Maya-Alvarado, B., Calva-Benítez, L.G., Granja- Fernández, R., Pérez-López, J., & López-Pérez, A. (2021). Feeding habits of Holothuria (Stauropora) fuscocinerea (Echinodermata: Holothuroidea) in a Mexican Pacific reef. Revista de Biología Tropical, 69(S1), 66-79. DOI 10.15517/rbt.v69iSuppl.1.46328 DOI 10.15517/rbt.v69iSuppl.1.46328 Feeding habits of Holothuria (Stauropora) fuscocinerea (Echinodermata: Holothuroidea) in a Mexican Pacific reef Brenda Maya-Alvarado1,2 Laura Georgina Calva-Benítez2 Rebeca Granja-Fernández3 Jessica Pérez-López2 Andrés López-Pérez2* 1. Programa de Maestría en Ciencias en Biosistemática y Manejo de Recursos Naturales y Agrícolas, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Av. Ing. Ramón Padilla Sánchez, Zapopan, Jalisco, México; [email protected] 2. Laboratorio de Ecosistemas Costeros. Departamento de Hidrobiología, Universidad Autónoma Metropolitana Unidad Iztapalapa, Av. San Rafael Atlixco, Col. Vicentina, Iztapalapa, Ciudad de México, México; [email protected], [email protected], [email protected] (*Correspondence). 3. Laboratorio de Ecología Marina. Centro Universitario de la Costa, Universidad de Guadalajara, Av. Universidad, Puerto Vallarta, Jalisco, México; [email protected] Received 01-VI-2020. Corrected 10-IX-2020. Accepted 07-X-2020. ABSTRACT Introduction: The importance of holothuroids in marine ecosystems is related to their feeding activities, which have been little studied in the eastern Pacific. Objective: To describe the feeding habits of the sea cucumber Holothuria (Stauropora) fuscocinerea and their bioturbation potential in La Entrega reef, México. Methods: The population size of H. (Stauropora) fuscocinerea was determined by means of four 20 x 4 m (320 m2) band transects, while the available sediment for the sea cucumbers and their feces were characterized in three stations (A-C) via granulometry and quantification of organic carbon and organic matter. Excretion rate was determined every 4 hr over a 24 hr period and the relationship between sea cucumber length and biomass and the excretion rate evaluated. Results: According to non-parametric permutation, ordination and percentage similarity analy- ses, sea cucumber feces mostly comprised a large proportion of small grains compared to the available sediment, indicating that H. (Stauropora) fuscocinerea is selective on grain size. Preliminary bioturbation potential of the species may reach up to 8.71 ± 0.17 kg day of sediment in the study area. Conclusion: The spatial distribution of H. (Stauropora) fuscocinerea in the study area is a product of its selective feeding activity, evidencing the preliminary importance of the species in the trophic dynamics of La Entrega reef. Key words: selectivity; distribution; food; bioturbation; sea cucumber. Holothuroids, commonly known as sea feeding activity and diet, they can bioturbate cucumbers, are conspicuous and abundant large amounts of sediments every year (i.e. invertebrates that contribute largely to the bio- Crozier, 1918; Bonham & Held, 1963; Bakus, mass of marine ecosystems (Hendler, Miller, 1973; Uthicke, 1999; Purcell, Conand, Uthicke Pawson & Kier, 1995). As a result of their & Byrne, 2016), contributing to important 66 Revista de Biología Tropical, ISSN electrónico: 2215-2075 Vol. 69(S1): 66-79, March 2021 (Published Mar. 30, 2021) chemical and physical processes on the sea- species, its commercial importance and the rel- floor, and promoting the continuous mixing evance of holothuroids for bioturbation in reef of the sediment particles (Thayer, 1983). Sea ecosystems, this study aims to: a) determine the cucumbers actively participate in the recycling feeding habits of H. (Stauropora) fuscocinerea of nutrients and organic matter within marine in a tropical reef in the Mexican Pacific, and b) ecosystems (Bakus, 1973; Calva-Benítez, address their bioturbation potential. With this 2002), including coral reefs (Goldberg, 2013; information, inferences can be made in terms Sheppard, Davy, Pilling & Graham, 2017). of its small-scale distribution, along with its Despite being conspicuous and abundant feeding selectivity and its contribution to sedi- in coral reefs around the world (Sheppard et ment bioturbation in a typical reef system of al., 2017), the study of their feeding habits the eastern tropical Pacific. and their importance in sediment bioturbation in tropical reefs has focused mostly on holo- thuroids from the Indo-Pacific (Yang et al., MATERIALS AND METHODS 2005; Bucol, Cadivida & Wagey, 2018; Rioja, Study area: The study was carried out at Palomar-Abesamis & Juinio-Meñez, 2020). La Entrega bay (15°44’34’’ N & 96°07’35’’ W), Those studies have highlighted the selective located in southwest end of the Gulf of Tehu- nature of the feeding habits of holothuroids, antepec, Oaxaca, México (Fig. 1). La Entrega as well as their capacity to remove large is a small (0.1 km2) embayment located on the amounts of sediment and the wide spatial and west side of Santa Cruz bay. The seafloor of La temporal variation that exists among species Entrega consists of marine carbonate sediment (Trefz, 1956; Glynn, 1965; Bakus, 1968, 1973; mixed with siliciclastic material derived from Uthicke, 1999; Mezali & Soualili, 2013; Bel- the basaltic highlands of the Copalita river bachir, Mezali & Soualili, 2014). Holothuria (Stauropora) fuscocinerea is basin (Estrada-Vargas, 2008). The center of among the most common and widely dis- La Entrega is largely covered by an approxi- tributed holothuroid in the Indo and eastern mately 4.3 ha reef framework that follows a tropical Pacific (Purcell, Samyn & Conand, southwest-northeast direction and reaches 12 2012; Solís-Marín et al., 2013; Cortés et al., m in depth (Glynn & Leyte-Morales, 1997). 