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  • 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.
  • The Importance of Larval Stages for Considering Crab Microbiomes as a Paradigm for the Evolution of Terrestrialization

    Wale, Matthew; Daffonchio, Daniele; Fusi, Marco; Marasco, Ramona; Garuglieri, Elisa; Diele, Karen (Frontiers in Microbiology, Frontiers Media SA, 2021-10-15) [Article]
    The transition from an aquatic to a terrestrial lifestyle has evolved multiple times, and in numerous different phyla, in earth’s history. In many crab species, this process is still underway (Bliss and Mantel, 1968), providing a unique opportunity to study the evolution of terrestrialization, as well as the role of associated microbiomes during this process (Cannicci et al., 2020). Recently, Cannicci et al. (2020) reported on the potential importance of microbiomes in the transition of crabs, formally wholly aquatic species, to life, fully or in part, in terrestrial environments. The authors argue that symbiotic bacteria, such as those of gill and gut microbiomes, may play a key role in easing this transition, by helping crabs to overcome physiological and morphological challenges associated with conquering the terrestrial environment, such as impaired respiration and osmotic regulation, and a new, often primary plant-based low nitrogen diet. Here we focus on the microbiomes of crab larvae and their potential role for the evolution of terrestrialization. Crabs that are transitioning to life on land fall into two broad categories: terrestrial species that spend their whole adult life (except for larval release) on land independent of tidal inundation or freshwater bodies, and semi-terrestrial species that spend their adult life on land but are dependent on tidal inundation or freshwater (Burggren and McMahon, 1988; Anger, 1995). Many marine organisms form symbiotic relationships with microorganisms to aid life in extreme environments (Sogin et al., 2020). In line with the hologenome theory, this suggests that host-microbe interactions play an important role in an organism’s evolution, where the genes of both the host and its microbes co-evolve in the collective “holobiont” (Zilber-Rosenberg and Rosenberg, 2008), potentially allowing the colonization of formerly hostile environments (Bang et al., 2018). Microbial symbionts, as individual species or in mixed-species assemblages, are present in many crustaceans, such as the marine isopod Idotea balthica (diet-specific gut microbiomes, Mattila et al., 2014), the intertidal brachyuran crab Eriocheir sinensis (gill and gut microbiomes, Zhang et al., 2016), and the freshwater signal crayfish Pacifastacus leniusculus (intestinal bacteria, Hernández-Pérez et al., 2021). Given that microbial assemblages are often specific to certain organs of their hosts (Chomicki et al., 2020), symbioses have likely evolved in support of a specific function. The microbial assemblages associated with the guts of semi-terrestrial crabs have been proposed to aid in the adaptation of a low nitrogen, herbivorous diet during terrestrialization (Bui and Lee, 2015), like microbial assemblages of other aquatic invertebrates, e.g., isopods, where they enable the digestion of cellulose (Zimmer et al., 2002; O’Connor et al., 2014). The bacteria specifically associated with crab gills (Zhang et al., 2016, 2017) may facilitate ammonia excretion (Weihrauch et al., 2004), utilize gaseous CO2 (Morris, 2001), and buffer exposure to oxygen, which occurs at a concentration 30 times higher (Hsia et al., 2013) in the terrestrial compared to the marine environment where the host organism evolved. The microbiomes of both gut and gills could therefore provide terrestrial and semi-terrestrial crabs (here collectively called semi-/terrestrial) with means to cope with life in marine as well as in terrestrial environments. Whilst the presence of microbiomes and their role in buffering the stresses imposed on crabs by terrestrialization is beginning to be discussed (Bui and Lee, 2015; Cannicci et al., 2020), there are many unknowns. For example, the mode of bacterial acquisition, bacterial diversity, topological association, and the precise functions of their organ-specific microbial assemblages are still poorly understood, both for adult semi-/terrestrial crabs and their early life stages. Most semi-/terrestrial crab species, like their aquatic counterparts, have a biphasic life cycle including fully aquatic larvae, via which they transition to semi-/terrestrial juvenile/adult life (Anger, 1995; Hartnoll etal.,2014).Understanding microbial colonization of the larvae would likely provide critical insights into how these crabs have been able to move from water to land, and whether the bacteria themselves facilitate this transition.
  • 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.
  • Genomic and metabolic adaptations of biofilms to ecological windows of opportunities in glacier-fed streams

