V. Thus, the result of the present study indicates that the AMBI indices could be useful to detect industrial effluent effects in Indian coastal waters and will provide a motivation to extend this kind of analysis over the entire coastal line of India.

Is there a significant relationship between the benthic status of an area, determined by two broadly-used indices, and best professional judgment?

Two benthic indices to assess the quality status (the AZTI's Marine Biotic Index (AMBI) and multivariate-AMBI (M-AMBI)) are being used extensively in different habitats worldwide. We try to interpret what is behind these indices making them suitable for different habitats. To demonstrate that, we used best professional judgment (BPJ), applying it to a dataset from southern Chile, to determine the criteria proposed by 12 experts in assessing the status. The experts were provided with raw species abundance data, from 12 stations within a gradient of disturbance, from unaffected to severely affected. There was a very good agreement among experts (kappa values 0.72–0.77), with highly significant (p<0.001) correlation between BPJ and AMBI and M-AMBI classifications, and an agreement of 76.4% and 81.9%, respectively. When comparing BPJ in Chile with other results in Europe, USA and northern Africa, similar patterns can be identified: (i) the number of criteria identified for classification is very high (range 7–12); (ii) the experts use several criteria together in the BPJ assessment; and (iii) the rank of the most important criteria is indicator species, richness, and diversity/dominance. These criteria are included in indices such as AMBI and M-AMBI. Hence, although experts are classifying samples subjectively when applying BPJ, they are corroborated in their opinions when using such indices. This fact can explain why these indices are so widely used.

A critical analysis on the response of macroinvertebrate communities along disturbance gradients: description of MEDOCC (MEDiterranean OCCidental) index

AbstractMacroinvertebrate communities inhabiting shallow sandy bottoms from Catalonia and Balearic Islands coastal waters (Western Mediterranean) were used to develop the Mediterranean Occidental (MEDOCC) index, a new methodology to assess the ecological status (ES) according to Water Framework Directive (WFD) requirements. The dominance pattern of four ecological groups (EG; sensitive, indifferent, tolerant and opportunistic organisms) was studied along a disturbance gradient. Sensitive taxa were present in disturbed situations and tolerant species were related to opportunistic taxa. The thresholds between ES were scaled according to the shifts in the dominance pattern of the EGs. The distribution of the EGs along the gradient of disturbance may vary depending on the studied communities, thus influencing the boundaries defining the ES. With the development of the MEDOCC index it is shown that analysing the response of the communities to the increasing gradient of disturbance is critical to enable an accurate proposal for boundary setting to be made, and to improve the applicability of the indices. AMBI (AZTI Marine Biotic Index), Bentix (Biotic Index), and MEDOCC indices were applied to the dataset to compare the ES obtained.

Environmental Status Assessment Using DNA Metabarcoding: Towards a Genetics Based Marine Biotic Index (gAMBI)

Marine ecosystem protection and conservation initiatives rely on the assessment of ecological integrity and health status of marine environments. The AZTI's Marine Biotic Index (AMBI), which consists on using macroinvertebrate diversity as indicator of ecosystem health, is used worldwide for this purpose. Yet, this index requires taxonomic assignment of specimens, which typically involves a time and resource consuming visual identification of each sample. DNA barcoding or metabarcoding are potential harmonized, faster and cheaper alternatives for species identification, although the suitability of these methods for easing the implementation of the AMBI is yet to be evaluated. Here, we analyze the requirements for the implementation of a genetics based AMBI (gAMBI), and show, using available sequence data, that information about presence/absence of the most frequently occurring species provides accurate AMBI values. Our results set the basics for the implementation of the gAMBI, which has direct implications for a faster and cheaper marine monitoring and health status assessment.

Evaluation of the ecological status with benthic indices in the coastal system: the case of Bohai Bay (China)

Based on biologic and environmental materials collected from coastal areas of Bohai Bay (China) in April, 2008, three biotic indices (AZTI’s Marine Biotic Index (AMBI), Shannon-Wiener Index and W-statistic) were applied together to evaluate the ecological status of the sampling area. The results showed a clear spatial gradient from a worse ecological status in the near-shore areas (especially around Haihe and Jiyun River Estuaries) to a better status in the offshore areas. While all the three indices could assist decision makers in visualizing spatial changes of organic pollutants in Bohai Bay, two indices, i. e., AMBI and Shannon-Wiener index, were effective in distinguishing sites from Haihe River Estuary, Jiyun River Estuary and other area. However, W-statistic can’t tell the differences between estuaries and other area. It would be explained that organic pollutants and/or other environmental stresses in Bohai Bay were not strong enough to reduce the size of macrozoobenthos, which may cause both of the abundance and biomass curves crossed. To our knowledge, this is the first time that several benthic indices were used to assess the benthic ecological status in Bohai Bay, which gave the similar results. Furthermore, there is indication that the ecological status is related to excess input of wastewater along main rivers and outlets. In a word, AMBI, Shannon-Wiener Index and W-statistic could be able to assess the benthic ecological status of Bohai Bay under the organic pollutants pressure.

