Larval Dispersal Research Articles

Larval dispersal simulations and connectivity predictions for Mediterranean gorgonian species: sensitivity to flow representation and biological traits

Abstract Larval dispersal enables demographic and genetic connectivity among marine populations. For many sessile species, it is the only natural mechanism for resilience after major population disturbances, as those that have been affecting Mediterranean gorgonian species inside and outside Marine Protected Areas (MPAs). Larval dispersal simulation is a powerful tool to anticipate connectivity among populations which might be altered by modelling choices. We assessed how flow representation (resolution and vertical turbulence) and larval traits (pelagic larval duration, release timing and duration, larval vertical behaviour) influenced populations connectivity among five coastal rocky locations in the northwestern Mediterranean, four of them being designated as MPAs. We used a finer (0.3 km) and coarser (1.5 km) flow resolution in two years to assess, using a hierarchical simulation approach, the sensitivity of connectivity patterns to the above parameters. Larval traits corresponded to two gorgonian species, the neutrally buoyant Eunicella singularis and the passive sinker Paramuricea clavata. Ocean model resolution was the most influential factor on resulting connectivity patterns. When using the finer flow model resolution, connectivity patterns were equally influenced by all larval traits while vertical turbulence could be neglected. Hence, advising the design of coastal MPAs with regional connectivity estimates requires adequate flow simulation resolution.

Connectivity modelling informs metapopulation structure and conservation priorities for a reef‐building species

AbstractAimIn coastal marine systems, biogenic reef‐building species have great importance for conservation as they provide habitat for a wide range of species, promoting biodiversity, ecosystem functioning and services. Biogenic reef persistence and recovery from perturbations depend on recolonization by new recruits. Characterizing larval dispersal among distant reefs is key to understanding how connectivity shapes metapopulation structure and determines network coherence; all of which are of critical importance for effective conservation.LocationNortheast Atlantic coast and western English Channel, France.MethodsWe used a biophysical transport model to simulate larval dispersal of the reef‐building polychaete Sabellaria alveolata. We combined dispersal modelling and network analysis into a framework aiming to identify key reef areas and critical dispersal pathways, whose presence in the network is vital to its overall coherence. We evaluated changes in dispersal pathways constrained by different connectivity thresholds, i.e., minimum dispersal rate for the presence of a connection. We tested scenarios of sequential loss of reefs: randomly, by habitat quality (a score for reef status and occupancy in an area) or by betweenness centrality metric (BC; quantifying the proportion of shortest paths connecting all areas that are passing through any given area).ResultsWe found that the network of S. alveolata reefs forms two main regional clusters, the Atlantic coast and the English Channel, which are connected only through weak sporadic dispersal events. Within each cluster, the network is characterized by relatively high connectivity among neighbouring areas with reefs, maintained even under higher connectivity thresholds. Simulating scenarios of sequential loss of reefs further identified high centrality reefs, those with highest BC values, key to network coherence.Main conclusionsEffective conservation of this important reef habitat requires a network of protected areas designed to sustain a combination of locally important source reefs, and those that act as stepping stones connecting distant reefs.

Impact of the use of different temperature‐dependent larval development functions on estimates of potential large‐scale connectivity of American lobster

AbstractThe way in which the effect of temperature on the development rate of crustacean larvae is simulated in larval dispersal models potentially impacts the inferences made about population recruitment and connectivity. In this study, we contrasted dispersal and connectivity predictions made by a large‐scale dispersal model of American lobster (Homarus americanus H. Milne Edwards, 1837) larvae using three temperature‐dependent larval development functions proposed in the literature: (1) “warm‐source lab”, (2) “warm‐source field”, and (3) “cold‐source lab”. Differences in predictions using each function were contrasted in the northern (colder) and southern (warmer) portions of the species' range. Using these different development functions resulted in significant and marked differences (61.3–162.4 km in the north and 30.9–81.9 km in the south) in the distances dispersed by larvae from hatch to settlement. In general, predicted self‐seeding, retention, and local connectivity were increased, and predicted connectivity among distant locations was decreased, when a function predicting faster development was used. The field‐derived function predicted much less connectivity and decreased dispersal overall than both lab‐derived functions. The cold‐source lab function predicted more retention in northern regions, but less in southern regions, than the warm‐source lab function. Our findings indicate the need for more studies to quantify the rate at which lobster larvae develop in nature, including how this may vary over space and time.

