View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CONICET Digital Journal of the Marine Biological Association of the United Kingdom, 2013, 93(8), 2049–2058. # Marine Biological Association of the United Kingdom, 2013 doi:10.1017/S0025315413001069 Benthic diversity and assemblage structure of a north Patagonian rocky shore: a monitoring legacy of the NaGISA project m.e. rechimont1, d.e. galva’ n2, m.c. sueiro3, g. casas4, m.l. piriz4, m.e. diez5, m. primost1, m.s. zabala1,f.ma’ rquez6, m. brogger7, j.e.f. alfaya1 and g. bigatti1 1Laboratorio de Reproduccio´n y Biologı´a Integrativa de Invertebrados Marinos (LARBIM), CENPAT–CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 2Laboratorio de Ecologı´a y Manejo de Peces de Arrecife, CENPAT–CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 3Grupo de Ecologı´a en Ambientes Costeros, CENPAT– CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 4Laboratorio de Algas Marinas, Grupo de Ecologı´aen Ambientes Costeros (GEAC), CENPAT–CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 5Laboratorio de Parasitologı´a, CENPAT–CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 6Biologı´a evolutiva de moluscos marinos, CENPAT–CONICET, Bvd Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina, 7Laboratorio de Ecosistemas Costeros, MACN–CONICET, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Avenida A´ ngel Gallardo 470, C1405DJR, Buenos Aires, Argentina The rocky shore of Punta Este, Golfo Nuevo (Patagonia, Argentina), was sampled by means of the standardized NaGISA (CoML) protocol, that was aimed to generate biodiversity baseline data in six levels, from high intertidal to 10 m depth. Based on the generated data, we analysed the benthic assemblage structure, species richness, mean abundance and the dis- tribution pattern of invertebrate functional groups, typifying species in each intertidal and subtidal level. The intertidal sampled is exposed to extreme physical conditions higher than any other rocky shore system studied, with air temperature variation of 408C during the year, maximum winds of 90 km/h and semidiurnal tides of 5 m amplitude; on the other hand subtidal presents less thermal variation (DT108C throughout the year) and more homogeneous physical conditions. We identified 64 taxa represented by six animal phyla: Mollusca, Arthropoda, Annelida (Polychaeta), Echinodermata, Cnidaria and Nemertea; and three algal phyla: Chlorophyta, Rhodophyta and Heterokontophyta (class: Phaeophyceae). Ordination non-metric multidimensional scaling plots showed three different assemblages in terms of species composition (intertidal, subtidal 1 m level and subtidal 5–10 m levels). The intertidal was represented by suspension feeders, mainly Mollusca. The tiny mussels Brachidontes rodriguezii and Brachidontes purpuratus, and the algae Corallina officinalis domi- nated the intertidal and promote positive interaction (amelioration), preventing other species from the extreme physical stress. The subtidal was mainly represented by grazers. Our results showed a tendency of suspension feeders to decrease and grazers and predators to increase from high intertidal to subtidal, probably driven by decreasing physical stress. The gastropod Tegula patagonica, the sea urchins Arbacia dufresnii and Pseudechinus magellanicus and the invasive algae Undaria pinnatifida were the most abundant species in 1 m–10 m levels. Based on previous work performed in the region, we hypothesize that the differences registered between intertidal and subtidal levels could be explained in part by an increase in physical stress at the intertidal, with low predation pressure that promotes positive interactions, while in the subtidal the increase in con- sumers and decrease of physical stress could lead to associational defences. Our results could be useful as baseline data to develop a sustainable network for long-term monitoring of benthic community changes due to anthropogenic activities. Keywords: biodiversity, rocky shores, Patagonia, physical stress, Census of Marine Life Submitted 22 March 2013; accepted 1 July 2013; first published online 13 August 2013 INTRODUCTION evidence that climate is changing and this change is driving important alterations in the composition and structure of a Making inventories and monitoring biodiversity are crucial to very diverse array of natural assemblages: terrestrial, marine identifying the natural processes and the human activities that and aquatic (Cruz-Mota et al., 2010). Destruction of natural affect ecosystems. The loss of biodiversity should be of con- habitats, loss of strong interacting species (such as habitat siderable concern to everyone because it threatens the func- formers and keystone