Toxin-producing Phytoplankton Research Articles

플랑크톤 패러독스

Hutchinson (1961) proposed that the large number of species in most plankton communities is remarkable in review of the competitive exclusion principle, which suggests that in homogeneous, well-mixed environments species that compete for the same resources cannot coexist. The principle of competitive exclusion would lead us to conclude that only a few species could coexist in such circumstances. Nevertheless, numerous competing species in most natural habitats are able to coexist, while generally only few resources (niches) limit these communities. It is coined “the paradox of plankton” by Hutchinson. We reviewed some literature of the proposed solutions and give a brief overview of the mechanisms proposed so far. The proposed mechanisms that we discuss mainly include spatial and temporal heterogeneity in physical and biological environment, externally imposed or self-generated spatial segregation, horizontal mesoscale turbulence of ocean characterized by coherent vortices, oscillation and chaos generated by several internal and external causes, stable coexistence and compensatory dynamic under fluctuating temperature in resource competition, and finally the role of toxin-producing phytoplankton in maintaining the coexistence and biodiversity of the overall plankton populations. Especially we sited Roy and Chattopadhyay ’s reviews and their toxin-producing hypothesis by phytoplankton. This review may be some information to study plankton communities and effect to put the solutions to the paradox that have been proposed over the years into perspective.

Stability analysis of coexistence of three species prey–predator model

In this paper, we have proposed a prey–predator model for the study of dynamical behaviors of three species such as toxin-producing Phytoplankton, Zooplankton and Fish in a fishery system. The stability condition, existence condition of equilibrium and bifurcation have also been established. In this paper, Holling type II functional response function has been considered to analysis of the proposed model. All equilibriums of the proposed system are determined, and the behavior of the system is also investigated near the positive equilibrium point. At the end, local stability of the system is analyzed by numerical illustrations.

Analysis of a toxin producing phytoplankton–zooplankton interaction with Holling IV type scheme and time delay

The present paper aims to study the interaction of toxin producing phytoplankton (TPP)–zooplankton (a prey–predator interaction) and its role in plankton ecology. The delay in the zooplankton predation is considered and its effect on the overall dynamic of phytoplankton–zooplankton interaction is studied. Moreover, Holling IV type response function is used for zooplankton grazing to account for the effect of toxication by the TPP population. It is shown that time delay can destabilise the given system and induce oscillation in population due to Hopf-bifurcation. Further stability of the bifurcating periodic solution is determined by using normal form theory and centre manifold arguments. Some numerical simulations are executed to validate the analytical findings.

A National Survey of Marine Biotoxins in Wild-Caught Abalone in Australia

The first national survey of Australian wild-caught abalone was conducted between September 2012 and December 2013. The aim of the survey was to determine the presence of paralytic shellfish toxins (PSTs), amnesic shellfish toxins (ASTs), and diarrhetic shellfish toxins (DSTs) in wild-caught abalone at levels above the current Codex marine biotoxin limits during the 2013 fishing season. Abalone (n = 190) were collected from 68 abalone-fishing blocks for which the combined annual harvest accounts for 80 % of Australian production. Concurrent seawater samples were collected and enumerated for potentially toxic phytoplankton. The foot and viscera tissues of each abalone sample were analyzed separately for PSTs, ASTs, and DSTs. No samples (abalone foot or viscera) contained toxins at levels exceeding the marine biotoxin limits stipulated by Codex. The resulting prevalence estimate suggests that less than 1.6 % of the commercially caught wild abalone population in Australia were contaminated with marine biotoxins at levels above the regulatory limit during the survey period. ASTs were detected at very low (trace) levels in the foot and viscera tissue of four and three abalone samples, respectively. To our knowledge, this represents the first reported detection of domoic acid in Australian abalone. PSTs also were detected at very low levels in 17 samples of abalone foot tissue and 6 samples of abalone viscera. The association between the low levels of ASTs and PSTs detected in abalone and the presence of potential toxin-producing phytoplankton in seawater samples was weak. DSTs were not detected in any abalone despite the detection of very low levels of DST-producing phytoplankton in a small number (9 of 77) of seawater samples. The results of this survey should be useful for public health risk assessments and provide additional evidence that the prevalence of marine biotoxins in Australian wild-caught abalone is very low.

