Marine Environmental Research 149 (2019) 67–79

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Marine Environmental Research

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Long-term persistence of the floating bull antarctica from the T South-East Pacific: Potential contribution to local and transoceanic connectivity ∗ Fadia Talaa,b, , Boris A. Lópezc, Marcel Velásquezd,h, Ricardo Jeldrese,f, Erasmo C. Macayae,f,g, Andrés Mansillad,h, Jaime Ojedad,h,j, Martin Thiela,g,i a Departamento de Biología Marina, Universidad Católica del Norte, Larrondo, 1281, Coquimbo, b Centro de Investigación y Desarrollo Tecnológico en Algas (CIDTA), Facultad de Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile c Departamento de Acuicultura y Recursos Agroalimentarios, Universidad de Los Lagos, Avenida Fuchslocher, 1305, Osorno, Chile d Laboratorio de Macroalgas Antárticas y Subantárticas (LMAS), Universidad de Magallanes, Facultad de Ciencias, Casilla 113-D, Punta Arenas, Chile e Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile f Centro FONDAP de Investigaciones en Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Chile g Millennium Nucleus and Sustainable Management of Oceanic Island (ESMOI), Coquimbo, Chile h Instituto de Ecología y Biodiversidad, IEB-Chile, Universidad de Chile, Santiago, Chile i Centro de Estudios Avanzados en Zonas Áridas, Coquimbo, Chile j School of Environmental Studies, University of Victoria, Victoria, British Columbia, Canada

ARTICLE INFO ABSTRACT

Keywords: Current knowledge about the performance of floating as dispersal vectors comes mostly from mid Chile latitudes (30°–40°), but phylogeographic studies suggest that long-distance dispersal (LDD) is more common at high latitudes (50°–60°). To test this hypothesis, long-term field experiments with floating southern bull kelp Floating persistence Durvillaea antarctica were conducted along a latitudinal gradient (30°S, 37°S and 54°S) in austral winter and Rafting summer. Floating time exceeded 200d in winter at the high latitudes but in summer it dropped to 90d, being still Dispersal higher than at low latitudes (< 45d). Biomass variations were due to loss of buoyant fronds. Reproductive Floating seaweeds Temperature activity diminished during long floating times. Physiological changes included mainly a reduction inphoto- synthetic (Fv/Fm and pigments) rather than in defence variables (phlorotannins and antioxidant activity). The observed long floating persistence and long-term acclimation responses at 54°S support the hypothesis ofLDDby kelp rafts at high latitudes.

1. Introduction Batista et al., 2018). Floating seaweeds are recognized as important natural rafting substrata for diverse organisms, providing food, habitat The connectivity between populations is an essential aspect for and refuge during the travel (Rothäusler et al., 2012; Gutow et al., understanding population dynamics, dispersal and migration, gene 2009, 2015; Macaya et al., 2016; López et al., 2018). However, current flow, colonization of a new or altered habitat, and range expansion knowledge about floating persistence, physiological acclima- (Kool et al., 2013). In marine environments rafting on biotic and abiotic tion and reproductive capacities comes mainly from low and mid lati- substrata is recognized as an important dispersal mechanism to connect tudes and mostly from mesocosm experiments (e.g. Hobday, 2000; close or distant populations. The significance of rafting as a transport McKenzie and Bellgrove, 2008; Vandendriessche et al., 2007; mechanism is most relevant in species with limited autonomous dis- Rothäusler et al., 2009, 2011a, 2011b; Graiff et al., 2016), even though persal capacities (i.e. absence of larvae or low mobility of propagules), phylogeographic studies have identified important transoceanic rafting with rafting allowing them to extend their distribution ranges according routes at high latitudes (Fraser et al., 2010, 2018; Coyer et al., 2011; to their physiological/reproductive tolerances, ecological interactions Rothäusler et al., 2012; Moon et al., 2017). and environmental factors (Thiel and Gutow, 2005a; 2005b; Coyer The region is characterized by vast expanses of open et al., 2011; Fraser et al., 2011; Nikula et al., 2013; Waters et al., 2013; ocean, with a few dispersed islands, the southern tip of

∗ Corresponding author. Departamento de Biología Marina, Universidad Católica del Norte, Larrondo, 1281, Coquimbo, Chile. E-mail address: [email protected] (F. Tala). https://doi.org/10.1016/j.marenvres.2019.05.013 Received 13 March 2019; Received in revised form 16 May 2019; Accepted 18 May 2019 Available online 24 May 2019 0141-1136/ © 2019 Elsevier Ltd. All rights reserved. F. Tala, et al. Marine Environmental Research 149 (2019) 67–79 and , all connected by the Antarctic Circumpolar Current antarctica throughout its range of geographical distribution. However, (ACC or West Wind Drift) (Moon et al., 2017). The environmental high plasticity in chemical, physiological, reproductive and morpholo- conditions (i.e. lower temperature and solar radiation), fast local and gical responses has been described in D. antarctica facing environmental oceanic currents and winds can promote long-distance dispersal (LDD) conditions in different local zones and under laboratory conditions (e.g. and connectivity throughout this zone (Fraser et al., 2011, 2018; Santelices et al., 1980; Hay, 1994; Collantes et al., 2002; Smith et al., Gillespie et al., 2012; Hawes et al., 2017; Waters and Craw, 2018). 2010; Cruces et al., 2012, 2013; Tala et al., 2016, 2017; Mansilla et al., Population connectivity between distant islands or landmasses in the 2017; Méndez et al., 2019). Short-term laboratory experiments have subantarctic region has been confirmed by molecular studies of floating shown that an increase in 5 °C has a significant impact on physiological seaweeds such as pyrifera (L.) C. Agardh (Macaya and variables in the at 30°S, 36°S and 53°S latitudes and that photo- Zuccarello, 2010) and Durvillaea antarctica (Chamisso) Hariot (Fraser synthetic acclimation was possible mainly in winter (unpublished data). et al., 2009, 2010, 2018), as well as the associated species Herpodiscus The SE Pacific temperate Chilean coast offers an excellent natural durvillaeae (Lindauer) G. R. South (Fraser and Waters, 2013; Fraser laboratory, characterized by a latitudinal gradient of sea surface tem- et al., 2013), braseltonii Murúa, Goecke and Neuhauser (Blake perature (Ramos-Rodríguez et al., 2012; Tapia et al., 2014) and solar et al., 2017), epifaunal and molluscs (Nikula et al., 2010, radiation (Vernet et al., 2009). This spatial pattern in combination with 2013), direct-developing species as Siphonaria fuegiensis Güller, Zalaya seasonal changes in these variables (Huovinen et al., 2006; Rothäusler and Ituarte (González-Wevar et al., 2018) and non-buoyant seaweeds as et al., 2009; Tala et al., 2016) produces an environmental variability Adenocystis utricularis (Bory) Skottsberg (Fraser et al., 2013), Capreolia that floating kelps must cope with during their rafting journeys. A implexa Guiry and Womersley (Boo et al., 2014) and Agarophyton longer floating time should be accompanied by an adequate physiolo- (Gracilaria) chilensis (C. J. Bird, McLachlan et E. C. Oliveira) Gurgel, J. gical adjustment that allows maintaining biomass production and re- N. Norris et Fredericq (Guillemin et al., 2014). In combination, these productive capacity when arriving in a new habitat. Therefore, D. reports hint at the important role of rafting at high latitudes as a dis- antarctica (considering its positive buoyancy and wide geographic dis- persal and connectivity mechanism among marine populations (Fraser tribution throughout the subantarctic region) can be used as an ideal et al., 2011, 2013; Cumming et al., 2014; reviewed in Moon et al., biological model to evaluate the performance of floating kelps under 2017). divergent conditions along an extensive latitudinal gradient. Depending on season and the geographic origin, floating seaweeds Herein we tested the following hypotheses: (i) floating D. antarctica can cope with changing abiotic (Hobday, 2000; Rothäusler et al., better adjust to sea surface conditions and therefore float for longer 2011a; Graiff et al., 2013; van Hess et al., 2019) and biotic conditions time periods at high than at mid-low latitudes, and (ii) winter en- (Vandendriessche et al., 2007; Rothäusler et al., 2009, 2011a; Gutow vironmental conditions are more beneficial to allow floating persistence et al., 2012; Graiff et al., 2016) that influence their physiological per- than summer conditions. In order to test these hypotheses, in situ long- formance, tissue integrity, reproductive capacities, and ultimately the term experiments were conducted during contrasting seasons (winter persistence at the sea surface. High temperature and solar radiation vs. summer) at three sites along the SE Pacific coast (30°S - 54°S) to occurring at low latitudes and/or during summer accelerate tissue de- determine changes in morphological (biomass change), physiological gradation and affect the photosynthetic efficiency and metabolite (chlorophyll a fluorescents in PSII, pigments, phlorotannin contents, concentrations, contributing to rapid sinking of floating kelps and antioxidant activity), and reproductive traits of floating bull kelp D. (Rothäusler et al., 2009, 2011b; Graiff et al., 2013, 2016; Tala et al., antarctica. These results will allow to understand the underlying me- 2013, 2016). However, under more favourable environmental condi- chanisms that facilitate the long persistence capacity of floating sea- tions of solar radiation and temperature, floating seaweeds are able to weed at high latitudes as suggested by phylogeographic studies. continue growing and even reproducing for extended time periods after detachment (Macaya et al., 2005; Hernández-Carmona et al., 2006; 2. Materials and methods McKenzie and Bellgrove, 2008; Rothäusler et al., 2009; Graiff et al., 2013, 2016; Tala et al., 2013, 2016). Therefore, at higher latitudes and 2.1. Experimental zones under more benign environmental conditions (i.e. autumn-winter) floating seaweeds are expected to persist at the sea surface forlonger Long-term field experiments were used to evaluate the spatial (la- than at mid or low latitudes. The relationship between spatial/temporal titude) and temporal (season) effects on floating capacity and perfor- environmental conditions and growth/physiological performance of mance of D. antarctica. The in situ experiments were started during floating seaweeds could enhance the rafting potential and connect austral winter 2014 (July) and late spring-summer 2014/2015 distant populations of both floating seaweeds and their epibiota. (December) at each locality. These experimental sets were henceforth The buoyant bull kelp Durvillaea antarctica (, Phaeophyceae) named as winter and summer experiment, respectively. The experi- is an ecologically important habitat-forming species in cold-temperate mental zones were at low (Coquimbo, Herradura Bay: 29°57′S, intertidal in the southern hemisphere, including the coasts 71°20′W), mid (Concepción, Dichato: 36°29′S, 72°54′W), and high la- of Chile, New Zealand, the Falkland Islands and most subantarctic is- titudes (Punta Arenas, Puerto del Hambre: 53°36′S, 70°55′W) (Fig. 1). lands (Hay, 1994; Fraser et al., 2009). Along the Chilean coast, benthic These study sites (spanning a distance of more than 2,500 km) allowed populations of D. antarctica extend up to 30°S (the northern distribution examination of the spatial gradient in environmental conditions to limit) and south to 56°S in the Diego Ramírez Archipelago (Schlatter which floating rafts are exposed along the SE Pacific coast, including and Riveros, 1987; Ramírez and Santelices, 1991; Fraser et al., 2010; extremes of low and high latitudes according to the distributional range Mansilla et al., 2017) including different biogeographic zones on the of D. antarctica in Chile (López et al., 2018). Each experimental zone South-East (SE) Pacific coast. Two separate clades of D. antarctica have coincides with a different biogeographic region and districts based on been recognized in Chile with different genetic structures (Fraser et al., Camus (2001) and López et al. (2018) (Septentrional District, from 30°S 2009, 2010). The continental clade in southern-central Chile (30°S- to 33°S; Mediterranean District, from 33°S to 37°S; and Magellanic 43°S) features a genetic heterogeneous structure indicating low con- Province, starting from ∼46°S southward). nectivity capacities between adjacent populations. On the other hand, a homogenous southern clade at > 44°S in the Patagonian fjord region 2.2. Sampling of benthic bull kelps for floating experiments has one single and widespread haplotype common to most subantarctic islands and New Zealand (termed the Patagonia/subantarctic clade), At each experimental site, individuals for the experiments were which is highly indicative of LDD at high latitudes (Fraser et al., 2010). selected from the same benthic populations in both seasons. Entire There are no studies integrating biological and genetic aspects in D. thalli (n = 26–32 for season) of D. antarctica were detached with their

