Article

Foraminifera of Langebaan Lagoon salt marsh and their application to the interpretation of late Pleistocene depositional environments at Monwabisi, False Bay coast, South Africa

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Abstract

The relationship between marine benthic foraminifera assemblages and the environment has been examined from samples collected across the southern edge of Langebaan Lagoon. The assemblages show a vertical zonation that can be related primarily to altitude above mean sea level and secondarily to type and abundance of plant cover. The foraminiferal analysis distinguishes three zones: a high marsh zone dominated by a monospecific Trochammina inflata assemblage, a middle marsh zone consisting of variable abundances of T. inflata and Jadammina macrescens; and a low-marsh and tidal zone dominated by calcareous species such as Ammonia japonica, Ammonia parkinsoniana, Elphidium sp. A. Elphidium cf. articulatum and Quinqueloculina sp. The altitudinal range of these foraminiferal zones is used to reconstruct relative changes in late Pleistocene sea level from a succession exposed at Monwabisi on the False Bay coast.

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... Little has been published in South Africa regarding saltmarsh foraminiferal distribution in relation to tidal level. Franceschini et al. (2005) used salt-marsh foraminifera to investigate palaeoenvironments and palaeo-sea levels between the late Pleistocene and Holocene on the west coast of South Africa, although limited information was provided regarding the distribution of modern foraminifera. This highlights the importance of establishing a detailed modern analogue of foraminifera in a South African salt marsh, which can be used to quantify the relationship between microfauna and elevation in a local context. ...
... The results from Galpins salt marsh suggest that foraminiferal assemblages exhibit evidence of vertical zonation. The distribution of foraminiferal assemblages across the surface of the intertidal zone is, therefore, used as a proxy for elevation, though the duration and frequency of intertidal exposure must be considered as these factors also affect species distribution (Scott & Medioli, 1978;Jennings et al., 1995;Franceschini et al., 2005). ...
... Modern foraminiferal training sets are applied to downcore fossilised assemblages via a transfer function to reconstruct palaeomarsh surface elevations and, thereby, relative sea level (e.g., Barlow et al., 2013;Strachan et al., 2014). Franceschini et al. (2005) represent one of the few studies to successfully reconstruct relative sea level in South Africa using, in part, foraminifera. Our study encountered similar marsh species and successional patterns described for Langebaan Lagoon by Franceschini et al. (2005). ...
Article
Full-text available
Salt-marsh foraminifera are used as precise sea-level change indicators as surface assemblages vary in relation to their position in the tidal frame. Surface-sediment samples were collected across an elevation gradient at Galpins salt marsh, South Africa, to study the vertical distribution of foraminifera and their potential use for sea-level studies. The marsh is divided into three vertical zones (high marsh, middle marsh, and mud flats) represented by three assemblage groups, with agglutinated species restricted to the upper reaches of the marsh and calcareous species more dominant towards the intertidal channel. The high marsh area is dominated by Jadammina macrescens with a presence of Trochammina inflata. The middle marsh is characterised by both T. inflata and Miliammina fusca. Calcareous species found in the mud flats consist of Haynesina germanica, Ammonia batava, and Quinqueloculina sp. This paper describes how marsh foraminifera can be used to define small-scale vertical zones along modern marsh surfaces and how these zones correspond to floral zones. We demonstrate that marsh foraminifera have potential to be used as precise indicators for sea-level reconstructions in South Africa.
... Subsequent studies have provided additional knowledge and detailed descriptions regarding the vertical distribution of foraminifera, particularly along the Atlantic Ocean (Edwards and Horton, 2000;Gehrels, 1994;Gehrels and Newman, 2004;Patterson et al., 2004;Scott, Medioli, and Schafer, 2001) and the eastern Pacific coast (Patterson, Guilbault, and Clague, 1999;Williams, 1989). Studies conducted in Australia (Haslett, 2001;Horton and Edwards, 2003), New Zealand (Southall, Gehrels, and Hayward, 2006), and South Africa (Franceschini, McMillan, and Compton, 2005;Strachan et al., 2015) suggest that salt-marsh foraminiferal zones in the southern hemisphere mirror those of the northern hemisphere (Scott and Leckie, 1990). ...
... The aim of this study is to examine the distribution, abundance, and vertical zonation of dead and living foraminif-eral assemblages from two South African salt marshes. A comparison of foraminiferal zones from the two study sites and from two previous studies (Franceschini, McMillan, and Compton, 2005;Strachan et al., 2015) on salt-marsh foraminifera is undertaken to evaluate the applicability of regional training set in analysing sediment cores from South African salt marshes. ...
... The results from this study suggest that foraminiferal assemblages exhibit evidence of vertical zonation. Comparisons are made with the two existing South African studies (Franceschini, McMillan, and Compton, 2005;Strachan et al., 2015) and with other temperate salt marshes. Species tolerance ranges revealed broadly similar foraminiferal zonation between the Keiskamma and Knysna datasets. ...
Article
The global mean sea level is rising as a result of climate change and is likely to affect millions of people. It is essential to understand and quantify regional relative sea-level variability to be able to predict future changes. Proxy evidence is necessary for extending our understanding of past sea-level changes beyond the industrial era, and salt-marsh foraminifera have become an important tool for reconstructing late Holocene sea-level changes. In South Africa, little is known regarding the distribution of salt-marsh foraminifera and their use as sea-level indicators, thereby limiting their application in sea-level research. This study therefore describes the distribution of living and dead surface foraminifera from two study sites along the SE South African coastline. The full surface dataset has been compiled from 139 samples that are used to describe the contemporary distribution of salt-marsh foraminifera. Cluster analysis is used to define four biozones; high marsh, middle marsh, low marsh, and mudflats. In the high marsh, where environmental conditions reach the survival threshold, a greater abundance of agglutinated foraminifera occurs. In the low-marsh zone, where subaerial exposure is restricted and environmental conditions are usually stable, a greater diversity of calcareous species occurs. The tidal mudflats have the highest diversity of calcareous assemblages with some agglutinated taxa present. Distributions of living foraminiferal populations are similar to the population distributions of dead foraminifera at both sites in the low-marsh and mudflat zones. In the high-marsh zones, however, the living-to-dead ratio and distributions are different, which could be a result of different influences of environmental variables along with seasonal variations. This study provides insights into foraminiferal distributions along the SE coastline of South Africa, which will be useful for interpreting late Holocene sea-level changes.
... This work also included luminescence dating (Feathers, 2002) which produced ages (Middle to Late Pleistocene) generally younger than the chronology inferred from faunal and doubtful artifactual evidence. Hitherto the age(s) proposed for the False Bay and Duinefontyn dune systems have relied on low resolution, interpretative palaeontological and stratigraphic data, together with correlations of sedimentation increments with sea level cycles (Rogers, 1982(Rogers, , 1983; Barwis and Tankard, 1983;Butzer, 2004;Franceschini et al., 2005). The lack of an objective numerical dating framework on which to anchor and calibrate these approaches is reflected in the divergence of proposed chronologies. ...
... Lithostratigraphy of coastal Cenozoic sediments of the southern west coast (Roberts et al., 2007) Franceschini et al. (2005) proposed an entirely different chronology from the eastern sector of the False Bay sea cliff outcrops based on microfossils. They correlated a series of calcretised palaeosols and intervening sediment increments with glacial/interglacial marine isotope stages ranging back in time to MIS 11 at~400 ka. ...
... They correlated a series of calcretised palaeosols and intervening sediment increments with glacial/interglacial marine isotope stages ranging back in time to MIS 11 at~400 ka. Franceschini et al. (2005) conceded the tentative character of their chronology and suggested that it should be tested by luminescence dating. It is evident from the foregoing discussion that there is little consensus concerning the age range of the stratigraphic components of the False Bay dune plume, reflecting the dearth of objective dating criteria. ...
Article
This study examines two major late Quaternary coastal dune systems situated in the southwestern-most extremity of Africa. The False Bay and Duinefontyn dune plumes formed in close proximity, but under contrasting oceanographic regimes (warm Agulhas and cold Benguela oceanic current systems respectively). The False Bay and Duinefontyn dune plumes have hitherto lacked the objective, numerical chronology required to realize their full potential in unraveling the complex palaeo-oceanographic and palaeoclimatic history of the region. Here we present a dual amino acid racemizationn (AAR) and optically stimulated luminescence (OSL) chronological framework from the extensive three dimensional exposures in sea cliffs.At False Bay, three generations of dune deposition, corresponding with orbitally forced climatic/sea level cycles (MIS 7, MIS 5 and Holocene) were resolved, whereas the Duinefontyn Plume is dominated by MIS 5 and Holocene sedimentation. At False Bay and Duinefontyn, glacial periods are marked by the development of mature palaeosols, confirming the link between glacio-eustacy and dune deposition determined previously on the west and southern coasts of South Africa.Along the west coast dune plumes typify dunefield morphology, whereas shoreline-parallel dune cordons are commonly developed on the southern coast. These regional variations in dune system morphogenesis are largely controlled by contrasting wind and rainfall patterns. The attenuated dimensions of the MIS 5 plumes at False Bay and Duinefontyn may indicate a weakening of the South Atlantic Anticyclone during the Last Interglacial. At False Bay, stone artifacts illustrate a human presence in the region during MIS 7.
