Botanica Marina 52 (2009): 655–667  2009 by Walter de Gruyter • Berlin • New York. DOI 10.1515/BOT.2009.076 Article in press - uncorrected proof 2009/12 Review Drivers of colonization and succession in polar benthic macro- and microalgal communities Gabriela Laura Campana 1–3, *, Katharina Zacher 4 , Anna Fricke 4–6 , Markus Molis 7 , Angela Wulff 8 , Marı´a Liliana Quartino 1,9 and Christian Wiencke 4 1 Departamento de Ciencias del Mar, Instituto Anta ´ rtico Argentino, Cerrito 1248 (1010AAZ), Buenos Aires, Argentina, e-mail: gcampana@dna.gov.ar 2 CONICET, Rivadavia 1917 (1033AAJ), Buenos Aires, Argentina 3 Departamento de Ciencias Ba ´ sicas (PIEA), Universidad Nacional de Luja ´ n, Rutas 5 y 7 (6700), Luja ´ n, Buenos Aires, Argentina 4 Department Seaweed Biology, Section Functional Ecology, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany 5 Leibniz Center for Tropical Marine Ecology, Fahrenheitstr. 6, 28359 Bremen, Germany 6 Bremen International Graduate School for Marine Sciences ‘‘Global Change in the Marine Realm’’ (GLOMAR), Bremen International Graduate School for Marine Sciences, Leobener Str., 28359 Bremen, Germany 7 Department of Seaweed Biology, Section of Functional Ecology, Biologische Anstalt Helgoland, Alfred Wegener Institute for Polar and Marine Research, Marine Station, Kurpromenade 201, 27498 Helgoland, Germany 8 Department of Marine Ecology, University of Gothenburg, Box 461, SE-405 30, Go ¨ teborg, Sweden 9 Museo Argentino de Ciencias Naturales ‘‘B. Rivadavia’’, Av. A. Gallardo 470 (C1405DJR), Buenos Aires, Argentina * Corresponding author Abstract Information on succession in marine benthic primary pro- ducers in polar regions is very scarce, particularly with regard to effects of abiotic and biotic drivers of com- munity structure. Primary succession begins with rapid colonizers, such as diatoms and ephemeral macroalgae, whereas slow, highly seasonal recruitment and growth are characteristic of annual or perennial seaweed spe- cies. Colonization of intertidal and subtidal assemblages on polar rocky shores is severely affected by physical disturbance and by seasonal changes in abiotic condi- tions. Biotic factors, such as grazing, can strongly affect colonization patterns and also alter competitive interac- tions among benthic algae. Ambient UV radiation affects the diversity of macroalgal communities during early and later stages of succession. In contrast, microalgal assemblages have high tolerance to UV stress. Climate warming could alter algal latitudinal distribution and favor invasion of polar regions by cold-temperate species. Reduced sea ice cover and retreating glaciers could expand colonization areas but alter light, salinity, sedi- mentation and disturbance processes. Although the key role of macroalgae in coastal systems and, to a much reduced extent, the importance of microphytobenthos have been documented for polar regions, information on the successional process is incomplete and will benefit from further ecological studies. Keywords: Antarctica; Arctic; global change; microphytobenthos; seaweeds. Introduction The ecology of benthic communities in polar regions was little studied until quite recently. Available knowledge has focused on the description of spatial and temporal pat- terns of the geographic distribution and vertical zonation of seaweeds and sessile invertebrates. Profound eco- logical understanding of the underlying processes and drivers was missing. This applies especially to the micro- phytobenthos, which has been barely investigated. Although information on the ecology of polar benthic algal communities is available (Klo ¨ ser et al. 1994, 1996, Quartino et al. 2001, Irving et al. 2005, Konar and Iken 2005, Wulff et al. 2009), it is a remarkable fact that the vast majority of investigations have focused on the macrozoobenthos. For these animal assemblages, the impact of ice scour on community structure and diversity has been the focus of most attention (Gutt 2001, Piepenburg 2005). Finally, most studies on primary pro- ducers have been of an observational nature, correlating patterns of diversity to the potential drivers (Cunningham and McMinn 2004, Quartino et al. 2005, Johnston et al. 2007). Long-term succession studies have allowed char- acterization of hard-bottom macrobenthic assemblages in the Arctic (Beuchel and Gulliksen 2008 and references therein) and in Antarctica (Bowden et al. 2006, Barnes and Conlan 2007). These studies show that the succes- sion of nearshore communities is either slow and contin- ual or pulsed with inter-annual mass events of coloni- zation (Barnes and Conlan 2007). The colonization process of hard-bottom polar benthic communities has been studied by clearing natural sub- strata and placement of settlement panels, followed by direct observation, analyses of underwater photographs or transference of colonized substrata to the laboratory Brought to you by | University of Arizona Library Authenticated | 150.135.135.70 Download Date | 12/23/12 5:23 PM