Fragment quality and sediment organic loading regulate the survival of an invasive, clonal seaweed

Bulleri, Fabio; Tamburello, Laura; Pusceddu, Antonio; Bonechi, Lisa; Cau, Alessandro; Moccia, Davide; Gribben, Paul E.

doi:10.1007/s10530-018-1685-4

Cited by 8 publications

(11 citation statements)

References 32 publications

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“…In accordance with the results of Bulleri et al. (), fragments without fronds consistently performed worst when compared to fragments with fronds (both intact and without rhizoids). This was somewhat surprising given that the rhizoids of other invasive Caulerpa spp.…”

Section: Discussionsupporting

confidence: 91%

“…), new rhizoids may be quickly generated without major consequences on final biomass and total stolon length (Bulleri et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…), can be re‐generated more rapidly compared to fronds and their loss has less impact on fragment establishment than frond loss (Bulleri et al. ). Thus, fragments lacking rhizoids may generally be of higher quality than fragments lacking fronds.…”

Section: Introductionmentioning

confidence: 99%

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Propagules are not all equal: traits of vegetative fragments and disturbance regulate invasion success

Uyà

Bulleri

Gribben

2018

Ecology

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Invasion success is regulated by multiple factors. While the roles of disturbance and propagule pressure in regulating the establishment of non-native species are widely acknowledged, that of propagule morphology (a proxy for quality) is poorly known. By means of a multi-factorial field experiment, we tested how the number (5 vs. 10) and quality (intact, without fronds or without rhizoids) of fragments of the clonal invasive seaweed, Caulerpa cylindracea, influenced its ability to establish in patches of the native seagrass, Posidonia oceanica, exposed to different intensities of disturbance (0, 50, or 100% reduction in canopy cover). We hypothesized that the ability of fragments to establish would be greater for intact fragments (high quality) and reduced more by frond removal (low quality) than rhizoid removal (intermediate quality). At low propagule pressure or quality, fragment establishment was predicted to increase with increasing disturbance, whereas, at high propagule pressure or quality, it was predicted to be high regardless of disturbance intensity. Disturbance intensity, fragment number and quality had independent effects on C. cylindracea establishment success. Disturbance always facilitated fragment establishment. However, fragments retaining fronds, either intact or deprived of rhizoids, had higher establishment success than fragments deprived of fronds. Increasing propagule number had weak effects on the cover of C. cylindracea. Our results demonstrate that propagule traits enabling the acquisition of resources made available by disturbance can be more important than propagule number in determining the establishment and spread of clonal non-native plants. More generally, our study suggests that propagule quality is a key, yet underexplored, determinant of invasion success.

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Section: Discussionsupporting

confidence: 91%

“…), new rhizoids may be quickly generated without major consequences on final biomass and total stolon length (Bulleri et al. ).…”

Section: Discussionmentioning

confidence: 99%

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Propagules are not all equal: traits of vegetative fragments and disturbance regulate invasion success

Uyà

Bulleri

Gribben

2018

Ecology

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“…Sediment anoxic conditions in the absence of seagrasses have been shown to facilitate establishment and growth in both C. taxifolia and C. cylindracea (Gribben et al, , ). These seaweeds can quickly regenerate rhizoids from both fronds and stolon fragments, suggesting that the lack of these structures does not impair establishment where abiotic conditions are suitable and resources freely available to allow for regeneration without a cost to other structures (Bulleri et al, ; Gribben et al, ; Smith & Walters, ; Uyà et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Although less explored, fragment characteristics underpinning establishment success of clonal plants are unlikely to be universal, but rather dependent upon the biotic and abiotic conditions of the recipient system. For example, fragments of the clonal seaweed, Caulerpa cylindracea , lacking rhizoids performed as well as intact fragments and better than fragments lacking fronds, but only when sediments were enriched in organic matter (Bulleri et al, ). Likewise, in the cogongrass, positive effects of increased fragment size on tiller production and growth were modulated by light levels (Estrada et al, ).…”