... However, in South Africa, there is limited baseline research into environmental controls on contemporary salt-marsh foraminifera (e.g. Franceschini et al., 2005;Strachan et al., 2015). Without such understanding, studies attempting to develop pre-industrial sea-level data, while useful for investigating regional patterns of sealevel rise, cannot be interpreted with confidence. ...
... In South Africa, two previous studies have documented the modern distribution of salt-marsh foraminiferal assemblages (Franceschini et al., 2005;Strachan et al., 2015). Research at Langebaan Lagoon assessed the relationship between marine benthic foraminiferal assemblages (living plus dead) and the environment, and determined that assemblages showed a vertical zonation related primarily to elevation and secondarily to type and abundance of vegetation (Franceschini et al., 2005). ...
... In South Africa, two previous studies have documented the modern distribution of salt-marsh foraminiferal assemblages (Franceschini et al., 2005;Strachan et al., 2015). Research at Langebaan Lagoon assessed the relationship between marine benthic foraminiferal assemblages (living plus dead) and the environment, and determined that assemblages showed a vertical zonation related primarily to elevation and secondarily to type and abundance of vegetation (Franceschini et al., 2005). A study at Kariega Estuary investigated the relationship between salt-marsh foraminifera (living versus dead) and vegetation zonation, but did not consider additional environmental variables beyond elevation (Strachan et al., 2015). ...
Article
Salt-marsh foraminifera are widely used as robust sea-level indicators. High-resolution Holocene sea-level reconstructions depend on the accurate characterization of modern foraminifera-environment relationships representative of a study site. We investigate the relationship between modern foraminiferal assemblage distribution and key environmental variables, viz. elevation above land levelling datum (LLD), sediment grain size, organic content, pH and salinity. We hypothesize that the distribution of modern salt-marsh foraminifera is primarily controlled by elevation above LLD.
... It classically dominates in the lower tidal marsh towards the tidal flat (Alve and Murray, 1999;Swallow, 2000), often related to muddy sediment (Lee et al., 1969;Müller-Navarra et al., 2016) (note that in most of the studies Quinqueloculina ssp. is indicated). However Franceschini (2005) reported the same unusual occurrence of Quinqueloculina ssp. in the higher part of the marsh area. Anomalously high abundances of the same species were as well observed at upper elevations in the Adriatic coast of Croatia (Shaw et al., 2016). ...
... Quinqueloculina seminula (Francescangeli et. sub.) (Shaw et al., 2016) (Franceschini et al., 2005) Trochammina inflata (elsewhere) ...
... Quinqueloculina seminula is widespread in marginal environments (Debenay and Guillou, 2002;Horton and Murray, 2007) and dominant in the lower tidal marsh/ tidal flat (Alve and Murray, 1999;Swallow, 2000). However as it has been discussed in Francescangeli et al. (submitted) Q. seminula could be able to move up along the tidal gradient venturing into the middle marsh (Franceschini et al., 2005;Horton and Murray, 2007;Shaw et al., 2016). ...
Thesis
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Extended abstract Foraminifera are one of the most abundant and diversified groups of unicellular organisms, ubiquitous in all marine habitats. In modern environments only a limited number of species are planktonic, the rest are benthic. Benthic foraminifera are able to organise in specific assemblages, in response to different environmental conditions. Due to their high sensitivity to environmental parameter changes, they have been increasingly used as bio-indicators of natural changes and anthropogenic alterations, at global and local scale. Furthermore their excellent preservation in fossil sediments enables them to be a suitable tool for palaeoecological and palaeoenvironmental reconstructions. The European Marine Strategic Framework Directive (MSFD, 2008/56/EC) requires the achievement of good ecological status for marine water bodies by 2020. Recently the consideration of benthic foraminifera for application under EU legislations has increased. The objective of the present PhD thesis is to study the response of benthic foraminifera to environmental changes in the Hauts-de-France region (Northern France). The coastal areas of the region extend about 240km along the southern part of the English Channel. The northern part of this area has experienced strong human modifications over the last 200 years, with the development of numerous anthropogenic activities. On the contrary the southwestern part includes mostly pristine areas. In this context the thesis project focuses on 3 main targets: i) describe the living foraminiferal communities in pristine and disturbed areas, ii) investigate the response of intertidal foraminifera to spatial and short-term environmental variations (seasons), iii) observe long term (hundred years) foraminiferal variations, across the intertidal areas of Hauts-de-France region. To achieve these objectives both living and fossil foraminiferal assemblages have been sampled in five sites along the intertidal areas of the region: from the most polluted Liane estuary with the harbour of Boulogne-sur-Mer, the Aa estuary, an embanked area of Grand-Fort-Philippe to the supposed less impacted one, the Bay of Somme passing by the Canche and Authie estuaries. A multiproxy approach based on foraminifera, environmental parameters and historical data, has been adopted to improve the interpretations. Here a synthesis of the main contents of the present PhD thesis: Chapter 1 introduces the study. It gives an overview on the world of foraminifers and places the thesis in its thematic and geographical context. In Chapter 2, the ecology of living benthic foraminifera is investigated in three annual surveys from the salt marsh area along the Canche estuary. Two distinctive foraminiferal zones are identified along the vertical tidal gradient, a middle-high salt marsh assemblage dominated by agglutinated taxa and a low salt marsh assemblage by calcareous specimens. Hyper tidal exposure drives the foraminiferal vertical zonation in accordance with the tidal frame. The article is currently under review in Estuarine, Coastal and Shelf Science. In Chapter 3, a seasonal survey is carried out from five intertidal areas. The objectives are to describe living benthic assemblages and to observe the influence of seasonality on driving foraminiferal distributions. The main outcome is that foraminiferal communities dominated by Haynesina germanica, vary consistently during the year. However they do not exhibit a clear and homogeneous trend across the 5 study sites. Benthic intertidal foraminifera show patchy distributions. In Chapter 4 long-term variations of foraminiferal benthic communities in a polluted area (Boulogne-sur-Mer harbour), and a pristine area (the Canche estuary), are investigated. The main objective is to monitor environmental changes over the last hundred years. In Boulogne-sur-Mer a pre-impacted period (reference conditions) is distinguished from an industrial period. The upper part of the core reflects better ecological conditions, indicating an environmental recovery. The article has been published in Marine Environmental Research. In the Canche estuary benthic foraminifera and historical aerial pictures, allow to reconstruct one hundred years of environmental transformations. A tidal flat has gradually replaced by a vegetated saltmarsh area. In the bottom part of the core, the sediment grain-size and the TOC are critical factors for the settlement and development of benthic foraminifera. Chapter 5 provides a synthesis and discussion of the main results. General conclusion and future perspectives are as well included. Résumé étendu Les foraminifères sont un des groupes les plus abondants et diversifiés d’organismes unicellulaires ubiquistes dans des habitats marins. Dans les environnements modernes, seul un petit nombre d’espèces est planctonique, le reste étant benthique. Les foraminifères benthiques sont capables de s’organiser en assemblages spécifiques en réponse aux différentes conditions environnementales. À cause de leur haute sensibilité aux changements des paramètres environnementaux, les foraminifères ont été de plus en plus utilisés comme bioindicateurs de changements naturels et d’altérations anthropiques, aux échelles locales et globales. De plus, leur excellente préservation dans les sédiments fossiles leur permet d’être un outil approprié pour des reconstructions paléoécologiques et paléoenvironnementales. La Directive-cadre Stratégie pour le milieu marin (DCSMM, 2008/56/CE) requiert que les masses d’eaux aient un bon statut écologique pour 2020. Récemment, l’utilisation des foraminifères benthiques pour l’application des lois européennes a augmenté. L’objectif de cette thèse de doctorat est d’étudier la réponse des foraminifères benthiques vivants aux changements environnementaux dans la région des Hauts-de-France. Les zones côtières des Hauts-de-France représentent environ 240 km le long de la rive Sud de la Manche. La partie nord de cette zone a subi de fortes modifications anthropiques durant les 200 dernières années, avec le développement des activités anthropiques. Au contraire, la partie sud-ouest inclut majoritairement des zones naturelles non contaminées. Dans ce contexte, le projet de thèse se focalise sur 3 objectifs principaux : i) décrire les communautés de foraminifères actuels vivants dans les zones naturelles contaminées et non contaminées, ii) décrypter la réponse des foraminifères intertidaux aux variations spatiales environnementales et à court-terme (à l’échelle des saisons), iii) observer les variations des foraminifères, sur le long-terme (centaines d’années), le long des environnements intertidaux des Hauts-de-France. Pour mener à bien ces objectifs, des assemblages de foraminifères fossiles et vivants ont été échantillonnés sur cinq sites le long des environnements intertidaux de la