•The degradation of coral reefs worldwide calls for novel restoration methodologies.•The low-cost reef restoration (gardening tenet) is based on silviculture rationale.•Mid-water nurseries ...successfully farmed 86 species and above 100000 colonies.•Novel transplantation methodologies have been recently developed.•Transplanted and nursery farmed corals reveal ecological engineering aspects.
The coral reefs worldwide are exposed to multiple anthropogenic threats and persisting global change impacts, causing continuous degradation, also calling for the development of novel restoration methodologies. Of the most promising emerging approaches, deriving its rationale from silviculture, is the low-cost ‘gardening concept’, guided by a two-step restoration operation: (a) mid-water nursery phase, where coral-nubbins are farmed and (b) transplantation of nursery-farmed colonies. Tested worldwide, at least 86 coral-species and over 100000 colonies were successfully farmed in different archetype nurseries, and several novel transplantation methodologies were developed. A number of unanticipated emerged outcomes were the immediate establishment of coral infaunal biodiversity in nurseries, the development of nurseries into ‘larval dispersion hubs’ and the enhanced reproduction of transplanted coral colonies. Altogether, and in addition to envisaged results (e.g., high survivorship, fast coral growth), results attest that the gardening-toolbox could serve as a ubiquitous ecological engineering platform for restoration on a global scale.
The accelerating marks of climate change on coral-reef ecosystems, combined with the recognition that traditional management measures are not efficient enough to cope with climate change tempo and ...human footprints, have raised a need for new approaches to reef restoration. The most widely used approach is the “coral gardening” tenet; an active reef restoration tactic based on principles, concepts, and theories used in silviculture. During the relatively short period since its inception, the gardening approach has been tested globally in a wide range of reef sites, and on about 100 coral species, utilizing hundreds of thousands of nursery-raised coral colonies. While still lacking credibility for simulating restoration scenarios under forecasted climate change impacts, and with a limited adaptation toolkit used in the gardening approach, it is still deficient. Therefore, novel restoration avenues have recently been suggested and devised, and some have already been tested, primarily in the laboratory. Here, I describe seven classes of such novel avenues and tools, which include the improved gardening methodologies, ecological engineering approaches, assisted migration/colonization, assisted genetics/evolution, assisted microbiome, coral epigenetics, and coral chimerism. These are further classified into three operation levels, each dependent on the success of the former level. Altogether, the seven approaches and the three operation levels represent a unified active reef restoration toolbox, under the umbrella of the gardening tenet, focusing on the enhancement of coral resilience and adaptation in a changing world.
The continuous degradation of coral reef ecosystems on a global level, the disheartening expectations of a gloomy future for reefs' statuses, the failure of traditional conservation acts to revive ...most of the degrading reefs and the understanding that it is unlikely that future reefs will return to historic conditions, all call for novel management approaches. Among the most effective approaches is the "gardening" concept of active reef restoration, centered, as in silviculture, on a two-step restoration process (nursery and transplantation). In the almost two decades that passed from its first presentation, the "gardening" tenet was tested in a number of coral reefs worldwide, revealing that it may reshape coral reef communities (and associated biota) in such a way that novel reef ecosystems with novel functionalities that did not exist before are developed. Using the "gardening" approach as a climate change mediator, four novel ecosystem engineering management approaches are raised and discussed in this article. These include the take-home lessons approach, which considers the critical evaluation of reef restoration outcomes; the genetics approach; the use of coral nurseries as repositories for coral and reef species; and an approach that uses novel environmental engineering tactics. Two of these approaches (take-home lessons and using coral nurseries as repositories for reef dwelling organisms) already consider the uncertainty and the gaps in our knowledge, and they are further supported by the genetic approach and by the use of novel environmental engineering tactics as augmenting auxiliaries. Employing these approaches (combined with other novel tactics) will enhance the ability of coral reef organisms to adaptably respond to climate change.