68 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

Fig. 1. Map showing the three study zones and sites. Experimental sites (A) and benthic populations (B) of Durvillaea antarctica are shown for Coquimbo (low latitude zone), Concepción (mid latitude zone) and Pta. Arenas (high latitude zone).

holdfasts during low tide from benthic populations near the three ex- zones along the South-East Pacific (SEP) coast (Camus, 2001; Thiel perimental sites: Coquimbo (Puerto Oscuro: 31°25′S, 71°36′W), et al., 2007; Försterra, 2009), where important variations in environ- Concepción (Burca: 36°28′S, 72°54′W), and Punta Arenas (San Isidro mental conditions (such as e.g. temperature, solar radiation, and Lighthouse: 53°47′S, 70°58′W) (Fig. 1). After collection, the experi- freshwater runoff) prevail, which cause important changes in species mental thalli were kept in a cooler at ambient temperature and im- composition and genetic structure of seaweed clades with similar mediately transferred to running seawater tanks in the laboratories morphologies (reviewed in Guillemin et al., 2016). Similar differences where they were prepared for the experiments during the following between these biogeographic regions have been reported for many day. Before the experiments, all individuals were thoroughly rinsed to marine invertebrate taxa (e.g. Véliz et al., 2003; Varela and Haye, 2012; remove epiphytes and fauna. Haye et al., 2014; Trovant et al., 2015). Thus, artificial transport of D. The thallus size of the collected individuals depended on the size antarctica and their epibionts across these biogeographic boundaries structure of each sampled population, the weather conditions and the could potentially produce displacement of non-indigenous species accessibility of each benthic population. Although the sizes of experi- generating undesired impacts on the local communities. Furthermore, mental thalli varied with latitude (sites) and season (Table S1), all logistic challenges in transporting large thalli could potentially affect collected individuals were adults with fully developed floating medulla. their tissue and physiological integrity. For all these reasons no kelps The individuals of D. antarctica differed significantly in total weight were transplanted between sites. However, the responses of benthic and

(F2,118 = 7.433, P < 0.05) and maximum length (F2,179 = 13.162, floating D. antarctica to different environmental conditions in winter vs. P < 0.05) only among sites (Table S2). Significantly (P < 0.05) higher summer can be used to better interpret their acclimation and floating weights were found for thalli from Coquimbo compared to Concepción persistence within each biogeographic zone. and Pta. Arenas (Tables S1 and S2). All sites differed in thallus length, The same experimental set-up was used at the three experimental decreasing in size from Coquimbo to Pta. Arenas (Tables S1 and S2). sites to test whether the independent variables latitude and season and Despite these differences, the size distributions showed extensive their interaction cause variation in morphological/physiological per- overlap among sampling sites and seasons, leading us to conclude that formance of floating bull kelps and thus compromise their floating time. size/age had a negligible effect on the evaluated responses. The experimental bull kelps were tethered (n = 18 to 29; see details in Tables S1b) to a long-line system with buoys (with 1–3 m distance) at 2.3. Experimental design of the long-term floating experiment the sea surface. Each bull kelp was identified with a tag on its main stipe and tied with a plastic cord to the long-line, allowing them to The experimental design did not consider reciprocal transplants freely float at the surface, similar as described in Graiff et al. (2013) and because the experimental sites were situated in different biogeographic Tala et al. (2016). Each tethered thallus was checked weekly to

69 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79 determine its day of sinking, and was considered as sunken when it was respective days of sinking. The size change expressed as % per day was completely submerged. The time of sinking (expressed in days) was calculated from the equation [((FS–IS) ⁄ IS)/T] x 100, where FS and IS indicative of the floating persistence. Sunken thalli were removed from are the final (sinking time) and initial (day 0) size, respectively, inwet the long-line system and transported to the lab in order to take tissue weight (BC) or maximum length (LC) of the experimental thallus at the samples and measurements (see details in point 2.5). respective sinking day (T). The size (total wet weight and maximum length) of each experi- 2.4. Environmental conditions during the study mental floating thallus was also measured every two weeks tode- termine the growth or tissue loss during the floating time. For this, each ® Seawater temperature was monitored every 5 min using a HOBO thallus was carefully removed from the experimental line and measured Pendant Temperature-Light Datalogger (Onset Computer Corporation, after which they were returned to their original position on the line. Bourne, MA, USA) throughout the experimental period at each ex- Biomass or length change (% d−1) was determined as was described perimental site. The dataloggers were attached 0.5 m below the sea above. surface in a horizontal position on each experimental line. Using all A destructive sampling was carried out to determine the within- records from one day, the average daily water temperature was calcu- individual biomass distribution of D. antarctica for the initial benthic lated for each day until the last experimental thallus remained floating. thalli (day 0; n = 8) and for the sunken thalli. The thalli were dissected Monthly averages of photosynthetically active radiation (PAR: μmol into holdfast, stipes and frond, and the wet weight (g) of each portion photons m−2 s−1) for each experimental zone and during the experi- was determined. Tissue weight for each portion was standardized with ment were obtained by satellite data from MODIS Aqua level 3, which respect to the average value obtained from the initial benthic thalli for are freely available from the NASA website (https://oceancolor.gsf. each portion (day 0) and the floating time of each one, thus expressed nasa.gov/cgi/I3). as relative change in biomass (% d−1) for each tissue type. Additionally, the concentrations of seawater nutrients (mg L−1) The percentage of mature individuals was calculated considering were determined at the beginning of each experiment. Seawater sam- the development stage of the conceptacles of each individual thallus for ples (n = 5) were collected at each site to measure concentrations of benthic (initial status) and sunken samples. Thin sections of the blade − − + nitrate (NO3 ), nitrite (NO2 ), ammonium (NH4 ), and phosphate tissue were made and the maturity stages of a total of 30 conceptacles − (PO4 ) by spectrophotometric methods as described in Strickland and were examined for each individual (following the description in Lizée- Parsons (1972). Samples were taken in 500 mL plastic flasks, fixed with Prynne et al., 2016). The mature stage was determined based on the approximately 3 drops of chloroform, and then frozen until analysis. conceptacle characteristics as fully developed gametes, sex differ- entiation and open ostioles. In this stage it is assumed that mature thalli 2.5. Sampling of benthic and floating bull kelps are reproductively competent contributing with viable gametes to dis- perse and settle in a new habitat after rafting journeys. The results were Morphological, reproductive and physiological performance of in- expressed as percentage of mature individuals with respect to the total itial (benthic status) and sunken bull kelps were measured using the individuals evaluated. same protocol as in previous studies with Macrocystis pyrifera (Rothäusler et al., 2009, 2018, 2011b; Graiff et al., 2016) and Durvillaea 2.6.2. Physiological performance antarctica (Graiff et al., 2013; Tala et al., 2013, 2016). The initial per- In order to evaluate the changes in the physiological variables formance status was determined for eight of the benthic thalli at the during floating time, chlorophyll a fluorescence of PSII, concentration moment of collection (day 0). The thalli were chosen randomly to re- of chlorophyll a and soluble phlorotannins, and antioxidant activity present the experimental “population” from each site and season. The were determined for the benthic (n = 8) and the experimental bull tethered individuals were then sampled at their sinking day to de- kelps when they had sunken from the sea surface. All physiological termine their performance changes using the same procedures at the procedures were done in similar ways as in previous studies with D. three experimental sites (see details below). When a sunken thallus was antarctica (Graiff et al., ;2013 Tala et al., 2013, 2016; Lizée-Prynne detected, it was removed from the long-line systems and transported in et al., 2016, 2017) and are briefly described below. a cooler to the respective nearby laboratory for further processing. The maximal quantum yield (Fv/Fm) was considered as an indicator Tissue samples for the physiological variables (see details below) from of photosynthetic activity and overall viability of the thallus, which is benthic and sunken thalli were taken from the middle of the largest affected by stress conditions during floating time. To determine the blade with a cork borer and gently cleaned from epibionts with soft maximal quantum yield of fluorescence (Fv/Fm), three small blade paper towels and seawater as described in Tala et al. (2016). The tissue sections (∼3 cm) from each thallus were cut off and incubated for samples were obtained from photosynthetically active portions in order 20 min in the dark and measured six times (two times each sections). to evaluate the physiological changes at the time of sinking. Con- Mean values of the six measurements represented the average response sidering the large size of experimental thalli, a small piece of photo- for each experimental thallus. The Fv/Fm was measured in vivo using a synthetically active tissue was suitable to determine physiological re- computer-aided portable pulse amplitude modulated fluorometer. sponses to environmental change as had been shown by previous However, due to logistic limitations and simultaneous experiments, studies of large seaweeds (e.g. Bischof et al., 1998; Connan et al., 2004; different equipments were used at each of the three sampling sites Rothäusler et al., 2011b; Gómez and Huovinen, 2011; Cruces et al., throughout the experiments (Coquimbo: PAM 2500, Walz, Effeltrich, 2012). Blade samples for in vivo chlorophyll a fluorescence of photo- Germany; Concepcion: MINI-PAM, Walz, Effeltrich, Germany; Punta system II (PSII) were processed immediately in the laboratory. Samples Arenas: DIVING-PAM, Walz, Effeltrich, Germany). Therefore, to visua- for pigments, soluble phlorotannins and antioxidant activity were lize how photosynthetic conditions changed at sinking time and con- frozen in liquid nitrogen, stored at −80 °C. Samples from Concepción sidering that different initial benthic values were observed among sites, and Pta. Arenas were then sent on dry ice to the central analysis la- finalv F /Fm values were expressed relative to the respective initial va- boratory at Universidad Católica del Norte in Coquimbo. lues (day 0). Considering the different technical characteristics of the equipments used (Figueroa et al., 2013), this transformation allowed 2.6. Response variables of benthic and floating bull kelps better comparability between experimental sites and seasons. From each benthic and sunken experimental thallus, a pool of three 2.6.1. Morphological and reproductive changes small blade disks was used for pigment extraction with N,N-di- The total wet weight and maximum length of all experimental bull methylformamide (DMF) for 24 h at 4 °C in darkness. The Chl a content kelps were measured at day 0 (initial benthic status) and on the (mg g−1 ww, wet weight) was calculated using the dichromatic