région : depuis l’estuaire de la Liane, le plus pollué, avec le port de Boulogne-sur-Mer, l’estuaire de l’Aa, à Grand-Fort-Philippe supposée être moins influencée par l’activité humaine, et la Baie de Somme en passant par les estuaires de la Canche et de l’Authie beaucoup plus « naturels ». Une approche alliant plusieurs outils basés sur les foraminifères, les paramètres environnementaux et les données historiques, a été utilisée pour développer les interprétations. Les principaux résultats de ce travail sont : Le chapitre 1 introduit l’étude. Il donne une vue d’ensemble sur le monde des foraminifères et place la thèse dans le thème et dans le contexte géographique. Dans le chapitre 2, l’écologie des foraminifères benthiques vivants est investiguée dans les marais salants de l’estuaire de la Canche à partir de 3 campagnes annuelles. Deux différentes zones de foraminifères sont identifiées le long du gradient tidal vertical. Un premier assemblage dominé par des taxons agglutinés se situe dans au milieu-haut du marais, alors que la partie basse est caractérisée par des spécimens carbonatés. L’exposition aux grandes marées engendre une zonation verticale des foraminifères, en fonction des amplitudes de marées. Ce chapitre soumis au journal Estuarine, Coastal and Shelf Science est actuellement en révision. Dans le chapitre 3, une étude saisonnière a été menée dans 5 zones intertidales. Les objectifs de cette étude sont de décrire les assemblages des foraminifères benthiques vivants et d’observer l’influence des saisons sur leur distribution. Le résultat majeur est que les communautés de foraminifères dominées par Haynesina germanica, varient considérablement pendant l’année. Cependant ces communautés ne montrent pas une tendance claire et homogène dans les 5 zones d’étude. Les foraminifères benthiques intertidaux montrent une distribution en tache. Le chapitre 4 présente l’étude des variations sur le long-terme des communautés de foraminifères benthiques dans des environnements pollués (port de Boulogne-sur-Mer) et non pollué (estuaire de la Canche). L’objectif principal est de mettre en évidence les changements environnementaux des cents dernières années. A Boulogne-sur-Mer, une période avant-pollution se distingue d’une période industrielle. La partie supérieure de la carotte reflète de meilleures conditions écologiques, indiquant un rétablissement de l’environnement après la période industrielle. Ces résultats sont publiés dans la revue Marine Environmental Research. Dans l’estuaire de la Canche, les foraminifères benthiques et des photographies aériennes historiques permettent de reconstruire cent ans de transformations environnementales. Une vasière a été graduellement remplacée par un marais végétalisé. Dans la partie basse de la carotte, la granulométrie et le Carbone Organique Total (TOC) sont des paramètres déterminants pour l’implantation et le développement des foraminifères benthiques. Enfin, le chapitre 5 présente une synthèse et discussion des résultats majeurs. Les conclusions générales et des perspectives futures sont incluses. Riassunto I foraminiferi sono un gruppo di organismi unicellulari tra i piu’ abbondanti e diversificati sulla biosfera terrestre. In prevalenza bentonici, sono diffusi in tutti gli ambienti marini odierni, dalle zone costiere ai remoti abissi. I foramniferi bentonici sono capaci di organizzarsi in specifiche associazioni, in relazione alle differenti sollecitazioni ambientali. Altamente sensibili alle variazione dei parametri ecologici, sono sempre più frequentemente utilizzati come bioindicatori allo stesso tempo di cambiamenti di origine naturale che antropogenica, a piccolo e lungo termine, sia su scala locale che globale. Inoltre la loro eccelente capacità di fossilizazzione li rende uno strumento ideale per condurre ricostruzioni paleoambientali e paleoecologiche. La direttiva europea “European Marine Framework Directive” (MSFD, 2008/56/EC) auspica il raggiungimento di un buon stato ecologico per tutti gli specchi d’acqua per l’inizio del 2020. Di recente è cresciuto l’interesse attorno all’applicazione dei foraminifera bentonici nel quadro delle suddette legislazione europee. In questo contesto il presente lavoro di tesi intente studiare la risposta dei foraminiferi bentonici moderni ai recenti cambiamenti ambientali nella regione Hauts-de-France (Francia Settentrionale). La line di costa del Hauts-de-France si estende per circa 240km bordando la parte meridionale del Canale della Manica. Le zone localizzate nella parte nord della regione sono state soggette a forte antropizzazione, che negli 200 anni ha profondamente modificato l’ecosistema costiero. Al contrario la parte più a sud include pricipalmente aree incontaminate. Il presente progetto di dottorato ruota attorno a tre principali obiettivi: i) descrivere le comunità intertidali dei foraminiferi bentonici viventi in zone incontaminate ed antropizzate, ii) investigare la risposta di foraminiferi intertidali a variazioni spaziali e temporali (stagionali), iii) osservare le variazioni temporali a lungo termine (centinaia di anni) che hanno caratterizzato le zone intertidali del Hauts-de-France. Per raggiungere i suddetti obiettivi le associazioni a foraminiferi, sia viventi che fossili, sono state campionate in cinque siti di studio attraverso le zone intertidali della regione: dal più inquinato estuario della Liane con il porto di Boulogne-sur-Mer , alla aree a flusso canalizzato di Grand-Fort-Philippe, alle sulla carte meno inquinati area estuarine del fiume Canche e Authie, per giungere alle zone incontaminate della Baia di Somme. Un approccio multidisciplinare basato su foraminiferi, parametri ambientali e dati storici, è stato utilizzato per migliorare le interpretationi. I principali contenuti del presente manoscritto di tesi vengono di seguito riassunti. Nel capito 1 viene introdotto lo studio, fornendo informazioni a carettere generale sul mondo dei foraminiferi, e le tematiche della tesi nel contesto geografico in esame. Nel Capitolo 2, l’ecologia dei foraminiferi bentonici viventi viene studiata, in tre anni successivi, lungo l’aree salmastre nell’estuario della Canche. Due distente associazioni sono identificate lungo il gradiente tidale verticale, un’associazione di medio-alta salt marsh (zona salstrastra vegetata) dominate da specie agglutinanti, ed un’associazione di bassa salt marsh, dominata da taxa calcarei. L’esposizione alla forte escurzione di marea determina la distribuzione verticale dei foraminifera in relazione al gradiente tidale. Il presente studio è attualmente in revisione nella rivista Estuarine Coastal and Shelf Science. Nel capitolo 3, un sondaggio stagionale è stato effettuato attraverso 5 siti di studio nella zone intertidali della regione. Gli obiettivi sono di descrivere le associazione a foraminiferi viventi e di osservare come la stagionalita’ influenza la distribuzione delle stesse. Il principale risultato è che le popolazioni a foraminiferi, dominate da Haynesina germanica, variano consistentemente durane l’anno di osservazione. Tuttavia nei cinque siti studiati non mostrano lo stesso andamento, in termini di diversità e abbondanza. Inoltre le comunità a foraminiferi bentonici presentano elevate variazioni su scala centrimentrica. Nel capitolo 4 le variazioni a lungo termine delle popolazioni bentoniche sono investigate nelle zone inquanate del porto di Boulogne-sur-Mer and nelle aree poco contaminite lungo l’estuario della Canche, tramite l’utilizzo di carote sedimentarie. Gli obbiettvi sono di monitore combiamenti ambientali avvenuti nei recenti secoli. Nel aree portuali di Boulogne-sur-Mer l’associazioni fossili distinguono chiaramente un periodo pre-industriale (definito come periodo di referenza per Boulogne-sur-Mer) da un periodo industriale. La parte alta della carota indica, nell’ultimo ventennio, un miglioramento delle condizioni ecologiche. Lo studio è stato pubblicato sulla rivista Marine Environmental research. Nell’estuario della Canche, foraminiferi bentonici e immagini storiche, hanno permesso la riscotruzione di cento anni di trasformazioni ambientali. I risultati evidenziano come un’iniziale piana tidale venga gradualmente rimpiazzata da un zona di saltmarsh. Nella parte bassa della carota, la granulometria e i contenuti in materia organica costituisco fattori critici per l’insediamento e sviluppo dei foraminiferi bentonici. Nel capitolo 5 i principali risultati vengono sintetizzati e discussi. Una conclusione generale e delle prospettive future vengono incluse nella stessa sezione.
... Species in bold have calcareous tests. et al., 1999; Wang and Chappell, 2001; Cann et al., 2002; Hippensteel et al., 2002; Horton et al., 2003; Edwards et al., 2004a; Franceschini et al., 2005; Horton et al., 2005; Woodroffe et al., 2005). Miliammina fusca appears at similar high elevations in tropical mangrove environments (Wang and Chappell, 2001; Horton et al., 2005; Woodroffe et al., 2005), but is more indicative of mid-intertidal, low marsh settings (i.e. between Mean Tide Level (MTL) and MHWST) in temperate regions (Patterson, 1990; Collins et al., 1995; Jennings et al., 1995; de Rijk and Troelstra, 1997; Ozarko et al., 1997; Alve and Murray, 1999; Horton, 1999; Hayward et al., 1999; Edwards et al., 2004a). ...
... Indeed, other studies have reported similar relationships between these environmental variables and elevation (de Rijk and Troelstra, 1997; Horton et al., 2003; Horton and Edwards, 2005; Franceschini et al., 2005). Consequently, the vast literature reporting foraminiferal surface assemblage zones which are vertically constrained according to the tidal frame suggests that foraminiferal species distributions in general are at least indirectly, but nevertheless significantly, related to elevation (Scott and Medioli, 1978, 1980a; Patterson, 1990; Jonasson and Patterson, 1992; Williams, 1994; Collins et al., 1995; Ozarko et al., 1997; Hayward et al., 1999; Horton, 1999; Horton et al., 1999; Patterson et al., 1999; Haslett, 2001; Wang and Chappell, 2001; Cann et al., 2002; Horton et al., 2003; Edwards et al., 2004a; Barbosa et al., 2005; Franceschini et al., 2005; Horton and Edwards, 2005; Woodroffe et al., 2005). ...
