Distribution Of Plankton Research Articles

Plankton distribution and diversity: a case study of earthen fish ponds in the Obubra Campus of Cross River University of Technology

Our knowledge of the consumption of plankton by fish is still fragmentary. Trophic links between fish and plankton are often loose because plankton is a changing assemblage of pelagic organisms of valuable nutritional value. The objectives of the study were to determine the distribution and diversity of planktons in the fish ponds. Water samples for plankton analysis were collected monthly (January – December), along with water samples used for the determination of physico-chemical parameters in 250ml bottles in Ponds 1,2 and 5. The freshwater sample was mixed gently and pipetted into 5ml plankton chamber containing 2 drops of Lugol’s solution. The Lugol’s solution which served as fixative also enhanced sedimentation of the organisms and was left overnight before analyzing plankton using Zeiss inverted plankton microscope and plankton determination keys. Data was analyzed using Shannon-Weaner diversity index, species richness, means and analysis of varians (ANOVA).The results showed that the highest species richness for dry season phytoplankton value of 27 was recorded in Pond 2, with the highest Shannon-Weaner diversity index value of 0.5401 in pond 5. Merismopaedia elegans with 3,434 in pond 2 was the most abundant phytoplankton species and chlorophyceae the most dominant taxa. The rainy season zooplankton species richness values (5 in pond 2) were higher than that of the dry season (3 in pond 3) with the highest Shannon-Weaner index value of 0.3501 recorded in pond 1. The most abundant zooplankton species Asplanchna species 57 was recorded in pond 2. Significant differences (p

Behavior constrains the dispersal of long-lived spiny lobster larvae

Behavior such as ontogenetic vertical migration (OVM) limits the transport of marine larvae with short pelagic larval durations (PLDs), but its effect on the supposed long-distance disper- sal of larvae with long PLDs is unknown. We conducted laboratory tests of ontogenetic change in lar- val phototaxis and examined size-specific patterns of larval distribution in the plankton to character- ize OVM in the Caribbean spiny lobster Panulirus argus during its long (6 mo) PLD. We then used a coupled biophysical model to explore the consequences of OVM and hydrodynamics on larval P. argus dispersal in the Caribbean Sea. Larvae reared in the laboratory were positively phototatic for the first 2 mo and then avoided light thereafter, similar that seen in the planktonic distribution of same-sized larvae. Simulations of larval dispersal from 13 spawning sites in the Caribbean Sea pre- dicted that twice as many larvae would recruit to nurseries if they displayed OVM compared with passive dispersers. Larvae with OVM typically settled 1000 km away. OVM also produced an asymmetrical bimodal pattern of dispersal dominated by larvae that settled near their origin (~60%), but showed a second peak of larvae that dispersed over long distances (~20%). Hydrodynamics created subregional differ- ences in the potential for self-recruitment. Our findings suggest that (1) larval behavior constrains the dispersal of even long-lived larvae, particularly in tandem with retentive oceanographic environ- ments, and (2) larval sources of P. argus in the Caribbean Sea cannot be estimated from passive trans- port and surface circulation.

Structure-dependent, protistan grazing and its implication for the formation, maintenance and decline of plankton patches

Plankton distributions are frequently patchy and phytoplankton patches have long been suggested as important resources in otherwise nutritionally dilute environments. The present study confirms this hypothesis empirically in a coastal fjord with naturally forming phytoplankton patches and examines the implications for plankton distributions, abundance and rates of patch formation, maintenance and decline. Phytoplankton patches were identified using a CTD mounted fluorometer and sampled with a horizontally mounted 2 l Niskin bottle in 3 separate field seasons in summer 2007 and 2008 and spring 2009. We quantified chl a and macronutrient concentrations as well as phyto- plankton growth and zooplankton (<200 µm) grazing rates. Average phytoplankton growth was equal inside and outside of patches (0.34 ± 0.07 d -1 ) and there was no indication of nutrient limitation to phytoplankton growth. Average grazing rate inside patches (0.25 ± 0.03 d -1 ) was significantly higher than outside of patches (0.09 ± 0.03 d -1 ). Grazing pressure was not simply a function of prey availability; there was no significant relationship between grazing rate and initial chl a concentration. Protistan grazing consumed on average 65% of primary production within and 26% outside of patches. Model predictions of population dynamics suggest that protistan grazing focused within patches and more rapid phytoplankton accumulation outside of patches eroded layer structures within hours to days. Formation of plankton patches due to phytoplankton growth was not supported by the data. Averaging rates, irrespective of phytoplankton distribution, greatly overestimated layer persistence and minimally underestimated primary production and its availability to higher trophic levels. These results emphasize empirically the importance of predator-prey interactions to the ubiq- uitous phenomenon of plankton patchiness and ultimately microbial food web dynamics.