species), introduction of non-native tioning of a system (Rigby et al., 2007). There is compelling species (Orensanz et al., 2002), over-exploitation of natural resources, such as overfishing (Jackson et al., 2001), urban pol- lution (Dı´az et al., 2002) and climate change (Smith et al., Corresponding author: 2006) are all potential threats to biodiversity. The first step G. Bigatti towards understanding these complexities, on the large Email: [email protected] scale, is to investigate global patterns of biodiversity (i.e. 2049 Downloaded from https:/www.cambridge.org/core. Open University Library, on 05 Feb 2017 at 08:36:59, subject to the Cambridge Core terms of use, available at https:/www.cambridge.org/core/terms. https://doi.org/10.1017/S0025315413001069 2050 m.e. rechimont et al. taxonomic composition and diversity of assemblages) over a 2006; Kelaher et al., 2007; Torres & Caille, 2009; Irigoyen broad range of spatial scales, and to develop a sustainable et al., 2010; Miloslavich et al., 2011; Silliman et al., 2011; network for long-term monitoring (Rigby et al., 2000). To Sueiro et al., 2011). In this context, the rocky shore of Punta detect changes in natural communities, and unequivocally Este (Golfo Nuevo, Patagonia) was selected as one of the relate them to anthropogenic impacts or climate disruptions, sites distributed along the world for the Census of Marine proper baseline data are of utmost importance (Cruz-Mota Life (CoML), an international science programme for inven- et al., 2010), as well as to have knowledge about the processes torying and monitoring marine biodiversity all over the governing the patterns observed locally in rocky intertidal habi- world (finished in 2010). The main goal of this project was tats (Underwood, 2000). In this sense, it is important to perform to establish an initial census for future comparisons and moni- experiments to test hypotheses about the processes that structure toring programmes over time (Iken & Konar, 2003). Through and maintain diversity in such communities. Alternatively, stan- the combination of a simple, cost-efficient and intentionally dardized global monitoring programmes can be put in place to low-tech sampling protocol and a hierarchically nested assess changes in biodiversity and relate those changes to poss- design, the project NaGISA (Natural Geography in Shore ible anthropogenic causes (Darling & Coˆte´, 2008). Areas), carried out a series of globally-distributed standard In the particular case of coastal ecosystems, studies on transects in more than 250 sites within 28 countries. At benthic community structure are an adequate tool to assess present, the NaGISA database, growing since 2003, is available the impact caused by pollution (Dı´az et al., 2002), mainly through the Ocean Biogeographic Information System (OBIS) due to the reduced mobility of benthic species, which and contains nearly 54,666 records for 2867 taxa (Plos collec- cannot avoid the potentially dangerous environmental con- tions, 2011). Based on the data generated by the NaGISA ditions. For instance, on the southern Atlantic shores, the project, the aim of the present study was directed to describe structure of the intertidal community characterized by the the benthic assemblages in terms of richness, specific and tiny mussel Brachidontes rodriguezii, has been successfully functional composition at different levels (intertidal and sub- used to detect environmental impact due to domestic tidal) of Punta Este rocky shore, as baseline data that could be sewage (Lo´pez Gappa et al., 1990, 1993; Vallarino, 2002; useful for future temporal monitoring programmes, allowing Vallarino et al., 2002). Therefore, baseline information on to detect changes in biodiversity or ecosystem function due benthic community structure is critical to avoid confounding to anthropogenic impacts or environmental changes. the consequences of an impact, given the high level of varia- bility in natural assemblages (Smith & Simpson, 1995; Gelin et al., 2003). Several authors have pointed out that pre-impact MATERIALS AND METHODS data are essential to understand effects of pollution such as an oil spill (Paine et al., 1996). The problem is that the databases Study area available at the moment are restricted to a few regions and locations throughout the world (Cruz-Motta et al., 2010). The rocky shore of Punta Este (42847′5.7′′S64857′7.3′′W) is Despite the ecological and economic importance of ~8 km from the city of Puerto Madryn, located in northeast Patagonian coasts, its benthic biodiversity remains poorly Patagonia, Argentina and on the west coast of Golfo Nuevo understood, except for some records in the literature (Figure 1). The region is characterized