Benthic Macrofaunal Assemblages Research Articles

Lower diversity in benthic macrofaunal assemblages associated with increasing riparian deforestation in first-order lowland tropical streams

ABSTRACT In aquatic ecosystems, benthic macroinvertebrates are strongly influenced by riparian habitat quality. We investigated associations between riparian deforestation, stream habitat variables and benthic macroinvertebrate assemblage structure, particularly sensitive taxa. We sampled macroinvertebrates and physical-chemical variables during both the dry and wet seasons at three sites, each with low, medium, and high levels of riparian deforestation, in each of three first-order streams in the lower zone of the Caeté river in eastern Amazonia, Brazil. The relationships were examined using Generalized Linear Mixed-Models (GLMM) and multivariate analysis. Macroinvertebrate families most associated with deforestation levels were determined by Indicator Species Analysis. We hypothesized that lower riparian deforestation is associated with greater diversity, especially of sensitive taxa, and lower dominance. A total of 3,427 macroinvertebrates distributed in 54 families were found, of which 25 were sensitive taxa. Sites with high deforestation, associated with Glossiphonidae, Tubificidae, and Naididae, differed from those with medium (associated with Limnephilidae) and low (associated with Polycentropodidae and Hydropsychidae) deforestation. Families and abundance of EPTC (Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera) were lower at high deforestation, with significant losses of taxa compared to the whole assemblage. In Caeté headwaters, deforestation is an important factor for structuring benthic macroinvertebrate assemblages.

Macrobenthic infaunal assemblage structure in nearshore and offshore seabeds of Ghana

Abstract. Commey NA, Armah AK, Lamptey E. 2021. Macrobenthic infaunal assemblage structure in nearshore and offshore seabeds of Ghana. Indo Pac J Ocean Life 5: 50-60. This research aimed to compare and contrast the sediment properties and benthic macrofaunal assemblage composition of nearshore and offshore habitats. Also, the existing state of benthic macrofaunal assemblages in the Jubilee Fields, Ghana in 2015 is determined. A baseline is established for these communities before constructing a coal-powered plant in the nearshore area of Ekumfi Aboano, Ghana (deep-sea). The research was conducted in the shallower nearshore Ekumfi Aboano (average depth: 15 m) and deeper offshore portions of the Jubilee Fields (average depth: 1,250 m). A Van Veen grab was used to collect sediment samples from the nearshore area, while a box corer was used to collect samples from the deep water. PRIMER was used to look into the distribution of benthic macrofauna. Using GRADISTAT, it was determined that the nearshore sediment (mean grain size of 99.80 m) is fairly sorted with very fine sand. In contrast, offshore sediment (mean grain size of 109.79 m) was poorly sorted and comprised of extremely coarse silty fine sand. It was determined from studies of macrobenthic infauna that there were 11,131 individuals in the nearshore environment, with a density of 38 individuals/m2, and 22,105 individuals in the deep-sea environment, with a density of 47 individuals/m2. Data for the nearshore and offshore environments showed a total of 194 and 983 polychaetes, 827 and 696 crustaceans, 35 and 229 mollusks, 14 and 37 echinoderms, and 43 and 260 "others" (foraminiferans, nematodes, nemerteans, and sipunculids). Crustaceans > polychaetes > molluscs > others > echinoderms dominated the shallow Ekumfi seabed, whereas polychaetes > crustaceans > molluscs > others > echinoderms dominated the offshore Jubilee seabed. There were 116 species discovered close to shore, while 188 were discovered in the deep water. Both locations displayed a high level of diversity (H' > 4; 1-D > 0.9) and were evenly distributed (J' > 0.8). The nearshore was dominated by arthropods (74.30%), while the offshore was dominated by polychaetes (44.58%). A greater variety of macrobenthic infauna was found in the deep sea compared to the nearshore, with a difference of 75% between the two environments.

