M-AMBI Indices Research Articles

Evaluation of the stock enhancement effect of Phascolosoma esculenta on macrobenthic communities using diversity and biotic indices in Yueqing Bay, East China Sea

Stock enhancement activities have many benefits but also negative impacts. The macrobenthic diversity index and the M-AMBI index were adopted to assess the effects of stock enhancement of Phascolosoma esculenta on macrobenthic communities and the local ecosystem in Yueqing Bay. The results revealed that the Shannon–Wiener diversity index (H’) and Margalef richness index (d) increased in October 2022 after stock enhancement, indicating a positive ecological restoration effect. The average M-AMBI in the intertidal zone of Yueqing Bay was 0.59, indicating good benthic ecological quality. Excluding seasonal factors, the M-AMBI in the intertidal zone increased after stock enhancement, indicating that stock enhancement by Phascolosoma esculenta had a certain positive effect on the intertidal ecological environment of Yueqing Bay. The increase in the M-AMBI occurred mainly in the low-tide zone, increased slightly in the mid-tide zone, and remained basically unchanged in the high-tide zone. On the one hand, Phascolosoma esculenta can accumulate heavy metals from the environment and release a large amount of organic matter throughout its lifecycle, promoting nutrient cycling, which plays a positive role in the environment. On the other hand, Phascolosoma esculenta is an economic species; however, the planting of mangroves in the low tide zone causes fishers to fish in the mid- and high-tide zones, so the changes in the M-AMBI values in each tidal zone are related mainly to Phascolosoma esculenta and anthropogenic disturbances.

Assessment of polychaete diversity in selected tropical Islands and estuaries on the Southeast coast of India

Increased anthropogenic pressure on the marine environment leads to severe threats to resident biota, a global concern. The Gulf of Mannar (GoM) and Palk Bay (PB) on the Southeast coast of India are two notable ecological hotspots. However, increased industrialization, tourism, and fishing activities in recent years have contaminated the environment and biota of these two ecologically significant coastal zones. This study aims at the impact of seasonal dynamics on polychaete assemblages in four coastal areas (Kanyakumari, Thoothukudi, Ramanathapuram, and Cuddalore) along the southeast coast with different seasons (post-monsoon, summer, pre-monsoon, and monsoon). In all the collected parameters, salinity is the prime variable influencing the distribution of polychaetes greatly; they link to other environmental parameters. Results revealed that temperature, pH, chlorophyll, and total organic carbon all exhibited a strong positive correlation with salinity; others showed a negative correlation. According to a one-way ANOVA, the Kruskal-Wallis test and Pearson correlation have significant differences at the spatial scale (p<0.05). Overall, the multivariate analysis of PCA and CCA, followed by indices like Shannon diversity index and AMBI and M-AMBI indices results, revealed that spatial heterogeneity of the polychaetes was influenced by salinity, temperature, pH, DO, TN, TP, TOC, and clay (p<0.05). The environmental changes and anthropogenic activities are the reason for the spatial variation in the polychaetes.

The Ecological Role of Ruppia cirrhosa (Petagna) Grande in a Choked Lagoon

We studied the ecological and functional aspects (such as role in sediment characteristics and plant–animal interactions) of a Ruppia cirrhosa (Petagna) Grande meadow during its vegetative season in the choked Valle Campo lagoon, a sub-basin of the wider Valli di Comacchio, on the Northern Adriatic coast. Sampling campaigns were carried out with a roughly fortnightly frequency in 2017 at two sites, one with the Ruppia meadow and one with bare sediment. Sediment parameters analyzed were microphytobenthic chlorophyll-a, protein, carbohydrate, and lipid content, and total organic matter. The macrobenthos was identified at the lowest possible taxonomic level. Chlorophyll a, as a surrogate of microphytobenthos, showed differences between the two sites, probably mainly related to light intensity; thus, it is expected that the absence of seagrass canopy results in the higher production of microphytobenthos. At both sites, proteins were the dominant class of labile compounds, suggesting that detrital organic matter present at both study sites is of high nutritional quality. The high protein/carbohydrate ratio also suggests the presence of non-aged organic matter. We recorded a total of 18 macroinvertebrate taxa. The Ruppia meadow showed a positive influence on macrofauna abundance, diversity, species richness, and composition of trophic groups. Only the infaunal taxa Capitella capitata and Chironomus salinarius exhibited higher abundance at the bare site. The ecological quality status measured by the M-AMBI index was unsatisfactory everywhere. However, the presence of the Ruppia meadow resulted in index values being consistently higher. The role of this minor seagrass has been proved to be of great importance, improving the nutritional quality of the organic matter in the sediments and, above all, providing new habitats and new niches for a number of benthic macrofauna species.

