Distribution of Benthic Foraminifera in the
Marine Estuary of the Guadalquivir River
(SW Spain): A Preliminary Report
María Luz González-Regalado1, Berta Carro1, Marta Arroyo1, Francisco Ruiz1,3,7*, José Borrego1, Manuel Abad2, Tatiana Izquierdo2, Josep Tosquella1, María Isabel Prudencio3, María Isabel Dias3, Rosa Marques3, Verónica Romero1, Joaquín Rodríguez Vidal1,7, Luis Miguel Cáceres1,7, Paula Gómez1,7, Antonio Toscano1,7, Guadalupe Monge4, María Isabel Carretero4, Juan Manuel Campos5,7, Javier Bermejo5,7 and Edith Xío Mara García6
1Departamento de Ciencias de la Tierra, Universidad de Huelva, Spain
2Universidad de Atacama, Chile
3Instituto Superior Técnico, Universidad de Lisboa, Portugal
4Departamento de Cristalografía, Universidad de Sevilla, Spain
5Departamento de Historia, Universidad de Huelva, Spain
6Centro Universitario de Tonalá, Universidad de Guadalajara, México
7Centro de Investigación en Patrimonio Histórico, Universidad de Huelva, Spain
Submission:February 09, 2019; Published: February 15, 2019
*Correspondence author: Francisco Ruiz, Departamento de Ciencias de la Tierra, Universidad de Huelva, Instituto Superior Técnico, Universidad de Lisboa. Avda. Tres de Marzo, s/n; CP 21071-Huelva, Spain
How to cite this article:María L G R, Berta C, Marta A, Francisco R, José B, et al. Distribution of Benthic Foraminifera in the Marine Estuary of the
Guadalquivir River (SW Spain): A Preliminary Report. Oceanogr Fish Open Access J. 2019; 9(2): 555759. DOI: 10.19080/OFOAJ.2019.09.555759
Three zones are differentiated in the marine sector of the Guadalquivir estuary (SW Spain), according to a multidisciplinary analysis (water, sediment, foraminifera). Both salinities and pH increase from the innermost areas (zone 1: Ammonia tepida) to the mouth (zone 3: Ammonia beccarii), with an intermediate zone 2 (Ammonia beccarii-Triloculina trigonula). Both density and diversity are low to very low, except near the transition between zones 2 and 3. Planktonic foraminifera decrease sea Ward from zone 1 to zone 3.
Benthic foraminifera are among the main environmental markers in coastal areas. The distribution of these microorganisms is conditioned by diverse physical-chemical parameters of the waters (salinity, dissolved oxygen, pH), as well as by the characteristics of the substrate where they live (granulometry, geochemistry) [1-3]. Its abundance and diversity can be altered by changes in the dynamics of the environment, erosion of the bottom or anthropic contamination, among other factors [4,5]. In southwestern Spain, several studies have analyzed the spatial distribution of benthic foraminifera in the different sedimentary environments of three estuaries (Guadiana, Piedras and Tinto-Odiel) [6-8].
In a synthetic way, the main species of each of them are the following:
a) High salt marsh: Trochammina inflata.
b) Low salt marsh: Entzia macrescens.
c) Channel margin: Ammonia inflata and Astrononion stelligerum.
d) Marine channel: Ammonia beccarii and Quinqueloculina spp.
In this short note, we present the first data about the benthic foraminifera of the Guadalquivir river (SW Spain). The data obtained are related to several parameters of both waters and sediments in which they have been found.
The Guadalquivir river is the main fluvial stream of southwestern Spain (657 km). This river has a very irregular regime, with an annual average of 185 m3s-1 and a maximum of more than 1,000 m3s-1 [9,10]. These flows are partially controlled by several dams located upstream. The tidal regime is mesotidal and semidiurnal, with an average tidal range of 3.6 m . The marine estuary of the Guadalquivir River is constituted by the Doñana National Park (SW Spain), one of the most important
wetlands in southwestern Europe (Figure 1: 54,215 ha).
This Biosphere Reserve includes a rich variety of ecosystems
(freshwater ponds, dunes, cheniers, sandy ridges), with a wide
fluvio-tidal marshland (27,000 ha) drained by numerous ebbtide
channels. This complex inner scenario is protected by the
NW-SE elongated Doñana spit (Figure 1).
The field campaign was held in February 2017. The
physicochemical variables of water (pH, conductivity, redox
potential and temperature) were determined in situ at
three sampling points (Figure 1: A-B-C) by using portable
multiparameter equipment (CrisonMM40). The electrodes were
calibrated prior to sampling and tested between each sampling
point. Conductivity was transformed to salinity in the following
chapters, according to the data obtained in numerous points
of the studied area . Five sediment samples (Figure 1: 1-5)
were obtained with a Van Veen grab. These samples were stored
in labeled self-sealing plastic bags until further analysis in the
laboratory at 4ºC until they reached the laboratory, where they
were dried in an oven at 60ºC until constant weight was reached.
