Characterization of zoobenthos associated with the macroalga Colpomenia sinuosa in the rocky coast of Barbasquillo, Manabí, Ecuador

Caracterización del zoobentos asociado a la macroalga Colpomenia sinuosa en el litoral rocoso de Barbasquillo, Manabí, Ecuador

Mendoza, Nicole; Palma, Anthony; Quijije, Luber

Nicole Mendoza

nicolemence19@gmail.com

Universidad Eloy Alfaro de Manabí Ecuador

Anthony Palma

e1350636914@live.uleam.edu.ec

Universidad Eloy Alfaro de Manabí Ecuador

Luber Quijije

luber.quijije@uleam.edu.ec

Universidad Eloy Alfaro de Manabí Ecuador

ACTA OCEANOGRAFICA DEL PACÍFICO

Instituto Oceanográfico y Antártico de la Armada, Ecuador

ISSN: 1390-129X

ISSN-e: 2806-5522

Periodicity: Semestral

vol. 5, no. 2, 2023

acta.oceanografica@inocar.mil

Received: 11 March 2023

Accepted: 23 May 2023

URL: http://portal.amelica.org/ameli/journal/648/64844286484428004/

Non-profit publishing model to preserve the academic and open nature of scientific communication

ePub generated from XML JATS4R

Abstract: The zoobenthos represents one of the most diverse and exclusive groups of the rocky intertidal zone, characterized by the permanent presence of many taxa and families. The objective of this work is to characterize the zoobenthos associated with the macroalga Colpomenia sinuosain the rocky coast of Barbasquillo beach, identify the organisms present down to the lowest taxon, determine the abundance, diversity and relate the zoobenthos present with the abiotic factors (temperature, pH and salinity) of the area. The study area was monitored twice a month, with an interval of 15 days, from May to October 2022. A 5 x 10 m band transect was used, located in the meso littoral zone of Barbasquillo beach. The salinity, pH and temperature of the seawater in the study area varied during the monitoring months, presenting values of 30.82 ± 2.52 UPS; 7.45 ± 0.19 NBS and 24.34 ± 0.49°C respectively. The zoobenthic community associated with C. sinuosa was 2450 individuals, represented by 12 species, 21 genera, 17 families and 9 classes, belonging to 5 phyla. Mollusks were the most abundant group with 76.98%, followed by arthropods (19.55%), annelids (3.10%), echinoderms (0.29%) and chordates (0.08%), the most abundant species being Columbella rusticoides. In the study area there is a medium diversity and high dominance. In general, no clear relationships were observed between the environmental parameters considered in this work and the changes in the zoobenthic communities recorded.

Keywords: Abundance, Columbella rusticoides, Diversity, Physicochemical parameters, Rocky intertidal zone.

Resumen: El zoobentos representa uno de los grupos más diversos y exclusivos de la zona intermareal rocosa, caracterizada por la presencia permanente de muchos taxones y familias. El objetivo de este trabajo es caracterizar el zoobentos asociado a la macroalga Colpomenia sinuosa en el litoral rocoso de la playa Barbasquillo, identificar los organismos presentes hasta el taxón más bajo, determinar la abundancia, diversidad y relacionar el zoobentos presente con los factores abióticos (temperatura, pH y salinidad) de la zona. Se realizó dos monitoreos al mes en la zona de estudio, con un intervalo de 15 días, desde mayo hasta octubre del 2022. Se usó una transecta en banda de 5 x10 m situada en la zona meso litoral de la playa Barbasquillo. La salinidad, pH y temperatura del agua de mar de la zona de estudio varió durante los meses de monitoreo, presentó valores de 30,82 ± 2,52 UPS; 7,45 ± 0,19 NBS y 24,34 ± 0,49°C respectivamente. La comunidad zoobéntonica asociada a C. sinuosa fue de 2450 individuos, representados por 12 especies, 21 géneros, 17 familias y 9 clases, pertenecientes a 5 phyla. Los moluscos fue el grupo más abundante con el 76,98%, seguido de los artrópodos (19,55%), los anélidos (3,10%), equinodermos (0,29%) y los cordados (0,08%), la especie más abundante fue Columbella rusticoides. En la zona de estudio existe una diversidad media y una alta dominancia. En general, no se observaron relaciones claras entre los parámetros ambientales consideradas en este trabajo y los cambios en las comunidades zoobentónicas registradas.

Palabras clave: Abundancia, Columbella rusticoides, Diversidad, Parámetros fisicoquímicos, Zona intermareal rocosa.

