ORCID Profile
0000-0002-1339-9546
Current Organisation
Hong Kong University of Science and Technology
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Springer Science and Business Media LLC
Date: 23-08-2013
Publisher: Elsevier BV
Date: 11-2017
Publisher: Springer Science and Business Media LLC
Date: 12-07-2011
Publisher: Wiley
Date: 09-2022
DOI: 10.1002/ECE3.9221
Abstract: Fish have one of the highest occurrences of in idual specialization in trophic strategies among Eukaryotes. Yet, few studies characterize this variation during trophic niche analysis, limiting our understanding of aquatic food web dynamics. Stable isotope analysis (SIA) with advanced Bayesian statistics is one way to incorporate this in idual trophic variation when quantifying niche size. However, studies using SIA to investigate trophodynamics have mostly focused on species‐ or guild‐level (i.e., assumed similar trophic strategy) analyses in settings where source isotopes are well‐resolved. These parameters are uncommon in an ecological context. Here, we use Stable Isotope Bayesian Ellipses in R (SIBER) to investigate cross‐guild trophodynamics of 11 reef fish species within an oceanic atoll. We compared two‐ ( δ 15 N and δ 13 C) versus three‐dimensional ( δ 15 N, δ 13 C, and δ 34 S) reconstructions of isotopic niche space for interpreting guild‐, species‐, and in idual‐level trophic strategies. Reef fish isotope compositions varied significantly among, but also within, guilds. In iduals of the same species did not cluster together based on their isotope values, suggesting within‐species specializations. Furthermore, while two‐dimensional isotopic niches helped differentiate reef fish resource use, niche overlap among species was exceptionally high. The addition of δ 34 S and the generation of three‐dimensional isotopic niches were needed to further characterize their isotopic niches and better evaluate potential trophic strategies. These data suggest that δ 34 S may reveal fluctuations in resource availability, which are not detectable using only δ 15 N and δ 13 C. We recommend that researchers include δ 34 S in future aquatic food web studies.
Publisher: Wiley
Date: 2013
Publisher: Wiley
Date: 16-01-2019
DOI: 10.1002/ECM.1339
Publisher: Public Library of Science (PLoS)
Date: 27-10-2010
Publisher: Wiley
Date: 04-02-2012
Publisher: Springer Science and Business Media LLC
Date: 07-07-2012
Publisher: Copernicus GmbH
Date: 28-08-2013
Abstract: Abstract. We investigated the biogeochemistry of low dissolved oxygen high-nitrate (LDOHN) layers forming against the backdrop of several interleaving regional water masses in the eastern Indian Ocean, off northwest Australia adjacent to Ningaloo Reef. These water masses, including the forming Leeuwin Current, have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. Our results indicate that LDOHN layers are formed from multiple subduction events of the Eastern Gyral Current beneath the Leeuwin Current (LC) the LC originates from both the Indonesian Throughflow and tropical Indian Ocean. Density differences of up to 0.025 kg m−3 between the Eastern Gyral Current and the Leeuwin Current produce sharp gradients that can trap high concentrations of particles (measured as low transmission) along the density interfaces. The oxidation of the trapped particulate matter results in local depletion of dissolved oxygen and regeneration of dissolved nitrate (nitrification). We document an associated increase in total dissolved carbon dioxide, which lowers the seawater pH by 0.04 units. Based on isotopic measurements (δ15N and δ18O) of dissolved nitrate, we determine that ~ 40–100% of the nitrate found in LDOHN layers is likely to originate from nitrogen fixation, and that, regionally, the importance of N-fixation in contributing to LDOHN layers is likely to be highest at the surface and offshore.
