Performance and detection range of acoustic receivers in mangrove habitats.

Acoustic telemetry has been used to monitor the movement of aquatic animals in a broad range of aquatic environments. Despite their importance, mangrove habitats are understudied for the spatial ecology of elasmobranchs, with acoustic telemetry rarely used inside mangrove habitats. One reason for this may be a general assumption that acoustic signals would not be able to be detected by receivers in such shallow, structurally complex, environments. This study tested whether acoustic receivers can be used inside mangrove habitats to track the movement of sharks and rays. Thirty-eight receivers were deployed in a mangrove system in Pioneer Bay, Orpheus Island, Great Barrier Reef, including inside mangroves, mangrove edges, and adjacent reef flat areas. The detection range and receiver performance metrics, such as code detection efficiency, rejection coefficient, and noise quotient, were examined and tested among habitats. The results highlighted that the signal from transmitters was successfully detected inside mangrove habitats as well as on the adjacent reef flat. The range to detect at least 50% of transmissions was up to 20 m inside mangroves and up to 120 m outside mangroves. The performance metrics of acoustic receivers inside the mangrove habitat were characterized by low background noise, low rejection rates, and reasonably high code detection efficiency. Furthermore, this study tested the application of this method on juvenile blacktip reef shark Carcharhinus melanopterus and mangrove whipray Urogymnus granulatus, and demonstrated that it can be used to successfully track animals inside mangrove habitat. This novel method could reveal further information on how sharks and rays use mangrove habitats.

A baseline of natural radionuclides in water and sediment of a pristine coastal ecosystem: The Xcalak and Mahahual coral reef lagoons in the western Caribbean.

In ecosystems, natural radionuclides are present in the environment and living organisms. The 238U natural decay chain produces multiple radioactive elements, such as 234U, 226Ra, 210Pb, and 210Po. These radionuclides can be found in air, water, rocks, soil, and other biotic and abiotic components, mainly derived from minerals, such as zircon and apatite. In this study, we determined the activity concentration of radionuclides from the 238U decay chain in the sediment of a coastal ecosystem on the southern Mexican coast in the western Caribbean, an ecosystem minimally affected by industrial activities. Methods included high-resolution gamma-ray spectrometry and alpha-particle spectrometry. Results showed that the sediment samples had an activity concentration range of 18.2-36.6 Bq/kg for 238U, 25.0-41.4 Bq/kg for 234U, 10.1-37.3 Bq/kg for 210Pb, and 29.9-46.0 Bq/kg for 210Po. Water samples ranged between 17.9 and 36.3 mBq/L and 27.9-66.0 mBq/L for 238U and 234U, respectively. The activity concentration of these radionuclides in the sediment and water of this area is compared with that of other coral reefs worldwide, providing a radiometric baseline for comparison purposes.

Exploring depth-related patterns of sponge diversity and abundance in marginal reefs.

Marine sponges play a vital role in the reef's benthic community; however, understanding how their diversity and abundance vary with depth is a major challenge, especially on marginal reefs in areas deeper than 30 m. To help bridge this gap, we used underwater videos at 24 locations between 2- and 62-meter depths on a marginal reef system in the Southwestern Atlantic to investigate the effect of depth on the sponge metacommunity. Specifically, we quantified the abundance, density, and taxonomic composition of sponge communities, and decomposed their gamma (γ) diversity into alpha (α) and beta (ß) components. We also assessed whether beta diversity was driven by species replacement (turnover) or by nesting of local communities (nestedness). We identified 2020 marine sponge individuals, which belong to 36 species and 24 genera. As expected, deep areas (i.e., those greater than 30 m) presented greater sponge abundance and more than eightfold the number of sponges per square meter compared to shallow areas. About 50% of the species that occurred in shallow areas (<30 m) also occurred in deep areas. Contrarily to expectations, alpha diversity of rare (0 D α), typical (1 D α), or dominant (2 D α) species did not vary with depth, but the shallow areas had greater beta diversity than the deep ones, especially for typical (1 D ß) and dominant (2 D ß) species. Between 92.7% and 95.7% of the beta diversity was given by species turnover both inside and between shallow and deep areas. Our results support previous studies that found greater sponge abundance and density in deep areas and reveal that species sorting is stronger at smaller depths, generating more beta diversity across local communities in shallow than deep areas. Because turnover is the major driver at any depth, the entire depth gradient should be considered in management and conservation strategies.

