Early succession of micro‐periphyton communities in kelp bed and barren ground ecological systems

Abstract

In shallow sublittoral rocky habitats of the Southeast Pacific, two conspicuous ecological systems exist; kelp beds dominated by large Laminariales algae, and barren grounds dominated by crustose coralline algae and sea urchins. The aim of this study was to examine the successional development of micro‐periphyton communities in both ecological systems using a colonization experiment conducted in Northern Chile. In both ecological systems, we installed replicated ceramic plates at 10 m depth and samples were taken after 1, 2, 4, 6, 8 and 14 days of exposure. Bacteria, diatoms, protozoans and small eukaryotes were identified, quantified and analysed. The succession of micro‐periphyton communities in both ecological systems followed a common pattern consisting of a net accumulation of functional groups and taxa over time; however, the total density of all groups was significantly higher in the kelp beds. In addition, the community structure of the developing micro‐periphytons was different and specific for each ecological system. Although previous studies have suggested that kelp beds and barren grounds are capable of switching from one state to the other without substantial changes in biodiversity, our results show that each of these ecological systems promotes its own successional development, suggesting that they are unique, self‐organized entities. This study is the first step towards an understanding of these ecological systems operating independently at this scale of organization.

Successional patterns of hard-bottom macrobenthic communities at kelp bed (Lessonia trabeculata) and barren ground sublittoral systems

“…Our findings show that kelp bed and barren ground macrobenthic communities followed different successional pathways, which is similar to the description of the successional development of micro-periphyton communities at these systems (Uribe et al, 2014). This result adds further support to the conclusions draw by Ortiz (2008) suggesting that kelp beds and barren grounds are essentially different systems.…”

“…These processes may promote the recruitment of species (Graham, 2004;Parnell, 2015), that prefer nutrient-rich, less illuminated and cooler waters in the kelp bed. A recent experiment in our study area has also reported differences in environmental factors between kelp beds and barren grounds (e.g., illumination, temperature) (Uribe et al, 2014). However, the kelp canopy may also inhibit the colonisation of understory algae via shading (Reed and Foster, 1984;Connell, 2005) and whiplash effect (Santelices, 1990;Morrow and Carpenter, 2008).…”

“…The topography was similar in both systems. It consisted of boulders and large rocks on an~45°slope (see details in Uribe et al, 2014). In the kelp bed, only L. trabeculata formed the canopy; the understory algae community was composed of small filamentous red algae such as Antithamnionella ternifolia, Griffithsia chilensis and bladed Rhodymeniales, the filamentous green alga Cladophora herpestica and small blades of Ulva sp.…”

Comparing the stability of successional transient models in kelp forests and barrens (south‐east Pacific): Implications for conservation monitoring

“…Early studies have shown not only that community succession in kelp forests and barrens is habitat and community specific (Uribe et al, 2015a; Uribe et al, 2015b) but also that barren beds exhibit a shorter structural discrete‐stage pathway than kelp forests (Uribe & Ortiz submitted). Therefore, the current findings emphasize the relevance of controlling the indiscriminate harvesting of kelp species, since vast coastal areas have become dominated by barrens along the northern Chilean coast (Ortiz & Levins, 2017), modifying the morphology of the remaining plants and reducing the biodiversity (Byrnes et al, 2006; Vega, 2016; Teagle et al, 2017; Miller et al, 2018).…”

“…Consequently, the overexploitation of kelp species could change the natural trajectory of kelp beds, promoting barren grounds in such habitats. Recently, it has been described that both kelp beds and barren grounds show significantly different successional patterns from early stages dominated by micro‐periphyton to advanced assemblages shaped by macrobenthic organisms (Uribe et al, 2015a; Uribe et al, 2015b).…”