Introduction

The rocky coastline consists mainly of rocks exposed to wave and tidal action. It is one of the most physically extreme environments on Earth. The various organisms (invertebrates and vertebrates) that inhabit rocky shores have adapted to this environment according to certain events that condition the distribution of species, such as physicochemical factors (climate, temperature, waves, light, tides, salinity and pH) and biological factors (predator pressure, competition for space and food) (Dauer, 1993; Saiz, 1997).

Zoobenthos is one of the most important links in the transfer of matter and energy in global ecosystems (Vásquez et al., 2010). Benthic animals depend on substrates to attach to the surface or sediments, as well as to obtain food or nutrients (Sebens, 1991). The benthic fauna represents one of the most diverse and exclusive groups of the rocky intertidal zone, characterized by the permanent presence of many taxa and families (Lagos Tobias et al., Albierno, 2013). The benthic community is classified according to size: microbenthos (< 0.1 mm), meiobenthos (> 0.1 mm to < 1 mm) and macrobenthos (> 1 mm), and according to habitat type: infauna, such as animals living within the substrate and epifauna living on the surface (Vegas, 1980).

Macrophytic algal communities characterize rocky intertidal and subtidal landscapes of the planet, which contribute to enriched habitats for small invertebrate groups, especially for benthic animals, which compose the main substrates in which organisms develop (Arroyo, 2002). Sediments play a critical role in the aquatic environment because they reflect what is happening in the water column (Lanza, 1980). Colpomenia sinuosa is widely distributed in the tropical and subtropical oceans of the world (Wynne and Norris, 1976). The species attaches to rocky or sandy bottoms, often in shallow intertidal areas (Ramirez Maria and Rojas Gloria, 1991).

Arroyo (2002) mentions that zoobenthos is an important element in marine systems. In rocky areas, meiobenthic communities are associated with algae and form associations with macrobenthic organisms (Branch, 1974). The productivity of the benthic fauna influences the distribution and abundance of other organisms. (Arroyo, 2002; Neira et al., 2001). As food at trophic levels, they constitute an important resource for a large number of organisms, since they form a fundamental link between macrobenthos and primary producers (Coull and Wells, 1983; Gibbons, 1988; Holbrook and Schmitt, 1996; Holbrook et al., 1997; De Troch et al., 1998; Schmid-Araya and Schmid, 2000; Neira et al., 2001).

Coull and Chandler (1992), indicate that zoobenthos serve as potential indicators of anthropogenic disturbances, as they can sense changes in marine ecosystem variables (Yánez, 2015; Mirto and Danovaro, 2004; Semprucci et al., 2016). These activities include sewage, drainage, industrial disposal and dredging, oil spill, and construction activities in coastal areas. Consequently, these activities affect benthic organisms, as their habitats are the major reservoirs of these wastes (Pérez-Peña, M., 1994). Bouwman et al. (1984) report that the structure of benthic communities near sources of organic pollution is so strongly affected that they tend to disappear, with a decrease in diversity and an increase in the number of more tolerant species; and an abundance considered normal is observed as the distance from the affected area increases.

Currently there are few works concerning the characterization of zoobenthos, even in coastal areas of the country where there is no evidence of any work associated with it, so the objective of this work is to characterize the zoobenthos associated with the macroalgae Phaeophyceae Colpomenia sinuosa (Mertens ex Roth) Derbès and Solier, 1851 in the rocky coast of Barbasquillo beach, identify the organisms present down to the lowest taxon, determine the abundance and diversity, and relate the zoobenthos present with the abiotic factors (temperature, pH and salinity) of the area.

Materials and methods

Study area

The study was carried out in the rocky intertidal zone of Barbasquillo beach (0º56'35" S - 80º 44'45" W). The locality is located west of the city of Manta, in the province of Manabí, with an extension of approximately 495 m of beach (Fig. 1). The area has a tropical climate, with air temperatures ranging from 25 to 29 °C (Ecostravel, 2020), while water temperatures in the area vary between 23 and 27 °C (INOCAR, 2022). Rainfall is concentrated between December and April.

Figure 1.
Location of sampling site, between two breakwaters of Barbasquillo beach.

Field phase

Two monthly monitoring surveys were conducted in the study area, with an interval of 15 days, from May to October 2022. Sampling was carried out at low tides, using the tide table (INOCAR, 2022).

Data on physical and chemical factors, salinity, pH (logarithmic scale or NBS), and temperature were recorded with MGR multiparameter equipment, model 4 in 1. To determine the abundance and diversity of individuals located in the specimens of Colpomenia sinuosa, the method proposed by Mostacedo and Fredericksen (2000) was adapted according to the needs of the area. Thus, a 5 x 10 m band transect was used, located in the meso littoral zone of Barbasquillo beach, with a 1 m quadrant. in 5 points, located at its ends and in the central part of the transect (Fig. 2). Ten algae samples were taken per quadrant, for a total of 50 samples within the transect. Once the samples were collected, they were placed in transparent trays with 4% formaldehyde diluted in seawater and buffered with sodium tetraborate (Flores-Leiva, et al., 2010).

