Now showing items 21-40 of 1483

    • How often should dead-reckoned animal movement paths be corrected for drift?

      Gunner, Richard M.; Holton, Mark D.; Scantlebury, David M.; Hopkins, Phil; Shepard, Emily L. C.; Fell, Adam J.; Garde, Baptiste; Quintana, Flavio; Gómez-Laich, Agustina; Yoda, Ken; Yamamoto, Takashi; English, Holly; Ferreira, Sam; Govender, Danny; Viljoen, Pauli; Bruns, Angela; van Schalkwyk, O. Louis; Cole, Nik C.; Tatayah, Vikash; Börger, Luca; Redcliffe, James; Bell, Stephen H.; Marks, Nikki J.; Bennett, Nigel C.; Tonini, Mariano H.; Williams, Hannah J.; Duarte, Carlos M.; van Rooyen, Martin C.; Bertelsen, Mads F.; Tambling, Craig J.; Wilson, Rory P. (Animal Biotelemetry, Springer Science and Business Media LLC, 2021-10-16) [Article]
      Abstract Background Understanding what animals do in time and space is important for a range of ecological questions, however accurate estimates of how animals use space is challenging. Within the use of animal-attached tags, radio telemetry (including the Global Positioning System, ‘GPS’) is typically used to verify an animal’s location periodically. Straight lines are typically drawn between these ‘Verified Positions’ (‘VPs’) so the interpolation of space-use is limited by the temporal and spatial resolution of the system’s measurement. As such, parameters such as route-taken and distance travelled can be poorly represented when using VP systems alone. Dead-reckoning has been suggested as a technique to improve the accuracy and resolution of reconstructed movement paths, whilst maximising battery life of VP systems. This typically involves deriving travel vectors from motion sensor systems and periodically correcting path dimensions for drift with simultaneously deployed VP systems. How often paths should be corrected for drift, however, has remained unclear. Methods and results Here, we review the utility of dead-reckoning across four contrasting model species using different forms of locomotion (the African lion Panthera leo, the red-tailed tropicbird Phaethon rubricauda, the Magellanic penguin Spheniscus magellanicus, and the imperial cormorant Leucocarbo atriceps). Simulations were performed to examine the extent of dead-reckoning error, relative to VPs, as a function of Verified Position correction (VP correction) rate and the effect of this on estimates of distance moved. Dead-reckoning error was greatest for animals travelling within air and water. We demonstrate how sources of measurement error can arise within VP-corrected dead-reckoned tracks and propose advancements to this procedure to maximise dead-reckoning accuracy. Conclusions We review the utility of VP-corrected dead-reckoning according to movement type and consider a range of ecological questions that would benefit from dead-reckoning, primarily concerning animal–barrier interactions and foraging strategies.
    • Regionalization of the Red Sea based on phytoplankton phenology: a satellite analysis

      Kheireddine, Malika; Mayot, N.; Ouhssain, Mustapha; Jones, Burton (Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), 2021-10-15) [Article]
      The current average state of Red Sea phytoplankton phenology needs to be resolved in order to study future variations that could be induced by climate change. Moreover, a regionalization of the Red Sea could help to identify areas of interest and guide in situ sampling strategies. Here, a clustering method used 21 years of satellite surface chlorophyll-a concentration observations to characterize similar regions of the Red Sea. Four relevant phytoplankton spatiotemporal patterns (i.e., bio-regions) were found and linked to biophysical interactions occurring in their respective areas. Two of them, located in the northern part the Red Sea, were characterized by a distinct winter-time phytoplankton bloom induced by mixing events or associated with a convergence zone. The other two, located in the southern regions, were characterized by phytoplankton blooms in summer and winter which might be under the influence of water advected into the Red Sea from the Gulf of Aden in response to the seasonal monsoon winds. Some observed inter-annual variabilities in these bio-regions suggested that physical mechanisms could be highly variable in response to variations in air-sea heat fluxes and ENSO phases in the northern and southern half of the Red Sea, respectively. This study reveals the importance of sustaining in situ measurements in the Red Sea to build a full understanding about the physical processes that contribute to phytoplankton production in this basin.
    • Lipid Remodeling Reveals the Adaptations of a Marine Diatom to Ocean Acidification