70 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79 equation from Inskeep and Bloom (1985); for this the absorbance of the biomass), and physiological performance, which included four vari- extracts was measured in a scanning UV–visible spectrophotometer ables (Fv/Fm, chlorophyll a, phlorotaninns, and antioxidant activity). In (Rayleigh, model UV-1601, China). The other pigments, Chl c and total all cases, the variables were standardized by the initial benthic tissue carotenoids, were also determined in the same extract, but considering biomass or physiological status and the floating time (% relative to that they showed a similar pattern of variation as Chl a these were not initial value d−1) because benthic kelps differed according to site and considered for the statistical analysis. season, and in floating time. The initial values were calculated fromthe The soluble phlorotannins were determined from successive ex- mean of the eight benthic thalli (day 0) for each site and season. Two- tractions (x 3) using the Folin-Ciocalteu method (Koivikko, 2008). way PERMANOVA tests were done considering site as random factor Lyophilized samples (∼10 mg) were homogenized with 3 mL of 70% (three levels) and season as fixed factor (two levels). The similarity acetone, stirred for 24 h at 4 °C. Subsequently, separation of the su- matrix for each PERMANOVA was obtained through the Euclidean pernatant was performed by centrifugation (BOECO, U-320R, Ger- distance with 9999 permutations. Then post-hoc pair-wise comparisons many) at 4500 rpm for 15 min and from the supernatant fraction 250 μL were used to explore significant factor effects using 9999 permutations. were mixed with 1250 mL of distilled water, 500 μL of Folin-Ciocalteu, After each PERMANOVA, a Similarity Percentage (SIMPER) routine was

1000 μL 1 N, and 20% Na2CO3. The solution was incubated in the dark applied to verify the contribution of each biomass or physiological for 45 min and centrifuged for 3 min at 4500 rpm. This procedure was variable to the differences for each factor. This was done via astan- repeated three times and the absorbance was measured at 730 nm in a dardized (normalized) data matrix, using a 90-percentage cut-off, as UV–visible spectrophotometer (Rayleigh, model UV-1601, China). The well as the average dissimilarity between levels of each factor. The values were calculated in mg phlorotannins g−1 dw (dry weight) using analyses were done using the statistical package PRIMER v7 (Clarke Phloroglucinol (Sigma-Aldrich) as standard. et al., 2014). When the PERMANOVA revealed significant effects of The radical scavenging activity was evaluated by the 2,2-diphenyl- each factor, response variables were analysed individually with two- 1-picrylhydrazyl (DPPH) method (Brand-Williams et al., 1995). The way ANOVA considering site (three levels), season (two levels), and fresh tissue sample powdered in nitrogen (∼240 mg ww) was extracted their interactions (site x season) as factors. Normality of data and with 1 mL 70% ethanol at 50 °C for 60 min (homogenized every homoscedasticity of variance were verified using Kolmogorov-Smirnov 15 min). 300 μL of the algal extract were mixed with 700 μL DPPH statistics and Levene tests, respectively. Since data distribution within (50 mg L−1 70% methanol), and the decay of absorbance was measured factors often violated normality assumptions and transformation failed, at 0 and 30 min at 523 nm in an UV–visible spectrophotometer (Ray- a conservative confidence level of 99% was used (Underwood, 1997). leigh, model UV-1601, China). The percentage of radical scavenging Significant differences between factors were evaluated using aTukey activity was calculated from the consumption of DPPH using formula HSD test (α = 0.01).

[1−(Am/Ao)] × 100, where Am represents the absorbance of extract in The frequency of the maturity stage of the initial benthic (n = 8) solution after reaction with DPPH (at final time), and Ao is the absor- and experimental bull kelps at the time of sinking were analysed ap- bance at time 0 (Molyneux, 2004). plying a log-linear model considering the factors status (benthic vs. sunken thallus), locality, season, and their interactions (Quinn and 2.7. Statistical analyses Keough, 2002). The Generalized linear model (GLM) with only the significant factors was glm (mature ∼ status + season + offset (log To determine whether the sizes of experimental thalli differed be- (total )), data = R2, family = poisson). All analyses were per- tween sites (Coquimbo, Concepción and Pta. Arenas) and seasons formed using the R software v3.4. (R Development Core Team, 2018). (winter and summer), the total wet weight and maximum length of the experimental D. antarctica were compared with two-way ANOVA. The 3. Results weight and length data were log-transformed before being analysed to comply with requirements of normality and homoscedasticity. When 3.1. Environmental conditions during the study the ANOVA revealed significant differences, a post-hoc Tukey's HSD test was applied. Normality was verified using Shapiro–Wilk's statistic Clear latitudinal and seasonal differences in local seawater tem- and homoscedasticity of variance by using Levene tests (Underwood, peratures and PAR were observed during the experiments. Lowest mean 1997; Zar, 2010). Environmental conditions in each experimental zone temperatures were registered in winter and at high latitudes and then were only analysed descriptively. increased towards the summer at all localities (Fig. 2). Higher varia- Floating persistence (days) curves by site and season were analysed bility in daily temperatures was detected during summer, especially in using Kaplan-Meier survival analysis with a confidence level of 95%. Concepción and at the end of the summer in Pta. Arenas. Monthly PAR The six Kaplan-Meier survival curves were compared with the Peto- showed a similar tendency as temperature, with high levels at low Wilcoxcon test. The survival analysis was done using the R software (Coquimbo) and mid latitudes (Concepción), especially during winter v3.4, “survival” package (R Development Core Team, 2018). and spring month. During early summer, similar PAR levels were de- The total biomass and length changes per day (% d−1) of sunken tected in the three experimental zones independent of latitude (Fig. 2). bull kelps were analysed with two-way ANOVA, separately for each During the experiments, the essential nutrients (N and P) were variable (biomass, length). The factors site (Coquimbo, Concepción and present in the experimental areas but concentrations were variable and Pta. Arenas) and season (winter and summer) were considered as fixed depended on site, season and type of nutrient (Table S3). Higher con- and a post-hoc Tukey's HSD was applied when the ANOVA revealed centrations of phosphate were detected in summer for the three ex- significant differences. For the analyses, the constant 10 was addedto perimental sites, while lower concentrations of nitrate were measured each rate of daily percent biomass change to make them non-negative in Pta. Arenas in both seasons (Table S3). to allow log transformation (McDonald, 2014). The normality was verified using Shapiro–Wilk's statistic and the homoscedasticity of 3.2. Floating persistence of bull kelps variance by using Levene tests, respectively. A permutational multivariate analysis of variance (PERMANOVA; The survival of floating kelps significantly differed (P < 0.05) Anderson, 2001) was applied in order to examine whether experimental among sites, seasons and all pairwise combinations (Table 1). Rapid site (Coquimbo, Concepción and Pta. Arenas) and season (winter and sinking was observed at the low latitude site (Coquimbo) with the first summer) had an effect on the response variables of floating kelps atthe sunken thallus before 20 days. For thalli set afloat in the summer ex- time of sinking. The responses measured on the sunken kelps included periment, the maximum floating time was short and almost half ofthe tissue biomass changes with three variables (fronds, stipes, and holdfast experimental bull kelps had sunk after 30 days at both low and mid