Sea Level Rise and the Great Barrier Reef: The Future Implications on Reef Tidal Dynamics

AbstractPredicted sea‐level rise (SLR) is anticipated to alter tidal dynamics in the future and this will in turn alter coastal ecosystems, flood risk, and geomorphology. Coral reefs are bathymetrically complex environments where tides play a crucial role in larval and nutrient dispersal. This complexity makes coral reef environments challenging to simulate numerically as a large area needs to be simulated but also with high resolution to capture the complexity. To investigate the influence of SLR on tidal dynamics in coral reef systems we use an unstructured mesh numerical model, with spatially varying resolution, of the Great Barrier Reef (GBR). The present‐day conditions and a total of three future SLR scenarios are considered based on the RCP scenarios. The results focus on the major tidal constituents and tidal range. The M2 constituent generally decreases across gauge locations as sea‐level rises but S2 generally increases. O1 and K1 display small variations or no change. The tidal range experiences ±10% variation depending on the gauge location, meaning it is spatially varying and alters SLR by up to 10%. Overall, SLR will influence tidal dynamics across the GBR altering coastal flooding risk with a spatially varying impact. Management schemes should consider tidal range changes in addition to increases in extreme weather conditions to provide adequate preservation of the coastline, coastal cities and infrastructure in the future. Moreover, changes in tidal patterns and dynamics may alter the distributions of reef spores and larvae and should be included in future plans of reef management.

Benefits of measurable population connectivity metrics for area-based marine management

The dispersal of larvae by ocean currents is likely to represent an increasingly important driver of marine population dynamics across fragmented habitats. A boost in availability of larval dispersal data from biophysical simulations has therefore led to routine calculations of population connectivity metrics that are used for area-based management decision support, including the placement of Marine Protected Areas (MPAs). However, connectivity-based decision support for area-based management is often complex, highly uncertain, and the associated conservation impact rarely if ever evaluated. In combination, these challenges risk stakeholder engagement, compliance, and overall management effectiveness. Here we use a case study representing multiple key fishery species on coral reefs in Indonesia to demonstrate that consideration of larval dispersal for MPA placement decision support could be critical to recover both fish populations and fisheries from depletion, thereby mitigating potentially severe impacts on coastal communities. Importantly, we further show that MPA placement decisions can be effective even if based on comparatively simple and empirically measurable dispersal characteristics. Maximizing larval export, expressed as the contribution of larvae from MPA candidate sites to total larval settlement in surrounding areas, for example, was found to be a broadly beneficial MPA placement prioritization approach. Across investigated fish families with diverse life histories, this strategy resulted in MPA network designs that increased catches by a factor of 1.3 ± 0.3 (mean ± SD) and total fish biomass by a factor of 3.2 ± 0.3 (9.7 ± 1.2 in no-fishing areas and 1.4 ± 0.3 in fished areas) compared to conditions without effectively managed or protected areas. Our findings are relevant for both the implementation and impact evaluation of global marine conservation policies, specifically in tropical biodiversity hotspots, such as Indonesia, where coral reefs are often overfished and increasingly threatened but local communities highly dependent on sustainable fisheries.

