Dataset Information

Habitat formation prevails over predation in influencing fouling communities.

ABSTRACT: Coastal human-made structures, such as marinas and harbors, are expanding worldwide. Species assemblages described from these artificial habitats are novel relative to natural reefs, particularly in terms of the abundance of nonindigenous species (NIS). Although these fouling assemblages are clearly distinctive, the ecosystem functioning and species interactions taking place there are little understood. For instance, large predators may influence the fouling community development either directly (feeding on sessile fauna) or indirectly (feeding on small predators associated with these assemblages). In addition, by providing refuges, habitat complexity may modify the outcome of species interactions and the extent of biotic resistance (e.g., by increasing the abundance of niche-specific competitors and predators of NIS). Using experimental settlement panels deployed in the field for 2.5 months, we tested the influence of predation (i.e., caging experiment), artificial structural complexity (i.e., mimics of turf-forming species), and their interactions (i.e., refuge effects) on the development of sessile and mobile fauna in two marinas. In addition, we tested the role of biotic complexity-arising from the habitat-forming species that grew on the panels during the trial-on the richness and abundance of mobile fauna. The effect of predation and artificial habitat complexity was negligible, regardless of assemblage status (i.e., native, cryptogenic, and nonindigenous). Conversely, habitat-forming species and associated epibionts, responsible for biotic complexity, had a significant effect on mobile invertebrates (richness, abundance, and community structure). In particular, the richness and abundance of mobile NIS were positively affected by biotic complexity, with site-dependent relationships. Altogether, our results indicate that biotic complexity prevails over artificial habitat complexity in determining the distribution of mobile species under low predation pressure. Facilitation of native and non-native species thus seems to act upon diversity and community development: This process deserves further consideration in models of biotic resistance to invasion in urban marine habitats.

SUBMITTER: Leclerc JC

PROVIDER: S-EPMC5756867 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Habitat formation prevails over predation in influencing fouling communities.

Leclerc Jean-Charles JC Viard Frédérique F

Ecology and evolution 20171130 1

Coastal human-made structures, such as marinas and harbors, are expanding worldwide. Species assemblages described from these artificial habitats are novel relative to natural reefs, particularly in terms of the abundance of nonindigenous species (NIS). Although these fouling assemblages are clearly distinctive, the ecosystem functioning and species interactions taking place there are little understood. For instance, large predators may influence the fouling community development either directly ...[more]

PMID: 29321887

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Project description:BackgroundMale sexually selected vocalisations generally contain both individuality and quality cues that are crucial in intra- as well as inter-sexual communication. As individuality is a fixed feature whereas male phenotypic quality changes with age, individuality and quality cues may be subjected to different selection pressures over time. Individuality (for example, morphology of the vocal apparatus) and quality (for example, body size and dominance status) can both affect the vocal production mechanism, inducing the same components of vocalisations to convey both kinds of information. In this case, do quality-related changes to the acoustic structure of calls induce a modification of vocal cues to identity from year to year? We investigated this question in fallow deer (Dama dama), in which some acoustic parameters of vocalisations (groans) code for both individuality and quality.ResultsWe carried out a longitudinal analysis of groan individuality, examining the effects of age and dominance rank on the acoustic structure of groans of the same males recorded during consecutive years. We found both age- and rank-related changes to groans; the minimum values of the highest formant frequencies and the fundamental frequency increased with the age of males and they decreased when males became more dominant. Both age- and rank-related acoustic parameters contributed to individuality. Male quality changed with age, inducing a change in quality-related parameters and thus, a modification of vocal cues to male individuality between years.ConclusionsThe encoding of individuality and quality information in the same components of vocalisations induces a tradeoff between these two kinds of signals over time. Fallow deer vocalisations are honest signals of quality that are not fixed over time but are modified dynamically according to male quality. As they are more reliable cues to quality than to individuality, they may not be used by conspecifics to recognize a given male from one year to another, but potentially used by both sexes to assess male quality during each breeding season.

Project description:A central assumption underlying the study of habitat selection is that selected habitats confer enhanced fitness. Unfortunately, this assumption is rarely tested, and in some systems, gradients of predation risk may more accurately characterize spatial variation in vital rates than gradients described by habitat selection studies. Here, we separately measured spatial patterns of both resource selection and predation risk and tested their relationships with a key demographic trait, adult female survival, for a threatened ungulate, woodland caribou (Rangifer tarandus caribou Gmelin). We also evaluated whether exposure to gradients in both predation risk and resource selection value was manifested temporally through instantaneous or seasonal effects on survival outcomes. We used Cox proportional hazards spatial survival modelling to assess the relative support for 5 selection- and risk-based definitions of habitat quality, as quantified by woodland caribou adult female survival. These hypotheses included scenarios in which selection ideally mirrored survival, risk entirely drove survival, non-ideal selection correlated with survival but with additive risk effects, an ecological trap with maladaptive selection and a non-spatial effect of annual variation in weather. Indeed, we found positive relationships between the predicted values of a resource selection function (RSF) and survival, yet subsequently incorporating an additional negative effect of predation risk greatly improved models further. This revealed a positive, but non-ideal relationship between selection and survival. Gradients in these covariates were also shown to affect individual survival probability at multiple temporal scales. Exposure to increased predation risk had a relatively instantaneous effect on survival outcomes, whereas variation in habitat suitability predicted by an RSF had both instantaneous and longer-term seasonal effects on survival. Predation risk was an additive source of hazard beyond that detected through selection alone, and woodland caribou selection thus was shown to be non-ideal. Furthermore, by combining spatial adult female survival models with herd-specific estimates of recruitment in matrix population models, we estimated a spatially explicit landscape of population growth predictions for this endangered species.

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Habitat formation prevails over predation in influencing fouling communities.

Publications

Habitat formation prevails over predation in influencing fouling communities.

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