Benthos Research Articles

Ecosystem engineers on tropical reefs in transition: giant barrel sponges in the Anthropocene.

Tropical coral reef ecosystems are changing rapidly to an alternative state in which sponges are the dominant living habitat, with giant barrel sponges (GBSs, Xestospongia spp.) representing the largest biomass. Unlike other benthic reef organisms, GBSs are ecosystem engineers that pump large volumes of seawater, disrupting the benthic boundary layer and directing flow away from the reef surface and into the water column. The morphology and size of GBSs have made them particularly good experimental subjects to study the hydraulics of sponge pumping and the transformation that occurs as seawater is processed by the sponge holobiont (sponge cells and microbial symbionts). This Review is part of a series marking the 100th birthday of The Company of Biologists, which was founded by marine biologist George Parker Bidder III, who primarily worked on sponges. The Review provides an integrative assessment of research on GBSs with comparisons with what is known about other marine sponges. Recent discoveries suggest that ancient lineages of morphologically indistinguishable GBSs are responding to environmental changes over sub-decadal time periods to rapidly populate reefs stripped of coral cover by climate change. If GBSs remain robust to rising seawater temperatures, they will become the greatest source of habitat complexity on reefs of the future, so knowledge of their biology and physiology will be important to our understanding of these ecosystems.

Keanekaragaman Bivalvia di Kawasan Ekosistem Mangrove Desa Jeruju Besar Kalimantan Barat

Bivalves are benthic organisms from the phyllum Mollusca phylum commonly found in mangrove ecosystems, particularly in areas with muddy or sandy substrates. These organisms play an essential role in maintaining ecosystem balance and serve as environmental bioindicators. This study aims to determine the composition, community structure, and environmental parameters that influence bivalve life in the mangrove ecosystem of Jeruju Besar Village, Sungai Kakap District, West Kalimantan. The research was conducted in December 2024 using a systematic method to determine sampling stationss, with a total of 3 stations. Each station has 3 subplots with a size of 1x1 m2 following the transect line which is placed parallel to a distance of 10m. Bivalve diversity in the mangrove ecosystem area of Jeruju Besar Village consists of 2 species, namely, Geloina expansa and Pharella acutidens. Density Station 1 has a density range (0-0.45 ind/m2), station 2 (0-2.28 ind/ m2), station 3 (0-1.64 ind/ m2). The diversity index (H') of bivalves ranged from (0.451-undefined), uniformity index (E') (0.693-undefined), and dominance index (C) (0.722- 1).

Benthic Macroinvertebrates as Bioindicators of Stream Health Within the Central African Copperbelt

Globally, stream ecosystem health in mining regions, including the Central African Copperbelt (CACB), is threatened by increased aquatic metal pollution. Stream biomonitoring and bioassessment offers an eco-friendly nature-based approach to determine the aquatic ecological conditions and inform management interventions in mining landscapes. This study conducted monthly between May 2022 and April 2023, explored the taxonomic and functional responses of macroinvertebrates as bioindicators of the ecological condition of four streams in the north-western Zambian Copperbelt of the CACB. 252 sediment samples were collected and analysed for metals. 144 macroinvertebrate samples were collected to determine their taxonomic and functional traits. ANOVA (analysis-of-variance), SIMPER (similarity-percentage), ANOSIM (analysis-of-similarities), CCA (canonical correspondence analysis) and multidimensional biotic index analyses were conducted to correlate environmental and biotic variables. Metal concentrations (mg/kg) in sediments followed the order As (5.27) < Pb (5.75) < Zn (44.6) < Ni (89.3) < Cu (187.5). From ANOVA, the macroinvertebrate community was significantly dominated by Insecta families, mostly Diptera (23.3%) and Coleoptera (16.7%). Trophically, predators significantly dominated in the order Odonata (34.7%) > Hemiptera (31.8%) > Diptera (18.9%). SIMPER depicted a strong influence of Cu, EC, velocity, sediment texture and organic matter on macroinvertebrate diversity and spatial distribution. ANOSIM indicated the highest community dissimilarity at the most impacted stream (KYABR). Habitat assessment metrics, including ZISS-1, ASPT, and EPT/Chironomidae ratio, registered a “good ecological status” with the presence of pollution-sensitive taxa (Helodidae and Perlidae), in concordance with environmental variables, confirming the suitability of macroinvertebrates as proxy bioindicators of stream health in mining landscapes. The study confirms the potential of macroinvertebrates, as potential bioindicators of stream health in mining landscapes. Their diversity and distribution is strongly influenced by Cu, EC, velocity, and sediment characteristics while habitat assessment metrics indicate a "good ecological status" despite moderate metal contamination.

