AMBI Index Research Articles

Assessment of macrobenthos in evaluating the restoration effects of artificial mangrove planting on tidal flats in Zhejiang, China.

Artificially planted mangroves are widely used for tidal flat restoration, but their effectiveness in restoring these ecosystems remains unclear. Macrobenthos, as key indicators of tidal flat ecosystem health, can reflect changes in environmental conditions and quality resulting from the introduction of artificial mangroves. This study aimed to investigate the ecological restoration effects of artificially planted mangroves in northern China by surveying macrobenthic communities across four regions in June 2023. We compared the macrobenthic community structures in mangrove zones with those in Spartina alterniflora or unvegetated mudflat control zones by estimating habitat quality indices and community structure analyses. Additionally, we explored the relationship between community structures and environmental factors to identify key drivers of community structure changes. Significant differences in species abundance and biomass were observed across the four regions, with mudflat zones exhibiting the highest values, followed by mangrove and Spartina alterniflora zones. Beta diversity was higher in mangrove zones compared to control zones, driven primarily by turnover components. The AMBI index indicated excellent ecological conditions in 18-year-old mangrove zone on Maoyan Island, while poorer conditions were observed in the mangrove zone of Zhoushan City. Environmental factors, such as sand content, organic carbon content, and elevation, significantly influenced macrobenthic community distribution. Overall, our findings suggest that the 18-year-old mangrove zone on Maoyan Island is ecologically stable and demonstrates significant restoration effects. Using macrobenthos to assess the restoration efficacy of mangroves proves to be both effective and feasible. Furthermore, while the mangroves have successfully established and grown, their long-term survival depends on the active involvement of local stakeholders, highlighting the importance of long-term monitoring and adaptive management strategies.

Ecological quality assessment of estuarine macrobenthic communities using an integrative approach

Macrobenthic communities play a crucial role in the functioning of estuarine ecosystems and serve as bioindicators of environmental quality. This study assessed the ecological quality of an estuarine system using the AMBI and M-AMBI indices. The following parameters were considered: (i) environmental factors (total organic matter, organic carbon, grain size, calcium carbonate), (ii) sediment trace metals (Pb, Zn, Cu, Cr, Co, Ni, Hg, Li, As), (iii) species composition (morphological and molecular identification), and (iv) anthropogenic activities. The results demonstrated notable differences between study areas, reflecting hydrodynamic processes and human activities. The AMBI index indicated that all areas exhibited conditions classified as “slightly disturbed.” However, the composition of the ecological groups and M-AMBI results differed according to the identification method. This approach allowed for a more complete understanding of communities, by integrating the influence of anthropogenic activities on the sediment and macrobenthic communities, highlighting the importance of using both identification methodologies.

Past and present ecological status of the soft bottom macrozoobenthos in a large mediterranean lagoon: any signals of climate change?

Coastal lagoons are transitional areas between land and sea, particularly vulnerable to human impact. The aim of this work was to compare soft bottom macrozoobenthic communities in the Lagoon of Marano and Grado, before (past period: 1993 to 1995) and after the entry into force of the Water Framework Directive-WFD (present period: 2008 to 2021). In the present period higher richness, abundances, and diversity were observed, also considering each water type (euhaline, polihaline and mesohaline) and basin (Marano and Grado) separately. The multivariate analyses also showed differences among periods and water types. According to the AMBI index, most stations were slightly disturbed in all periods and water types, and biocoenotic affinity did not vary significantly. The frequency of echinoderms increased in all water types, whereas the frequency of the polychaete Hedistediversicolor decreased in eu- and polihaline water bodies. These changes can mainly be explained by a general increase in salinity, and therefore probably the result of a marinization process, a decreasing confinement of the lagoon. As the calculation of M-AMBI is derived from AMBI, diversity and richness, this process could lead to a better ecological status sensu WFD, but with the loss of the characteristics and ecological functions of this paralic ecosystem.