Using benthic macrofaunal assemblages to define habitat types on the northeast pacific sedimentary shelf and slope

Point sampling of soft sediment macrofauna was conducted across the shelf and upper slope in the northeastern Pacific Ocean off the United States Pacific Northwest coast to conduct a regional analysis of species composition and use species assemblages to define habitat types. Analyses focused on linking spatial variability in macrofauna assemblages with measured environmental parameters using nMDS plots and the LINKTREE routine in Primer. Depth was the primary structuring variable (i.e., macrofauna species assemblages first separated by depth) with sediment parameters (percent fines, grain size, and total organic carbon) secondary and nearly as statistically important. A depth break of ~90 m was the environmental variable that correlated with the greatest separation among our stations based on differences in macrofaunal assemblages, which is not a classically described depth break for shelf macrofauna. The next largest changes in assemblage composition were at 43 m and 200 m. Within each of these depth zones on the shelf, we detected significant differences in assemblages related to different sediment grain sizes. Below the 200 m break – a depth traditionally delineating the continental shelf and slope – subsequent changes in assemblage composition were detected at 221 m and 445 m depth breaks; further delineations in assemblages related to sediment parameters were not detected. Knowing how macrofaunal communities vary with grain size and depth can inform future site surveys, develop tools for mapping macrofauna habitat suitability based primarily on these physical factors, and develop hypotheses of how benthic communities might be affected by offshore projects.

Benthic macrofaunal assemblage in seagrass-mangrove complex and adjacent ecosystems of Punang-Sari Estuary, Lawas, Sarawak, Malaysia

Abstract. Al-Asif A, Hamli H, Abu Hena MK, Idris MH, Gerusu GJ, Ismail JB, Karim NU. 2020. Benthic macrofaunal assemblage in seagrass-mangrove complex and adjacent ecosystems of Punang-Sari Estuary, Lawas, Sarawak, Malaysia. Biodiversitas 21: 4606-4615. Present study dealt with the on faunal and in faunal assemblage from seagrass bed, mangrove area, and adjacent non-mangrove and seagrass (NMS) in Punang-Sari estuary, Lawas, Sarawak, Malaysia. Samples were collected from June to July 2019 by using quadrates and handpicking from the outside the sampling area to know the real checklist of surface macrofauna in this area. A ten-meter transect line was settled in three habitat areas where sampling was performed by putting three quadrates (0.35m×0.35m). Epifauna and infauna samples were collected from inside the quadrate and sieved using 0.4 mm mesh size sieve. A total of 111 species of gastropod (87 species from 30 families), bivalve (18 species from 9 families), Polychaeta (2 species), echinoderms (1 species), and crustacean (3 species) were recorded during the study period. Seagrass meadows comprised most diverse and abundant faunal (50 species) assemblage followed by mangrove habitats (48 species), and NMS (20 species). The dendrogram revealed two significant habitats in the sampling site. PCA analysis revealed, seagrass habitat sheltered a higher number of species followed by mangrove and NMS area. Jaccard similarity index revealed seagrass and mangrove habitats (0.42) contains the highest similar species amongst all habitats compared to mangrove and non-seagrass-mangrove area (0.26). Out of total species recorded (101), only ten species were reported as least concern, and 2 species hold deficient data status, and the rest are not evaluated. Bio-assemblage in seagrass habitat was found rich compared to other habitats, which could be useful for future ecological investigation and marine ranching.

Testing marine regional-scale hypotheses along the Yucatan continental shelf using soft-bottom macrofauna

Different hypotheses related to the regional-scale configuration of the Yucatan Continental Shelf (YCS) between the Gulf of Mexico (GoM) and the Caribbean Sea have been proposed. Hypotheses regarding its regional boundaries include: (i) an ecoregional boundary at Catoche Cape, dividing the Western Caribbean and the Southern GoM ecoregions; and (ii) a boundary within the Southern GoM ecoregion at 89°W, separating the West and Mid-Yucatan areas. We tested the hypothesis of no variation in benthic macrofaunal assemblages between regions delimited by the former boundaries using the species and functional traits of soft-bottom macrofauna. We considered that the depth and temporal environmental dynamics might interact with regional variations, generating complex benthic community patterns. The data were collected over five years (2010–2012, 2015–2016) at 86 stations (N = 1, 017 samples, 10–270 m depth), comprising 1,327 species with 45 combinations of functional traits. The variation in species composition and functional trait assemblages were both consistent with the occurrence of three separate regions in the Yucatan Peninsula (West Yucatan, Mid-Yucatan and Western Caribbean). This regional configuration was consistent with changes in assemblage structure and depth zonation as well as temporal variation. Along with spatial and temporal variation, diversity diminished with depth and different regions exhibited contrasting patterns in this regard. Our results suggest that the spatial and temporal variation of soft-bottom macrofauna at YCS demonstrate the complex organization of a carbonate shelf encompassing different regions, which may represent transitional regions between the Caribbean and the GoM.