... Indeed, other studies have reported similar relationships between these environmental variables and elevation (de Rijk and Troelstra, 1997; Horton et al., 2003; Horton and Edwards, 2005; Franceschini et al., 2005). Consequently, the vast literature reporting foraminiferal surface assemblage zones which are vertically constrained according to the tidal frame suggests that foraminiferal species distributions in general are at least indirectly, but nevertheless significantly, related to elevation (Scott and Medioli, 1978, 1980a; Patterson, 1990; Jonasson and Patterson, 1992; Williams, 1994; Collins et al., 1995; Ozarko et al., 1997; Hayward et al., 1999; Horton, 1999; Horton et al., 1999; Patterson et al., 1999; Haslett, 2001; Wang and Chappell, 2001; Cann et al., 2002; Horton et al., 2003; Edwards et al., 2004a; Barbosa et al., 2005; Franceschini et al., 2005; Horton and Edwards, 2005; Woodroffe et al., 2005). Accordingly, where the crossshore gradient is minimal, a much greater uniformity of the fauna is apparent (Barbieri, 1996, 2001). ...
Article
Intertidal foraminifera from surface sediments are commonly used as a high-resolution indicator of sea-level change. The integrity of this approach is based upon the assumption that surface assemblages are similar in composition to their buried, fossil counterparts. This assumption may, in some cases, be inappropriate due to subsurface (or infaunal) production and taphonomic alteration. Here, we review the current understanding of foraminiferal production and taphonomic loss in intertidal environments, and examine the extent to which these processes can affect the development of foraminiferal assemblages in intertidal environments.
... After a lengthy pause, foram studies eventually recommenced from the early 1970s onward. Only 10 years ago Toefy (2010) remarked that foram research in South Africa has largely been conducted in geological contexts (Martin 1974(Martin , 1981McMillan 1974McMillan , 1987McMillan , 1993Cooper and McMillan 1987;Wright et al. 1990;Franceschini et al. 2005) and that with few exceptions (Toefy et al. 2003(Toefy et al. , 2005, studies on extant taxa were largely missing. This disparity has not changed very much since then, the few studies that were conducted mainly focussing on shallow water, salt marsh and mangrove environments (Schmidt-Sinns 2008; Strachan et al. 2015Strachan et al. , 2016Strachan et al. , 2017Fürstenberg et al. 2017). ...
... The comparison thus results in a surprisingly clear verdict, namely, that the foram communities of the two environments have very little in common. This also applies to the west coast, where the findings of Franceschini et al. (2005) in Langebaan Lagoon lead to the same conclusion. ...
Article
Full-text available
The study area is located on the inner Agulhas Bank around Plettenberg Bay, southern Cape Province, South Africa (Fig. 1). The Agulhas Bank is a transitional environment between the cold-temperate Benguela Current regime of the south-eastern South Atlantic and the warm-temperate Agulhas Current regime of the south-western Indian Ocean. Three distinct faunal assemblages (A, B and C) were identified in the study area. These are aligned in three consecutive, coast-parallel belts, assemblage A forming the inshore belt, assemblage C the offshore belt and assemblage B the in-between belt. Assemblage A is composed of Textularia -group individuals and Pararotalia sp., Cibicides lobatulus and Planorbulina mediterranensis . It occupies the nearshore belt up to 50 m water depth in sediments composed of very fine, fine and medium sands, with some coarse and very coarse sands. Assemblage B is composed of Bolivina cf. pseudopunctata , Cassidulina laevigata , Ammonia beccarii , Bolivina tortuosa and Bulimina elongata . It occupies water depths from 50–70 m, but may locally extend down to 90 m and, within the bay itself, upward to 20 m in fine and very fine sands containing some medium sand and mud. Assemblage C is dominated by Cassidulina laevigata , Bolivina cf. pseudopunctata , Bulimina elongata and Ammonia beccarii . In contrast to assemblage B which is dominated by B. cf. pseudopunctata , assemblage C is dominated by C. laevigata . Assemblage C is mainly confined to water depths of 70–100 m in sediments dominated by very fine sand (0.063–0.125 mm) containing some coarser sediment and mud. The distribution of the forams with respect to water depth, sediment composition and other environmental parameters suggests that it is mainly controlled by a combination of environmental parameters. No tangible relationship was found between the open shelf foraminifer communities and those of estuaries and lagoons along the South African coast.
... japonica and E. advenum) increased in abundance (Figure 17), which accounts for the observed infaunal-epifaunal ratios found in this study. These taxa indicate estuarine and littoral conditions as evidenced by previous work on foraminifera from the western shelf (McMillan, 1990b;Dale and McMillan, 1998;Dale and McMillan, 1999;Compton et al., 2002Franceschini and Compton, 2004;Franceschini et al., 2005;Franceschini and Compton, 2007;Herbert and Compton, 2007) and south coast sediments of South Africa (McMillan, 1990a). The increasing abundance of epifaunal foraminifera along the shelf of Namibia and western South Africa is indicative of environments where a more diverse range of microhabitats are available, e.g., hard and rocky substrates for these foraminifera to attach mixed with softer substrate to burrow into. ...
... A comparison between the onshore deposits (Dale and McMillan, 1999) and saltwater marsh foraminifera from southwestern South Africa (Franceschini and Compton, 2004;Franceschini et al., 2005;Franceschini and Compton, 2007) and the outer shelf foraminifera from western South Africa (Compton et al., 2002 indicate that taxa associated with littoral environments are preserved in onshore deposits and taxa associated with inner shelf environments are preserved in outer shelf sediments off western South Africa. This is consistent with data from this study in which inner shelf species are preserved in outer shelf sediments of Namibia. ...
... Over the past decades the distribution and ecology of salt marsh foraminifera have been largely investigated (among these Murray, 1971;Scott and Medioli, 1978;Hayward and Hollis, 1994;Alve and Murray, 1999;Franceschini et al., 2005;Fatela et al., 2009;Camacho et al., 2015;Müller-Navarra et al., 2016). These studies point out that, although biogeography and local phenomena distributions might strongly influence the vertical zonation of marsh foraminifera, high-marsh and low-marsh fauna are marked by the same or similar groups of species in discontinuous geographic locations (Sen Gupta, 1999). ...
... It classically dominates in the lower tidal marsh towards the tidal flat (Alve and Murray, 1999;Swallow, 2000), often related to muddy sediment (Lee et al., 1969; Müller-Navarra et al., 2016) (note that in most of the studies Quinqueloculina ssp. is indicated). However Franceschini et al. (2005) reported the same unusual occurrence of Quinqueloculina ssp. in the higher part of the marsh area. Anomalously high abundances of the same species were as well observed at upper elevations at the Adriatic coast of Croatia (Shaw et al., 2016). ...
Article
In the present study we investigate the ecology and distribution of living benthic foraminifera to test the effect of hyper tidal exposure and their suitability as sea level indicators. Within a salt marsh area along the Canche Estuary (northern France), four transects were sampled to see the effects of maximal tidal constraints (shore transects) and minimal tidal constraints (alongshore transects). Multivariate analyses have been performed to determine the correlations between biotic (foraminiferal absolute abundances) and abiotic factors (elevation, grain-size, TOC and total sulphur). For each of the principal benthic foraminiferal species the tolerance to subaerial exposure have been estimated as well. Two distinctive foraminiferal zones have been identified along the vertical tidal gradient: a zone I in the higher part of the salt marsh dominated by agglutinated and porcelaneous taxa, and a zone II in the lower one dominated by hyaline specimens. Hyper tidal exposure constraints the foraminiferal vertical zonation in accordance with the tidal frame. However it does not constitute a threshold parameter able by itself to explain all the faunal variations in the Canche Estuary. For sea level indicators, foraminifera should be considered relative to tidal subaerial exposure rather than to absolute altitude.
... Where linear species-environment responses are demonstrated, Partial Least Squares (PLS) is the most widely used technique (e.g., Stone and Brooks, 1990;Rossi et al., 2011). These methods are reviewed in detail by Birks (1995Birks ( , 2003Birks ( , 2010, Barlow et al. (2013) and Kemp and Telford (2015), and have been applied to reconstruct past sea-level changes in a wide range of geographical areas, including the Atlantic coast of the USA (e.g., Gehrels, 2000;Edwards et al., 2004aEdwards et al., , 2004bGehrels et al., 2002Gehrels et al., , 2004Gehrels et al., , 2005Kemp et al., 2009aKemp et al., , 2009bKemp et al., , 2011Kemp et al., , 2013Wright et al., 2011), the Atlantic coast of Europe (e.g., Gehrels et al., 2001;Edwards, 2005, 2006;Leorri et al., 2010;Long et al., 2014;Barlow et al., 2014;Barnett et al., 2015), eastern Canada (e.g., Patterson et al., 2004;Gehrels et al., 2005;Barnett et al., 2016), west coast of Canada (Guilbault et al., 1996), South Africa (Franceschini et al., 2005;Strachan et al., 2014), Iceland Saher et al., 2015), Australia (Woodroffe, 2009;Gehrels et al., 2012), New Zealand (Gehrels et al., 2008;Grenfell et al., 2012) and Malaysia (Culver et al., 2015). Despite this vast literature, few studies have been conducted along the Pacific coast of the USA. ...