Connecting the dots: evidence of interactions between wild Atlantic cod Gadus morhua, the benthic environment and salmon farm discharges

Rapid expansion in coastal salmon farming has coincided with declines in coastal Atlantic cod Gadus morhua populations in Norway, raising suspicions over a causal relationship. One established effects pathway concerns the discharge of exogenous waste feed; however, food-web-related pathways remain poorly understood. Here we present a study conducted in 3 neighbouring fjords that are also important cod spawning areas, one of which has several active salmon farms. The study combines spatially explicit information on benthic ecology, cod stomach contents (via eDNA), dietary groups (via fatty acid profiling) and cod source-stock and demographics. Results confirmed that in addition to an anticipated fish diet, wild cod fed on a diverse array of benthic invertebrates, including shrimps, echinoderms, crabs, benthic worms and other infauna. Cod diets differed strongly with proximity to fish farms. Most (69%) cod caught adjacent to a farm had fatty acid trophic markers in their stomachs and/or livers consistent with a salmon pellet diet, and their stomachs contained benthic fauna that proliferate with organic enrichment. This trend was very localised, indicating a degree of residency and feeding specialisation or adaptability. When feeding off the bottom, cod are also likely to ingest contaminated sediments, which can (1) be toxic to marine life, (2) have a strongly altered microbiome and (3) contain known fish pathogens. We conclude that cod are influenced by farm-induced changes to food-web pathways, both in terms of the type and availability of suitable prey species and the composition of their tissues.

Restoration and stabilization of benthic communities in Lake Shihwa: Effects of a tidal power plant.

Restoration and stabilization of benthic communities in Lake Shihwa: Effects of a tidal power plant.

Crown-of-thorns starfish promote additional fine-grained habitat fragmentation in a coral reef ecosystem

ContextSpecies that provide habitat for other organisms are critical for land- and seascape structure. Since coral patch interiors offer different habitats and perform a functionally different role from edges, loss and fragmentation of corals can negatively impact biodiversity. Although processes leading to coral loss have been well documented, their impacts on habitat configuration (arrangement) are poorly documented and understood.ObjectivesWe asked (1) whether Crown-of-thorns starfish (CoTS) forage preferentially on coral edges; and (2) whether they promote fragmentation by increasing the amount of edge habitat more than might be expected relative to random coral loss.MethodsWe used two different years (2012 and 2014, pre- and post-CoTS irruption) of classified photographic imagery from 10 × 10 m transects across 17 different coral reefs in Kimbe Bay, Papua New Guinea.ResultsComparisons to standard neutral models at a grain of 15 cm showed that CoTS do not forage preferentially within or on the edges of coral patches. The fine-grained structure of coral patches in the seascape was substantially more fragmented post-CoTS, particularly at intermediate levels of coral cover. Coral cover declined by a relatively high mean of nearly 5% across all sites, with considerable variance in benthic habitat change between reefs.ConclusionsCoTS are not preferential edge foragers at this scale of analysis. More broadly, our analysis shows how methods developed in terrestrial systems can offer insights into changes in seascape structure and provides useful detail for further research on the ecological impacts of CoTS on benthic fauna.