Persistent and Bioaccumulative Halogenated Natural Products in Various Tropical Reef Fish Species from the Seychelles, Western Indian Ocean.

Gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) was used to quantify and compare halogenated natural products (HNPs) and selected anthropogenic persistent organic pollutants (POPs) in individual samples of 17 fish species from the Seychelles (Western Indian Ocean). The sum-HNP amounts (9.5-1100 ng/g lipid mass (lm)) were between 1 and 2 orders of magnitude higher than those of the sum of seven abundant polychlorinated biphenyl (PCB) congeners (0.2-15 ng/g lm) and dichlorodiphenyltrichloroethane-related compounds (DDTs) (<1.1-43 ng/g lm). Within the group of HNPs, the two tetrabrominated phenoxyanisoles (aka methoxylated diphenyl ethers, MeO-BDEs), 2'-MeO-BDE 68 ≫ 6-MeO-BDE 47, were predominant in most cases. Pearson correlation analysis showed that MeO-BDE levels were positively correlated with less abundant HNPs (2,2'-diMeO-BB 80, 2',6-diMeO-BDE 68, and Br6-DBP) (p < 0.01). Accordingly, HNPs, rather than PCBs and DDTs, were the predominant polyhalogenated contaminants in the current species.

Effectiveness of artificial reefs in enhancing phytoplankton community dynamics: A meta-analysis.

Artificial reefs (ARs) are widespread globally and play a positive role in enhancing fish communities and restoring habitat. However, the effect of ARs on phytoplankton, which are fundamental to the marine food chain, remains inconclusive. Conducting a literature review and meta-analysis, this study investigates how ARs influence phytoplankton community dynamics by comparing the biomass, density, and diversity of phytoplankton between ARs and natural water bodies across varying deployment durations, constituent materials, and climatic zones. The study findings suggest that, overall, ARs enhance the biomass, density, and diversity of phytoplankton communities, with no significant differences observed compared to natural water bodies. The enhancement effect of ARs on phytoplankton communities becomes progressively more pronounced with increasing deployment time, with the overall status of phytoplankton communities being optimal when artificial reefs are deployed for 5 years or longer. Concrete and stone ARs can significantly enhance the biomass and diversity of phytoplankton, respectively. The effect of ARs on phytoplankton diversity is unrelated to climatic zones. However, deploying ARs in temperate waters significantly enhances phytoplankton biomass, while in tropical waters, it significantly reduces phytoplankton density. The research findings provide practical implications for the formulation of artificial reef construction strategies tailored to the characteristics of different aquatic ecosystems, emphasizing the need for long-term deployment and appropriate material selection. This study offers a theoretical basis for optimizing AR design and deployment to achieve maximum ecological benefits.

Microplastic pollution status in the coral reef ecosystems on the Southern and Western coasts of Sri Lanka during the Southwest monsoon.

We investigated the microplastics (MP) abundance, characteristics and pollution severity in the six coral reef ecosystems along the southern and western coasts of Sri Lanka during the southwest monsoon. The small blue-coloured fibres dominated within coral reefs and reef environments. The average coral, surface water and surface sediment MP concentration were 806.64 ± 93.72 particles kg-1ww, 23.42 ± 5.01 particles m-3, and 54.11 ± 8.04 particles kg-1dw, respectively. Coral MP concentration was significantly correlated with surface water (r = 0.65) and surface sediments (r = 0.59) indicating that the reef environment was the source of coral MP enrichment. Coral MP concentration was spatially different (p < 0.05) which may likely be due to the changes in winds, waves, coral biology and plastic sources. MP Pollution Load Index indicated that low MP contamination hazard. Since the presence of MP often deteriorates coral's health, further investigations are necessary to understand the MP's effects on the health of coral reef ecosystems.