71 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

Fig. 2. Average of (A) daily seawater temperature (STT), and (B) monthly photosynthetically active radiation (PAR) from July 2014 (austral winter) and March 2015 (end of summer). In the temperature plot (A), vertical dark and light grey bars mark the floating persistence of D. antarctica set afloat in winter and summer experiments, respectively.

latitude sites. Maximum floating persistence of D. antarctica was ob- Table 1 served at the high latitude site (Pta. Arenas) where the experimental Single comparisons of the survival curves (Peto-Wilcoxon test) of floating D. kelps floated for up to 203 days in winter and 90 days in summerex- antarctica. The analysis included a comparison among sites (Cq = Coquimbo; periments (Table S1b). During the last experimental summer floating Co = Concepción; Pa = Pta. Arenas) within each season (W = winter; bull-kelps in Concepción and Pta. Arenas sank after days with high S = summer) and between seasons within each locality. seawater temperature (Fig. 2). FACTORS X2 df P-value

WINTER (overall) 28.9 2 < 0.001 3.3. Performance of biomass, reproductive and physiological characteristics Cq x Co 18.6 1 < 0.001 Cq x Pa 13.3 1 < 0.001 Co x Pa 9.8 1 < 0.001 The analysis of PERMANOVA showed significant differences (P < 0.01) among sites and the interaction site x season (Table 2). SUMMER (overall) 65.3 2 < 0.001 Floating kelps from Coquimbo and Concepción were significantly Cq x Co 15.4 1 < 0.001 Cq x Pa 44.2 1 < 0.001 (P < 0.01) different from those in Pta. Arenas, and the holdfast bio- Co x Pa 41.2 1 < 0.001 mass was the tissue that mostly contributed to these differences (Table 2). There were no significant differences between seasons. SITES (x season) However, the significant interaction (P < 0.01) showed that the dif- Coquimbo W x S 3.9 1 0.0487 ferences occurred in winter experiments between Coquimbo and Con- Concepción W x S 5.8 1 0.0163 Pta. Arenas W x S 9.5 1 0.0021 cepción and between Coquimbo and Pta. Arenas, and in summer ex- periments only between Concepción and Pta. Arenas (Table 2). The

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Table 2 Results of two-way PERMANOVA for response variables in sunken Durvillaea antarctica. Factors were experimental sites (Cq = Coquimbo; Co = Concepción; Pa = Pta. Arenas) and season (W = winter and S = summer). Pair-wise post-hoc comparisons were done on significant terms. Significant values (P < 0.01) are shownin bold. Pair-wise tests show site, season or site × season interaction that differed (P < 0.01). Non-significant pair-wise tests are not shown. The response variables included daily biomass change of frond, stipes and holdfast, and physiological performance of Fv/Fm, chlorophyll a, phlorotannins and antioxidant activity. The results of SIMPER analyses were done for each significant pairwise comparison and are indicated for the variable with the highest % dissimilarity contribution.

Source of df MS Pseudo F P-value Significant pair-wise comparisons variation

Site A 2 83.116 4.8347 0.0002 Cq ≠ Pa; Co ≠ Pa Season B 1 52.925 0.7482 0.5579 A x B 2 71.386 4.1524 0.0007 W [Cq ≠ Pa; Cq ≠ Co]S [Co ≠ Pa] Residuals 107 17.191

Pairwise comparisons SIMPER

df F P Tissue Dissimilarity Contribution (%)

Sites Cq × Co 1; 77 1.09 0.2916 Cq x Pa 1; 74 2.64 < 0.001 Holdfast (% d−1) 37.30 Co x Pa 1; 63 2.36 < 0.001 Holdfast (% d−1) 31.50

Seasons (Winter) Cq × Co 1; 34 2.92 < 0.001 Phlorotannins (% d−1) 35.11 Cq x Pa 1; 34 2.71 < 0.001 Frond (% d−1) 34.33 Co x Pa 1; 26 1.39 0.1178

Seasons (Summer) Cq × Co 1; 43 1.56 0.0646 Cq x Pa 1; 40 1.62 0.0659 Co x Pa 1; 37 2.31 < 0.001 Holdfast (% d−1) 43.05

SIMPER analysis revealed that different variables contributed to the 3.3.1. Biomass and length changes dissimilarity between sites, depending on season (Table 2). Changes in At the time of sinking thalli had lost biomass and became shorter at the physiological characteristics at the time of sinking showed a low all sites and in all seasons (Fig. 3). The biomass change presented sig- contribution to the differences among the factors. nificant effects (P < 0.01) for the factors site and season, while for daily length change significant effects (P < 0.01) were found for site and for the interaction site x season (Table 3). Daily biomass loss in Coquimbo was significantly (P < 0.01) higher than in Concepción and Pta. Arenas (Table 3, Fig. 3). In summer experiments, both low (Co- quimbo) and mid (Concepción) latitude sites showed high loss in thallus weight and length (Fig. 3). Changes in thallus length depended on site and season, with significantly (P < 0.01) higher losses at mid latitudes (Concepción) than at the other sites (Table 3). The losses in weight and length during floating conditions were also observed during thebi- weekly control of D. antarctica (Figs. S1 and S2). Only the floating bull kelps that were set afloat in winter at Pta. Arenas showed an increase in the total length during the first three months of the experiment ac- companied by minor changes in biomass (Figs. S1 and S2). The within-individual biomass distribution showed that the sunken thalli lost mostly frond and stipe tissues, whereas the holdfasts con- tributed positively to the changes in total biomass (Fig. 4). In the initial status (benthic thalli at day 0), frond tissues represented more than 60% of the total biomass, but in sunken thalli this proportion decreased to ∼50%. Frond tissues showed an important reduction in biomass especially for thalli set afloat at low latitudes (Coquimbo) in winter and at mid latitude (Concepción) in summer experiments (Fig. 4). Minor changes were observed in frond biomass in Pta. Arenas. Only the bio- mass changes in fronds were significantly (P < 0.01) affected by the interaction site x season (Table S4). No differences in daily biomass changes of stipes and holdfasts were detected between sites and seasons (Table S4, Fig. 4).

3.3.2. Reproductive maturity Benthic D. antarctica (initial status) showed a clear seasonal re- −1 Fig. 3. Daily total biomass and length change (% d ) of floating Durvillaea productive pattern with higher frequency of mature individuals during antarctica individuals (mean ± SD) from the start of the experiment to the day winter than in summer especially in Coquimbo and Concepción (Fig. 5). of sinking for thalli set afloat in winter 2014 and summer 2014/2015. Thallus status (initial benthic and sunken bull kelps) and season had

73 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

Table 3 Two-way ANOVA for biomass and length changes per day (% d−1) in sunken thalli of Durvillaea antarctica. Factors were site (Cq = Coquimbo, Co = Concepción, Pa = Pta. Arenas) and season (W = winter, S = summer). Significant P-values (< 0.01) are shown in bold. Pair-wise post-hoc comparisons (Tukey's HSD) show sites, seasons or interactions that differed (P < 0.05). Non-significant pair-wise tests are notshown.

Variable df MS F value P-value Significant pair-wise Source of variation comparisons

Daily biomass change Site A 2 0.051 15.046 < 0.001 Pa < Cq; Co < Cq Season B 1 0.029 8.520 0.004 W < S A x B 2 0.005 1.518 0.223 Residuals 118 0.003 Daily length change Site A 2 0.033 15.545 < 0.001 Pa < Co; Pa < Cq Season B 1 0.003 1.572 0.213 A x B 2 0.009 4.470 0.014 W [Pa < Co; Pa < Cq] S [Cq < Co; Pa < Co] Residuals 118 0.0003

significant effects (P < 0.01) on the frequency of mature thalli of D. Pta. Arenas (high latitude) (Fig. 5). antarctica (Pseudo-R2 = 0.988; Table S5). The proportion of mature individuals was substantially lower among sunken thalli than among 3.3.3. Physiological performance benthic thalli at all sites (Fig. 5). In summer experiments, mature Negative changes in the relative maximum quantum yield (Fv/Fm) sunken individuals were only observed in Coquimbo (low latitude) and and chlorophyll a concentrations were observed in sunken D. antarctica in both seasonal experiments and at all sites (Fig. 6A–B). The two-way ANOVA detected only significant (P < 0.01) differences for the inter- action site x season in chlorophyll a (Table S4). Summer conditions in Coquimbo and Concepción resulted in low chlorophyll a levels in sunken thalli compared to their initial benthic status (Fig. 6B). In contrast to the photosynthetic characteristics, phlorotannin con- centrations increased in sunken thalli, mainly in Coquimbo (winter) and Concepción (both seasons) with positive values (Fig. 6C). Minor changes were observed in Coquimbo (summer experiment) and both seasonal experiments in Pta. Arenas. Variations in antioxidant activity were minimal compared to the other studied variables (mean < 0.15% d−1). Positive changes indicating increases in antioxidant activity were observed in sunken thalli in Coquimbo (winter experiment) and in Pta. Arenas (summer experiment) (Fig. 6D). Both phlorotannin concentra- tions and antioxidant activity showed significant (P < 0.01) differ- ences only for the interaction between site x season (Table S4).

