Shifts in Estuarine Macroinvertebrate Communities Associated With Water Quality and Climate Change

The present work aims to identify changes in the macroinvertebrate community of the Tagus estuary (Portugal) due to improvements in water quality and to climate change. Data was collected over a period of 16 years (1998–2014) from different sites located along the estuarine gradient. The AZTI Marine Biotic Index (AMBI) was used to assess the ecological quality status based on benthic invertebrate communities and identify possible variations associated with changes in water quality. The overall distribution of each species was examined to detect possible changes associated with climate, based on species’ affinity for more temperate or subtropical climates. Results demonstrate that there was an overall improvement of AMBI scores during the assessment period. The analysis of the geographical distribution of benthic species seems to indicate that there has been an increase of species which prefer subtropical climates in the shallower waters of the estuary, whereas in the deeper estuarine sections the propensity is for species that prefer temperate climates.

Comparison of Four Foraminiferal Biotic Indices Assessing the Environmental Quality of Coastal Mediterranean Soft Bottoms

Coastal environments are exposed to numerous pressures that potentially affect marine soft bottom faunas. Among these pressures, organic matter enrichment is very frequent. Several indices based on living (Rose Bengal-stained) foraminiferal communities have recently been developed to assess the induced impact and determine the environmental quality of these environments. Here, we use an open waters Mediterranean Sea data set to test the benefits and drawbacks of four foraminiferal indices: (1) the effective number of species (exp(H’bc)), (2) the Tolerant Species Index for the Mediterranean (TSI-Med), (3) the Foraminifera AMBI (Foram-AMBI), and (4) the Foram Stress Index (FSI). These indices all intend to measure the response of the foraminiferal communities to organic matter enrichment, and therefore, their results should be very similar. We found that the diversity-based index, exp(H’bc), was not suitable to evaluate the environmental quality of our Mediterranean coastal settings, as it had a non-monotonic relationship with the organic matter enrichment gradient. The three indices based on groups of indicator species (TSI-Med, Foram-AMBI, and FSI) yielded fairly similar results. For Foram-AMBI, using only assigned species to calculate proportions of indicator species partly avoided to misinterpret the results. In TSI-Med, a correction based on sediment grain size is applied to distinguish between natural and anthropogenic organic enrichment. Such a correction could also be added to Foram-AMBI and FSI. The limits between the Ecological Quality Status (EQS) classes used for macrofauna were not adapted for Foram-AMBI. Here, we propose new EQS class limits for the Foram-AMBI as follows: very good: 0 ≤ x < 1.4; good: 1.4 ≤ x < 2.4; moderate: 2.4 ≤ x < 3.4; poor: 3.4 ≤ x < 4.4; bad: 4.4 ≤ x ≤ 6. These limits could evolve in the future as new data become available, especially with a poor and bad environmental quality.

Assessment of Benthic Ecological Quality Status Using Multi-Biotic Indices Based on Macrofaunal Assemblages in a Semi-Enclosed Bay

Semi-enclosed bays have physical and chemical characteristics influenced by both land and sea systems and the quality of the benthic environment is always of great concern. Macrofauna are considered good indicators for evaluating the benthic ecological quality status owing to their biological characteristics. In this study, six biotic indices, namely the Shannon–Wiener diversity index (H′), Abundance-Biomass Comparison (ABC) curve, AZTI’s Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI), BOPA index, and BENTIX index, were used to evaluate the adaptability of different biological indices in the bioassessment of the benthic environment in a semi-enclosed bay. In the annual environmental assessment of the study area, the average values of the six indices (H′, ABC curve, AMBI, M-AMBI, BOPA, and BENTIX) were 4.494, 0.182, 2.433, 0.791, 0.033, and 3.813, respectively; accordingly, H′, M-AMBI, and BOPA met the high standards whereas the other indices met the good standards, indicating that the whole study bay was slightly disturbed and had good ecological quality. From the perspective of spatial variation, the benthic environment in the middle of the bay was better than that in the north; the environmental problems in the northeast were particularly noteworthy. In terms of temporal patterns, the benthic environment in winter and summer was significantly better than that in spring and autumn, with obvious seasonal differences. The present results indicate that the H′ and ABC curve based on benthic abundance and biomass should be avoided for environmental assessment in mariculture areas. AMBI and M-AMBI should be used with caution when the percentage of unassigned species is high, in which case H′ is the appropriate choice. When there are few unassigned species, M-AMBI is more conducive for accurate evaluation of the benthic environment than AMBI and H′.