A preliminary study of soft bottom benthic communities in an area affected by intense maritime traffic (Slovenian Sea, Northern Adriatic)

Maritime traffic and port activities pose several environmental and ecological problems in the marine environment. The purpose of this study was to provide baseline data for the future assessment of anthropogenic impacts related with port activities in Slovenian Sea (Northern Adriatic Sea). The macrobenthic communities near the port of Koper, as well as sites offshore were analysed. Results showed that the sites offshore were generally richer and more structured than sites inside the Port area. Those differences were explained partly by depth and sediment grain size. The ecological quality indicated by M-AMBI index resulted Good/High at all the sampling sites. However, the k-dominance curves indicated a disturbance at certain sites, in particular in the port channels. This work highlights the need for consistent monitoring programs to provide baseline data for future studies assessment of anthropogenic impacts.

Seasonal implications of the benthic ecological status assessment in a protected Mediterranean coastal lagoon: Stagno Longu of Posada (Sardinia, Italy)

Understanding how biotic indicators respond to natural variability is essential for the health state evaluation of the benthic ecosystems. This study analysed the composition and structure of the benthic communities in the coastal lagoon Stagno Longu of Posada (Sardinia) to investigate the seasonal response of the biological indicator M-AMBI. Multivariate analysis and biodiversity descriptors showed temporal (winter–summer) and spatial variability (across the three basins of the lagoon).The ecological status (ES) of Stagno Longu was assessed using M-AMBI index: results mainly showed the lagoon to be in “good” and “moderate” status across seasons and basins, while “poor” status was recorded in the North basin during summer.Despite the absence of direct human pressures, sediment organic content (OC) varied seasonally and spatially and M-AMBI revealed winter to summer shifts on the ES of 3 out of 6 sampling stations. Overall, this study reveals negative significative correlation on the variations on M-AMBI with the increase of sediment OC across the studied sites, none the less discrepancies on the ES of certain stations were detected causing over/underestimation.Results suggested that natural seasonal variability is a relevant factor to be considered while performing ES assessments and implementing monitoring programmes in Mediterranean transitional ecosystems when applying indicators such as M-AMBI.

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).

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.

The benthic environmental footprint of aquaculture in the Eastern Mediterranean: Organic vs conventional fish farming

A field experiment was carried out in a fish farm of the Eastern Mediterranean in order to evaluate the benthic environmental footprint of the organic versus the conventional fish farming. The highest values of chl α were recorded at the conventional culture during both studied seasons. The organic matter and organic carbon rates recorded at the conventional culture were significantly higher than those observed at the organic culture in both studied seasons (p < .05). Furthermore, in all cases the quality characteristics of benthic community variables were optimum at the organic culture compared to the conventional one and similar to those of the control. SIMPER analysis showed that the maximum average dissimilarity occurred between organic and conventional culture, while the main contributor species for this dissimilarity was the polychaete Capitella capitata. Multidimensional scaling (MDS) ordination plot indicated clearly a separation of the organic and conventional fish farming during both studied seasons. K-dominance curves revealed a clear difference in elevation, mainly during summer. M-AMBI index showed a poor to moderate environment for conventional culture, while organic one was good to high and similar to the control site (high). The results indicated the lower environmental footprint of the organic fish farming compared to the conventional, demonstrating its potential as an important management tool, which could play a significant ecological role for the sustainability of aquaculture in the Mediterranean region.

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.

Evaluation of macrobenthic community responses to dredging through a multimetric approach: Effective or apparent recovery?

