Paul Gribben

Microbial communities in marine sediments modify success of an invasive macrophyte

Publisher: Springer Science and Business Media LLC

Date: 29-08-2017

DOI: 10.1038/S41598-017-10231-2

Abstract: Invasive plants have extensive impacts on ecosystem function and bio ersity globally. Our inability to manage invasive species stems in part from a lack of understanding of the processes that control their successful establishment and spread. To date, studies have largely considered how above-ground processes control native/invasive plant interactions. Emerging research from terrestrial and wetland ecosystems demonstrates that below-ground processes under microbial control can determine the outcome of interactions between native and invasive plants. Whether sediment microbes modify the success of invasive macrophytes in marine ecosystems is untested, despite marine sediment microbes controlling many ecological processes (e.g. nutrient cycling) comparable to those in terrestrial ecosystems. We first show that sediment bacterial communities differ between the native seagrass Zostera capricorni and the invasive alga Caulerpa taxifolia and that those differences relate to functional changes in sulfur cycling between the macrophytes. Second, by experimentally manipulating the microbial communities we show that intact microbial communities in Z . capricorni sediments provide biotic resistance by reducing C . taxifolia fragment growth 119% compared to when they are inactive, and intact microbial communities in C . taxifolia sediments have positive feedbacks by increasing fragment growth 200%. Thus, similar to terrestrial ecosystems, microorganisms appear to indirectly control the success of invasive macrophytes in marine ecosystems.

Facilitation cascades create a predation refuge for biodiversity in a novel connected habitat

Publisher: Wiley

Date: 04-2020

DOI: 10.1002/ECS2.3053

Linking habitat interactions and biodiversity within seascapes

Publisher: Wiley

Date: 04-2022

DOI: 10.1002/ECS2.4021

Abstract: Habitat interactions play key roles in regulating bio ersity and ecosystem functions. This is particularly important in aquatic ecosystems, where the flow of water facilitates exchanges of energy and matter. Oyster reefs, a highly degraded habitat globally and a key focus for restoration efforts, can reduce water movement and facilitate the deposition of particles around them, affecting nutrient cycling in surrounding sediments. The effects of these reefs on sediment infauna taxonomic and functional bio ersity, however, remain unknown. We s led sediments at increasing distances from reefs at three estuaries to evaluate the relationships between proximity to oyster reefs and composition and functionality of infaunal communities and explored the potential mechanisms behind those relationships. Sediments close to oyster reefs had consistently greater amounts of labile organic matter, which in turn was positively related to the number of taxa and total abundance of infauna. Also, the functional traits of infauna, such as bioturbation and feeding modes, were related to proximity to reefs, but they were variable between estuaries indicating the importance of background estuarine environmental conditions. These results suggest that habitat linkages between oyster reefs and sediments are important in regulating taxonomic bio ersity, while functional bio ersity seems to be driven by processes operating at larger scales. Given burgeoning restoration initiatives worldwide, particularly those of oyster reefs, incorporating seascape interactions can help inform recovery of bio ersity and functions beyond the target habitat at the seascape level, which is often overlooked.

Reduced performance of native infauna following recruitment to a habitat-forming invasive marine alga

Publisher: Springer Science and Business Media LLC

Date: 22-10-2008

DOI: 10.1007/S00442-008-1181-0

Abstract: Despite well-documented negative impacts of invasive species on native biota, evidence for the facilitation of native organisms, particularly by habitat-forming invasive species, is increasing. However, most of these studies are conducted at the population or community level, and we know little about the in idual fitness consequences of recruitment to habitat-forming invasive species and, consequently, whether recruitment to these habitats is adaptive. We determined the consequences of recruitment to the invasive green alga Caulerpa taxifolia on the native soft-sediment bivalve Anadara trapezia and nearby unvegetated sediment. Initially, we documented the growth and survivorship of A. trapezia following a natural recruitment event, to which recruitment to C. taxifolia was very high. After 12 months, few clams remained in either habitat, and those that remained showed little growth. Experimental manipulations of recruits demonstrated that all performance measures (survivorship, growth and condition) were significantly reduced in C. taxifolia sediments compared to unvegetated sediments. Exploration of potential mechanisms responsible for the reduced performance in C. taxifolia sediments showed that water flow and water column dissolved oxygen (DO) were significantly reduced under the canopy of C. taxifolia and that sediment anoxia was significantly higher and sediment sulphides greater in C. taxifolia sediments. However, phytoplankton abundance (an indicator of food supply) was significantly higher in C. taxifolia sediments than in unvegetated ones. Our results demonstrate that recruitment of native species to habitat-forming invasive species can reduce growth, condition and survivorship and that studies conducted at the community level may lead to erroneous conclusions about the impacts of invaders and should include studies on life-history traits, particularly juveniles.