Assessing benthic ecological status in coastal area near Changjiang River estuary using AMBI and M-AMBI

The Changjiang (Yangtze) River estuary has been subject to a variety of anthropogenic pressures in recent decades. To assess the ecological health of the coastal benthic ecosystem adjacent to the estuary, three surveys were conducted in 2005, 2009, and 2010. The AZTI's Marine Biotic Index (AMBI) and multivariate-AMBI (M-AMBI) were used to analyse the benthic ecological status of this coast. The AMBI indicate that the ecological status of the coast adjacent to the Changjiang River estuary was only slightly degraded in all 3 years. In contrast, the M-AMBI indicated that the ecological status was seriously degraded, a result that is most likely due to pollution and eutrophication induced by human activities. The assessment of the coast's ecological status by the AMBI was not in agreement with that of the M-AMBI at some stations because of lower biodiversity values at those sites. The analysis of the two indices integrated with abiotic parameters showed that the M-AMBI could be used as a suitable bio-indicator index to assess the benthic ecological status of the coast adjacent to the Changjiang River estuary. The reference conditions proposed for the coast of the Changjiang River estuary should be further evaluated in future studies. Designation of local species could also provide an important reference for Chinese waters. To improve the reliability of AMBI and M-AMBI, further research into the ecology of local species is required to understand their arrangement in ecological groups.

Assessing benthic health under multiple human pressures in Bohai Bay (China), using density and biomass in calculating AMBI and M‐AMBI

AbstractIn recent decades, China has undergone an impressive development, which has produced increasing human pressures including coastal degradation. Bohai Bay, located in the west of the Bohai Sea (north of China), has been affected by various human pressures, including waste water discharges, land reclamation and oil exploitation. To monitor the effects of these pressures on this ecosystem, benthic macroinvertebrates and environmental variables (dissolved oxygen, nutrients, metals, etc.) were sampled in 2009 and 2011. To assess the ecological status of the benthic communities, the AZTI Marine Biotic Index (AMBI) and multivariate‐AMBI (M‐AMBI) were used, including both density and biomass in the calculation. This is the first research in which M‐AMBI based on biomass (M‐bAMBI) is applied. Both methods showed that the nearshore areas, especially close to the Haihe and Jiyun estuaries, were affected by human pressures, with a clear gradient of decreasing impacts offshore. The ecological status as assessed using density and biomass was quite similar. Significant relationships were also found between both methods and environmental variables. The use of AMBI and M‐AMBI, based upon density and biomass, in assessing the ecological status of water bodies in China seems to be promising.

Tracking environmental stress gradients using three biotic integrity indices: Advantages of a locally-developed traits-based approach

Estuarine and coastal ecosystems are productive and functionally diverse areas that provide a wide range of societal benefits. Along with human exploitative uses comes an array of anthropogenic disturbances that can affect ecological integrity, including changes to the composition and resilience of benthic macroinvertebrate communities. To understand the responses of ecological communities to anthropogenic disturbance and to manage and mitigate effects, indices for assessing the ecological integrity of estuarine and coastal waters have proliferated worldwide. Using data from 84 intertidal sites in Auckland, New Zealand, we evaluated the suitability of two widely used measures of ecological integrity that were developed in USA and Europe, respectively: the Benthic Index of Biotic Integrity (B-IBI) and the AZTI's Marine Biotic Index (AMBI). We then developed a local index based on macrofaunal traits and verified its utility using independent data from >100 additional sites. The local traits based index (TBI), constructed from the richness of macrofaunal taxa in seven functional groups, responded to changes in sediment mud percentage and heavy metal contaminant concentration gradients below international guidelines. The TBI performed better than the indices developed overseas, probably because they were designed to track organic enrichment and hypoxia, which are not the predominant stressors in New Zealand at present. The TBI successfully tracked the stressors that were the most relevant locally and indicated the relative levels of within-group taxonomic richness at various sites. As within-group richness is a component of functional redundancy and ecological resilience, the TBI offers a trifecta of simplicity, robustness and meaningfulness that will facilitate management.