Hurricanes temporarily weaken human-ecosystem linkages in estuaries.

Intense disturbances such as hurricanes may drastically affect ecosystems, producing both acute and long-term changes along coastlines. By disrupting human activities (e.g., fishing), hurricanes can provide an opportunity to quantify the effects of these activities on coastal ecosystems. We performed predator-exclusion experiments on oyster reefs in 2016, one-year before a category-4 hurricane ("Harvey") and again in 2018 one-year post-hurricane where the storm made landfall. Additionally, we examined 8 years (2011-2018) of fisheries-independent data to gauge how fishing pressure and fish populations were affected by the storm in three locations that varied in storm impacts. In the month following Hurricane Harvey, fishing effort dropped by 90% in the area with wind and flooding damage, and predatory fish species commonly targeted by anglers were 300% more abundant than the year prior to the hurricane. The locations without damage to fishing infrastructure did not experience declines in fishing pressure or changes in fish abundance, regardless of flooding disturbance. Reef fish and invertebrate communities directly affected by the storm were significantly different after the hurricane and were ~ 30% more diverse. With low fishing pressure, sportfish CPUE were 1.7-6.9 × higher immediately after the hurricane. Intermediate consumers, such as crabs that prey on oysters, were 45% less abundant and 10% smaller. These results indicate that hurricanes can temporarily disrupt human-ecosystem linkages and reconstitute top-down control by sportfish in estuarine food webs. Disturbance events that interrupt or weaken those interactions may yield indirect ecological benefits and provide insights into the effects of human activities on food webs.

Future climate warming threatens coral reef function on World Heritage reefs.

Climate change is the most significant threat to natural World Heritage (WH) sites, especially in the oceans. Warming has devastated marine faunas, including reef corals, kelp, and seagrass. Here, we project future declines in species and ecosystem functions across Australia's four WH coral reef regions. Model simulations estimating species-level abundances and probabilities of ecological persistence were combined with trait space reconstructions at "present," 2050 (+1.5°C of warming), and 2100 (+2°C) to explore biogeographical overlaps and identify key functional differences and forecast changes in function through time. Future climates varied by region, with Shark Bay projected to warm the most (>1.29°C), followed by Lord Howe, when standardized to marine park size. By 2050, ~40% of the Great Barrier Reef will exceed critical thresholds set by the warmest summer month (mean monthly maximum [MMM]), triggering mortality. Functional diversity was greatest at Ningaloo. At +1.5°C of warming, species and regions varied drastically in their functional responses, declined 20.2% in species richness (~70 extinctions) and lost functions across all reefs. At +2°C, models predicted a complete collapse of functions, consistent with IPCC forecasts. This variability suggests a bespoke management approach is needed for each region and is critical for understanding WH vulnerability to climate change, identifying thresholds, and quantifying uncertainty of impacts. This knowledge will aid in focusing management, policy and conservation actions to direct resources, rapid action, and set biodiversity targets for these reefs of global priority. As reefs reassemble into novel or different configurations, determining the winners and losers of functional space will be critical for meeting global landmark biodiversity goals.

Coral reef fish density at a tourist destination responded rapidly to COVID-19 restrictions.

Throughout the world, anthropogenic pressure on natural ecosystems is intensifying, notably through urbanisation, economic development, and tourism. Coral reefs have become exposed to stressors related to tourism. To reveal the impact of human activities on fish communities, we used COVID-19-related social restrictions in 2021. In French Polynesia, from February to December 2021, there was a series of restrictions on local activities and international tourism. We assessed the response of fish populations in terms of changes in the species richness and density of fish in the lagoon of Bora-Bora (French Polynesia). We selected sites with varying human pressures-some dedicated to tourism activities, others affected by boat traffic, and control sites with little human presence. Underwater visual surveys demonstrated that fish density and richness differed spatially and temporally. They were lowest on sites affected by boat traffic regardless of pandemic-related restrictions, and when activities were authorised; they were highest during lockdowns. Adult fish density increased threefold on sites usually affected by boat traffic during lockdowns and increased 2.7-fold on eco-tourism sites during international travel bans. Human activities are major drivers of fish density and species richness spatially across the lagoon of Bora-Bora but also temporally across pandemic-related restrictions, with dynamic responses to different restrictions. These results highlight the opportunity provided by pauses in human activities to assess their impact on the environment and confirm the need for sustainable lagoon management in Bora-Bora and similar coral reef settings affected by tourism and boat traffic.