Phytoplankton distribution across the southeast Adriatic continental and shelf slope to the west of Albania (spring aspect)

We present the first insight to the oceanography of the southeastern Adriatic Sea, where coastal water influenced by Albanian rivers comes into contact with the inflowing oligotrophic Eastern Adriatic Current (Ionian Surface Water and Levantine Intermediate Water). A distinct plankton distribution was observed on each side of the shelf break hydrographic boundary in May 2009, during gradual warming of the surface waters. The prochlorophytes accumulated along the nutricline above the shelf and continental slope. The phosphorus limited inshore waters were dominated by a small diatom Chaetoceros circinalis, dinoflagellates, cryptophytes, autotrophic picoplankton, and heterotrophic nanoplankton. The offshore surface layer was characterized by bigger nanoplankton (coccolithophorids, green flagellates). Low nutrient concentrations influence relatively low productivity not only above the Albanian shelf but also further to the north along the Montenegrine and Croatian coastal Adriatic Sea.

Dynamics of phytoplankton and picoplankton over a tidal cycle in a subtropical lagoon

The influences of a tidal cycle on the distribution of autotrophic plankton were investigated in a hyper-eutrophic lagoon designated as a scenic area. Results showed that the highest concentrations of picoplankton and phytoplankton were found in the middle and inner part of the lagoon, irrespective of the tides. The MDS result also revealed that phytoplankton communities, dominated by Ceratium furca, were similar among stations in the inner bay during both flood tides and ebb tides. The time series sampling results at the inlet-outlet channel revealed that almost the same amounts of phytoplankton and picoplankton were carried through the channel during flood and ebb tides, with no trend in nutrient fluctuations except for phosphate which had a net loss from the lagoon. The results showed that tidal cycles do not effectively flush away phytoplankton and picoplankton from the lagoon, and the blooming of phyto- and picoplankton is inevitable should the situation stay the same. Steps are needed to alleviate the eutrophication condition instead of depending on the natural process such as tidal cycle.

Planktonic Biodiversity of Bhoj Wetland, Bhopal, India

Biodiversity found on Earth today consists of many millions of distinct biological species, which is the product of nearly 3.5 billion years of evolution. This article deals with planktonic distribution of Bhoj Wetland,Bhopal, India . Bhoj Wetland comprises of two lakes i.e. Upper and Lower lakes of Bhopal. The Upper lake is shallow, highly stratified and oligotrophic lake while Lower lake is eutrophic lake. Samples were collected fromUpper lake at two sampling stations and in Lower lakes from three sampling stations with their reference stations. The work was carried out for a period of two year (i.e. 2005-2006) in these contrasting lakes.

Physical constraints in the deep hypolimnion of a subalpine lake driving planktonic Bacteria and Archaea distribution

The study of the hydrodynamics of the hypolimnion of a deep holo-oligomictic lake (Lake Maggiore, Northern Italy, zmax¼370 m) during the last 28 years showed that hypolimnetic waters remained isolated, not exchanging with the mixing zone even in winter when the full overturn conditions are most likely. The thickness of the isolated layer can range from 100 to 300 m. Thus, water masses of variable size reside in the lake for many years, and their physical and chemical conditions remain relatively unaffected by seasonal variability and epilimnetic imputs. In the hypolimnetic waters prokaryote abundance is three times lower than in the mixing layer but cell size is significantly higher. In addition, the relative abundance of Archaea and Crenarchaeota increases with depth in respect to that of Bacteria. The heterogeneous distribution of the two domains within the habitat can be attributed to the existence in the same environment of isolated water masses.

