Miliammina Fusca Research Articles

Foraminifera Associated With Swirled Spartina Patens Beds on Perched Marshes Along the Rocky Coastline of Lunenburg County, Nova Scotia

ABSTRACT Perched marshes in Lunenburg County differ in exposure to prevailing waves (from most to least exposed: Crescent Beach, Blue Rocks, Feltzen South). We sampled the middle marsh, recording replicates’ dried masses. In picking stage 1 (PS1), the first 400 foraminifera, whether agglutinated or calcareous-walled, were picked and identified. From these data we calculated the Shannon Function H and compared the between-locale signals of benthic foraminifera using a relative-dominance index, ACW, for agglutinated and calcareous-walled foraminifera. Crescent Beach was a distinct locale with much medium-grained quartz sand and abundant allochthonous calcareous foraminifera (hence ACW < 1). The other sites’ ACWs ranged from ∼50–100. There was a significant negative ACW:residue mass correlation. In picking stage 2 (PS2), the remaining agglutinated foraminifera were picked. The Feltzen South perched marsh yielded only Miliammina fusca, perhaps reflecting high %N and %C. Meanwhile, Trochammina inflata was abundant at Crescent Beach and Blue Rocks.

Distribution and ecology of benthic foraminifera in the Santoña estuary, Spain

The living and dead assemblages in the Santoña estuary were studied seasonally in order to determine the distribution and abundance of the benthic foraminifera in this area. Samples were collected from Winter 1983 to summer 1985 to document the seasonal variation of the faunas and various ecological factors in the intertidal zone. Salinity is thought to be the main control of the living assemblages and two different biofacies characterising the upper and lower areas have been defined. Ammonia beccarii and Haynesina germanica are the most dominant forms throughout the estuary with Miliammina fusca as co-dominant in the upper estuary and Quinqueloculina seminulum as co-dominant in the lower estuary. The dominant living species are also dominant in the dead assemblages but in the latter the agglutinated indigenous component is much more abundant. This compositional difference is thought to be caused by production rates and change in the environmental conditions within the estuary. The living and dead assemblages have been analysed and compared using the Fisher a diversity index, Triangular plot of wall types and Sanders similarity index.

The response of foraminifera to rapid sea-level rise from tidal restoration of Ni-les'tun marsh, Oregon, U.S.A

Foraminifera preserved in saltmarshes are widely used to reconstruct relative sea-level change (RSL), and inferred from this, coseismic vertical coastal motions following an earthquake. However, how quickly foraminifera respond to rapid changes in RSL is poorly understood. Here, we present a six-year foraminiferal study of the tidal restoration of Ni-les'tun marsh and a comparison of modern and fossil assemblages. We installed eight stations on the marsh and sampled these stations for live foraminifera prior to and during the first six years after tidal restoration (2011–2017), and we extruded one short core at station 1 in 2016. At stations 1 to 7, tidal flat/low marsh assemblages, dominated by Miliammina fusca, colonized 10 months to 2.5 years after tidal restoration. At station 8, the first living mixed assemblage of foraminifera, dominated by Haplophragmoides wilberti, was found 2 years after tidal restoration. Our observations suggest that M. fusca, and to some extent H. wilberti, are opportunistic species (r-strategists), able to increase their standing crop rapidly after invading a new habitat (to up to ~3600 specimens per 10 cm3 sediment volume). Potential causes for the delay in foraminifera colonization include their reproductive cycle and/or limited food availability due to the slow response of the vegetation community and soil development to tidal restoration. However, the similarity among assemblages and concentrations of agglutinated foraminifera between the fossil and modern sediments, indicate that post-depositional taphonomic processes have minimal influence when incorporated in the stratigraphic record. Although foraminifera have shown a delayed response to tidal restoration in the Ni-les'tun marsh, the similarities between the modern and fossil assemblages indicate that the delayed response of foraminifera to tidal restoration is undetectable in study areas with low sedimentation rates (in this case 3.3 mm/yr) after tidal restoration. In the case of high post-earthquake sedimentation rates, sampling a few cm higher rather than immediately above an earthquake contact could avoid uncertainties of coseismic vertical motions when foraminifera have a delayed colonization.