Invasion expansion

Publisher: Springer Science and Business Media LLC

Date: 31-07-2015

DOI: 10.1038/SREP12436

Abstract: Strategies for managing biological invasions are often based on the premise that characteristics of invading species and the invaded environment are key predictors of the invader’s distribution. Yet, for either biological traits or environmental characteristics to explain distribution, adequate time must have elapsed for species to spread to all potential habitats. We compiled and analyzed a database of natural history and ecological traits of 138 coastal marine invertebrate species, the environmental conditions at sites to which they have been introduced and their date of first introduction. We found that time since introduction explained the largest fraction (20%) of the variability in non-native range size, while traits of the species and environmental variables had significant, but minimal, influence on non-native range size. The positive relationship between time since introduction and range size indicates that non-native marine invertebrate species are not at equilibrium and are still spreading, posing a major challenge for management of coastal ecosystems.

Beyond the border: Effects of an expanding algal habitat on the fauna of neighbouring habitats

Publisher: Elsevier BV

Date: 05-2015

DOI: 10.1016/J.MARENVRES.2015.02.006

Abstract: The impacts of novel habitat-forming organisms on associated fauna have been difficult to predict, and may affect the fauna of neighbouring habitats due to changes in the spatial configuration of habitat patches of differing quality. Here, we test whether the localised expansion of a native habitat-forming macroalga, Caulerpa filiformis, on subtidal reefs can affect the abundance of fauna associated with a neighbouring macroalgal habitat. C. filiformis was a functionally distinct habitat for fauna, and the total abundance of epifauna associated with the resident alga, Sargassum linearifolium, was reduced at some sites when in close proximity to or surrounded by C. filiformis. Experimental manipulation of habitat configuration demonstrated that the low abundance of gastropods on S. linearifolium when surrounded by C. filiformis was likely explained by C. filiformis acting as a physical dispersal barrier for mobile fauna. Changes to the spatial configuration of novel and resident habitats can thus affect the abundance of fauna in addition to the direct replacement of habitats by species undergoing range expansions or increasing in abundance.

Trait and abundance patterns in two marine molluscs: the influence of abiotic conditions operating across multiple spatial scales

Publisher: Inter-Research Science Center

Date: 30-08-2012

DOI: 10.3354/MEPS09847

Biogeographic comparisons of the traits and abundance of an invasive crab throughout its native and invasive ranges

Publisher: Springer Science and Business Media LLC

Date: 22-01-2013

DOI: 10.1007/S10530-013-0416-0

Carry over effects of nutrient addition on the recovery of an invasive seaweed from the winter die-back

Publisher: Elsevier BV

Date: 05-2017

DOI: 10.1016/J.MARENVRES.2017.02.006

Abstract: Nutrient enrichment of coastal waters can enhance the invasibility and regrowth of non-native species. The invasive alga Caulerpa cylindracea has two distinct phases: a well-studied fast-growing summer phase, and a winter latent phase. To investigate the effects of nutrient enrichment on the regrowth of the seaweed after the winter resting-phase, a manipulative experiment was carried out in intertidal rockpools in the North-western Mediterranean. Nutrients were supplied under different temporal regimes: press (constant release from January to May), winter pulse (January to March) and spring pulse (March to May). Independently from the temporal characteristics of their addition, nutrients accelerated the re-growth of C. cylindracea after the winter die-back, resulting in increased percentage covers at the peak of the growing season. Nutrient addition did not influence the number and length of fronds and the biomass. Native components of the algal community did not respond to nutrient additions. Our results show that nutrient supply can favour the spread of C. cylindracea even when occurring at a time of the year at which the seaweed is not actively growing.

Morphological traits and density of foundation species modulate a facilitation cascade in Australian mangroves

Publisher: Wiley

Date: 09-2013

DOI: 10.1890/12-1847.1

Abstract: Facilitation cascades are critical to the maintenance of bio ersity in a variety of habitats. Through a series of two experiments, we examined how the morphological traits and density of interacting foundation species influence the establishment and persistence of a facilitation cascade in temperate Australian mangrove forests. In this system, mangrove pneumatophores trap the free-living alga, Hormosira banksii, which, in turn, supports dense and erse assemblages of epifaunal mollusks. The first experiment, which manipulated pneumatophore height and density, revealed that these two traits each had additive negative effects on the establishment, but additive positive effects on the persistence of the cascade. High densities of tall pneumatophores initially served as a physical barrier to algal colonization of pneumatophore plots, but over the longer-term enhanced the retention of algae. The increased algal biomass, in turn, facilitating epifaunal colonization. The second experiment demonstrated that the retention of algae by pneumatophores was influenced more by algal thallus length than vesicle diameter, and this effect occurred independent of pneumatophore height. Our study has extended facilitation theory by showing that the morphological traits and density of basal and intermediary facilitators influence both the establishment and persistence of facilitation cascades. Hence, attempts to use foundation species as a tool for restoration will require an understanding not only of the interactions among these, but also of the key traits that modify interrelationships.