4. Discussion

Floating persistence and physiological acclimation of Durvillaea antarctica depended on latitude and season. At high latitudes this kelp floated for more than 200 days while at low latitudes it survived forless than 50 days at the sea surface. Summer conditions, accompanied by an increase in temperature and solar radiation, led to relatively shorter floating times at low and mid latitudes (20% shorter than in winter), which was even more pronounced at high latitudes (55% shorter floating times in summer than in winter). The proportion of thalli with mature conceptacles were reduced during long floating times, sup- pressing the colonization potential of kelp rafts. The relative increase in holdfast biomass compared to the buoyant frond biomass appears to be more important for sinking of floating D. antarctica than physiological changes.

4.1. Seasonal effect on floating persistence of bull kelps

Solar radiation and temperature are the main factors that provoke Fig. 4. Daily biomass change (% d−1) of fronds (A), stipes (B) and holdfasts (C) seasonal changes in biochemical and physiological traits impacting during the floating time of Durvillaea antarctica individuals (mean ± SD) for seaweed reproduction and growth (Kain, 1989; Falkowski and La thalli set afloat in winter 2014 and summer 2014/2015 experiments. Tissue Roche, 1991; Hurd et al., 2014). Seasonal changes in solar radiation are weight for each portion was standardized with respect to the average value dependent on latitude showing a difference of 50% between winter and obtained from the initial benthic thalli for each portion (day 0) and the floating summer conditions at low latitudes, whereas at high latitudes radiation time of each one. in summer can be 80% higher than in winter (Kain, 1989; Huovinen

74 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

continuous loss of tissue, especially in summer experiments. The loss of frond tissue, fundamental for buoyancy, mainly contributed to these negative changes. Similar results have been described in floating Macrocystis pyrifera with rapid degradation and sinking under un- favorable environmental conditions, which can be accelerated by her- bivory and epibiont loads (Rothäusler et al., 2009, 2018; Graiff et al., 2016). We did not measure the epibiont load in our experiments, be- cause an overall weak epibiont cover was observed on the surface of fronds and holdfasts. Possibly, the continuous loss of the first cell layers of the fronds during prolonged floating times, prevented the estab- lishment of epibionts. Interestingly, the bi-weekly biomass control of floating bull kelps during the experiments allowed to detect increases in thallus length during the first three months in thalli set afloat in winter at highlati- tudes. During short-term floating time experiments (< 14d), D. ant- arctica was able to show positive growth in winter at high latitude despite the low light and temperature conditions (Tala et al., 2016). Lower or moderate temperatures can buffer negative effects of high solar radiation occurring in summer, whereas a deleterious combina- tions of high temperature and light can affect the tissue integrity and accelerate biomass losses, thereby compromising the floating capacity of buoyant kelps (Rothäusler et al., 2009; Graiff et al., 2013; Tala et al., 2016). Lowest growth rates have been reported under high light in- tensities and high temperatures in Ecklonia radiata, which contrasted with highest growth rates at low temperatures (Bearham et al., 2013). The negative effect of high temperature and solar radiation on photo- Fig. 5. Percentage of mature individuals of D. antarctica at day 0 (benthic) and synthesis and activation of photoprotective mechanisms (Cruces et al., at day of sinking for thalli set afloat during winter 2014 and summer 2014/15 experiments. Upper number represents the total number (mature and im- 2012, 2013) can be reflected in low biomass production. mature) of thalli controlled in each case. The morphological changes during floating were accompanied by minor changes in physiological traits such as maximum quantum yield, pigments and phlorotannins. The photobiological characteristics of D. et al., 2006). In summer conditions, the increase in solar radiation is antarctica (i.e. low saturation irradiance, high efficiency photosynth- accompanied by an extension of the light hours, and consequently the esis, and dynamic photoinhibition) are considered adaptations for ef- daily dose radiation can be higher at high than at low latitudes. These ficient light use (Gómez and Huovinen, 2011; Cruces et al., 2013), latitudinal differences in the summer-winter contrast in solar radiation which might be associated with the subantarctic origin of this species. A can explain the steeper drop in floating persistence (∼50%) for D. notorious decrease in photosynthetic performance (Fv/Fm and pig- antarctica set afloat in summer at high latitudes compared to lowand ments) was observed at the time of sinking especially in summer ex- mid latitudes (∼20%). Nevertheless, the experimental rafts of D. ant- periments at both low and mid latitudes. Similar changes in physiolo- arctica floated for substantially longer times at high latitudes thanat gical responses of floating D. antarctica had been described in previous mid or low latitudes during both seasonal experiments. long- (Graiff et al., 2013) and short-term experiments (Tala et al., Negative biomass and length changes during floating time indicate a 2016), as well as in M. pyrifera (Rothäusler et al., 2011b). During

Fig. 6. Daily change (% d−1) of relative maximal quantum yields (A), chlorophyll a concentration (B), Phlorotannin concentration (C), and antioxidant activity (D) during the floating time of Durvillaea antarctica for thalli set afloat in winter 2014 and in summer 2014/2015. Values were stan- dardized with respect to the initial mean value of benthic thalli and floating time.

75 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79 floating, the physiological acclimation of D. antarctica might be in- occur due to the breaking of larger frond pieces, some more deterio- sufficient to support growth and extend the persistence time, especially rated than others, which can float separately from the complete thallus in summer, when the accelerated tissue degradation of the buoyant for unknown times. Since these pieces (without a holdfast) exert a lower frond causes sinking of the kelp due to the heavy holdfast. drag force against currents, they might travel faster and over longer Seasonal metabolic performance and morphological changes during distances compared to a complete, heavier thallus (with holdfast). floating can also affect the reproductive potential of floating seaweeds. Moreover due to their smaller sizes, the tissue pieces can be constantly An important trait to consider after extensive floating journeys and in turned over at the sea surface facilitating photosynthetic recovery and species with short-range propagules (Santelices, 1990) is the ability to prolonged floating times (Tala et al., 2017). Large holdfasts, without remain reproductively competent upon arrival in new habitats. Durvil- floating capacity, would end up sinking thereby contributing todeep laea antarctica shows a strong seasonal reproductive pattern in benthic sea productivity (Krumhansl and Scheibling, 2012). (Santelices et al., 1980; Hay, 1994; Collantes et al., 1997, 2002; Although two divergent clades have been described for D. antarctica Mansilla et al., 2017) as well as in floating conditions (Tala et al., 2013, (Fraser et al., 2009, 2010), our results showed similar morphological 2016; Lizée-Prynne et al., 2016). Depending on latitude, gamete de- changes associated with loss of biomass and length in floating condi- velopment can begin in autumn and extend to early spring whereas in tions accompanied by slight variations in physiological traits such as summer the senescent stages predominate. As low sea surface tem- maximum quantum yield, pigments and phlorotannins at all latitudes. peratures favour the maturation and release of gametes (Hay, 1994) The differences in biochemical composition and ecophysiological traits more than one reproductive event could occur during prolonged between the two clades of D. antarctica were relatively minor, much floating times at high latitudes. However, a drastic reduction inthe smaller than differences observed between two congener kelp species of proportion of mature thalli observed at the moment of sinking limits the Lessonia (L. berteroana Montagne and L. spicata (Suhr) Santelices, availability of gametes for dispersal. When mature benthic bull kelps cryptic species of the Chilean coast) (Koch et al., 2015). In the case of are detached in winter (i.e. high reproductive frequency) and rafting Durvillaea, variations between thalli from Coquimbo and Concepción, journeys take more than 3 months, the conceptacles degrade from corresponding to the same clade, were also observed in some mor- mature to senescent stages losing their reproductive potential. Thus, phological and physiological traits as part of the environmental local rafting may suppress the availability of gametes, further reducing the acclimation. Consequently, we infer that both clades have the ability to potential of successful fertilization between floating and resident bull acclimate to environmental variables in very similar ways and thus the kelps. observed differences in floating persistence are due to differences in environmental conditions rather than to possible functional differences 4.2. Latitudinal effect on floating persistence of bull kelps between the two genetic clades. In this sense, even though the sub- antarctic region provides favourable environmental conditions, the The persistence and performance of floating D. antarctica depended rapid decrease in floating persistence at high latitudes in summer, si- on the latitudinal conditions, and in almost all studied variables their milar to what has been observed at low and mid latitudes reinforces the responses were determined by the interaction between latitude and importance of environmental factors (i.e. temperature, solar radiation), season. Environmental conditions at high latitudes favour an extended affecting tissue integrity and floating persistence more than the biolo- floating persistence, which decrease towards low latitudes. However, gical/functional differences that could exist between the clades. latitudinal differences in solar radiation and temperature are more The records of D. antarctica pieces on Antarctic coasts, thousands of pronounced in winter than in summer affecting physiology and growth km from the nearest source populations (i.e. by molecular analysis) patterns in seaweeds (Kain, 1989). During summer, a sudden increase (Fraser et al., 2018) reinforce the importance of our study, identifying in seawater surface temperature coincided with fast sinking of the last the physiological traits that facilitate the high floating capacity of bull floating experimental thalli at high and mid latitudes (see Fig. 2) kelps at high latitudes. The contribution of floating kelps to population showing the importance of seawater temperature over floating persis- connectivity of the kelp itself and of epibionts between distant coasts tence and tissue integrity. has been based only on molecular studies and more recently integrating The capacity of floating kelps to persist for long time periods at high ecological and geological assessments (Waters et al. 2018). Our results latitudes is concordant with the common abundance of floating kelps in strongly support the hypothesis that the floating capacity of D. antarc- the subantarctic and cold regions of the southern hemisphere (Smith, tica is substantially higher at high than low and mid latitudes. 2002; Hinojosa et al., 2011; Wichmann et al., 2012; Fraser et al., 2017). At low and mid latitudes, the floating persistence of D. antarctica is 4.3. Implications for long-distance dispersal of floating seaweeds limited mainly in summer as had been previously described by Graiff et al. (2013) and Tala et al. (2013), and also for the floating kelp M. Abundant individual or group rafts of D. antarctica are widespread pyrifera (Rothäusler et al., 2011b; Graiff et al., 2016). Although some in the Southern Ocean, connecting adjacent and distant populations specimens of floating D. antarctica have been found beyond the (Smith, 2002; Fraser et al., 2017, 2018). Herein environmental factors northern distribution limit (∼30°S) of this species (Tala et al., 2013; such as temperature and solar radiation (depending on latitude and/or López et al., 2017), only some of them showed long floating times based season) were shown to affect persistence of kelps at the sea surface. on sizes and frequency of stalked barnacles Lepas spp. The low floating Although the floating time persistence can be extensive, oceanographic persistence of D. antarctica can explain the low genetic connectivity of and climatic factors such as strong surface winds and current velocity bull kelp populations in that area (Fraser et al., 2010). can enhance either dispersal or retention of floating kelps (Poulain At high latitudes sunken thalli showed minimum changes in pho- et al., 2009; Waters and Craw, 2018). Therefore, how far the floating tosynthetic traits and phlorotannins, and an increase in antioxidant kelps can be dispersed depends on a combination of multiple factors capacity in summer experiments in contrast to low and mid latitudes. that create an interaction between their acclimation potential and the Also in short-term experiments (< 14d), the floating kelps were able to environmental pressures at the sea surface. The Antarctic Circumpolar maintain high antioxidant capacity and a latitudinal gradient was ob- Current flows west-to-east around Antarctica with surface current served in biomass and physiological responses (Tala et al., 2016). Even speeds of 0.1–0.6 m s−1 (Meredith et al., 2011). Depending on the though physiological acclimation might be occurring in each experi- speed and thallus size, the maximum floating time of 210 days found at mental zone, accelerated tissue disintegration, especially of photo- high latitudes during winter can involve a travel between 1,000 (low synthetic tissue (fronds), causes enhanced fragmentation of the thallus, speed) to 10,000 km (high speed). This estimate supports again the thereby limiting its floating time. In this sense, the loss of biomass could hypothesis that the high acclimation potential of D. antarctica at high