Limited spatial rescue potential for coral reefs lost to future climate warming

AbstractAimThe aim was to determine reef connectivity and future coral cover levels under global scenarios of coral bleaching loss and potential recovery.LocationGlobal coral reefs.Time periodPresent‐day to 2100.Major taxa studiedScleractinian coral.MethodsWe used a global coral larval dispersal model that describes population connectivity among reefs at a resolution of ⅙° × ⅙° (c. 18 km × 18 km) cells. To simulate different patterns of bleaching events, we ran three scenarios at different levels of coral reef habitat loss followed by a reseeding of coral larvae from surviving reefs to simulate recovery.ResultsWe found a total of 604 distinct reef networks, but more than half of the world's reef cells are contained in six large coral reef networks (294–5,494 cells), whereas the rest form smaller networks. In the bleaching scenario where previously identified predicted climate refugia were maintained, initial connectivity was largely preserved even when 71% of global coral reef habitat was lost, but the relict reef cells were unable to reseed even 50% of former coral reef habitat because many of the relict reefs are in the same networks as each other. In scenarios where refugia were lost first or with random loss, less of the initial connectivity was maintained, but more widespread reseeding was possible because more reef cells within smaller networks were maintained.Main conclusionsOur findings highlight the importance of maintaining functional coral reef habitat outside of predicted climate refugia to sustain connectivity globally, and suggest an important role for “stepping stone” reefs between the climate refugia. Without attention to these issues of habitat loss and connectivity, much of global coral reef habitat might not be reseeded without human intervention.

Climate Change Will Fragment Florida Stone Crab Communities

Many marine species have been shown to be threatened by both ocean acidification and ocean warming which are reducing survival, altering behavior, and posing limits on physiology, especially during earlier life stages. The commercially important Florida stone crab, Menippe mercenaria, is one species that is affected by reduced seawater pH and elevated seawater temperatures. In this study, we determined the impacts of reduced pH and elevated temperature on the distribution of the stone crab larvae along the West Florida Shelf. To understand the dispersion of the larvae, we coupled the multi-scale ocean model SLIM with a larval dispersal model. We then conducted a connectivity study and evaluated the impacts of climate stressors by looking at four different scenarios which included models that represented the dispersion of stone crab larvae under: 1) present day conditions as modelled by SLIM for the temperature and NEMO-PISCES for the pH, 2) SSP1-2.6 scenario (-0.037 reduction in pH and +0.5°C compared to present-day conditions), 3) SSP2-4.5 scenario(-0.15 reduction in pH and +1.5°C) and 4) SSP5-8.5 scenario (-0.375 reduction in pH and +3.5°C). Our results show a clear impact of these climate change stressors on larval dispersal and on the subsequent stone crab distribution. Our results indicate that future climate change could result in stone crabs moving north or into deeper waters. We also observed an increase in the number of larvae settling in deeper waters (defined as the non-fishing zone in this study with depths exceeding 30 m) that are not typically part of the commercial fishing zone. The distance travelled by larvae, however, is likely to decrease, resulting in an increase of self-recruitment and decrease of the size of the sub-populations. A shift of the spawning period, to earlier in the spring, is also likely to occur. Our results suggest that habitats in the non-fishing zone cannot serve as a significant source of larvae for the habitats in the fishing zone (defined as water depth< 30 m) since there is very little exchange (< 5% of all exchanges) between the two zones. These results indicate that the stone crab populations in Florida may be susceptible to community fragmentation and that the management of the fishery should consider the potential impacts of future climate change scenarios.

Exploitation Drives Changes in the Population Connectivity of Queen Conch (Aliger gigas)

The queen conch, Aliger gigas, is an endemic and iconic marine gastropod of the Wider Caribbean region that has been harvested for thousands of years. Conch are slow-moving and require contact to mate; overfishing has reduced populations in many areas compromising its rates of reproduction. Long-range dispersal and mixing between distinct populations occur in the queen conch’s early life history stages, when pelagic larvae are transported by oceanic currents. Genetic studies suggest that gene flow between populations decreases as the distance between populations increases. Here, we assessed how the population connectivity of conch changes with spatially variable patterns of fishing exploitation by simulating larval dispersal and comparing the potential connectivity under an unexploited and a contemporary exploited reproductive scenario. Results demonstrate that reduced egg production, due to heterogeneous fishing pressure and localized depletion, significantly alters population connectivity patterns as well as the structuring of populations and metapopulations across the species’ range. This strongly suggests that estimates of contemporary demographic rates, together with estimates of reproductive output need to be included in population connectivity studies. The existence of self-sustained metapopulations of queen conch throughout the Wider Caribbean suggests that replenishment through larval dispersal occurs primarily within sub-regional spatial scales, emphasizing the need for regional and local conservation and management measures to build and protect reproductively active populations and nursery habitat across multiple jurisdictions.