Subsurface and Infaunal Foraminifera of Kemaman-Chukai Mangrove Swamps, East Coast Peninsular Malaysia

This study analysed the distribution and abundance of dead and live (Rose Bengal stained) infaunal foraminifera from three short cores taken at three locations in the mangrove swamps of Kemaman-Chukai, Terengganu, Malaysia. Eighteen agglutinated taxa were recorded in assemblages dominated by Arenoparrella mexicana, Haplophragmoides wilberti and Miliammina fusca; and of these, only two taxa were recorded as live. The distribution of subsurface and infaunal foraminifera varied from core to core, as did their depth of occurrence. Core 1 (seaward core) was dominated by sandy deposits, relatively high salinity (32 ppt), and extensive crab mounds, displayed very low numbers of dead foraminifera inconsistently throughout the core, while no infaunal foraminifera were observed, indicating intense bioturbation by mangrove crabs. In Core 2 (middle core), even though the numbers of live foraminifera decreased down-core, the number of dead or subsurface foraminifera were inconsistent, indicating taphonomic loss of the tests. Core 3 (landward core) however, displayed ideal foraminiferal distribution patterns required in the palaeo sea-level reconstruction (with less taphonomic loss and decreasing number of infaunal foraminifera downcore). Because of the similarity displayed in the foraminiferal assemblages in the 0–1 cm and 10–11 cm intervals, the surface sample (0–1 cm) should be an acceptable basis for down-core reconstructions in this study. Live (Rose Bengal stained) infaunal foraminifera, though observed at 40–41 cm depth, are not considered abundant enough to influence the dead assemblage in the subsurface sediment and its applicability for palaeoenvironmental and sea-level reconstructions. Therefore, it is possible for palaeo sea-level to be reconstructed based on foraminiferal assemblages preserved in the Kemaman-Chukai mangrove swamps.

Environmental Controls on the Distribution of Modern Benthic Foraminifera in the Florida Everglades and Their Use as Paleoenvironmental Indicators

ABSTRACT This study examined the environmental factors that control the distribution of modern foraminiferal assemblages in the Everglades in order to provide baseline data for a paleoenvironmental study. Total assemblages from the surface 2 cm of 30 sites across the marsh and mangrove environments of southwest Florida were investigated. Eight environmental variables, including average salinity, salinity range, pH, total phosphorus, temperature, and dissolved oxygen, and total organic carbon and total inorganic carbon measured on bulk sediments, as well as the elevation and distance from the coastline were determined for each of the 30 sampling locations. In total, 82 species were identified, the majority of which were calcareous. Diversity decreases, dominance increases, and agglutinated taxa increase from the coastline inland. Rotaliina are equally abundant across the intertidal environment, whereas Miliolina are common near the coast and in lagoons or inland lakes. The most important factor controlling foraminiferal distribution is total organic carbon, followed by total inorganic carbon, distance from coastline, total phosphorus, and salinity. Jadammina macrescens and Miliammina fusca indicate lower salinities (<15 psu). Good indicators for higher salinities are Haplophragmoides wilberti (10–20 psu) and Arenoparrella mexicana (10–20 psu and 28–30 psu). Ammonia spp. prefer salinities >15 psu and Elphidium spp. >20 psu. Ammonia tepida, Helenina anderseni, Trochammina inflata, and A. mexicana prefer organic-rich sediments. Thus, the benthic foraminifera from Everglades sediments are excellent salinity proxies and can be used to determine the history of habitat change in this area as well as to assess past trends in the rate of sea level rise.

Development of a Training Set of Contemporary Salt-Marsh Foraminifera for Late Holocene Sea- Level Reconstructions in southeastern Australia

We collected contemporary foraminiferal training sets from two salt marshes to enable more precise and accurate proxy historical sea-level reconstructions from southeastern Australia. Combined with an existing training set from Tasmania, this new regional set consists of 112 samples and 16 species of foraminifera, of which 13 are agglutinated. Cluster analyses group the regional training set into a high–elevation cluster, dominated by Trochamminita salsa, a mid–elevation cluster, dominated by Entzia macrescens and Trochammina inflata, and a mid–low elevation cluster dominated by Miliammina fusca and tidal-flat species. We develop transfer functions using local and regional training sets and assess their performance. Our resulting site-specific and chosen regional models are capable of predicting sea level with decimetre-scale precision (95% confidence intervals of 0.12–0.22 m). These results are comparable to other examples from around the world. When developing regional training sets, we advocate that the similarity in the environmental settings (particularly salinity) should be assessed as an alternative way of grouping sites, rather than simply using spatial proximity. We compare our findings with global results and conclude that salt marshes along microtidal coasts yield models with the lowest vertical uncertainties. Studies with the lowest uncertainties are located in the western Pacific and the western Atlantic, whereas those from the eastern Atlantic generally have larger tidal ranges and carry larger vertical uncertainties. Our models expand the existing region available for sea-level reconstruction and can be used to generate new late Holocene sea-level reconstructions across southeastern Australia.