Assessing benthic ecological status of Kaduvaiyar estuary, southeast coast of India – Biotic indices approach

The Kaduvaiyar estuary located on the Southeast coast of India in Nagapattinam is facing various human-induced pressures, making it highly affected by human intervention. To evaluate the ecological quality of the Kaduvaiyar estuary and its coastal region, an extensive survey was conducted. The assessment employed different statistical analyses, specifically the AMBI and M-AMBI biotic indices. Through PCA analysis, it was confirmed that St-1 exhibited a higher similarity level of Clay and TOC. Furthermore, the CCA analysis demonstrated the presence of pollution-tolerant and opportunistic polychaetes species, such as Capitella capitata, Cossura coasta, Prionospio pinnata, and Notomastus sp., in St-1 and St-2. These areas showed elevated concentrations of heavy metals, including Fe, Pb, and Mn. This trend was also evident in the w-statistics, where the negative values (−0.08 and −0.105) indicated the highly polluted nature of St-1 and St-2. Substantiating this, the AMBI values (ranging from 1.86 to 4.17) suggested that the stations (St-1 to St-3) were slightly to moderately disturbed. The M-AMBI result (ranging from 0.43 to 0.44) indicated a clear signal of the disturbed nature and moderate ecological condition of stations (St-1, St-2). These stations are located near urban and harbor activities, which likely contribute to their altered state. However, it is essential to subject the reference conditions proposed for the Kaduvaiyar estuary to further evaluation in upcoming studies. Additional research will help gain a more comprehensive understanding of the estuary's ecological health and establish a solid basis for comparison with future assessments.

Seasonal carbonate system vis-à-vis pH and Salinity in selected tropical estuaries: Implications on polychaete diversity and composition towards predicting ecological health

Salinity and pH play a fundamental role in structuring spatial patterns of physical properties, biota, and biogeochemical processes in the estuarine ecosystem. In this study, the influence of salinity-pH gradient and carbonate system on polychaete diversity in Ennore, Uppanar, Vellar, and Kaduvaiyar estuaries was investigated. Water and sediment samples were collected from September 2017 to August 2018. Univariate and multivariate statistical analyses were employed to define ecological status. Temperature, salinity, pH, and partial pressure of carbon-di-oxide varied between 21 and 30°C; 29 and 39 ppt; 7.4 and 8.3; and 89.216 and 1702.558 µatm, respectively. PCA and CCA results revealed that DO, chlorophyll, carbonate species, and sediment TOC have a higher influence on polychaete community structure. Forty-two species such as Ancistrosyllis parva, Cossura coasta, Eunice pennata, Euclymene annandalei, Lumbrineris albidentata, Capitella capitata, Prionospio cirrifera, P. pinnata, P. cirrobranchiata, and Notomastus sp. were found dominantly in all estuaries. Shannon index values ranged between 1.619 (UE-1) and 3.376 (VE-2). Based on these findings, high levels of carbonate species and low pH have a greater impact on polychaete diversity and richness values. The results of the AMBI Index revealed that stations UE-1, UE-2, UE-3 in Uppanar, EC-1, EC-2 in Ennore indicate “moderately disturbed”, while other stations are under the “slightly disturbed” category. This trend was quite evident in M-AMBI as well.

Salud ambiental de playas rocosas en distintos partidos de la Provincia de Buenos Aires

Seas and oceans are impacted by multiple human activities such as urban spills, maritime transport and tourism, among others. These human-generated pressures are directly impacting marine ecosystems, generating pollution, loss of habitat or introduction of exotic species. The objective of this work was to evaluate the environmental health of different beaches belonging to four coastal districts of the Province of Buenos Aires: Necochea, General Alvarado, General Pueyrredón and Mar Chiquita. The study was approached from the variability in the community structure (richness, evenness and diversity), as well as characterizing this structure from the analysis of functional traits and functional diversity indexes (functional features and indexes of functional diversity: functional richness, functional evenness, functional divergence, functional dispersion, functional specialization and quadratic entropy) and environmental quality indexes (AMBI and M-AMBI) in response to different pollution scenarios due to anthropogenic impact (sewage effluent, streams, submarine outfall and beaches for recreational use with no contribution from other sources). Results showed that both the structure and composition of the species assemblage varied significantly between sites. The AMBI and M-AMBI index reflected good environmental health at all beaches, categorizing all sites as ‘good’ (or slightly disturbed), except Quequén site which was categorized as ‘poor’ (or heavily disturbed). This site also presented a composition of the assembly of functional features characteristic of areas that present contamination by organic matter (low relative mobility, deposit feeders, tubular and/or gallery inhabitants and 1st order opportunistic species). The traditional approach reflected the differences in the community structure of the different beaches and the functional approach complemented this result by showing that the functional traits covered by the different species of the benthic communities are mainly related to the contribution of organic matter that each beach receives (streams, rainwater, effluents or submarine emissaries).