Submarine canyons support distinct macrofaunal assemblages on the deep SE Brazil margin

Submarine canyons are common topographic features of continental margins where increased organic matter trapping and complex topography may enhance the abundance of benthic assemblages. This heterogeneity may result in differences in the composition of benthic assemblages and their diversity between canyon and nearby slope sediments. Here we studied and compared benthic macrofaunal assemblages of four submarine canyons and nearby slope transects (150–1300 m depth) on the E-SE Brazil margin (19–23 oS) along the Espírito Santo (ESB) and Campos Basins (CB). We asked if these submarine canyons would increase sediment total organic carbon (TOC) content and thus support higher abundances, lower diversity and dissimilar composition of macrofaunal benthic organisms if compared to open slope stations at similar depths. In general, we found limited support for a higher sediment TOC or macrofaunal abundances in canyons compared to slopes, although a steeper unimodal curve of TOC with depth in canyons was evidenced. Significant differences in sediment grain size and macrofaunal assemblages also occurred at spatial scales of basins, water depth and interactions between depth and environment (slope/canyon); highlighting the importance of intra-canyon heterogeneity processes. However, canyons and slope environments had significant differences in the structure of macrofaunal assemblages that were partially explained by water depth, TOC and mean grain size. The spatial heterogeneity within canyons and a variable proximity to continental runoff lead to a high dissimilarity of upper slope canyon assemblages indicating that these environments should be included in marine spatial conservation planning along Brazil’s EEZ in view of increasing offshore deep-sea exploration.

Effects of Tropical Saltmarsh Patches on the Structure of Benthic Macrofaunal Assemblages

Habitat complexity can affect assemblage abundance, richness and composition by providing resources and mediating ecological interactions for an array of organisms in many ecosystems. Temperate saltmarshes are well studied, but little is known about tropical saltmarshes. Here we tested if the presence of saltmarsh patches would increase macrofaunal richness, abundance and influence the structure of macrofaunal assemblages when compared to non-vegetated tidal flats. Macrofaunal abundance was higher in vegetated than in non-vegetated areas, but richness did not differ among areas. Macrofaunal assemblage structure was significantly different among areas and composition differed mainly due to greater abundances of epifaunal species in vegetated areas. Within saltmarshes, the macrofaunal composition generally had greater variability than in non-vegetated areas, likely due to greater habitat complexity generating different environmental conditions. Additionally, megalopa and juvenile individuals of Leptuca leptodactyla were more abundant in vegetated areas indicating that tropical saltmarshes may have an important role as a nursery ground for fiddler crabs. This study increased knowledge of tropical saltmarsh patterns and suggests that further research should test the ecological roles of tropical saltmarshes, such as a nursery.

Identifying benthic macrofaunal assemblages and indicator taxa of intertidal boulder fields in the south of the Bay of Biscay (northern Basque coast). A framework for future monitoring