... Trochammina inflata and more prominently J. macrescens are also dominating higher elevations of the high marshes at both sites where they are accompanied by T. irregularis and M. petila. Jadammina macrescens and T. inflata have frequently been reported from middle marsh (Guilbault et al., 1996;Jennings and Nelson, 1992;Nelson et al., 2008;Hawkes et al., 2010;Engelhart et al., 2013, Milker et al., 2015a and the highest marsh environments (e.g., Patterson, 1990;de Rijk and Troelstra, 1997;Horton et al., 1999a;Wang and Chappell, 2001;Hippensteel et al., 2002;Edwards et al., 2004a;Franceschini et al., 2005;Woodroffe and Horton, 2005). Trochamminita irregularis (often grouped with T. salsa) has commonly been detected as a dominant species in the high and highest marsh in North American Pacific marshes (Hawkes et al., 2010;Engelhart et al., 2013;Milker et al., 2015aMilker et al., , 2015b and in New Zealand (e.g., Hayward et al., 2004;Southall et al., 2006) and Tasmania (Callard et al., 2011). ...
Article
Salt-marsh foraminifera are frequently used around the world as proxies in paleoenvironmental studies of sea-level change. Quantitative reconstructions of sea-level change use transfer functions which are based on the vertical zonation of salt-marsh foraminifera with respect to the tidal frame. This paper explores for the first time the environmental factors that control the foraminiferal assemblages in Southern California marshes using modern surface samples (1 cm thick) from two marshes Seal Beach and Tijuana Estuary. The dead foraminiferal assemblages demonstrate distinct zonation across the salt-marsh surfaces which is primarily related to elevation. Other variables less important than elevation such as O2, temperature, salinity and pH additionally control the distribution pattern of these assemblages.
... In contrast to tropical environment relative sea-level reconstructions, reconstructions from temperate areas have been dominated by microfossil based reconstruction techniques (e.g. Scott and Medioli, 1978, 1980; Horton et al., 1999; Gehrels, 2000; Shennan et al., 2000; Campeau et al., 2000; van de Plassche, 2000; Horton et al., 2003; Horton and Edwards, 2005; Franceschini et al., 2005; Ruiz et al., 2005). Early sea-level research relied heavily on the use of pollen assemblages as a proxy for sea level with the first sea-level curve being produced by Godwin (1940) in the English Fenland. ...
Article
We investigated the mangroves of Southeast Sulawesi, Indonesia, to assess their potential as proxies for reconstructing sea level during the Holocene. Initial investigations confirmed that the mangrove species demonstrate zonations parallel to the shoreline and are dominated by the family Rhizophoraceae with Avicennia, Heritiera and Sonneratia also important constituents of the mangroves.We investigated the vertical distributions of pollen assemblages at three sites. Partial CCA analysis demonstrated that at all three sites, elevation was a significant control on the distribution of pollen assemblages in surface samples. We combined the three contemporary transects to develop a regional transfer function to explain the relationship between the surface assemblages and elevations using the Maximum Likelihood (ML) method. The developed transfer function indicated mangrove pollen can be used as a precise indicator of past sea levels with an error of ± 0.22 m. The transfer function was applied to two fossil cores from the Wakatobi Marine National Park and evaluated using the Modern Analogue Technique. Both cores showed similar patterns in changes of palaeo mangrove elevation and had modern analogues in the contemporary training set. We conclude that mangrove pollen is a suitable proxy for reconstructing sea level in tropical environments.
... The use of salt-marsh foraminifera to reconstruct relative sea-level change has been limited to a single published study at Langebaan. 33 Here we introduce an established sea-level proxy to determine proof of concept for South African sea-level research. This technique has the potential to contribute to our incomplete understanding of past sea-level change along the southern African coastline. ...
Article
Full-text available
A late Holocene sea-level curve for the east coast of South Africa South Africa's extensive and topographically diverse coastline lends itself to interpreting and understanding sea-level fluctuations through a range of geomorphological and biological proxies. In this paper, we present a high-resolution record of sea-level change for the past ~1200 years derived from foraminiferal analysis of a salt-marsh peat sequence at Kariega Estuary, South Africa. A 0.94-m salt-marsh peat core was extracted using a gouge auger, and chronologically constrained using five radiocarbon age determinations by accelerator mass spectrometry, which places the record within the late Holocene period. Fossil foraminifera were analysed at a high downcore resolution, and a transfer function was applied to produce a relative sea-level reconstruction. The reconstructed sea-level curve depicts a transgression prior to 1100 cal years BP which correlates with existing palaeoenvironmental literature from southern Africa. From ~1100 to ~300 cal years BP, sea levels oscillated (~0.5-m amplitudes) but remained consistently lower than present-day mean sea level. The lowest recorded sea level of −1±0.2 m was reached between 800 and 600 cal years BP. After 300 cal years BP, relative sea level has remained relatively stable. Based on the outcomes of this research, we suggest that intertidal salt-marsh foraminifera demonstrate potential for the high-resolution reconstruction of relative sea-level change along the southern African coastline.
... In addition, micro-and macrofossils may contribute to reconstruct relative sea-level histories at high precision (e.g. Franceschini et al. 2005;Woodroffe and Long 2009). Intertidal and supratidal estuarine sedimentary successions are particularly useful in this context because they record both sea-level fluctuations and changes which may have occurred in upstream terrestrial drainage basins (e.g. ...
Article
Full-text available
A new tool and method for collecting undisturbed subsurface samples in estuarine environments by means of trenching, timbering and sectioning is presented. Smoothing of sidewalls is achieved by a so-called cutting sediment profiler (CutSprof), while water draining into the trench is cleared by pumping. From smoothed sidewall sections, undisturbed thin sediment slices can then be collected for micromorphological and microfacies analyses. Results demonstrating the successful application of this procedure are presented for salt marshes of the Bensafrim River estuary (Lagos, Algarve, Portugal). In addition to palaeo-reconstructions in salt marsh settings, the CutSprof would be highly suitable in various other research domains as well as for environmental management purposes, particularly where sampling below the groundwater table is desirable to explore, for example, animal–sediment relationships in tidal-flat and mangrove ecosystems as well as the dynamics of coastal wetlands today threatened by ever-increasing anthropogenic influence.
... The use of salt-marsh foraminifera to reconstruct relative sea-level change has been limited to a single published study at Langebaan. 33 Here we introduce an established sea-level proxy to determine proof of concept for South African sea-level research. This technique has the potential to contribute to our incomplete understanding of past sea-level change along the southern African coastline. ...
Article
South Africa's extensive and topographically diverse coastline lends itself to interpreting and understanding sea-level fluctuations through a range of geomorphological and biological proxies. In this paper, we present a high-resolution record of sea-level change for the past ∼1200 years derived from foraminiferal analysis of a salt-marsh peat sequence at Kariega Estuary, South Africa. A 0.94-m salt-marsh peat core was extracted using a gouge auger, and chronologically constrained using five radiocarbon age determinations by accelerator mass spectrometry, which places the record within the late Holocene period. Fossil foraminifera were analysed at a high downcore resolution, and a transfer function was applied to produce a relative sea-level reconstruction. The reconstructed sea-level curve depicts a transgression prior to 1100 cal years BP which correlates with existing palaeoenvironmental literature from southern Africa. From ∼1100 to ∼300 cal years B P, sea levels oscillated (∼0.5-m amplitudes) but remained consistently lower than present-day mean sea level. The lowest recorded sea level of -1±0.2 m was reached between 800 and 600 cal years B P. After 300 cal years B P, relative sea level has remained relatively stable. Based on the outcomes of this research, we suggest that intertidal salt-marsh foraminifera demonstrate potential for the high-resolution reconstruction of relative sea-level change along the southern African coastline.
... The abundant presence of the high salinity-tolerant gastropod Tomichia ventricosa, as well as gastropods less tolerant to salinity, indicate seasonal rainfall patterns similar to present. Near Swartklip, the Monwabisi palaeo-lagoon preserves similar raised palaeoestuarine and lagoonal sediments (Franceschini et al., 2005 ). Based on foraminifera assemblages, the depositional environments of the area include an intertidal flat from the penultimate interglacial (MIS 7–8), establishing a raised estuarine shoreline at that time. ...
Chapter
Full-text available
The South African coast contains abundant estuaries and lagoons, most of which originated as drowned river valleys incised during Quaternary sea-level fall and subsequently drowned and/or infilled during rising interglacial sea-levels. This chapter discusses these changes and highlights the geomorphological and sedimentological evolution of several southern African estuaries during the Pleistocene to present. The development, infilling and positioning of incised valley systems is mainly controlled by sea-level variation as well as fluvial and marine sediment supply. Most contemporary estuaries in southern Africa show dramatic responses to shorter term sea-level fluctuations and sediment supply during the Holocene. Barring anthropogenic interference, the dynamic nature of estuaries, dictated by their transient position and geomorphic character within an incised valley, is considered to fluctuate on centennial to millennial timescales.