Spatial Distribution and Diversity of Benthic Macrofauna in Coastal Waters of the Jabal Ali Marine Sanctuary (JAMS), Dubai

The present study aimed to characterize the benthic macroinvertebrate community of the Jabal Ali Marine Sanctuary (JAMS), the sole marine protected area in the Emirate of Dubai, during the summer and winter seasons of 2017. Limited research on the biological quality of the JAMS prompted this investigation, which involved 10 sampling stations to assess macroinvertebrate diversity and community composition in relation to abiotic factors such as sediment granulometry, trace metals, salinity, and temperature. Collected sediment samples were analyzed for macroinfauna, and their abundance was measured, revealing an average abundance of 2150 ind/m2 in summer and 2132 ind/m2 in winter without a significant difference between both seasons. Univariate indices, including the Margalef diversity index and Pielou evenness index, indicate a range of diversity values across sampling sites. Community composition was assessed through SIMPROF and Bray–Curtis similarity clustering, further elucidating the relationship between community structures and environmental gradients. The dominant macroinvertebrate species varied across seasons and stations, providing insights into seasonal variations in community dynamics. These findings contribute to the understanding of benthic community structures and biodiversity in the JAMS and serve as a baseline for future monitoring and management efforts aimed at preserving the ecological integrity of this important marine sanctuary.

Legacy effects of four decades of insecticide applications on contemporary riverine benthic macroinvertebrates.

Legacy effects of four decades of insecticide applications on contemporary riverine benthic macroinvertebrates.

Comparative Analysis of Functional Diversity and Ecosystem Health in Organic and Conventional Rice Paddies: A Trait‐Based Assessment of Benthic Macroinvertebrate Communities

ABSTRACTThis study investigated the functional diversity of benthic macroinvertebrate communities in organic paddy and conventional paddy fields using biological trait analysis and assessed ecosystem health through the Korea Wetland Benthic Macroinvertebrate Index (KWBMI). Field surveys were conducted in Yangpyeong‐gun, Korea, from June to July 2022, collecting benthic macroinvertebrate samples and environmental data. A total of 76 species, 17 orders, and 6797 individuals were identified, with biological traits analyzed among four categories: feeding habits, living types, food types, and voltinism. Community indices showed distinct differences between OP and CP. The dominance index was higher in OP, whereas CP had greater species diversity and evenness. However, functional diversity indices (FRic, FEve, FDiv, and FDis) were similar between the two fields. Despite this, OP exhibited greater taxonomic diversity within functional groups, whereas CP, despite its higher species diversity, contained functionally similar species. KWBMI scores were 84.4 for OP (Grade A: “very good”) and 75.4 for CP (Grade B: “good”), suggesting the potential benefits of organic farming for ecosystem health. Although functional diversity indices remained similar, differences in taxonomic composition and trait distributions indicate that organic farming may promote taxonomic diversity within functional groups, contributing to ecological stability.

Understanding sediment nutrient cycling in a hypersaline coastal lagoon using hydrogel-based passive sampling techniques.

The Coorong, South Australia, is a Ramsar-listed hypersaline coastal lagoon system of significant ecological and cultural importance. Despite facing environmental challenges such as reduced river flow and eutrophication, there is limited knowledge of organic matter fate and nutrient cycling in this system. Understanding nutrient movement and transformation within the Coorong is crucial for effective ecosystem management. This study applied diffusive equilibrium in thin films (DET) and diffusive gradient in thin films (DGT) techniques to measure dissolved nutrients (ammonium and phosphate), dissolved ferrous iron, and sulfide in sediment porewaters across a strong salinity gradient. Sampling sites were selected to capture different environmental conditions, including areas colonised by microphytobenthos and the aquatic macrophyte Ruppia tuberosa (hereafter called Ruppia). Concentration profiles were examined in both light and dark conditions to assess biotic influences on nutrient dynamics and sediment redox conditions. Sediment porewaters in deeper sites of the South Lagoon exhibited high ammonium (941-1718μmol/L), phosphate (83-171μmol/L), and sulfide (66-79μmol/L) concentrations, with negligible nitrate, indicating highly anoxic conditions unsuitable for most benthic fauna. Shallow sediments showed varying concentrations of ammonium, phosphate, dissolved ferrous iron, and sulfide across different sites and depths, influenced by Ruppia and microphytobenthos. The site colonised by Ruppia contained the lowest porewater ammonium concentrations (∼30μmol/L), suggesting that macrophyte presence can mitigate nutrient buildup in sediments. These findings indicate that sediment quality and nutrient cycling in the South Lagoon may be improved by enhancing the presence and biomass of aquatic macrophytes and macroinvertebrates.