The French southern marine subregion of the Bay of Biscay presents local environmental features explaining the presence of specific communities in remarkable habitats. The aim of the study is, for the first time, to assess benthic macrofaunal assemblages and to identify indicator species of each assemblage within intertidal boulder field habitats in this marine subregion.Mobile boulders were sampled with a stratified random sampling design in upper and lower midlittoral zones in March–June 2015. Sessile (in percentage cover) and mobile macrofauna (in abundance) communities were identified and counted within 0.1 m2 quadrats. Ecological function and precision between the two groups were found dissimilar thus species richness, abundance, macrofauna distribution and indicator species/taxa of sessile and mobile macrofauna were analyzed separately. 78 species/taxa of macrofauna were recorded. A restricted list of 12 singletons (8 for mobile and 4 for sessile macrofauna) and 33 combinations of species/taxa were identified as significant indicators of each assemblage. Species ecological features (food webs, signs of disturbance, alien species, biogeographical range limit) were also considered as additional selection criteria. Therefore, species with a high ecological interest but not considered statistically as valid indicators were also highlighted.Thus, this work constitutes a framework for future monitoring of the Basque intertidal rocky shore and could be used as an alternative to sampling the entire biodiversity. It also meets the MSFD requirements (e.g. take into account marine subregion specificities; integrate the metric “macrofauna” and supports several descriptors as the D1 “Biodiversity” and D6 “Seafloor integrity”).

Effects of sub-seabed CO2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages

The continued rise in atmospheric carbon dioxide (CO2) levels is driving climate change and temperature shifts at a global scale. CO2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO2), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies.

Broad scale variation in seagrass benthic macrofaunal assemblages along the coast of Japan

Broad scale studies in seagrass benthic macrofauna are important for future regional marine conservation. We examined spatial variation in the community structure of seagrass-associated benthic macroinvertebrates collected by sediment coring in 2010 at six seagrass sites of Japan covering the latitudinal range of 24°–43°N. Total species richness and ES(50) at site level did not show clear site variations and relationship with latitude. At core level, site variations of mean species richness, ES(50), Simpson diversity and abundance showed inconsistent pattern, but with more cases of statistically significant association with latitude. Variations were generally influenced by the seagrass species, often among subtropical species, among temperate Zostera species, and between Zostera and subtropical species. Finally, the community composition differed significantly across all sites and community similarity decreased rapidly with geographic distance, with only 5% similarity retained at the distance of 400 km. The dissimilarity among sites was higher with the similar distance compared to other types of coastal communities such as rocky intertidal assemblages, which is associated with minor occurrence of species with broad distributional range.

Mangrove clearing impacts on macrofaunal assemblages and benthic food webs in a tropical estuary

Despite over 21,000ha of mangrove forests being removed per year in Brazil, ecological changes following mangrove deforestation have been overlooked. Here we evaluated changes in benthic macrofaunal assemblages and food-webs at a mangrove removal and natural sites in a tropical estuary in Eastern Brazil. The impacted site had coarser sediment particle sizes suggesting significant changes in sedimentation processes after forest clearing. Spatial differences in macrofaunal abundance, biomass and diversity were not directly associated with the removal of mangrove forests, supporting recolonization of impacted areas by estuarine fauna. However, benthic assemblage composition, infaunal δ13C signatures and food-web diversity markedly differed at the impacted site being strongly related to sedimentary changes. The loss of infaunal trophic diversity that followed mangrove removal suggests that large-scale forest clearing may impact estuarine food webs, with potential consequences to nearby coastal ecosystems given the high clearing rate of mangrove forests in Brazil.

New records of Lumbrineridae (Annelida: Polychaeta) in the Mediterranean biogeographic province, with an updated taxonomic key

The present study is a part of a larger project aiming to characterise the benthic macrofaunal assemblages from the Gulf of Milazzo (Southern Tyrrhenian Sea, Central Mediterranean). Forty-eight samples from 16 sites were collected during the summer of 2010 by means of van Veen grab (0.1 m2) at 20 and 50 m depths to characterise taxonomically, ecologically and biogeographically the present species of Lumbrineridae. Sandy-silt mixed sediments characterised the study area. Abyssoninoe hibernica and Lumbrineris luciliae are newly recorded for the Mediterranean Sea, and Gallardoneris iberica, Lumbrineris geldiayi and Lumbrineris lusitanica are new records for the Central Mediterranean Sea. Therefore, a total of 29 species of Lumbrineridae are currently present and recognised on Mediterranean coasts. Additionally, we provide an updated key to the Mediterranean species of the family.

