How restoration engineering measures can enhance the ecological value of intertidal flats

Bohai Bay, a semi-enclosed bay in northern China, is an important spawning and nursery ground for marine organisms but has experienced long-term anthropogenic pressures associated with land-based pollution, coastal engineering, and aquaculture activities. Assessing the ecological status of benthic habitats is therefore essential for evaluating the effectiveness of recent management and restoration measures. Based on summer surveys conducted from 2019 to 2023, benthic macrofauna and environmental data were used to evaluate benthic ecological quality in Bohai Bay using three commonly applied indices: the Shannon-Wiener index (H’), AZTI’s Marine Biotic Index (AMBI), and multivariate AMBI (M-AMBI). The three indices showed generally consistent spatial patterns and interannual trends, although differences in sensitivity were observed. H’ and M-AMBI exhibited clearer spatial gradients and higher concordance with habitat conditions, whereas AMBI produced more clustered classifications. Overall, benthic ecological quality in Bohai Bay displayed a significant improving trend during the study period. The proportion of stations classified as slightly disturbed or undisturbed increased from 81% in 2019 to 96% in 2023, while stations in good or high ecological status increased from 56% to 76%. Spatial heterogeneity remained evident, with stations showing moderate disturbance or poor status mainly associated with localized human activities such as aquaculture, anchorage, and marine engineering. Correlation analysis and redundancy analysis further indicated that benthic communities were jointly influenced by water-column and sediment conditions. Active phosphate in the water column was closely associated with broader regional gradients, whereas sediment sulfide played a key role in shaping local benthic ecological quality and community composition. These results indicate that pollution reduction and coastal management efforts have contributed to measurable improvements in benthic ecological quality in Bohai Bay, while localized human pressures continue to influence benthic habitats, and this study provides a multi-index and multivariate framework for assessing benthic ecosystem responses to human activities that supports adaptive management of Bohai Bay and other semi-enclosed coastal systems.

Benthic macrofaunal communities in the upper Narragansett Bay, Rhode Island have been sampled annually since 2000 as part of the Narragansett Bay Benthic Study (NBBS). This work explored the natural and anthropogenic drivers underlying spatial and temporal variability in benthic community structure. Spatial variability in the structure of Narragansett Bay's benthic macrofaunal communities was related to the degree of exposure to anthropogenic stress. Results suggested a progression in the structure of benthic assemblages from early successional stages in the areas of Mt. Hope Bay and Conimicut Point, to an intermediate stage at the mouth of Greenwich Bay and culminating with late stage succession north of Jamestown. This north-south successional gradient mirrors expectations based on historic models of faunal succession that describe predictable changes in the structure of benthic assemblages with spatial or temporal distance from a disturbance. In order to test the hypothesis that temporal variability in water column production affected the structure of the bay's benthic communities, methods for estimating inter-annual differences in the phytoplankton production during the winter-spring (December-May) period prior to each benthic sampling event were developed. Inconsistencies in the response of faunal abundance to changes in pelagic production, when compared to historic models describing benthic community response to organic enrichment, suggested that other factors were influencing temporal variability within these assemblages. Inter-annual differences in communities of adult macrofauna were best explained by measures of epibenthic predation and winter-spring surface water temperature and a model containing these variables along with station location was able to capture the most salient patterns of variability in benthic community structure. Epibenthic predation pressure also explained a significant portion of the temporal variability in the composition and relative abundance of juvenile macrofaunal communities; however evidence suggested the importance of additional factors not included in the present analysis. The specific pattern of inter-annual variability in benthic community structure differed among sampling locations and depended on the successional status of the assemblage. Correlations were also identified between the North Atlantic Oscillation (NAO) Index lagged by one year and the abundance and diversity of communities in the late stages of faunal succession.

