Effects of changes in number, identity and abundance of habitat-forming species on assemblages of rocky seashores

Maggi, Elena; Bertocci, Iacopo; Vaselli, Stefano; Benedetti‐Cecchi, Lisandro

doi:10.3354/meps07949

Cited by 52 publications

(43 citation statements)

References 91 publications

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“…O 'Connor & Crowe (2005) found that the identity of species of grazers was more important than their number in determining patterns of algal productivity, after controlling for changes in density. Similarly, Maggi et al (2009) performed a study on the effects of changes in composition of intertidal assemblages using an experimental design to separate the effects of species richness and identity, while controlling for variation in species abundance. Their results showed significant effects of changes in number and identity of habitat-forming species on other organisms, even though the magnitude and direction of these effects were determined by the abundance of manipulated species.…”

Section: Discussionmentioning

confidence: 99%

Habitat identity influences species−area relationships in heterogeneous habitats

Matias

Underwood²,

Hochuli³

et al. 2011

Mar. Ecol. Prog. Ser.

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Loss of habitat is commonly identified as a reduction in area (or patch size) and its effects are often investigated using species−area relationships to evaluate loss of biodiversity. In many habitats, however, area alone is not sufficient to explain the decline of populations because natural habitats are rarely homogeneous. In fact, reductions in the diversity of habitats (e.g. destruction of microhabitats) might have even greater effects on the diversity of assemblages. Although these are 2 well-known attributes of habitats (i.e. area and diversity), there have been few empirical studies that have attempted to separate their effects by experimental manipulation. Experiments were carried out to separate the effects of number, relative proportion and identity of patches of habitat using additive designs. Predictions were tested using assemblages of marine molluscs colonizing artificial mimics of macroalgal habitats on rocky intertidal platforms. Our experiments to disentangle different attributes of habitat heterogeneity showed that these are complex and highly interactive. In particular, not all heterogeneous habitats had the numbers of species expected from a simple species−area relationship. Instead, the presence of more species in heterogeneous habitats could, to a great extent, be explained by the presence or absence of particular types of sub-habitats and not just by patch size. The complexity we found in responses of assemblages to composition of heterogeneous habitats was not predicted and could not have been observed without appropriate manipulations of habitat composition. A mechanistic understanding of the associations between species and particular types of habitats is essential for better predictions of species' responses to loss of natural habitats.

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Section: Discussionmentioning

confidence: 99%

Habitat identity influences species−area relationships in heterogeneous habitats

Matias

Underwood²,

Hochuli³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…In contrast to our prediction, no effects of barnacle cover emerged on total MPB biomass (or maximum photosynthetic efficiency) at the lower latitude in spite of the higher thermal and desiccation stress characterizing southern sites in comparison to northern ones. Geographic variation in barnacle cover might have played a role in driving changes in the intensity of positive interactions (Irving & Bertness 2009, Maggi et al 2009). However, although mean barnacle cover was smaller in the South than in the North (see Table S1), significant differences among treatment levels at northern sites suggested that this was not the cause of the lack of effects at southern ones.…”

Section: Discussionmentioning

confidence: 99%

“…By creating habitats and modifying the environment, foundation species exert positive effects on a wide range of organisms (Bruno & Bertness 2001, Altieri & van de Koppel 2014 and references therein), thus setting the stage for an ecological network of interactions (Kéfi et al 2012). Relatively recent studies demonstrated that traits of the benefactor species, such as its density, can modify the strength of facilitation in aquatic systems (Irving & Bertness 2009, Maggi et al 2009). Our results showed that barnacles can facilitate MPB and littorinids through density-dependent positive effects resulting from the provision of suitable habitat and likely by ameliorating abiotic conditions on adjacent rock surfaces.…”

Section: Climatic Conditions Density Dependence Local Stressors Andmentioning

confidence: 99%

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Latitudinal- and local-scale variations in a rocky intertidal interaction web

Maggi¹,

Milazzo

Graziano³

et al. 2015

Mar. Ecol. Prog. Ser.