Macrobenthic responses to dredging activities were evaluated in a mesotidal coastal lagoon (Ria Formosa – South Portugal). Four areas (2 dredged and 2 non-dredged) were analysed along different dredging situations (pre-dredging, during dredge 1, during dredge 2 and post-dredging). Beyond the evaluation of sediment descriptors and classical ecological indicators (number of species and abundance), the beta diversity component (partitioned into turnover and nestedness) was used to detect dredging effects on macrobenthic communities, together with a multivariate analysis (both quantitative and qualitative) including the ecological status assessment. Results confirmed the limitations of alpha diversity indicators in detecting dredging effects in naturally stressed systems, given the absence of clear patterns regarding number of species, abundance and equitability among areas and dredging situations. Moreover, post-dredging presented a higher number of species compared to pre-dredging, suggesting a positive disequilibrium induced by these activities. In contrast, partitioned beta diversity analysis revealed higher nestedness values at dredged areas, while turnover clearly prevailed at non-dredged ones. Such results suggest an effective impact of dredging on these communities, namely through the decrease of rarer species after sediment removal. This qualitative analysis, based on presence-absence data (Sorensen dissimilarity), was complemented by multivariate analysis (SIMPER and PERMANOVA) based on quantitative data (Bray-Curtis dissimilarity), highlighting the importance of adopting both approaches to detect dredging impacts on benthic communities. Lower effectiveness was found for M-AMBI index when evaluating benthic Ecological Status, since the apparent absence of organic matter and sediment composition shifts induced by dredging, together with the noticeable high diversity even during dredging situations, strongly limited the analysis. The multimetric approach here proposed can contribute to detect dredging effects on lagoonal benthic communities by disentangling the responses caused by dredging from those resulting from the system natural dynamics.

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.

Analysis of macrobenthic assemblages and ecological health of Yellow River Delta, China, using AMBI & M-AMBI assessment method

Yellow River delta (YRD) is a typical example of a valuable coastal ecosystem that is under increasing anthropogenic threat in China. To understand the current health status of this region, three surveys in 2011 for the abiotic conditions and macrobenthic assemblages were performed. The concentration of trace metals were relatively low in the sediment at all sampling stations representing a good sediment quality. A total of 159 macrobenthic species were identified during the three surveys. ABC curves showed that the macrobenthic fauna at 8 sampling stations suffered disturbances from human activities. M-AMBI index indicates that the benthic ecological quality of YRD is currently still not in a good condition. Five trace metals, water temperature and depth were the main environmental variables affecting the distribution pattern of macrobenthic assemblages. Community succession has occurred over the past 60years, as evidenced by changes of species composition, key species, distribution pattern and range.

Determining Ecological Status of Two Coastal Waters in Western Java using Macrozoobenthic Community: A Comparison between North Part and South Part

The main problem of coastal waters in Indonesia is generally caused by anthropogenic activities that promoting the accumulation of organic matters in sediments. It was well-known that organic matters in sediment might influence the macrozoobenthic communities. AMBI and M-AMBI are two recent developed indices which could be used to evaluate the health of soft bottom macrozoobenthic community and their ecological quality status. This present study was aimed to compare and evaluate the ecological status of macrozoobenthic communities in Tangerang coast (northern part of Java) and Palabuhanratu Bay (southern part of Java) based on AMBI and M-AMBI indices. This study was conducted in April-May 2013 in Tangerang coastal area, and in May 2016 in Palabuhanratu Bay. There are 18 sampling sites in the Tangerang coast, and 30 sampling sites in Palabuhanratu Bay. The results showed that the disturbance level of macrozoobenthos community in Palabuhanratu Bay based on AMBI analysis ranged from undisturbed to slightly disturbed, while in Tangerang coastal waters ranged from undisturbed to moderate disturbed. Ecological quality status based on the M-AMBI ranged from poor to high for both locations. The AMBI and M-AMBI indices showed that benthic environment in Palabuhanratu Bay was ecologically better than that inTangerang coastal waters.

A comparison of the applicability of the Shannon-Wiener index, AMBI and M-AMBI indices for assessing benthic habitat health in the Huanghe (Yellow River) Estuary and adjacent areas

