A COMPARISON OF DRAGON KELP, EUALARIA FISTULOSA, (PHAEOPHYCEAE) FECUNDITY IN URCHIN BARRENS AND NEARBY KELP BEDS THROUGHOUT THE ALEUTIAN ARCHIPELAGO 1 Matthew S. Edwards 2 Department of Biology, San Diego State University, San Diego, CA 92182, USA Brenda Konar School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA The Aleutian Archipelago coastal ecosystem has undergone a dramatic change in community compo- sition during the past two decades. Following the removal of 99% of the sea otters, Enhydra lutris, from the ecosystem, changes to the benthic commu- nities resulted in widespread losses to most of the region’s kelp beds and corresponding increases in the prevalence of urchin barrens. Within the urchin barrens, the few kelps that have remained are exposed to elevated light, nutrients and currents, all of which may enhance their physiological condition and thus result in greater fecundity. To explore this further, we examined patterns of sporophyte fecun- dity in the dominant canopy-forming kelp, Eualaria ﬁstulosa, in both urchin barrens and in nearby kelp beds at seven Aleutian Islands spanning a range of 800 km. We found that the average weight of E. ﬁs- tulosa sporophyll bundles was signiﬁcantly greater on sporophytes occurring in the urchin barrens than in the nearby kelp beds. Furthermore, the average number of zoospores released per cm 2 of sporo- phyll area was also signiﬁcantly greater in individu- als from the urchin barrens than the nearby kelp beds. When these two metrics were combined, our results suggest that individual E. ﬁstulosa sporo- phytes occurring in the urchin barrens may produce as many as three times more zoospores than individ- ual E. ﬁstulosa sporophytes occurring in the nearby kelp beds, and thus they may contribute dispropor- tionately to the following year’s sporophyte recruit- ment in both urchin barrens and the adjacent kelp beds. Key index words: Aleutian Archipelago; Eualaria ﬁstulosa; fecundity; kelp; urchin barren; zoospore Patterns of zoospore release in kelps (Phaeophy- ceae, Laminariales) vary considerably with the physi- cal and biological characteristics of their environment (Anderson and North 1967, Reed 1987, Reed et al. 1996, Graham 2003, Buschmann et al. 2004). For example, while some kelps synchro- nize zoospore release during periods of elevated hydrodynamic forces (e.g., Amsler and Neushul 1989, Reed et al. 1997), others release zoospores in response to seasonal changes in ocean nutrients, temperature and ⁄ or salinity (e.g., Reed et al. 1996, Buschmann et al. 2004). Still, zoospore release in other kelps can vary randomly at short (minutes to hours) time scales, but be tightly coupled with adult abundance at long (months to years) time scales (Graham 2003). Furthermore, this coupling between zoospore output and adult abundance can itself vary with kelp bed size and between the exte- rior and interior portions of the kelp bed due to differences in current ﬂow and wave energy attenua- tion (Graham 2000, Reed et al. 2004). This com- bined with differences in kelp photosynthetic performance and nutrient uptake that can occur between the middle and outside the kelp beds (e.g., Gerard 1984) can impact overall zoospore produc- tion by individual kelp sporophytes. Given that zoo- spore production plays an integral role in the subsequent generation’s sporophyte recruitment, identifying the processes that result in either increased local zoospore output and ⁄ or enhanced zoospore dispersal can be integral to understanding how kelp beds will recover following being lost or reduced by environmental perturbations. Unlike many marine organisms, such as benthic invertebrates, that possess long distance dispersal stages that develop over time in the plankton (e.g., Scheltema 1971), kelp zoospores are typically viable immediately upon release and can settle on the sea- ﬂoor within minutes, resulting in dispersal distances being limited to within a few meters of their parents (Reed et al. 1988, 1992, Santelices 1990, Gaylord et al. 2002). This can lead to deleterious problems associated with inbreeding among the resulting gametophytes and subsequent reduced fecundity in the following generation’s sporophytes (Raimondi et al. 2004). However, while zoospore dispersal may be most limited near the center of the kelp beds, dispersal at the bed margins or from isolated indi- viduals occurring outside the beds may be greater 1 Received 30 January 2012. Accepted 29 February 2012. 2 Author for correspondence: e-mail: edwards@sciences.sdsu.edu. J. Phycol. 47, ***–*** (2012) Ó 2012 Phycological Society of America DOI: 10.1111/j.1529-8817.2012.01139.x 1