Habitat variability in an underwater forest: Using a trait‐based approach to predict associated communities

Publisher: Wiley

Date: 30-01-2020

DOI: 10.1111/1365-2435.13523

Impact of cigarette butt leachate on tidepool snails

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.MARPOLBUL.2015.04.004

Abstract: In urban areas, cigarette butts are the most common discarded refuse articles. In marine intertidal zones, they often fall into tidepools. We tested how common intertidal molluscs were affected by butt leachate in a laboratory experiment, where snails were exposed to various leachate concentrations. Mortality was very high, with all species showing 100% mortality at the full leachate concentration (5 butts per litre and 2h soak time) after 8days. However, Austrocochlea porcata showed higher mortality than the other 2 species at lower concentrations (10%, 25%) which may affect the relative abundance of the 3 snails under different concentrations of leachate pollution. Also, sublethal effects of leachate on snail activity were observed, with greater activity of Nerita atramentosa than the other 2 species at higher concentrations, suggesting it is more resilient than the other 2 species. While human health concerns predominate with respect to smoking, we show strong lethal and sublethal (via behavioural modifications) impacts of discarded butts on intertidal organisms, with even closely-related taxa responding differently.

Sydney Harbour: What we do and do not know about a highly diverse estuary

Publisher: CSIRO Publishing

Date: 2015

DOI: 10.1071/MF15159

Abstract: Sydney Harbour is a global hotspot for marine and estuarine ersity. Despite its social, economic and biological value, the available knowledge has not previously been reviewed or synthesised. We systematically reviewed the published literature and consulted experts to establish our current understanding of the Harbour’s natural systems, identify knowledge gaps, and compare Sydney Harbour to other major estuaries worldwide. Of the 110 studies in our review, 81 focussed on ecology or biology, six on the chemistry, 10 on geology and 11 on oceanography. Subtidal rocky reef habitats were the most studied, with a focus on habitat forming macroalgae. In total 586 fish species have been recorded from the Harbour, which is high relative to other major estuaries worldwide. There has been a lack of process studies, and an almost complete absence of substantial time series that constrains our capacity to identify trends, environmental thresholds or major drivers of biotic interactions. We also highlight a lack of knowledge on the ecological functioning of Sydney Harbour, including studies on microbial communities. A sound understanding of the complexity, connectivity and dynamics underlying ecosystem functioning will allow further advances in management for the Harbour and for similarly modified estuaries around the world.

Personality and plasticity: Consistent responses within-, but not across-temperature situations in crabs

Publisher: Brill

Date: 2013

DOI: 10.1163/1568539X-00003081

Surface chemistry versus whole-cell extracts: antifouling tests with seaweed metabolites

Publisher: Inter-Research Science Center

Date: 11-01-2007

DOI: 10.3354/MEPS329073

The influence of oyster reefs and surrounding sediments on nitrogen removal - an insitu study along the East coast of Australia

Publisher: Elsevier BV

Date: 11-2023

DOI: 10.1016/J.ENVRES.2023.116947

Experimental evidence root‐associated microbes mediate seagrass response to environmental stress

Publisher: Wiley

Date: 13-02-2023

DOI: 10.1111/1365-2745.14081

Abstract: Below‐ground microbiota play an important role in mediating environmental conditions with important consequences for plant performance. Micro‐organisms involved in plant–soil interactions may be associated with roots or bulk soil however, the relative influence of these below‐ground microbial assemblages on plant performance is poorly known, particularly for marine plants. We separately manipulated the root and sediment microbial assemblages of the seagrass Zostera muelleri in a fully factorial experiment to determine how these assemblages determined plant response (e.g. growth) to nutrient enrichment, a major stressor in marine systems. Under ambient nutrient conditions, seagrass growth was maintained regardless of root microbial assemblage disruption. Under high nutrient stress, however, seagrasses with disrupted root microbiota had reduced growth, whereas growth was maintained in seagrasses with an intact root microbiota. Disruption of bulk‐sediment microbiota did not affect seagrass growth. Nutrient elevation was correlated with enhanced abundances of several putatively beneficial microbial taxa (e.g. sulphide‐oxidising Beggiatoaceae and denitrifying Geofilum rubicundum ) associated with roots. Synthesis . Our results suggest that under ambient nutrient conditions micro‐organisms play a reduced role in influencing plant performance, but under more stressful conditions positive plant–root micro‐organism interactions strengthened. These results are among the first to experimentally determine that interactions between marine plants and the root‐associated microbiota are key drivers of seagrass performance under human‐induced environmental changes. This suggests that as in terrestrial systems, marine plant resilience depends on the stress‐mitigating functions of their root‐associated microbiota and disturbance to those plant–microbiota interactions can be deleterious for plant performance. Improving our understanding of these plant–micro‐organism interactions may be critical for understanding the functioning and resilience of threatened marine plants and developing more effective restoration strategies for them.