Simple SummaryEstuaries are among the world’s most productive ecosystems, but due to their location between land and open sea, they are affected by many anthropogenic pressures, including the consequences of climate change. A rising sea level is one major consequence, which will affect both humans and ecosystems, especially in estuaries with extensive intertidal habitats. There is, however, a lack of knowledge regarding the ecological implications of losing intertidal habitats. Therefore, we investigated how seafloor macrofauna communities and their contribution to ecosystem functioning may change due to rising sea levels. Based on a spatially extensive dataset on macrofauna and environmental variables, we identified three main community groups representing intertidal, shallow subtidal, and deep subtidal habitats. Functional trait analysis indicated low functional redundancy for a key intertidal suspension-feeding bivalve (Austrovenus stutchburyi) and the lack of a shallow subtidal functional replacement should intertidal habitats become inundated (i.e., become shallow subtidal habitats). These findings thus strongly suggest that sea level rise and the associated environmental changes will modify the seafloor macrofauna communities in estuaries, and subsequently, the ecosystem functions that they influence will be altered.Estuaries are among the world’s most productive ecosystems, but due to their geographic location, they are at the forefront of anthropogenic pressures. Sea level rise (SLR) is one major consequence of climate change that poses a threat to estuaries with extensive intertidal habitats. The ecological implications of intertidal habitat loss have been largely overlooked despite their likely significance. We aimed to address this knowledge gap by investigating how benthic macroinvertebrate communities and their contributions to ecosystem function are likely to respond to SLR. Based on a spatially extensive dataset (119 sites) from a large coastal lagoon, depth, sediment chlorophyll concentrations, mud content, and average current speed were identified as the main drivers of community compositional turnover. Shifts in benthic community structure and associated functional implications were then evaluated using depth as a proxy for SLR. Three main macrofaunal groups representing intertidal, shallow subtidal, and deep subtidal habitats were identified. Functional trait analysis indicated low functional redundancy for a key intertidal suspension-feeding bivalve (Austrovenus stutchburyi) and the lack of a shallow subtidal functional replacement should intertidal habitats become inundated. These findings strongly suggest SLR and the associated environmental changes will alter estuarine macroinvertebrate communities, with implications for future ecosystem function and resilience.

Reduced herbivory and enhanced nutrient concentrations have both been suggested as probable mechanisms driving phase shifts from coral to algal dominance on tropical reefs. While there is considerable information regarding the effects of herbivores on reefs, there is little experimental evidence of nutrient effects or the interactive effects of both of these factors. This study experimentally tested the role of these factors on benthic community structure on a coral-dominated reef in Hawaii. A randomized factorial block design was used to simultaneously investigate the effects of nutrient enrichment and herbivore exclusion on the development of benthic algal communities on artificial surfaces over a 6-month time period. Total algal biomass was greatest on settlement surfaces exposed to both nutrient enrichment and herbivore exclusion simultaneously. Fleshy algal biomass was greatest on surfaces removed from grazing whereas calcareous biomass was greatest on surfaces exposed to nutrient enrichment. Control surfaces exhibited consistently less total, fleshy and calcareous algal biomass than that on any of the experimental surfaces. Microinvertebrates were most abundant on surfaces within herbivore exclusion treatments but increased in number on all settlement surfaces over time. Sediment accumulation was positively correlated with fleshy algal biomass and was most abundant on surfaces within herbivore exclusion treatments; there was no pattern in sediment accumulation over time. This research demonstrates that on short time scales (less than 6 months), nutrient enrichment and herbivore exclusion can independently and interactively support shifts in benthic algal community structure on a Hawaiian reef.

Biodiversity and ecological functioning of mudflat macrofauna in the Anthropocene

Variability in benthic invertebrate community structure near warm water effluents of a power plant in the southern Caspian Sea

The effect of sewage and natural seasonal disturbances on benthic macrofaunal communities in Fitzroy Bay, Wellington, New Zealand

Species abundance data for benthic communities, collected during 1971–1988 off Northumberland on the north-east coast of England (western North Sea) and the Skagerrak (eastern North Sea), and pelagic data collected in corresponding areas during 1958–1988 by the Continuous Plankton Recorder (CPR) survey have been subjected tomulti-dimensional scaling ordination. Changes in community structure at the two benthic stations show a high degree of similarity, characterised by a transition in the late 70s. Similarly, there is a less marked transition between the 70s and 80s in pelagic community structure from the eastern North Sea but pelagic data from the western North Sea shows no discernible patterns. Benthic community biomass data, available only for the Skagerrak station, enabled abundance/biomass comparison curves to be constructed which demonstrated a change from un-disturbed communities in the early and mid 70s to moderately disturbed communities in the late 70s and 80s. North Sea macrofaunal abundance, and, in the Skagerrak, macrofaunal biomass appear to co-vary with phytoplankton colour and total zooplankton abundance, although there are insufficient data for statistical testing. A number of factors including eutrophication and/or pollution may be responsible for these changes in community structure.