Sediment composition influences microplastic trapping in seagrass meadows.

Sediment composition influences microplastic trapping in seagrass meadows.

Testing Macrophyte-Based Assessment Tools Developed Under the EU Water Framework Directive for Application in a Caucasus Region Country (Armenia)

The UN framework of “Integrated Water Resources Management” recommends countries establish a sustainable management of their water resources, which relies on the availability of proper assessment indexes for the ecological status of surface waters. Such indexes have been developed by many EU countries under the EU Water Framework Directive. Non-EU countries may be interested in adapting such assessment tools. Hence, we describe here a test of three macrophyte-based assessment tools developed in EU countries for use in Armenia. All three indices were tested in a regionally adapted version where local species were entered into reference taxonomic lists, river types were assigned, and matching exercises of the results with benthic macroinvertebrates and physical and chemical parameters of the rivers were performed. The results show that the three tested assessment tools produced similar spatial patterns of ecological status changes, while the adapted version of the MTR index had the highest number of significant correlations with various metrics of macrozoobenthos and hydro-chemical parameters. We conclude that assessment scores for rivers based on macrophytes can be used for rivers of the Caucasus after regional adaptation of the reference macrophyte list. We recommend that the modified MTR index be introduced into the national hydrobiological system of Armenia after some additional adaptations.

A comprehensive evaluation of the ecological status of Wadi Mariout ponds, Egypt

The present study is the first pioneer study on the ecological status of the Wadi Mariout ponds in the southern part of the Mediterranean Sea, Egypt. The physicochemical variables referred to brackish water (salinity: 12.28–16‰). The WQI indicated a lower water quality status in the western basin than the eastern one. The average TSI values (64.61 and 63.52) refer to high ecological productivity and poor water quality. However, the Arithmetic Water Quality Index (Ar-WQI) indicates the excellent water quality of the eastern pond for aquatic life, while the water quality of the western pond varies from good to very poor. The predominant groups’ species and low biodiversity indices of phytoplankton (1.29–2.2), zooplankton (1.23–1.93), and macroinvertebrates (0.45–1.85), as well as the biochemical composition of phytoplankton, reveal a high protein-carbohydrate ratio (> 11), indicating eutrophication conditions. Also, the biotic measurements show that the phytoplankton (70.7 × 106 Ind.l−1) and zooplankton (23.23 × 105 Ind.m−3) communities were more diverse and flourished in the western basin. Nevertheless, the macrobenthic invertebrates varied more in the eastern basin, 31,284 org.m−2, in compared to 5750 org.m−2 in the western one. The phytoplankton community was dominated by Chlorophyta and Cyanobacteria (79.5–93%), zooplankton by Rotifera (62.5–86.3%), and macrobenthos by Mollusca (62%) at the western basin and Annelida (38%) at the eastern one. The total bacteria count and fecal coliform value were rare in Wadi Mariout water. On the other hand, the sediment samples have more total coliform (15–3348 cfug−1) than the water (0–12 MPN/100). Wadi Mariout ponds, similar to Egyptian Delta lakes, suffer from the eutrophication phenomenon, which must be treated by controlling the feeding wastewater supplies of the ponds. The study sheds light on the current environmental status of Wadi Mariout lakes, serving as the first comprehensive study to assess water quality, record and classify biodiversity, and provide a precise assessment of the water body’s situation. This will facilitate the effective management of these important Egyptian lakes in the future.