Bathymetric and regional changes in benthic macrofaunal assemblages on the deep Eastern Brazilian margin, SW Atlantic

Deep-sea continental slopes have valuable mineral and biological resources in close proximity to diverse, undersampled and fragile marine benthic ecosystems. The eastern Brazilian Continental Margin (19.01°S to 21.06°S, 37.88°W to 40.22°W) is an important economic region for both fishing and oil industries, but is poorly understood with respect to the structure of the soft-sediment benthic fauna, their regional distribution and their bathymetric patterns. To identify spatial and temporal patterns of benthic macrofaunal assemblages on the slope (400 to 3000m), the Espirito Santo Basin Assessment Project (AMBES, coordinated by Cenpes-Petrobras) sampled 42 stations across the Brazilian Eastern Slope during both Summer 2012 and Winter 2013. We found a significant decrease in macrofaunal abundance at the 400m isobath along the slope near the northern region of the Espirito Santo Basin, suggesting benthic responses to upwelling events towards the south in Campos Basin and southern Espirito Santo Basin. The taxonomic diversity and assemblage composition also changed significantly across depth zones with mid-slope peaks of diversity at 1000–1300m. In general, macrofaunal assemblages were strongly related to slope depth, suggesting a strong influence of productivity gradients and water mass distribution on this oligotrophic margin. Sediment grain size was marginally important to macrofaunal composition on the upper slope. In general, macrofaunal assemblages on the slope of Espirito Santo Basin are similar to other areas of the SE Brazilian margin, but regional changes in response to productivity and depth need to be considered for management strategies in the face of increasing economic activities off-shore.

Checklist of Intertidal Benthic Macrofauna of a Brackish Water Coastal Lagoon on East Coast of India: The Chilika Lake

During the present inventory related to benthic macrofaunal assemblage in the intertidal region of outer channel area encompassing the period from 2007 to 2010, recorded a total of 135 species from 8 phyla. The phylum annelid became the major group having 46 species followed by mollusca with 41 species. The class polychaeta emerged as the dominant group with 39 species followed by the class bivalve having 21 species. Some of the taxa substantiated during the study period predominantly occurred throughout the study period were those of Spongilla alba , Membranipora bengalensis , Capitella capitata , Minuspio cirrifera , Heromastus filliformis , Grandidierella taihuensis , Niphargus chilkensis , Quadrimaera incerta , Ampithoe ramondi , Mesopodopsis orientalis , Ctenapseudes chilkensis , Alpheus edwardsii , Uca sp., Diogenes custos , Remipes sp., Amphibalanus Amphitrite , Chironomus , Lepas (Anatifa) anatifera , Meretrix meretrix , Mactra stultorum , Brachidontes striatulus , Solen annandalei , Crassostrea cuttackensis , Bufonaria echinata , Epitonium clathrus Nassarious stolatus , Umbonium vestiarium , Astropecten bengalensis , Ichthyocampus carce etc. One rare species namely Hippocampus fuscus was recorded during the present study from the sea grass meadows. Among environmental parameters salinity and chlorophyll a appeared as the major factor controlling the intertidal macrobenthos of outer channel area significantly . Strong seasonal heterogeneity was also observed in the environmental parameters like salinity, DO etc together with number of macrobenthos taxa. Among significant observation, higher number of macrobenthos taxa in summer season as compared to monsoon season in both years of study was evidenced . Since many of the newly occurring taxa in the lagoon premises were of typical marine forms observed during 2009-10 study year, hence the present study strongly supported that the opening of a new lagoon inlet have positive impact on benthic macrofaunal assemblage of the intertidal region.

Analysis of sampling methods of estuarine benthic macrofaunal assemblages: sampling gear, mesh size, and taxonomic resolution

Benthic estuarine studies are usually very time-consuming. Therefore, it is critical to optimize procedures ensuring efficiency with low cost. The present study aimed to assess the cost/benefit ratio of different sampling procedures and analyze its effect on the description of spatial pattern of benthic assemblages along an estuarine gradient. Six methodological combinations (sampling gear: van Veen grab or corer; mesh sizes: 0.5, 0.7 or 1.0 mm) were applied at 11 sampling stations. The van Veen grab captured 1,219 individuals and 59 taxa, while the corer captured 967 individuals and 53 taxa. Increasing the mesh size caused a decrease in the number of specimens retained and in the time needed to sort samples. However, no significant differences were observed among the analyzed sampling methods (sampling gear and mesh size). Spearman rank correlation coefficient showed that there was little ‘information loss’ when aggregating data to genus and family taxonomic levels. A cost/benefit index is introduced which reveals that the van Veen grab + 1.0 mm sieve + family level was the best combination to achieve the best balance between cost and precision of the results. However, choice of sampling procedure must consider estuary characteristics, target fauna, and research infrastructure, resources and objectives.