Environmental genomics for benthic monitoring of North Sea oil and gas offshore platforms

During the last decade, considerable efforts have been undertaken to achieve a “good ecological status” of European coastal waters and ensuring the development of methodological standards for the evaluation of this status. However, the current routine biomonitoring implicates time-consuming and costly manual sorting and morphological identification of benthic macrofauna. In our study, we tested the performance of environmental DNA metabarcoding targeting microbial communities and meiofauna as an alternative to traditional macrofauna-based monitoring. We focused on environmental impact assessment of offshore oil and gas industry. We used three genetic markers (18S V1V2, 18S V9 and COI) to assess the environmental pressures induced by the platforms. All markers showed patterns of alpha and beta diversity consistent with morphology-based macrofauna analyses, significantly changing along distance gradients from the platforms. The impact of the operational discharges was also detected by the variation of biotic indices values, AMBI index showing the best correlation between morphological and eDNA datasets. Finally, the sediment physicochemical parameters were used to build a local de novo pressure index that served as benchmark to test the potential of a taxonomy-free approach. Our study demonstrates that metabarcoding approach outperforms morphology-based approach and can be used as a cost and time-saving alternative solution to the traditional morphology-based monitoring in order to monitor more efficiently the impact of industrial activities on marine biodiversity.

Assessment of ecological health of Swarnamukhi river estuary, southeast coast of India, through AMBI indices and multivariate tools

A combination of biotic indices, geo-accumulation (Igeo) index, and a multivariate approach were applied to assess the anthropogenic influence on the benthic community at five stations from 2018 to 2019 in the Swarnamukhi river estuary, Nellore, India. Non-metric multidimensional scaling and cluster analysis indicated that the Buckingham canal (BC) station showed azoic conditions and formed a separate cluster. Strong positive factor loadings of Cd (0.96), Al (0.93), Zn (0.91), Fe (0.90), Co (0.89), Cu (0.89), Ni (0.87), Pb (0.85), Cr (0.77), organic matter (0.94), Silt (0.92), and clay (0.93) and negative loading of sand (−0.90) showed the variability in sediment. AMBI results illustrated the disturbance status of each station and classified BC station as ‘extremely disturbed’ class, and M-AMBI assessed the ecological status as ‘bad’. The Igeo index also revealed metal (Cd) contamination. The present study illustrated that the combined approach is effective for ecological assessment of coastal ecosystem.

Responses of functional traits of macrobenthic communities on the presence of Polycyclic Aromatic Hydrocarbons contamination in three tropical estuaries

Estuaries are considered receptors of various contaminants released into the environment, including Polycyclic Aromatic Hydrocarbons (PAH), a ubiquitous contaminant. In this study, the response of subtidal macrofauna in the polyhaline zone of three tropical estuaries was analyzed using a taxonomic approach, multimetric indices, and functional traits, to three different levels of PAH. The estuaries presented distinct degrees of contamination, with PAH directly correlated with mud percentage and organic matter. The considerable variation in granulometry found in the three studied estuaries may indicate complex hydrodynamics, with very different sedimentary characteristics. The community structure showed typical estuarine characteristics, with low diversity and high dominance. The macrofauna was distinct among estuaries, with no shared dominant species and with several species occurring just in one site, with different compositions, although other parameters of the community structure were similar. The AMBI and functional indices performed better than taxonomic indices in separating the areas with different impacts. In the analyzed communities, the functional traits approach demonstrated consolidated patterns in the estuarine environment, such as the predominance of opportunistic species, generally of smaller size and detritivore/depositivore, under conditions of pollution by the organic load. Local characteristics, such as the predominance of suspensivore organisms and relatively more mobility in areas with higher hydrodynamics, provide insight into the community's behavior on natural and anthropogenic stressors. The multivariate taxonomic and functional analyses were complementary, emphasizing the importance of integrating them in these environments diagnosis. Stressed environments need information from the entire data set for a correct assessment of the community.

