Alex S.J. Wyatt

Hong Kong University of Science and Technology | UST · Department of Ocean Science

Seasonal observations of phytoplankton uptake at Ningaloo Reef, Western Australia, reinforce the importance of particulate organic nitrogen (PON) and carbon (POC) in reef nutrient budgets and identify wave action and the dynamics of regional currents (over a range of temporal and spatial scales) as important factors determining plankton supply to t...

In contrast to trophodynamic variations, the marked zonation in physical and biological processes across coral reefs and the concomitant changes in habitat and community structure are well documented. In this study, we demonstrate consistent spatial changes in the community-level trophodynamics of 46 species of fish across the fringing Ningaloo Ree...

Intra‐species variability in foraging strategies may be common, which has significant implications for efforts to understand and manage enigmatic species like the whale shark Rhincodon typus. The ecological relevance of differences in tissue isotopes within and between individuals in the context of foraging however depends on understanding tissue t...

Coral reefs are among the most species-rich, productive and economically valuable ecosystems on Earth but increasingly frequent pantropical coral bleaching events are threatening their persistence on a global scale. The 2015–2016 El Niño led to the hottest sea surface temperatures on record and widespread bleaching of shallow-water corals. However,...

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, a...

The ongoing urbanisation of coastlines around the globe greatly impacts biodiversity, including coastal marine fishes. In many places, baseline data on fish communities are inadequate for understanding and managing the ecological impacts of this urbanisation. Here, we document spatiotemporal patterns in fish diversity (at genus level) across an est...

The ongoing urbanisation of coastlines around the globe jeopardises biodiversity, including coastal marine fishes. In many places, baseline data on fish communities are inadequate for understanding the ecological and conservation impacts of this urbanisation. Here, we document spatiotemporal patterns in fish diversity (at genus level) across an est...

We collated hundreds of temperature time series from around the world’s oceans recorded at a frequency of 1 hour or less. Using these data, we tested for patterns in temperature variability across climate regions. Contrary to the climate variability hypothesis, which states that the temperature variability is highest in temperate regions and lowest...

Coral reef ecosystems are exceptionally complex with a myriad of trophic pathways and consumer relationships. The application of stable isotopes (SIs) offers numerous advantages over traditional methods towards understanding these intricate systems. We summarize current knowledge derived from the rapidly increasing SI literature base and identify p...

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 (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes, but additional tracers such as sulfur isotopes (δ³⁴S) show strong potential in systems, where δ¹³C and δ¹⁵N results are ambiguous. W...

Fish have one of the highest occurrences of individual 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 individual t...

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 diverse group of elasmobranchs, including mesopredators, is increasing,...

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 respo...

Cryptic species that are morphologically similar co-occur because either the rate of competitive exclusion is very slow, or because they are not, in fact, ecologically similar. The processes that maintain cryptic local diversity may, therefore, be particularly subtle and difficult to identify. Here, we uncover differences among several cryptic spec...

We sought to resolve the extent, variability, and magnitude of productivity enrichment around a high tropical island consistent with the phenomenon of an Island Mass Effect (IME). Key biogeochemical constituents and physical oceanographic parameters were measured offshore over the upper 500 m from July 27 to August 7, 2014 around the Society Island...

Populations of marine organisms on coral reef islands (CRI) are connected in space and time by seawater that transports propagules of plants, animals, and algae. Yet, despite this reality, it is often assumed that routine replenishment of populations of marine organisms on CRI is supported by locally-sourced propagules (hereafter, larvae). Followin...

Sharks are a diverse 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 fi...

Compound-specific isotopic analysis of amino acids (CSIA-AA) has emerged in the last decade as a powerful approach for tracing the origins and fate of nitrogen in ecological and biogeochemical studies. This approach is based on the empirical observation that source amino acids (AAs)s (i.e., phenylalanine), fractionate ¹⁵N very little (< 0.5‰) durin...