Coastal ecosystems face increasing anthropogenic pressures worldwide and their management requires a solid assessment and understanding of the cumulative impacts from human activities. This study evaluates the spatial variation of benthic macrofaunal communities, sediments, and heavy metals in the sub-Arctic coastal ecosystems around Sept-Îles (Québec, Canada)—a major port area in the Gulf of St. Lawrence. Physical sediment properties varied in the studied area, with a general sandy-silty profile except for specific locations in Baie des Sept Îles where higher organic matter and heavy metal concentrations were detected. Macrofaunal assemblages were evaluated for two taxa size classes (organisms > 0.5 mm and > 1 mm) and linked to habitat parameters using regression models. Communities of smaller organisms showed signs of perturbation for one assemblage close to industrial activities at Baie des Sept Îles, with an increased number of tolerant and opportunistic species, contrasting to neighboring regions whose compositions were similar to other ecosystems in the Gulf of St. Lawrence. This study enhances the understanding of sub-Arctic benthic communities and will contribute to monitoring programs for industrial harbor ecosystems.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 581:57-70 (2017) - DOI: https://doi.org/10.3354/meps12261 The effects of intertidal oyster reef habitat characteristics on faunal utilization Marc H. Hanke1,2,*, Martin H. Posey1, Troy D. Alphin1 1Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC 28403, USA 2Present address: Honors College, University of Houston, 212 MD Anderson Library, 4333 University Dr., Houston, TX 77204-2001, USA *Corresponding author: marc.h.hanke@gmail.com ABSTRACT: The presence, abundance, and distribution of organisms within a landscape are highly dependent on the composition, quality, and configuration of habitat patches. Intertidal oyster Crassostrea virginica reefs provide a structured habitat for many organisms; however, declining oyster populations have induced reef fragmentation and loss. Over 2 years (2011-2012), we evaluated naturally occurring fringing and patch intertidal oyster reefs in southeastern North Carolina, USA, to determine how varied reef type, size, and distance from edge to interior influenced the associated benthic macrofauna and mobile nekton. In addition, the effects of size and edge vs. interior were examined on constructed intertidal reefs at 2 different locations. On the natural reefs, species richness of benthic macrofauna and mobile nekton were significantly increased on fringing reefs. Benthic macrofauna richness significantly decreased on large natural reefs, whereas mobile nekton richness significantly increased off of large reefs. Further, associated benthic macrofauna richness significantly decreased along the reef edge, whereas mobile nekton diversity increased along the reef/open bottom interface. Species richness and densities for benthic macrofauna increased with created reef size, while there was greater species richness and diversity and dissimilar communities for mobile nekton along constructed reef edges. Habitat specificity may influence utilization for mobile nekton, as resident organisms with limited vagility had a stronger response to habitat characteristics. Thus, utilization of intertidal oyster reefs can be highly structured by habitat characteristics on many scales, and should be considered when examining species interactions, ecosystem management, and future restoration efforts. KEY WORDS: Habitat characteristics · Habitat heterogeneity · Patch size · Edge effects · Mobile nekton · Benthic macrofauna · Habitat fragmentation · Habitat restoration · Oyster reefs · Crassostrea virginica Full text in pdf format PreviousNextCite this article as: Hanke MH, Posey MH, Alphin TD (2017) The effects of intertidal oyster reef habitat characteristics on faunal utilization. Mar Ecol Prog Ser 581:57-70. https://doi.org/10.3354/meps12261 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 581. Online publication date: October 13, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Microbial biogeography and its controlling mechanisms are central themes in microbial ecology. However, we still lack a comprehensive understanding of how habitats and lifestyles affect microbial biogeography across complex environmental gradients. In this study, we investigated the planktonic (including free‐living [FL] and particle‐associated [PA] lifestyles) and benthic prokaryotic communities along a river–estuary–sea continuum of the Changjiang River to explore their distinct spatial dynamics. We observed greater community variability across spatial distances than between habitat and lifestyle types. Spatial variations were evident in FL, PA, and benthic communities, with the highest turnover rates observed in benthic communities, followed by PA, and the lowest turnover rates observed in FL. The replacement effect dominated PA and benthic community variations, whereas the richness effect was more significant in FL communities. Microbial assembly was primarily governed by homogeneous selection and dispersal limitation regardless of habitats/lifestyles, with their ratios decreasing as the spatial distance increased, particularly in the FL fraction. Dispersal limitation had a stronger effect on benthic communities compared to planktonic communities. While heterogeneous selection generally played a minor role, its influence became more pronounced over larger spatial distances and with increasing salinity differences. Finally, we showed that abiotic and biotic factors individually exerted a greater influence on PA communities, whereas their interactions had a stronger effect on FL communities. Our results revealed complex spatial dynamics and assembly mechanisms among microorganisms across different habitats and lifestyles, providing insights into the spatial scaling of community assembly across complex environmental gradients.

Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the ‘grazing halos’ of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways.

The managed realignment project Rammegors aims at re-establishing estuarine nature in a formerly freshwater wetland. For this purpose, a tidal inlet was constructed in the Krabbekreekdam to generate a reduced tidal influence that should allow the development of salt marsh area, tidal flat area and low energetic shallow sub-tidal area. A central question of the Rammegors tidal restoration project is how the flora and fauna will develop in the area. To understand the biotic and abiotic processes related to the tidal restoration in Rammegors, a monitoring programme is being executed by the Centre of Expertise Delta Technology. The monitoring focuses on the main biotic and abiotic developments in the area. This report only focuses on the early colonization of macrobenthic invertebrates in Rammegors. Benthic macrofauna and sediment sampling took place in spring and autumn 2017 and 2018 at twenty-four stations along 5 transects with varying distances from the inlet. A fast colonization of the benthic macrofauna was observed in Rammegors. Twenty-two taxa were observed in the area in spring 2017. The communities significantly differed between spring and autumn 2017. In spring densities reached high values, especially for the brackish mud shrimp Manocorophium insidiosum and mosquito larvae Chironomidae. In autumn these brackish species almost disappeared from the area. Their presence in autumn 2017 and spring 2018, even in low numbers, as well as the observation of the brackish cockle Cerastoderma glaucum indicate that a year after the tidal restoration, parts of Rammegors are still under influence of brackish water. In 2018 these species declined, indicating the transition to a marine environment. A significant relation was found between elevation and the benthic macrofauna. Total density, biomass and species richness showed a significant relation along the elevation gradient with an optimum around +0.4m NAP and lower values at both lower and higher elevations. Total density significant increases with an increase in chlorophyll-a, silt content and organic matter. A significant decrease in total density and species richness was observed with increasing bulk density, indicating that more compact sediments contain less species in lower abundances. Total density, biomass and species richness increased with increasing distance from the inlet. After two years, it is unknown if the community within the Rammegors area reached stability or develops at a slow pace. Future monitoring and a comparison to a community found in a comparable natural habitat is needed to study this.

Benthic community response to habitat variation: A case of study from a natural protected area, the Celestun coastal lagoon

Benthic invertebrate community composition was surveyed across the salinity gradient of the Pensacola Bay Estuary in Florida during summer 2016. Macrofauna densities ranged from 1000 to 9300 individuals m-2 , with highest densities occurring at the upper estuary and the lowest in the mid- and lower estuary. Taxonomic richness and Shannon diversity were lowest in the upper estuary and increased along the salinity gradient. Small-bodied, near-surface infaunal polychaete species (e.g., Mediomastus ambiseta and Paraprionospio alata) dominated the macrofaunal community in fine sediment areas. We calculated the Gulf of Mexico Benthic Index of Biological Integrity for each site and compared the index scores with those from Environmental Monitoring and Assessment Program - Estuaries, an earlier benthic assessment model. Condition evaluations by the different models did not match across all sites in this study; however, scores consistently indicated that most sites were at or near degraded levels, implying that Pensacola Bay represents a marginal habitat for a "healthy" benthic macrofauna community. This study provided new information about the benthic communities and sediments in the Pensacola Bay estuary. Integr Environ Assess Manag 2020;16:245-256. Published 2019. This article is a US Government work and is in the public domain in the USA.