THE ROLE OF BIOCONVECTION IN PLANKTON POPULATION WITH THERMAL STRATIFICATION

This paper investigates hydrodynamic processes of suspended planktonic population within a thermal stratification to represent a thermocline, in using a model of coupled equations: Navier–Stokes' equation for the fluid dynamic motion, Fisher's equation for the planktonic population with logistic growth, energy conservation equation for thermal effects and the Boussinesq approximation for the dependence on mass density of plankton. The planktonic population is assumed to be slightly denser than the fluid and to follow logistic growth. A numerical investigation is conducted to study patterns of plankton distribution under thermal stratification, and we adopt the finite volume method for solving the system of governing equations in simulations. It is found that thermal stratification constrains the feedback between hydrodynamic and plankton dynamics. More precisely, when temperature is lower in the upper than in the lower layer, the temperature gradient is destabilizing and both convection mechanisms — plankton motility (i.e. taxis behavior that can induce bioconvection) and temperature gradient — are additive. In the case of higher temperature in the upper than the lower layer, which applies to most natural systems, thermal stratification can dampen bioconvection and induce oscillatory dynamics if plankton diffuses faster than temperature. In all cases, if hydrodynamic and demographic time scales overlap, plankton growth rate has a strong effect on hydrodynamic processes involving both thermal convection and convection created by gravitaxis mechanism. Our study thus reveals the potential feedback between hydrodynamic and local demographic processes in plankton populations.

Persistence of cluster synchronization under the influence of advection

We present a study on the emergence of spatial structure in plankton dynamics under the influence of stirring and mixing. A distribution of plankton is represented as a lattice of nonidentical, interacting, oscillatory plankton populations. Each population evolves according to (i) the internal biological dynamics represented by an NPZ model with population-specific phytoplankton growth rate, (ii) sub-grid-cell stirring and mixing parameterized by a nearest-neighbor coupling, and (iii) explicit advection resulting from a constant horizontal shear. Using the methods of synchronization theory, the emergent spatial structure of the simulation is investigated as a function of the coupling strength and rate of advection. Previous work using similar methods has neglected the effects of explicit stirring (i.e., at scales larger than the grid cell), leaving as an open question the relevance of the work to real marine systems. Here, we show that persistent spatial structure emerges for a range of coupling strengths for all realistic levels of surface ocean shear. Spatially, this corresponds to the formation of temporally evolving clusters of local synchronization. Increasing shear alters the spatial characteristics of this clustering by stretching and narrowing patches of synchronized dynamics. These patches are not stretched into stripes of synchronized abundance aligned with the flow, as may be expected, but instead lie at an angle to the flow. This study shows that advection does not diminish the relevance of conclusions from previous studies of spatial structure in plankton simulations. In fact, the inclusion of advection adds characteristic filamental structure, as observed in real-world plankton distributions. The results also show that the ability of coupled oscillators to synchronize depends strongly on the spatial arrangement of oscillator natural frequencies; under the influence of advection, therefore, the impact of the coupling strength on the emergent spatial structure of a biophysical simulation is time-dependent.

Modelling the effects of variable salinity on the temporal distribution of plankton in shallow coastal lagoons

In shallow lagoons, there is a much greater ecological diversity than fully marine water bodies and communities comprise of representatives from both freshwaters and coastal sea. In the present study, an attempt has been made, through mathematical modelling, to study the effect of changing salinity on freshwater and marine plankton. The model proposed here is a five-compartment (Nutrient ( N), Freshwater phytoplankton ( P), Marine phytoplankton ( Q), Zooplankton ( Z) and Detritus ( D)) ecological model. The unique feature of the model is its ability to simulate plankton dynamics, as a response to salinity variations, with freshwater and marine species of phytoplankton represented separately. Numerical experiments and sensitivity analysis show that changes in salinity levels, nutrients and grazing are the controlling factors. For the case of intermediate salinity (17 psu approx.), the nutrient availability and palatability by zooplankton play a significant role. It is in this case, the two species are found to coexist. As a case study, the model is applied to Chilika Lagoon (19°28′N–19°54′N and 85°06′E–85°36′E), the largest brackish water lagoon on the east coast of India which has distinct and variable characteristics. The model is able to reproduce most of the significant characteristics of the phytoplankton distribution in Chilika, viz., bimodal oscillations, major plankton peaks and increased productivity after the salinity level was increased due to the opening of a new mouth connecting Bay of Bengal.