Publisher: Wiley
Date: 2005
Publisher: Frontiers Media SA
Date: 30-01-2020
Publisher: Wiley
Date: 06-2021
DOI: 10.1002/ECY.3324
Abstract: Variation among functionally similar species in their response to environmental stress buffers ecosystems from changing states. Functionally similar species may often be cryptic species representing evolutionarily distinct genetic lineages that are morphologically indistinguishable. However, the extent to which cryptic species differ in their response to stress, and could therefore provide a source of response ersity, remains unclear because they are often not identified or are assumed to be ecologically equivalent. Here, we uncover differences in the bleaching response between sympatric cryptic species of the common Indo‐Pacific coral, Pocillopora . In April 2019, prolonged ocean heating occurred at Moorea, French Polynesia. 72% of pocilloporid colonies bleached after 22 d of severe heating ( o C‐days) at 10 m depth on the north shore fore reef. Colony mortality ranged from 11% to 42% around the island four months after heating subsided. The majority (86%) of pocilloporids that died from bleaching belonged to a single haplotype, despite twelve haplotypes, representing at least five species, being s led. Mitochondrial (open reading frame) sequence variation was greater between the haplotypes that experienced mortality versus haplotypes that all survived than it was between nominal species that all survived. Colonies 30 cm in diameter were identified as the haplotype experiencing the most mortality, and in 1125 colonies that were not genetically identified, bleaching and mortality increased with colony size. Mortality did not increase with colony size within the haplotype suffering the highest mortality, suggesting that size‐dependent bleaching and mortality at the genus level was caused instead by differences among cryptic species. The relative abundance of haplotypes shifted between February and August, driven by declines in the same common haplotype for which mortality was estimated directly, at sites where heat accumulation was greatest, and where larger colony sizes occurred. The identification of morphologically indistinguishable species that differ in their response to thermal stress, but share a similar ecological function in terms of maintaining a coral‐dominated state, has important consequences for uncovering response ersity that drives resilience, especially in systems with low or declining functional ersity.
Publisher: Public Library of Science (PLoS)
Date: 18-11-2011
Publisher: Wiley
Date: 07-2021
DOI: 10.1002/BES2.1885
Publisher: Springer Science and Business Media LLC
Date: 13-05-2021
Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
Date: 2019
Publisher: The Oceanography Society
Date: 09-2013
Publisher: Frontiers Media SA
Date: 24-03-2022
DOI: 10.3389/FMARS.2022.821478
Abstract: The application of stable isotope analysis (SIA) is increasing in elasmobranch trophic ecology, but inconsistency remains in terms of the tissue pre-treatment methods chosen to remove biases introduced by lipids and urea. SIA of a range of non-lethally extracted tissues from a erse group of elasmobranchs, including mesopredators, is increasing, yet most studies assume that isotope biases from lipid and urea are the same across tissues and species. To determine tissue- and species-specific isotope biases across treatment methods, three tissues and their components [muscle, fin, and blood separated into plasma and red blood cells (RBC)] were non-lethally extracted from three species of mesopredatory elasmobranchs and subjected to one of three treatment methods: (1) deionized water rinse [DW], (2) chloroform/methanol lipid extraction [LE], or (3) deionized water followed by chloroform/methanol [DW+LE]. In muscle δ 13 C, all treatments displayed minimal variation (∼ 0‰) but large increases in δ 15 N (∼ 1‰) indicated urea removal. Fin δ 13 C values decreased with DW but increased with LE and DW+LE, whilst all treatments increased fin δ 15 N (∼ 0.5‰), suggesting removal of both lipid and urea. Plasma δ 13 C and δ 15 N displayed high in idual variation large decreases in δ 13 C (∼−0.8‰) across all treatments, but particularly DW, suggested the removal of 13 C-enriched compounds while a small increase in δ 15 N (∼ 0.2‰) suggested minimal urea removal. In RBC, all treatments showed small δ 13 C declines (∼−0.5‰), with no difference in δ 15 N, suggesting minimal removal of 13 C-enriched compounds and urea. For muscle and fin, DW+LE is the most appropriate treatment to standardize δ 13 C and δ 15 N consistently across in iduals and tissues. The large in idual variation in treatment effects on plasma suggests it is unsuitable for current treatment methods. Consistent treatment effects for RBC allow for DW+LE standardization, however, broader species-specific effects are unknown. The importance of treatment choice for accurately estimating prey contributions to elasmobranch diet was highlighted using Bayesian stable isotope mixing model comparisons, with prey contributions varying significantly among treatments. This variability suggests that ecological inferences from elasmobranch tissue SIA are not robust to different treatment methods. It is recommended that studies employ standardized corrections using a combined DW+LE treatment where applicable.