... These genera were regarded as synonyms of the genus Jadammina by Loeblich & Tappan (1987). The majority of the foraminiferal workers currently use the name Jadammina (or Trochammina) macrescens to describe specimens from saline lakes and salt marshes around the world (e.g., Warren, 1957;Phleger, 1965;Boltovskoy & Lena, 1966;Tufescu, 1969;Jakovskaja & Mikhalevich, 1972;Saffert & Thomas, 1998;Gehrels & van de Plassche, 1999;Debenay et al, 2001;Javaux & Scott, 2003;Gehrels & Newman, 2004;Barbosa et al., 2005;Franceschini et al., 2005;Frenzel et al., 2005;Langer & Lipps, 2006;Pascual & Rodriguez-Lazaro, 2006;Vasquez Ribeiros et al., 2007;Wilson et al., 2008). However, in our opinion the relationship of Bartenstein's Jadammina to Von Daday's Entzia has never been fully resolved owing to the lack of type specimens. ...
... Quinqueloculina seminulum is widespread in marginal environments (Debenay and Guillou, 2002;Horton and Murray, 2007) and dominant in the lower tidal marsh/ tidal flat (Alve and Murray, 1999;Swallow, 2000). However, this taxon could be able to move up along the tidal gradient into the middle marsh (Franceschini et al., 2005;Horton and Murray, 2007;Shaw et al., 2016). Therefore the upper interval of the core shows how initial patchy vegetation developed rapidly, covering the whole tidal area and leading to the present landscape configuration. ...
Article
A multiproxy approach based on benthic foraminifera, sediment grain-size, total organic carbon content, major and trace element concentrations, and radionuclide activities was used to investigate the recent landscape evolution of the Canche Estuary (eastern English Channel, France). In the present study the radiometric dating based on 210Pb and 137Cs activities could only establish that the sediments were deposited recently. As an alternative method, aerial historical pictures were used for the first time to date core sediments as well as to enhance the palaeoenvironmental interpretations. In approximately one hundred years, an initial naked tidal flat has been gradually replaced by a vegetated salt marsh. In the bottom part of the core, foraminiferal assemblages are dominated by Cribroelphium excavatum and Elphidium margaritaceum. Haynesina germanica is the most abundant taxon in the middle part of the core while Entzia macrescens is dominant in the upper part. The sediment core represents a typical fining-upward succession in a low-impacted tide-dominated estuary filled by progradation. Our outcomes highlight how a multidisciplinary approach based on abiotic and biotic parameters is essential for understanding complex transitional areas like estuaries. When dating is not provided by classic radiometric methods, historical pictures (<100 years) may constitute a valuable alternative method to reconstruct recent environments.
... The earliest foraminifera date back to the Cambrian, but they have been morphologically consistent since the Permian (Murray, 2006). In southern Africa, foraminifera provide evidence for sea-level change and changes in sedimentary conditions (McMillan, 2003;Franceschini et al., 2005;Strachan et al., 2014Strachan et al., , 2015, upwelling processes (Giraudeau, 1993;Little et al., 1997), and for temperature fluctuations and changes associated with El Niño and the Little Ice Age (Herbert, 1987). There has also been considerable research into the contemporary ecologies of living foraminifera in the Benguela Upwelling Zone, the Mozambique Channel and the Agulhas Bank (Schmiedl et al., 1997;Licari and Mackensen, 2005;Leiter and Altenback, 2010). ...
Chapter
Minerogenic microfossils are abundantly preserved in sedimentary sequences from a wide range of aquatic environments, including shallow and deep ocean basins, lakes, wetlands and estuaries, and in environments with a range of pH, temperature, salinity and nutrient loads. In southern Africa, pollen is used more commonly as a palaeoenvironmental proxy than are minerogenic microfossils, despite the wider range of environmental variables to which minerogenic micro-organisms respond. Palaeoenvironmental reconstructions in southern Africa that have utilised some of these microfossils demonstrate their value, particularly in multiproxy analyses, when comparing microfossil community changes with those represented by pollen, charcoal and stable isotopes. This chapter outlines the minerogenic microfossils that are most commonly examined globally, and discusses some specific case studies from southern Africa that demonstrate the utility of microfossils in reconstructing Quaternary palaeoenvironments. We argue that efforts should be made to expand the use of minerogenic microfossils in southern African palaeoenvironmental studies, given the valuable information they provide, both as proxies and through facilitating isotope analysis and dating.
... In contrast to tropical environment relative sea-level reconstructions, reconstructions from temperate areas have been dominated by microfossil based reconstruction techniques (e.g. Medioli, 1978, 1980;Horton et al., 1999;Gehrels, 2000;Shennan et al., 2000;Campeau et al., 2000;van de Plassche, 2000;Horton et al., 2003;Horton and Edwards, 2005;Franceschini et al., 2005;Ruiz et al., 2005). Early sea-level research relied heavily on the use of pollen assemblages as a proxy for sea level with the first sea-level curve being produced by Godwin (1940) in the English Fenland. ...
Preprint
We investigated the mangroves of Southeast Sulawesi, Indonesia, to assess their potential as proxies for reconstructing sea level during the Holocene. Initial investigations confirmed that the mangrove species demonstrate zonations parallel to the shoreline and are dominated by the family Rhizophoraceae with Avicennia, Heritiera and Sonneratia also important constituents of the mangroves.We investigated the vertical distributions of pollen assemblages at three sites. Partial CCA analysis demonstrated that at all three sites, elevation was a significant control on the distribution of pollen assemblages in surface samples. We combined the three contemporary transects to develop a regional transfer function to explain the relationship between the surface assemblages and elevations using the Maximum Likelihood (ML) method. The developed transfer function indicated mangrove pollen can be used as a precise indicator of past sea levels with an error of ±0.22 m. The transfer function was applied to two fossil cores from the Wakatobi Marine National Park and evaluated using the Modern Analogue Technique. Both cores showed similar patterns in changes of palaeo mangrove elevation and had modern analogues in the contemporary training set. We conclude that mangrove pollen is a suitable proxy for reconstructing sea level in tropical environments.
... Sea-level investigations in salt marshes using foraminiferal transfer functions, that have been used to good effect elsewhere (e.g. Gehrels, 2000), are still being developed in South Africa ( Franceschini et al., 2005;Strachan et al., 2014Strachan et al., , 2015 and only the results of a pilot study span- ning less than 2000 years ( Strachan et al., 2014) have yet been reported. ...
Article
Sea-level change around southern Africa (southern Namibia, South Africa, southern Mozambique) since Termination I has been quantified using a variety of indicators. Existing and new data are reviewed to provide a baseline for future studies and identify key research needs and opportunities in the region. While the southern African records broadly agree with other far-field records, detailed Holocene records present as-yet unresolved discrepancies with glacial isostatic adjustment (GIA) model predictions. Two domains, the west coast and east coast are considered. Radiocarbon dated saltmarsh facies and marine shells in life position provide the basis for the west coast sea-level curve back to 9 ka BP. Given the age and elevation uncertainties, a Mid-Holocene highstand of +2 to +4 m is suggested between 7.3 and 6 ka BP, as are several Late Holocene oscillations of <1 m amplitude. On the east coast, fewer data are available for the Mid to Late Holocene (post 7 ka BP) compared to the west, but many submerged indicators are available back to 13 ka BP. Reappraisal of existing data suggests a sea-level curve similar to that of the west coast. In both instances, the resolution of existing sea-level index points is neither sufficient to accurately constrain the magnitude and timing of the peak highstand nor the existence of minor inferred subsequent oscillations. Between 13 and 7 cal ka BP chronological and geomorphological evidence (submerged shoreline complexes) suggest several alternating periods of slow and rapid sea-level change. Despite abundant data, the indicator resolution to quantify these changes remains elusive.
... The vertical distribution of thecamoebians (from~MHHW to supratidal environments) observed in our low-salinity study sites is consistent with that observed elsewhere in the North Atlantic (Barnett et al., 2017a). Moreover, J. macrescens is often observed at the upper intertidal boundary in tropical and temperate environments (e.g., Patterson, 1990;Franceschini et al., 2005;Horton and Edwards, 2006;Vance et al., 2006;Wright et al., 2011). ...
Article
Full-text available
We assessed the use of δ¹³C, TOC and C/N values of bulk sedimentary organic matter (OM) to reconstruct paleoenvironmental and relative sea-level change from mangrove environments in Puerto Rico. The modern distribution of δ¹³C, TOC and C/N values was described from 63 vegetation and 59 surface sediment samples collected from three sites containing basin and riverine mangrove stands, and was compared to microfossil (foraminiferal and thecamoebian) assemblages. Four vertically-zoned environments were identified: tidal flat (δ¹³C: −18.6 ± 2.8‰; TOC: 10.2 ± 5.7%; C/N: 12.7 ± 3.1), mangrove (δ¹³C: −26.4 ± 1.0‰; TOC: 33.9 ± 13.4%; C/N: 24.3 ± 6.2), brackish transition (δ¹³C: −28.8 ± 0.7‰; TOC: 40.8 ± 11.7%; C/N: 21.7 ± 3.7), and freshwater swamp (δ¹³C: −28.4 ± 0.4‰; TOC: 42.8 ± 4.8%; C/N: 17.0 ± 1.1). These environments had distinct δ¹³C, TOC and C/N values, with the exception of the brackish transition and freshwater swamp zones that were difficult to distinguish on a geochemical basis alone. The foraminiferal assemblages were complicated by a group that did not show a relationship to elevation due to the presence of calcareous foraminifera occurring above mean higher high water (MHHW), likely resulting from washover or transport by storms. However, the ratio of foraminifera to thecamoebians (F/T) along with δ¹³C, TOC and C/N values refines the distinction between brackish and freshwater environments. Using linear discriminant analysis, we applied the δ¹³C, TOC, C/N and F/T distributions to a 1.7 m core containing a continuous sequence of Rhizophora mangle peat, which began accumulating at ~1650–1930 CE. Together, microfossils, δ¹³C, TOC, and C/N values, and the core chronology from ¹³⁷Cs and radiocarbon dating revealed that sediments in the core likely accumulated in response to anthropogenic sediment delivery, making it unsuitable for relative sea-level reconstruction. We caution that in the absence of detailed litho-, bio-, chemo-, or chrono-stratigraphic analyses as presented here, care should be taken in interpreting sea-level histories derived from single dates on mangrove peats.