76 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79 latitudes with more benign environmental (i.e. lower temperature) fa- between trans-oceanic populations of Capreolia implexa (Gelidiales, Rhodophyta) in vours long-term floating persistence and enhances the possibility of cool temperate waters of Australasia and Chile. Aquat. Bot. 119, 73–79. Brand-Williams, W., Cuvelier, M., Berset, C., 1995. Use of a free radical method to LDD. evaluate antioxidant activity. Food Sci. Biotechnol. 28, 25–30. The differential floating persistence observed in our study could also Camus, P.A., 2001. Biogeografía marina de Chile continental. Rev. Chil. Hist. Nat. 74 (3), contribute to understand the spatio-temporal variability in the abun- 587–617. Clarke, K.R., Gorley, R.N., Somerfield, P.J., Warwick, R.M., 2014. Change in Marine dance of floating rafts (Hinojosa et al., 2010; López et al., 2017, 2019) Communities: an Approach to Statistical Analysis and Interpretation, 3nd edition. and the heterogeneous genetic structure (Fraser et al., 2009, 2010) PRIMER-E, Plymouth, UK, pp. 172. described for D. antarctica along the continental coast of Chile. Lower Collantes, G., Riveros, R., Acevedo, M., 1997. Fenología reproductiva de Durvillaea ant- floating persistence at low and mid latitudes and especially in summer arctica (Phaeophyta, Durvillaeales) del intermareal de caleta Montemar, Chile cen- tral. Rev. Biol. Mar. Oceanogr. 32, 111–116. conditions restrict the potential for LDD, limiting connectivity between Collantes, G., Merino, A., Lagos, V., 2002. Fenología de la gametogénesis, madurez de populations. At higher latitudes, the longer floating persistence can conceptáculos, fertilidad y embriogénesis en Durvillaea antarctica (Chamizo) Hariot favour LDD and transoceanic dispersal with high abundance of floating (Phaeophyta, Durvillaeales). Rev. Biol. Mar. Oceanogr. 37, 83–112. Connan, S., Goulard, F., Stiger, V., Deslandes, E., Ar, G.E., 2004. Interspecific and tem- thalli, thereby contributing to the homogenous genetic structure of bull poral variation in phlorotannin levels in an assemblage of . Bot. Mar. 47, kelp populations in the subantarctic region. 410–416. Coyer, J.A., Hoarau, G., Van Schaik, J., Luijckx, P., Olsen, J.L., 2011. Trans-Pacific and trans-Arctic pathways of the intertidal macroalga Fucus distichus L. reveal multiple Authors' contributions glacial refugia and colonizations from the North Pacific to the North Atlantic. J. Biogeogr. 38, 756–771. FT, AM, ECM and MT conceived the idea; FT, MV, RJ and JO col- Cruces, E., Huovinen, P., Gómez, I., 2012. Phlorotannin and antioxidant responses upon short-term exposure to UV radiation and elevated temperature in three south pacific lected the data; analyses were conducted by FT, MV, and BAL; FT, BAL kelps. Photochem. Photobiol. 88, 58–66. and MT led the writing with assistance from MV, ECM, AM, RJ and JO. Cruces, E., Huovinen, P., Gómez, I., 2013. Interactive effects of UV radiation and en- hanced temperature on photosynthesis, phlorotannin induction and antioxidant ac- tivities of two sub-Antarctic brown algae. Mar. Biol. 160, 1–13. Conflicts of interest Cumming, R.A., Nikula, R., Spencer, H.G., Waters, J.M., 2014. Transoceanic genetic si- milarities of kelp-associated sea slug populations: long-distance dispersal via rafting? We have no competing interests. J. Biogeogr. 41, 2357–2370. Falkowski, P.G., LaRoche, J., 1991. Acclimation to spectral irradiance in algae. J. Phycol. 27, 8–14. Funding Figueroa, F.L., Jerez, C.G., Korbee, N., 2013. Use of in vivo chlorophyll fluorescence to estimate photosynthetic activity and biomass productivity in microalgae grown in The research was supported by FONDECYT (Chile) grant 1131023 different culture systems. Lat. Am. J. Aquat. Res. 41, 801–819. Försterra, G., 2009. Ecological and biogeographical aspects of the Chilean Fjord region. to FT, MT, ECM and AM., CONICYT PAI (Chile) 79160069 to FT, and In: Häussermann, V., Försterra, G. (Eds.), Marine Benthic Fauna of Chilean Patagonia. PhD-fellowship Beca CONICYT-PCHA/DoctoradoNacional/ Nature in Focus, Puerto Montt, pp. 61–76. 2014–21140010 to BL. Fraser, C.I., Waters, J.M., 2013. Algal parasite Herpodiscus durvillaeae (Phaeophyceae: sphacelariales) inferred to have traversed the pacific ocean with its buoyant host. J. Phycol. 49, 202–206. Acknowledgements Fraser, C.I., Nikula, R., Spencer, H.G., Waters, J.M., 2009. Kelp genes reveal effects of subantarctic sea ice during the last glacial maximum. Proc. Natl. Acad. Sci. Unit. States Am. 106, 3249–3253. We gratefully thank Vieia Villalobos and Alvaro Villena, for their Fraser, C.I., Thiel, M., Spencer, H., Waters, J., 2010. Contemporary habitat discontinuity invaluable help and assistance in the field and laboratory procedures. and historic glacial ice drive genetic divergence in Chilean kelp. BMC Evol. Biol. 10, Also we thank the undergraduate students from our universities in 203–214. Fraser, C.I., Nikula, R., Waters, J.M., 2011. Oceanic rafting by a coastal community. Proc. Coquimbo, Concepción and Pta. Arenas for their help in the different Roy. Soc. Lond. Ser. Biol. Sci. 278, 649–655. activities. We are also grateful to Dr. Carlos Lara (CIRENYS, Fraser, C.I., Zuccarello, G.C., Spencer, H.G., Salvatore, L.C., Garcia, G.R., Waters, J.M., Universidad Bernardo O'Higgins, Chile) to provide solar radiation in- 2013. Genetic affinities between trans-oceanic populations of non-buoyant macro- formation. Valuable comments by two anonymous reviewers also algae in the high latitudes of the Southern Hemisphere. PLoS One 8 (7), e69138. Fraser, C.I., Kay, G.M., de Plessis, M., Ryan, P.G., 2017. Breaking down the barrier: dis- helped to improve the final version of the manuscript. Finally, we thank persal across the Antarctic Polar. Front. Ecography 40, 235–237. the support of Servicio Hidrográfico de la Armada de Chile (SHOA- Fraser, C.I., Morrison, A.K., Hogg, A.McC., Macaya, E.C., van Sebille, E., Ryan, P.G., CENDHOC). Padovan, A., Jack, C., Valdivia, N., Waters, J.M., 2018. Antarctica's ecological iso- lation will be broken by storm-driven dispersal and warming. Nat. Clim. Change 8, 704–708. Appendix A. Supplementary data Gillespie, R.G., Baldwin, B.G., Waters, J.M., Fraser, C.I., Nikula, R., Roderick, G.K., 2012. Long-distance dispersal: a framework for hypothesis testing. Trends Ecol. Evol. 27, 47–56. Supplementary data to this article can be found online at https:// González-Wevar, C.A., Segovia, N.I., Rosenfeld, S., Ojeda, J., Hüne, M., Naretto, M., doi.org/10.1016/j.marenvres.2019.05.013. Saucède, T., Brickle, P., Morley, S., Féral, J., Spencer, H.G., Poulin, E., 2018. Unexpected absence of island endemics: long-distance dispersal in higher latitude sub-Antarctic Siphonaria (Gastropoda: euthyneura) species. J. Biogeogr. 45, 874–884. References Guillemin, M.L., Valero, M., Faugeron, S., Nelson, W., Destombe, C., 2014. Tracing the trans-pacific evolutionary history of a domesticated seaweed (Gracilaria chilensis) Anderson, M.J., 2001. A new method for non-parametric multivariate analysis of var- with archaeological and genetic data. PLoS One 9 (12), e114039. iance. Austral Ecol. 26, 32–46. Guillemin, M.L., Valero, M., Tellier, F., Macaya, E.C., Destombe, C., Faugeron, S., 2016. Batista, M.B., Batista, A., Franzan, P., Simionatto, P., Lima, T.C., Velez-Rubio, G.M., Phylogeography of seaweeds in the south east pacific: complex evolutionary pro- Scarabino, F., Camacho, O., Schmitz, C., Martinez, A., Ortega, L., Fabiano, G., cesses along a latitudinal gradient. In: Hu, Z.-M., Fraser, C. (Eds.), Seaweed Rothman, M.D., Liu, G., Ojeda, J., Mansilla, A., Barreto, L.M., Assis, J., Serrão, E.A., Phylogeography, pp. 251–278. Santos, R., Horta, P.A., 2018. Kelps' long-distance dispersal: role of ecological/ Gómez, I., Huovinen, P., 2011. Morpho-functional patterns and zonation of South Chilean oceanographic processes and implications to marine forest conservation. Diversity seaweeds: the importance of photosynthetic and bio-optical traits. Mar. Ecol. Prog. 10, 11. Ser. 422, 77–91. Bearham, D., Vanderklift, M.A., Gunson, J.R., 2013. Temperature and light explain spatial Graiff, A., Karsten, U., Meyer, S., Pfender, D., Tala, F., Thiel, M., 2013. Seasonal variation variation in growth and productivity of the kelp Ecklonia radiata. Mar. Ecol. Prog. Ser. in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli. Bot. 476, 59–70. Mar. 56, 3–14. Bischof, K., Hanelt, D., Tüg, H., Karsten, U., Brouwer, P.E.M., Wiencke, C., 1998. Graiff, A., Pantoja, J.E., Tala, F., Thiel, M., 2016. Epibiont load causes sinking ofviable Acclimation of brown algal photosynthesis to ultraviolet radiation in Arctic coastal kelp rafts: seasonal variation in floating persistence of giant kelp Macrocystis pyrifera. waters (Spitsbergen, Norway). Polar Biol. 20, 388–395. Mar. Biol. 163, 191–205. Blake, C., Thiel, M., López, B.A., Fraser, C.I., 2017. Gall-forming protistan parasites infect Gutow, L., Giménez, L., Boos, K., Saborowski, R., 2009. Rapid changes in the epifaunal southern bull kelp across the Southern Ocean, with prevalence increasing to the community after detachment of buoyant benthic macroalgae. J. Mar. Biol. Assoc. U. south. Mar. Ecol. Prog. Ser. 583, 95–106. K. 89, 323–328. Boo, G.H., Mansilla, A., Nelson, W., Bellgrove, A., Boo, S.M., 2014. Genetic connectivity Gutow, L., Long, J.D., Cerda, O., Hinojosa, I., Rothäusler, E., Tala, F., Thiel, M., 2012.