Stoichiometric regulation of phytoplankton toxins

Ecological Stoichiometry theory predicts that the production, elemental structure and cellular content of biomolecules should depend on the relative availability of resources and the elemental composition of their producer organism. We review the extent to which carbon- and nitrogen-rich phytoplankton toxins are regulated by nutrient limitation and cellular stoichiometry. Consistent with theory, we show that nitrogen limitation causes a reduction in the cellular quota of nitrogen-rich toxins, while phosphorus limitation causes an increase in the most nitrogen-rich paralytic shellfish poisoning toxin. In addition, we show that the cellular content of nitrogen-rich toxins increases with increasing cellular N : P ratios. Also consistent with theory, limitation by either nitrogen or phosphorus promotes the C-rich toxin cell quota or toxicity of phytoplankton cells. These observed relationships may assist in predicting and managing toxin-producing phytoplankton blooms. Such a stoichiometric regulation of toxins is likely not restricted to phytoplankton, and may well apply to carbon- and nitrogen-rich secondary metabolites produced by bacteria, fungi and plants.

Dynamics of two phytoplankton populations under predation.

The aim of this paper is to investigate the manner in which predation and single-nutrient competition affect the dynamics of a non-toxic and a toxic phytoplankton species in a homogeneous environment (such as a chemostat). We allow for the possibility that both species serve as prey for an herbivorous zooplankton species. We assume that the toxic phytoplankton species produces toxins that affect only its own growth (autotoxicity). The autotoxicity assumption is ecologically explained by the fact that the toxin-producing phytoplankton is not mature enough to produce toxins that will affect the growth of its nontoxic competitor. We show that, in the absence of phytotoxic interactions and nutrient recycling, our model exhibits uniform persistence. The removal rates are distinct and we use general response functions. Finally, numerical simulations are carried out to show consistency with theoretical analysis. Our model has similarities with other food-chain models. As such, our results may be relevant to a wider spectrum of population models, not just those focused on plankton. Some open problems are discussed at the end of this paper.

Phytoplankton–zooplankton dynamics in the ‘presence’ or ‘absence’ of toxic phytoplankton

The inhibitory effects of toxin-producing phytoplankton (TPP) on zooplankton modulate the dynamics of marine plankton. In this article, we employ simple mathematical models to compare theoretically the dynamics of phytoplankton–zooplankton interaction in situations where the TPP are present with those where TPP are absent. We consider two sets of three-component interaction models: one that does not include the effect of TPP and the other that does. The negative effects of TPP on zooplankton is described by a non-linear interaction term. Extensive theoretical analyses of the models have been performed to understand the qualitative behaviour of the model systems around every possible equilibria. The results of local-stability analysis and numerical simulations demonstrate that the two model-systems differ qualitatively with regard to oscillations and stability. The model system that does not include TPP is asymptotically stable around the coexisting equilibria, whereas, the system that includes TPP oscillates for a range of parametric values associated with toxin-inhibition rate and competition coefficients. Our analysis suggests that the qualitative dynamics of the plankton–zooplankton interactions are very likely to alter due to the presence of TPP species, and therefore the effects of TPP should be considered carefully while modelling plankton dynamics.

Modeling the Role of Toxic Substances in a Phytoplankton-Toxic Phytoplankton-Zooplankton System

In this paper, a mathematical model has been proposed, which consists of three variables: non-toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton. In this model, an Monod- Haldane functional response is utilized to identify the grazing process of zooplankton due to the phytoplankton toxicity. The product of square of TPP density with square of NTP density is to depict the allelopathic influence on NTP. Numerical analysis indicates that the phytoplankton toxicity has a significant influence on the dynamical complexity and species biomass level through bifurcation diagrams. All these results are expected to be of significance in exploration of the dynamical complexity of ecosystems.

