Summary: In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world‐wide meta‐analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success. The meta‐analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37%). Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment. Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large‐scale planting increases trial survival – large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large‐scale trial increases population growth rate by enhancing self‐sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self‐sustaining feedback in concert increase success of seagrass restoration.

Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted in accelerated global losses to ecosystem services in coastal waters. Seagrass meadows can be extensive (hundreds of square kilometers) and long-lived (thousands of years), with the meadows persisting predominantly through vegetative (clonal) growth. They also invest a large amount of energy in sexual reproduction. In this article, we explore the role that sexual reproduction, pollen, and seed dispersal play in maintaining species distributions, genetic diversity, and connectivity among seagrass populations. We also address the relationship between long-distance dispersal, genetic connectivity, and the maintenance of genetic diversity that may enhance resilience to stresses associated with seagrass loss. Our reevaluation of seagrass dispersal and recruitment has altered our perception of the importance of long-distance dispersal and has revealed extensive dispersal at scales much larger than was previously thought possible.Gary A. Kendrick, Michelle Waycott, Tim J. B. Carruthers, Marion L. Cambridge, Renae Hovey, Siegfried L. Krauss, Paul S. Lavery, Donald H. Les, Ryan J. Lowe, Oriol Mascaró I Vidal, Jillian L. S. Ooi, Robert J. Orth, David O. Rivers, Leonardo Ruiz-Montoya, Elizabeth A. Sinclair, John Statton, Jent Kornelis van Dijk and Jennifer J. Verdui

Today there is a growing need to develop reliable, sustainable, and ecofriendly protocols for manufacturing a wide range of metal and metal oxide nanoparticles. The biogenic synthesis of nanoparticles via nanobiotechnology based techniques has the potential to deliver clean manufacturing technologies. These new clean technologies can significantly reduce environmental contamination and decease the hazards to human health resulting from the use of toxic chemicals and solvents currently used in conventional industrial fabrication processes. The largely unexplored marine environment that covers approximately 70% of the earth’s surface is home to many naturally occurring and renewable marine plants. The present review summarizes current research into the biogenic synthesis of metal and metal oxide nanoparticles via marine algae (commonly known as seaweeds) and seagrasses. Both groups of marine plants contain a wide variety of biologically active compounds and secondary metabolites that enables these plants to act as biological factories for the manufacture of metal and metal oxide nanoparticles.

A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space–time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified.

Direct measurements of volume transports through Fram Strait