... North Atlantic Ocean -Portugal, Aveiro (Martins et al., 2019); France, Bay of Biscay (Rouvillois, 1974;Schweizer et al., 2011); Ireland west coast (Jones, 1994); Irish Sea, Shanganagh (Haynes et al., 1995); Scotland, Hebridean Shelf (Murray, 2003), Loch Sunart (Cage & Austin, 2008), Dunstaffnage (Bird et al., 2019). South Atlantic Ocean -Senegal (Debenay & Redois, 1997); Mauritania, (Hesemann, 2017); South Africa, Monwabisi (Franceschini et al., 2005), Soldanh Harbour, 10 m (sample 4740, M. Langer, ...
Article
A quest to collect live specimens of the well-known foraminifer Ammonia beccarii for sequencing has led to the recognition of five molecular species in Europe all related to it, but no live beccarii itself. The five molecular species all clump together in one clade (T3 clade) of the Ammonia phylogenetic tree. All are characterised by large size, ornament on the umbilical side and a deep spiral, sutural fissure on the spiral side (beccarii morphogroup). All five molecular species can be discriminated based on distinct morphological differences as Ammonia batava (North Sea, northeast Atlantic, west Mediterranean Sea), A. corallinarum (northeast Atlantic, west Mediterranean Sea), A. pawlowskii n.sp. (Mediterranean Sea, west Indian Ocean), A. falsobeccarii (North Sea, east Atlantic seaboard, Mediterranean Sea, Persian Gulf), and A. neobeccarii (Mediterranean and Black seas). Using morphological characters a further four species are recognized in the beccarii morphogroup for which presently no sequences are available: A. beccarii (Mediterranean Sea, northeast Atlantic), A. batava compacta (west Atlantic seaboard), A. debenayi n.sp. (west Indian Ocean), A. venecpeyreae n.sp. (west Mediterranean Sea, Gulf of Aden). One species, A. japonica (China, Japan, South Korea), for which sequences have been obtained, is included in the beccarii morphogroup based on morphological characteristics but differs genetically from the beccarii group. .A further species, similar to A. falsobeccarii with secondary sutural openings on the spiral side but probably not part of the beccarii morphogroup because it lacks the spiral sutural canal typical of the group, is described as new – A. langeri (Indian Ocean, East Indies, south Australia). A growth series of A. beccarii topotypes from Rimini, north Adriatic Sea, is illustrated to aid in its recognition and a neotype designated and illustrated. Extinct fossil members of the beccarii morphogroup include A. ikebei, A. inflata, A. italica, A. nakazatoensis, A. punctastogranosa, A. reyi, A. togopiliensis, A. viennensis and A. voorthuyseni.
... These genera were regarded as synonyms of the genus Jadammina by Loeblich & Tappan (1987). The majority of the foraminiferal workers currently use the name Jadammina (or Trochammina) macrescens to describe specimens from saline lakes and salt marshes around the world (e.g., Warren, 1957; Phleger, 1965; Boltovskoy & Lena, 1966; Tufescu, 1969; Jakovskaja & Mikhalevich, 1972; Saffert & Thomas, 1998; Gehrels & van de Plassche, 1999; Debenay et al, 2001; Javaux & Scott, 2003; Gehrels & Newman, 2004; Barbosa et al., 2005; Franceschini et al., 2005; Frenzel et al., 2005; Langer & Lipps, 2006; Pascual & Rodriguez-Lazaro, 2006; Vasquez Ribeiros et al., 2007; Wilson et al., 2008). However, in our opinion the relationship of Bartenstein's Jadammina to Von Daday's Entzia has never been fully resolved owing to the lack of type specimens. ...
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Contemporary and relict (subsurface) intertidal foraminiferal dead assemblages were collected from a site near to Cocoa Creek, north Queensland, Australia, and analysed for the purpose of understanding fossil assemblage development and preservation. A marked dichotomy was identified between dead foraminiferal assemblages within mangrove sediments and those within adjacent mudflat sediments. Mangrove assemblages were almost exclusively represented by agglutinated species (mainly Arenoparrella mexicana, Haplophragmoides wilberti, Milliammina fusca, M. obliqua, Trochammina inflata) while calcareous species dominated the mudflat (mainly Ammonia aoteana, Pararotalia venusta, Parrellina hispidula). Surface and subsurface test abundances were also an order of magnitude greater within mudflat sediments (1000–3000 tests per cm3) than in the sediments beneath the mangroves (100–300 tests per cm3). Statistically significant differences in the abundance of calcareous and agglutinated tests between wet and dry seasons within the mangrove suggest that tests are systematically lost from this part of the system on an annual basis. A model of assemblage formation under shoreface progradation is presented which makes a direct link between surface assemblages, post-depositional processes and the composition and environmental resolution of the fossil assemblages entering the stratigraphic record. Assemblages within the mangrove undergo rapid taphonomic loss and are then overprinted during burial by the deep infaunal communities associated with the prograding higher-elevation environments. As such, much of the eventual mangrove sequence is represented entirely by assemblages produced relatively recently within an upper mangrove environment, and therefore cannot be differentiated according to elevation at the time of deposition. In addition, organic enrichment of upper mudflat deposits by mangrove roots, which occurs during progradation, results in the dissolution of calcareous tests from an ~ 40 cm thick stratigraphic interval. It is argued that in order to reliably recognise the changes to foraminiferal assemblages which occur during burial, assemblages must be compared with respect to stratigraphy, rather than reflexively downcore.
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Globally, one of the two most common shallow-marine and estuarine foraminiferal genera is Ammonia. Over the past 50 years, the majority of workers have identified specimens in this genus as belonging to just 1-3 cosmopolitan species - A. beccarii, A. tepida and A. parkinsoniana. This has been partly because of the problems of discriminating the Ammonia species based entirely on shell morphology and partly because of a 1974 laboratory study that claimed to have shown that all morphologies were merely ecophenotypic variants of one species - a conclusion that molecular studies have proven to be unequivocally wrong. In this study we recognize, describe and figure sixty-seven living species and infraspecies of Recent Ammonia and two closely-related genera (Acarotrochus, Pseudoeponides) from around the world and summarize their ecological and biogeographic distribution. Twenty-six species and two subspecies are recognized by DNA sequencing and shown to be morphologically distinguishable. A further 39 morphospecies and one subspecies, that have not yet been sequenced, have sufficiently distinct morphology to be recognized. Canonical variates analysis using 42 measured or assessed morphological characters shows that the majority of these species can be readily discriminated by their test morphologies, although a few of the less-ornamented molecular species are verging on being pseudocryptic. Molecular sequencing of the type species of Challengerella (C. bradyi) and Helenina (H. anderseni) places them within our Ammonia clade. Here we continue to recognize the morphologically highly distinct genera Pseudoeponides (subjective senior synonym of Helenina) and allied Acarotrochus. Twenty new species or subspecies are described (molecular T types in brackets): Ammonia abramovichae (T8), A. akitaae, A. aoteana australiensis (T5A), A. arabica (T26), A. ariakensis quiltyi, A. buzasi (T11), A. fajemilai, A. goldsteinae, A. goodayi, A. haigi (T25), A. hattai, A. jorisseni (T23), A. justinparkeri, A. kitazatoi (T10), A. morleyae (T12), A. shchedrinae, A. turgida almogilabinae (T22M), Acarotrochus lippsi, Pseudoeponides hottingeri and P. dubuissoni. Aneotype is designated for A. veneta (Schultze 1854) (T1). We recognize 67 Ammonia and related taxa in this study but speculate that there may be 30 or more additional living species that we are not yet confident to discriminate without molecular sequencing. Ammonia species live in most parts of the world between 62 degrees N (Faeroe Islands) and 55 degrees S (Strait of Magellan), where seasonal sea-surface temperatures are 4-10 degrees C and above. One estuarine species (A. veneta, T1) is cosmopolitan, euryhaline and eurythermic. Several species are widespread in one or two ocean regions (e.g., Atlantic and Mediterranean; South Pacific), whereas the majority are endemic to smaller areas (e.g., eastern Mediterranean; Caribbean-Gulf of Mexico). Eleven biogeographic "provinces" are recognized by cluster analysis of presence/absence records with the highest diversities in the Australian and northwest Pacific provinces with 18 and 19 species each). Levels of endemism in our "provinces" range between 0 (temperate Atlantic) and 44% (Australian).
