Natural Benthic Communities Research Articles

Exposure of blue crab (Callinectes sapidus) to modified clay treatment of Karenia brevis as a bloom control strategy

Harmful algal blooms (HABs) of the toxic marine dinoflagellate Karenia brevis, commonly called red tides, are an ongoing threat to human health and marine ecosystems in Florida. Clay flocculation is a standard control strategy for marine HABs in China and Korea and is currently being assessed for use in the United States. We evaluated the effects of a PAC-modified clay called Modified Clay II on mortality, eyestalk reflexes, and righting reflexes of 48 adult blue crabs (Callinectes sapidus). Crabs were exposed to clay alone (0.5 g L − 1), untreated K. brevis (1 × 106 cells L − 1), or a combination of K. brevis and clay for eight days. Clay treatment reduced cell concentrations in the water column by 95% after 24 h. We detected no significant differences in mortality, righting reflexes, or eyestalk reflexes between treatments. Our results indicate that the clay alone is not harmful to adult crabs at typical treatment concentrations within the measured time frame, and that treatment of K. brevis with this clay appears to have a negligible impact on crab mortality and the reflex variables we measured. These results suggest that Modified Clay II may be a viable option to treat K. brevis blooms without impacting adult blue crab populations. Additional controlled experiments and field tests are needed to further evaluate the impact of clay on natural benthic communities.

Possible Interactions between Invasive Caulerpa Taxa and Native Macrozoobenthos: The Case Study of Favignana Island

Biological invasions are widely recognized as a major threat to native biodiversity, ecosystem functioning and services. Amongst the NIS recorded in the Mediterranean Sea, Chlorophyta species belonging to the genus Caulerpa (Caulerpa cylindracea, C. taxifolia and C. taxifolia var. distichophylla) have raised serious concerns due to their potential or ascertained impact on native benthic communities. During surveys carried out to monitor the occurrence and the coverage of Caulerpa species along the coasts of Favignana Island (Egadi Islands Marine Protected Area), we observed variations in C. cylindracea and C. taxifolia coverage and also some large invertebrates overgrown with thalli of both species.

The complete mitochondrial genome of the invasive cyanobacteriosponge Terpios hoshinota (Demospongiae, Suberitida, Suberitidae)

The cyanobacteriosponge Terpios hoshinota occurs on tropical reefs throughout the Indo-Pacific. The species encrusts live coral, and other benthos, and is considered a pest species that can threaten the health and productivity of locally native benthic communities on coral reefs. Here we assemble a complete mitochondrial genome to aid further research into the range expansion of this species. The circular genome was 20,504 bp in length and encoded 14 protein-coding genes, two ribosomal RNA (rRNA) genes, and 25 transfer RNA (tRNA) genes. A phylogenetic analysis based on the concatenated sequences of 14 protein-coding genes of 12 members of the subclass Heteroscleromorpha including the newly sequenced T. hoshinota, suggests further taxonomic revisions within the order Suberitida may be warranted.

The effects of an invasive soft coral on the structure of native benthic communities

Species invasion is a major threat to marine biodiversity and function; thus, studying the effects of recently reported exotic species is extremely important. Several soft coral species (Alcyonacea) have invaded the Atlantic Ocean but their effects are poorly known. Here, we investigated the effects of the invasive species Sarcothelia sp. (Alcyonacea, Xeniidae) on native benthic shallow reef communities in Brazil. We hypothesized that increasing Sarcothelia sp. abundance would be related to species richness decreases and native community structure changes. Multivariate analysis showed significant dissimilarity between invaded (high Sarcothelia sp. abundance) and non-invaded areas (high abundance of the octocoral Neospongodes atlantica and zoantharians). The invaded area showed less species composition variability (i.e., homogenization) than non-invaded ones. Within the invaded area we observed that Sarcothelia sp. abundance reduced species richness. The lowest native benthic richness (10 taxa) was observed in a transect with the highest invader cover, while the transect with the lowest Sarcothelia sp. cover presented 26 native taxa. These findings are likely related to the invasive novel functional traits, i.e., invader growth form and allelochemicals. A clear inverse abundance pattern between invasive Sarcothelia sp. and N. atlantica, indicated an intense competition between octocorals. Our study showed remarkable evidence of negative impacts of invasive soft corals on reef biodiversity. There is an urgent need for experiments evaluating changes in different ecological processes and to implement management actions.

