Roger Cropp

Coral reefs are important regional sources of biogenic sulfur to the tropical marine atmosphere, through stress-induced emissions of dimethylsulfide (DMS). Recent estimates suggest that the Great Barrier Reef (GBR), Australia emits 0.02-0.05 Tg yr⁻¹ of DMS (equivalent to 0.010-0.026 Tg yr⁻¹ S), with potential implications for local aerosol-cloud pr...

Marine dimethylsulfide (DMS) is an important source of natural sulfur to the atmosphere, with potential implications for the Earth’s radiative balance. Coral reefs are important regional sources of DMS, yet their contribution is not accounted for in global DMS climatologies or in model simulations. This study accounts for coral-reef-derived DMS and...

We develop a novel eco-evolutionary modelling framework and demonstrate its efficacy by simulating the evolution of trait distributions in predator and prey populations. The eco-evolutionary modelling framework assumes that population traits have beta distributions and defines canonical equations for the dynamics of each total population size, the...

Migratory bird species may serve as vectors of contaminants to Antarctica through the local deposition of guano, egg abandonment, or mortality. To further investigate this chemical input pathway, we examined the contaminant burdens and profiles of the migratory South polar skua (Catharacta maccormicki) and compared them to the endemic Adélie pengui...

We develop new equations for the eco-evolutionary dynamics of populations and their traits. These equations resolve the change in the phenotypic differentiation within a population, which better estimates how the variance of the trait distribution changes. We note that traits may be bounded, assume they may be described by beta distributions with s...

Eco-evolutionary models commonly assume that traits are normally distributed in a population, and that the trait bounds do not influence the adaptation of traits. However, recent empirical evidence suggests that at least some traits are not normally distributed, and there is theoretical support for the view that trait bounds can be fundamental to t...

Biogenic emissions of dimethylsulfide (DMS) are an important source of sulfur to the atmosphere, with implications for aerosol formation and cloud albedo over the ocean. Natural aerosol sources constitute the largest uncertainty in estimates of aerosol radiative forcing and climate and thus, an improved understanding of DMS sources is needed. Coral...

We review the evidence for bio-regulation by coral reefs of local climate through stress-induced emissions of aerosol precursors, such as dimethylsulfide. This is an issue that goes to the core of the coral ecosystem’s ability to maintain homeostasis in the face of increasing climate change impacts and other anthropogenic pressures. We examine this...

Coral reef systems are under increasing pressure to adapt to rapidly varying environmental conditions, in particular increasing ocean temperatures. A question of major concern is whether coral reefs can adapt to and survive the predicted increases in global temperatures over the remainder of this century. A simple model of a coral reef ecosystem is...

Global climate change and the impacts of ocean warming, ocean acidification and declining water quality are adversely affecting coral-reef ecosystems. This is of great concern, as coral reefs provide numerous ecosystem, economic and social services. Corals are also recognised as being amongst the strongest individual sources of natural atmospheric...

Variability in atmospheric dimethylsulfide (DMSa) and the potential influence on atmospheric aerosols was investigated at Heron Island in the southern Great Barrier Reef (GBR), Australia. This work compiles previously published DMSa data (reported in Swan, Jones, Deschaseaux, & Eyre, 2017, https://doi.org/10.5194/bg‐14‐229‐2017), with additional su...

Ecosystems and food webs are structured into trophic levels of who eats whom. Species that occupy higher trophic levels have less available energy and higher energetic costs than species at lower trophic levels. So why do higher trophic levels exist? What processes generate new trophic levels? We consider a heuristic eco-evolutionary model based on...

We consider eco-evolutionary processes that include natural bounds on adaptive trait distributions. We implement ecological axioms, that a population grows if it is replete with resources, and doesn’t grow if it has none. These axioms produce natural bounds on the trait means that suggest that the assumption of gamma-distributed traits, where the t...

The original version of this article unfortunately contains an incorrect panel (b) in Fig. 1 introduced during the production process.

Coral reefs are being threatened by global climate change, with ocean warming and acidification, compounded by declining water quality in many coastal systems, adversely affecting coral health and cover. This is of great concern as coral reefs provide numerous ecosystem, economic and social services. Corals are also recognized as being amongst the...