Microphytobenthos and phytoplankton in the Severn estuary, UK: Present situation and possible consequences of a tidal energy barrage

Information on the distribution of microphytobenthos (micro-algae forming biofilms on sediment surfaces) and phytoplankton in the Severn estuary is reviewed. Microphytobenthos (MPB) are widely distributed in salt marsh and mudflat environments, with biomass levels lower than in other estuaries (average 53mg chl am−2 on mud, 12mg chl am−2 on sand). Seasonal and spatial patterns occur in the species composition of biofilms. Large areas of the Severn have not been surveyed, but it is likely that MPB are abundant in these regions. Dissolved inorganic N, P and Si concentrations are high in the upper estuary (>400μM nitrate,>10μM phosphate,>140μM silicate) and decrease seaward. Phytoplanktonic chl a concentrations are low in the main estuary (2.2μg chl aL−1), but increase in the Bristol Channel and at the head of the estuary (>10μg chl aL−1). High turbidity is the likely cause for low phytoplankton activity. Annual production of MPB was estimated at 33gCm−2 of inter-tidal areay−1 in the Severn estuary. This estimated benthic primary production would utilise 3.9% and 4.9% of the annual estuarine N and P loads. Construction of tidal energy barrages is estimated to significantly reduce annual estuarine MPB production (by 77% for the Cardiff–Weston barrage). It is unlikely that any potential increases in MPB biomass on remaining inter-tidal areas will be sufficient to compensate for these losses. In general, the data coverage for benthic and planktonic distribution, production and related nutrient cycles is extremely limited and significant new research work is needed to enable more definite predictions of the post-barrage situation to be made.

Imaging of plankton specimens with the lightframe on-sight keyspecies investigation (LOKI) system

Zooplankton is a key element in aquatic food webs. Rapid mapping of abundance, combined with information on taxonomic and size composition is necessary to understand ecosystem dynamics. Classical sampling with towed plankton nets does not allow resolving fine scale distributions along hydrographic gradients (e.g. fronts and clines) although such structures determine community assemblages and trophic interactions. Furthermore, sample analysis is labor intensive and time consuming. To overcome these shortcomings, Lightframe On-sight Keyspecies Investigation (LOKI), a new imaging device, was developed for sensing spatial variability of plankton distribution on scales below the 1 m level. Here, we give a brief description of the LOKI system and demonstrate its potential for taxonomic identification using images of various zooplankton taxa collected in the south east Pacific.

Line transects, environmental data and GIS: Cetacean distribution, habitat and prey selection along the Barents Sea shelf edge

Cetacean observations obtained during sighting surveys for abundance estimation can also be used to investigate cetacean habitat and prey selection, the principal processes underlying cetacean distributions. In this paper, we investigate habitat and prey selection of minke (Balaenoptera acutorostrata), fin (B. physalus) and sperm (Physeter macrocephalus) whales and Lagenorhynchus (Atlantic white-sided L. acutus and white-beaked L. albirostris) dolphins observed along predetermined cruise tracks along the Barents Sea shelf edge in 2000, 2001 and 2002. The observations were combined with simultaneously collected data on habitat (depth, sea surface temperature, and temperature gradients) and prey (plankton, 0-group fish, capelin and herring) distributions in a GeographicInformation System (GIS) to investigate habitat and prey selection. Minke whales were associated with cold waters and herring, and capelin in years with low herring abundance. Fin whales were mainly associated with northern cold and deep waters, as well as capelin, 0-group fish and plankton. Lagenorhynchus dolphins were associated with capelin. Finally, sperm whales were associated with deep waters and 0-group fish. Sperm whales were probably indirectly attracted to 0-group fish through preying on predatory fish such as Sebastes spp. and the squid Gonatus spp. The cetacean species responded differently to annual variation in habitat and prey distributions. Minke and fin whale distributions and abundances remained similar between years within the study area, suggestingthat these species are generalists responding to environmental changes by switching between prey species. Conversely, Lagenorhynchus dolphins shifted northwards, likely due to tracking the shifting capelin distributions. The results are discussed in light of how such cetacean habitat and cetacean prey relationships can be valuable for the proper assessment of population sizes and trends, both through guiding the design of sighting surveys and assessing whether changes in abundances within fixed surveyed areas are due to distribution shifts or changes in population sizes.