Ocean acidification elicits differential bleaching and gene expression patterns in larval reef coral Pocillopora damicornis under heat stress

The successful dispersal of coral larvae is vital to the population replenishment and reef recovery and resilience. Despite that this critical early stage is susceptible to ocean warming and acidification, little is known about the responses of coral larvae to warming and acidification across different biological scales. This study explored the influences of elevated temperature (29 °C versus 33 °C) and pCO2 (500 μatm versus 1000 μatm) on brooded larvae of Pocillopora damicornis at the organismal, cellular and gene expression levels. Heat stress caused bleaching, depressed light-enhanced dark respiration, photosynthesis and autotrophy, whereas high pCO2 stimulated photosynthesis. Although survival was unaffected, larvae at 33 °C were ten-times more likely to settle than those at 29 °C, suggesting reduced capacity to disperse and differentiate suitable substrate. Remarkably, heat stress induced greater symbiont loss at ambient pCO2 than at high pCO2, while cell-specific pigment concentrations of symbionts at 33 °C increased twofold under ambient pCO2 relative to high pCO2, suggesting pCO2-dependent bleaching patterns. Considerable increases in activities of host antioxidants superoxide dismutase (SOD) and catalase (CAT) at 33 °C indicated oxidative stress, whereas lipid peroxidation and caspase activities were contained, thereby restraining larval mortality at 33 °C. Furthermore, the coral host mounted stronger transcriptional responses than symbionts. High pCO2 stimulated host metabolic pathways, possibly because of the boosted algal productivity. In contrast, host metabolic processes and symbiont photosystem genes were downregulated at 33 °C. Interestingly, the upregulation of extracellular matrix genes and glycosaminoglycan degradation pathway at 33 °C was more evident under ambient pCO2 than high pCO2, suggesting compromised host tissue integrity that could have facilitated symbiont expulsion and bleaching. Our results provide insights into how coral larvae respond to warming and acidification at different levels of biological organization, and demonstrate that ocean acidification can mediate thermal bleaching and gene expression in coral larvae under heat stress.

Development of 27 new microsatellite markers for the shanny Lipophrys pholis.

The shanny Lipophrys pholis is an intertidal fish that is widely distributed throughout the Northeast Atlantic. Characterized by limited adult mobility and a long pelagic larval duration, the shanny stands as an ideal model to better understand larval dispersal and connectivity dynamics, which are critical parameters with implications for marine conservation and management. To this aim, we developed 27 highly polymorphic microsatellite markers and characterized a population of 42 individuals, presenting an average allelic diversity of 20.1 alleles per locus and heterozygosity ranging from 0.619 to 1. This set of newly developed microsatellite markers will be useful in providing critical insights into the processes which shape L. pholis gene flow and connectivity patterns and can be used to investigate local parentage lineages.

Environmentally friendly microbeads to model the dispersal of particulates in aquatic systems

The transport of particulate matter including the gametes, larvae and propagules of reproducing organisms and other organic matter involved in nutrient/contaminant transport are important processes, yet there are few environmentally friendly methods available to examine dispersal empirically. Herein we report on the development and application of a biodegradable and non-toxic physical model, based on alginate microbeads with modifiable size, density (ρ), and colour for use in dispersal studies. Specifically, the microbeads were designed to model the size and ρ of parasitic juvenile freshwater mussels (Unionidae; ρ = 1200 kg m−3), which undergo dispersal upon excystment from fish hosts. We released the juvenile-mussel and neutrally buoyant microbeads (ρ = 1000 kg m−3) in a local river and captured them in drift nets downstream. The concentration of microbeads declined with downstream distance, but neutrally buoyant microbeads were transported farther. Analysis of microbead capture rates could be described using the patterns of several mathematical models (negative exponential, power, and turbulent transport), which were consistent with the reported dispersal of mussel larvae and other benthic macroinvertebrates. These results support the use of alginate microbeads in dispersal studies, because their environmentally friendly and customizable properties offer improvements over non-biodegradable alternatives.