Figure 2
a) Sampling area, b) Transect and quadrats.

Laboratory phase

A LABOMED microscope, model Lx 400, with magnifications of 4X, 10X, 40X and 100X, was used to count the individuals found in the Colpomenia sinuosa specimens. For the identification of the organisms, the keys of León González et al. (2021), del Pilar Ruso et al. (2014), Ortiz M. and Jimeno A. (2001), Fischer W. et al. (1995) were used. Each organism was photographed using Viboton brand digital microscope, model VB-11. With the photographs, it is expected to develop a manual for the identification of zoobenthic organisms.

Statistical Analysis

To determine the diversity and abundance of zoobenthos, the corresponding diversity indices were taken.

Shannon-Weaver Index.

To determine the diversity of zoobenthos associated with the algae, the Shannon-Weaver Index, "H', is used, where it will have an interval between zero when there is only one species (low abundance), and when it approaches 5, it means that all species are represented by the same number of individuals (high abundance), in most natural ecosystems it varies between 0.5 and 5, although its normal value is between 2 and 3; values lower than 2 are considered low and higher than 3 high (Magurran 1988, Moreno 2001).

Where: S= number of species (species richness), Pi= proportion of individuals of species i to the total number of individuals (i.e. the relative abundance of species i): Ni/N, ni= number of individuals of species i, N= number of all individuals of all species

Simpson's Index.

This index was proposed by Simpson (1949), it is one of the most used by researchers, because it allows measuring the species dominance (λ), while the diversity index (D), would be the complementary value of λ, or D=1- λ. The value of λ oscillates between 0 and 1, if the value of λ gives 0, it means infinite diversity, if the value of λ gives 1, it means that there is no diversity and that the dominance of a single species is absolute.

Where: S= is the number of species, N= is the total number of organisms present (or square units), n= is the number of specimens per species.

Table 1 proposed by Magurran (1988) and Krebs (1985) was used to interpret the values of the Shannon-Weaver index and Simpson's index in this study:

Table 1

Values for the Shannon-Weaver Index (according to Magurran, 1988) and Simpson's Index (according to Krebs, 1985).

Pearson correlation

To estimate the relationship between zoobenthos and abiotic factors, the Pearson correlation coefficient was applied between the quantitative variables of temperature, pH and salinity versus the zoobenthic community present in the area. In addition, to determine if the relationship is statistically significant between both variables.

Results

Physical and chemical factors

The physicochemical parameters of the seawater in the rocky intertidal zone of Barbasquillo varied during the months of monitoring and registered minimum and maximum values, with an average salinity of 30.82 ± 2.52 UPS (26.3 to 34.4 UPS); pH 7.45 ± 0.19 (7.22 to 7.76) and temperature 24.34 ± 0.49 ± 0.49 (7.00 ± 0.00).

°C (23.6 to 25.2 °C) respectively (Fig. 3). Salinity showed a high variation in the sampling area, possibly due to direct discharges from various sewage emission sources near the rocky intertidal zone where the study was conducted.

Figure 3
Bimonthly values of salinity temperature and pH in the monitoring

Taxon richness and density

A total of 2450 organisms belonging to 17 families were identified (Table 2). Species richness varied between 8 and 14, with the highest value observed in the 1st monitoring in September (Fig. 4). During the study, the presence and dominance of Columbella rusticoides snails of the Columbellidae family was observed at all levels, except in May 2, which presented a density of 23 org/5m. representing 13.37% of the total zoobenthos (Fig. 5).

Table 2

Component taxonomic groups of zoobenthos in the Barbasquillo rocky shore during May 2022 - October 2022.

Figure 4
Specific richness of zoobenthos in the intertidal zone of Barbasquillo 202

Figure 5.
Percentage representation of the zoobenthic species present in the months of monitoring in the intertidal zone of Barbasquillo.

The highest densities of C. rusticoides were found in May 1, which presented 47 org/5m. (58.75%) showing its maximum values in October 1 (178 org/5m. ; 55.45%) and minimum in June 1 (27 org/5m2; 43.55%) (Fig. 5). Significant differences (P=0.006) were detected between the population densities of the aforementioned species and the months sampled. On the other hand, Hyale sp. corresponding to the Hyalidae family was the second dominant group, the third group was the Cerithiidae family, whose representative species was Cerithium litteratum, both groups did not present significant differences (P=0.372; 0.083) in the population densities of each family. On the other hand, the presence of a single organism was recorded in the following species: Lepidochitona sp.; Strongylocentrotus purpuratus. Malacoctenus tetranemus; Gobiesox adustus; Dolabrifera nicaraguana and Phascolosoma agassizii (Fig. 6).