Mesoscale variability modulates seasonal changes in the trophic structure of nano- and picoplankton communities across the NW Africa-Canary Islands transition zone

The variability of picoplankton and nanoplankton autotrophic ( A) and heterotrophic ( H) communities was studied along a zonal gradient extending from the NW African shelf to 500 km offshore in two contrasting seasons of the year: early spring (spring) and summer (summer). Plankton abundance was significantly higher in summer than in spring. In particular, heterotrophic prokaryotes (HP) and Prochlorococcus (Proc) were an order of magnitude more abundant in summer, presumably due to a higher loading of dissolved organic matter and higher temperatures. The average ratio of A to H biomass was lower during the summer. Over the African shelf, picoplankton was lowest during summer, while both the autotrophic and heterotrophic nanoflagellates (ANF and HNF) showed the highest abundances. In contrast, in spring, the highest abundance of Picoeukaryotes (PE) and Synechococcus (Syn) was found over or close to the shelf. The offshore sampling sections intersected a complex area of strong mesoscale variability, which affected the plankton distribution. In summer, the entrainment of an upwelling filament around a cyclonic eddy provoked the increase of HP and Syn abundances by about one order of magnitude over the surrounding waters, while PE were more abundant over the core of the eddy (probably due to nutrient pumping). In spring, HP and Syn were more abundant at the boundaries of an anticyclonic eddy and in the filament (where PE also increased). Proc abundance increased up to one order of magnitude in the core of the eddy and in the eddy-oceanic waters front. ANF and HNF showed the highest abundances in the filament and the eddy. In summary, although seasonality affects the background variability in microplankton communities, the mesoscale variability found in the Canary Islands transition zone strongly modulates the patterns of distribution, abundances and changes in community structure, altering the A to H ratio and concomitantly playing a key role modifying the carbon pathways within the food web in the region.

Influence of turbulent advection on a phytoplankton ecosystem with nonuniform carrying capacity

In this work we study a plankton ecosystem model in a turbulent flow. The plankton model we consider contains logistic growth with a spatially varying background carrying capacity and the flow dynamics are generated using the two-dimensional (2D) Navier-Stokes equations. We characterize the system in terms of a dimensionless parameter, gamma identical with TB/TF, which is the ratio of the ecosystem biological time scales TB and the flow time scales TF. We integrate this system numerically for different values of gamma until the mean plankton reaches a statistically stationary state and examine how the steady-state mean and variance of plankton depends on gamma. Overall we find that advection in the presence of a nonuniform background carrying capacity can lead to very different plankton distributions depending on the time scale ratio gamma. For small gamma the plankton distribution is very similar to the background carrying capacity field and has a mean concentration close to the mean carrying capacity. As gamma increases the plankton concentration is more influenced by the advection processes. In the largest gamma cases there is a homogenization of the plankton concentration and the mean plankton concentration approaches the harmonic mean, <1/K>(-1). We derive asymptotic approximations for the cases of small and large gamma. We also look at the dependence of the power spectra exponent, beta, on gamma where the power spectrum of plankton is proportional to k(-beta). We find that the power spectra exponent closely obeys beta=1+2/gamma as predicted by earlier studies using simple models of chaotic advection.

Hurricane‐driven alteration in plankton community size structure in the Gulf of Mexico: A modeling study

This was the first study to analyze phytoplankton and zooplankton community size structure during hurricane passage. A three‐dimensional biophysical model was used to assess ecosystem dynamics, plankton biomass, and plankton distribution in the Gulf of Mexico during Hurricane Katrina (2005). Model simulations revealed that large phytoplankton were most responsive to hurricane‐induced turbulent mixing and nutrient injection, with increases in biomass along the hurricane track. Small phytoplankton, microzooplankton, and mesozooplankton biomass primarily shifted in location and increased in spatial extent as a result of Hurricane Katrina. Hurricane passage disrupted the distribution of plankton biomass associated with mesoscale eddies. Biomass minimums and maximums that resided in the center of warm‐ and cold‐core eddies and along eddy peripheries prior to hurricane passage were displaced during Hurricane Katrina.