The scientific discipline of active restoration of denuded coral reef areas has drawn much attention in the past decade as it became evident that this ecosystem does not often recover naturally from ...anthropogenic stress without manipulation. Essentially, the choices are either the continuous degradation of the reefs or active restoration to encourage reef development. As a result, worldwide restoration operations during the past decade have been recognized as being a major tool for reef rehabilitation. This situation has also stirred discussions and debates on the various restoration measures suggested as management options, supplementary to the traditional conservation acts. The present essay reviews past decade's (1994−2004) approaches and advances in coral reef restoration. While direct coral transplantation is still the primer vehicle of operations used, the concept of in situ and ex situ coral nurseries (the gardening concept), where coral materials (nubbins, branches, spats) are maricultured to a size suitable for transplantation, has been gaining recognition. The use of nubbins (down to the size of a single or few polyps) has been suggested and employed as a unique technique for mass production of coral colonies. Restoration of ship grounding sites and the use of artificial reefs have become common tools for specific restoration needs. Substrate stabilization, 3-D structural consideration of developing colonies, and the use of molecular/biochemical tools are part of novel technology approaches developed in the past decade. Economic considerations for reef restoration have become an important avenue for evaluating success of restoration activities. It has been suggested that landscape restoration and restoration genetics are important issues to be studied. In the future, as coral reef restoration may become the dominant conservation act, there would be the need not only to develop improved protocols but also to define the conceptual bases.
The current best management tools employed in coral reefs worldwide do not achieve conservation objectives as coral reefs continue to degrade. Even improved reef management helps, at best, to reduce ...the degradation pace, whereas the worsening global changes foretell a dismal fate for coral reefs. The assertion made here is that the prospect for reefs’ future is centered on omnipresent acceptance of restoration, an ‘active’ management instrument. A recent promising such tool is the ‘gardening concept’, influenced by the well-established scientific discipline of terrestrial forestation. This notion is supported by a two-step protocol. The first step entails rearing coral “seedlings”, in specially designed underwater nurseries, to transplantable size, before applying the second step, out-planting into damaged areas of the nursery-farmed coral colonies. Only the establishment of large-scale nurseries and transplantation actions, together with conventional management tools, will be able to cope with extensive reef degradation on the global scale.
Background
All-inclusive DNA-barcoding libraries in the storage and analysis platform of the BOLD (Barcode of Life Data) system are essential for the study of the marine biodiversity and are ...pertinent for regulatory purposes, including ecosystem monitoring and assessment, such as in the context of the EU Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). Here, we investigate knowledge gaps in the lists of DNA barcoded organisms within two inventories, Cnidaria (Anthozoa and Hydrozoa) and Ascidiacea from the reference libraries of the European Register of Marine Species (ERMS) dataset (402 ascidians and 1200 cnidarian species). ERMS records were checked species by species, against publicly available sequence information and other data stored in BOLD system. As the available COI barcode data adequately cover just a small fraction of the ERMS reference library, it is of importance to employ quality control on existing data, to close the knowledge gaps and purge errors off BOLD.
Results
Results revealed that just 22.9% and 29.2% of the listed ascidians and cnidarians species, respectively, are BOLD barcodes of which 58.4% and 52.3% of the seemingly barcoded species, respectively, were noted to have complete BOLD pages. Thus, only 11.44% of the tunicate and 17.07% of the cnidarian data in the ERMS lists are of high quality. Deep analyses revealed seven common types of gaps in the list of the barcoded species in addition to a wide range of discrepancies and misidentifications, discordances, and errors primarily in the GenBank mined data as with the BINs assignments, among others.
Conclusions
Gap knowledge in barcoding of important taxonomic marine groups exists, and in addition, quality management elements (quality assurance and quality control) were not employed when using the list for national monitoring projects, for regulatory compliance purposes and other purposes. Even though BOLD is the most trustable DNA-barcoding reference library, worldwide projects of DNA barcoding are needed to close these gaps of mistakes, verifications, missing data, and unreliable sequencing labs. Tight quality control and quality assurance are important to close the knowledge gaps of Barcoding of the European recommended ERMS reference library.
Why has histo-incompatibility arisen in evolution and can cause self-intolerance? Compatible/incompatible reactions following natural contacts between genetically-different (allogeneic) colonies of ...marine organisms have inspired the conception that self–nonself discrimination has developed to reduce invasion threats by migratory foreign germ/somatic stem cells, in extreme cases resulting in conquest of the whole body by a foreign genome. Two prominent model species for allogeneic discrimination are the marine invertebrates
Hydractinia
(Cnidaria) and
Botryllus
(Ascidiacea). In
Hydractinia
, self–nonself recognition is based on polymorphic surface markers encoded by two genes (
alr1, alr2
), with self recognition enabled by homophilic binding of identical ALR molecules. Variable expression patterns of
alr
alleles presumably account for the first paradigm of autoaggression in an invertebrate. In
Botryllus,
self–nonself recognition is controlled by a single polymorphic gene locus (
BHF
) with hundreds of codominantly expressed alleles. Fusion occurs when both partners share at least one
BHF
allele while rejection develops when no allele is shared. Molecules involved in allorecognition frequently contain immunoglobulin or Ig-like motifs, case-by-case supplemented by additional molecules enabling homophilic interaction, while the mechanisms applied to destroy allogeneic grafts or neighbors include taxon-specific tools besides common facilities of natural immunity. The review encompasses comparison with allorecognition in mammals based on MHC-polymorphism in transplantation and following feto-maternal cell trafficking.