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The distribution and abundance of live (rose Bengalstained) and dead infaunal foraminifera have been documented in short cores taken at four locations representing a narrow range of salinity settings in the mangrove swamps of the Setiu wetland, Terengganu, peninsular Malaysia. Cores were taken at mud-rich sites, two in the mid-swamp and two in the high swamp, from mainland-fringing mangrove swamps characterized by generally sandy substrates. Twenty-four taxa were recorded as live. Of these, two were restricted to the midswamp, eight were restricted to the high swamp, seven were restricted to shallow-infaunal depths (0–16 cm), and three were restricted to deep-infaunal depths (.16 cm). Thirteen taxa occurred both shallow and deep infaunally and 13 occurred at both high- and mid-swamp sites. Only six taxa, Ammobaculites exiguus, Bruneica clypea, Caronia exilis, Haplophragmoides wilberti, Siphotrochammina lobata, and Trochammina inflata were found live in all four cores. The down-core patterns of foraminiferal data in high swamp core SET10 SET1, high-swamp core SET09 TR2 15A and mid-swamp core SET09 TR3 7A are not significantly impacted by deep-infaunal contribution, down-core taphonomic loss, or bioturbation. This suggests that all three cores could record sea-level changes. In contrast, mid-swamp core SET 09 TR1 7A exhibits significant enrichment of down-core assemblages by deep-infaunal foraminifera and extensive down-core taphonomic loss of tests, thus precluding its use for sea-level reconstructions. It is arguable whether the basis for down-core sea-level reconstructions should be surface samples of transects across the mangrove swamp because an average of only 7% of the total number of live foraminifera in the four cores occurs in the 0–2 cm depth interval; most of the standing crop occurs in the 0–16 cm interval. However, because all abundant taxa occur both shallow (,16 cm) and deep (.16 cm) infaunally and assemblages in the 0–2 cm interval are very similar to those in the 0–16 cm interval, down-core sea-level reconstructions based on 0–2 cm surface samples, with a calculated error range of ca ±18 cm, could be attempted. Thus, it is possible that a sea-level signal could be preserved in foraminiferal assemblages from the mangrove swamps of Setiu, Malaysia, albeit with a relatively low resolution.
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Submitted in fulfilment of the requirements for the degree of Magister Scientiae in the Faculty of Science at the Nelson Mandela Metropolitan University.
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Foraminiferal assemblages were used to investigate the nature of sedimentation on the technically active Poverty continental margin (PCM) of New Zealand. Recent research around the world has been focused on understanding the sedimentary functioning of small mountainous rivers to the global sediment budget, and this study is part of a greater effort to define the processes that link sediment source and sink of such a system in New Zealand. Fifty-five surface samples from box, gravity, and multi-cores from the shelf and slope of the PCM were used to document the distribution of modern benthic foraminifera. Also, twenty samples from two gravity cores retrieved from Poverty Canyon, a hypothesized conduit of sediment to the deep ocean, were analyzed to evaluate the record of down-slope sediment transport. Seven biofacies, recognized by cluster analysis of benthic foraminiferal abundance data from surface and core samples, are strongly related to water depth and continental margin morphology: inner-shelf biofacies (26-43 m), shelf biofacies (∼30-130 m) (this biofacies contained all samples from a canyon-head core taken at 359-m water depth), outer-shelf biofacies (60-250 m), upper-slope biofacies (230-350 m), shallow lower-slope biofacies (870-1255 m), Lachlan Anticline biofacies (40-63 m on the PCM shelf), and a mid-canyon thalweg biofacies from a core taken at 891-m water depth. Foraminiferal assemblages of the Lachlan Anticline biofacies are characterized by the largest foraminifera (mostly innerand mid-shelf species), the most diverse assemblages, and the highest percentage of reworked planktonic tests in the dataset. Many planktonic and benthic specimens have probably been derived from the outcropping Miocene-Pliocene rock of the anticline. A high percentage of reworked (fossil) planktonic foraminifera at the mouth of Poverty Bay likely results from sediments shed from rapidly uplifting Plio-Pleistocene strata within the Waipaoa River drainage basin. Assemblages throughout the canyon-head (359 m) and midcanyon (891 m) cores from Poverty Canyon contained higher percentages of shallower-water indicator taxa than other samples at similar depths outside the canyon, thus supporting the hypothesis that Poverty Canyon is channeling sediment from the shelf and upper slope to the deep ocean. However, different patterns of down-core distributions between the canyon head and mid-slope thalweg sites indicate that the nature of sedimentation varies down canyon. Abundances of shallower-water foraminifera suggest that shelf taxa are being supplied from a more consistent source to the canyon head, while shelf and upper-slope taxa are more variably supplied to the deeper-canyon thalweg. The effects of bioturbation appear to be greater in the canyon head.
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Globally, one of the two most common shallow-marine and estuarine foraminiferal genera is Ammonia. Over the past 50 years, the majority of workers have identified specimens in this genus as belonging to just 1–3 cosmopolitan species – A. beccarii, A. tepida and A. parkinsoniana. This has been partly because of the problems of discriminating the Ammonia species based entirely on shell morphology and partly because of a 1974 laboratory study that claimed to have shown that all morphologies were merely ecophenotypic variants of one species – a conclusion that molecular studies have proven to be unequivocally wrong. In this study we recognize, describe and figure sixty-seven living species and infraspecies of Recent Ammonia and two closely-related genera (Acarotrochus, Pseudoeponides) from around the world and summarize their ecological and biogeographic distribution. Twenty-six species and two subspecies are recognized by DNA sequencing and shown to be morphologically distinguishable. A further 39 morphospecies and one subspecies, that have not yet been sequenced, have sufficiently distinct morphology to be recognized. Canonical variates analysis using 42 measured or assessed morphological characters shows that the majority of these species can be readily discriminated by their test morphologies, although a few of the less-ornamented molecular species are verging on being pseudocryptic. Molecular sequencing of the type species of Challengerella (C. bradyi) and Helenina (H. anderseni) places them within our Ammonia clade. Here we continue to recognize the morphologically highly distinct genera Pseudoeponides (subjective senior synonym of Helenina) and allied Acarotrochus. Twenty new species or subspecies are described (molecular T types in brackets): Ammonia abramovichae (T8), A. akitaae, A. aoteana australiensis (T5A), A. arabica (T26), A. ariakensis quiltyi, A. buzasi (T11), A. fajemilai, A. goldsteinae, A. goodayi, A. haigi (T25), A. hattai, A. jorisseni (T23), A. justinparkeri, A. kitazatoi (T10), A. morleyae (T12), A. shchedrinae, A. turgida almogilabinae (T22M), Acarotrochus lippsi, Pseudoeponides hottingeri and P. dubuissoni. Aneotype is designated for A. veneta (Schultze 1854) (T1).We recognize 67 Ammonia and related taxa in this study but speculate that there may be 30 or more additional living species that we are not yet confident to discriminate without molecular sequencing. Ammonia species live in most parts of the world between 62 °N (Faeroe Islands) and 55 °S (Strait of Magellan), where seasonal sea-surface temperatures are 4–10° C and above. One estuarine species (A. veneta, T1) is cosmopolitan, euryhaline and eurythermic. Several species are widespread in one or two ocean regions (e.g., Atlantic and Mediterranean; South Pacific), whereas the majority are endemic to smaller areas (e.g., eastern Mediterranean; Caribbean-Gulf of Mexico). Eleven biogeographic “provinces” are recognized by cluster analysis of presence/absence records with the highest diversities in the Australian and northwest Pacific provinces with 18 and 19 species each). Levels of endemism in our “provinces” range between 0 (temperate Atlantic) and 44% (Australian).
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Elphidium macellum is a benthic foraminifer commonly found in the Patagonian fjords. To test whether its highly variable morphotypes are ecophenotypes or different genotypes, we analysed 70 sequences of the SSU rRNA gene from 25 specimens. Unexpectedly, we identified 11 distinct ribotypes, with up to 5 ribotypes co-occurring within the same specimen. The ribotypes differ by varying blocks of sequence located at the end of stem-loop motifs in the three expansion segments specific to foraminifera. These changes, distinct from typical SNPs and indels, directly affect the structure of the expansion segments. Their mosaic distribution suggests that ribotypes originated by recombination of two or more clusters of ribosomal genes. We propose that this expansion segment polymorphism (ESP) could originate from hybridization of morphologically different populations of Patagonian Elphidium. We speculate that the complex geological history of Patagonia enhanced divergence of coastal foraminiferal species and contributed to increasing genetic and morphological variation.
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Two preliminary surveys (one during the dry season and one during the wet season) of the ostracod fauna of Verlorenvlei (Western Cape) are presented. Fifteen species were found; two are reported for the first time from Africa. Various species are indicative of slightly saline to even hypersaline conditions. The morphology and ecology of the various species are briefly discussed, in order to allow future palaeo-environmental reconstructions based on ostracod fossils from this locality.
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Illustrates vertical ranges of marsh foraminifera, with the fauna nearest the higher water level producing the best accuracy for relocating former sea levels. Low marsh (zone II) is not a good indicator. It is now possible to accurately determine former sea levels in the Bay of Fundy, at least for the last 4000yrs.-from Authors
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