Establishment of the introduced kelp Undaria pinnatifida following dieback of the native macroalga Phyllospora comosa in Tasmania, Australia

Valentine, Joseph P.; Johnson, Craig R.

doi:10.1071/mf03048

Cited by 80 publications

(39 citation statements)

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“…Control denotes plots that were physically disturbed but did not receive detritus. Circles enclose groups of treatments that were statistically indistinguishable (at a = 0.05), according to PERMANOVA analysis, n = 7 competition with the introduced macroalga Undaria pinnatifida is limiting the ability of P. comosa to reestablish following natural die-back (Valentine and Johnson 2004). Such declines in this important habitat-forming alga may therefore have widespread consequences, extending to changes in soft-sediment systems.…”

Section: Snk Testmentioning

confidence: 98%

Cross-habitat impacts of species decline: response of estuarine sediment communities to changing detrital resources

2010

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Food webs of many ecosystems are sustained by organic matter from other habitats. Human activities and climatic change are increasingly modifying the quality and supply of these resources, yet for most ecosystems it is unknown how the taxonomic composition of organic matter influences community composition. Along the coastline of Sydney, Australia, the once abundant habitat-forming macroalga, Phyllospora comosa, is now locally extinct. Shallow reefs are now primarily occupied by Sargassum sp. and, to a lesser extent, the kelp Ecklonia radiata. We experimentally manipulated the supply of P. comosa, Sargassum sp. and E. radiata to estuarine sediments to assess responses by macroinvertebrate communities to: (1) changing the identity of the dominant detrital resource; and (2) varying the ratio of input of different macrophytes. Estuarine sediments dosed with P. comosa supported greater abundances of macroinvertebrates than sediments receiving Sargassum sp. or the kelp E. radiata. Whereas plots receiving Sargassum sp. or E. radiata had fewer macroinvertebrates than controls, plots receiving a moderate (120 g dry weight per m(2)) loading of P. comosa had more. Mixtures of detritus dominated by P. comosa supported similar macroinvertebrate communities to monocultures of the alga. Communities in sediments receiving detritus comprised of less than one-third P. comosa were, however, distinctly different. Our study provides evidence that the ecological ramifications of species decline can extend to spatially removed ecosystems, subsidized by allochthonous materials. Even prior to extinction of detrital sources, small changes in their provision of organic matter may alter the structure of subsidized communities.

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Section: Snk Testmentioning

confidence: 98%

Cross-habitat impacts of species decline: response of estuarine sediment communities to changing detrital resources

2010

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“…At this stage of invasion, competitive effects through canopy shading, pre-emption of primary substratum and overgrowth may compromise the ability of an invader to establish viable populations (Britton-Simmons 2006, Scheibling & Gagnon 2006, Dunstan & Johnson 2007, Valentine et al 2007, Thomsen et al 2009). Conversely, disturbances that create gaps in natural communities may allow invasion (Valentine & Johnson 2003, Edgar et al 2004, Valentine & Johnson 2004, Incera et al 2010, and particular types of benthic cover may actually facilitate invasion (Bulleri & BenedettiCecchi 2008, Bulleri et al 2009, Bulleri et al 2011. Unfortunately, in terms of management and in-depth understanding of processes, many of them are context-dependent (Thomsen et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Subtidally, the presence of a dense native algal canopy has been shown to inhibit the invasion of marine alien species due to prior space occupancy and/or lack of resource availability (e.g. light), with successful invasion occurring only following native canopy removal (Valentine & Johnson 2003, Edgar et al 2004, Valentine & Johnson 2004, Scheibling & Gagnon 2006, Valentine et al 2007, Bulleri et al 2010. The timing of gap creation or disturbance is also important, with maximum recruitment of the invader occurring when the disturbance was just prior to its reproduction season (Valentine & Johnson 2003, Incera et al 2010, Airoldi & Bulleri 2011.…”

Section: Introductionmentioning

confidence: 99%

“…In marine algal assemblages, these involve a combination of life-history traits of an invader, the characteristics of native communities, and ecological processes such as disturbance, competition and facilitation (Valentine & Johnson 2003, Edgar et al 2004, Valentine & Johnson 2004, Britton-Simmons & Abbott 2008, Mineur et al 2008, Thomsen et al 2009). The growing number of successful invasions worldwide is testament to the numerous life-history traits and mechanisms that allow invaders to establish successfully (Valentine et al 2007, Engelen & Santos 2009).…”

Section: Introductionmentioning

confidence: 99%

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Resistance and facilitation by native algal communities in the invasion success of Undaria pinnatifida

Thompson¹,

Schiel²

2012

Mar. Ecol. Prog. Ser.