Mutualist interactions are thought to be ubiquitous, spanning all levels of biological organisation, and involving most species on Earth. However, in contrast to population interactions such as competition and predation, a comprehensive and succinct theoretical explanation of mutualism has proved elusive. We use a new modelling framework that repre...

A plankton eco-evolutionary model with an alga that has the metabolic pathways to allow it to function as an autotroph or heterotroph is considered. Ecological constraints dictate that the traits that describe the feeding preferences and abilities of the alga naturally have bounded distributions. The trait distributions are then non-normal, and evo...

The concept of a carrying capacity of an environment for a population has been an effective way of introducing a connection between populations and their environment. This approach has been particularly effective in heuristic Lotka–Volterra models of competition and predation that provide a basis for theoretical considerations of population interac...

We investigate the influence of mixotrophy on the dynamical properties of a six-population model of a three–trophic level Southern Ocean ecosystem. We find that including mixotrophic interactions between the lowest trophic level populations can significantly influence the dynamics of the highest trophic level populations, and in extreme cases lead...

Hexachlorobenzene (HCB) is an example of a persistent organic pollutant (POP) that is relatively abundant and widespread in near shore Antarctic marine environments. By definition, POPs may distribute with an ecosystem, bioaccumulating and potentially reaching hazardous levels in some organisms. Modelling approaches may provide insight into this be...

Concentrations of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS), and DMS flux are reported for the Great Barrier Reef (GBR), Great Barrier Reef Lagoon (GBRL), and Coral Sea. Generally higher concentrations of dimethylsulfoniopropionate and DMS occurred in coral reef waters, compared with GBRL concentrations. DMS flux from GBR coral reefs...

We consider a simple plankton model with one phytoplankton autotroph population, one mixotrophic phytoplankton population that both photosynthesises and consumes the other phytoplankton, and one zooplankton predator population. The zooplankton predator may be either a specialist or a generalist grazer on the phytoplankton. We examine the influence...

We model the mutualism interactions between gobies and shrimp based on recent experimental work on the shrimp Alpheus floridans and the facultative and obligate gobies Ctenogobius saepepallens and Nes longus in the Bahamas. We show that the model is consistent with observations, and suggest that obligate mutualism may favour rapid speciation in gob...

Concentrations of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS), and DMS flux are reported for the Great Barrier Reef (GBR), Great Barrier Reef Lagoon (GBRL), and Coral Sea. Generally higher concentrations of dimethylsulfoniopropionate and DMS occurred in coral reef waters, compared with GBRL concentrations. DMS flux from GBR coral reefs...

It is proposed that emissions of volatile sulfur compounds by coral reefs contribute to the formation of a biologically-derived feedback on sea surface temperature (SST) through the formation of marine biogenic aerosol (MBA). The direction and strength of this feedback remains uncertain and constitutes a fundamental constraint on predicting the abi...

Pollination interactions are common, and their maintenance is critical for many food crops upon which human populations depend. Pollination is a mutualism interaction; together with predation and competition, mutualism makes up the triumvirate of fundamental interactions that control population dynamics. Here we examine pollination interactions (ne...

A simple model of obligate mutualist populations is presented in an extended consumer-resource (ECR) framework to resolve some of the deficiencies of traditional models. Varying parameters representing the costs of providing a mutualist benefit allows the model to smoothly and stably transition between many existing models of obligate mutualism. Va...

The discarding of plastic products has led to the ubiquitous occurrence of microplastic particles in the marine environment. The uptake and depuration kinetics of ingested microplastics for many marine species still remain unknown despite its importance for understanding bioaccumulation potential to higher trophic level consumers. In this study, An...

We investigate the correlation between stress-related compounds produced by corals of the Great Barrier Reef (GBR) and local atmospheric properties—an issue that goes to the core of the coral ecosystem’s ability to survive climate change. We relate the variability in a satellite decadal time series of fine-mode aerosol optical depth (AOD) to a cora...

Southern hemisphere humpback whales (Megaptera novaeangliae) rely on summer prey abundance of Antarctic krill (Euphausia superba) to fuel one of the longest-known mammalian migration on the planet. It is hypothesised that this species, already adapted to endure metabolic extremes, will be one of the first Antarctic consumers to show measurable phys...