Figure 6
Zoobenthic species associated with Colpomenia sinuosa: a) Columbella rusticoides; b) C. deshayesi; c) Cerithium litteratum; d) C. gallapaginis; e) Turbo sp;, f) Turbonilla sp.g) Dolabrifera nicaraguana; h) Apohyale prevostii; i) Hyale sp.; j) Alpheus sp.; k) Xanthias sp.; l) Strongylocentrotus purpuratus; m) Ophiocoma sp.; n) Mytella guyanensis; o) Ischnochiton sp.; p) Lepidochitona sp.; q) Malacoctenus tetranemus; r) Gobiesox adustus; s) Nereis sp.; t) N. succinea; u) Phascolosoma agassizii.

Total zoobenthos recorded during the monitoring months did not follow a sustained trend in density, showing about 388 org/5m2 (27.71 ± 37.10) during September during the 1st monitoring and a low of 62 org/5m2 (13.13 ± 12.49) in June during the 2nd monitoring (Figure 7 and Table 3).

Figure 7.
Variation of zoobenthos density in Barbasquillo during the sampling months.

Table 3

Mean and standard deviation of zoobenthos density recorded in the monitoring months

Diversity

The Shannon-Weaner index and Simpson index showed little variation (Fig. 8). For the Shannon-Weaner index, the minimum value (1.26 = low diversity) was observed in the 2nd monitoring in May, while the maximum value (1.92 = medium diversity) occurred in the 1st monitoring in September. For Simpson's index the minimum value (0.55 = low dominance) was observed in the 2nd monitoring in May and the maximum (0.81 = high dominance) was evidenced in the 1st monitoring in September. There were no significant differences in both indexes (P= 0.285; 0.340).

Figure 8.
Values of the Shannon-Weaver and Simpson diversity and abundance indices present in the zoobenthos.

Relationship between diversity indices and abiotic factors

The Shannon-Weaner and Simpson indices were related to salinity, pH and temperature, showing that there was no significant correlation (P>0.05) between the variables described (Fig. 9).

Figure 9.
Relationship of the value of Shannon-Weaner and Simpson's diversity indices with salinity (a and b), pH (c and d) and temperature (e and f) of seawater.

The area comprising the rocky coast of Barbasquillo presented an average temperature of 24.34 ± 0.49, the months with the lowest temperature were from June to October 2022. Hurtado Gualán et al., (2016) mention that during the dry season, the territorial waters of southern Ecuador are cold, the temperature varies between 22 to 27 °C. During this season (June-November) the Humboldt current transports deep water masses from the south of the continent to Ecuador (Cucalon, 1989). Salinity showed a high variation in the sampling area, with an average value of 30.82 ± 2.52 UPS. In equatorial surface waters, salinity is between 33.8 and 35.1 UPS (De Morán et al., 1988), which does not contrast with the salinity values obtained, possibly due to direct discharges from various sources of sewage emissions near the rocky intertidal zone where the study was carried out (Pech et al., 2007). The pH presented a value of 7.22 to 7.66, which is in agreement with Vaca et al., (2022) who recorded values in the rocky intertidal zones of the San Lorenzo - Salinas beach between 7 and 8.5 off the coast of Ecuador.

The zoobenthic community associated with C. sinuosa in the rocky coast of Barbasquillo was 2450 individuals, represented by 12 species, 21 genera, 17 families and 9 classes, belonging to 5 phyla. Mollusks were the most abundant group with 76.98%, followed by arthropods (19.55%), annelids (3.10%), echinoderms (0.29%) and chordates (0.08%). Of all the biota inhabiting the rocky coasts, mollusks are recognized as zonation indicators (Bandel and Wedler, 1987) characterized by their resistance to environmental variables (Flores, 1973). The taxa composition of the benthic fauna in the present study coincides with the work of Cruz (2013), who mentions that the benthic fauna in Manta Bay was represented by 41 zoobenthic species, distributed in 6 phyla, of which the phylum mollusca was the most abundant with 31 species, representing 75% of the total richness of the organisms found.