Macrobenthic communities in the tidal channels around the Gulf of Gabès, Tunisia

A yearlong seasonal survey was carried out during 2016–2017 at 26 stations representing four tidal channels of the north-western part of the Gulf of Gabès (Tunisia). The area studied (characterized by a maximum tidal range of 2.3 m) was subjected to diverse anthropogenic pressures: from the phosphate industry and its metallic pollution, unauthorized bottom trawling in shallow water (known locally as ‘Kiss’), and organic pollution from the nearby urbanized areas. A total of 23,506 invertebrates representing 311 taxa were collected. Dominant taxa were the polychaetes with 51.4% of the individuals collected and 39.3% of the taxa, the amphipods (18.6% and 15.5%), the tanaids (12.3% and 2.6%), and the molluscs (11.5% and 18.3%). The mean annual abundances varied widely from one channel to another: from 300 to 3700 ind·m−2. The stations located in deeper waters exhibited greater variability. Measurements of abundance revealed seasonal changes with maximum values in winter, spring, and lower numbers in summer. Each tidal channel was characterized by specific features in the fauna. The macrofauna were dominated by the polychaete Cirratulus cirratus (mainly in spring) and the amphipod Microdeutopus anomalus (mainly in winter), whilst both of the tanaids, Apseudopsis gabesi (the first sighting reported for the area) and A. mediterraneus, were found to be abundant in winter in at least one of the four channels. Species are mainly deposit feeders, herbivorous and omnivorous. The analyses on spatial and temporal changes of the macrofauna population revealed variations according to the composition of the fauna increasing or falling along the channels and as a function of seasonal changes. In spite of a high level of anthropogenic activities, the Ecological Status (ES) assessment (applying the AMBI and M-AMBI indices) attributed High or Good ES for 10 stations, Moderate ES for 11 stations and five stations showed a poor ES at least during one season. Sampling subtidal stations in the future to survey long-term degradation of such ecosystems of the coastal environment of the Gulf of Gabès in Tunisia is proposed.

Benthic monitoring of oil and gas offshore platforms in the North Sea using environmental DNA metabarcoding.

Since 2010, considerable efforts have been undertaken to monitor the environmental status of European marine waters and ensuring the development of methodological standards for the evaluation of this status. However, the current routine biomonitoring implicates time-consuming and costly manual sorting and morphological identification of benthic macrofauna. Environmental DNA (eDNA) metabarcoding represents an alternative to the traditional monitoring method with very promising results. Here, we tested it further by performing eDNA metabarcoding of benthic eukaryotic communities in the vicinity of two offshore oil and gas platforms in the North Sea. Three different genetic markers (18S V1V2, 18S V9 and COI) were used to assess the environmental pressures induced by the platforms. All markers showed patterns of alpha and beta diversity consistent with morphology-based macrofauna analyses. In particular, the communities' structure inferred from metabarcoding and morphological data significantly changed along distance gradients from the platforms. The impact of the operational discharges was also detected by the variation of biotic index values, AMBI index showing the best correlation between morphological and eDNA data sets. Finally, the sediment physicochemical parameters were used to build a local de novo pressure index that served as benchmark to test the potential of a taxonomy-free approach. Our study demonstrates that metabarcoding approach outperforms morphology-based approach and can be used as a cost and time-saving alternative solution to the traditional morphology-based monitoring in order to monitor more efficiently the impact of industrial activities on marine biodiversity.