Spatiotemporal dynamics in a reaction–diffusion toxic-phytoplankton–zooplankton model

In this paper, we investigate the complex dynamics of a spatial toxic-phytoplankton–zooplankton model with Holling type-II functional response. Through a detailed analytical study of the reaction–diffusion model, we obtain some conditions for local and global stability and for diffusive instability with zero-flux boundary conditions of a positive equilibrium. On the basis of these results, we present the evolutionary processes of pattern formation that involve organism distribution and the interaction of a spatially distributed population with local diffusion. Then, novel numerical evidence of the time evolution of patterns controlled by diffusion and environmental carrying capability in the model are presented, and it is found that the model dynamics exhibits complex pattern replication. Additional studies reveal that pattern formation in the spatially extended model depends on the choice of the initial conditions. These results indicate that the interaction between toxin-producing phytoplankton and zooplankton in marine environments may be partly driven by the forces of diffusion or the environmental carrying capability.

Aggregation of toxin-producing phytoplankton acts as a defence mechanism – a model-based study

We propose a simple model of toxin-producing phytoplankton–zooplankton interactions in which the former is assumed to be able to detect the presence of zooplankton and to counteract it by forming patches and by releasing some toxic chemicals in the surrounding water. We observe that the formation of patch by the toxin-producing phytoplankton decreases the grazing pressure of zooplankton, resulting in stronger coupling between the interacting species determined by the fraction of the phytoplankton population that aggregates to form patches. Finally, the results were validated by comparing them with an alternative spatial model.

Modelling the Effects of Competing Toxin Producing Phytoplankton on a Zooplankton Population: Role of Holling Type-II Functional Response with Time-Lag

In this paper, a system consisting of two competing harmfu l phytoplankton and a zooplankton with Holling type-II functional response and discrete time lag is considered. A stable co-existence of all the species has been observed for the system without delay and the Hopf-b ifurcation phenomenon is observed for the interior equilibriu m po int. The Hopf-bifurcating solution is obtained for the critical values of parameters like predation rates and half saturation constants. Further, using the normal form theory, we have determined the direction and the stability of the Hopf-bifurcation solution. The introduction of time delay in the system also shows the Hopf-bifurcat ion as the delay parameter passes through a critical value. Finally, the numerical simu lation is carried out to support the theoretical results.

Toxic phytoplankton-induced spatiotemporal patterns

Here we consider a reaction diffusion system of three plankton populations, a zooplankton feeding on two phytoplankton populations, in two different settings. Firstly, the two phytoplanktons are both non-toxic and both enhance the growth of the grazing zooplankton. Secondly, we assume that one of the phytoplankton releases toxin and thereby inhibits the growth of the zooplankton. Our analytic and numerical study shows that the spatiotemporal distribution of the plankton species is uniform when both phytoplankton populations are non-toxic. However, in the presence of toxin-producing phytoplankton, the biomass distribution of all the plankton populations becomes inhomogeneous.

Monitoring phytoplankton and marine biotoxins in production waters of the Netherlands: results after one decade

Shellfish products may be contaminated with marine biotoxins which, after consumption, may lead to human illness. The Netherlands has a regular monitoring programme for marine biotoxins and the possible toxic phytoplankton in shellfish production waters. The aim of the current study was to evaluate the presence of potential toxic phytoplankton species and marine biotoxins in Dutch production waters over the last decade, and to analyse the relationship between toxin levels and abundance of possible causative phytoplankton species. The results of the monitoring programme of the period 1999–2009 were used. The presence of Alexandrium spp. were negligible, but Pseudo-nitzschia spp. and phytoplankton causing diarrhetic shellfish poisoning (DSP toxin-producing phytoplankton) were present in nearly all three main production areas and years. The main DSP toxin-producing species was Dinophysis acuminata followed by D. rotundata and Prorocentrum lima. Toxins causing paralytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) were present in only a few individual shellfish samples, all at low levels. At the end of 2002, an episode of DSP toxicity was recorded, based on the rat bioassay results. Of the samples that were chemically analysed for DSP toxins in 2007 and 2008, about half of the samples in 2007 contained these toxins, although levels were low and no positive results were obtained using the rat bioassay. There was a slight positive correlation between concentrations of DSP toxin-producing phytoplankton and levels of DSP toxins in 2007. Increased DSP toxin levels were found up to 5 weeks after the peak in DSP toxin-producing phytoplankton. This positive, but weak, relationship needs to be confirmed in future research using more samples and chemical methods to quantify the presence of DSP toxins. If this relationship is further substantiated and quantified, it could be used within the current monitoring programme in the Netherlands to predict the risk areas regarding DSP toxicity in shellfish.