      Jin, Peng; Liang, Zhe; Lu, Hua; Pan, Jinmei; Li, Peiyuan; Huang, Quanting; Guo, Yingyan; Zhong, Jiahui; Li, Futian; Wan, Jiaofeng; Overmans, Sebastian; Xia, Jianrong (Frontiers in Microbiology, Frontiers Media SA, 2021-10-14) [Article]
      Ocean acidification is recognized as a major anthropogenic perturbation of the modern ocean. While extensive studies have been carried out to explore the short-term physiological responses of phytoplankton to ocean acidification, little is known about their lipidomic responses after a long-term ocean acidification adaptation. Here we perform the lipidomic analysis of a marine diatom Phaeodactylum tricornutum following long-term (∼400 days) selection to ocean acidification conditions. We identified a total of 476 lipid metabolites in long-term high CO2 (i.e., ocean acidification condition) and low CO2 (i.e., ambient condition) selected P. tricornutum cells. Our results further show that long-term high CO2 selection triggered substantial changes in lipid metabolites by down- and up-regulating 33 and 42 lipid metabolites. While monogalactosyldiacylglycerol (MGDG) was significantly down-regulated in the long-term high CO2 selected conditions, the majority (∼80%) of phosphatidylglycerol (PG) was up-regulated. The tightly coupled regulations (positively or negatively correlated) of significantly regulated lipid metabolites suggest that the lipid remodeling is an organismal adaptation strategy of marine diatoms to ongoing ocean acidification. Since the composition and content of lipids are crucial for marine food quality, and these changes can be transferred to high trophic levels, our results highlight the importance of determining the long-term adaptation of lipids in marine producers in predicting the ecological consequences of climate change.
    • Extending the natural adaptive capacity of coral holobionts

      Voolstra, Christian R.; Suggett, David J.; Peixoto, Raquel S; Parkinson, John E.; Quigley, Kate M.; Silveira, Cynthia B.; Sweet, Michael; Muller, Erinn M.; Barshis, Daniel J.; Bourne, David G.; Aranda, Manuel (Nature Reviews Earth & Environment, Springer Science and Business Media LLC, 2021-10-12) [Article]
      Anthropogenic climate change and environmental degradation destroy coral reefs, the ecosystem services they provide, and the livelihoods of close to a billion people who depend on these services. Restoration approaches to increase the resilience of corals are therefore necessary to counter environmental pressures relevant to climate change projections. In this Review, we examine the natural processes that can increase the adaptive capacity of coral holobionts, with the aim of preserving ecosystem functioning under future ocean conditions. Current approaches that centre around restoring reef cover can be integrated with emerging approaches to enhance coral stress resilience and, thereby, allow reefs to regrow under a new set of environmental conditions. Emerging approaches such as standardized acute thermal stress assays, selective sexual propagation, coral probiotics, and environmental hardening could be feasible and scalable in the real world. However, they must follow decision-making criteria that consider the different reef, environmental, and ecological conditions. The implementation of adaptive interventions tailored around nature-based solutions will require standardized frameworks, appropriate ecological risk–benefit assessments, and analytical routines for consistent and effective utilization and global coordination.
    • A seaweed aquaculture imperative to meet global sustainability targets

      Duarte, Carlos M.; Bruhn, Annette; Krause-Jensen, Dorte (Nature Sustainability, Springer Science and Business Media LLC, 2021-10-07) [Article]
      Seaweed aquaculture accounts for 51.3% of global mariculture production and grows at 6.2% yr−1 (2000–2018). It delivers a broad range of ecosystem services, providing a source of food and natural products across a range of industries. It also offers a versatile, nature-based solution for climate change mitigation and adaptation and for counteracting eutrophication and biodiversity crisis. Here we offer the perspective that scaling up seaweed aquaculture as an emission capture and utilization technology, one supporting a circular bioeconomy, is an imperative to accommodate more than 9 billion people in 2050 while advancing across many of the United Nations Sustainable Development Goals.
    • An integrative study of Anemonia viridis (Forsskal, 1775) and Aiptasia couchii (Cocks, 1851) (Cnidaria: Anthozoa) from the North Adriatic Sea

