Seaweeds as holobionts: Current state, challenges, and potential applications.

Seaweeds play a strong ecological and economical role along the world's coastlines, where they support industries (e.g., aquaculture, bioproducts) and essential ecosystem services (e.

Disentangling direct vs indirect effects of microbiome manipulations in a habitat-forming marine holobiont.

Host-associated microbiota are critical for eukaryotic host functioning, to the extent that hosts and their associated microbial communities are often considered "holobionts". Most studies of holobionts have focused on descriptive approaches or have used model systems, usually in the laboratory, to understand host-microbiome interactions. To advance our understanding of host-microbiota interactions and their wider ecological impacts, we need experimental frameworks that can explore causation in non-model hosts, which often have highly diverse microbiota, and in their natural ecological setting (i.

Host genotype and microbiome associations in co-occurring clonal and non-clonal kelp, Ecklonia radiata.

A fundamental question in holobiont biology is the extent to which microbiomes are determined by host characteristics regulated by their genotype. Studies on the interactions of host genotype and microbiomes are emerging but disentangling the role that host genotype has in shaping microbiomes remains challenging in natural settings. Host genotypes tend to be segregated in space and affected by different environments.

The value of ecosystem services in global marine kelp forests.

While marine kelp forests have provided valuable ecosystem services for millennia, the global ecological and economic value of those services is largely unresolved. Kelp forests are diminishing in many regions worldwide, and efforts to manage these ecosystems are hindered without accurate estimates of the value of the services that kelp forests provide to human societies. Here, we present a global estimate of the ecological and economic potential of three key ecosystem services - fisheries production, nutrient cycling, and carbon removal provided by six major forest forming kelp genera (Ecklonia, Laminaria, Lessonia, Macrocystis, Nereocystis, and Saccharina).

Spatial variation in microbial communities associated with sea-ice algae in Commonwealth Bay, East Antarctica.

Antarctic sea-ice forms a complex and dynamic system that drives many ecological processes in the Southern Ocean. Sea-ice microalgae and their associated microbial communities are understood to influence nutrient flow and allocation in marine polar environments. Sea-ice microalgae and their microbiota can have high seasonal and regional (>1000 km) compositional and abundance variation, driven by factors modulating their growth, symbiotic interactions and function.

Global kelp forest restoration: past lessons, present status, and future directions.

Kelp forest ecosystems and their associated ecosystem services are declining around the world. In response, marine managers are working to restore and counteract these declines. Kelp restoration first started in the 1700s in Japan and since then has spread across the globe.

Host genetics, phenotype and geography structure the microbiome of a foundational seaweed.

Interactions between hosts and their microbiota are vital to the functioning and resilience of macro-organisms. Critically, for hosts that play foundational roles in communities, understanding what drives host-microbiota interactions is essential for informing ecosystem restoration and conservation. We investigated the relative influence of host traits and the surrounding environment on microbial communities associated with the foundational seaweed Phyllospora comosa.

Legacy Metal Contaminants and Excess Nutrients in Low Flow Estuarine Embayments Alter Composition and Function of Benthic Bacterial Communities.

Coastal systems such as estuaries are threatened by multiple anthropogenic stressors worldwide. However, how these stressors and estuarine hydrology shape benthic bacterial communities and their functions remains poorly known. Here, we surveyed sediment bacterial communities in poorly flushed embayments and well flushed channels in Sydney Harbour, Australia, using 16S rRNA gene sequencing.

Impact of marine protected areas on temporal stability of fish species diversity.

Preserving biodiversity over time is a pressing challenge for conservation science. A key goal of marine protected areas (MPAs) is to maintain stability in species composition, via reduced turnover, to support ecosystem function. Yet, this stability is rarely measured directly under different levels of protection.

The surface bacterial community of an Australian kelp shows cross-continental variation and relative stability within regions.

Epiphytic microbial communities often have a close relationship with their eukaryotic host, assisting with defence, health, disease prevention and nutrient transfer. Shifts in the structure of microbial communities could therefore have negative effects on the individual host and indirectly impact the surrounding ecosystem, particularly for major habitat-forming hosts, such as kelps in temperate rocky shores. Thus, an understanding of the structure and dynamics of host-associated microbial communities is essential for monitoring and assessing ecosystem changes.

Molecular analysis of a fungal disease in the habitat-forming brown macroalga Phyllospora comosa (Fucales) along a latitudinal gradient.

Infectious diseases affecting habitat-forming species can have significant impacts on population dynamics and alter the structure and functioning of marine ecosystems. Recently, a fungal infection was described as the causative agent of necrotic lesions on the stipe of the forest-forming macroalga Phyllospora comosa, a disease named "stipe rot" (SR). Here, we developed a quantitative PCR (qPCR) method for rapid detection and quantification of this pathogen, which was applied to evaluate the level of SR infection in eight P.

Tropicalization and kelp loss shift trophic composition and lead to more winners than losers in fish communities.

Climate-mediated species redistributions are causing novel interactions and leading to profound regime shifts globally. For species that expand their distribution in response to warming, survival depends not only on their physiological capacity, but also on the ability to coexist or be competitive within the established community. In temperate marine reefs from around the world, the range expansion of tropical species, known as 'tropicalization', has been linked to the disappearance of temperate habitat-forming kelps and shifts to dominance by low-biomass turfing algae.