Benthic macrofauna as an indicator of Ecological Integrity at an ocean beach with touristic purpose; Playa El Rivero, Punta Del Diablo, Rocha, Uruguay

The concept of Ecological Integrity (EI) refers to the capacity of a place to sustain and maintain the biota in such conditions that allows it to function as a balanced, integrated and adaptive system, and can be derived by comparing present vs. past or spatial reference baseline conditions. Here we assess the EI of Playa El Rivero (34°2’29.35”S, 53∘32’21.14”W) in Punta Del Diablo resort, Uruguay. This 600 m-length, previously unstudied sandy beach is one of the main attractions of the resort, receiving thousands of tourists during summer. Accordingly, conspicuous human impacts are concentrated in the more dissipative end of the beach. In order to derive EI values, a large number of indicators (n=20), including population and community level univariate descriptors for benthic macrofauna, as well as direct indicators of EI (AMBI, M-AMBI and Buckland indices) were assessed and integrated. The distribution of population and community level variables were compared across the along-shore axis with the expected distribution under the Swash Exclusion Hypothesis (SHE) and the Habitat Harshness Hypothesis (HHH), which predict a decrease in richness, biomass and abundance from reflective to dissipative conditions. To derive a global value, an EI value was calculated for population and community levels as well as according to direct impact indicators. EI thus ranged from 1 (no measurable or significant impacts) to 0 (completely dysfunctional system). Integrating all types of indicators, a value of 0.76 was obtained for the beach under study. This value integrates both chronic and putative “press” disturbance occurring during the high tourist season in the period under study and suggests a sub-optimal state (ca. 20% reduction) of the health of the system studied, probably related to the sum of chronic anthropogenic impacts that the beach arc presents. This value is considered as an objective (but probably conservative) reference point in order to evaluate the effectiveness of future management measures.

Comparing structural and functional approaches to distinguish benthic communities from eutrophic and non-eutrophic estuaries

The performance of three approaches for macrobenthic classification in distinguishing communities subjected to different environmental conditions was compared: i) the traditional species-based approach; ii) a tolerance-based approach according to ecological groups of the AMBI index; and iii) a character-based approach using biological traits. We used a hierarchical sampling design including three progressively smaller spatial scales, considering that the environmental degradation influence benthic communities at the larger spatial scale. Despite small-scale spatial variations, all approaches performed similarly, distinguishing eutrophic from non-eutrophic benthic communities as they varied significantly at the larger scale, corresponding to the scale at which human induced changes act. Our results suggest that all three methodological approaches could be used as operational criteria to assess estuarine environmental quality, and despite more meaningful, there is still a degree of subjectivity in functional approaches, associated to the lack of more detailed information on macrofaunal life-cycles and levels of tolerance to disturbance.

Evaluating ecosystem functioning of a long-term dumping site in the Bay of Seine (English Channel)

• Ecopath models after long-term spoil deposit in impacted and non-impacted zones. • A multi-criteria approach is required to detect accurate long-term effects. • Local impact was assessed in spite of 70 years of important dumping deposit. • Indices revealed a high resilience of the Octeville dumping site. The impact of 70 years of dumping harbour dredged material on ecosystem functioning was compared to a control site (non-impacted zone). A combination of indices (Shannon-Wiener diversity, Pielou evenness, BO2A, AMBI benthic indices) and modelling (Ecopath models) generated Ecological Network Analysis indices were used to detect the dumping operations effects. ENA indices showed that dumping operations appear to have a relatively limited impact on the structure and flow pattern of the local food web. In fact, only small variations between the two sites are revealed by a comparison of ENA indices between the impacted and non-impacted zone. This result could be explained by the fact that the Bay of Seine is historically characterized by a high level of human activities, which have led to an increase in resilience through time to face these multiple pressures. AMBI and BO2A indices (of the sediment fauna) did not allow a clear distinction between impacted and non-impacted zone while species richness, abundance, biomass and Shannon-Wiener diversity index values were significantly higher in the non-impacted zone which is in accordance with the small variations of ENA indices between the two zones and revealed a local and limited impact. Our results suggested that a combination of several tools should be used to detect the true impacts and to conduct diagnosis of the ecological status of dumping deposit in a coastal area permanently stressed under natural and anthropogenic forcing.