77 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

Herbivosous amphipods inhabit protective microhabitats within thalli of giant kelp Biol. Rev. Camb. Philos. Soc. 92, 2164–2181. Macrocystis pyrifera. Mar. Biol. 159, 141–149. Nikula, R., Fraser, C.I., Spencer, H., Waters, J.M., 2010. Circumpolar dispersal by rafting Gutow, L., Beermann, J., Buschbaum, C., Rivadeneira, M.M., Thiel, M., 2015. Castaways in two subantarctic kelp-dwelling crustaceans. Mar. Ecol. Prog. Ser. 405, 221–230. can't be choosers - homogenization of rafting assemblages on floating seaweeds. J. Nikula, R., Spencer, H.G., Waters, J.M., 2013. Passive rafting is a powerful driver of Sea Res. 95, 161–171. transoceanic . Biol. Lett. 9, 20120821. Hay, C., 1994. Durvillaea (bory). In: Akatsuka, I. (Ed.), Biology of Economic Algae. SPB Poulain, P.-M., Gerin, R., Mauri, E., Pennel, R., 2009. Wind effects on drogued and un- Academic Publishing bv, The Hague, The Netherlands, pp. 353–384. drogued drifters in the eastern Mediterranean. J. Atmos. Ocean. Technol. 26, Haye, P.A., Segovia, N.I., Muñoz-Herrera, N.C., Gálvez, F.E., Martínez, A., Meynard, A., 1144–1156. Pardo-Gandarillas, M.C., Poulin, E., Faugeron, S., 2014. Phylogeographic structure in Quinn, G.P., Keough, M.J., 2002. Experimental Design and Data Analysis for Biologists. benthic marine invertebrates of the southeast Pacific coast of Chile with differing Cambridge University Press, Cambridge. dispersal potential. PLoS One 9, e88613. R Development Core Team, 2018. R: a language and environment forstatistical com- Hawes, N.A., Taylor, D.I., Schiel, D.R., 2017. Transport of drifting fucoid algae: nearshore puting. R Foundation for Statistical Computing, Vienna. http://www.r-project.org/. transport and potential for long distance dispersal. J. Exp. Mar. Biol. Ecol. 490, Ramírez, M.E., Santelices, B., 1991. Catálogo de las algas marinas bentónicas de la costa 34–41. temperada del Pacífico de Sudamérica Monografías Biológicas. pp. 1–437. Hernández-Carmona, G., Hughes, B., Graham, M., 2006. Reproductive longevity of Ramos-Rodríguez, A., Lluch-Cota, D.-B., Lluch-Cota, S.-E., Trasviña-Castro, A., 2012. Sea drifting kelp Macrocystis pyrifera (Phaeophyceae) in monterey Bay, USA. J. Phycol. surface temperature anomalies, seasonal cycle and trend regimes in the Eastern 42, 1199–1207. Pacific coast. Ocean Sci. 8, 81–90. Hinojosa, I.A., Pizarro, M., Ramos, M., Thiel, M., 2010. Spatial and temporal distribution Rothäusler, E., Gómez, I., Hinojosa, I.A., Karsten, U., Tala, F., Thiel, M., 2009. Effect of of floating kelp in the channels and fjords of southern Chile. Estuar. Coast ShelfSci. temperature and grazing on growth and reproduction of floating Macrocystis spp. 87, 367–377. (Phaephyceae) along a latitudinal gradient. J. Phycol. 45, 547–559. Hinojosa, I.A., Rivadeneira, M., Thiel, M., 2011. Temporal and spatial distribution of Rothäusler, E., Gómez, I., Hinojosa, I.A., Karsten, U., Miranda, L., Tala, F., Thiel, M., floating objects in coastal waters of central-southern Chile and Patagonian fjords. 2011a. Kelp rafts in the Humboldt Current: interplay of abiotic and biotic factors Cont. Shelf Res. 31, 172–186. limit their floating persistence and dispersal potential. Limnol. Oceanogr. 56, Hobday, A.J., 2000. Abundance and dispersal of drifting kelp Macrocystis pyrifera rafts in 1751–1763. the Southern California Bight. Mar. Ecol. Prog. Ser. 195, 101–116. Rothäusler, E., Gómez, I., Karsten, U., Tala, F., Thiel, M., 2011b. Physiological acclima- Huovinen, P., Gómez, I., Lovengreen, C., 2006. A five-year study of solar ultraviolet ra- tion of floating Macrocystis pyrifera to temperature and irradiance ensures long-term diation in southern Chile (39 S): potential impact on physiology of coastal marine persistence at the sea surface at mid-latitudes. J. Exp. Mar. Biol. Ecol. 405, 33–41. algae? Photochem. Photobiol. 82, 515–522. Rothäusler, E., Gutow, L., Thiel, M., 2012. Floating seaweeds and their communities. In: Hurd, C.L., Harrison, P.J., Bischof, K., Lobban, C.S., 2014. Seaweed Ecology and Wiencke, C., Bischof, K. (Eds.), Seaweed Biology, Ecological Studies. Springer- Physiology, second ed. Cambridge University Press. Verlag., Berlin, pp. 359–380. Inskeep, W.P., Bloom, P.R., 1985. Extinction coefficients of chlorophyll a and b in N,N- Rothäusler, E., Reinwald, H., López, B.A., Tala, F., Thiel, M., 2018. High acclimation dimetylformamide and 80% acetone. Plant Physiol. 77, 483–485. potential in floating Macrocystis pyrifera to abiotic conditions even under grazing Kain, J.M., 1989. Season in the subtidal. Br. Phycol. J. 24, 203–215. pressure - a field study. J. Phycol. 54, 368–379. Koch, K., Thiel, M., Tellier, F., Hagen, W., Graeve, M., Tala, F., Laeseke, P., Bischof, K., Santelices, B., 1990. Patterns of reproduction, dispersal and recruitment in seaweeds. 2015. Species separation within the Lessonia nigrescens complex (Phaeophyceae, Oceanogr. Mar. Biol. Annu. Rev. 28, 177–276. Laminariales) is mirrored by ecophysiological traits. Bot. Mar. 58, 81–92. Santelices, B., Castilla, J.C., Cancino, J., Schmiede, P., 1980. Comparative ecology of Koivikko, R., 2008. Brown Algal Phlorotannins: Improving and Applying Chemical Lessonia nigrescens and Durvillaea antarctica (phaeophyta) in Central Chile. Mar. Biol. Methods. Ph.D. thesis, University of Turku, Turku, Finland. 19, 119–132. Kool, J.T., Moilanen, A., Treml, E.A., 2013. Population connectivity: recent advances and Schalatter, R.P., Riveros, G., 1987. Historia Natural del Archipiélago Diego Ramírez, new perspectives. Landsc. Ecol. 28, 165–185. Chile. Ser. Cient. INACH 47, 87–112. Krumhansl, K.A., Scheibling, R.E., 2012. Production and fate of kelp detritus. Mar. Ecol. Smith, S.D.A., 2002. Kelp rafts in the Southern Ocean. Glob. Ecol. Biogeogr. 11, 67–69. Prog. Ser. 467, 281–302. Smith, J.L., Summers, G., Wong, R., 2010. Nutrient and heavy metal content of edible Lizée-Prynne, D., López, B.A., Tala, F., Thiel, M., 2016. No sex-related dispersal limitation seaweeds in New Zealand. New Zeal. J. Crop Hort. 38, 19–28. in a dioecious, oceanic long-distance traveller: the bull kelp Durvillaea antarctica. Bot. Strickland, J.D.H., Parsons, T.R., 1972. second ed. A Practical Handbook of Seawater Mar. 59, 30–50. Analysis Bulletin 167 Fisheries Research Board of Canada, Ottawa. López, B.A., Macaya, E., Tala, F., Tellier, F., Thiel, M., 2017. The variable routes of Tala, F., Gómez, I., Luna-Jorquera, G., Thiel, M., 2013. Morphological, physiological and rafting: stranding dynamics of floating bull-kelp Durvillaea antarctica (Fucales, reproductive conditions of rafting bull kelp (Durvillaea antarctica) in northern-central Phaeophyceae) on beaches in the SE Pacific. J. Phycol. 