Inter-specific and inter-individual trait variability matter in surface sediment reworking rates of intertidal benthic foraminifera

Although benthic foraminifera are an important component of meiofauna and contribute to carbonate production and carbon/nitrogen cycles, their role in bioturbation processes remains poorly known. Five dominant intertidal benthic foraminiferal species were recently classified into functional bioturbator groups according to their sediment reworking mode and intensity. Our study aimed at identifying potential drivers (i.e. size and/or travelled distance) of species-specific surface sediment reworking rate. The travelled distance and surface sediment reworking rate of Haynesina germanica, Cribroelphidium williamsoni, Ammonia tepida, Quinqueloculina seminulum and Miliammina fusca were assessed through image analysis. Our results show that the surface sediment reworking performed by these species is not size-dependent, but dependent on their motility traits through interspecific differences in the travelled distance. Smaller species (i.e. Quinqueloculina seminulum and Haynesina germanica) contributed more to surface sediment reworking than larger ones (i.e. Ammonia tepida, Cribroelphidium williamsoni and Miliammina fusca). These observations stress the critical role of motion behaviour in surface sediment reworking processes by intertidal foraminifera. Finally, we stress that the high inter-individual variability observed in conspecific motion behaviour may be important to decipher the role of foraminifera in sediment bioturbation. Noticeably, the species characterized by a strong inter-individual variability are also the species that have the highest surface sediment reworking rates. This last observation may inform on the species-specific phenotypic plasticity and, therefore, the potential for the functional role of these species to be maintained in their natural environment. This is particularly relevant in an era of global change where ecosystem balance is increasingly threatened by various stressors such as heat-waves, ocean acidification and pollution.

Contemporary distribution of benthic foraminiferal assemblages in coastal wetlands of south-eastern Australia

Benthic foraminifera identified from the upper intertidal zone of coastal mangrove and saltmarsh wetlands of south-eastern Australia exhibit spatial zonation that varies with elevation and corresponds to position in the tidal frame. This study describes relationships between benthic foraminiferal assemblages and environmental variables, such as wetland elevation, pore-water salinity, substrate organic matter content and sediment grainsize. Agglutinated taxa dominated higher in the tidal frame, whereas calcareous taxa increased in both relative abundance and diversity lower in the tidal frame. Species composition varied within and between study sites, reflecting local differences in other environmental variables. Three major spatial clusters were identified in the upper intertidal zone from a dataset consisting of 111 contemporary samples: a high-to mid-elevation assemblage consisting of differing abundances of Entzia macrescens and Trochammina inflata; a mid-elevation assemblage comprised of Arenoparrella mexicana in association with Trochammina inflata and Quinqueloculina seminula; and mid-to low-elevation assemblage characterised by Cribroelphidium excavatum, Quinqueloculina seminula, Ammobaculites spp. and Miliammina fusca. Multivariate analysis correlated foraminiferal assemblages with environmental variables showing that foraminiferal distribution in the region is constrained primarily by wetland elevation, but also by pore-water salinity. Foraminiferal assemblages derived from cluster analysis correlated with vegetation zones, implying that both foraminifera and vegetation are influenced by elevation and salinity. This paper seeks to demonstrate that the consistency in spatial zonation of assemblages provides greater confidence that contemporary distribution of foraminiferal assemblages can assist with the interpretation of past depositional conditions and palaeo-environmental reconstructions, providing insights into the evolution of coastal wetlands of south-eastern Australia over the Holocene.

BENTHIC FORAMINIFERAL BIOCOENOSES IN THE ESTUARINE REGIMES OF GOA

Benthic Foraminifera are highly responsive to subtle changes in the estuarine environment. Keeping this in view, a qualitative analysis of living benthic Foraminifera was made of the samples collected from the Mandovi—Zuari estuaries and the connecting long and narrow Cumbarjua canal of Goa. The lower reaches of the rivers are paved with a substrate consisting mostly of sand while it is silty—sand in the upper estuarine zones and clayey in the canal zone. The living Foraminifera are abundant in the upper estuarine zones of the rivers and the Cumbarjua canal junction zones, and characterised by the Ammonia—Trochammina suite with Miliammina fusca; while the canal zone is enriched by agglutinated formes. The Ammonia—Elphidium suite dominates the lower estuarine zones indicating a typical marine environment. The high organic matter content particularly in the Canal Zone is due to the inflow of pollutan ts from the nearby pesticide factory and the constant contaminating discharge of navigating barges and other mechanised boats of the fishing industry. Ammonia sp. and its variants and other agglutinated species become dominant here. The decline in calcareous species and thinning of the dead tests leading to their eventual destruction may be attributed to their susceptibility to acidity in the waters.