The rapid development of earth observation technology has produced large quantities of remote-sensing data. Unsupervised classification (i.e. clustering) of remote-sensing images, an important means to acquire land-use/cover information, has become increasingly in demand due to its simplicity and ease of application. Traditional methods, such as k-...

In the first multi-year sampling effort for POPs in the eastern Antarctic atmosphere, 32 PCBs and 38 organochlorine pesticides were targeted in air collected with a high-flow-through passive sampler. Agricultural chemicals were found to dominate atmospheric profiles, in particular HCB and endosulfan-I, with average concentrations of 12,600 and 550...

Policy-and decision-makers require assessments of status and trends for marine species, habitats, and ecosystems to understand if human activities in the marine environment are sustainable, particularly in the face of global change. Central to many assessments are statistical and dynamical models of populations, communities, ecosystems, and their s...

We analyse a simple plankton system to provide a heuristic for more complex models such as Dynamic Green Ocean Models (DGOMs). Zooplankton foraging is either by generalist grazers that consume whatever they bump into or specialist grazers that actively seek particular prey. The zooplankton may further be classified as either facultative grazers tha...

We present a new method to find parameter sets that allow all populations to co-exist in multi-trophic level food web models in which the outcome of competition between populations at each trophic level is determined by R* theory. The method involves sequentially destabilising an eigenvalue at the boundary equilibrium point of the winning populatio...

Despite Antarctica's isolation from human population centres, persistent organic pollutants (POPs) are transported there via long range atmospheric transport and subsequently cold-trapped. The challenging nature of working in the Antarctic environment greatly limits our ability to monitor POP concentrations and understand the processes that govern...

The periodic trend to cetacean mass stranding events in the Australian island state of Tasmania remains unexplained. This article introduces the hypothesis that domoic acid poisoning may be a causative agent in these events. The hypothesis arises from the previously evidenced role of aeolian dust as a vector of iron input to the Southern Ocean; the...

Unsupervised image classification is an important means to obtain land-use/cover information in the field of remote sensing, since it does not require initial knowledge (training samples) for classification. Traditional methods such as k-means and Iterative self-organizing data analysis technique (ISODATA) have limitations in solving this NP-hard u...

Organochlorine pesticides (OCPs) were, for the first time, quantified in archived firn cores from East Antarctica representative of 1945–1957 and 1958–1967 (current era, C.E.). The core sections were melted under high-purity nitrogen atmosphere, and the meltwater was analysed. Methods allowed quantification of hexachlorocyclohexanes, heptachlor, tr...

The dynamics of plankton ecosystems have long been of interest to ecologists and mathematicians, with some of the earliest examples of chaotic dynamics being provided by ecological models. Mortality terms were initially identified as determinants of chaos in simple ecosystem models, but relatively little attention has been given to the role of graz...

This study contributes new data of the spatial variability of Persistent Organic Pollutants in the Indian-Pacific sector of the Southern Ocean and represents the first empirical data obtained from this region in 25 years. Paired high-volume atmospheric and seawater samples were collected along a transect between Australia and Antarctica to investig...

In this paper we extend the \(P_{1}P_{2}ZN\) model, introduced by Cropp and Norbury (J Plankton Res 31:939–963, 2009) to investigate the effects of specialist (or discriminate) and generalist (or indiscriminate) grazing (as parameterised by ρ) on a prey-prey-predator model for plankton, in the presence of a limiting nutrient. We also examine the in...

Multimedia models based on chemical fugacity, solved numerically, play an important role in investigating and quantifying the environmental fate of chemicals such as persistent organic pollutants (POPs). These models have been utilised extensively in the study of the local and global distribution of chemicals in the environment. This paper describe...

The analysis of trophically complex mathematical ecosystem models is typically carried out using numerical techniques because it is considered that the number and nonlinear nature of the equations involved makes the use of analytic techniques virtually impossible. In particular, building such models is a notoriously difficult task; most competing p...

The exchange of important greenhouse gases between the ocean and atmosphere is influenced by the dynamics of near-surface plankton ecosystems. Marine plankton ecosystems are modified by climate change creating a feedback mechanism that could have significant implications for predicting future climates, for example, the collapse or extinction of a p...