Stream Mesocosm Experiments Show no Protective Effects of Calcium on Copper Toxicity to Macroinvertebrates.

Although the concept and modeling of metal bioavailability and toxicity have been well developed based largely on laboratory experiments with standard test species, additional evidence is required to demonstrate their applicability for macroinvertebrates typically found in natural lotic ecosystems. We conducted 10‐day stream mesocosm experiments to test the hypothesis that increased water hardness (in the present study, the calcium [Ca] concentration was increased by adding CaCl2) would mitigate the effects of copper (Cu) on natural benthic macroinvertebrate communities. Exposure of macroinvertebrate communities to 25 μg/L Cu for 10 days in stream mesocosm experiments resulted in significant decreases in total abundance, in number of taxa, and in abundance of many macroinvertebrate taxa. However, the addition of Ca to stream mesocosms and the associated increase in water hardness up to 250 mg/L CaCO3 did not mitigate these effects of Cu on macroinvertebrate communities. The results showed that the hardness‐based water quality criteria for Cu of the US Environmental Protection Agency were not protective under the conditions of relatively high hardness, low alkalinity, and circumneutral pH. In contrast, the water quality criteria based on the biotic ligand model predicted little protective effects of Ca on Cu toxicity, which is consistent with our results. Additional experiments are required to understand the influence of modifying factors on the toxicity of metals to macroinvertebrate communities. Environ Toxicol Chem 2022;41:1304–1310. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Non-native Dreissena associated with increased native benthic community abundance with greater lake depth

Although the typical interaction between non-native invasive species and native species is considered to be negative, in some cases, non-native species may facilitate native species. Zebra and quagga mussels (Dreissena spp.) are aggressive invaders in freshwater systems, and they can alter energy flow by diverting nutrients from pelagic to benthic food-webs. In the last two decades, quagga mussels have largely replaced zebra mussels in shallow regions of the Laurentian Great Lakes and colonized deeper waters previously devoid of all dreissenids. Here, we aim to characterize potential positive effects of dreissenids in relation to depth on the benthic community in lakes Michigan and Huron. For this study, we used benthic survey data collected from Lake Michigan in 2015 and Lake Huron in 2017 and annual U.S. EPA Great Lakes National Program Office Long-term Biology Monitoring Program data for both lakes from 1998 to 2019. Benthic species richness and abundance (excluding dreissenids) in both lakes were almost three-fold higher in the nearshore (<70 m) compared to offshore (>70 m) communities. We found that, even though abundance of benthic invertebrates decreased with increased depth, total benthos density and biomass were higher in the presence than in the absence of quagga mussels in both lakes. Moreover, increased quagga mussel density and biomass with depth offset the lower benthos density and biomass at deeper depths, and samples with dreissenids had high densities of oligochaetes in both nearshore and offshore communities. These patterns are consistent with facilitative effects of quagga mussels on both shallow and deep-water benthic communities.

Use of carbon dioxide to prevent zebra mussel (Dreissena polymorpha) settlement and effects on native mussels (Order Unionoida) and benthic communities

Use of carbon dioxide to prevent zebra mussel (Dreissena polymorpha) settlement and effects on native mussels (Order Unionoida) and benthic communities

Nitrogen eutrophication particularly promotes turf algae in coral reefs of the central Red Sea.

While various sources increasingly release nutrients to the Red Sea, knowledge about their effects on benthic coral reef communities is scarce. Here, we provide the first comparative assessment of the response of all major benthic groups (hard and soft corals, turf algae and reef sands—together accounting for 80% of the benthic reef community) to in-situ eutrophication in a central Red Sea coral reef. For 8 weeks, dissolved inorganic nitrogen (DIN) concentrations were experimentally increased 3-fold above environmental background concentrations around natural benthic reef communities using a slow release fertilizer with 15% total nitrogen (N) content. We investigated which major functional groups took up the available N, and how this changed organic carbon (Corg) and N contents using elemental and stable isotope measurements. Findings revealed that hard corals (in their tissue), soft corals and turf algae incorporated fertilizer N as indicated by significant increases in δ15N by 8%, 27% and 28%, respectively. Among the investigated groups, Corg content significantly increased in sediments (+24%) and in turf algae (+33%). Altogether, this suggests that among the benthic organisms only turf algae were limited by N availability and thus benefited most from N addition. Thereby, based on higher Corg content, turf algae potentially gained competitive advantage over, for example, hard corals. Local management should, thus, particularly address DIN eutrophication by coastal development and consider the role of turf algae as potential bioindicator for eutrophication.