Multi-marker eDNA metabarcoding survey to assess the environmental impact of three offshore gas platforms in the North Adriatic Sea (Italy)

The environmental DNA (eDNA) metabarcoding represents a new promising tool for biomonitoring and environmental impact assessment. One of the main advantages of eDNA metabarcoding, compared to the traditional morphotaxonomy-based methods, is to provide a more holistic biodiversity information that includes inconspicuous morphologically non-identifiable taxa. Here, we use eDNA metabarcoding to survey marine biodiversity in the vicinity of the three offshore gas platforms in North Adriatic Sea (Italy). We isolated eDNA from 576 water and sediment samples collected at 32 sampling sites situated along four axes at increasing distances from the gas platforms. We obtained about 46 million eDNA sequences for 5 markers from nuclear 18S V1V2, 18S V4, 18S 37F and mitochondrial 16S and COI genes that cover a wide diversity of benthic and planktonic eukaryotes. Our results showed some impact of platform activities on benthic and pelagic communities at very close distance (<50 m), while communities for intermediate (125 m, 250 m, 500 m) and reference (1000 m, 2000 m) sites did not show any particular biodiversity changes that could be related to platforms activities. The most significant community change along the distance gradient was obtained with the 18S V1V2 marker targeting benthic eukaryotes, even though other markers showed similar trends, but to a lesser extent. These results were congruent with the AMBI index inferred from the eDNA sequences assigned to benthic macrofauna. We finally explored the relation between various physicochemical parameters, including hydrocarbons, on benthic community in the case of one of the platforms. Our results showed that these communities were not significantly impacted by most of hydrocarbons, but rather by macro-elements and sediment texture.

Zmiinyi Island Coastal Zone Macrozoobenthos State in 2016-2017

Purpose. To study the state of macrozoobenthos in the Zmiinyi Island coastal zone in 2016-2017. Methods. Standard methods of macrozoobenthos sampling, determination, number and biomass estimation. Results. Results of analysis of biodiversity, structural characteristics and taxonomic composition of macrozoobenthos in the Zmiinyi Island coastal zone have been presented. Seasonal dynamics of its number and biomass has been studied. Assessment of marine environment quality has been performed based on the metrics of macrozoobenthos. Conclusions. Altogether, 132 taxa of benthic invertebrates belonging to 10 biggest taxonomic groups of macrozoobenthos have been identified in the Zmiinyi Island coastal zone in 2016-2017. Analysis of taxonomic composition identified 1 species of Porifera (0.8%), 7 taxa of Cnidaria (5.3%), 3 taxa of Platyhelminthes (2.3%), 1 taxon of Nemertea (0.8%), 3 taxa of Bryzoa (2.3%), 52 taxa of Annelida (39.4%), 25 taxa of Mollusca (18.9%), 35 taxa of Arthropoda (265%), 2 taxa of Echinodermata (1.4%) and 3 taxa of Chordata (2.3%). Out of 132 macrozoobenthos taxa 6 are enlisted in the Red Data Book of Ukraine and 8 – in the Black Sea Red Data Book. Macrozoobenthos number varied from 0.317х104 (27.11.2016) to 16.943х104 (19.08.2016) ind/m2 on soft substrate and from 2.683х104 (17.05.2016) to 30.725х104 (19.08.2016) ind/m2 on rocky substrate; biomass varied from 0.017 (17.05.2017) to 34.857 (19.08.2016) kg/m2 on soft substrate and from 1.531 (27.11.2016) to 46.147 (19.08.2016) kg/m2 on rocky substrate. Maximal development of benthos was registered in summer period. Quality of marine environment on the AMBI and M-AMBI indices was assessed as Good in 21 cases out of 23 and as Moderate in 2 cases 2 out of 23. Mean values of AMBI and M-AMBI indices for different seasons made respectively: May, 2016 – 2.56 and 0.59; August, 2016 – 1.86 and 0.69; November, 2016 – 1.70 and 0.71; June, 2017 – 1.87 and 0.75.

Assessing benthic health of hard substratum macrobenthic community using soft bottom indicators and their relationship with environmental condition

This study aimed to assess ecological quality status of hard substratum macroinvertebrates communities of the Caspian Sea with three ecological indices and their relation with environmental factors. For this purpose benthic communities of the Caspian Sea basin were studied seasonally during 2014 in 8 sampling sites. Temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, silicate and phosphate were measured as environmental factors. The benthic classification indices AMBI, M-AMBI and BENTIX were applied to assess the ecological status of the studied area. Results showed low dissimilarity based on species composition and abundance among seasons, while all seasons discriminated clearly based on environmental factors. In addition, AMBI index was more successful to assess ecological health of hard substratum in the Caspian Sea basin than M-AMBI and BENTIX. Furthermore, AMBI showed high sensitivity to environmental variation. Results indicated that temperature, nitrate, silicate, phosphate and nitrite were the most important factors in the composition and abundance fluctuation of hard substratum macroinvertebrates communities, respectively.