A delay model for viral infection in toxin producing phytoplankton and zooplankton system

An eco-epidemiological delay model is proposed and analysed for virally infected, toxin producing phytoplankton (TPP) and zooplankton system. It is shown that time delay can destabilize the otherwise stable non-zero equilibrium state. The coexistence of all species is possible through periodic solutions due to Hopf bifurcation. In the absence of infection the delay model may have a complex dynamical behavior which can be controlled by infection. Numerical simulation suggests that the proposed model displays a wide range of dynamical behaviors. Different parameters are identified that are responsible for chaos.

A simple mathematical model for seasonal planktonic blooms

AbstractWe show how the inclusion of the defense strategy by different species can alter the prediction of simple models. One of the defense strategy by the phytoplankton population against their grazer is the release of toxic chemicals. In turn the zooplankton population reduces there predation rate over toxin producing phytoplankton (TPP) to protect themselves from those toxic chemicals. Thus, when the level of toxicity is high, the grazing pressure is low and when the level of toxicity is low or when the toxin is absent, the grazing pressure is high. Here we have considered a TPP–zooplankton system where the rate of toxin liberation and the predation rate vary with zooplankton abundance. We observe that our proposed model has the potential to show different dynamical behaviour that are similar to that seen in real‐world situations. Further, we consider three different functional forms for the distribution of the toxins and compare them using latin hypercube sampling technique and found that the functional forms seem to have no effect in determining the final outcome of the system. Copyright © 2009 John Wiley & Sons, Ltd.

Role of competition in phytoplankton population for the occurrence and control of plankton bloom in the presence of environmental fluctuations

Termination of harmful algal blooms (HABs) and coexistence of phytoplankton–zooplankton populations are of great importance to human health, ecosystem, environment, tourism and fisheries. In this paper, we propose a three component model consisting of non-toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton (Z). The growth of zooplankton species is assume to reduce due to toxic chemicals released by TPP population. We have extended the model proposed by Chattopadhyay et al. [Chattopadhyay, J., Sarkar, R.R., Pal, S., 2004. Mathematical modelling of harmful algal blooms supported by experimental findings. Ecol. Comp. 1, 225–235] by including competition terms between TPP and NTP. We observe the effect of competition factors both in the presence and absence of the environmental fluctuation. From our field as well as model analysis we observe that competition helps in the coexistence of the species, but if the effect of competition is very high on the TPP population, it results in planktonic bloom. It is shown that the coexistence equilibrium loses its stability when the competition coefficient crosses a critical value and resulting Hopf-bifurcation around the positive equilibrium depicting oscillations phenomena of the populations.

Comparative accumulation and composition of lipophilic marine biotoxins in passive samplers and in mussels (M. edulis) on the West Coast of Ireland