Salt-Marsh Foraminiferal Distributions from Mainland Northern Georgia, USA: An Assessment of Their Viability for Sea-Level Studies

We investigated foraminiferal distributions from two salt-marsh sites at Thunderbolt and Georgetown, in mainland northern Georgia, U.S. Atlantic coast. We analyzed modern epifaunal foraminiferal assemblages across multiple transects consisting of 54 surface samples. Multivariate statistical analysis (Partitioning Around Medoids and Detrended Correspondence Analysis) revealed that dead foraminiferal assemblages are divided into three faunal zones, which are elevation-dependent and site-specific. At Thunderbolt, an intermediate salinity marsh (17‰), high marsh assemblages are dominated by Haplophragmoides spp. with an elevational range of 1.19 to 1.68 m mean tide level (MTL) between Mean Higher High Water (MHHW) to Highest Astronomical Tide (HAT). Low marsh assemblages are dominated by Miliammina fusca and Ammobaculites spp. with an elevational range of – 0.05 to 1.14 m MTL (between MTL and MHHW). At Georgetown, a low salinity marsh (6‰), the assemblages are dominated by Ammoastuta inepta with an elevational range of 0.43 to 1.16 m MTL (between MTL and MHHW). We also enumerated living infaunal foraminiferal populations from six 50-cm sediment cores from the two salt marshes to assess implications for interpretations of sea-level change. Peak concentrations of living foraminiferal populations occur in the upper 1-cm surface sediment in five of the six cores. An exception was observed in high marsh settings of Thunderbolt, where Haplophragmoides spp. and Arenoparrella mexicana were observed living down to 40 cm depth and both the live and dead abundance peaked (32 and 520 specimens per 10 cc respectively) between depths of 15–35 cm in the core. The dominant infaunal species were similar to those observed in modern surface samples, and the total number of infaunal foraminifera was typically less than 15% compared to the total number of dead specimens in the surface samples. Finally, we com­pared the down-core patterns of living and dead foraminiferal abundance that suggest that 90% of the tests were removed within the upper 10 cm of sediment in most cores. This may be due to taphonomic alteration from bioturbation and/or microbial processes. Selective preservation between resistant species such as A. mexicana and fragile species like M. fusca and Ammobaculites spp. can change the subsurface foraminiferal assemblage. This has the potential to cause errors in sea-level reconstructions using foraminiferal assemblage from low marsh sediments. This study highlights the modern vertical distribution of salt-marsh foraminifera in mainland northern Georgia and their potential as modern analogues for fos­sil counterparts in reconstructing sea-level changes. Taphonomic processes may cause the absence of foraminiferal tests or differences between modern and fossil assemblages, which could be problematic when performing RSL reconstructions in low marsh environment. Publisher's note: a correction article relating to this paper has been published and can be found at http://doi.org/10.5334/oq.91

Saltmarsh foraminifera in the subarctic White Sea: Thrive in summer, endure in winter

Abundance and diversity of intertidal benthic foraminifera decreases towards the poles. Well studied in the temperate zone, saltmarsh foraminiferal assemblages have only recently received attention at higher latitudes. We report modern foraminifera, including the taxonomy, abundance, and zonation, from a pristine saltmarsh in the subarctic White Sea, northern Europe. We sampled 10 stations (surface sediment, two replicates) from two high-tide flats covered with lush halophytic plants. Nine foraminiferal species found exhibited distinct vertical zonation confined to certain elevation levels. The high marsh assemblage comprised arenaceous Balticammina pseudomacrescens, Trochammina inflata, Jadammina macrescens, and monothalamous Ovammina opaca. This is the northernmost location where the first two species have been encountered alive. The low marsh assemblage was dominated by Miliammina fusca and Elphidium williamsoni. Summer abundances of live foraminifera were surprisingly higher than on other subarctic saltmarshes studied, mostly 100–500 and up to 3000 per 10 cm³. In winter, under a 40 cm of ice, the abundances were only 15–20 ind./10 cm³, but the species richness was the same. Unlike summer specimens of calcareous foraminifera, which are always brightly colored, winter Elphidium williamsoni all had bleak colorless cytoplasm, suggesting they discard kleptoplasts and abandon algal diet. We conclude that the insulating blanket of fast ice, which hardly moves on saltmarshes, prevents elimination of foraminifera in the harshness of winter, whereas the intense continental heating in summer lets them thrive on White-Sea saltmarshes. The composition of foraminiferal assemblages under local climatic conditions may thus deviate substantially from the latitudinal trend.