Contribution of horizontal gene transfer to the functionality of microbial biofilm on a macroalgae.

Horizontal gene transfer (HGT) is thought to be an important driving force for microbial evolution and niche adaptation and has been show in vitro to occur frequently in biofilm communities. However, the extent to which HGT takes place and what functions are being transferred in more complex and natural biofilm systems remains largely unknown. To address this issue, we investigated here HGT and enrichment of gene functions in the biofilm community of the common kelp (macroalgae) Ecklonia radiata in comparison to microbial communities in the surrounding seawater.

Genomic vulnerability of a dominant seaweed points to future-proofing pathways for Australia's underwater forests.

Globally, critical habitats are in decline, threatening ecological, economic and social values and prompting calls for 'future proofing' efforts that enhance resilience to climate change. Such efforts rely on predicting how neutral and adaptive genomic patterns across a species' distribution will change under future climate scenarios, but data is scant for most species of conservation concern. Here, we use seascape genomics to characterise genetic diversity, structure and gene-environmental associations in a dominant forest-forming seaweed, Phyllospora comosa, along its entire latitudinal (12° latitude), and thermal (~14°C) range.

Provision of refugia and seeding with native bivalves can enhance biodiversity on vertical seawalls.

Recent studies have suggested that increasing habitat complexity of artificial seawalls by modifying surface heterogeneity could enhance exploitable habitat and therefore species richness and abundance. We tested the effects of adding complex tiles (with crevices/ledges) of different heterogeneity (i.e.

Emerging Solutions to Return Nature to the Urban Ocean.

Urban and periurban ocean developments impact 1.5% of the global exclusive economic zones, and the demand for ocean space and resources is increasing. As we strive for a more sustainable future, it is imperative that we better design, manage, and conserve urban ocean spaces for both humans and nature.

Interacting effects of habitat structure and seeding with oysters on the intertidal biodiversity of seawalls.

The construction of artificial structures, such as seawalls, is increasing globally, resulting in loss of habitat complexity and native species biodiversity. There is increasing interest in mitigating this biodiversity loss by adding topographic habitat to these structures, and/or seeding them with habitat-forming species. Settlement tile experiments, comparing colonisation of species to more and less complex habitats, have been used to inform eco-engineering interventions prior to their large-scale implementation.

Genomic, metabolic and phenotypic variability shapes ecological differentiation and intraspecies interactions of Alteromonas macleodii.

Ecological differentiation between strains of bacterial species is shaped by genomic and metabolic variability. However, connecting genotypes to ecological niches remains a major challenge. Here, we linked bacterial geno- and phenotypes by contextualizing pangenomic, exometabolomic and physiological evidence in twelve strains of the marine bacterium Alteromonas macleodii, illuminating adaptive strategies of carbon metabolism, microbial interactions, cellular communication and iron acquisition.

A horizon scan of priorities for coastal marine microbiome research.

Research into the microbiomes of natural environments is changing the way ecologists and evolutionary biologists view the importance of microorganisms in ecosystem function. This is particularly relevant in ocean environments, where microorganisms constitute the majority of biomass and control most of the major biogeochemical cycles, including those that regulate Earth's climate. Coastal marine environments provide goods and services that are imperative to human survival and well-being (for example, fisheries and water purification), and emerging evidence indicates that these ecosystem services often depend on complex relationships between communities of microorganisms (the 'microbiome') and the environment or their hosts - termed the 'holobiont'.

Social-environmental drivers inform strategic management of coral reefs in the Anthropocene.

Without drastic efforts to reduce carbon emissions and mitigate globalized stressors, tropical coral reefs are in jeopardy. Strategic conservation and management requires identification of the environmental and socioeconomic factors driving the persistence of scleractinian coral assemblages-the foundation species of coral reef ecosystems. Here, we compiled coral abundance data from 2,584 Indo-Pacific reefs to evaluate the influence of 21 climate, social and environmental drivers on the ecology of reef coral assemblages.

Measuring continuous compositional change using decline and decay in zeta diversity.

Incidence, or compositional, matrices are generated for a broad range of research applications in biology. Zeta diversity provides a common currency and conceptual framework that links incidence-based metrics with multiple patterns of interest in biology, ecology, and biodiversity science. It quantifies the variation in species (or OTU) composition of multiple assemblages (or cases) in space or time, to capture the contribution of the full suite of narrow, intermediate, and wide-ranging species to biotic heterogeneity.

Future climate change is predicted to affect the microbiome and condition of habitat-forming kelp.

Climate change is driving global declines of marine habitat-forming species through physiological effects and through changes to ecological interactions, with projected trajectories for ocean warming and acidification likely to exacerbate such impacts in coming decades. Interactions between habitat-formers and their microbiomes are fundamental for host functioning and resilience, but how such relationships will change in future conditions is largely unknown. We investigated independent and interactive effects of warming and acidification on a large brown seaweed, the kelp Ecklonia radiata, and its associated microbiome in experimental mesocosms.

Interactions within the microbiome alter microbial interactions with host chemical defences and affect disease in a marine holobiont.

Our understanding of diseases has been transformed by the realisation that people are holobionts, comprised of a host and its associated microbiome(s). Disease can also have devastating effects on populations of marine organisms, including dominant habitat formers such as seaweed holobionts. However, we know very little about how interactions between microorganisms within microbiomes - of humans or marine organisms - affect host health and there is no underpinning theoretical framework for exploring this.