A heatwave increases turnover and regional dominance in microbenthic metacommunities

While the effect of the global biodiversity crisis on local species loss is still debated, there is empirical evidence for major changes in local biodiversity attributed to increased species turnover. In communities exposed to a climate stressor, species turnover can lead to increased dominance of well-adapted species and consequently to an overall decline in species diversity. Despite the known importance of species turnover for community dynamics and functioning, experimental results on the connection between biodiversity loss and species turnover are scarce. We still do not fully understand which specific factors increase the rate of change in species composition, especially when considering natural compared to artificially lab assembled communities. In the present study, we experimentally tested whether a heatwave and dispersal increased species turnover and decreased species diversity in natural benthic diatom communities with different initial species compositions. We found that on the local scale, dispersal had overall positive effects on species richness while the relationship between exposure to the heatwave, species turnover, and diversity depended on initial community composition. However, on the regional (i.e. metacommunity) scale, exposure to the heatwave and dispersal both increased turnover and decreased Shannon diversity by almost 50%. Turnover in these metacommunities was not caused by a loss of species, but rather by a change in dominance patterns leading to homogenization, and consequently decreased diversity. Our study shows that climate change can destabilize community composition and degrade species diversity, but still after ca. 15 generations does not decrease the number of species in the community, demonstrating that the response of species diversity and richness to changing conditions can be fundamentally decoupled on ecological time scales.

Ecological Characteristic of Brown Algae Communities – Potential Aquaculture Objects

The benthic brown algae communities in coastal zone of southwest part of the Barents Sea have been studied. Research was carried out on the structure of benthic phytocenosis on the Murman coast in which edificators are brown seaweeds of the orders Fucales and Laminariales. The study focused on the dynamics of populations, size and age features against influence of the basic ecological factors on growth of commercial seaweeds - potential objects of mariculture. It is established that benthic phytocenosis on certain biotopes of littoral and sublittoral zones characterize by relativity high species diversity. The populations of commercial seaweeds form the multilevel structured benthic communities. The algae populations create topical, trophic and mediative connections which provide for steady stability of benthic communities. The use of plant community rather than individual algae species as biological indicators and biomonitors allows obtaining more complete information about the ecological state of benthic coastal ecosystem. The information collected can be used for the biological monitoring of marine bioresources in natural benthic communities, and also for cultivation of brown seaweeds under conditions of aquaculture.

The Introduced Fanworm, Sabella spallanzanii, Alters Soft Sediment Macrofauna and Bacterial Communities

The Mediterranean fanworm, Sabella spallanzanii, is an introduced and established “unwanted species” in New Zealand, subject to nationwide targeted surveillance in port, marina, urban and natural environments. S. spallanzanii has the potential to change soft-sediment benthic habitats due to the physical presence of the fanworm’s tube and associated biological activities, particularly suspension feeding and bio-deposition. A 6-month field experiment was conducted to investigate the impacts of S. spallanzanii on existing communities within invaded soft-sediment habitats. Macrofaunal communities were assessed using traditional sampling and taxonomy while microbial and eukaryotic communities were characterised using metabarcoding of 16S and 18S ribosomal genes, respectively. Live and mimic S. spallanzanii were transplanted at different densities (10 - 50 individuals per m2) into experimental plots with existing assemblages, to test for potential biological and/or physical effects on benthic communities. Analyses revealed consistent, significant differences in macrofaunal, eukaryote and bacterial assemblages in the presence of live S. spallanzanii and mimics, indicating that these effects are brought about by biological and physical functions associated with the worms. The presence of S. spallanzanii did not alter total abundance and taxa richness of benthic assemblages but resulted in compositional differences. Changes in the structure of native benthic communities, as indicate by this study, can potentially impact functioning of soft-sediment habitats, through alterations to nutrient cycling, bioturbation and benthic-pelagic coupling. Quantitative measurements of impacts are crucial to understand the trajectory of marine invasions, their roles in re-structuring communities, and to guide management efforts.