Section: Introductionmentioning

confidence: 99%

Propagule composition regulates the success of an invasive seaweed across a heterogeneous seascape

et al. 2019

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1. Propagule pressure is acknowledged as a key determinant of invasion success.Nonetheless, the role of morphological or physiological attributes of propagules (i.e. their quality) in regulating invader establishment has been little explored. In particular, no study has investigated how the presence of propagules differing in quality within an inoculum influences establishment across heterogeneous landscapes.2. We experimentally tested the hypothesis that the quality (+Fronds+Rhizoids; +Fronds−Rhizoids; −Fronds+Rhizoids) and the diversity (1, 2 and 3 fragment types) of vegetative fragments of the seaweed Caulerpa taxifolia determine their establishment success across seascapes consisting of bare sediments and patches of the seagrass Zostera muelleri exposed to different disturbance intensities (control, seagrass canopy clipping and total removal).3. After 6 weeks, seaweed biomass, stolon and frond length, frond and rhizoid number were generally greater in unvegetated habitats (bare sediments and total seagrass removal) than full or reduced seagrass canopies. The type and the diversity of types of fragments inoculated had significant effects on the final biomass and morphological features of C. taxifolia only in vegetated habitats. In control plots, inocula of fragments retaining both fronds and rhizoids achieved higher biomass, developed longer stolons and more fronds. In canopy clipping plots, mixed inocula of +Fronds+Rhizoids and −Fronds+Rhizoids fragments had the greatest biomass and stolon length. Synthesis.Assessing how propagules differing in quality perform in different habitats might be not sufficient to draw a comprehensive picture of invasion risk, as their establishment can be modulated by both negative and positive interactions among them. Propagule composition should be, therefore, considered as a further dimension of propagule pressure. Our results also suggest that the relevance of specific propagule traits for invader establishment decreases from intact to degraded habitats. Considering propagule size in terms of amount of competent propagules, rather than an absolute measure, would refine our ability of predicting invasion risk across habitats differing in biotic or abiotic conditions.

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The role of environmental conditions in regulating long-term dynamics of an invasive seaweed

et al. 2022

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The mechanisms underpinning long-term dynamics and viability of invader populations in the receiving environment remain largely unknown. We tested the hypothesis that temporal variations in the abundance of a well-established invasive seaweed, Caulerpa cylindracea, in the NW Mediterranean, could be regulated by inter-annual fluctuations in environmental conditions. Abundance data of C. cylindracea, sampled repeatedly between 2005 and 2020 at the peak of its growing season (late summer/early fall), were related to interannual variations in seasonal seawater temperature, wind speed and rainfall recorded during different growth phases of the alga, in both subtidal and intertidal habitats. In both habitats, higher peak of C. cylindracea cover was associated with lower seawater temperature in spring and summer, when the seaweed exits the winter resting phase and starts a period of active growth. In addition, the peak abundance of subtidal C. cylindracea was positively associated with higher autumn wind speed intensity and spring daily total precipitation. Our study reveals the importance of seasonal and interannual variation of abiotic factors in shaping temporal patterns of abundance of C. cylindracea, in both subtidal and intertidal habitats. Identifying the factors underpinning invasive population temporal dynamics and viability is essential to predict the time and conditions under which an invader can thrive, and thus guide management strategies aimed to containing invasions under current and future climates.

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Fragment quality and sediment organic loading regulate the survival of an invasive, clonal seaweed

Cited by 8 publications

References 32 publications

Propagules are not all equal: traits of vegetative fragments and disturbance regulate invasion success

Propagules are not all equal: traits of vegetative fragments and disturbance regulate invasion success

Propagule composition regulates the success of an invasive seaweed across a heterogeneous seascape

The role of environmental conditions in regulating long-term dynamics of an invasive seaweed

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