From a dataset of macrobenthos obtained from 18 cruises from 2004 to 2013 in the Huanghe (Yellow River) Estuary and its adjacent areas, the composition and characteristics of macrobenthos were analyzed, and the applicability of the Shannon-Wiener Index (H′), AZTI’s Marine Biotic Index (AMBI) and multivariate AMBI (MAMBI) for assessing benthic habitat quality was compared. The results showed a total of 203 macrobenthos in the study area. The macrobenthos were dominated by polychaetes, followed by mollusks and crustaceans. The macrobenthic ecological groups were dominated by EGI, EGII and EGIII, which respectively accounted for 31.5%, 36.0% and 21.2% of the total. There were significant differences between the evaluation results of the three indices. The ecological quality status (EQS) levels given by the AMBI were greater than those given by the H′ and M-AMBI. The AMBI could not reflect the differences between 11 sites but the H′ and M-AMBI could do. Moreover, the three indices responded well to the variations in salinity (S) and dissolved oxygen (DO) in the waters. The H′ and M-AMBI also responded sensitively to the differences in physical parameters, such as water depth and sediment texture. The correlation between M-AMBI and environmental pressure gradient data was the strongest. The MAMBI could effectively distinguish degraded conditions from undegraded but the H′ and AMBI could not. Therefore, the M-AMBI reflected benthic habitat health well in the study areas. However, the objectivity of evaluation results of M-AMBI needs further verification by physical, chemical and biological methods. The thresholds also need further discussion.

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.

Offshore platforms: Comparison of five benthic indicators for assessing the macrozoobenthic stress levels

Within the European Water Framework Directive, many studies have been conducted to evaluate the sensitivity/robustness of a variety of indices in relation to natural or anthropogenic disturbance events. However, these indices have rarely been applied to verify the impacts of disturbances in offshore environments, though the Marine Strategy Framework Directive recommends their use for assessing benthic community conditions and functionality. The aim of this paper was to determine which biotic indicator performed the best for detecting the impacts of offshore structures on benthic populations in the Adriatic Sea. The impacts of four rigs were investigated six months after their installation, and the H′, AMBI, m-AMBI, BENTIX, and BOPA indices were assessed. Although these five indices delivered some contradictory results because of the differences in their structure and discrepancies in their assignment of species sensitivity, the BENTIX, H′ and BOPA indices appear to evaluate stress levels better than the AMBI and m-AMBI indices, which tend to provide results that are slightly overly optimistic.

Effects of organic enrichment on macrofauna community structure: an experimental approach

The determination of the resilience of benthic assemblages is a capital issue for the off-shore aquaculture industry in its attempts to minimize environmental disturbances. Experimental studies are an important tool for the establishment of thresholds for macrofaunal assemblages inhabiting sandy seabeds. An experiment was conducted with three treatments (Control, 1x and 3x),in which organic load (fish pellets) was added (1x (10 g of fish pellets) and 3x (30 g)). A reduction in abundance of individuals and species richness was found as between the control and organic-enriched treatments. Significant changes in assemblage structure were also found, mainly due to the decrease of the sensitive tanaid Apseudes talpa in organically-enriched treatments. AMBI and M-AMBI indices were calculated and a decrease of ecological status was observed in treatment 3x.

Influence of sampling effort on ecological descriptors and indicators in perturbed and unperturbed conditions: A study case using benthic macroinvertebrates in Mediterranean transitional waters

The effectiveness and accuracy of biomonitoring programs, based on benthic macroinvertebrates, is strictly related to the sampling design and effort, whereas the feasibility depends on the economic sustainability of sample collection and processing methodologies. In the last decade, how to improve the Rapid Bioassessment Protocols (RBPs) maintaining the accuracy of the results has been a topic recurrently debated among researchers. It is well known that the sample unit size (i.e., surface of the sampled area, SUS) and the sieve mesh size (SMS), selected to collect and to retain benthic macroinvertebrates from soft-bottom samples, may affect the evaluation of the aquatic ecosystem ecological status; however, studies analyzing the combined influence of SUS and SMS on assessment tools are lacking, in particular for transitional water ecosystems. Even if the Water Framework Directive (WFD) suggests rapid and cost-effectiveness sampling effort and procedures, the identification of optimal SUS and SMS is a basic step to improve the RBPs and to meet WFD suggestions. Therefore, this research analyses the effects of four soft-bottom sample unit sizes (0.0225m2, 0.0450m2, 0.0675m2, 0.0900m2), and three sieve mesh sizes (4mm2, 1mm2, 0.25mm2) on the selection of benthic macroinvertebrates and, thus, on assessment tools, in a Mediterranean lagoon. A sampling survey was performed in September 2009 at a perturbed and an unperturbed study site in the Lesina lagoon (SE Italian coastline); three replicates were taken for each SUS and SMS using an Ekman–Birge grab (15cm×15cm). The samples were sieved on a column of three sieves, with decreasing mesh size. Benthic macroinvertebrates were sorted, identified, measured, weighted and included in twelve datasets (4 SUS×3 SMS). Sampling effort (SE) was calculated for each SUS and SMS combination as: SE=[SUSm2×(1/SMSmm2)]×100. Four simple community descriptors (numerical density, taxonomic richness, biomass density, individual body-size) and four ecological indicators (AMBI, BENTIX, BITS, M-AMBI) were compared for each combination of SUS and SMS in both study sites. Simple community descriptors and ecological indicators varied significantly between perturbed and unperturbed study site. The results showed that SMS had significant effects on simple community descriptors and ecological indicators, except for BITS index. Conversely, no significant differences were observed for different SUS analyzing simple community descriptors and ecological indicators, except for taxonomic richness and M-AMBI index. The response of the ecological indicators was only slightly affected by the SMS, whereas SUS choice did not influence the ecological status assessment. Anyway, using the larger SMS (4mm2), all ecological indicators showed either the same ecological quality status as the 1mm2 and 0.25mm2 SMS or, in some cases, one class higher, except for the AMBI index.