Sublittoral Macrobenthic Communities of Storfjord (Eastern Svalbard) and Factors Influencing Their Distribution and Structure.

Seafloor communities along the eastern Svalbard coast remain poorly studied. To address this gap, we sampled benthic organisms on the soft sediments of Storfjord in 2017 and 2019, a large fjord predominantly influenced by cold Arctic waters, to study the local fauna and identify the key environmental drivers shaping community structure. In total, 314 taxa were recorded, with an increase in abundance (from 3923 to 8977 ind. m-2, mean 6090 ind. m-2) and a decline in biomass (ranging from 265 to 104 g m-2, mean 188 g m-2) toward the outer part of the fjord. However, no clear spatial trends were observed for alpha diversity (approximately 100 species per 0.3 m2) or the Shannon index (mean 3 per station). The primary factors influencing benthic abundance were the duration of the ice-free period (IFP) and the degree of siltation (DS), both of which are proxies for trophic conditions. The prevailing taxa displayed a high tolerance to temperature fluctuations and seasonal variability in nutrient inputs. Benthic biomass showed a negative relationship with IFP, DS, and water depth, but it was positively correlated with the proportion of fine-grained sediment. The Yoldia hyperborea community (mean abundance: 3700 ind. m-2, mean biomass: 227 g m-2) was associated with Arctic waters characterized by higher inorganic suspension loads. In contrast, areas with reduced or weaker sedimentation were dominated by the communities of Maldane sarsi (6212 ind m-2, 226 g m-2) and Maldane sarsi + Nemertini g.sp. (5568 ind m-2, 165 g m-2). The Spiochaetopterus typicus community (7824 ind m-2, 139 g m-2) was observed in areas under moderate influence of Atlantic waters, characterized by low sedimentation rates and increased fresh detritus flux.

EXISTING CONDITION OF GASTROPODS COMMUNITY IN COASTAL AREAS AFFECTED BY NICKEL OVERBURDEN IN POMALAA DISTRICT, SOUTHEAST SULAWESI PROVINCE, INDONESIA

ARTICLE HIGHLIGHT The present investigation provides substantiated empirical evidence demonstrating that nickel extraction operations have exerted considerable detrimental effects on the ecological integrity of the Pomalaa coastal region in Southeast Sulawesi. Environmental degradation and disruption of ecological equilibrium have been observed as direct consequences of persistent overburden waste disposal. The introduction of mining overburden into the Pomalaa coastal ecosystem has resulted in the extirpation of critical gastropod taxa and significant population reductions among persisting species when compared with control sites featuring undisturbed substrate conditions. The documented diminished gastropod population densities within nickel mining-affected zones serve as biological indicators of profound environmental deterioration attributable to these industrial activities. ABSTRACT Pomalaa District is the largest existing nickel mining center in Southeast Sulawesi Province, Indonesia. Pollutants from various anthropogenic activities, especially nickel mining overburden, end up in the Pomalaa coastal area. This research aimed to determine the structure of the gastropods community in the impacted area and reference site. This research was carried out in the Pomalaa coastal area, Kolaka Regency, from June to October 2023. Research stations were determined using purposive sampling method and simple random sampling techniques. On-site collecting gastropods samples were carried out manually (handpicking method). Impacted area and reference site showed significant differences in the number of species (16 and 21 species), presence, and density of gastropods, even though their respective ecological index categories were relatively the same (H' = 1.92 &amp; 2.72; R = 2.93 &amp; 3.41; E = 0.55 &amp; 0.78; C = 0.001 &amp; 0.04). In the impacted area, the density of gastropods was very low (1 - 3 ind./m2), whereas at the reference site, the density reached 10 - 30 ind./m2. Gastropods inhabiting rocks or hard substrates, were relatively unaffected by the overburden, proven by stable population with a high density of 45 - 115 ind./m2. Nickel overburden input flowing to the Pomalaa coastal area greatly influenced the gastropods community in terms of species composition and density. On the other hand, the habitat (substrate) of gastropods as benthic organisms was covered and degraded by overburden piles up to 15 - 30 cm deep, which was still increasing over time. On the other hand, in the reference site area, the condition was inversely proportional.