Humans have intensively sailed the Mediterranean and European Atlantic waters throughout history, from the upper Paleolithic until today and centuries of human seafaring have established complex ...coastal and cross-seas navigation networks. Historical literature revealed three major long-lasting maritime routes (eastern, western, northern) with four commencing locations (Alexandria, Venice, Genoa, Gibraltar) and a fourth route (circum-Italian) that connected between them. Due to oceangoing and technological constraints, most voyages were coastal, lasted weeks to months, with extended resting periods, allowing the development of fouling organisms on ship hulls. One of the abiding travellers in maritime routes is the colonial ascidian Botryllus schlosseri already known since the eighteenth century in European and Mediterranean ports. This species, was almost certainly one of the common hull fouling travellers in all trade routes for centuries. Employing COI haplotypes (1008 samples) and microsatellite alleles (995 samples) on colonies sampled from 64 pan-European sites, present-day Botryllus populations in the Mediterranean Sea/European Atlantic revealed significant segregation between all four maritime routes with a conspicuous partition of the northern route. These results reveal that past anthropogenic transports of sedentary marine species throughout millennia long seafaring have left their footprint on contemporary seascape genetics of marine organisms.
Chimerism is a coalescence of conspecific genotypes. Although common in nature, fundamental knowledge, such as the spatial distribution of the genotypes within chimeras, is lacking. Hence, we ...investigated the spatial distribution of conspecific genotypes within the brooding coral Stylophora pistillata, a common species throughout the Indo-Pacific and Red Sea. From eight gravid colonies, we collected planula larvae that settled in aggregates, forming 2-3 partner chimeras. Coral chimeras grew in situ for up to 25 months. Nine chimeras (8 kin, 1 non-related genotypes) were sectioned into 7-17 fragments (6-26 polyps/fragment), and genotyped using eight microsatellite loci. The discrimination power of each microsatellite-locus was evaluated with 330 'artificial chimeras,' made by mixing DNA from three different S. pistillata genotypes in pairwise combinations. In 68% of 'artificial chimeras,' the second genotype was detected if it constituted 5-30% of the chimera. Analyses of S. pistillata chimeras revealed that: (a) chimerism is a long-term state; (b) conspecifics were intermixed (not separate from one another); (c) disproportionate distribution of the conspecifics occurred; (d) cryptic chimerism (chimerism not detected via a given microsatellite) existed, alluding to the underestimation of chimerism in nature. Mixed chimerism may affect ecological/physiological outcomes for a chimera, especially in clonal organisms, and challenges the concept of individuality, affecting our understanding of the unit of selection.
When it comes to aging, some colonial invertebrates present disparate patterns from the customary aging phenomenon in unitary organisms, where a single senescence phenomenon along ontogeny culminates ...in their inevitable deaths. Here we studied aging processes in 81 colonies of the marine urochordate Botryllus schlosseri each followed from birth to death (over 720 days). The colonies were divided between three life history strategies, each distinct from the others based on the presence/absence of colonial fission: NF (no fission), FA (fission develops after the colony reaches maximal size), and FB (fission develops before the colony reaches maximal size). The study revealed recurring patterns in sexual reproductive statuses (hermaphroditism and male-only settings), colonial vigor, and size. These recurring patterns, collectively referred to as an Orshina, with one or more 'astogenic segments' on the genotype level. The combination of these segments forms the Orshina rhythm. Each Orshina segment lasts about three months (equivalent to 13 blastogenic cycles), and concludes with either the colonial death or rejuvenation, and is manipulated by absence/existing of fission events in NF/FA/FB strategies. These findings indicate that reproduction, life span, death, rejuvenation and fission events are important scheduled biological components in the constructed Orshina rhythm, a novel aging phenomenon.
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