Mesocosm and Microcosm Experiments On the Feeding of Temperate Salt Marsh Foraminifera

AbstractAgglutinated foraminifera dominate in temperate salt marsh sediment, making them key indicators for monitoring sea level and environmental changes. Little is known about the biology of these benthic foraminifera because of difficulties in distinguishing live from dead specimens in laboratory cultures. We present data from 10 years of laboratory experiments using comparisons of the agglutinant trochamminids Trochammina inflata and Entzia macrescens and the miliolid Miliammina fusca with the calcareous rotalids Helenina anderseni and Elphidium williamsoni. Specimens were taken from a laboratory mesocosm representing Chezzetcook Inlet, a cool-temperate salt marsh in eastern Canada. We determined culture requirements for the agglutinated foraminifera in Petri dishes over 10–12 week periods. Five inexpensive, non-terminal ways of identifying live organisms were developed: spatial movement, detritus-gathering, attachment, clustering, and test opacity. Comparison with rose Bengal staining showed <10% diversion for calcareous species and T. inflata but M. fusca was over-counted by >30%. Terminal chambers of Trochammina inflata were examined by transmission electron microscopy to visualise food consumption and identify food in digestive vacuoles, both in specimens from mesocosm and in culture. Bacteria and unidentified detritus in the vacuoles establish that this agglutinated species is a saprophagous and bacterivorous detritivore. The adhesive secretions by these species apparently help them gather and possibly farm food while being relatively immobile in the sediments. Our observations of movement and feeding orientation in the agglutinants suggest links between form and function that underscore their value as ultra high resolution sea-level proxies. Mesocosm biomass and abundance counts show that foraminifera represent >50% of the meiofaunal biomass, emphasising their importance in the food web and energy-flow dynamics of temperate salt marsh systems.

Distribution of foraminifera from South Shetland Islands (Antarctic): Ecology and taphonomy

The aim of this study was to analyze the distribution of foraminifera of surface sediments from South Shetland Islands (62∘0′ S 58∘0′ W) in relation to physical parameters. Three sites were analyzed: 1) North of South Shetland Island; 2) Deception Island, and 3) Potter Cove. We have identified 21 species, which were distributed in 13 genera, mainly from the Orders Rotaliida and Trochamminida. There was a predominance of calcareous individuals in Shetland Islands — represented by Cibicides refulgens (Montfort) and in Potter Cove, where Globocassidulina subglobosa (Brady) and Globocassidulina rossensis (Kennett) were the main representatives. In Deception Island, the proportion of calcareous individuals was matched by that of agglutinated specimens, represented by Trochammina inflata (Montagu) and Miliammina fusca (Brady). Foraminifers also exhibited different lifestyles, microhabitats, feeding strategies, and taphonomy. A strong correlation between microfauna and physical parameters was observed at the three sites. Assemblage I consisted on Cibicides refulgens, Cibicides aknerianus (d’Orbigny), Melonis affine (Reuss) and Melonis pompilioides (Fichtel and Moll), which were all distributed along the bathymetric gradient and the clay sediments. Assemblage II comprised Trochammina inflata, Miliammina fusca and Cassidulinoides parkerianus (Brady), which were correlated with a higher content of gravel. And assemblage III included individuals of Globocassidulina subglobosa and Globocassidulina sp., both correlated with higher sand content. This work contributes to increasing our knowledge about the distribution of foraminifera in the Antarctic zone, which is a largely understudied region. The new data could be useful for both determining environmental conditions and establishing bioindicators of pollution and anthropogenic activity. In addition, the correlations with climate events might contribute to the development of new tools for monitoring climate variations.

Benthic foraminifers as a proxy of the range of the tidal wave in the Oyambre Estuary (Cantabria, Spain)

