Original Article / Artigo Original Bertrán et al.: Variation in Budi LagoonBJOCE macrobenthos Macrobenthos of the coastal Budi Lagoon, southern Chile: Changes associated with seasonal environmental variation Carlos Bertrán1, Pablo Fierro1, Elizabeth Encalada1, Fernando Peña-Cortés2, Jaime Tapia3, Enrique Hauenstein4, Luis Vargas-Chacoff1,5* 1 Institute of Marine Science and Limnology, Universidad Austral de Chile, Chile. 2 Territorial Planning Laboratory, Universidad Católica de Temuco, Chile 3 Institute of Chemistry and Natural Resources, Universidad de Talca, Chile 4 Faculty of Sciences, Universidad Católica de Temuco, Temuco, Chile. 5 Centro Fondap de Investigación de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile. *Corresponding author: [email protected] Financial Support: This study was possible due to the support of FONDECYT projects 1110798 and 1151375. ABSTRACT RESUMO The purpose of the present study was to investigate O objetivo do presente estudo foi investigar the seasonal relationship of macrobenthos richness a relação sazonal entre macrobentos e and abundance with sediment characteristics características do sedimento, tais como textura (i.e. texture and organic material) for the coastal e material orgânico, na lagoa costeira Budi Budi Lagoon in southern Chile. Physicochemical Lagoon, sul do Chile. Medidas físico-químicas measurements and macrobenthos samples were e amostragem do macrobentos foram realizadas taken over the course of a year at nine sampling durante um ano em nove localidades. Sedimento stations. Sandy-muddy sediment was the most arenoso-lodoso foi o mais comum na lagoa, common, and high percentages of organic material e percentagens elevadas de material orgânico were registered, varying significantly between foram registradas, variando significativamente seasons and stations. The recorded organic material entre as estações e locais de coleta. Em relação was related to natural (resident wild birds) and a fauna, foram identificados 28 taxas bentônicos anthropogenic (agriculture) sources. Regarding e 7092 indivíduos, que apresentaram variação fauna, 28 benthonic taxa and 7092 individuals were temporal e espacial. As espécies mais abundantes identified, with temporal and spatial variations. The durante todo o ano foram os moluscos Littoridina most abundant taxa year-round were the molluscs cumingii e Kingiella chilenica, e o poliqueta Littoridina cumingii and Kingiella chilenica and Prionospio patagonica. Os resultados obtidos the bristle worm Prionospio patagonica. Together, evidenciaram o importante impacto da matéria the obtained results evidence the important impact orgânica sobre o macrobentos, com riqueza e of organic material on the macrobenthos, with abundância da fauna diminuindo em presença de macrobenthic richness and abundance decreasing alto teor de matéria. As variações encontradas in conditions of high organic material content. The para os diferentes taxons indicaram resposta da recorded variations for different taxa may indicate fauna ao uso da terra ao redor de Budi Lagoon, a response to the land use around the Budi Lagoon, que intensamente utilizada para agricultura e which is intensely subjected to agricultural and atividades turísticas. tourist activities. Descriptors: Macrobenthos, Budi Lagoon, Araucania, Descritores: Macrobentos, Budi Lagoon, Araucanía, Sediments, Spatial variability. Sedimentos, Variabilidade espacial. http://dx.doi.org/10.1590/S1679-87592016113306403 BRAZILIAN JOURNAL OF OCEANOGRAPHY, 64(3):239-248;2016 239 Bertrán et al.: Variation in Budi Lagoon macrobenthos INTRODUCTION MATERIAL AND METHODS Most animal populations show considerable spatial Study site and temporal fluctuations in distribution and abundance The Budi Lagoon (38º49’30” S, 73º23’30” W) begins (UNDERWOOD; CHAPMAN, 1996; BENEDETTI- about one mile south of the Imperial River estuary in CECCHI et al., 2001; BERTRÁN et al., 2001; FIERRO southern Chile. The Budi Lagoon sporadically connects et al., 2014; FIERRO et al., 2015). In the case of with the Pacific Ocean, specifically from the end of benthic macrofauna, distribution and abundance are autumn until the beginning of spring. This lagoon has a mainly related to certain variables of the sediment- surface area of 57.4 km2, and its basin has a dry coastal water interface, where multiple effects of contamination landscape that is highly fragmented by anthropogenic and organic enrichment are exerted (GLÉMAREC, activities, with native oak-laurel-lingue and temo-pitra 1986). The principal physicochemical variables that forests (BERTRÁN et al., 2006; 2010). determine macrobenthic distribution are temperature, salinity, suspended solids, nitrates (HOLLAND et al., Sampling and analytical method 1987; BEUKEMA, 1990; FIERRO et al., 