Benthic biodiversity patterns in Ria de Aveiro, Western Portugal: Environmental-biological relationships

This study characterizes the macrobenthic gradients in Ria de Aveiro, Western Portugal. Ria de Aveiro is the meeting place of a number of river basins, resulting in a transition system of complex geometry, with channels running parallel to the coast line, north and south of the entrance, but also inland, creating an intricate system of navigation channels, islands and intertidal sand and mudflats. This renders unique characteristics to this system within the framework of transitional waters. The study was based on the analysis of samples from 248 sites, covering the full salinity gradient and the entire channel system. A total of 120 taxa in more than 76,350 specimens were identified. The most abundant and frequent taxa were all annelids, namely Alkmaria romijni, Streblospio shrubsolii, Tharyx sp., Tubificoides benedii, Nereis diversicolor, Capitella sp., Pygospio elegans, Polydora ligni and an unidentified oligochaete. The spatial distribution of the fauna was found to be mainly related to hydrodynamics and the salinity gradient, whereas sediment grain-size characteristics were much less important. Shear stress, flux, current velocity, salinity and sediment redox potential were the environmental variables which best related to the biological data. Benthic assemblages succeed from the euhaline pole, at the entrance, to the limnetic poles, located in the inner parts of the channels. In this succession, mean abundance increased from the outward to the inward assemblages but species richness and diversity were higher in intermediate assemblages. These descriptors decrease abruptly in the limnetic areas. Using the M-AMBI index, the ecological quality of Ria de Aveiro revealed moderate, poor and bad status. However, the ecological status spatial trend closely followed the benthic assemblages succession, their species richness and diversity, indicating the need for proper reference conditions and inter-calibration exercises in the transition waters before final assessment and conclusions about the use of such indices may be drawn.

Analysis of macrobenthic assemblages of Lake Illawarra, New South Wales, Australia

1 - A survey of the macrobenthos community was carried out in Lake Illawarra, NSW, Australia, during April and May 2011. 2 - The aim of this study was to understand the current status of the characteristic macrobenthic fauna community, and the temporal changes over the past 30 years, as well as the impacts of anthropogenic activities on the benthic ecosystem. 3- Fifteen stations were selected as representative of three main areas of the lake (the entrance channel, the central basin and the sublittoral fringe), which might be impacted by different kinds of human activities. 4 - A total of 45 macrobenthic species were identified. Mollusca represented the most abundant taxon with 17 species, followed by Crustacea with 16 species. Three species were dominant, i.e., the mollusk Nassarius burchardi, and the polychaeta Lumbrineris sp. and Nephtys australiensis. 5 - The abundance and biomass of the macrobenthos were variable between the three main areas. Based on Bray Curtis similarity of macrobenthos, the 15 sites also divided largely into three groups. 6 - M-AMBI index analysis indicated that eight stations (57.1%) had ‘good’ to ‘high’ ecological status (EcoQ), four stations (28.6%) ‘moderate’ EcoQ, and two stations (14.3%) with ‘poor’ to ‘bad’ EcoQ, which indicates the Lake Illawarra was in reasonably good condition, but evidence of disturbance and impact on benthic communities was obvious at several sites.