Recent benthic foraminifers from the Oyambre estuary (north of Spain) have been studied in order to learn their biological response to drastic anthropic environmental changes that this estuary has undergone within the last centuries. Up to 41 species have been identified and 24 of them showed live specimens during the sampling period. The most abundant species are Ammonia tepida, Balticammina pseudomacrescens, Cribroelphidium williamsoni, Entzia macrescens, Haynesina germanica, Cibicidoides lobatulus, Miliammina fusca and Trochammina inflata. The statistical analysis (cluster and correspondence analysis) has allowed the differentiation of four groups of samples that are characterized by three assemblages that define the following environments: sandy outer estuary with marine influence (C. lobatulus), mid and inner estuary that comprises an euryhaline subtidal environment with silty sediment (A. tepida and H. germanica), intertidal channels with the lowest salinity levels (C. williamsoni), and marshes (B. pseudomacrescens, E. macrescens, M. fusca and T. inflata).The great number of species with agglutinated shells reveals the ongoing draining in mud-flat areas, as well as the establishment of the vegetated high marsh, where the invasive exotic plant Baccharis halimifolia is removing the reed bed ecosystem and filling, blocking and reducing main and secondary channels. As a result, there is hardly any sandy low marsh left, which in other nearby estuaries of Cantabria is delimited by the species M. fusca. Thus, areas with tidal levels between MHWNT (Mean High Water Neap Tide) and MHW (Mean High Waters) are scarce. However, foraminifer species that live in the high marsh above MHW are dominant. Entzia macrescens and T. inflata mark the interval between MHW and MHWST (Mean High Water Spring Tide), while B. pseudomacrescens the one from MHSWST to the barren zone (vegetated high marshes, closest to land).A comparison between the biocoenosis and thanatocoenosis assemblages generally shows a good similarity (Sanders’ index > 60%). The few samples with a low similarity reveal the effect of post-mortem processes, specially decantation, and, to a lesser extent, suspended transport, which once again points to the lack of hydrodynamism in the estuary. The percentage of exotic or allochthonous species that are deposited in this estuary is very low (the average ranges from 13.4% in the mouth to 0.7% in the inner area), which reveals that the Oyambre estuary has a mesotidal character in its mouth, while in the mid and inner area it can be considered a microtidal estuary. All these data expose that the works conducted in order to recover the Oyambre estuary between years 2009 and 2010 seem not to have been successful in restoring the marshes to their original hydrodynamic conditions.

Distribution of Modern Salt-marsh Foraminifera from the Eastern Mississippi Sound, U.s.a.

AbstractThis study documented surface distributions of live and dead foraminiferal assemblages in the low-gradient tidal marshes of the barrier island and estuarine complex of the eastern Mississippi Sound (Grand Bay, Pascagoula River, Fowl River, Dauphin Island). A total of 71,833 specimens representing 38 species were identified from a gradient of different elevation zones across the study area. We identified five live assemblages and nine biofacies for the dead assemblages from estuarine, low marsh, middle marsh, high marsh, and upland transition environments. Although dissolution of calcareous tests was observed in the dead assemblages, characteristic species and abundance patterns dependent on elevation in the intertidal zone were similar between living assemblages and dead biofacies. The assemblages from the eastern Mississippi Sound estuaries were dominated by Ammonia tepida, Cribroelphidium poeyanum, C. excavatum, and Paratrochammina simplissima. The low marshes were dominated by Ammotium salsum, Ammobaculites exiguus, and Miliammina fusca. The dominant species in the middle marshes was Arenoparrella mexicana. The most abundant species in the high marshes was Entzia macrescens. The upland–marsh transition zones were dominated by Trochamminita irregularis and Pseudothurammina limnetis. Canonical correspondence analysis was applied to assess the relationship between a priori defined biofacies and measured environmental data (elevation, grain size, organic matter, and salinity) to test the hypothesis that distribution of foraminiferal assemblages is driven by elevation and hence flooding frequency. Salinity was the second most important explanatory variable of dead assemblages. Riverine freshwater from the Pascagoula River markedly influenced the live and dead assemblages in the Pascagoula River marsh, which was represented by low diversity and densities and dominance by Ammoastuta inepta. The relationship between the measured environmental variables and assemblage distributions can be used in future Mississippi Sound paleo-environmental studies.

Foraminiferal evidence of basin submergence in part of Sundarban mangrove delta, India