Publisher: Frontiers Media SA
Date: 27-08-2018
Publisher: CRC Press
Date: 16-11-2022
Publisher: Springer Science and Business Media LLC
Date: 18-01-2018
DOI: 10.1038/S41559-017-0432-Z
Abstract: Sharks are a erse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain in iduals that forage within additional isotopically erse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.
Publisher: Frontiers Media SA
Date: 05-10-2022
Abstract: Reef fish may switch feeding strategies due to fluctuations in resource availability or through ontogeny. A number of studies have explored these trophodynamics using carbon (δ 13 C) and nitrogen (δ 15 N) stable isotopes, but additional tracers such as sulfur isotopes (δ 34 S) show strong potential in systems, where δ 13 C and δ 15 N results are ambiguous. We tested the utility of adding δ 34 S to conventional δ 13 C and δ 15 N analysis to detect seasonal and body size changes in resource use of two planktivorous damselfish, Dascyllus reticulatus and Dascyllus trimaculatus across the Puerto Galera embayment in the Philippines. We analyzed stable isotope ratios (δ 13 C, δ 15 N, and δ 34 S) in multiple fish tissues (liver, eye, and muscle) to represent different dietary time frames. We then compared fish tissue isotopes against particulate organic matter (POM) (δ 13 C and δ 15 N) and POM suspension feeder (the tunicate Polycarpa aurata : δ 13 C, δ 15 N, and δ 34 S) across the same sites. There were size-based and seasonal differences in damselfish resource use, the latter of which was most pronounced in the fast-turnover liver. Small fish (& mm) demonstrated significant seasonality, appearing to switch their resource use between the rainy season and the dry season, while there was no seasonal variation in larger fish (& mm). This suggests that smaller fish across the embayment employ an opportunistic feeding strategy to take advantage of fluctuating resource availability, while larger fish exhibits more consistent resource use. Isotope ratios of tunicates and POM further confirmed strong seasonality in this system and a lack of a spatial isotopic gradient. δ 15 N did not seem to contribute to consumer resource use patterns, while by contrast, δ 34 S fluctuated significantly between s ling periods and was crucial for demonstrating seasonality in resource use. We recommend including δ 34 S when attempting to disentangle seasonal differences in resource use in aquatic food webs using stable isotopes.
Publisher: Springer Science and Business Media LLC
Date: 06-01-2023
DOI: 10.1038/S41467-022-35550-5
Abstract: The severity of marine heatwaves (MHWs) that are increasingly impacting ocean ecosystems, including vulnerable coral reefs, has primarily been assessed using remotely sensed sea-surface temperatures (SSTs), without information relevant to heating across ecosystem depths. Here, using a rare combination of SST, high-resolution in-situ temperatures, and sea level anomalies observed over 15 years near Moorea, French Polynesia, we document subsurface MHWs that have been paradoxical in comparison to SST metrics and associated with unexpected coral bleaching across depths. Variations in the depth range and severity of MHWs was driven by mesoscale (10s to 100s of km) eddies that altered sea levels and thermocline depths and decreased (2007, 2017 and 2019) or increased (2012, 2015, 2016) internal-wave cooling. Pronounced eddy-induced reductions in internal waves during early 2019 contributed to a prolonged subsurface MHW and unexpectedly severe coral bleaching, with subsequent mortality offsetting almost a decade of coral recovery. Variability in mesoscale eddy fields, and thus thermocline depths, is expected to increase with climate change, which, along with strengthening and deepening stratification, could increase the occurrence of subsurface MHWs over ecosystems historically insulated from surface ocean heating by the cooling effects of internal waves.
Publisher: Springer Science and Business Media LLC
Date: 18-11-2019
Publisher: Inter-Research Science Center
Date: 29-04-2010
DOI: 10.3354/MEPS08508
No related grants have been discovered for Alex Wyatt.