The rocky intertidal coast is a highly heterogeneous environment that supports a variety of life forms that propagate in specific ways and follow vertical zonation patterns (Underwood, 1981). Castro and Huber (2003) indicate that the mesolittoral zone is the transition area between the supra- and infralittoral zones, and that there are physical and biological factors that alter this area, with physical factors such as desiccation and sunlight conditioning the number of species in the supralittoral zone, while biological factors such as predation and competition for space are limiting for the number of species in the infralittoral zone.

Arthropods represented 19.55%, of which 80% of this taxon belongs to the amphipods of the family Hyalidae, amphipods in Ecuador are little studied and no specific work has been done on this group in the country (Ortiz et al., 2004). There was no scientific information on amphipods on rocky substrates present on the Ecuadorian coast. However, Rodríguez (2019) reported the presence of amphipods on sandy beaches in the province of Santa Elena (Chipipe) and Guayas (General Villamil and Data de Posorja).

The annelids located in third place of representativeness (3.10%) as results of the present work (rocky intertidal zone), is close to that reported by Villota (2014) in the Marine Coastal Faunal Production Reserve Puntilla de Santa Elena "REMECOPSE", in the rocky intertidal zone of 4 points: Punta Carnero (1.9%), La Lobería (2.2%), La Chocolatera (4.4%) and Shitbay (0.4%). As for echinoderms (0.29%), they do not coincide with the work of Villota (2014) located in the same study site: Anconcito (1.6%), Punta Carnero (15.6%), La Lobería (32.1%), La Chocolatera (30.5%) and Shitbay (14.6%).

Chordates represented 0.08%, however, no scientific literature was found developed in the rocky intertidal zone of the Ecuadorian coastal profile, so the current results cannot be contrasted. However, Castellanos et al. (2010) and González et al. (2012) reported for Colombia and El Salvador, respectively, the families Gobiesocidae and Labrisomidae, and state that the presence of these two families may be related to barriers that limit the movement and exchange of species and therefore prevent faunal homogenization.

The diversity of zoobenthos in this study according to the Shannon-Weaner index was 1.6 ± 0.22 which corresponds to medium diversity according to Magurran (1988), and the values for Simpson's index was 0.7 ± 0.08, which indicates high dominance according to Krebs (1985). A possible explanation for this according to Brattström (1985) is that mesolittoral and supralittoral coastal areas are generally subject to continuous emersion, and only species adapted to them can resist the effects of wind, waves and desiccation. Duplisea and Drgas (1999) indicate that the presence of benthic fauna can be affected by the type of habitat and influenced by the nature of the substrate, which will determine the lifestyle of the species found in the ecosystem, including Gray and Elliot (2009) add that complex habitat architecture can reduce the impact of water currents on individuals and allow for greater abundance. It should be noted that all changes in the biodiversity of the marine benthos can generate a response to pressures on the ecological balance (Pearson, 1981).

When the environment is altered, opportunistic species emerge to occupy the spaces left by other species (Cornejo, 2006). Pech et al, (2007) show that the change in salinity due to the entry of fresh water constitutes a potential element in the distribution of diversity and abundance of zoobenthic species. In other words, the freshwater input from wastewater in the study area could be altering the benthic fauna, favoring the development of organisms adaptable to these changes. Giere (2008) points out that the pH of zoobenthos populations living in oceans or estuaries is not particularly important because the alkalinity of seawater acts as a "buffer" so there is no pH fluctuation. It has been observed that temperature does not inhibit the presence of zoobenthos, but according to Giere (1933) it can affect it, especially in areas subject to tidal influence. Boyd (2001) indicates that heat penetrates the water surface and warms the surface layer faster than the bottom layer. These temperature changes lead to control of the type and abundance of food, biological alterations and environmental changes.

Conclusions

It is observed that in the rocky coastal area of Barbasquillo, Manta, Manabí-Ecuador, there are no studies of the zoobenthos associated with the seaweed C. sinuosa, or of any relationship with the environment, for this reason it is not possible to make comparisons of zoobenthic communities, so the study will help to support the knowledge of the diversity and abundance of zoobenthos present in the area.

In the present work, during the months of sampling located in the rocky coast of Barbasquillo between May-October 2022, an average of salinity 30.82 ± 2.52 UPS; pH 7.45 ± 0.19 and temperature 24.34 ± 0.49 °C were obtained. A total of 21 genera were recorded, of which the most abundant species was Columbella rusticoides. There is medium diversity and high dominance in the study area. In general, no clear relationships were observed between the environmental parameters considered in this work and the changes in the zoobenthic communities recorded. In this sense, bioassay studies of the species identified in the area and the controlled variables are needed to recognize possible biological indicators in these environmental conditions, as well as to relate the diversity and abundance of zoobenthos to seasonal or anthropogenic changes.

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