Additive and site-specific effects of two foundation species on invertebrate community structure

Publisher: Inter-Research Science Center

Date: 04-08-2014

DOI: 10.3354/MEPS10867

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

Publisher: Wiley

Date: 18-11-2019

DOI: 10.1111/1365-2745.13313

Growth rates of the venus clam Ruditapes largillierti grown under experimental culture conditions in New Zealand

Publisher: Elsevier BV

Date: 10-2002

DOI: 10.1016/S0044-8486(02)00028-5

Habitat provided by native species facilitates higher abundances of an invader in its introduced compared to native range

Publisher: Springer Science and Business Media LLC

Date: 14-04-2020

DOI: 10.1038/S41598-020-63429-2

Abstract: The impacts invasive species have on bio ersity and ecosystem function globally have been linked to the higher abundances they often obtain in their introduced compared to native ranges. Higher abundances of invaders in the introduced range are often explained by a reduction in negative species interactions in that range, although results are equivocal. The role of positive interactions in explaining differences in the abundance of invaders between native and invasive ranges has not been tested. Using biogeographic surveys, we showed that the rocky shore porcelain crab, Petrolisthes elongatus , was ~4 times more abundant in its introduced (Tasmania, Australia) compared to its native (New Zealand) range. The habitat of these crabs in the invaded range (underside of intertidal boulders) was extensively covered with the habitat-forming tubeworm Galeolaria caespitosa . We tested whether the habitat provided by the tubeworm facilitates a higher abundance of the invasive crab by creating mimics of boulders with and without the tubeworm physical structure and measured crab colonisation into these habitats at three sites in both Tasmania and New Zealand. Adding the tubeworm structure increased crab abundance by an average of 85% across all sites in both ranges. Our intercontinental biogeographic survey and experiment demonstrate that native species can facilitate invader abundance and that positive interactions can be important drivers of invasion success.

Sydney Harbour: A review of anthropogenic impacts on the biodiversity and ecosystem function of one of the world's largest natural harbours

Publisher: CSIRO Publishing

Date: 2015

DOI: 10.1071/MF15157

Abstract: Sydney Harbour is a hotspot for ersity. However, as with estuaries worldwide, its ersity and functioning faces increasing threats from urbanisation. This is the first synthesis of threats and impacts in Sydney Harbour. In total 200 studies were reviewed: 109 focussed on contamination, 58 on habitat modification, 11 addressed non-indigenous species (NIS) and eight investigated fisheries. Metal concentrations in sediments and seaweeds are among the highest recorded worldwide and organic contamination can also be high. Contamination is associated with increased abundances of opportunistic species, and changes in benthic community structure. The Harbour is also heavily invaded, but invaders’ ecological and economic impacts are poorly quantified. Communities within Sydney Harbour are significantly affected by extensive physical modification, with artificial structures supporting more NIS and lower ersity than their natural equivalents. We know little about the effects of fishing on the Harbour’s ecology, and although ocean warming along Sydney is among the fastest in the world, we know little about how the ecosystem will respond to warming. The interactive and cumulative effects of stressors on ecosystem functioning and services in the Harbour are largely unknown. Sustainable management of this iconic natural system requires that knowledge gaps are addressed and translated into coherent environmental plans.

Publisher Correction: Heterogeneity within and among co-occurring foundation species increases biodiversity

Publisher: Springer Science and Business Media LLC

Date: 28-03-2022

DOI: 10.1038/S41467-022-29347-9

Larval settlement preference of a native bivalve: the influence of an invasive alga versus native substrata

Publisher: Inter-Research Science Center

Date: 05-11-2009

DOI: 10.3354/AB00196

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

Publisher: Wiley

Date: 25-03-2018

DOI: 10.1002/ECY.2168

Abstract: 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.

Facilitation of an invader by a native habitat‐former increases along interacting gradients of environmental stress

Publisher: Wiley

Date: 11-03-2020

DOI: 10.1002/ECY.2961

Abstract: Native habitat-forming species can facilitate invasion by reducing environmental stress or consumer pressure. However, the intensity of one stressor along a local gradient may differ when expanding the scale of observation to encompass major variations in background environmental conditions. In this study, we determined how facilitation of the invasive porcelain crab, Petrolisthes elongatus, by the native tube-forming serpulid, Galeolaria caespitosa, varied with environmental gradients at local (tidal height) and larger (wave exposure) spatial scales. G. caespitosa constructs a complex calcareous matrix on the underside of intertidal boulders and we predicted that its positive effects on P. elongatus density would increase in intensity with shore height and be stronger at wave-sheltered than wave-exposed locations. To test these predictions, we conducted two experiments. First, we determined the effects of serpulid presence (boulders with live or dead serpulid matrix vs. bare boulders) at six shore heights that covered the intertidal distribution of P. elongatus. Second, we determined the effects of serpulid presence (present vs. absent), shore height (high vs. low) and wave exposure (sheltered vs. exposed) on crabs across six locations within the invaded range in northern Tasmania, Australia. In Experiment 1, the presence of serpulids (either dead or alive) enhanced P. elongatus densities at all shore heights, with facilitation intensity (as determined by a relative interaction index RII) tending to increase with shore height. In Experiment 2, serpulids facilitated P. elongatus across shore heights and wave exposures, although crab densities were lower at high shore levels of wave-sheltered locations. However, the intensity of crab facilitation by serpulids was greater on wave-sheltered than on wave-exposed shores, but only at the high shore level. This study demonstrates that local effects of native habitat-formers on invasive species are dependent on prevailing environmental conditions at larger spatial scales and that, under more stressful conditions, invaders become increasingly reliant on positive interactions with native habitat-formers. Increased strength of local-scale facilitation by native species, d ening broader scale variations in environmental stressors, could enhance the ability of invasive species to establish self-sustaining populations in the invaded range.