During the austral spring of 2009 several significant dust storms occurred in south-east Australia including the so-called ‘Red Dawn’ event in late September. Estimates of 2.5 Mt total suspended particulate sediment lost off the Australian coast in the 3000 km long dust plume make it the largest off-continent loss of soil ever reported. Much of thi...

Aeolian mineral dust input is thought to be a critical source of dissolved iron (dFe) for phytoplankton growth in some oceanic regions. Dust deposition has been considered a cause of coral reef demise in some sea regions. Several studies have shown a moderate correlation between the modelled flux of dust-derived iron and satellite-derived chlorophy...

The classical separate treatments of competition and predation and difficulties in providing a sensible theoretical basis for mutualism attest to the inability of traditional models to provide a synthesising framework for trophic interactions, a fundamental component of ecology. Recent approaches to food web modelling have focused on consumer-resou...

Mathematical biology/ecology teaching for undergraduates has generally relied on the Lotka-Volterra competition and predator-prey models to introduce students to population dynamics. Students are provided with an understanding of the application of dynamical system theory in simulating and understanding the behavior of the natural world, and they a...

This study investigated the role of a permanently manned Australian Antarctic research station (Casey Station) as a source of contemporary persistent organic pollutants (POPs) to the local environment. Polybrominated diphenyl ethers (PBDEs) and poly- and perfluoroalkylated substances (PFASs) were found in indoor dust and treated wastewater effluent...

The increase of algal biomass as a result of upwelling can be a major food source for marine life and such areas may become important fishing grounds. There are several studies of upwelling related to the East Australian Current (EAC) in the Eastern Australia coastal zone, but no comprehensive investigation of upwelling on the Southern Queensland c...

Humpback whales are iconic mammals at the top of the Antarctic food chain. Their large reserves of lipid rich tissues such as blubber predispose them to accumulation of lipophilic contaminants throughout their lifetime. Changes in the volumes and distribution of lipids in humpback whales, particularly during migration, could play an important role...

Cropp, R., and Norbury, J. 2014. Comment on “The paradox of the ‘paradox of the plankton’” by Record et al. – ICES Journal of Marine Science, 71: 293–295. The biodiversity of plankton ecosystems is no longer a paradox. The mathematical mechanisms that determine the coexistence of competitors in a general class of models, which includes almost all t...

Predicting how change will impact ecosystems requires the development of complex models. The complexity of ecosystem models often defies the power of analytical mathematical techniques so they are commonly solved using computers. A problem with this approach is the difficulty in assessing the credibility of model simulation results. We apply ecolog...

Iron-rich nanoparticles in aeolian mineral dust are of considerable importance to biogeochemical cycles. A major determinant of the chemical characteristics of nanoparticles is the parent sediment they are sourced from. The abrasion of dune sand has previously been shown to produce coarse dust (>1 μm) during the occurrence of aeolian saltation. In...

There is growing interest in models of marine ecosystems that deal with the effects of climate change through the higher trophic levels. Such end-to-end models combine physicochemical oceanographic descriptors and organisms ranging from microbes to higher-trophic-level (HTL) organisms, including humans, in a single modeling framework. The demand fo...

We develop a tool to assist in identifying a link between naturally occurring aeolian dust deposition and phytoplankton response in the ocean. Rather than examining a single, or small number of dust deposition events, we take a climatological approach to estimate the likelihood of observing a definitive link between dust deposition and a phytoplank...

Upwelling has been mentioned as a significant source of nutrients for Queensland continental shelf ecosystems. There are several studies of dynamic uplifts and upwelling caused by East Australian Current in the outer Great Barrier Reef and the New South Wales coast. However, there is no comprehensive study on upwelling in the waters to the south of...

Existing studies suggested that inshore parts of the Great Barrier Reef (GBR) lagoon are already or will soon become eutrophic as a result of anthropogenic nutrient enrichment. GBR phytoplankton dynamics generally displays a seasonal pattern, with algal standing stock (Chl) at an annual maximum during the summer wet season. Observations suggest tha...