      Arossa, Silvia; Cerrano, C.; Barucca, M.; Carducci, F.; Puce, S.; Di Camillo, C. G. (ZOOMORPHOLOGY, Springer Science and Business Media LLC, 2021-10-04) [Article]
      Although the biometric investigation of the cnidome represents an essential diagnostic feature to successfully identify cnidarian species, further efforts are needed to fully characterize eventual differences. Important model actiniarians, such Anemonia viridis and Aiptasia spp., are commonly used for scientific purposes; however, their identification is often difficult, and the description of their cnidome is, therefore, essential. To contribute to this necessity, specimens of Anemonia viridis and Aiptasia couchii from the North Adriatic Sea were collected to acquire data (i.e. length, width, size range, length/width ratio) about cnidae from different tissues (i.e. column, tentacles, actinopharynx, mesenteries, and acrorhagi/acontia). Four types of cnidae were observed in each species. A. viridis shows microbasic b-mastigophores, microbasic p-mastigophores, holotrichous isorhizas, and spirocysts, whereas A. couchii harbored basitrichs, microbasic p-mastigophore, microbasic p-amastigophore and spirocysts. Molecular and phylogenetic analyses were also performed using three mitochondrial markers to confirm the correct classification of the specimens here analysed..
    • The Simrad EK60 echosounder dataset from the Malaspina circumnavigation

      Irigoien, Xabier; Klevjer, Thor; Martinez, Udane; Boyra, Guillermo; Røstad, Anders; Wittmann, Astrid C.; Duarte, Carlos M.; Kaartvedt, Stein; Brierley, Andrew S.; Proud, Roland (Scientific Data, Springer Science and Business Media LLC, 2021-10-01) [Article]
      AbstractWe provide the raw acoustic data collected from the R/V Hesperides during the global Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz-14th July 2011, Cartagena) using a Simrad EK60 scientific echosounder operating at 38 and 120 kHz. The cruise was divided into seven legs: leg 1 (14th December 2010, Cádiz-13th January 2011, Rio de Janeiro), leg 2 (17th January 2011, Rio de Janeiro-6th February 2011, Cape Town), leg 3 (11th February 2011, Cape Town-13th March 2011, Perth), leg 4 (17th March 2011, Perth-30th March 2011, Sydney), leg 5 (16th April 2011, Auckland-8th May 2011, Honolulu), leg 6 (13th May 2011, Honolulu-10th June 2011, Cartagena de Indias) and leg 7 (19th June 2011, Cartagena de Indias-14th July 2011, Cartagena). The echosounder was calibrated at the start of the expedition and calibration parameters were updated in the data acquisition software (ER60) i.e., the logged raw data are calibrated. We also provide a data summary of the acoustic data in the form of post-processed products.
    • Oxidative stress in tissues of gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) juveniles exposed to ultraviolet-B radiation

      Alves, Ricardo; Agusti, Susana (Journal of Photochemistry and Photobiology, Elsevier BV, 2021-10-01) [Article]
      Ultraviolet-B (UVB) radiation generates reactive oxygen species (ROS), which damage DNA, proteins, and lipids in aquatic organisms, including fish. This study evaluated UVB-induced oxidative stress in several tissues of two marine teleosts, gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax). Juveniles of both species were exposed to four treatments simulating underwater UVB (no, low, moderate, and high UVB) doses for 6 weeks. Oxidative stress (the activities of several antioxidant enzymes (catalase, CAT; glutathione-S-transferase, GST; superoxide dismutase, SOD, and lipid peroxidation, LPO) were analyzed in the skin, liver, head kidney, gills, muscle, brain, intestine, spleen, and kidney samples obtained at increasing exposure times (3-43 days). UVB exposure induced significant lipid damage and antioxidant responses in several tissues, with the skin showing more pronounced effects in S. aurata than in D. labrax. In the skin of both species and in the liver of D. labrax, LPO levels significantly increased with increasing UVB intensity and exposure time. CAT activity was inhibited in both species (i.e., in liver, skin, head kidney, gills, spleen, and brain) of UVB exposed fish. SOD activity significantly decreased in the skin and head kidney of D. labrax; however, prolonged exposure time was required for significant effects in the skin and gills of S. aurata. GST activity reduced early in the skin of S. aurata, whereas significant effects were noted in the head kidney and brain at the end of experiment. An interactive effect between UVB intensity and exposure time was observed in the skin (seabream and seabass) and liver (seabass). Our results indicated that oxidative stress is induced in the skin as well as indirectly exposed tissues in S. aurata and D. labrax after UVB exposure at the subsurface of transparent seas.
    • Morphology and reproduction in the Hapalocarcinus marsupialis Stimpson, 1859 species complex (Decapoda: Brachyura: Cryptochiridae)