Body size affects lethal and sublethal responses to organic enrichment: Evidence of associational susceptibility for an infaunal bivalve

Publisher: Elsevier BV

Date: 07-2021

DOI: 10.1016/J.MARENVRES.2021.105391

Specific niche requirements underpin multidecadal range edge stability, but may introduce barriers for climate change adaptation

Publisher: Wiley

Date: 02-02-2021

DOI: 10.1111/DDI.13224

Abstract: To investigate some of the environmental variables underpinning the past and present distribution of an ecosystem engineer near its poleward range edge. locations spanning ,400 km around Ireland. We collated past and present distribution records on a known climate change indicator, the reef‐forming worm Sabellaria alveolata (Linnaeus, 1767) in a biogeographic boundary region over 182 years (1836–2018). This included repeat s ling of 60 locations in the cooler 1950s and again in the warmer 2000s and 2010s. Using species distribution modelling, we identified some of the environmental drivers that likely underpin S. alveolata distribution towards the leading edge of its biogeographical range in Ireland. Through plotting 981 records of presence and absence, we revealed a discontinuous distribution with discretely bounded sub‐populations, and edges that coincide with the locations of tidal fronts. Repeat surveys of 60 locations across three time periods showed evidence of population increases, declines, local extirpation and recolonization events within the range, but no evidence of extensions beyond the previously identified distribution limits, despite decades of warming. At a regional scale, populations were relatively stable through time, but local populations in the cold Irish Sea appear highly dynamic and vulnerable to local extirpation risk. Contemporary distribution data (2013–2018) computed with modelled environmental data identified specific niche requirements which can explain the many distribution gaps, namely wave height, tidal litude, stratification index, then substrate type. In the face of climate warming, such specific niche requirements can create environmental barriers that may prevent species from extending beyond their leading edges. These boundaries may limit a species’ capacity to redistribute in response to global environmental change.

Observation of juvenile Eastern Blue Groper (Achoerodus viridis) on remnant oyster reefs in New South Wales, Australia.

Publisher: Wiley

Date: 22-09-2022

DOI: 10.1002/ECY.3824

Positive and negative interactions control a facilitation cascade

Publisher: Wiley

Date: 12-2017

DOI: 10.1002/ECS2.2065

Impacts of a non-native gastropod with a limited distribution; less conspicuous invaders matter too

Publisher: Inter-Research Science Center

Date: 14-10-0010

DOI: 10.3354/MEPS11469

Protandry in the New Zealand geoduck,Panopea zelandica(Mollusca, Bivalvia)

Publisher: Informa UK Limited

Date: 09-2003

DOI: 10.1080/07924259.2003.9652562

Non-natives: 141 scientists object

Publisher: Springer Science and Business Media LLC

Date: 07-2011

DOI: 10.1038/475036A

Shifts in biomass and structure of habitat‐formers across a latitudinal gradient

Publisher: Wiley

Date: 27-05-2021

DOI: 10.1002/ECE3.7714

Abstract: Global patterns of plant biomass drive the distribution of much of the marine and terrestrial life on Earth. This is because their biomass and physical structure have important consequences for the communities they support by providing food and habitat. In terrestrial ecosystems, temperature is one of the major determinants of plant biomass and can influence plant and leaf morphology. In temperate marine systems, macroalgae are major habitat‐formers and commonly display highly variable morphology in response to local environmental conditions. Variation in their morphology, and thus habitat structure on temperate reefs, however, is poorly understood across large scales. In this study, we used a trait‐based approach to quantify morphological variability in subtidal rocky reefs dominated by the algal genus Sargassum along a latitudinal gradient, in southeastern Australia (~900 km). We tested whether large‐scale variation in sea surface temperature (SST), site exposure, and nutrient availability can predict algal biomass and in idual morphology. We found Sargassum biomass declined with increasing maximum SST. We also found that in idual morphology varied with abiotic ocean variables. Frond size and intrain idual variability in frond size decreased with increasing with distance from the equator, as SST decreased and nitrate concentration increased. The shape of fronds displayed no clear relationship with any of the abiotic variables measured. These results suggest climate change will cause significant changes to the structure of Sargassum habitats along the southeastern coast of Australia, resulting in an overall reduction in biomass and increase in the prevalence of thalli with large, highly variable fronds. Using a space‐for‐time approach means shifts in morphological trait values can be used as early warning signs of impending species declines and regime shifts. Consequently, by studying traits and how they change across large scales we can potentially predict and anticipate the impacts of environmental change on these communities.