    Busi, Susheel Bhanu; Bourquin, Massimo; Fodelianakis, Stylianos; Michoud, Gregoire; Kohler, Tyler J; Peter, Hannes; Pramateftaki, Paraskevi; Styllas, Michail; Tolosano, Matteo; De Staercke, Vincent; Schon, Martina; de Nies, Laura; Marasco, Ramona; Daffonchio, Daniele; Ezzat, Leila; Wilmes, Paul; Battin, Tom J (Cold Spring Harbor Laboratory, 2021-10-08) [Preprint]
    Microorganisms dominate life in cryospheric ecosystems. In glacier-fed streams (GFSs), ecological windows of opportunities allow complex microbial biofilms to develop and transiently form the basis of the food web, thereby controlling key ecosystem processes. Here, using high-resolution metagenomics, we unravel strategies that allow biofilms to seize this opportunity in an ecosystem otherwise characterized by harsh environmental conditions. We found a diverse microbiome spanning the entire tree of life and including a rich virome. Various and co-existing energy acquisition pathways point to diverse niches and the simultaneous exploitation of available resources, likely fostering the establishment of complex biofilms in GFSs during windows of opportunity. The wide occurrence of rhodopsins across metagenome-assembled genomes (MAGs), besides chlorophyll, highlights the role of solar energy capture in these biofilms. Concomitantly, internal carbon and nutrient cycling between photoautotrophs and heterotrophs may help overcome constraints imposed by the high oligotrophy in GFSs. MAGs also revealed mechanisms potentially protecting bacteria against low temperatures and high UV-radiation. The selective pressure of the GFS environment is further highlighted by the phylogenomic analysis, differentiating the representatives of the genus Polaromonas, an important component of the GFS microbiome, from those found in other ecosystems. Our findings reveal key genomic underpinnings of adaptive traits that contribute to the success of complex biofilms to exploit environmental opportunities in GFSs, now rapidly changing owing to global warming.
  • 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.
  • Contribution of Tamarix aphylla to soil organic matter evolution in a natural semi-desert area in Tunisia

    Tambone, Fulvia; Trombino, Luca; Masseroli, Anna; Zilio, Massimo; Pepè Sciarria, Tommy; Daffonchio, Daniele; Borin, Sara; Marasco, Ramona; Cherif, Ameur; Adani, Fabrizio (Journal of Arid Environments, Elsevier BV, 2021-10-06) [Article]
    A soil, classified as Arenosol (Eutri-Aridic Arenosol (Calcaric)), located in Neffatia (Tunisia) and populated by the shrub tamarisk (Tamarix aphylla), was studied to assess how the litter deriving from tamarisk can affect its characteristics. Several parameters were considered: particle size distributions (PSD), pH, cation exchange capacity (CEC), total CaCO3 content, total nitrogen (TKN), phosphorus and total organic carbon (TOC). Down the soil profile the pH increased from 7.83 to 8.32 as a probable consequence of salts accumulation deriving from the mineralization of the organic matter and the limited leaching due to low rainfall. As expected, TOC and TKN decreased, from the top downwards, and the two parameters were well correlated (TOC vs TKN: R2 = 0.98; p < 0.05; n = 3). CEC assumed progressively lower values reflecting the decreasing organic matter content (CEC vs TOC: R2 = 0.93; p < 0.05; n = 3). PSD showed that the presence of roots influenced the quantity of fine particles down the profile and the PSD cumulative curves were indicative of an aeolian origin for the soil parent material, confirming the hypothesis that tamarisk interacts with the environment, trapping sediment and forming the so-called phytogenic dunes. By chemical and spectroscopic analyses, it was possible to assess that tamarisk plant residues directly contributed to the soil organic matter (SOM) accumulation and characteristics. Stable SOM (ligno-humic fraction) closely resembles that of the plant (leaves and stems) and is chemically lacking in the more easily degradable organic components such as fats, hemicellulose, cellulose and proteins. 13C CPMAS NMR spectroscopy showed that the so-called soil ligno-humic fraction consists of aromatic molecules such as tannins, and aliphatic carbon (i.e. cutins and suberins) already present in the plant and preserved by mineralization processes because they are the most resistant to biological degradation.
  • 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), 2021-10-05) [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.
  • 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.
  • 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, 2021-09-14) [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.
  • Aridity modulates belowground bacterial community dynamics in olive tree