Widespread cryptic viral infections in lotic biofilms

Viruses have important impacts on aquatic microbial ecology and have been studied at length in the global ocean. However, the roles of bacteriophages in lotic ecosystems, particularly in benthic biofilms, have been largely under-studied. The main goals of this work were to determine whether viruses are consistent members of natural benthic biofilm communities of freshwater streams; whether temperate phages are present and active in such biofilms; and whether community profiling approaches like RAPD-PCR can be adapted to characterize biofilm virus communities. Results from both field and laboratory experiments suggest that viruses are consistent members of lotic biofilm communities. Interestingly, prophage induction was statistically significant but only a small percentage of the total bacterial population appeared to harbor prophage or engaged in induction. Finally, while the use of RAPD-PCR for the community level profiling of biofilm viral communities suggests temporal change in response to biofilm maturity, further refinements are required for broad-scale quantitative application.

Indirect Effects of Iron Oxide on Stream Benthic Communities: Capturing Ecological Complexity with Controlled Mesocosm Experiments.

Ferric iron (Fe(III)) oxyhydroxides commonly precipitate at neutral pH and in highly oxygenated conditions in waterways receiving acid mine drainage, degrading stream benthic communities by smothering of habitat, primary producers, and aquatic invertebrates. Stream mesocosms were used to expose naturally colonized benthic communities to a gradient of ferric Fe (0-15 mg/L) for 14 days to estimate the effects of Fe precipitates on primary production, larval and emerging adult aquatic insects, and the macroinvertebrate community structure. Community composition was significantly altered at concentrations near or below the US Environmental Protection Agency chronic Fe criterion (1.0 mg/L). Iron exposure significantly decreased larval and emerging adult abundances of Baetidae (mayfly) and Chironomidae (Diptera); however, while Simuliidae (Diptera) larvae were not reduced by the Fe treatments, abundance of emerged adults significantly decreased. Iron substantially decreased the colonization biomass of green algae and diatoms, with estimated EC20 values well below the Fe criterion. In contrast, cyanobacteria were stimulated with increasing Fe concentration. By integrating environmentally realistic exposure conditions to native benthic communities that have complex structural and functional responses, the ability to predict the effects of Fe in the field is improved. Traditional toxicity testing methodologies were not developed to evaluate indirect effects of contaminants, and modernized approaches such as community mesocosm experiments better characterize and predict responses in aquatic ecosystems outside the laboratory. Therefore, the development of water quality standards would benefit by including mesocosm testing results.

Quantifying bioturbation across coastal seascapes: Habitat characteristics modify effects of macrofaunal communities

Bioturbation by benthic macrofauna communities plays a significant role in the setting and maintenance of important ecosystem functions and the delivery of associated ecosystem services. We investigated the context-dependence of bioturbation performed by natural benthic communities in the coastal northern Baltic Sea by quantifying three bioturbation metrics (particle mixing intensity, surface sediment reworking and bioturbation depth) across 18 sites ranging from cohesive muddy sediments to non-cohesive coarse sands, while accounting for the complexity of natural communities and habitat characteristics. We identified two distinct patterns of bioturbation; in fine sediments bioturbation rates were highly variable and in coarse sediments bioturbation rates were less variable and characterized by lower maximal values. Using distance-based linear multiple regressions, we found that 75.5% of the variance in bioturbation rates in fine sediment could be explained by key functional groups/species abundance and/or biomass (i.e. biomass of the gallery-diffusors and abundances of biodiffusors, surface modifiers, conveyors and gallery diffusors, respectively). In coarse sediment, 47.8% of the variance in bioturbation rates could be explained by a combination of environmental factors (grain size, organic matter content, buried plant material) and faunal functional groups, although fauna alone explained only 13% of this variance. Bioturbation in fine sediments was therefore more predictable based on the composition of benthic fauna. In coarse sediment, the bioturbation activities of benthic fauna were strongly modified by habitat characteristics (including the presence of buried plant material, sediment organic content and grain size) whereas in fine sediments this was not the case. Our results therefore highlight that variability in spatial patterns of bioturbation is a result of complex relationships between macrofauna community structure, sediment type and other habitat characteristics, likely modifying bioturbation performance of individual fauna.