Sublethal effects of a rapidly spreading native alga on a key herbivore

Publisher: Wiley

Date: 16-08-2021

DOI: 10.1002/ECE3.8005

Abstract: Multiple anthropogenic stressors are causing a global decline in foundation species, including macrophytes, often resulting in the expansion of functionally different, more stressor‐tolerant macrophytes. Previously subdominant species may experience further positive demographic feedback if they are exposed to weaker plant–herbivore interactions, possibly via decreased palatability or being structurally different from the species they are replacing. However, the consequences of the spread of opportunistic macrophytes for the local distribution and life history of herbivores are unknown. The green alga, Caulerpa filiformis , previously a subdominant macrophyte on low intertidal‐shallow subtidal rock shores, is becoming locally more abundant and has spread into warmer waters across the coast of New South Wales, Australia. In this study, we measured (a) the distribution and abundance of a key consumer, the sea urchin Heliocidaris erythrogramma, across a seascape at sites where C. filiformis has become dominant, (b) performed behavioral field experiments to test the role of habitat selection in determining the local distribution of H. erythrogramma, and (c) consumer experiments to test differential palatability between previously dominant higher quality species like Ecklonia radiata and Sargassum sp. and C. filiformis and the physiological consequences of consuming it. At all sites, urchin densities were positively correlated with distance away from C. filiformis beds, and they actively moved away from beds. Feeding experiments showed that, while urchins consumed C. filiformis, sometimes in equal amounts to higher quality algae, there were strong sublethal consequences associated with C. filiformis consumption, mainly on reproductive potential (gonad size). Specifically, the gonad size of urchins that fed on C. filiformis was equivalent to that in starved urchins. There was also a tendency for urchin mortality to be greater when fed C. filiformis . Overall, strong negative effects on herbivore life‐history traits and potentially their survivorship may establish further positive feedback on C. filiformis abundance that contributes to its spread and may mediate shifts from top‐down to bottom‐up control at locations where C. filiformis has become dominant.

Differences in soft-sediment macrobenthic assemblages invaded by Caulerpa taxifolia compared to uninvaded habitats

Publisher: Inter-Research Science Center

Date: 07-04-2009

DOI: 10.3354/MEPS07926

Fine-scale responses of mobile invertebrates and mesopredatory fish to habitat configuration

Publisher: Elsevier BV

Date: 06-2021

DOI: 10.1016/J.MARENVRES.2021.105319

Unusual but consistent latitudinal patterns in macroalgal habitats and their invertebrate communities across two countries

Publisher: Wiley

Date: 29-05-2020

DOI: 10.1111/DDI.13070

Density-dependent facilitation cascades determine epifaunal community structure in temperate Australian mangroves

Publisher: Wiley

Date: 06-2012

DOI: 10.1890/10-2296.1

Abstract: Co-occurring foundation species can determine biological community structure via facilitation cascades. We examined the density dependencies of facilitation cascades, including how the density of a basal foundation species influences the density of secondary foundation species, and how the density of secondary foundation species influences community structure. The system in which we assessed density dependencies was a temperate mangrove forest in which pneumatophores trap the fucoid alga Hormosira banksii and provide substrate for the oyster, Saccostrea glomerata. The alga and oyster in turn determine benthic community structure. In the field, algal biomass was positively correlated with pneumatophore density. Oysters, by contrast, were highly over-dispersed and correlated with the presence/absence of pneumatophores. Epifaunal abundance and species richness were positively correlated with algal and oyster abundance, but their effects were independent. The positive effect of pneumatophore density on epifauna was primarily an indirect effect of trapping more algae. Pneumatophores did not directly influence invertebrate communities. Experiments revealed that, at very low pneumatophore densities, algal retention was insufficient to facilitate epifauna above that found on pneumatophores alone. At higher densities, however, increasing the density of pneumatophores increased algal retention, and the density and ersity of associated invertebrates. Shading by the mangrove canopy reduced algal biomass but did not modify the density-dependent nature of the cascade. Our results extend facilitation theory by showing that the density of both basal and secondary foundation species can be critical in triggering facilitation cascades. Our study also reveals that, where foundation species co-occur, multiple, independent cascades may arise from a single basal facilitator. These findings enhance our understanding of the role of density-dependent facilitation cascades in community assembly.

Relative importance of natural cues and substrate morphology for settlement of the New Zealand Greenshell™ mussel, Perna canaliculus

Publisher: Elsevier BV

Date: 09-2011

DOI: 10.1016/J.AQUACULTURE.2011.06.026

Spatial variation in the biotic and abiotic filters of oyster recruitment: Implications for restoration

