The emergence of the biodiversity-ecosystem functioning debate in the last decade has renewed interest in understanding why some communities are more easily invaded than others and how the impact of invasion on recipient communities and ecosystems varies. To date most of the research on invasibility has focused on taxonomic diversity, i.e., species richness. However, functional diversity of the communities should be more relevant for the resistance of the community to invasions, as the extent of functional differences among the species in an assemblage is a major determinant of ecosystem processes. Although coastal marine habitats are among the most heavily invaded ecosystems, studies on community invasibility and vulnerability in these habitats are scarce. We carried out a manipulative field experiment in tide pools of the rocky intertidal to test the hypothesis that increasing functional richness reduces the susceptibility of macroalgal communities to invasion. We selected a priori four functional groups on the basis of previous knowledge of local species characteristics: encrusting, turf, subcanopy, and canopy species. Synthetic assemblages containing one, two, three, or four different functional groups of seaweeds were created, and invasion by native species was monitored over an eight-month period. Cover and resource availability in the assemblages with only one functional group showed different patterns in the use of space and light, confirming true functional differences among our groups. Experimental results showed that the identity of functional groups was more important than functional richness in determining the ability of macroalgal communities to resist invasion and that resistance to invasion was resource-mediated.

The Iberian Lynx Conservation Breeding Program follows a multidisciplinary approach, integrated within the National Strategy for the Conservation of the Iberian lynx, which is carried out in cooperation with national, regional and international institutions. The main goals of the ex situ conservation programme are to: (1) maintain a genetically and demographically managed captive population; (2) create new Iberian lynx Lynx pardinus freeranging populations through re-introduction. To achieve the first goal, the Conservation Breeding Program aims to maintain 85% of the genetic diversity presently found in the wild for the next 30 years. This requires developing and maintaining 60-70 Iberian lynx as breeding stock. Growth projections indicate that the ex situ programme should achieve such a population target by the year 2010. Once this goal is reached, re-introduction efforts could begin. Thus, current ex situ efforts focus on producing psychologically and physically sound captive-born individuals. To achieve this goal, we use management and research techniques that rely on multidisciplinary input and knowledge generated on species' life history, behaviour, nutrition, veterinary and health aspects, genetics, reproductive physiology, endocrinology and ecology. Particularly important is adapting our husbandry schemes based on research data to promote natural behaviours in captivity (hunting, territoriality, social interactions) and a stress-free environment that is conducive to natural reproduction.

The macroalgal assemblages at the low intertidal zone were studied at three localities on the north coast of Spain between 1977 and 2002. Two of these localities were invaded at the end of the 1980s by the brown seaweed Sargassum muticum (Yendo) Fensholt (Phaeophyta, Sargassaceae), whereas the third locality remained free of the invader. In 2002, distinct algal assemblages were noticed in invaded and noninvaded localities. No major changes were detected in the noninvaded locality. Apart from the obvious presence of S. muticum, the changes observed in the invaded localities included a significant reduction in abundance of the previous dominant species (the red alga Gelidium spinosum (S. G. Gmelin) P. C. Silva) as well as an increased number of species and diversity, increased primary productivity, and variations in the seasonal abundance patterns of some species. We speculate that the arrival of S. muticum had a negative effect on the dominant native G. spinosum, probably related to competition for light. This resulted in indirect positive effects on other species of the assemblage (such as Bifurcaria bifurcata R. Ross). Other small epiphytic opportunistic species might also have been benefited from the presence of S. muticum, because the invader has a rich associated epiphytic assemblage.

The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt on a low intertidal macroalgal assemblage was assessed at a semiexposed rocky shore in northern Spain between 2002 and 2004. Sargassum muticum plants were removed from the mature macroalgal assemblage and from those occurring along the successional process of the assemblage. Biomass, richness, diversity, and percentage cover of macroalgae in experimental plots were compared with unmanipulated controls. The effect of S. muticum removal on the macroalgal assemblage more than 2 years after the beginning of the experiment was negligible. Moreover, no differences between treatments were detected in the general patterns of succession. Only significant differences in S. muticum abundance were detected between treatments at the end of the experiment. We suggest that the low abundance of S. muticum at this intertidal level and its pseudoperennial life cycle may limit competition with native macroalgae. However, long-term removal experiments may be a more indicator of the impact of S. muticum at the upper limit of its vertical distribution.

The invasibility of a low intertidal macroalgal assemblage was experimentally tested from March 2003 to April 2004 at 1 locality in northern Spain. It was hypothesised that a community becomes more susceptible to invasion when there is an increase in the amount of key resources. A bifactorial ('nutrient supply' and 'macroalgal biomass removed') orthogonal experiment was designed with 3 levels in each factor (high, medium and control). Fertile plants of Sargassum muticum (Yendo) Fensholt were transplanted to each plot to simulate the arrival of an invader. The invasibility of the assemblage was quantified in the pre-(density of recruits) and post-settlement (percentage cover, size and density of S. muticum at the end of the experiment) phases of S. muticum's life cycle. Results supported the initial hypothesis. Both space availability and nutrient enrichment facilitated the establishment and spread of S. muticum in the experimental plots. Established S. muticum plants grew faster in enriched plots than in controls. Furthermore, different successional assemblages played different roles in resisting invasion as S. muticum's life cycle progressed. In the initial stage of the invasion, the Bifurcaria bifurcata canopy inhibited recruitment by S. muticum, whereas understory species did not have a significant effect on invasion success. In contrast, an increased survivorship of S. muticum beneath the canopy of B. bifurcata was observed in those plots where S. muticum had successfully recruited. This study shows that the invasibility of this low intertidal assemblage is mediated by a complex interaction of several resources acting at different stages during S. muticum's invasion.KEY WORDS: Sargassum muticum · Invasibility · Marine invasion · Nutrients · Disturbance · Bifurcaria bifurcata · Macroalgal assemblage Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 313: [85][86][87][88][89][90][91][92][93][94] 2006 On a world-wide basis, space and seawater inorganic nutrients are the limiting resources for macroalgae in most temperate systems (Chapman & Craigie 1977, Sousa 1985, and therefore, in the context of FRAT, one might expect them to have effects on the susceptibility of communities to invasion by alien species. It has been argued that disturbance facilitates invasion by reducing the abundance of competitors or by increasing resource levels (D'Antonio 1993), especially in intertidal habitats where disturbances are strong organising forces of the community structure (Dayton 1971). Nutrient availability is another important ecological factor regulating the structure of coastal macroalgal communities (Valiela et al. 1997, Benedetti-Cecchi et al. 2001, and several studies on terrestrial systems have shown its importance in determining a community's invasibility (see Davis et al. 2000). However, in spite of the growing number of studies assessing the effects of nutrient supply on algal community structure, the role of nutrient inputs on community invasibility has n...