The AutoSpawner system - Automated ex situ spawning and fertilisation of corals for reef restoration.

The restoration of reefs damaged by global and local pressures remains constrained by the scale of intervention currently feasible. Traditional methods for ex situ sexual propagation of corals produce limited materials, typically of limited genetic diversity and only sufficient for small field trials. The development and validation of new technologies to upscale and automate coral propagation is required to achieve logistically and financially feasible reef restoration at ecologically relevant scales. To address the need for upscaled production of genetically diverse material for use in reef restoration we designed an automated system (the AutoSpawner) for harvesting, fertilising and washing gametes from tropical broadcast-spawning corals. The system includes a novel high density dynamic fertilisation process, which enables the production of large numbers of fertilised coral eggs (>7 million per night for highly fecund species) without any downstream negative effects on larval quality. The functionality of the system and the quality of the produced larvae was assessed using multiple species from two coral families (Acroporidae and Merulinidae) across a range of spawning and gamete characteristics. We present the schematics and protocols required for automated sexual propagation of high-quality coral larvae using this novel system; and demonstrate that the time demands, and labour costs, associated with traditional manual-based sexual propagation of corals can be reduced by up to 113-fold using the AutoSpawner.

Distribution patterns of reef-building corals in the Northwest Pacific and their environmental drivers.

Understanding species distribution and the related driving processes is a fundamental issue in ecology. However, incomplete data on reef-building corals in the ecoregions of the South China Sea have hindered a comprehensive understanding of coral distribution patterns and their ecological drivers in the Northwest Pacific (NWP). This study investigated the coral species diversity and distribution patterns in the NWP by collecting species presence/absence data from the South China Sea and compiling an extensive species distribution database for the region, and explored their major environmental drivers. Our NWP coral database included 612 recorded coral species across 15 ecoregions. Of these, 536 coral species were recorded in the South China Sea Oceanic Islands after compilation, confirming the extraordinary coral species diversity in this ecoregion. Coral alpha diversity was found to decrease with increasing latitude in the whole NWP, while the influence of the Kuroshio Current on environmental conditions in its path results in a slower decline in species richness with latitude compared to regions within the South China Sea. Beta-diversity decomposition revealed that nestedness patterns mainly occurred between low and high latitude ecoregions, while communities within similar latitudes exhibited a turnover component, particularly pronounced at high latitudes. The impact of environmental factors on coral assemblage structure outweighed the effects of spatial distance. Temperature, especially winter temperature, and light intensity strongly influenced alpha diversity and beta diversity's nestedness component. Additionally, turbidity and winter temperature variations at high latitudes contributed to the turnover pattern observed among communities in the NWP. These findings elucidate the assembly processes and major environmental drivers shaping different coral communities in the NWP, highlighting the significant role of specific environmental filtering in coral distribution patterns and providing valuable insights for coral species conservation efforts.

Ecotoxicity threshold values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide in fresh and marine waters: Part 1. Derivation of threshold values.