Can functional units of protozoan periphytons be used to evaluate ecological quality status under harmful algal blooms in marine ecosystems?

Based on biological traits the ecological quality status (EQS) under the pressure of two harmful algal bloom (HAB) species was evaluated using functional units (FUs) of protozoan periphytons. Five treatments with different concentrations of Alexandrium tamarense and Gymnodinium catenatum were designed as100, 102, 103, 104 and 105 cell ml− 1. A total of 21 FUs were identified from 25 test protozoan species. Vagile algivores with large sizes showed a decreasing trend towards high concentrations, while the vagile bacterivores and non-selectives with small sizes were dominating in concentrations (104 cell ml− 1) of both algal species. Ellipse test on pair-wise functional distinctness indices revealed a significant departure of test protozoan samples from an expected pattern when algal concentrations were over 104 cell ml− 1. Thus, it is suggested that FUs of protozoan periphyton assemblages may be used as a useful tool for evaluating the effects of HAB on ecological quality status in marine ecosystems.

Evaluating the Applicability of Phytoplankton Community Indices in Assessing The Ecological Quality Status (EcoQS) of a Coastal Ecosystem (Thane Creek, India): Mono-Metric vs Multi-Metric Approach

The ecological quality status (EcoQS) of Thane Creek which is surrounded by a highly urbanized and industrialized sector of Mumbai was assessed by considering six phytoplankton community indices. Sampling was carried during Premonsoon to compare the efficiency of selected indices (Chl a, abundance, H′, MDI, IPI and MMPI) in the tropical setting. Ecostatus proposed by selected phytoplankton indices assigned a 'moderate-good' status to phytoplankton zone (PZ)-I, 'moderate-poor' to PZ-II while 'bad' to PZ-III. Comparatively, MMPI appeared to be the most efficient water quality index because of its capability in discriminating between 'acceptable' and 'not-acceptable' EcoQS. The gradient of anthropic activities along the creek plays a major role in deciding the EcoQS of Thane Creek. Limitations of all indices in evaluating environmental quality were also discussed in the present study. The investigation could provide a fillip to policymakers who are undertaking coastal water quality improvement initiatives.

Environmental monitoring of the highly polluted Gulf of Bagnoli (Italy) using foraminiferal metabarcoding and morphology-based assessment

The former-industrial site of Bagnoli (Naples, Southern Italy), the second Italian largest steelwork, has been negatively affected by the discharges of heavy metals and hydrocarbons that have markedly altered the water and sediment quality as well as the biota living therein. On the basis of benthic foraminiferal traditional morphology-based approach and eDNA metabarcoding, we evaluate the response of benthic foraminifera to pollution and define the Ecological Quality Status (EcoQS) in Gulf of Bagnoli. Higher concentrations of Pb (up to 322 ppm) and Zn (up to 795 ppm) than Effect Range Median are identified in the area in front of the former industrial site, specifically between the two piers. Indeed, significant differences in terms of alpha and beta diversity have been found between the most polluted area (i.e., in front of the former industrial plant) and the sites in the northern area that can be considered relatively low polluted. The analysis of selected biotic indices (i.e., exp(H’bc), Foram-AMBI, gAMBI) computed for the morphological and metabarcoding datasets strikingly and congruently identify poor to bad EcoQS in the polluted area in front of the former industrial plant, whereas the EcoQS results good to high North to the site. The congruence and complementarity between metabarcoding and morphological data support the application of foraminiferal metabarcoding in routine biomonitoring as a reliable, time- and cost-effective methodology to assess the environmental impacts of heavily polluted marine areas.