¹H NMR Spectroscopy and MVA to Evaluate the Effects of Caulerpin-Based Diet on Diplodus sargus Lipid Profiles.

The biological invasion of the green algae Caulerpa cylindracea represents a serious scientific and public issue in the Mediterranean Sea, essentially due to strong modifications both to habitat structure and native benthic communities. Although alterations in health status and changes in flesh quality of some marine species (dietary exposed to C. cylindracea) have been observed, no studies on cause-effect relationships have been carried out. Here, for the first time, through a controlled feeding experiment followed by 1H NMR Spectroscopy and multivariate analysis (PCA, OPLS-DA), we showed that caulerpin taken with diet is directly responsible of changes observed in metabolic profile of fish flesh, including alteration of lipid metabolism, in particular with a reduction of ω3 PUFA content. The potential of caulerpin to directly modulate lipid metabolism opens up new questions about causal mechanism triggered by algal metabolite also in view of a possible exploitation in the nutraceutical/medical field.

Performance of an in situ activated carbon treatment to reduce PCB availability in an active harbor.

In situ amendment of surface sediment with activated carbon is a promising technique for reducing the availability of hydrophobic organic compounds in surface sediment. The present study evaluated the performance of a logistically challenging activated carbon placement in a high-energy hydrodynamic environment adjacent to and beneath a pier in an active military harbor. Measurements conducted preamendment and 10, 21, and 33 months (mo) postamendment using in situ exposures of benthic invertebrates and passive samplers indicated that the targeted 4% (by weight) addition of activated carbon (particle diameter ≤74 µm) in the uppermost 10 cm of surface sediment reduced polychlorinated biphenyl availability by an average (± standard deviation) of 81 ± 11% in the first 10 mo after amendment. The final monitoring event (33 mo after amendment) indicated an approximate 90 ± 6% reduction in availability, reflecting a slight increase in performance and showing the stability of the amendment. Benthic invertebrate census and sediment profile imagery did not indicate significant differences in benthic community ecological metrics among the preamendment and 3 postamendment monitoring events, supporting existing scientific literature that this approximate activated carbon dosage level does not significantly impair native benthic invertebrate communities. Recommendations for optimizing typical site-specific assessments of activated carbon performance are also discussed and include quantifying reductions in availability and confirming placement of activated carbon. Environ Toxicol Chem 2018;37:1767-1777. Published 2018 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Structural and functional responses of periphyton and macroinvertebrate communities to ferric Fe, Cu, and Zn in stream mesocosms.

Two mesocosm experiments were conducted to examine effects of ferric iron (Fe) and mixtures of ferric Fe with aqueous metals (Cu, Zn) on stream benthic communities. Naturally colonized benthic communities were exposed to a gradient of ferric Fe (0, 0.4, 1.0, 2.5, 6.2, and 15.6 mg/L) that bracketed the current US Environmental Protection Agency water quality criterion value (1.0 mg/L). After 10 d of exposure to ferric Fe, total macroinvertebrate abundance, number of taxa, and abundance of all major macroinvertebrate groups (Ephemeroptera, Plecoptera, Trichoptera, and Diptera) were significantly reduced. Heptageniid mayflies and chironomids were especially sensitive to Fe oxide deposition and were significantly reduced at 0.4 and 1.0 mg/L total Fe, respectively. In a second mesocosm experiment, periphyton and macroinvertebrate communities were exposed to ferric Fe (0.60 mg/L) with or without aqueous Cu and Zn at 2 treatment levels: low (0.01 mg/L Cu + 0.1 mg/L Zn) and high (0.05 mg/L Cu + 0.5 mg/L Zn). In contrast to previous research, we observed no evidence of a protective effect of Fe on toxicity of metals. Growth rates and protein content of periphyton were significantly reduced by both ferric Fe and aqueous metals, whereas abundance of heptageniid mayflies (Cinygmula) and whole community metabolism were significantly reduced by ferric Fe alone. We hypothesize that Fe oxides inhibited algal growth and enhanced metal accumulation, leading to a reduction in the quantity and quality of food resources for grazers. Mesocosm experiments conducted using natural benthic communities provide a unique opportunity to quantify the relative importance of indirect physical effects and to develop a better understanding of the relationship between basal food resources and consumers in natural stream ecosystems. Environ Toxicol Chem 2018;37:1320-1329. © 2017 SETAC.