Sundarban is a largest mangrove forest delta developed along the NE-SW direction covering parts of India and Bangladesh. Little work has been done on Indian part of Sundarban in respect of heterogeneity in channel morphology which could be mostly due to the effect of tilting and basin subsidence. These changes might have played a major role on development of high marshes, which offers a congenial environment for survival of Haplophragmoides wilberti, Jadammina macrescens, Trochammina inflata, and Miliammina fusca. These marsh benthonic foraminiferal assemblages provide a direct evidence of recent past sea level changes. To establish the depositional pattern and their effects rendered by merciless changing environment, 11 pit sections have been excavated along three E-W transects from Indian Sundarban. Depth of these pit sections varies from 2 to 3 m. Generally, top 20 cm sediment (in pit section W-1 to W-11) deposited under the intertidal environment, as indicated by the presence of Ammonia tepida. However, sediment below 20 cm in some of the pit sections (W-3 and W-5) exhibits fresh water signatures as indicated by the presence of Charophytes algae. In other pit sections (W-1, W-2, W-6, W-7, W-8, W-9 and W-11), the intertidal assemblage is noticed just above the upper marshes assemblage and vice versa, signifying that depositional environment is in proximity to the mangrove dominated area as indicated by the presence of marsh benthonic foraminiferal assemblage containing T. inflata, H. wilberti, Haplophragmoides sp., J. macrescens and M. fusca. Bottom sediment in most of the pit sections from south to north have different depositional environment with alternate presence of intertidal to subtidal faunal assemblages. The peculiar presence of intertidal assemblage above the upper marshes assemblages in recent sediment points towards the theory of submergence due to relative rise in the sea level. But the effect of relative sea level rise is not uniform throughout the area because of differential subsidence due to varied rate of sediment supply (0.5 to 3.3 cm/year) and eastward tilting of the basin. Based on the upper marshes benthonic foraminiferal assemblage and radiocarbon age (in W-1 at 100 cm ~ 150 years age), the average subsidence rate as recorded is approximately 0.3 to 0.5 cm/year. Hence, such depositional sequence conjectures that the Indian part of Sundarban is undergoing a phase of submergence concomitant to basin subsidence.

Intertidal foraminifera in the Spartina patens floral zone of the LaHave Estuary, Canada: A baseline for assessing organic pollution remediation

The LaHave Estuary is polluted with domestic waste delivered via straight pipes. These are to be replaced with septic tanks. The impact of this remediation on the wider biotic community will need to be assessed. Intertidal foraminifera are ideal for mitigation assessment in the LaHave and comparable estuaries, estuary banks supporting small beds of intertidal vegetation. This paper provides a baseline for future comparisons of the total LaHave intertidal benthic foraminiferal assemblage and presents a method applicable to other estuaries. Regarding the LaHave Estuary, any biotic change must be viewed against the backdrop of other pollutants like mercury near the town of Bridgewater.Four 10 cm3 replicates (push cores) were taken at four sites along the estuary's eastern bank: Miller Point Peace Park (MPPP, near Bridgewater), Dayspring, Upper LaHave and East LaHave. A fifth replicate was tested for %C and %N. To constrain altitude, the replicates were taken immediately inland of a zone of the marsh grass Spartina alterniflora, typically among swirl-patterned (cowlicked) S. patens.The washed replicates were picked clean of foraminifera, 3821 being recovered. Recovery comprised only (in rank order of abundance) Entzia macrescens, Trochammina inflata and Miliammina fusca. The number per replicate ranged from 29 (East LaHave) to 816 (MPPP). Scheffé’s test following ANOVA showed the mean MPPP foraminiferal density to be significantly different from the other sites, which acted as a group. The most upstream assemblage was dominated by E. macrescens, the most downstream by M. fusca.There were no significant correlations between %C, %N and the mean foraminiferal densities of species. The mean population densities per 10 cm3 of E. macrescens differed between sites, (a) MPPP, (b) Dayspring and Upper LaHave, and (c) East LaHave forming non-overlapping subsets that will need to be monitored separately. Trochammina inflata mean population densities were distinct only at East LaHave. Miliammina fusca population densities presented a peculiar pattern, MPPP and East LaHave forming one group, and the intervening Dayspring and Upper LaHave sites forming another. The transformed mean proportions per site of E. macrescens and T. inflata were not significantly correlated with %C or %N, but those of M. fusca were positively correlated with both. It may be that high trace metal concentrations near Bridgewater are affecting foraminiferal distributions and abundances. This must be taken into account when using the benthic foraminiferal assemblage to assess the impact of the organic pollution remediation.

A Study of Co-occurrences of Foraminifera and Mussels in a Polluted Nova Scotian Wetland, Atlantic Canada