2017). However, little is known about its The coral community is composed by 11 coral biology, abundance and distribution, feeding species, live coral cover comprises 76.58 % habits and generally, the role that this species of the reef area, while the framework is built plays in the ecosystem. To date, the only study mainly by Pocillopora spp. species (> 95 %), of the species in the region is limited to its followed by Pavona spp. and Porites pana- annual reproductive periodicity on the coast mensis (López-Pérez & López-García, 2008; of Oaxaca, México (Benítez-Villalobos, Avila- Cabral-Tena et al., 2020). Poveda, & Gutiérrez-Méndez, 2013). In the The southwestern portion of the reef cor- Mexican Pacific and the Gulf of California, sea responds to the reef flat (2-5 m in depth) and cucumbers such as Isostichopus fuscus (Herre- comprises most of the reef framework, while ro-Pérezrul & Chávez, 2005) and Holothuria the fore reef comprises ~ 30 % of the area. (Halodeima) inornata are regularly exploited While the former results of the interlocking of commercially and are currently under the pro- Pocillopora spp. colonies, the fore reef area tection of Mexican laws (SEMARNAT, 2019). is a transition zone where live coral cover On the other hand, H. (Stauropora) fuscoci- is severely reduced (~ 70 %) and branch- nerea, is of commercial importance in China, ing Pocillopora spp. and the massive corals Malaysia and the Philippines (Purcell et al., Pavona gigantea and Pavona varians coexist 2012), but lacks protection status in México. with the emerald coral P. panamensis, along Due to the paucity of information about the with sparse patches of sand and dead corals Revista de Biología Tropical, ISSN electrónico: 2215-2075, Vol. 69(S1): 66-79, March 2021 (Published Mar. 30, 2021) 67 Fig. 1. Sampling stations (A, B, C [experimental cages]) and zoning of La Entrega reef, Mexican Pacific. See text for information regarding sampling stations. (Glynn & Leyte-Morales, 1997; López-Pérez Fieldwork: The population density of H. & Hernández-Ballesteros, 2004) (Fig. 1). (Stauropora) fuscocinerea (Fig. 2A) in La La Entrega reef is habitat of several marine Entrega was determined during SCUBA div- invertebrates, including echinoderms (López- ing visual censuses, using four 20 x 4 m (320 Pérez et al., 2019). Among the echinoderm m²) belt transects. During January 2018, visual species, the sea cucumber H. (Stauropora) fus- census was conducted at two stations parallel cocinerea is mainly distributed in the fore reef to the coastline, called A and B, at a depth of transition zone between the reef flat and the 10 m (Fig. 1). sandy area (transition zone A), as well as in the The available sediment was collected in live coral-coral rubble (zone B) but absent in the sand area (C) (Fig. 1). Finally, La Entrega situ near the mouth and feces near the anus has been subjected to intense touristic activity of 20 specimens of H. (Stauropora) fuscoci- and recurrent dredging at least yearly since the nerea (Fig. 2A, 2B, 2C), randomly selected in early 1990’s, which has resulted in high quanti- each of the stations A and B, in which coral ties of organic matter, therefore diminishing the sand (A) and coral debris (B) predominate health of the system (López-Pérez & Hernán- (Fig. 1). The samples were collected manu- dez-Ballesteros, 2004; Díaz-Díaz, 2017). ally with a plastic spoon, placed in individual 68 Revista de Biología Tropical, ISSN electrónico: 2215-2075 Vol. 69(S1): 66-79, March 2021 (Published Mar. 30, 2021) Fig. 2. A. Holothuria (Stauropora) fuscocinerea. B. Feces of Holothuria (Stauropora) fuscocinerea. C. Close-up feces. sealable plastic bags, and stored frozen until animals from the water (Uthicke, 1999) at the subsequent processing. end of the experiment, using an Oahus CR2200 Furthermore, individuals of H. (Stauro- balance (± 1 g precision). pora) fuscocinerea were placed in individual enclosures (one individual per enclosure, ten Laboratory work: Samples (sediment enclosures) at station C in order to measure the and feces) were thawed, placed on aluminum rate of excretion of the cucumbers over a total trays and dried at room temperature until dry. period of 24 h. These enclosures were con- Sediment texture analysis was then performed structed of wire rod and cloth mesh and were 1 and the content of organic carbon (O.C.) and m in diameter (Fig. 3); on the upper and lateral organic matter (O.M.) determined.