Benthic macrofaunal assemblages in multispecific seagrass meadows of the southern Philippines: Variation among vegetation dominated by different seagrass species

Although the influence of seagrasses on the diversity and abundance of associated fauna is generally well understood, the effects of seagrass specific identity are not. To determine whether benthic epifaunal and infaunal assemblage patterns vary by the identity of dominant seagrass species in shallow water meadows, we compared quantitative measures of faunal species richness, abundance, and assemblage structure among beds dominated by Cymodocea rotundata, Enhalus acoroides, and Thalassia hemprichii; the study site was at Lopez Jaena, Misamis Occidental Province in the southern Philippines. The Cymodocea-dominated vegetation had higher seagrass shoot density and lower seagrass biomass than those dominated by Enhalus and Thalassia. Across vegetation types, we encountered 30 and 15 species of epifauna and infauna at average densities of 1.73 and 0.82 animals/core (0.0314m2), respectively. Neither densities and species richnesses of epifauna and infauna nor species composition varied significantly by vegetation type. Multivariate analyses of macrofaunal assemblage structure and abiotic/biotic environmental factors demonstrated that seagrass aboveground biomass explained a significant proportion of the multivariate variation in epifaunal species composition (39%); none of the potential explanatory variables was related to variation in ecological parameters of the infauna. Thus, seagrass specific identity is not a good predictor of either macrofaunal abundance or diversity patterns. Although the ecological parameters of the benthic macrofauna may be influenced by seagrass biomass and structure, responses differ between epifauna and infauna.

Changes in benthic macrofaunal assemblages in relation to bottom trawling in Cuddalore and Parangipettai coastal waters, Southeast coast of India

Variations in benthic biodiversity owing to bottom trawling were studied in the inshore waters of Parangipettai (Lat.11°24′N; Long. 79°464′E) and Cuddalore (Lat. 11°434′N; Long. 79°494′E), India from February 2009 to January 2010. Four stations each in Parangipettai and Cuddalore were prepared and established. A total of 114 species in Parangipettai and 101 in Cuddalore were found. The population density showed a maximum (10,387 no. m-2) in Parangipettai in the sample collected before trawling and a minimum (40no. m−2) in Cuddalore in the samples collected after trawling. Among the faunal groups, polychaetes topped the list followed by other groups of organisms both in the samples before and after trawling. Shannon diversity varied from 2.23 to 4.24, 1.85 to 3.45; Margalef richness from 3.2 to 5.9, 2.57 to 4.25; Pielou’s evenness varied from 0.79 to 0.94, 0.81 to 0.88 in the samples collected before and after trawling respectively in Parangipettai. In Cuddalore waters, Shannon diversity ranged from 2.15 to 3.85, 1.92 to 3.15; Margalef richness from 2.95 to 5.2, 2.24 to 3.95 and Pielou’s evenness index from 0.84 to 0.91, 0.79 to 0.82 in the samples before and after trawling respectively. Multivariate methods also showed distinct variations in terms of species composition and abundance between regions and samples.