Interannual fluctuations in connectivity among crab populations (Liocarcinus depurator) along the Atlantic-Mediterranean transition

An interesting evolutionary question that still remains open is the connectivity between marine populations. Marine currents can favour the dispersal of larvae or adults, but they can also produce eddies and gyres generating oceanographic fronts, thus limiting gene flow. To address this subject, we selected the Atlantic-Mediterranean transition, where several fronts are located: Gibraltar Strait (GS), Almeria-Oran Front (AOF) and Ibiza Channel (IC). Seven populations of the marine crab Liocarcinus depurator (Cadiz, West and East Alboran, Alacant, Valencia, Ebro Delta and North Catalonia) located along this transition were analysed in six consecutive years (2014–2019) using a fragment of the COI (Cytochrome Oxidase subunit I) gene. All sequences (966) belonged to two well defined haplogroups: ATL (most abundant in Atlantic waters) and MED (predominant in Mediterranean waters). Following a geographic variation, the frequency of ATL decreased significantly from Cadiz to North Catalonia. However, this variation presented steps due to the effect of oceanographic restrictions/fronts. Significant effects were recorded for GS (2015, 2017, 2018 and 2019), AOF (all years except 2018) and IC (2016). The intensity and precise location of these fronts changed over time. Multivariate analyses distinguished three main population groups: Cadiz, Alboran Sea and the remaining Mediterranean populations. These findings could be relevant to properly define Marine Protected Areas and for conservation and fisheries policies.

Reactivity, Attenuation, and Transients in Metapopulations

Transient dynamics often differ drastically from the asymptotic dynamics of systems. In this paper we analyze transient dynamics in birth-jump metapopulations where dispersal occurs immediately after birth (e.g., via larval dispersal). We address the choice of appropriate norms as well as the effect of stage structure on transient dynamics. We advocate the use of the $\ell_1$ norm, because of its biological interpretation, and extend the transient metrics of reactivity and attenuation to birth-jump metapopulations in this norm. By way of examples we compare this norm to the more commonly used $\ell_2$ norm. Our focus is the case where transient dynamics are very different than asymptotic dynamics. We provide simple examples of metapopulations where this is the case and also show how increasing the number of habitat patches can increase this difference. We then connect the reactivity and attenuation of metapopulations to the source-sink classification of habitat patches and demonstrate how to meaningfully measure reactivity when metapopulations are stage-structured, with a focus on marine metapopulations. Our paper makes three primary contributions. First, it provides guidance to readers as to the appropriate norm and scalings for studying transients in birth-jump metapopulations. Second, it provides three examples of transient behavior in metapopulations involving slow-fast systems, crawl-bys, and high dimensionality. Third, it connects the concepts of reactivity and attenuation to the source-sink classification of habitat patches more commonly found in marine metapopulations.

Genetic isolation and homogenization: Potential effects of landscape features on the population genetic structure of freshwater mussels