      Bähr, Susanne; Johnson, Magnus L.; Berumen, Michael L.; Hardenstine, Royale; Rich, Walter A.; van der Meij, Sancia E.T. (Journal of Crustacean Biology, Oxford University Press (OUP), 2021-09-30) [Article]
      Symbiotic relationships contribute considerably to the high biodiversity found on coral reefs. Coral-dwelling gall crabs (Cryptochiridae) represent a prime example of coral-associated invertebrates that exhibit obligate relationships with their host. The induction of a skeletal modification in the coral, used as a dwelling by the crab, is the most remarkable aspect of this close association. Here we examined Hapalocarcinus marsupialisStimpson, 1859, collected from Pocillopora and Stylophora corals in the Saudi Arabian Red Sea. Specimens were DNA barcoded, and five distinct clades were revealed, providing further evidence for the hypothesis that H. marsupialis is a species complex. Divergence (COI) between the clades ranged from 3.2 to 15.7%. The putative species were tested for differences in morphology and reproduction. Crabs were examined regarding morphometric characters (carapace length and width, pleon (abdomen), chelae, and growth patterns) and reproductive traits. The data were pooled and analysed by host genus and putative species, which revealed significant differences for most of the measured variables in female crabs. Specimens retrieved from Pocillopora were significantly larger (up to 49 %) and had higher fecundity than those inhabiting Stylophora. For reproductive output (RO) no differences at species- or host-genus level were detected. The average RO of ∼70% over all specimens is high compared to other brachyurans, supporting the assumption that symbiotic brachyurans invest more energy in reproduction than their free-living counterparts. Discrepancies with published data on growth and reproduction of Hapalocarcinus are discussed. Our results demonstrate the usefulness of morphometric traits and fecundity in separating the clades in the H. marsupialis complex, and prepare the ground for further morphometric studies on the genus and other symbiotic brachyurans. Moreover, it highlights the need to check for the presence of cryptic species when studying aspects of the biology of a species.
    • Larval dispersal and fishing pressure influence recruitment in a coral reef fishery

      Hamilton, Richard J.; Lozano-Cortés, Diego; Bode, Michael; Almany, Glenn R.; Harrison, Hugo B.; Pita, John; Saenz-Agudelo, Pablo; Gereniu, Collin; Waldie, Peter A.; Peterson, Nate; Choat, John Howard; Berumen, Michael L. (Journal of Applied Ecology, Wiley, 2021-09-28) [Article]
      Understanding larval connectivity patterns in exploited fishes is a fundamental prerequisite for developing effective management strategies and assessing the vulnerability of a fishery to recruitment overfishing and localised extinction. To date, however, researchers have not considered how regional variations in fishing pressure also influence recruitment. We used genetic parentage analyses and modelling to infer the dispersal patterns of bumphead parrotfish Bolbometopon muricatum larvae in the Kia fishing grounds, Isabel Province, Solomon Islands. We then extrapolated our Kia dispersal model to a regional scale by mapping the available nursery and adult habitat for B. muricatum in six regions in the western Solomon Islands, and estimated the relative abundance of adult B. muricatum populations in each of these regions based on available adult habitat and historical and current fishing pressure. Parentage analysis identified 67 juveniles that were the offspring of parents sampled in the Kia fishing grounds. A fitted larval dispersal kernel predicted that 50% of larvae settled within 30 km of their parents, and 95% settled within 85 km of their parents. After accounting for unsampled adults, our model predicted that 34% of recruitment to the Kia fishery was spawned locally. Extrapolating the spatial resolution of the model revealed that a high proportion of the larvae recruiting into the Kia fishing grounds came from nearby regions that had abundant adult populations. Other islands in the archipelago provided few recruits to the Kia fishing grounds, reflecting the greater distances to these islands and lower adult abundances in some regions. Synthesis and applications. This study shows how recruitment into a coral reef fishery is influenced by larval dispersal patterns and regional variations in historical fishing pressure. The scales of larval connectivity observed for bumphead parrotfish indicate that recruitment overfishing is unlikely if there are lightly exploited reefs up to 85 km away from a heavily fished region, and that small (<1 km2) marine-protected areas (MPAs) are insufficient to protect this species. We recommend greater efforts to understand the interactions between larval dispersal and gradients of fishing pressure, as this will enable the development of tailored fisheries management strategies.
    • Rank Change and Growth Within Social Hierarchies of the Orange Clownfish, Amphiprion Percula