Publisher: Wiley

Date: 07-01-2022

DOI: 10.1111/1365-2664.14107

Abstract: Attempts to restore marine ecosystems are increasing, but the success of projects remains variable. For marine invertebrates, the establishment of self‐sustaining populations requires a larval supply as well as conditions that permit recruitment. Abiotic and biotic conditions that determine recruitment can vary across environmental gradients and have opposing or reinforcing effects. We assessed how predation and tidal inundation influence recruitment of the reef‐forming oyster, Saccostrea glomerata, at 15 sites, 5 estuaries and 8 degrees of latitude in eastern Australia. Oysters recruited to all 15 sites, but their density displayed spatially variable effects of tidal inundation and caging. Effects of tidal inundation and caging were weakest at the two lower‐latitude estuaries where recruitment was low overall, average temperature and turbidity were high and dissolved oxygen low. At higher‐latitude estuaries, where abiotic conditions were more favourable for recruitment, recruit density displayed tidal elevation gradients that were dependent on caging and time. Initially, recruit density decreased with tidal inundation (and exposure to finfish predators), in the uncaged but not the caged treatment. However, over time the elevation gradient disappeared, and recruitment and survival of oysters was greater in caged than uncaged treatments irrespective of elevation. Synthesis and applications . Our results suggest that both abiotic (i.e. temperature, turbidity and dissolved oxygen) and biotic (i.e. predation) factors can negatively influence oyster recruitment and, hence, restoration success. Consequently, oyster reef restoration projects should be planned to prioritise sites with low turbidity, high dissolved oxygen and low predation unless these stressors can be mitigated. Restoration projects that are designed with knowledge of local stressors are more likely to be successful.

Intraspecific diversity in prey body size influences survivorship by conferring resistance to predation

Publisher: Wiley

Date: 04-2020

DOI: 10.1002/ECS2.3106

Positive versus negative effects of an invasive ecosystem engineer on different components of a marine ecosystem

Publisher: Wiley

Date: 30-10-2012

DOI: 10.1111/J.1600-0706.2012.20868.X

Heterogeneity within and among co-occurring foundation species increases biodiversity

Publisher: Springer Science and Business Media LLC

Date: 31-01-2022

DOI: 10.1038/S41467-022-28194-Y

Abstract: Habitat heterogeneity is considered a primary causal driver underpinning patterns of ersity, yet the universal role of heterogeneity in structuring bio ersity is unclear due to a lack of coordinated experiments testing its effects across geographic scales and habitat types. Furthermore, key species interactions that can enhance heterogeneity, such as facilitation cascades of foundation species, have been largely overlooked in general bio ersity models. Here, we performed 22 geographically distributed experiments in different ecosystems and biogeographical regions to assess the extent to which variation in bio ersity is explained by three axes of habitat heterogeneity: the amount of habitat, its morphological complexity, and capacity to provide ecological resources (e.g. food) within and between co-occurring foundation species. We show that positive and additive effects across the three axes of heterogeneity are common, providing a compelling mechanistic insight into the universal importance of habitat heterogeneity in promoting bio ersity via cascades of facilitative interactions. Because many aspects of habitat heterogeneity can be controlled through restoration and management interventions, our findings are directly relevant to bio ersity conservation.

Variation in the density and body size of a threatened foundation species across multi‐spatial scales

Publisher: Wiley

Date: 18-05-2022

DOI: 10.1111/REC.13670

Abstract: Population characteristics (e.g. density and body sizes) of foundation species can affect their own persistence and provisioning of ecosystem functions. Understanding the drivers of population characteristics of foundation species at multiple spatial scales is therefore critical for maximizing ecosystem functions of restored habitats. We analyzed variation in population characteristics (densities, 95th percentile, and median lengths of live oysters) of the Sydney rock oyster, Saccostrea glomerata , on remnant oyster reefs at regional scales (among three estuaries) along an approximately 250 km of coastline in New South Wales, Australia. We then analyzed how population characteristics were further related to spatial attributes at smaller spatial scales including within‐patches (rugosity, distance to patch‐edge, and elevation), whole‐patches (size and shape), and among‐patch (connectivity) within each estuary. The densities and body sizes of S. glomerata were related to spatial attributes occurring within‐patch (e.g. elevation), whole‐patch (e.g. shape), and landscape (i.e. connectivity) scales, but these relationships varied among estuaries. The greatest variation in oyster density and size occurred at regional scales, suggesting that processes acting at larger spatial scales (e.g. water quality and/or climate) set the context for smaller scale influences on oyster characteristics. Our results highlight the potential importance of incorporating site‐specific, spatial attributes in the design of restored oyster reefs to maximize ecosystem services and functions provided by restoration efforts.

Below‐ground ecosystem engineers enhance biodiversity and function in a polluted ecosystem

Publisher: Wiley

Date: 31-05-2022

DOI: 10.1111/1365-2664.14221

Abstract: Many important ecosystem functions are underpinned by below‐ground bio ersity and processes. Marine sediments, one of the most abundant habitats on earth, are essential to the mineralisation of organic matter. However, they are increasingly polluted by urban activities leading to the loss of bio ersity and the functions they provide. While traditional sediment remediation strategies are focussed on microbial and engineering solutions, we propose that the reintroduction of below‐ground ecosystem engineers (bioturbators) is important to rehabilitate polluted sediments and drive recovery of their functions in urban coastal ecosystems. We tested this notion by introducing bioturbators to nutrient polluted sediments to assess their survival, as well as their capacity to drive bio ersity and oxygenation and their potential to remediate nutrient pollution. Polychaete worms Diopatra aciculata and clams Katelysia sp. were added to mesocosms (ex‐situ), and the worms also added to experimental plots in‐situ. Potential for remediation was assessed with measures of nutrient content. All animals survived when introduced to polluted sediments and showed no evidence of sub‐lethal effects. Worms oxygenated sediments and reduced organic matter content by up to 50% in‐situ. The worms also drove shifts in the receiving communities at all locations and increased the number of taxa at one location. On the other hand, the effects of clams were variable, showing opposite effects in organic matter content at different sites and levels of pollution. Synthesis and applications . Global seafloor habitats are becoming increasingly degraded and novel strategies that combine bio ersity restoration with remediation are urgently needed to return function. Tube‐building bioturbators can stimulate nutrient processing in sediments proving multiple functional outcomes, but these effects are dependent on the receiving environment. In areas with medium levels of pollution, they can kick‐start recovery in a feedback loop whereby bioturbation increases oxygenation and nutrient remediation, shifting sediment bio ersity and contributing to further recovery. This can drive long‐term changes in sediment communities, particularly in urban areas where unvegetated sediments are conspicuous.