The particle-size distribution of the collected sediments was
studied using a Malvern Mastersizer 2000 (Malvern Instruments
Ltd., UK) belonging to the Department of Earth Sciences
(University of Huelva, Spain). Five sediment subsamples were
separated for micropaleontological analysis. Forty grams of
sediment were wet sieved through a 63 μm mesh sieve and
the residue was dried in an oven at 70 °C. All foraminifera
were picked from each subsample, with the calculation of the
percentages of both the benthic foraminiferal species and the
planktonic/ benthic index (P/B, in %).
In winter, conductivity values of this marine estuary are low
to very low, increasing from the most internal areas (1,817 μS;
salinity <1o/oo) to the mouth (7,624 μS; salinity: 3.50/00-6.4
0/00). These data coincide with those provided by previous
research (<50/00) . These waters are alkaline, with a rising pH
towards the sea (7.31-7.88). Eh (85.3-93.4 mV) and temperature
(13oC-14.6oC) increase in the same direction. Bottom sediments
of the innermost zone present similar percentages of sand and
silt (Figure 2: sample 1). Near the mouth, bioclastic sands are
dominant, with numerous fragments of molluscs, bryozoans
and echinoid spines, among others. Silt can become dominant in
some cases, coinciding with lower flow rates (Figure 2: sample
3) (Figure 2)
A total of 406 benthic foraminifera were collected from
the five samples (mean-M-: 81 individuals picked per sample),
belonging to 32 genera and 45 species. Suborden Rotaliina is
dominant in all samples (55.71%-75.76%; M: 66.36%), with
miliolids as main secondary component (18.18%-41.43%; M:
29.77%). This distribution is typical of normal marine lagoons,
estuarine channels or normal marine marshes [8,14]. The most
abundant species are Ammonia beccarii (3.03%-38.46%; M:
18.97%), Triloculina trigonula (5.13%-18.18%; M: 12.59%),
Quinqueloculina seminulum (0-10%; M: 6.05%), Quinqueloculina
vulgaris (0-10%; M: 6.05%) and Ammonia tepida (0-30.03%;
M: 6%). Sixteen benthic species are present in an isolated
sample, such as A. tepida (sample 1: 30.03%). Density of these
microorganisms is low to very low (<1 individual/gram-4
individuals/gram), with a very low number of individuals in
the innermost areas, at the confluence with a tributary channel
(sample 1). In other estuaries, this scarcity or even the absent of
this group has been observed in the main channels subjected to
a strong erosion of the bottom or high hydrodynamic gradients
. Diversity is low in most samples (13-19 species), with a
remarkable increase in sample 4 (34 species) (Table 1).
Abundance (in %), density and diversity of benthic foraminifera and evolution of the P/B index (in %).
Planktonic foraminifera show a surprising pattern, since they
gradually diminish towards the sea from sample. The highest
values were found in the innermost sample (P/B: 29.2%), while
this group drops by 18% near the mouth. These microorganisms
are introduced in suspension into the estuary by the tidal flows
 and are deposited in the bottom when the speed of tidal
currents decreases. The low values detected near the mouth
may be due to a selective destruction of its thin shells in relation
to the thicker shells of most benthic foraminifera, owing to the
strong bottom currents of this area .
Benthic foraminiferal distribution on the marine estuary of
the Guadalquivir river allows to differentiate three zones. There
is a gradation from the most internal sectors (Zone 1) to the
mouth (Zone 3).
Zone 1 (Ammonia tepida zone): This zone is characterized
by the lowest salinity (<1o/oo) and pH values (7.3). In its
silty-sandy bottom sediments, benthic foraminifera are very
scarce and poorly diversified, with Ammonia tepida (30%) and
Trigonulina trigonula (>18%) as main species. Ammonia tepida
is a very common euryhaline species in estuarine environments,
and can survive over a broad range of temperatures and seasonal
regimes [18,19]. This zone presents the highest P/B values
Zone 2 (Ammonia beccarii-Triloculina trigonula zone):
This intermediate zone is characterized by very low salinities
and an increase of the sandy contents in the bottom sediments.
Ammonia beccarii replaces Ammonia tepida as dominant
species, whereas the percentages of Triloculina trigonula
decrease seaward. Ammonia beccarii is better adapted than
Ammonia tepida to hydrodynamic stress conditions in estuarine
environments, such as those present in the main channels near
the mouths . The joint presence of Trochammina inflata and
Entzia macrescens indicates the erosion of adjacent salt marshes,
where these species are dominant .
