Deciphering benthic ecosystem functioning and resilience in a major port and marine protected area via the multi-trait approach.

The preservation of ecosystem functioning of coastal zones, in face of increasing environmental stressors and species extinctions, relies on the functional redundancy and inherent resilience of its inhabitants. To compare the benthic functioning and resilience of a disturbed area with a relatively less impacted area, a study was conducted in Mumbai Port and Malvan Marine Protected Area (MPA), which exhibited contrasting characteristics. The hypothesis posited that the anthropogenically influenced Mumbai port would exhibit lower functional parameters and resilience compared to Malvan. Overall, the MPA presented higher species richness and functional diversity with a greater presence of sensitive species, while Mumbai was dominated by the presence of opportunistic species, as anticipated. However, our findings demonstrated that despite varied trends in species diversity metrics, in both the coastal areas, the resemblance in benthic functioning was high due to similarity in dominant trait profiles. Surprisingly, Functional Richness was higher at Mumbai, while Functional Evenness, Divergence and Dispersion were comparable at both sites. The resilience, as quantified by Functional Redundancy, was also comparable at both areas attributable to the presence of clusters of species with similar traits and a low occurrence of rare traits. The combination of traits observed in both areas was influenced by the extant environmental conditions, as revealed by RLQ analyses. This study underscores the valuable insights provided by the application of Biological Trait Analysis (BTA) tool in deciphering the relationship between species diversity and ecosystem functioning, as well as the resilience capabilities of ecosystems subjected to varying levels of perturbation. Moreover, the incorporation of functional diversity indices yielded valuable inferences regarding ecosystems resilience, which can aid future ecosystem management strategies.

Tracing the impact and recovery trajectory of oil spill affected tropical rocky intertidal macrobenthic communities using the BOPA index.

A yearlong study was conducted to assess the impact of an oil spill on macrobenthos of rocky intertidal zone of Uran, India and its recovery processes, by comparing impacted site with a reference. Immediate acute effects observed were elevated sediment hydrocarbons, absence of macroalgae and amphipods, mass mortality of macrofauna and dominance of the opportunistic nereid, Namalycastis senegalensis. As the hydrocarbons reduced at the impacted site by ~50 % within three months, gradual re-appearance of macroalgae and re-colonization of amphipods (51.4 %) and sensitive polychaetes (7 %) indicated that the recovery was well underway. The amphipod, Allomelita pellucida proved to be a potential indicator of oil contamination. BOPA correlated with sediment hydrocarbons and performed effectively as the extant macrobenthic communities had sufficient representation of Polychaeta and Amphipoda. Notwithstanding the distinct initial impacts of the oil spill, comparable macrobenthic assemblages comprised of sensitive species at both sites after a year confirmed complete recovery.

Ecological quality status assessment of tropical estuaries with benthic indices using differently derived reference conditions.

Setting appropriate reference conditions (RCs) is critical for classifying the Ecological Quality Status (EcoQS) which is extremely challenging, considering the present-day estuaries. The EcoQS of three tropical estuaries was assessed by applying five different RCs to identify the best applicable method for the area. The AZTI's indices (AMBI and M-AMBI) categorised areas with sharper pollution gradient with ease, while classification of moderate-low polluted areas was ambiguous. Indices responded to chemical stressors more clearly in the impacted estuary compared to the less polluted estuaries. Ecological status assigned by the default RC (lowest AMBI and highest diversity and richness values) were more accurate than those obtained on application of other four types of RCs, owing to various estuarine constraints that are discussed herewith. Thus, prior to application, caution should be exercised while setting area-specific RCs. The inclusion of combination of AZTI's indices with professional judgment for successful appraisal of ecosystem is recommended.

Factors structuring spatio-temporal dynamics of macrobenthic communities of three differently modified tropical estuaries.

Tropical estuaries of industrialized northwest coast of India, subject to seasonal and multifarious anthropogenic interventions, are poorly studied. Three estuaries, Ulhas, Amba and Savitri were investigated seasonally to identify the principal factors among natural and anthropic stressors that shaped spatio-temporal macrobenthic patterns. The macrobenthic community structure and chemical parameters differed significantly between estuaries, zones and seasons. Multivariate dispersions were significant between the estuaries whereas for the zones and seasons, significant variability was nonexistent. Multivariate regression analysis indicated that both natural and anthropogenic drivers influenced the spatio-temporal variability of macrobenthos of Ulhas and Amba. In Savitri, no anthropogenic factor was significantly influential. Salinity explained a greater proportion of the variability of macrobenthic structure than other factors in all estuaries. The pollution tolerant species responded largely to salinity changes and were observed to inhabit specific salinity zones. Thus, the spatio-temporal patterns of the estuarine macrobenthos were primarily dictated by the salinity.