Dispersal, the movement of individuals from their natal population to their breeding population, has important ecological and evolutionary consequences. In lotic freshwater systems, landscape features such as barriers or connectors, can affect dispersal and thus gene flow. It is of special interest to characterize population genetic structure in the presence of impassable barriers because they can restrict dispersal and thus isolate populations. On the other hand, connectors such as man-made canals connect watersheds that would otherwise be isolated, thereby enhancing gene flow and potentially genetically homogenizing populations. Freshwater mussels (Order: Unionida), many of which are highly threatened, have a unique life history involving parasitism on host fish species for larval development and dispersal. Landscape features that affect fish passage will consequently affect mussel dispersal and the maintenance of populations and metapopulations. This manuscript explores how landscape features affect the population genetic structure and genetic diversity of the freshwater mussel species Lampsilis siliquoidea, Fatmucket, in the southwestern Lake Ontario drainage. Data from seven microsatellite loci revealed that 1) waterfalls act as barriers for gene flow between freshwater mussel populations within the same river, 2) populations above the barrier had lower genetic diversity, 3) there was no detectable effect of man-made canals on genetic diversity and, 4) populations that were not hydrologically connected by a canal were marginally more differentiated than the populations connected by a canal. Landscape features can alter the connectivity within and between drainages thus changing the scale at which management will be effective.

Early Life History and Recruitment Processes of a Tropical Anguillid Eel Anguilla marmorata to the Pacific Coast, as Revealed by Otolith Sr:Ca Ratios and Microstructure.

Recent progress in otolith microchemistry especially in strontium:calcium (Sr:Ca) ratios has revealed significant features of life histories in fishes. A catadromous eel, Anguilla marmorata, has the widest distribution among anguillid eels throughout the Indo-Pacific region. However, its dispersal and recruitment mechanisms in the ocean are still unknown. The temporal and spatial variations of early life history characteristics in a tropical anguillid eel A. marmorata were examined by means of otolith Sr:Ca ratios and microstructure to understand the larval transport and recruitment processes to the coasts in the Pacific region. Durations of the larval stage and age at recruitment to the southern part of Japan ranged from 79 to 157 d and 113 to 192, respectively. No significant differences were found between recruitment months in those parameters. The early life characteristics such as larval duration and age at recruitment were constant throughout the recruitment period in the southern part of Japan. The early life history characteristics in combination with the oceanic current regime possibly determine the larval transportation and dispersion processes and further recruitment dynamics to the Pacific coast of A. marmorata. The present study also provides useful information on its biogeographic distribution in the species as determined by otolith Sr:Ca ratios and microstructure.

Environmental Conditions along Tuna Larval Dispersion: Insights on the Spawning Habitat and Impact on Their Development Stages

Estimated larval backward trajectories of three Tuna species, namely, Atlantic Bluefin Tuna (Thunnus thynnus, Linnaeus, 1758), Bullet Tuna (Auxis Rochei, Risso, 1801) and Albacore Tuna (Thunnus alalunga, Bonnaterre, 1788) in the central Mediterranean Sea, were used to characterize their spawning habitats, and to assess the impact of changes due to the major environmental parameters (i.e., sea surface temperature and chlorophyll-a concentration) on larval development during their advection by surface currents. We assumed that the environmental variability experienced by larvae along their paths may have influenced their development, also affecting their survival. Our results showed that the Tuna larvae underwent an accelerated growth in favorable environmental conditions, impacting on the notochord development. In addition, further updated information on spawning and larval retention habitats of Atlantic Bluefin Tuna, Bullet and Albacore Tunas in the central Mediterranean Sea were delivered.

Range expansion of the invasive portunid crab Charybdis japonica in New Zealand

ABSTRACT Charybdis japonica, a large invasive portunid, has been recorded in New Zealand since its detection in the Waitematā Harbour in 2000. In this study, the distribution, invasion history, abundance and population structure were investigated for C. japonica across the North Island of New Zealand. This was done using various distribution data available, trapping across several sites and interviews with commercial fishermen. Charybdis japonica was detected in the previously uninvaded Tauranga, Ohiwa, Hokianga, Manukau Harbours and Great Barrier Island. The rate of spread for C. japonica is continuous, with harbours or estuaries hundreds of kilometres apart having detections every two to three years. Population abundances reported by commercial fishermen constantly increased, with no signs of stabilisation or decrease. Catches were male-biased, with female abundance varying seasonally. Several possible pathways and vectors may be responsible for this spread, including shipping and aquaculture, on top of dispersal of larvae by currents across the North Island. Further research is required to determine population sources, with findings providing important information for invasive species monitoring and management.