      Fitzgerald, Lucy; Harrison, Hugo B; Coker, Darren James; Saenz-Agudelo, Pablo; Sriniva, Maya; Majoris, John E.; Einarsson, Lisa Boström; Pujol, Benoit; Bennett-Smith, Morgan; Thorrold, Simon R.; Planes, Serge; Jones, Geoffrey P.; Berumen, Michael L. (Research Square Platform LLC, 2021-09-21) [Preprint]
      Social hierarchies within groups define the distribution of resources and provide benefits that support the collective group or favor dominant members. The progression of individuals through social hierarchies is a valuable characteristic for quantifying population dynamics. On coral reefs, a number of small site-attached fish maintain size-based hierarchical communities where individuals queue through social ranks. The cost of waiting in a lower-ranked position is outweighed by the reduced risk of eviction and mortality. Clownfish exist in stable social groups with subordinate individuals queuing to be part of the dominant breeding pair. Site attachment to their host anemone, complex social interactions, and relatively low predation rates make them ideal model organisms to assess changes in group dynamics through time in their natural environment. Here, we investigate the rank changes, and isometric growth rates of individual orange clownfish, Amphiprion percula, from 247 naturally occurring social groups in Kimbe Island, Papua New Guinea (5°12’13.54” S, 150°22’32.69” E). We use DNA profiling to assign and track individuals over an eight-year time period in 2011 and 2019. Over half of the individuals survived alongside two or three members of their original social group, with twelve breeding pairs persisting over the study period. Half of the surviving individuals increased in rank and experienced double the growth rate of those that maintained their rank. Examining rank change over a long-term period in a wild fish population gives new insights and highlights the complexity and importance of rank and social hierarchy in communal site-attached reef fish.Subject Area: behavior, ecology, evolution
    • Environmental DNA reveals a multi-taxa biogeographic break across the Arabian Sea and Sea of Oman

      DiBattista, Joseph; Berumen, Michael L.; Priest, Mark A.; De Brauwer, Maarten; Coker, Darren James; Sinclair-Taylor, Tane H.; Hay, Amanda; Bruss, Gerd; Mansour, Shawky; Bunce, Michael; Goatley, Christopher H. R.; Power, Matthew; Marshell, Alyssa (Environmental DNA, Wiley, 2021-09-20) [Article]
      Environmental DNA (eDNA) is increasingly being used to assess community composition in marine ecosystems. Applying eDNA approaches across broad spatial scales now provide the potential to inform biogeographic analyses. However, to date, few studies have employed this technique to assess broad biogeographic patterns across multiple taxonomic groups. Here, we compare eDNA-derived communities of bony fishes and invertebrates, including corals and sponges, from 15 locations spanning the entire length of the Omani coast. This survey includes a variety of habitats, including coral and rocky reefs, and covers three distinct marine ecoregions. Our data support a known biogeographic break in fish communities between the north and the south of Oman; however, the eDNA data highlight that this faunal break is mostly reflected in schooling baitfish species (e.g., sardines and anchovies), whereas reef-associated fish communities appear more homogeneous along this coastline. Furthermore, our data provide indications that these biogeographic breaks also affect invertebrate communities, which includes corals, sponges, and broader eukaryotic groups. The observed community shifts were correlated with local environmental and anthropogenic differences characteristic of this coastline, particularly for the eDNA-derived bony fish communities. Overall, this study provides compelling support that eDNA sequencing and associated analyses may serve as powerful tools to detect community differences across biogeographic breaks and ecoregions, particularly in places where there is significant variation in oceanographic conditions or anthropogenic impacts.
    • Comprehensive analytical approaches reveal species-specific search strategies in sympatric apex predatory sharks