2015), and Sampling was performed in 2005 during each sediment characteristics, such as texture and organic of the four seasons at nine sampling stations: Budi material content (RITCHER, 1985; NICHOLS et al., River (E1), Temo (E2), Deume 1 (E3), Deume 2 1986). Macrobenthic organisms inhabit different types of (E4), Deume 3 (E5), Comue (E6), Bolleco (E7), sediments (HYNES, 1970) over the course of the year Allipen (E8), and Botapulli (E9) (Figure 1). At each (BERTRÁN, 1989; BERTRÁN et al., 2001; FIERRO et station, water was sampled using a Ruhtner bottle, al., 2012), generating varied distribution and abundance and the temperature and salinity of the bottom layer patterns (JARAMILLO et al., 2001). was measured. Sediment samples (5 replicates per The distribution of the macrobenthos has possible station) were also collected using an Emery Dredge application in estimating the spatial and temporal (0.25 m2) to sample the macrobenthos, characterize variations of different ecosystems, such as coastal sediment texture (FOLK, 1980), and determine lakes and estuaries. Lagoons are a non-continental, organic material (BYERS et al., 1978). Macrobenthos transitional ecosystem temporally influenced by samples were sieved through a 0.5 mm mesh, fixed in seawater (KJERFVE, 1994; PÉREZ-RUZAFA et al., 10% formalin, transported to the Bentos Laboratory 2011). The entrance of high-salinity water into lagoons of the Universidad Austral de Chile, and preserved sufficiently sustains fauna with estuarine traits (DÍAZ- in 70% ethanol. In the laboratory, samples were JARAMILLO et al., 2008). Additionally, lagoons and examined under a stereoscopic microscope, and taxa estuaries both present high environmental variability, were identified to the lowest possible taxonomic level leading some authors to consider both as a single using specialized literature. ecosystem unit (STUARDO; VALDOVINOS, 1989; BERTRÁN et al., 2010). One such ecosystem unit is the Budi Lagoon, where the periodic entrance of seawater largely and seasonally modifies water parameters (BERTRÁN et al., 2010). Furthermore, the permanent presence of aquatic birds and anthropic activity in the watershed, particularly near the shoreline, means that this lagoon is constantly incorporating organic material (PEÑA- CORTÉS et al., 2006a; 2006b, 2011). The objective of this study was to explore the relationship between seasonal variations in benthic macrofauna communities and fluctuations in water characteristics of the coastal Budi Lagoon, including sediment texture and organic Figure 1. Location of the Budi Lagoon and sampling stations (black circle). Arrow indicates connection between the lagoon and sea. material content. 240 BRAZILIAN JOURNAL OF OCEANOGRAPHY, 64(3):239-248;2016 Bertrán et al.: Variation in Budi Lagoon macrobenthos Statistical analysis To examine the patterns in organic material, non- The community structure of the Budi Lagoon metric multidimensional scaling and cluster analyses were macrobenthos was described for each site and season based performed (Figure 2). During the summer, stations E9 on the following indexes: Number of taxa, Abundance, and and E1 were the most different from the other sampling Shannon-Wiener diversity (H’), following BROWER et stations; while in the autumn, stations E9 and E8 were the al. (1990). Community structure and organic material were most different. In the winter, stations E7, E8, and E4 were analysed using non-metric multidimensional scaling analysis the most different, but in spring, station E9 was once again as the ordination method, and similitude between sampling the most different from all other stations. stations was based on a similarity matrix constructed using the Bray-Curtis similarity index. This analysis was performed in Description of the macrobenthos community PRIMER v.6 (Plymouth Routines in Multivariate Ecological During the sampling period, a total of 28 taxa were Research) (CLARKE et al., 2005). recorded: Polychaeta (4), Gastropoda (3), Oligochaeta For the variables that fulfilled assumptions of (1), Bivalvia (3), Amphipoda (1), Isopoda (2), Ostracoda normality, independence, and homoscedasticity, a two-way (1), Nematoda (1), Nemertinea (1), Platyhelminthes (1) ANOVA was performed. In all cases, the two factors were and Insecta (10) (Table 2). A total of 7092 individuals space (sampling stations) and time (season). Sediment were sampled, of which, the most frequent taxon was the values were first arcsine transformed. Since abundances Mollusca phylum (47.14%, 3343 individuals), followed were non-parametric, this variable was assessed using the by Annelida (40.65%, 2883 individuals). Together, these Kruskal-Wallis test. Significant differences (p<0.05) were taxons constituted more than 80% of the macrobenthos