Zone 3 (Ammonia beccarii zone): The Guadalquivir river
mouth presents both low densities (<2 individuals per gram)
and diversity (17 species). The foraminiferal assemblage is
dominated by Ammonia beccarii (<38%), together with several
species of Quinqueloculina (>19%) and Elphidium (14%). This
assemblage is typical of shallow marine shelfs and the marine
sectors of numerous estuaries [21,22]. Moreover, this energetic
area shows the lower P/B values (17.5%).
We thank Dr. Juan Antonio Morales (Universidad de Huelva,
Spain) for his help in collecting the samples. This work has
been carried out through the Project Study of the sediment
characteristics and the recent sedimentary record of the
Guadalquivir River Estuary (Port autority of Seville). Other funds
have come from the Andalusian Government (groups RNM-238,
RNM-276 AND RNM-293). It is a contribution to the Research
Center in Historical, Cultural and Natural Heritage (CIPHCN) of
the University of Huelva.
Sreenivasulu G, Praseetha BS, Daud NR, Varghese TI, Prakash TN, et al. (2019) Benthic foraminífera as potential ecological proxies for enviromental monitoring in coastal regions: A study on the Beypore estuary, Southwest coast of India. Marine Pollution Bulletin 138: 341-351.
Haller C, Smith CG, Hallock P, Hine AC, Osterman LE, et al. (2019) Distribution of Modern Salt-marsh Foraminifera from the Eastern Mississippi Sound, USA. Journal of Foraminiferal Research 49(1): 29-47.
González-Regalado ML, Ruiz F, Morales JA (1998) Relación entre submedios sedimentarios y los foraminíferos bentónicos del subsistema Carreras (Río Guadiana, SO de España). Boletín de la Real Sociedad Española de Historia Natural (Sección Geología) 94(1-2): 65-76.
Vanney JR (1970) L’hydrologie du Bas Guadalquivir. In: Consejo Superior de Investigaciones Científicas, Spain, pp. 175
Menanteau L (1979) Les Marismas du Guadalquivir. Example de transformation d’un pausage alluvial au cours du Quaternaire ré Thèse 3er cycle, Université Paris-Sorbonne, pp. 323.
Borrego J, Morales JA, Pendón JG (1993) Elementos morfodinámicos responsables de la evolución reciente del estuario bajo del río Guadiana (Huelva). Geogaceta 11: 86-89.
Bodelón OG, Bernués M, Baltanás A, Montes C (1994) Conductividad y salinidad en los ecosistemas acuáticos del Parque Nacional de Doñ Limnetica 10(2): 27-31.
Baldó F, Cuesta JA, Fernández-Delgado C, Drake P (2005) Efecto de la regulación del caudal del Río Guadalquivir sobre las características fisicoquímicas del agua y la macrofauna acuática de su estuario. Ciencias Marinas 31(3): 467-476.
Murray J (2006) Ecology and applications of benthic foraminifera. In: Cambridge University Press, US, pp. 426
Bonetti C, Eichler BB (1997) Benthic foraminifera and thecamoebians as indicators of river/sea gradientes in the estuarine zone of Itapitangui River-Cananéia/SP, Brazil. Anais da Academia Brasileira de Ciências 69(4): 544-563.
Costa S, Gutiérrez-Mas JM, Morales JA (2009) Establecimiento del régimen de flujo en estuario del Guadalquivir, mediante el análisis de formas de fondo con sonda multihaz. Revista de la Sociedad Geológica de España 22(1-2): 23-42.
Pascal P, Dupuy C, Richard P, Niquil N (2008) Bacterivory in the common foraminifer Ammonia tepida: Isotope tracer experiment and the controlling factors. Journal of Experimental Marine Biology and Ecology 359: 55-61.
Wu J, Liu C, Fürsich FT, Yang T, Yin J (2015) Foramifera as environmental indicators and qunatitative salinity reconstructions in the Pearl river estuary, southern China. Journal of Foraminiferal Research 45(3): 205-219.
Camacho SG, Moura DMJ, Connor S, Scott DB, Boski T (2015) Taxonomy, ecology and biogeographical trends of dominant benthic foraminifera species from an Atlantic-Mediterranean estuary (the Guadiana, southeast Portugal). Palaeontologia Electronica 18.1(17A): 1-27.
Kumar DN, Ganesh B, Karudu TK, Rao MJ (2012) A record on benthic foraminiferal abundance and distribution in Gosthani estuary, Bheemunipatnam, Andhra Pradesh. Indian Journal of Geo-Marine Sciences 41(5): 425-429.