Unravelling the spatial-temporal population structure of Trachurus picturatus across the North-East Atlantic using otolith fingerprinting

The blue jack mackerel Trachurus picturatus is one of the most important pelagic fish captured in the Macaronesian islands of the Azores and Madeira. However, in the last years' landings registered substantial decreases. Fluctuations may be related to oscillations in the cohorts’ recruitment rates, although no information regarding the species movements and connectivity is available. The present study applies laser ablation inductively coupled-plasma mass spectrometry (LA-ICP-MS) to investigate the otolith chemical fingerprints (core and edge) of three cohorts sampled off the Azores, Madeira, Canaries and Peniche (Portuguese coast) in 2013, 2016 and 2019. Otoliths from juveniles (age 0+ and 1+) and adults (age 3+) were examined to infer the scale of geographical variation among fishing grounds and years. Univariate analyses showed significant differences among locations based on Li:Ca, Mg:Ca, Sr:Ca and Ba:Ca concentration ratios. Multi-elemental analyses allocated 70% (2013), 43% (2016) and 43% (2019) of the individuals to their original location based on core elemental fingerprint, and 63% (2013), 75% (2016) and 83% (2019) based on the edge elemental signature. The natal signature suggests that there is some degree of self-recruitment in the fishing grounds and that the subpopulations are connected essentially by dispersal of larvae/juveniles. Furthermore, data suggests that self-recruitment is variable among the cohorts sampled. The discrimination of individuals observed at the time of collection suggests that T. picturatus populations across the north-eastern Atlantic should be regarded as different population units and manage accordingly, as previously observed. Future works should focus on identifying the natal sources of each fishing ground and assess the impact of environmental changes on the distance and direction of larval dispersal.

Coral-bleaching responses to climate change across biological scales.

The global impacts of climate change are evident in every marine ecosystem. On coral reefs, mass coral bleaching and mortality have emerged as ubiquitous responses to ocean warming, yet one of the greatest challenges of this epiphenomenon is linking information across scientific disciplines and spatial and temporal scales. Here we review some of the seminal and recent coral‐bleaching discoveries from an ecological, physiological, and molecular perspective. We also evaluate which data and processes can improve predictive models and provide a conceptual framework that integrates measurements across biological scales. Taking an integrative approach across biological and spatial scales, using for example hierarchical models to estimate major coral‐reef processes, will not only rapidly advance coral‐reef science but will also provide necessary information to guide decision‐making and conservation efforts. To conserve reefs, we encourage implementing mesoscale sanctuaries (thousands of km2) that transcend national boundaries. Such networks of protected reefs will provide reef connectivity, through larval dispersal that transverse thermal environments, and genotypic repositories that may become essential units of selection for environmentally diverse locations. Together, multinational networks may be the best chance corals have to persist through climate change, while humanity struggles to reduce emissions of greenhouse gases to net zero.

Genetic Diversity and Population Structure of Lethrinus Lentjan (Lethrinidae) in Vietnam Based on SNP Markers

Lethrinus lentjan (Lacepède, 1802) is an important commercial species for marine fisheries in subtropical and tropical regions of the Indian and Indo-Pacific oceans. Although heavily exploited, their genetic diversity and population structuring along the Vietnam coastline are unclear. Here, we used a panel of single nucleotide polymorphisms (SNPs) generated from restriction site-associated DNA sequencing (RADseq). After removing 405 outlier loci, 1,506 putatively neutral SNPs from 62 individuals were used to assess the genetic population structure of L. lentjan. Observed/expected heterozygosity (Ho/He) within sites ranged from 0.170/0.202 (Southeast) to 0.188/0.213 (Central). Pairwise FST values, Structure and Discriminant Analysis of Principal Components (DAPC) analysis indicate the lack of spatial genetic structure, suggesting the presence of a single panmictic population. Larval dispersal by ocean currents may facilitated high gene flow of L. lentjan along the Vietnamese coastline, and Mekong River outflow may not act as the natural barrier.