      Calich, Hannah J.; Rodríguez, J. P.; Eguíluz, V. M.; Hammerschlag, Neil; Pattiaratchi, Charitha; Duarte, Carlos M.; Sequeira, Ana M.M. (Ecography, Wiley, 2021-09-14) [Article]
      Animals follow specific movement patterns and search strategies to maximize encounters with essential resources (e.g. prey, favourable habitat) while minimizing exposures to suboptimal conditions (e.g. competitors, predators). While describing spatiotemporal patterns in animal movement from tracking data is common, understanding the associated search strategies employed continues to be a key challenge in ecology. Moreover, studies in marine ecology commonly focus on singular aspects of species' movements, however using multiple analytical approaches can further enable researchers to identify ecological phenomena and resolve fundamental ecological questions relating to movement. Here, we used a set of statistical physics-based methods to analyze satellite tracking data from three co-occurring apex predators (tiger, great hammerhead and bull sharks) that predominantly inhabit productive coastal regions of the northwest Atlantic Ocean and Gulf of Mexico. We analyzed data from 96 sharks and calculated a range of metrics, including each species' displacements, turning angles, dispersion, space-use and community-wide movement patterns to characterize each species' movements and identify potential search strategies. Our comprehensive approach revealed high interspecific variability in shark movement patterns and search strategies. Tiger sharks displayed near-random movements consistent with a Brownian strategy commonly associated with movements through resource-rich habitats. Great hammerheads showed a mixed-movement strategy including Brownian and resident-type movements, suggesting adaptation to widespread and localized high resource availability. Bull sharks followed a resident movement strategy with restricted movements indicating localized high resource availability. We hypothesize that the species-specific search strategies identified here may help foster the co-existence of these sympatric apex predators. Following this comprehensive approach provided novel insights into spatial ecology and assisted with identifying unique movement and search strategies. Similar future studies of animal movement will help characterize movement patterns and also enable the identification of search strategies to help elucidate the ecological drivers of movement and to understand species' responses to environmental change.
    • The time course of molecular acclimation to seawater in a euryhaline fish.

      Bonzi, Lucrezia C; Monroe, Alison; Lehmann, Robert; Berumen, Michael L.; Ravasi, Timothy; Schunter, Celia (Scientific reports, Springer Science and Business Media LLC, 2021-09-13) [Article]
      The Arabian pupfish, Aphanius dispar, is a euryhaline fish inhabiting both inland nearly-freshwater desert ponds and highly saline Red Sea coastal lagoons of the Arabian Peninsula. Desert ponds and coastal lagoons, located respectively upstream and at the mouths of dry riverbeds ("wadies"), have been found to potentially become connected during periods of intense rainfall, which could allow the fish to migrate between these different habitats. Flash floods would therefore flush Arabian pupfish out to sea, requiring a rapid acclimation to a greater than 40 ppt change in salinity. To investigate the molecular pathways of salinity acclimation during such events, a Red Sea coastal lagoon and a desert pond population were sampled, with the latter exposed to a rapid increase in water salinity. Changes in branchial gene expression were investigated via genome-wide transcriptome measurements over time from 6 h to 21 days. The two natural populations displayed basal differences in genes related to ion transport, osmoregulation and immune system functions. These mechanisms were also differentially regulated in seawater transferred fish, revealing their crucial role in long-term adaptation. Other processes were only transiently activated shortly after the salinity exposure, including cellular stress response mechanisms, such as molecular chaperone synthesis and apoptosis. Tissue remodelling processes were also identified as transient, but took place later in the timeline, suggesting their importance to long-term acclimation as they likely equip the fish with lasting adaptations to their new environment. The alterations in branchial functional pathways displayed by Arabian pupfish in response to salinity increases are diverse. These reveal a large toolkit of molecular processes important for adaptation to hyperosmolarity that allow for successful colonization to a wide variety of different habitats.
    • Symbiodinium microadriaticum (coral microalgal endosymbiont)

      Voolstra, Christian R.; Aranda, Manuel; Zhan, Ye; Dekker, Job (Trends in Genetics, Elsevier BV, 2021-09-11) [Article]
      Photosynthetic microalgae, from the family Symbiodiniaceae, engage in endosymbioses with marine invertebrates, including stony corals. More generally, dinoflagellates are ubiquitous protists and the main primary producers in the oceans. Despite their ecological and economic importance, their biology remains enigmatic. Here we assembled 94 chromosome-scale scaffolds of the ancestral Symbiodiniaceae species Symbiodinium microadriaticum. Contrary to the random order of genes typically found in eukaryotic cells, genes are enriched toward the ends of chromosomes in alternating unidirectional blocks that are sometimes enriched for genes of specific biological processes. These gene blocks are coexpressed and separated by structural boundaries where transcription converges. These structural domains, in turn, comprise the transcription-dependent basic building blocks of the chromosomes that fold as linear rods. Such a highly ordered structure linking gene orientation, transcription, and spatial organization of chromosomes is exceptional.
    • Testing angular velocity as a new metric for metabolic demands of slow-moving marine fauna: a case study with Giant spider conchs Lambis truncata