The biodiversity of plankton ecosystems may no longer be a paradox, but the mechanisms that determine coexistence of explicit competitors in ecosystems remain a mystery. This is particularly so in ecosystem models, where competitive exclusion remains the dominant process. Climate and fish-eries models require plankton ecosystem sub-models that main...

We synthesize the generic properties of ecologically realistic multi-trophic level models and define criteria for ecological realism. We define an "ecospace" in which all ecologically realistic dynamics are confined, and construct "resource rays" that define the resources available to each species at every point in the ecospace. Resource rays for a...

The quantitative expression and monitoring of patch shape deformation is an important content of landscape ecology. In this paper, a new multi-vector method is put forward based on curve representation in differential geometry, which is the composition of Centroid Displacement Vector (CDV), Local Deformation Vector (LDV) and the unit normal vector...

Polar regions can be repositories for many persistent organic pollutants (POPs). However, comparatively little is known of the movement and behaviour of POPs in Antarctic ecosystems. These systems are characterised by strong seasonal effects of light on plankton dynamics. This work describes a mass-conserving, fugacity-based dynamic model to descri...

Analytic expressions for maximum chemical concentration attained in plants, and time this takes for uptake from surrounding soil were derived from a simple two-compartment soil/water–plant model. To illustrate, for the antibiotic norflxacin undergoing first order loss in the soil/water phase with a rate constant of 0.544 days−1, maximum concentrati...

Roads are important basic geographical phenomena and the automatic recogni- tion and extraction of road features from remote sensing images has many applica- tions. However, automated road extraction from high-resolution remote sensing imagery is problematic. In recent years, many approaches have been explored for automatic road extraction, particu...

Ocean dimethylsulfide (DMS) produced by marine biota is the largest natural source of atmospheric sulfur, playing a major role in the formation and evolution of aerosols, and consequently affecting climate. Several dynamic process-based DMS models have been developed over the last decade, and work is progressing integrating them into climate models...

Marine plankton ecosystems are an important component of biogeochemical cycling in the oceans. Operational plankton functional type (PFT) models, that group plankton according to their biogeochemical properties, are currently being developed to resolve biogenic gas exchange between the ocean and atmosphere, and to model the lowest trophic levels in...

During late 2002 and early 2003, southern Australia was in the grip of drought and experienced one of its most active dust storm seasons in the last 40 years with large dust plumes frequently advected over the adjacent Southern Ocean. We use meteorological records of dust activity, satellite ocean color, and aerosol optical depth data and dust tran...

The spectre of anthropogenic global climate change has focused attention on biogeochemical cycling in the oceans as marine plankton ecosystems are involved in the cycling of several compounds thought to have significant implications for climate. To better understand these processes, modellers are developing plankton functional type (PFT) models tha...

A plankton food web model is analysed using interaction parameter values appropriate to the upper mixed layer of the high latitude oceans. The dynamics of this four-variable system are analysed in terms of the dynamics of much simpler two-variable predator–prey subsystems. Thus, the food web's robust, periodic, four-dimensional dynamics are explain...

Yes Yes

The major source of reduced sulfur in the remote marine atmosphere is the biogenic compound dimethylsulfide (DMS), which is ubiquitous in the world's oceans and released through food web interactions. Relevant fluxes and concentrations of DMS, its phytoplankton-produced precursor, dimethylsulfoniopropionate (DMSP) and related parameters were measur...

A new one-dimensional model of DMSP/DMS dynamics (DMOS) is developed and applied to the Sargasso Sea in order to explain what drives the observed dimethylsulfide (DMS) summer paradox: a summer DMS concentration maximum concurrent with a minimum in the biomass of phytoplankton, the producers of the DMS precursor dimethylsulfoniopropionate (DMSP). Se...

Carbon sequestering in peatlands is believed to be a major climate-regulating mechanism throughout the late Phanerozoic. Since plant life first evolved on land, peatlands have been significant carbon sinks, which could explain significant parts of the large variations in atmospheric carbon dioxide observed in various records. The result is peat in...

The hypothesis that marine plankton ecosystems may effectively regulate climate by the production of dimethylsulphide (DMS) has attracted substantial research effort over recent years. This hypothesis suggests that DMS produced by marine ecosystems can affect cloud properties and hence the averaged irradiance experienced by the phytoplankton that p...