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ABSTRACT:The mechanisms by which non-indigenous species overcome resistance in native communities are not well understood but are fundamental to the ability of invaders to persist and spread once they reach alien shores. One of the most widespread invaders is the kelp Undaria pinnatifida. Here we test disturbance, competition and facilitation in its recruitment into intertidal algal communities in southern New Zealand. In field-based experiments, we manipulated native fucoid and U. pinnatifida canopies, as well as the abundance and type of understory turfing species, and provided various gap sizes in native communities. Undaria pinnatifida recruitment occurred almost exclusively on coralline turf and in the absence of canopies, both native and conspecific. Where the native fucoid canopy was removed, U. pinnatifida recruited into gaps of all sizes (5 × 5 cm, 25 × 25 cm, 50 × 50 cm), but the smallest gaps recovered their native canopy within several months and precluded further recruitment. Experimental manipulations of coralline turf showed that recruitment of U. pinnatifida was orders of magnitude greater where turf was present, regardless of the timing or sizes of clearances. Facilitation did not occur with other turfing species. Overall, native fucoids showed high resistance to invasion, but there was great facilitation by native coralline turf. Furthermore, as annual U. pinnatifida canopies disappear over summer, it is clear that coralline turf harbors the microscopic stages of U. pinnatifida that will form the following year's populations. As turfing species increase and persist following disturbances of native canopies worldwide, it can be expected that the recruitment dynamics of non-indigenous species will also change.

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“…Sargassum, Coleman et al 2008a) that have increased in abundance where Phyllospora has been lost. Indeed, recolonisation of Phyllospora has been shown to be inhibited by the pre-emptive 68 Coleman & Kelaher: Connectivity among fragmented populations of macroalgae establishment of other species in Tasmania (Valentine & Johnson 2004). Natural recolonisation in Sydney may, therefore, require intervention or the occurrence of ecological processes that free up space currently occupied by algal turfs (e.g.…”

mentioning

confidence: 99%

Connectivity among fragmented populations of a habitat-forming alga, Phyllospora comosa (Phaeophyceae, Fucales) on an urbanised coast

Coleman¹,

Kelaher²

2009

Mar. Ecol. Prog. Ser.

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Despite a growing body of knowledge on the ecological consequences of loss and fragmentation of habitat-forming macroalgae, little is known about the genetic implications of such losses. Here, we investigate the genetic consequences of fragmentation caused by the loss of the habitat-forming macroalga Phyllospora comosa from 70 km of urbanised coastline in Sydney, Australia. Contrary to predictions, there appeared to be substantial connectivity among fragmented populations, although spatial autocorrelation analysis revealed that this may be an artifact of allele size homoplasy beyond scales of ~80 km. Genetic differentiation was not related to geographic separation of populations. This may be explained by the nature of prevailing currents (East Australian Current) that promote nonlinear dispersal in 'leaps', sourcing propagules from one area and depositing them via eddies that either come ashore or disperse. Populations that were tens of kilometers apart were often genetically different, which was likely due to barriers to dispersal, such as sandy beaches and mouths of estuaries, or rapid fertilization and recruitment of zygotes on small spatial scales. Our research provides a basis for designing a rehabilitation program for populations of Phyllospora comosa, with appropriate consideration of genetic diversity and structure.KEY WORDS: Microsatellites · Fucoid · Phyllospora comosa · Algae · Dispersal · Connectivity · Decline Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 381: [63][64][65][66][67][68][69][70] 2009 Frankham 1998, Saccheri et al. 1998, Tanaka 2000, Keller & Waller 2002. It is critical, therefore, to understand levels of connectivity among fragmented populations of habitat-forming macroalgae to help elucidate the processes responsible for precipitating losses in the first place. This may also help in the accurate prediction of whether natural recolonisation or recovery of populations is likely to occur, and therefore aid in the design and implementation of rehabilitation programs.The monotypic Phyllospora comosa (Labillardière) C. Agardh, hereafter referred to as Phyllospora, is an important habitat-forming macroalga on shallow subtidal reefs (0 to 5 m depth) in eastern Australia, where it often accounts for 100% of canopy cover (Coleman et al. 2008a). Along the coast of New South Wales (NSW), populations of this perennial, dioecious fucoid alga have approximately equal ratios of male and female individuals (M. A. Coleman unpubl. data), and reproduce throughout the year (M. A. Coleman pers. obs.) via release of sperm and external fertilisation of eggs that remain attached to the female thallus. Since the 1940s, Phyllospora has disappeared from urbanised coastlines around Sydney, leaving a 70 km gap in its distribution (Coleman et al. 2008a). Indeed, a recent comprehensive SCUBA, snorkel and literature survey did not find a single individual growing along 70 km of Sydney reefs, despite being common half a century ago (Coleman et al. 2008a). ...

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Establishment of the introduced kelp Undaria pinnatifida following dieback of the native macroalga Phyllospora comosa in Tasmania, Australia

Cited by 80 publications

References 36 publications

Cross-habitat impacts of species decline: response of estuarine sediment communities to changing detrital resources

Cross-habitat impacts of species decline: response of estuarine sediment communities to changing detrital resources

Resistance and facilitation by native algal communities in the invasion success of Undaria pinnatifida

Connectivity among fragmented populations of a habitat-forming alga, Phyllospora comosa (Phaeophyceae, Fucales) on an urbanised coast

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