Pesticide active ingredients are frequently detected in the rivers, creeks, wetlands, estuaries, and marine waters of the Great Barrier Reef (GBR) region and are one of the main contributors to poor water quality. Pesticide concentrations detected in the environment through water quality monitoring programs can be compared against estimates of ecologically "safe" concentrations (i.e., water quality guidelines) to assess the potential hazard and risk posed to aquatic ecosystems. Water quality guidelines are also required to estimate the aquatic risk posed by pesticide mixtures, which is used for the Reef 2050 Water Quality Improvement Plan pesticide target. Seventy-four pesticide active ingredients and their degradates are frequently detected in GBR catchment waterways, however many do not have water quality guidelines in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The current study derives ecotoxicity threshold values (ETVs) as unendorsed guideline values for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. The proposed ETVs have been derived using species sensitivity distributions, as recommended in the Australian and New Zealand nationally endorsed method for deriving water quality guidelines for aquatic ecosystem protection. Four ETVs were derived for each chemical with values that should theoretically protect 99, 95, 90 and 80 % of species (i.e., PC99, PC95, PC90, PC80, respectively). The PC99 and PC95 values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide were 0.49 µg/L and 4 µg/L, 0.029 µg/L and 0.45 µg/L, 0.11 µg/L and 5.8 µg/L and 0.19 µg/L and 2 µg/L, respectively. The ETVs will be used in an ecological hazard and risk assessment across GBR waterways in part two of this study. The ETVs can also be used to assess potential risk across Australia and internationally where monitoring data are available.

Quantitative assessment of reef foraminifera community from metabarcoding data.

Describing living community compositions is essential to monitor ecosystems in a rapidly changing world, but it is challenging to produce fast and accurate depiction of ecosystems due to methodological limitations. Morphological methods provide absolute abundances with limited throughput, whereas metabarcoding provides relative abundances of genes that may not correctly represent living communities from environmental DNA assessed with morphological methods. However, it has the potential to deliver fast descriptions of living communities provided that it is interpreted with validated species-specific calibrations and reference databases. Here, we developed a quantitative approach to retrieve from metabarcoding data the assemblages of living large benthic foraminifera (LBF), photosymbiotic calcifying protists, from Indonesian coral reefs that are under increasing anthropogenic pressure. To depict the diversity, we calculated taxon-specific correction factors to reduce biological biases by comparing surface area, biovolume and calcite volume, and the number of mitochondrial gene copies in seven common LBF species. To validate the approach, we compared calibrated datasets of morphological communities from mock samples with bulk reef sediment; both sample types were metabarcoded. The calibration of the data significantly improved the estimations of genus relative abundance, with a difference of ±5% on average, allowing for comparison of past morphological datasets with future molecular ones. Our results also highlight the application of our quantitative approach to support reef monitoring operations by capturing fine-scale processes, such as seasonal and pollution-driven dynamics, that require high-throughput sampling treatment.

A conceptual approach for an innovative marine animal forest apparatus that facilitates carbon sequestration and biodiversity enhancement.

Climate change, mainly caused by the indiscriminate usage of fossil fuels, is an urgent global challenge which endangers lives and livelihood of billions of people, the integrity of environmental well-being and the composition and functioning of terrestrial/marine ecosystems alike. To address this pressing concern, climate mitigation and adaptation solutions that target "carbon neutrality by 2050" becomes a crucial global mission. Yet, numerous emerged broad solutions that support biological approaches, such as tree planting, are less stable under enhanced climate change impacts (e.g., forests go on fire). Targeting to achieve the Paris Agreement goals, a wide range of blue carbon sequestering (BCS) approaches have been suggested, since they may contribute considerably to carbon neutrality. Unfortunately, most biological solutions, neglect the employment of marine animal-forests. Here I discuss the potential significance of a novel approach for marine animal forests' BCS, converting the commonly used coral nursery tool into a carbon sequestering floating reef device, a modular device that may accommodate carbon and biodiversity credits.

Novel metagenomics analysis of stony coral tissue loss disease.

Stony coral tissue loss disease (SCTLD) has devastated coral reefs off the coast of Florida and continues to spread throughout the Caribbean. Although a number of bacterial taxa have consistently been associated with SCTLD, no pathogen has been definitively implicated in the etiology of SCTLD. Previous studies have predominantly focused on the prokaryotic community through 16S rRNA sequencing of healthy and affected tissues. Here, we provide a different analytical approach by applying a bioinformatics pipeline to publicly available metagenomic sequencing samples of SCTLD lesions and healthy tissues from four stony coral species. To compensate for the lack of coral reference genomes, we used data from apparently healthy coral samples to approximate a host genome and healthy microbiome reference. These reads were then used as a reference to which we matched and removed reads from diseased lesion tissue samples, and the remaining reads associated only with disease lesions were taxonomically classified at the DNA and protein levels. For DNA classifications, we used a pathogen identification protocol originally designed to identify pathogens in human tissue samples, and for protein classifications, we used a fast protein sequence aligner. To assess the utility of our pipeline, a species-level analysis of a candidate genus, Vibrio, was used to demonstrate the pipeline's effectiveness. Our approach revealed both complementary and unique coral microbiome members compared to a prior metagenome analysis of the same dataset.