The potential for marine plankton ecosystems to influence climate by the production of dimethylsulphide (DMS) has been an important topic of recent research into climate change. Several General Circulation Models, used to predict climate change, have or are being modified to include interactions of ecosystems with climate. Climate change necessitat...

EXTENDED ABSTRACT The prospect of human-induced climate change has stimulated research into several biological processes that might affect climate. One such process that has attracted a substantial research effort is the so-called CLAW hypothesis (Charlson et al. 1987). This hypothesis suggests that marine plankton ecosystems may effectively regula...

Agent based modelling (ABM) environments are becoming increasingly popular for investigating the effects of land use change. The ABM environment enables models to be developed that simulate biophysical, economic and social processes at different spatial and temporal scales. The smallest spatial area modelled here is the paddock at a daily temporal...

The prospect of human-induced climate change provides a compelling imperative for an improved understanding of living systems, especially those involving ocean plankton that are proposed to have an important role in regulating climate. Ecosystems are complex, adaptive systems and mathematical modelling has proved to be a powerful tool in understand...

Excessive catalyst emissions from Fluidized Catalytic Cracking Units (FCCU) during start-up situations are common, and have been deemed ‘normal’, with little research conducted on determining their causes. A MATLAB model found to predict trends in emission rates under normal conditions has been expanded to better represent the actual processes insi...

Extensive experimental investigation of the wetting processes of fibre/liquid systems during air filtration (when drag and gravitational forces are acting) has shown many important features, including droplet extension, oscillatory motion, and detachment or flow of drops from fibres as airflow velocity increases. A detailed experimental study of th...

Landscape indices are popular for the quantification of landscape pattern. However, all landscape indices being used so far are scalar quantities, and measure patterns without considering sufficiently the pattern shape and the directionality together. Based on planar characteristics defined in mechanics such as centroid, moment of inertia, product...

Two hypotheses that postulate interactions between ocean biota and aerosols in the atmosphere have generated substantial research into marine systems. The stimulation of phytoplankton photosynthesis by the provision of iron, a micronutrient contained in deposited aeolian dust, (the "Iron Hypothesis"), and the contribution of dimethylsulphide (DMS)...

Extensive experimental investigation of the wetting processes of fibre-liquid systems during air filtration (when drag and gravitational forces are acting) has shown many important features, including droplet extension, oscillatory motion, and detachment of drops from fibres as airflow velocity increases, and also movement or flow of droplets along...

Dimethylsulphide (DMS) is produced by upper ocean ecosystems and emitted to the atmosphere where it may have an important role in climate regulation. Several attempts to quantify the role of DMS in climate change have been undertaken in modeling studies. We examine a model of biogenic DMS production and describe its endogenous dynamics and sensitiv...

No Yes

We have used a marine food‐web model, an atmosphere‐ocean general circulation model (GCM), and an empirical dimethylsulfide (DMS) algorithm to predict the DMS seawater concentration and the DMS sea‐to‐air flux in 10° latitude bands from 70°N to 70°S under contemporary and enhanced greenhouse conditions. The DMS empirical algorithm utilizes the food...

Dimethylsulphide (DMS) is produced by upper ocean ecosystems and emitted to the atmosphere, where it may have an important role in climate regulation. Several attempts to quantify the role of DMS in climate change have been undertaken in modeling studies. We examine a model of biogenic DMS production and describe its endogenous dynamics and sensiti...

Dimethyl sulfide (DMS) is a radiatively active trace gas produced by enzymatic cleavage of its precursor compound, dimethyl sulfoniopropionate (DMSP), which is released by marine phytoplankton in the upper ocean. Once ventilated to the atmosphere, DMS is oxidised to form non-sea-salt sulfate and methane sulfonate (MSA) aerosols, which are a major s...

Cropp and Gabric [Ecosystem adaptation: do ecosystems maximise resilience? Ecology. In press] used a simple phytoplanktonzooplankton-nutrient model and a genetic algorithm to determine the parameter values that would maximize the value of certain goal functions. These goal functions were to maximize biomass, maximize flux, maximize flux to biomass...