Assessing the ecological health status using macrobenthic communities of tropical coastal water

ABSTRACTThe relative contributions of natural and anthropogenic fluctuations are different in shaping habitat health status and natural benthic communities in tropical coastal water. Understanding responses of coastal benthic communities to these fluctuations are still equivocal and thus available data are inadequate. Here, multiple analytical approaches were used to address the significant risk factors and their impacts on coastal benthic habitat health through space and time. A total abundance of 1436 ± 612 individuals of 33 benthic species were counted and identified from 22 sampling stations across eight sampling periods over the two years of study. Bioassay results showed that the benthic community is moderately exposed to anthropogenic pollutants in Klang Strait coastal water. The results showed that there were no significant temporal changes of habitat health status and macrobenthic community structure; however, spatial changes were significant and synchronized with anthropogenic and natural fluctuations. This study demonstrates that Cd and Hg levels and sediment characteristics played the primary role in shaping the habitat health and macrobenthic assemblages, whereas the influence of other factors were insignificant.

Parámetros poblacionales del erizo de mar Arbacia dufresnii (Arbacioida, Arbaciidae) en golfos norpatagónicos invadidos por el alga Undaria pinnatífida (Laminariales, Alariaceae)

Population parameters of the sea urchin Arbacia dufresnii (Blainville, 1825) from North Patagonian gulfs invaded by kelp Undaria pinnatifida (Harvey) Suringar, 1873. The Asian seaweed Undaria pinnatifida invaded Argentina in 1992 (Golfo Nuevo, Patagonia). Its range has expanded and it has changed the native benthic community. Sea urchins are usually generalist herbivores that have a key role in controlling seaweeds. Arbacia dufresnii is the most abundant sea urchin in the coastal areas of northern Patagonia. The aim of this study was to relate the population parameters of A. dufresnii to the presence of the invasive seaweed. In 2012 we sampled sites with different invasion stages (advanced: Golfo Nuevo, recently invaded: San José Gulf, Punta Tehuelche; no invasion: San José Gulf, Zona 39). Sea urchin density was higher in the invaded sites and varied with the seaweed cycle. In addition, there were variations in the size distribution in the invaded sites. The invasive algae probably affects urchin populations because it is a new source of food that changes environmental structure (it provides microhabitat for new recruits) and affects the native benthic community. Rev. Biol. Trop. 65(Suppl. 1): S101-S112. Epub 2017 November 01.

Effects of magnesium chloride road deicer on montane stream benthic communities

Montane streams often intercept and run parallel to roads and highways where road deicer is seasonally applied for snow and ice removal. This research used stream mesocosms to evaluate the effects of MgCl2 road deicer to a Rocky Mountain stream benthic community in Colorado, USA. Measured responses included macroinvertebrate drift, community composition metrics, and macroinvertebrate biomass after a 10-day exposure. Natural benthic communities were exposed to concentrations of liquid MgCl2 road deicer that bracketed the U.S. Environmental Protection Agency (U.S. EPA) surface water chronic chloride ‘aquatic life criteria’ (230 mg Cl−/l). Results showed no effects on macroinvertebrate drift, but significant reductions in abundance, taxa richness, and community biomass. Specifically, stonefly (Plecoptera) and mayfly (Ephemeroptera) abundance decreased at Cl− concentrations below the U.S. EPA chronic chloride water quality standard, and at concentrations substantially lower than those generated from traditional laboratory toxicity tests. However, caddisflies (Trichoptera), midges (Chironomidae) and other dipterans were tolerant to all MgCl2 treatments. We conclude that MgCl2 road deicer has the potential to impair montane stream benthic communities at relatively low ionic concentrations, and regulatory agencies should manage for and establish regionally appropriate application rates for this stressor.