Abstract Studies of foraminiferal assemblages in intertidal marshes and subtidal creeks usually rely upon sediment samples collected along transects, such that associations with other organisms often go unnoticed. We show that ecologically useful data can be obtained by sampling that is stratified by substrate and microenvironment. The tidal wetland at Lower LaHave, Nova Scotia, Atlantic Canada (44º16′37.39″N, 64º19′46.45″W, area ∼1 km2) comprises mostly sandy sediment occupied largely by the low marsh grass Spartina alterniflora. The wetland is situated next to LaHave Estuary, which is polluted with domestic waste. Microenvironments within the marsh were sampled for total (living + dead) foraminiferal assemblages. The mass of dried sediment examined at each site was used to calculate the foraminiferal number (FN, number of foraminiferal tests per gram of sediment). Sediment samples from the intertidal grass beds reflect a typical low- to high-marsh zonal distribution of benthic foraminifera [FN = 24.7 ± 16.6 g−1 (mean ± standard deviation); n = 716 tests]. Samples from a tidal channel yielded few tests (FN = ∼0.3 ± 0.7 g−1; n = 22). Clutches of the mussel Mytilus edulis occurred in areas of strong current action within the channel and on lower energy slip-off slopes. Mussel clutches from the channel base yielded few tests (FN = ∼0.7 ± 0.7 g−1; n = 25), mostly Miliammina fusca. Clutches from slip-off slopes yielded a significantly richer assemblage (FN = 8.7 ± 4.6 g−1; n = 229) dominated by Elphidium umbilicatulum. We concluded that mussel clutches in low energy areas can be suitable habitat for E. umbilicatulum, either associated with structural complexity of the clutches or with waste products excreted by mussels that may stimulate growth of bacteria or microalgae upon which the foraminifera feed. The results from this study provide a baseline for examining the biotic impact of remediation of the LaHave River on the Lower LaHave wetland.

Foraminiferal assemblages along the intertidal zone of Itapanhaú River, Bertioga (Brazil)

Foraminifera found in intertidal zones have been successfully used in studies examining relative sea level monitoring around the world. For this purpose, it is necessary to establish the typical foraminiferal assemblages of different salinity regimes and sediment sub aerial exposition. In the present work we collected 27 sediment samples from 5 transversal transects in the mangroves of the Itapanhaú River (Bertioga, SP, Brazil). Transects were distributed along salinity and altitudinal gradients in order to study the community structure of recent foraminifera in terms of diversity and species composition. We identified 35 species and described 5 groups of species in different environmental settings, from downstream to upstream and from margin to landward in the mangrove forest, associated with salinity regime and sediment proportional exposure time. These variables seem to primarily control species distribution and community structure in the intertidal zone, although dissolution of calcareous taxa cannot be ruled out. The first group is dominated by Ammonia spp. and Elphidium spp., colonizes the mouth of the river on an unvegetated tidal flat in the lowest portion of the intertidal zone, under a polyhaline regime. This group exhibits the smallest sub aerial exposition (19,3%) as well as comparatively high species diversity. The second group is formed by a sample dominated by Trochammina inflata and Arenoparrella mexicana, obtained in a polyhaline area on the margin of the mangrove. The third group is dominated by Miliammina fusca and Ammotium spp., and colonizes mesohaline mangrove forests, with proportional exposure time of between 50 and 75%, and high species diversity. The fourth group comprises communities dominated by M. fusca and T. inflata, and colonizes the intermediate level in the interior of the mangrove forest, exhibiting high species diversity. The fifth group comprises communities broadly dominated by M. fusca, colonizing oligohaline margins and the highest level of polyhaline mangrove forests. This group exhibits the greatest sub aerial exposition and lowest species diversity of all five groups. Hence, these foraminifera groups may serve as a reference with which to interpret drilling core layers and reconstruct relative sea levels in other similar estuarine systems.

Foraminíferos e Tecamebas Bentônicos do Estuário do Rio Godineau, Golfo de Paria, Ilha de Trinidad

In the Godineau River Estuary, located in Trinidad Island (off the northeast coast of Venezuela), were found 114 taxa of foraminifera and 17 of thecamoebians in the dead fauna. Most of the identified foraminiferal species were rare because they were transported from the Gulf of Paria to this estuary. The autochthonous foraminiferal assemblage was represented by several tropical estuarine species such as Ammonia tepida, Ammotium salsum, Arenoparrella mexicana, Cribroelphidium excavatum, Ammonia parkinsoniana, Haplophragmoides wilberti, Miliammina fusca and Ammotium cassis. The thecamoebians assemblages, found in the inner part of this estuary, were dominated by Cyclopyxis spp., Centropyxis spp., Difflugia corona and Difflugia urceolata. The relative abundance of the main species of foraminifera and thecamoebians were analyzed through Q-mode and R-mode cluster analyses. Statistical results revealed the presence of three different environments in the Godineau River Estuary related to different hydrodynamic conditions and more or less oceanic or fluvial influence. The first sector represents the most confined region of the estuary and was mainly composed by agglutinated foraminifera together with thecamoebians. The second sector was located in the middle part of the estuary and was associated with the presence of brackish waters. The third sector denotes the outermost part of the estuary characterized by the greatest hydrodynamic activity and highest oceanic influence within the estuary. This sector was marked by the occurrence of a large number typical-marine foraminifera species.