Long-term variability of macrobenthic community in a shallow coastal lagoon (Valli di Comacchio, northern Adriatic): Is community resistant to climate changes?

A time series data of macrobenthic invertebrates of Valli di Comacchio lagoon (northern Adriatic) from 1996 to 2015, was analysed using Biological Traits Analysis, structural indices, AMBI and M-AMBI indices, with a twofold aim to: firstly, test the resilience of the system, and, secondly, test the influence of climate changes, in terms of temperature and precipitation pattern, on macrobenthic dynamics. Along the studied period macrobenthic community showed marked fluctuations, in terms of richness, diversity, biological traits and ecological groups, which could be related with environmental instability of the lagoon. At the same time, a general tendency towards a deterioration of ecological condition of the lagoon was observed, with a general decrease in species richness, diversity, percentage of sensitive species, and a general increase in the proportion of the more opportunistic trait modalities, such as deposit feeders, burrowing, infaunal and short living animals. Increasing yearly temperature explained only a small part of the variability of macrobenthic community, in terms of biological traits and diversity indices, and this was likely due to the effect of natural fluctuations of environmental parameters and anthropogenic disturbance. Nevertheless, all metrics used are consistent in identifying the response of benthic community to a severe disturbance, likely related with the summer heatwave in 2003. Less marked signs of disturbance were observed also in relations to the thermal anomaly of 2012. Biological Traits Analysis combined with more classical structural and ecological indices, proved to be efficient in identifying temporal changes of the community. Our results suggest that the expected increase in frequency, magnitude and duration of heatwaves could pose serious threat to the resilience capacity of lagoonal macrobenthic community.

Unraveling the performance of the benthic index AMBI in a subtropical bay: The effects of data transformations and exclusion of low-reliability sites

We investigated the relationship between the AMBI index and different contamination proxies in an urbanized bay in South America (SE Brazil), and the effect of (a) abundance data transformation and (b) exclusion of low-reliability sites (high SD; low N) on the index' performance. Poor ecological quality and opportunistic species were related to an increase in contaminants concentrations and mud content. Good ecological status and sensitive species (EG I) were mainly related to increased hydrodynamics. Data transformation caused minimal changes to the overall relationships, but exclusion of low-reliability sites improved the relationship between ecological groups and contamination proxies. Our results show that AMBI is robust in detecting effects of different contaminants in the area and reinforce the importance of the index as a tool for coastal management, but local joint efforts are needed to improve and adjust local species classification in ecological groups to improve the index' performance.

Assessing benthic ecological status in subtropical islands, China using AMBI and Bentix indices

Assessment of the ecological quality status is important for environmental protection and management. Benthic sensitivity-based indices have been considered as effective indicators of ecosystem health assessment. In this paper, two benthic sensitivity-based indices, AMBI and Bentix, were used to assess the benthic ecological status of soft-bottom intertidal zones in China's subtropical islands according to the data obtained in spring, 2007. Simultaneously, the assessment results were compared with the sediment quality in order to test the applicability of the indices for island eco-environmental quality assessment. The results showed that 246 species of macrobenthos were identified in the sampling sites. In the intertidal zone of Meizhou Island, dominant species were tolerant, which accounted for 58.7% of the total individuals. In the other intertidal transects, the dominant species were sensitive, but the percentages of tolerant species were high in the intertidal zone of estuarine islands. The results also showed that the benthic ecological status of most intertidal zones studied was high or good, except for the middle tidal zone of Meizhou Island where it was moderate. The two biotic indices were generally correlated with the contents of heavy metals and petroleum in the sediments, which indicated that the two indices could be used to detect the environmental changes related to pollution in a wide range. However, it seems that the AMBI assessment results more reasonably approximated those of the concurrent sediment quality survey than the performance of Bentix.