      Hopkins, Lloyd W.; Geraldi, Nathan; Pope, Edward C.; Holton, Mark D.; Lurgi, Miguel; Duarte, Carlos M.; Wilson, Rory P. (Animal Biotelemetry, Springer Science and Business Media LLC, 2021-09-07) [Article]
      Abstract Background Quantifying metabolic rate in free-living animals is invaluable in understanding the costs of behaviour and movement for individuals and communities. Dynamic body acceleration (DBA) metrics, such as vectoral DBA (VeDBA), are commonly used as proxies for the energy expenditure of movement but are of limited applicability for slow-moving species. It has recently been suggested that metrics based on angular velocity might be better suited to characterise their energetics. We investigated whether a novel metric—the ‘Rate of change of Rotational Movement (RocRM)’, calculated from the vectoral sum of change in the pitch, roll and yaw/heading axes over a given length of time, is a suitable proxy for energy expenditure. Results We found that RocRM can be used as an alternative energy expenditure proxy in a slow-moving benthic invertebrate. Eleven Giant spider conchs Lambis truncata (collected in the Red Sea) were instrumented with multiple channel (Daily Diary) tags and kept in sealed chambers for 5 h while their oxygen consumption, V̇O2, was measured. We found RocRM to be positively correlated with V̇O2, this relationship being affected by the time-step (i.e. the range of the calculated differential) of the RocRM. Time steps of 1, 5, 10 and 60 s yielded an explained variability of between 15 and 31%. The relationship between V̇O2 and VeDBA was not statistically significant, suggesting RocRM to provide more accurate estimations of metabolic rates in L. truncata. Conclusions RocRM proved to be a statistically significant predictor of V̇O2 where VeDBA did not, validating the approach of using angular-based metrics over dynamic movement-based ones for slower moving animals. Further work is required to validate the use of RocRM for other species, particularly in animals with minimally dynamic movement, to better understand energetic costs of whole ecosystems. Unexplained variability in the models might be a consequence of the methodology used, but also likely a result of conch activity that does not manifest in movement of the shell. Additionally, density plots of mean RocRM at each time-step suggest differences in movement scales, which may collectively be useful as a species fingerprint of movement going forward.
    • Integrating environmental variability to broaden the research on coral responses to future ocean conditions

      Ziegler, Maren; Anton Gamazo, Andrea; Klein, Shannon; Rädecker, Nils; Geraldi, Nathan; Schmidt-Roach, Sebastian; Saderne, Vincent; Mumby, Peter J.; Cziesielski, Maha Joana; Martin, Cecilia; Frölicher, Thomas L.; Pandolfi, John M.; Suggett, David J.; Aranda, Manuel; Duarte, Carlos M.; Voolstra, Christian R. (Global Change Biology, Wiley, 2021-09-03) [Article]
      Our understanding of the response of reef-building corals to changes in their physical environment is largely based on laboratory experiments, analysis of long-term field data, and model projections. Experimental data provide unique insights into how organisms respond to variation of environmental drivers. However, an assessment of how well experimental conditions cover the breadth of environmental conditions and variability where corals live successfully, is missing. Here, we compiled and analyzed a globally distributed dataset of in situ seasonal and diurnal variability of key environmental drivers (temperature, pCO2, and O2) critical for the growth and livelihood of reef-building corals. Using a meta-analysis approach, we compared the variability of environmental conditions assayed in coral experimental studies to current and projected conditions in their natural habitats. We found that annual temperature profiles projected for the end of the 21st century were characterized by distributional shifts in temperatures with warmer winters and longer warm periods in the summer, not just peak temperatures. Further, short-term hourly fluctuations of temperature and pCO2 may regularly expose corals to conditions beyond the projected average increases for the end of the 21st century. Coral reef sites varied in the degree of coupling between temperature, pCO2, and dissolved O2, which warrants site-specific, differentiated experimental approaches depending on the local hydrography and influence of biological processes on the carbonate system and O2 availability. Our analysis highlights that a large portion of the natural environmental variability at short and long time scales is underexplored in experimental designs, which may provide a path to extend our understanding on the response of corals to global climate change.
    • Sustainable and Eco-Friendly Coral Restoration through 3D Printing and Fabrication