Shortened food chain length in a fished versus unfished coral reef.

Direct exploitation through fishing is driving dramatic declines of wildlife populations in ocean environments, particularly for predatory and large-bodied taxa. Despite wide recognition of this pattern and well-established consequences of such trophic downgrading on ecosystem function, there have been few empirical studies examining the effects of fishing on whole system trophic architecture. Understanding these kinds of structural impacts is especially important in coral reef ecosystems-often heavily fished and facing multiple stressors. Given the often high dietary flexibility and numerous functional redundancies in diverse ecosystems such as coral reefs, it is important to establish whether web architecture is strongly impacted by fishing pressure or whether it might be resilient, at least to moderate-intensity pressure. To examine this question, we used a combination of bulk and compound-specific stable isotope analyses measured across a range of predatory and low-trophic-level consumers between two coral reef ecosystems that differed with respect to fishing pressure but otherwise remained largely similar. We found that even in a high-diversity system with relatively modest fishing pressure, there were strong reductions in the trophic position (TP) of the three highest TP consumers examined in the fished system but no effects on the TP of lower-level consumers. We saw no evidence that this shortening of the affected food webs was being driven by changes in basal resource consumption, for example, through changes in the spatial location of foraging by consumers. Instead, this likely reflected internal changes in food web architecture, suggesting that even in diverse systems and with relatively modest pressure, human harvest causes significant compressions in food chain length. This observed shortening of these food webs may have many important emergent ecological consequences for the functioning of ecosystems impacted by fishing or hunting. Such important structural shifts may be widespread but unnoticed by traditional surveys. This insight may also be useful for applied ecosystem managers grappling with choices about the relative importance of protection for remote and pristine areas and the value of strict no-take areas to protect not just the raw constituents of systems affected by fishing and hunting but also the health and functionality of whole systems.

Okeanomitos corallinicola gen. and sp. nov. (Nostocales, Cyanobacteria), a new toxic marine heterocyte-forming Cyanobacterium from a coral reef.

Cyanobacterial mats supplanting coral and spreading coral diseases in tropical reefs, intensified by environmental shifts caused by human-induced pressures, nutrient enrichment, and global climate change, pose grave risks to the survival of coral ecosystems. In this study, we characterized Okeanomitos corallinicola gen. and sp. nov., a newly discovered toxic marine heterocyte-forming cyanobacterium isolated from a coral reef ecosystem of the South China Sea. Phylogenetic analysis, based on the 16S rRNA gene and the secondary structure of the 16S-23S rRNA intergenic region, placed this species in a clade distinct from closely related genera, that is, Sphaerospermopsis stricto sensu, Raphidiopsis, and Amphiheterocytum. The O. corallinicola is a marine benthic species lacking gas vesicles, distinguishing it from other members of the Aphanizomenonaceae family. The genome of O. corallinicola is large and exhibits diverse functional capabilities, potentially contributing to the resilience and adaptability of coral reef ecosystems. In vitro assays revealed that O. corallinicola demonstrates notable cytotoxic activity against various cancer cell lines, suggesting its potential as a source of novel anticancer compounds. Furthermore, the identification of residual saxitoxin biosynthesis function in the genome of O. corallinicola, a marine cyanobacteria, supports the theory that saxitoxin genes in cyanobacteria and dinoflagellates may have been horizontally transferred between them or may have originated from a shared ancestor. Overall, the identification and characterization of O. corallinicola provides valuable contributions to cyanobacterial taxonomy, offering novel perspectives on complex interactions within coral reef ecosystems.