55, 70–84. Chile (30°S). Mar. Biol. 160, 1339–1351. López, B.A., Macaya, E.C., Rivadeneira, M.M., Tala, F., Tellier, F., Thiel, M., 2018. Tala, F., Velásquez, M., Macaya, E., Mansilla, A., Thiel, M., 2016. Latitudinal and seasonal Epibiont communities on stranded kelp rafts of Durvillaea antarctica (Fucales, effects on short-term acclimation of floating kelp species from the South-East Pacific. Phaeophyceae) – do positive interactions facilitate range extensions? J. Biogeogr. 45, J. Exp. Mar. Biol. Ecol. 483, 31–41. 1833–1845. Tala, F., Penna, M., Luna, G., Rothäusler, E., Thiel, M., 2017. Daily and seasonal changes López, B.A., Macaya, E.C., Jeldres, R., Valdivia, N., Bonta, C.C., Tala, F., Thiel, M., 2019. of photobiological responses in floating bull kelp Durvillaea antarctica (Chamisso) Spatio-temporal variability of strandings of the southern bull kelp Durvillaea antarc- Hariot (Fucales: Phaeophyceae). Phycologia 56, 271–283. tica (Fucales, Phaeophyceae) on beaches on the coast of Chile - linking with local Tapia, F.J., Largier, J.L., Castillo, M., Wieters, E.A., Navarrete, S.A., 2014. Latitudinal storms. J. Appl. Phycol. https://doi.org/10.1007/s10811-018-1705-x. discontinuity in thermal conditions along the nearshore of central-northern Chile. Macaya, E., Boltaña, S., Hinojosa, I., Macchiavello, J., Valdivia, N., Vásquez, N., PLoS One 9 (10), e110841. Buschmann, A., Vásquez, J., Vega, A., Thiel, M., 2005. Presence of sporophylls in Thiel, M., Gutow, L., 2005a. The ecology of rafting in the marine environment. I. The floating kelp rafts of Macrocystis spp. (Phaeophyceae) along the Chilean Pacific coast. floating substrata. Oceanogr. Mar. Biol. Annu. Rev. 42, 181–263. J. Phycol. 41, 913–922. Thiel, M., Gutow, L., 2005b. The ecology of rafting in the marine environment. II. The Macaya, E.C., Zuccarello, G.C., 2010. Genetic structure of the giant kelp Macrocystis rafting organisms and community. Oceanogr. Mar. Biol. Annu. Rev. 43, 279–418. pyrifera along the southeastern Pacific. Mar. Ecol. Prog. Ser. 420, 103–112. Thiel, M., Macaya, E.C., Acuña, E., et al., 2007. The Humboldt Current System of Macaya, E.C., López, B., Tala, F., Tellier, F., Thiel, M., 2016. Float and raft: role of Northern and Central Chile: oceanographic processes, ecological interactions and buoyant seaweeds in the phylogeography and genetic structure of non-buoyant as- socioeconomic feedback. Oceanogr. Mar. Biol. 45, 195–344. sociated flora. In: Hu, Z.M., Fraser, C.I. (Eds.), Seaweed Phylogeography. Springer, Trovant, B., Orensanz, J.M., Lobo), Ruzzante, D.E., Stotz, W., Basso, N.G., 2015. Scorched Dordrecht, the Netherlands, pp. 97–130. mussels (Bivalvia: mytilidae: Brachidontinae) from the temperate coasts of South Mansilla, A.O., Avila, M., Cáceres, J., 2017. Reproductive biology of Durvillaea antarctica America: phylogenetic relationships, trans-Pacific connections and the footprints of (chamisso) Hariot in the sub-antartic ecoregion of magallanes (51–56°S). J. Appl. Quaternary glaciations. Mol. Phylogenetics Evol. 82, 60–74. Phycol. 29, 2567–2574. Underwood, A.J., 1997. Experiments in Ecology. Their Logical Design and Interpretation Méndez, F., Marambio, J., Ojeda, J., Rosenfeld, S., Rodríguez, J.P., Tala, F., Mansilla, A., Using Analysis of Variance. Cambridge University Press, Cambridge, UK. 2019. Variation of the photosynthetic activity and pigment composition in two Vandendriessche, S., Vincx, M., Degraer, S., 2007. Floating seaweed and the influences of morphotypes of Durvillaea antarctica (Phaeophyceae) in the sub-Antarctic ecoregion temperature, grazing and clump size on raft longevity a microcosm study. J. Exp. of Magallanes, Chile. J. Appl. Phycol. 31, 905–913. Mar. Biol. Ecol. 343, 64–73. Meredith, M.P., Woodworth, F.L., Chereskin, T.K., Marshall, D.P., Allison, L.C., Bigg, G.R., van Hees, D.H., Olsen, Y.S., Mattio, L., Ruiz‐Montoya, L., Wernberg, T., Kendrick, G.A., Donohue, K., Heywood, K.J., Hughes, C.W., Hibbert, A., McC.Hogg, M., Johnson, 2019. Cast adrift: physiology and dispersal of benthic Sargassum spinuligerum in H.L., Jullion, L., King, B.A., Leach, H., Lenn, Y.-D., Morales, M.A., Munday, D.R., surface rafts. Limnol. Oceanogr. 64, 526–540. Naveira, A.C., Provost, C., Sallée, J.-B., Sprintall, J., 2011. Sustained monitoring of Varela, A., Haye, P., 2012. The marine brooder Excirolana braziliensis (Crustacea: isopoda) the Southern Ocean at Drake Passage: past achievements and future priorities. Rev. is also a complex of cryptic species on the coast of Chile. Rev. Chil. Hist. Nat. 85, Geophys. 49, RG4005. 495–502. McDonald, J.H., 2014. Handbook of Biological Statistics, third ed. Sparky House Véliz, D., Winkler, F.M., Guisado, C., 2003. Developmental and genetic evidence for the Publishing, Baltimore, Maryland. existence of three morphologically cryptic species of Crepidula in northern Chile. Mar. McKenzie, P.F., Bellgrove, A., 2008. Dispersal of Hormosira banksii (Phaeophyceae) via Biol. 143, 131–142. detached fragments: reproductive viability and longevity. J. Phycol. 44, 1108–1115. Vernet, M., Diaz, S., Fuenzalida, H., Camilion, C., Booth, C.R., Cabrera, S., Casiccia, C., Molyneux, P., 2004. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for Deferrari, G., Lovengreen, C., Paladini, A., Pedroni, J., Rosales, A., Zagarese, H., estimating antioxidant activity. J. Sci. Technol. (Peshawar) 26, 211–219. 2009. Quality of UVR exposure for different biological systems along a latitudinal Moon, K., Chown, S.L., Fraser, C.I., 2017. Reconsidering connectivity in the sub-Antarctic. gradient. Photochem. Photobiol. Sci. 8, 1329–1345.

78 F. Tala, et al. Marine Environmental Research 149 (2019) 67–79

Waters, J.M., Craw, D., 2018. Cyclone-driven marine rafting: storms drive rapid dispersal processes structure . Trends Ecol. Evol. 28, 78–85. of buoyant kelp rafts. Mar. Ecol. Prog. Ser. 602, 77–85. Wichmann, C.S., Hinojosa, I.A., Thiel, M., 2012. Floating kelps in Patagonian Fjords: an Waters, J.M., King, T.M., Fraser, C.I., Craw, D., 2018. An integrated ecological, genetic important vehicle for rafting invertebrates and its relevance for . Mar. and geological assessment of long-distance dispersal by invertebrates on kelp rafts. Biol. 159, 2035–2049. Frontiers of Biogeography 10 (3–4), e40888. Zar, J.H., 2010. Biostatistical Analysis, fifth ed. edn. Prentice-Hall, Inc, Upper Saddle Waters, J.M., Fraser, C.I., Hewitt, G.M., 2013. Founder takes all: density-dependent Rive, NJ, USA.

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