Impacts of the invasive grass Spartina anglica on benthic macrofaunal assemblages in a temperate Australian saltmarsh

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 464:107-120 (2012) - DOI: https://doi.org/10.3354/meps09826 Impacts of the invasive grass Spartina anglica on benthic macrofaunal assemblages in a temperate Australian saltmarsh Justin Cutajar, Jeff Shimeta*, Dayanthi Nugegoda School of Applied Sciences, RMIT University, Melbourne, Victoria 3083, Australia *Email: jeff.shimeta@rmit.edu.au ABSTRACT: Reported impacts of the invasive saltmarsh grass Spartina anglica on benthic macrofaunal assemblages around the world vary considerably, and there is little understanding of the reasons for this variation. We compared macrofaunal assemblages and sediment characteristics among patches of S. anglica and adjacent uninvaded habitats (bare mudflat and native saltmarsh) in southeastern Australia. Invaded patches showed reduced species richness (by 50%) and diversity compared to both uninvaded habitats. Macrofaunal abundance in S. anglica patches was also lower than in native marsh (by 60%), but not different from mudflat. There were no differences in biomass among habitats. Ordination clearly separated the species assemblage of invaded patches from uninvaded habitats, suggesting a unique community in the Spartina habitat. Molluscs and crustaceans were the most depleted in S. anglica patches, while the polychaete Nephtys australiensis was enhanced. Infauna and epifauna were both depleted in S. anglica, although the mechanisms for these impacts should differ. Burrowing by infauna in S. anglica patches was likely impeded by dense roots and rhizomes, because the below-ground plant biomass was 72% greater than in native saltmarsh. Epifauna were likely depleted in S. anglica patches due to shading-induced inhibition of microphytobenthos growth, consistent with measured reductions of porewater salinity and increased mud content. Salinity and mud content were the sediment parameters that correlated most strongly with macrofaunal assemblage composition. These results, combined with a synthesis of published S. anglica impacts, suggest predictions of when S. anglica facilitates or inhibits macrofauna, considering infauna and epifauna separately. KEY WORDS: Spartina anglica · Invasive species · Cordgrass · Macrofauna · Saltmarsh · Estuary · Australia Full text in pdf format PreviousNextCite this article as: Cutajar J, Shimeta J, Nugegoda D (2012) Impacts of the invasive grass Spartina anglica on benthic macrofaunal assemblages in a temperate Australian saltmarsh. Mar Ecol Prog Ser 464:107-120. https://doi.org/10.3354/meps09826 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 464. Online publication date: September 19, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Habitat‐related benthic macrofaunal assemblages of bays and estuaries of the western United States

Data from 7 coastwide and regional benthic surveys were combined and used to assess the number and distribution of estuarine benthic macrofaunal assemblages of the western United States. Q-mode cluster analysis was applied to 714 samples and site groupings were tested for differences in 4 habitat factors (latitude, salinity, sediment grain size, and depth). Eight macrofaunal assemblages, structured primarily by latitude, salinity, and sediment grain size, were identified: (A) Puget Sound fine sediment, (B) Puget Sound coarse sediment, (C) southern California marine bays, (D) polyhaline central San Francisco Bay, (E) shallow estuaries and wetlands, (F) saline very coarse sediment, (G) mesohaline San Francisco Bay, and (H) limnetic and oligohaline. The Puget Sound, southern California, and San Francisco Bay assemblages were geographically distinct, while Assemblages E, F and H were distributed widely along the entire coast. A second Q-mode cluster analysis was conducted after adding replicate samples that were available from some of the sites and temporal replicates that were available for sites that were sampled in successive years. Variabilities due to small spatial scale habitat heterogeneity and temporal change were both low in Puget Sound, but temporal variability was high in the San Francisco estuary where large fluctuations in freshwater inputs and salinity among years leads to spatial relocation of the assemblages.

Benthic macrofaunal assemblages of the San Francisco Estuary and Delta, USA

The spatial and temporal distribution of macrobenthic assemblages in the San Francisco Estuary and Sacramento-San Joaquin River Delta were identified using hierarchical cluster analysis of 501 samples collected between 1994 and 2008. Five benthic assemblages were identified that were distributed primarily along the salinity gradient: (1) a polyhaline assemblage that inhabits the Central Bay, (2) a mesohaline assemblage that inhabits South Bay and San Pablo Bay, (3) a low-diversity oligohaline assemblage primarily in Suisun Bay, (4) a low-diversity sand assemblage that occurs at various locations throughout the Estuary, and (5) a tidal freshwater assemblage in the Delta. Most sites were classified within the same assemblage in different seasons and years, but a few sites switched assemblage designations in response to seasonal changes in salinity from freshwater inflows.