Phylogenetic diversity and distribution patterns of ammonia-oxidizing microorganisms in marine environments

Abstract Ammonia-oxidizing archaea (AOA) and bacteria (AOB) are abundant in the global ocean, playing a crucial role in marine nitrogen cycling through nitrification. Despite extensive studies using the ammonia monooxygenase α-subunit (amoA) gene, our understanding of their distribution patterns in marine habitats remains limited. This study offers the first integrative framework to assess the diversity and biogeography of ammonia-oxidizing communities across different marine habitats, based on a meta-analysis and phylogenetic examination of archaeal and bacterial amoA sequences from public databases. Most sequences were retrieved from estuarine sediments and coastal waters, while habitats such as pelagic open ocean, OMZ, deep sea, hydrothermal vents, and benthic organisms are underexplored. AOA exhibited higher phylogenetic diversity than AOB, with many unclassified AOA-amoA sequences likely representing novel clades. The dominant AOA clades were Ca. Nitrosopelagicus, Nitrosoarchaeum, and Nitrosopumilus, while Nitrosospira was the predominant clade among AOB. AOA show greater ecological versatility, thriving in nutrient-poor and low-oxygen environments, whereas AOB are more prevalent in nutrient-rich estuarine habitats. Further research is needed to better understand the ecological roles of novel AOA clades and the contributions of AOB in less-explored marine habitats.

Habitat heterogeneity overrides local processes to drive the species–area relationship of benthic macroinvertebrates in shallow floodplain lakes

The species–area relationship (SAR) on islands describes how the numbers of species increase with increasing island size (or island‐like habitat, such as lakes). Despite its conceptual importance, there is considerable uncertainty surrounding its shape in freshwater lakes, as well as the potential mechanisms that underlie the SAR. Here, we used standardized sampling data of benthic macroinvertebrates from 81 shallow lakes in the Yangtze–Huai floodplain of China to evaluate its shape and disentangle several mechanisms (e.g. passive sampling, colonization‐extinction dynamics and heterogeneity) underlying the SAR. At the whole‐lake level, we found an increase in the total species richness with increasing lake area, as well as an increase in rarefied richness controlling for sampling effort. However, within single samples, diversity was negatively related to lake area. This scale‐dependence is because within‐lake β‐diversity increased with lake area, suggesting that heterogeneity overrides local processes to generate the positive SAR. These patterns were only evident for measures of diversity that equally weigh common and rare species (i.e. species richness), and disappeared when diversity measures that weigh common species more heavily were used. This suggests that the influence of heterogeneity on the SAR was largely via its influence on rarer species and their turnover in larger lakes. Overall, our result that heterogeneity was the primary driver of the positive SAR in this system provides an important baseline for making predictions about biodiversity changes with ongoing habitat loss.

Seasonal variations in feeding ecology and mercury contamination of golden cuttlefish (Sepia esculenta) in the coastal waters of China.

Seasonal variations in feeding ecology and mercury contamination of golden cuttlefish (Sepia esculenta) in the coastal waters of China.

Taxonomic and functional responses of benthic macroinvertebrates to wastewater effluents in the receiving river of ecologically vulnerable karst areas in Southwest China.

Taxonomic and functional responses of benthic macroinvertebrates to wastewater effluents in the receiving river of ecologically vulnerable karst areas in Southwest China.

Heavy metals contamination in Jakarta Bay sediment: geoaccumulation assessment and implication for environmental health.

Heavy metals contamination in Jakarta Bay sediment: geoaccumulation assessment and implication for environmental health.