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Natural assemblages are structured by a complex combination of positive and negative interactions, and the relative importance of each interaction can vary across spatial scales. By using a simple interaction web (barnacles−grazers−microphytobenthos) in a rocky intertidal system, we tested the hypothesis that the relative strength of positive and negative interactions would vary as a function of different environmental stress between 2 latitudinal levels and local environmental conditions. We manipulated the cover of barnacles and the presence of limpets at 2 sites in northern and southern Italy and non-destructively examined the response of microphytobenthos (MPB) (photosynthetic biomass, F 0, and maximum efficiency, F v /F m ) and of its small-sized grazers (littorinids). At northern sites, a density-dependent facilitative effect of barnacles on F 0 was detected. The effect was likely due to the addition of favourable secondary habitat (i.e. barnacle shells) and amelioration of abiotic conditions to nearby rock. At southern sites, a positive effect of increasing barnacle cover was observed on littorinid density. The subsequent indirect trophic effect on F 0 , in addition to local nutrient input from anthropogenic activities, likely masked the positive effects of increasing cover of barnacles on F 0 at this latitude. No factors influenced F v /F m , suggesting a lack of changes in the relative abundance of MPB species. There was no effect of excluding herbivores at either latitude. Results suggest that species interactions supported by foundation species might be undermined by the concomitant action of temperature-related changes and local anthropogenic stressors, whose interactive effects are likely to become more severe with global climate change.

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“…These included articulated corallines (mostly Corallina elongata), coarsely branched algae, and non-manipulated filamentous algae (these filamentous algae appeared at later stages of succession, mainly as epiphytes of other organisms, even though they were characterized by fast growth rates). Two other species, the brown canopy-forming alga Cystoseira compressa and the mussel Mytilus galloprovincialis, were included in the univariate analyses even if they did not attain high cover on the experimental plates, because they are important habitat formers at the study site (Maggi et al 2009). Univariate analyses extended the mixed-effect model used for the multivariate case by including time as a predictor, so that the estimates of linear and quadratic rates of change in abundance of organisms (i.e., the slope of temporal trajectories of abundances) were compared among the different experimental conditions (i.e., at increasing levels of richness and abundance in factorial combinations).…”

Section: Sampling and Statistical Analysismentioning

confidence: 99%

Connell and Slatyer's models of succession in the biodiversity era

Maggi

Bertocci

Vaselli

et al. 2011

Ecology

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Abstract. Understanding how species interactions drive succession is a key issue in ecology. In this study we show the utility of combining the concepts and methodologies developed within the biodiversity-ecosystem functioning research program with J. H. Connell and R. O. Slatyer's classic framework to understand succession in assemblages where multiple interactions between early and late colonists may include both inhibitory and facilitative effects. We assessed the net effect of multiple species interactions on successional changes by manipulating the richness, composition, and abundance of early colonists in a low-shore assemblage of algae and invertebrates of the northwestern Mediterranean. Results revealed how concomitant changes in species richness and abundance can strongly alter the net effect of inhibitory vs. facilitative interactions on succession. Increasing richness of early colonists inhibited succession, but only under high levels of initial abundance, probably reflecting the formation of a highly intricate matrix that prevented further colonization. In contrast, increasing initial abundance of early colonists tended to facilitate succession under low richness. Thus, changes in abundance of early colonists mediated the effects of richness on succession.

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Effects of changes in number, identity and abundance of habitat-forming species on assemblages of rocky seashores

Cited by 52 publications

References 91 publications

Habitat identity influences species−area relationships in heterogeneous habitats

Habitat identity influences species−area relationships in heterogeneous habitats

Latitudinal- and local-scale variations in a rocky intertidal interaction web

Connell and Slatyer's models of succession in the biodiversity era

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