Mechanisms influencing the spread of a native marine alga

Publisher: Public Library of Science (PLoS)

Date: 10-04-2014

DOI: 10.1371/JOURNAL.PONE.0094647

Secondary foundation species enhance biodiversity

Publisher: Springer Science and Business Media LLC

Date: 05-03-2018

DOI: 10.1038/S41559-018-0487-5

Abstract: It has long been recognized that primary foundation species (FS), such as trees and seagrasses, enhance bio ersity. Among the species facilitated are secondary FS, including mistletoes and epiphytes. Case studies have demonstrated that secondary FS can further modify habitat-associated organisms ('inhabitants'), but their net effects remain unknown. Here we assess how inhabitants, globally, are affected by secondary FS. We extracted and calculated 2,187 abundance and 397 richness Hedges' g effect sizes from 91 and 50 publications, respectively. A weighted meta-analysis revealed that secondary FS significantly enhanced the abundance and richness of inhabitants compared to the primary FS alone. This indirect facilitation arising through sequential habitat formation was consistent across environmental and experimental conditions. Complementary unweighted analyses on log response ratios revealed that the magnitude of these effects was similar to the global average strength of direct facilitation from primary foundation species and greater than the average strength of trophic cascades, a widely recognized type of indirect facilitation arising through sequential consumption. The finding that secondary FS enhance the abundance and richness of inhabitants has important implications for understanding the mechanisms that regulate bio ersity. Integrating secondary FS into conservation practice will improve our ability to protect bio ersity and ecosystem function.

Native species behaviour mitigates the impact of habitat-forming invasive seaweed

Publisher: Springer Science and Business Media LLC

Date: 30-03-2010

DOI: 10.1007/S00442-010-1608-2

Abstract: Habitat-forming invasive species cause large, novel changes to the abiotic environment. These changes may elicit important behavioural responses in native fauna, yet little is known about mechanisms driving this behaviour and how such trait-mediated responses influence the fitness of native species. Low dissolved oxygen is a key abiotic change created by the habitat-forming invasive seaweed, Caulerpa taxifolia, which influences an important behavioural response (burrowing depth) in the native infaunal bivalve Anadara trapezia. In Caulerpa-colonised areas, Anadara often emerged completely from the sediment, and we experimentally demonstrate that water column hypoxia beneath the Caulerpa canopy is the mechanism instigating this "pop-up" behaviour. Importantly, pop-up in Caulerpa allowed similar survivorship to that in unvegetated sediment however, when we prevented Anadara from popping-up, they suffered >50% mortality in just 1 month. Our findings not only highlight the substantial environmental alteration by Caulerpa, but also an important role for the behaviour of native species in mitigating the effects of habitat-forming invasive species.

Below‐ground processes control the success of an invasive seaweed

Publisher: Wiley

Date: 10-04-2018

DOI: 10.1111/1365-2745.12966

Positive cascading effects of epiphytes enhance the persistence of a habitat‐forming macroalga and the biodiversity of the associated invertebrate community under increasing stress

Publisher: Wiley

Date: 16-11-2020

DOI: 10.1111/1365-2745.13539

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

Publisher: Springer Science and Business Media LLC

Date: 15-02-2018

DOI: 10.1007/S10530-018-1685-4

Belowground eco-restoration of a suburban waste-storage landscape: Earthworm dynamics in grassland and in a succession of woody vegetation covers

Publisher: Elsevier BV

Date: 12-2013

DOI: 10.1016/J.LANDURBPLAN.2013.06.007

Incorporating marine macrophytes in plant–soil feedbacks: Emerging evidence and opportunities to advance the field

Publisher: Wiley

Date: 12-11-2020

DOI: 10.1111/1365-2745.13536

Discovery Projects - Grant ID: DP130101113

Start Date: 06-2013

End Date: 12-2017

Amount: $325,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP180100732

Start Date: 03-2020

End Date: 09-2023

Amount: $330,000.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT140100322

Start Date: 08-2014

End Date: 07-2019

Amount: $762,812.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP130100364

Start Date: 04-2014

End Date: 04-2017

Amount: $668,057.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200200220

Start Date: 06-2022

End Date: 06-2025

Amount: $643,998.00

Funder: Australian Research Council