Monitoring of lipophilic marine toxins was carried out in three shellfish production sites on the West Coast of Ireland. The toxins were monitored using passive samplers (solid phase adsorption toxin tracking; SPATT) and toxin-free mussels that were replaced weekly in the selected sampling stations. The toxin profiles and concentrations obtained in the SPATT and in the transplanted mussels were compared with those observed in indigenous (native) mussels from each production site as well as with the phytoplankton that was detected in the water. Numerous lipophilic toxins were detected in the SPATT discs by ultra-performance liquid-chromatography–mass spectrometry/mass spectrometry (UPLC–MS/MS) and included okadaic acid (OA), dinophysistoxin-2 (DTX2), pectenotoxin-2 (PTX2), AZA1, AZA2, yessotoxin (YTX) and SPX-13-DesMe-C. The accumulation rate of toxins in the indigenous mussels and in the SPATT discs correlated well. Toxins were detected in all SPATT discs from all locations, even in the absence of toxin-producing phytoplankton, as observed previously by other research groups. It is quite clear from our data that the presence of okadaic acid in the water (even at high concentrations) did not induce toxicity in the transplanted mussels in the absence of phytoplankton. A severe toxic event of azaspiracids (AZAs) occurred in one of the sampling stations. The SPATT discs accumulated predominantly AZA1 and -2 suggesting that both toxins are biosynthesized by the AZA-producing organism. As opposed to the DSP event, the AZA event resulted in the contamination of the transplanted mussels for several consecutive weeks. This is the first study that reports the presence of YTX and SPX-13-DesMe-C in Irish waters. In our study conditions, the SPATT did not enable the forecasting of shellfish contamination as the increase in toxin concentration occurred at the same time in the shellfish and in the SPATT.

Spatial Interaction Among Nontoxic Phytoplankton, Toxic Phytoplankton, and Zooplankton: Emergence in Space and Time

In homogeneous environments, by overturning the possibility of competitive exclusion among phytoplankton species, and by regulating the dynamics of overall plankton population, toxin-producing phytoplankton (TPP) potentially help in maintaining plankton diversity-a result shown recently. Here, I explore the competitive effects of TPP on phytoplankton and zooplankton species undergoing spatial movements in the subsurface water. The spatial interactions among the species are represented in the form of reaction-diffusion equations. Suitable parametric conditions under which Turing patterns may or may not evolve are investigated. Spatiotemporal distributions of species biomass are simulated using the diffusivity assumptions realistic for natural planktonic systems. The study demonstrates that spatial movements of planktonic systems in the presence of TPP generate and maintain inhomogeneous biomass distribution of competing phytoplankton, as well as grazer zooplankton, thereby ensuring the persistence of multiple species in space and time. The overall results may potentially explain the sustainability of biodiversity and the spatiotemporal emergence of phytoplankton and zooplankton species under the influence of TPP combined with their physical movement in the subsurface water.

Nutrient-limited toxin production and the dynamics of two phytoplankton in culture media: A mathematical model

In this paper we have proposed and analyzed a simple mathematical model consisting of four variables, viz., nutrient concentration, toxin producing phytoplankton (TPP), non-toxic phytoplankton (NTP), and toxin concentration. Limitation in the concentration of the extracellular nutrient has been incorporated as an environmental stress condition for the plankton population, and the liberation of toxic chemicals has been described by a monotonic function of extracellular nutrient. The model is analyzed and simulated to reproduce the experimental findings of Graneli and Johansson [Graneli, E., Johansson, N., 2003. Increase in the production of allelopathic Prymnesium parvum cells grown under N- or P-deficient conditions. Harmful Algae 2, 135–145]. The robustness of the numerical experiments are tested by a formal parameter sensitivity analysis. As the first theoretical model consistent with the experiment of Graneli and Johansson (2003), our results demonstrate that, when nutrient-deficient conditions are favorable for the TPP population to release toxic chemicals, the TPP species control the bloom of other phytoplankton species which are non-toxic. Consistent with the observations made by Graneli and Johansson (2003), our model overcomes the limitation of not incorporating the effect of nutrient-limited toxic production in several other models developed on plankton dynamics.

Mathematical modelling on harmful algal blooms in the presence of toxic substances

AbstractEffect of toxin producing plankton and its control is an intriguing problem in marine plankton ecology. In this paper we have proposed a three‐component model consisting of a non‐toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton (Z), where the growth of zooplankton species reduce due to toxic chemicals released by phytoplankton species. It is observed that the three components persist if the predation rate of zooplankton population on toxic phytoplankton is bounded in certain regions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)