Ecological quality status evaluation of a monsoonal tropical estuary using benthic indices: comparison via a seasonal approach.

The use of biotic indices has garnered attention during the last decade due to its extensive application in evaluating ecological quality status (EcoQS) of marine waters and estuaries. Three seasonal surveys were conducted in the Kundalika estuary, India to evaluate the ecostatus using five benthic indices and comparing their effectiveness considering the estuarine salinity gradient and seasonality. All indices gave divergent results displaying a wide range of classes (good to bad) across salinity zones and seasons. Comparatively, M-AMBI discriminated the EcoQS suitably than other indices. Hence, a seasonally averaged approach for M-AMBI was proposed to obtain a final mean EcoQS which assigned moderate status to the euhaline and poly-mesohaline zones and poor status to the oligohaline zone. Considering the high degree of spatial heterogeneity and seasonality in the estuary, the monsoon data was found to lower the EcoQS due to natural stress in some cases; the exclusion of the monsoon season resulted in a more valid ecostatus. Therefore, this approach which combines information from the non-monsoon seasons stands out in providing a useful basis for ecological management by scrutinizing responses of macrobenthos. Also, we suggest salinity zone-wise evaluation for more effective classification chiefly in tropical monsoonal estuaries. An effort to establish a final EcoQS was performed; however, future in-depth studies are necessary to ascertain the reliability of the successful biotic index (M-AMBI) in estuaries with different stressors.

Comparative efficacy of benthic biotic indices in assessing the Ecological Quality Status (EcoQS) of the stressed Ulhas estuary, India.

Ecostatus of Ulhas estuary, one of the most polluted estuaries along the industrialized and urbanized northwest coast of India, was evaluated by six widely accepted benthic indices viz. H'(log2), AMBI, M-AMBI, BENTIX, BOPA and BO2A to test their efficiency in a tropical setting. The mesohaline zone, which presented eutrophic conditions, was classified as 'bad' by all indices due to the azoic status. Despite significant correlations obtained between indices, there were discrepancies in the accurate level of EcoQS assigned to each station. AMBI was observed to be most efficient in indicating a clear spatial variability from a 'poor' to 'bad' ecological quality status in the middle and upstream zones to an improved status in the downstream region. Limitations of all indices are discussed in light of their suitability for assessing the estuarine environmental condition. The present results could provide a fillip to environmental improvement initiatives currently being undertaken in the estuary.

Polychaete Community of a Marine Protected Area along the West Coast of India-Prior and Post the Tropical Cyclone, Phyan.

Tropical cyclones are extreme random meteorological events that can have profound implications to coastal biodiversities. Given that the frequency, intensity and duration of these events are poised to increase due to the global climate change, understanding the ecological impacts of such erratic occurrences becomes imperative to devise better management strategies. The eventful passage of the tropical cyclone, Phyan, along the northwestern coast of India in November 2009, coupled with the availability of historical data presented a rare opportunity to elucidate the consequences on the polychaete assemblages of the Malvan Marine Sanctuary and their subsequent recovery. This was achieved by comparison of the pre- and post-Phyan seasonal data from four different sites in and around the Sanctuary. MDS analyses and polychaete community parameters suggested conspicuous cyclone related effects on the polychaete community characteristics in the three outer stations off Malvan, whereas the relatively protected bay station remained more or less unscathed. Impacts, attributable to the cyclone apart from seasonal variations, included changes in polychaete composition, reductions in total polychaete density, species diversity, evenness and functional groups. Dominance of the opportunistic polychaete, Paraprionospiopatiens was all pervasive just after Phyan, resulting in poor diversity and evenness values. In the outer stations, diverse feeding modes present prior to the cyclone were replaced by microphagous feeders post the disturbance. However, the study also observed complete recovery as substantiated by the improvement inpolychaete density, diversity indices and re-instatement of multiple feeding guilds in affected areas. This resilience of the coastal waters off Malvan is attributed to its marine protected status, implying that reduced human interference aided rapid revival of damaged ecosystems.