Impacts of climate change on fisheries

Evidence of the impacts of anthropogenic climate change on marine ecosystems is accumulating, but must be evaluated in the context of the “normal” climate cycles and variability which have caused fluctuations in fisheries throughout human history. The impacts on fisheries are due to a variety of direct and indirect effects of a number of physical and chemical factors, which include temperature, winds, vertical mixing, salinity, oxygen, pH and others. The direct effects act on the physiology, development rates, reproduction, behaviour and survival of individuals and can in some cases be studied experimentally and in controlled conditions. Indirect effects act via ecosystem processes and changes in the production of food or abundance of competitors, predators and pathogens. Recent studies of the effects of climate on primary production are reviewed and the consequences for fisheries production are evaluated through regional examples. Regional examples are also used to show changes in distribution and phenology of plankton and fish, which are attributed to climate. The role of discontinuous and extreme events (regime shifts, exceptional warm periods) is discussed. Changes in fish population processes can be investigated in experiments and by analysis of field data, particularly by assembling comparative data from regional examples. Although our existing knowledge is in many respects incomplete it nevertheless provides an adequate basis for improved management of fisheries and of marine ecosystems and for adapting to climate change. In order to adapt to changing climate, future monitoring and research must be closely linked to responsive, flexible and reflexive management systems.

Cluster synchronisation: A mechanism for plankton patchiness and a simulation pitfall

We present a study on the emergence of spatial variability, or patchiness, in biophysical simulations of plankton ecosystems. Using a standard approach to modelling such ecosystems, we represent a distribution of plankton as a lattice of non-identical interacting oscillatory populations. Spatial variation is imposed in population parameters, such as maximum growth rate, leading to a spread in the natural (uncoupled) population properties. Using the methods of synchronisation theory, the emergent spatial structure of the coupled system is investigated as a function of the strength of interaction between populations. Surprisingly, a range of coupling strength is found to induce a tenfold increase in the spread in frequency of oscillation of populations in comparison with the uncoupled level of spatial variation. This apparent desynchronisation corresponds to the formation of temporally evolving clusters of local synchronisation: the interplay of grid-cell scale variability and dispersal between populations leads to patchiness at larger scales. However, the occurrence and length-scale of this patchiness is found to be sensitive to typical simulation parameters such as spatial resolution and strength of dispersal, with emergent spatial structure altering abruptly from patchy to homogeneous as these parameters are varied. These results indicate that whilst cluster synchronisation may be a genuine mechanism for the formation of spatial structure in plankton distributions, biophysical modellers should be aware of the possibility of artificial patchiness arising from the basic physical structure of their model.

Phytoplankton pigments and functional types in the Atlantic Ocean: A decadal assessment, 1995–2005

The phytoplankton pigment composition (chlorophylls and carotenoids) from 17 Atlantic Meridional Transect (AMT) cruises over the period 1995–2005 was analysed to determine the distributions of pigments and plankton in the Atlantic Ocean between 50°N and 50°S. Data were quality assured by statistical methods, including regression of total chlorophyll a (TChla) versus accessory pigments (AP) and comparison of the AMT-TChla with contemporary SeaWiFS-TChla (cruises AMT-05 to -17). Comparisons of province-mean TChla (±SD) for in situ and satellite data showed good agreement for each cruise. ‘Taxa-specific’ pigments were used to define phytoplankton functional types (PFTs) for each of the biogeochemical provinces along the AMT. Pigment ratios (e.g. TChla/AP) were analysed for each cruise and for each province as indices (characteristic properties) of particular PFTs. Mostly robust positive correlations were observed between TChla and pigment ratios for different PFTs, for some provinces and most cruises. These were consistent with previous observations. Generally there were no significant trends of mean TChla or pigment ratios within provinces over the period 1995–2005, although the previously reported perturbation due to the 1997–1998 ENSO was evident.

Changes in plankton size structure and composition, during the generation of a phytoplankton bloom, in the central Cantabrian sea

Six stations situated on a transect perpendicular to the coast were sampled eight consecutive times in the central Cantabrian Sea, during February – March of 2005. A contrast was observed in the timing, magnitude and size structure of a phytoplankton bloom between coastal and oceanic stations, probably due to differences in the depth and mixing of the water column. The increase of biomass during the bloom occurred through the addition of “new” size classes of larger cells. An increase of small particle biomass was also observed at oceanic stations. In view of the results, it is proposed that at coastal stations, improved environmental conditions (nutrients and light) enhanced productivity and increased the number of both small and large cells. Because predation susceptibility is related to size, only large diatoms were able to escape from the predatory pressure exerted by microzooplankton. The results obtained indicate that imaging technology, combined with automatic recognition techniques, constitutes a powerful approach to describe plankton distributions at a fine temporal scale.