      Albalawi, Hamed I.; Khan, Zainab N.; Valle-Pérez, Alexander U.; Kahin, Kowther M.; Hountondji, Maria; Alwazani, Hibatallah; Schmidt-Roach, Sebastian; Bilalis, Panagiotis; Aranda, Manuel; Duarte, Carlos M.; Hauser, Charlotte (ACS Sustainable Chemistry & Engineering, American Chemical Society (ACS), 2021-09-02) [Article]
      Coral reef degradation is a rising problem, driven by marine heatwaves, the spread of coral diseases, and human impact by overfishing and pollution. Our capacity to restore coral reefs lags behind in terms of scale, effectiveness, and cost-efficiency. While common restoration efforts rely on the formation of carbonate skeletons on structural frames for supported coral growth, this technique is a rate-limiting step in the growth of scleractinian corals. Reverse engineering and additive manufacturing technologies offer an innovative shift in approach from the use of concrete blocks and metal frames to sophisticated efforts that use scanned geometries of harvested corals to fabricate artificial coral skeletons for installation in coral gardens and reefs. Herein, we present an eco-friendly and sustainable approach for coral fabrication by merging three-dimensional (3D) scanning, 3D printing, and molding techniques. Our method, 3D CoraPrint, exploits the 3D printing technology to fabricate artificial natural-based coral skeletons, expediting the growth rate of live coral fragments and quickening the reef transplantation process while minimizing nursery costs. It allows for flexibility, customization, and fast return time with an enhanced level of accuracy, thus establishing an environmentally friendly, scalable model for coral fabrication to boost restorative efforts around the globe.
    • Diel dynamics of dissolved organic matter and heterotrophic prokaryotes reveal enhanced growth at the ocean's mesopelagic fish layer during daytime

      Moran, Xose Anxelu G.; García, Francisca C.; Røstad, Anders; Silva, Luis; Al-Otaibi, Najwa; Irigoien, Xabier; Calleja, Maria L. (Science of The Total Environment, Elsevier BV, 2021-09) [Article]
      Contrary to epipelagic waters, where biogeochemical processes closely follow the light and dark periods, little is known about diel cycles in the ocean's mesopelagic realm. Here, we monitored the dynamics of dissolved organic matter (DOM) and planktonic heterotrophic prokaryotes every 2 h for one day at 0 and 550 m (a depth occupied by vertically migrating fishes during light hours) in oligotrophic waters of the central Red Sea. We additionally performed predator-free seawater incubations of samples collected from the same site both at midnight and at noon. Comparable in situ variability in microbial biomass and dissolved organic carbon concentration suggests a diel supply of fresh DOM in both layers. The presence of fishes in the mesopelagic zone during daytime likely promoted a sustained, longer growth of larger prokaryotic cells. The specific growth rates were consistently higher in the noon experiments from both depths (surface: 0.34 vs. 0.18 d-1, mesopelagic: 0.16 vs. 0.09 d-1). Heterotrophic prokaryotes in the mesopelagic layer were also more efficient at converting extant DOM into new biomass. These results suggest that the ocean's twilight zone receives a consistent diurnal supply of labile DOM from diel vertical migrating fishes, enabling an unexpectedly active community of heterotrophic prokaryotes.
    • Host under epigenetic control: A novel perspective on the interaction between microorganisms and corals

      Barno, Adam R.; Villela, Helena D. M.; Aranda, Manuel; Thomas, Torsten; Peixoto, Raquel S (BioEssays, Wiley, 2021-08-31) [Article]
      Coral reefs have been challenged by the current rate and severity of environmental change that might outpace their ability to adapt and survive. Current research focuses on understanding how microbial communities and epigenetic changes separately affect phenotypes and gene expression of corals. Here, we provide the hypothesis that coral-associated microorganisms may directly or indirectly affect the coral's phenotypic response through the modulation of its epigenome. Homologs of ankyrin-repeat protein A and internalin B, which indirectly cause histone modifications in humans, as well as Rv1988 histone methyltransferase, and the DNA methyltransferases Rv2966c, Mhy1, Mhy2, and Mhy3 found in coral-associated bacteria indicate that there are potential host epigenome-modifying proteins in the coral microbiome. With the ideas presented here, we suggest that microbiome manipulation may be a means to alter a coral's epigenome, which could aid the current efforts to protect coral reefs.