This study proposes an improvement to the method for evaluating suspended sediment (SS) transport from different regions of a catchment to the downstream area using X-ray fluorescence (XRF) analysis. The target area, the Oromushi River basin in Hokkaido, has SS yields among the highest in Japan due to the predominance of soils originated from volca...

The Moorea Coral Reef Long Term Ecological Research project funded by the US National Science Foundation includes multidisciplinary studies of physical processes driving ecological dynamics across the fringing reef, back reef, and fore reef habitats of Moorea, French Polynesia. A network of oceanographic moorings and a variety of other approaches h...

Dissolved organic nitrogen (DON) potentially plays a major role in sustaining the high productivity and biological diversity of coral reefs. However, data are scarce regarding sources and sinks of DON. This study, for the first time, determined the 15 N isotopic composition of total dissolved nitrogen (d 15 N TDN), reflecting the isotopic sig-natur...

We investigate the biogeochemistry of Low Dissolved Oxygen High Nitrate 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 functio...

We investigate the biogeochemistry of Low Dissolved Oxygen High Nitrate 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 functio...

We examined spatial and temporal variations in particulate organic matter (POM) dynamics over a fringing coral reef (Ningaloo Reef) in Western Australia during the austral autumn and spring. Total POM concentrations generally did not differ between seasons or reef zones, but the composition of POM, in terms of carbon isotope ratios (δ13C-POM), carb...

Nitrate and nitrite (NO x) and phosphate (PO 4) dynamics over Ningaloo Reef, Western Australia, are shown to depend on oceanographic forcing of coupled mass transfer limited (MTL) gross uptake and gross release from remineralized oceanic particulate organic matter (POM). Estimates of gross release rates increased significantly with increasing POM u...

Pairwise changes in concentrations of DOC and oxygen through time in the Light and Dark phases of incubation for each treatment. Each line represents an individual replicate incubation vessel. (TIF)

Individual replicate bacterial growth curves for each benthic producer treatment and controls in the dark dilution cultures. Ambient backreef bacterioplankton density ranges over the course of the experiments are highlighted with a gray band. (TIF)

Light availability and temperature regime in situ at the Moorea backreef location and in incubation beakers during daylight incubations. (TIF)

Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates...

We examined the importance of picoplankton and virioplankton to reef trophodynamics at Ningaloo Reef, (north-western Australia), in May and November 2008. Picophytoplankton (Prochlorococcus, Synechococcus and picoeukaryotes), bacterioplankton (inclusive of bacteria and Archaea), virioplankton and chlorophyll a (Chl a) were measured at five stations...

Interpretation of stable isotope ratios of carbon and nitrogen (δ(13)C and δ(15)N) is generally based on the assumption that with each trophic level there is a constant enrichment in the heavier isotope, leading to diet-tissue discrimination factors of 3.4‰ for (15)N (ΔN) and ∼0.5‰ for (13)C (ΔC). Diet-tissue discrimination factors determined from...

An entire-area survey conducted during spring tide in Tokyo Bay on November 21st, 2002 revealed a vertically well-mixed density at the bay mouth. An Acoustic Doppler Current Profiler (ADCP) was deployed to a depth of 40 m at a location 10 km landward from the mixing. The ADCP survey results indicated suppression of estuarine circulation during the...

This paper describes the occurrence of the front around the head of Tokyo Bay. Salinity, temperature and ADCP measurements were performed in Tokyo Bay during a spring tide on 21st November 2002. It was revealed the estuary circulation was suppressed and the down-welling appeared as a result of the front during the spring tide. Numerical computation...

The presence and impacts of non-indigenous species (NIS) in marine areas of high conservation or World Heritage significance have rarely been examined. Case studies worldwide suggest that the potential exists for the introduction of NIS to significantly impact conservation values in regions conserved for the uniqueness and diversity of native assem...

Abstract The potential pollution of tropical marine environments,bordering coastlines as a result of population growth and development,is widely acknowledged. Coastal marine environments and resources in developing nations are particularly susceptible, being closest to concentrations of population and industry, being areas popular for recreation, a...