    Marasco, Ramona; Fusi, Marco; ROLLI, Eleonora; Ettoumi, Besma; Tambone, Fulvia; Borin, Sara; Ouzari, Hadda-Imene; Boudabous, Abdellatif; Sorlini, Claudia; Cherif, Ameur; Adani, Fabrizio; Daffonchio, Daniele (Environmental Microbiology, Wiley, 2021-09-07) [Article]
    Aridity negatively affects the diversity and abundance of edaphic microbial communities and their multiple ecosystem services, ultimately impacting vegetation productivity and biotic interactions. Investigation about how plant-associated microbial communities respond to increasing aridity is of particular importance, especially in light of the global climate change predictions. To assess the effect of aridity on plant associated bacterial communities, we investigated the diversity and co-occurrence of bacteria associated with the bulk soil and the root system of olive trees cultivated in orchards located in higher, middle and lower arid regions of Tunisia. The results indicated that the selective process mediated by the plant root system is amplified with the increment of aridity, defining distinct bacterial communities, dominated by aridity-winner and aridity-loser bacteria negatively and positively correlate with increasing annual rainfall, respectively. Aridity regulated also the co-occurrence interactions among bacteria by determining specific modules enriched with one of the two categories (aridity-winners or aridity-losers), which included bacteria with multiple PGP functions against aridity. Our findings provide new insights into the process of bacterial assembly and interactions with the host plant in response to aridity, contributing to understand how the increasing aridity predicted by climate changes may affect the resilience of the plant holobiont.
  • 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.
  • 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.
  • Different resiliencies in coral communities over ecological and geological time scales in American Samoa

    Birkeland, C; Green, Alison Lesley; Lawrence, A; Coward, G; Vaeoso, M; Fenner, D (Marine Ecology Progress Series, Inter-Research Science Center, 2021-09-02) [Article]
    In 1917, Alfred Mayor surveyed a 270 m transect on a reef flat on American Samoa. Eleven surveys were conducted on the transect from 1917 to 2019. The coral community on the reef crest was resilient over the century, occasionally being seriously damaged but always recovering rapidly. In contrast, the originally most dense coral community on the reef flat has been steadily deteriorating throughout the century. Resilience of coral communities in regions of high wave energy on the reef crests was associated with the important binding function of the crustose coralline alga (CCA) Porolithon onkodes. Successful coral recruits were found on CCA 94% of the time, yet living coral cover correlated negatively with CCA cover as they became alternative winners in competition. Mayor drilled a core from the transect on the surface to the basalt base of the reef 48 m below. Communities on Aua reef were dominated by scleractinians through the Holocene, while cores on another transect 2 km away showed the reef was occupied by alcyonaceans of the genus Sinularia, which built the massive reef with spiculite to the basalt base 37 m below. Despite periods of sea levels rising 9 to 15 times the rate of reef accretion, the reefs never drowned. The consistency of scleractinians on Aua reef and Sinularia on Utulei Reef 2 km away during the Holocene was because the shape of the bay allowed more water motion on Aua reef. After 10700 yr of reef building by octocorals, coastal construction terminated this spiculite-reef development.
  • 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.

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