Multiple events determine the distribution of fishes' early life stages in the Abrolhos Bank, Southwestern Atlantic.

Fluctuations in reef fish settlement and recruitment significantly impact local population dynamics and adult population size. We use light traps to evaluate reef fish settlement in inshore and offshore reefs in the Abrolhos Bank, in addition to the spatio-temporal distribution patterns, and environmental variables' influence. Data were collected from inshore and offshore reefs, and statistical analyses, including GLMs, PERMANOVA and nMDS, aimed to understand spatial-temporal species distribution patterns and the relationship between environmental variables. Results indicate greater species abundance and diversity offshore, influenced by winds, tides, and distance from shore, explaining 50% of larval patterns and highlighting the importance of spatial-temporal variations in early-life reef fish assemblages. However, several factors, including habitat type, quality, complexity, seascape configuration, and MPA location, may influence these patterns. Additionally, we provide evidence that commercially important species like Lutjanids use Abrolhos reef areas as nursery grounds.

Population genetics assessment of two pocilloporid coral species from the northern red sea: Implications for urbanized reef sustainability.

Understanding the genetic makeup of key coral species is vital for effective coral reef management, as heightened genetic diversity directly influences long-term survival and resilience against environmental changes. This study focused on two widespread Indo-Pacific branching corals, Pocillopora damicornis (referred as Pocillopora cf. damicornis (as identified only morphologically) and Seriatopora hystrix, by genotyping 222 and 195 colonies, respectively, from 10 sites in the northern Gulf of Eilat, Red Sea, using six and five microsatellite markers, respectively. Both species exhibited low observed heterozygosity (0.47 for P. cf. damicornis, 0.32 for S. hystrix) and similar expected heterozygosity (0.576 for P. cf. damicornis, 0.578 for S. hystrix). Pocillopora cf. damicornis showed minimal deviations from Hardy-Weinberg equilibrium (HWE) and low but positive F values, indicating high gene flow, while S. hystrix exhibited higher diversion from HWE and positive F values, suggesting isolation by distance and possible non-random mating or genetic drift. As the Gulf of Eilat undergoes rapid urbanization, this study highlights the anthropogenic impacts on the population genetics of key ecosystem engineering species and emphasizes the importance of managing genetics of Marine Protected Areas while implementing active coral reef restoration. The differences in reproductive traits between the two species (S. hystrix being a brooder, while P. cf. damicornis a broadcast spawner), underscore the need for sustainable population genetics management of the coral reefs for the future and resilience of the coral reef ecosystem of the northern Red Sea region.

Age is not just a number: How incorrect ageing impacts close-kin mark-recapture estimates of population size.

Population size is a key parameter for the conservation of animal species. Close-kin mark-recapture (CKMR) relies on the observed frequency and type of kinship among individuals sampled from the population to estimate population size. Knowledge of the age of the individuals, or a surrogate thereof, is essential for inference with acceptable precision. One common approach, particularly in fish studies, is to measure animal length and infer age using an assumed age-length relationship (a 'growth curve'). We used simulation to test the effect of misspecifying the length measurement error and the growth curve on population size estimation. Simulated populations represented two fictional shark species, one with a relatively simple life history and the other with a more complex life history based on the grey reef shark (Carcharhinus amblyrhynchos). We estimated sex-specific adult abundance, which we assumed to be constant in time. We observed small median biases in these estimates ranging from 1.35% to 2.79% when specifying the correct measurement error standard deviation and growth curve. CI coverage was adequate whenever the growth curve was correctly specified. Introducing error via misspecified growth curves resulted in changes in the magnitude of the estimated adult population, where underestimating age negatively biased the abundance estimates. Over- and underestimating the standard deviation of length measurement error did not introduce a bias and had negligible effect on the variance in the estimates. Our findings show that assuming an incorrect standard deviation of length measurement error has little effect on estimation, but having an accurate growth curve is crucial for CKMR whenever ageing is based on length measurements. If ageing could be biased, researchers should be cautious when interpreting CKMR results and consider the potential biases arising from inaccurate age inference.