Andre Rochon

Andre Rochon
Université du Québec à Rimouski UQAR | uqar · Institut des Sciences de la Mer de Rimouski (ISMER)

Doctor of Philosophy

About

156
Publications
39,321
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6,502
Citations
Citations since 2017
35 Research Items
2617 Citations
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20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500

Publications

Publications (156)
Article
We use pollen and dinocyst assemblages from three sedimentary sequences of the San Jorge Gulf (SJG) to document the vegetation history of the extra-Andean/eastern Patagonia (Argentina), and the latitudinal variations of the Southern Westerly Wind Belt (SWWB) in relation with ocean changes during the Late Pleistocene and Holocene. Our results sugges...
Article
The expected increase of shipping activities in the Canadian Arctic is predicted to enhance potential introductions of non-indigenous species (NIS), including dinoflagellate taxa, which may have important ecological and economic impacts once released in a new environment. The lack of information about native species represents an obstacle in detect...
Presentation
Climate change may enhance the occurrence of harmful algal events (HAEs) in the Arctic Ocean (AO). While a certain number of HAEs have already been recorded in the AO, we lack a comprehensive knowledge of the spatial and temporal trends of these events over the last 150 years. To do so, we build a comprehensive database that compiles as many data a...
Article
Full-text available
The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables were measured across seven shelf–basin transects (south–north)...
Article
A box core and a trigger weight core were recovered from the Mackenzie Slope (Canadian Beaufort Sea) and combined into a composite sequence (AMD0214‐03BC/TWC: 03CS) to investigate dinocyst assemblages and the mineralogical and geochemical compositions. This allowed the estimation of sea‐surface conditions and documentation of changes in detrital in...
Article
Full-text available
The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon Fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north)...
Article
The sediment dynamics and the long-term evolution of intertidal environments depend on the erosion threshold, which is often increased by microbial biofilms. Intertidal biostabilization has been well studied in temperate and subtropical environments, but little is known for subarctic conditions with strong seasonal changes in vegetation cover and s...
Article
Spatial and temporal trends of marine harmful algal events in Canada over the last three decades were examined using data from the Harmful Algal Event Database (HAEDAT). This database contains the most complete record of algal blooms, phycotoxins and shellfish harvesting area closures in Canada since 1987. This 30-year review of 593 Canadian HAEDAT...
Article
This paper analyzes the distribution patterns of pollen and spore assemblages in modern surface sediments recovered from the bottom of the San Jorge Gulf (SJG) and from offshore sites, in relation to the location of different phytogeographic provinces surrounding the SJG, including the distant forest from southwestern Patagonia. Results reveal that...
Article
Full-text available
The mineralogical and geochemical compositions of three sediment cores from the northwestern Greenland continental margin (AMD14‐204, AMD14‐210) and Kane Basin (AMD14‐Kane2B) were investigated using quantitative X-ray diffraction (qXRD) and X-ray fluorescence (ED-XRF) in order to document the impact of ice-ocean interactions on the sediment provena...
Article
Organic-walled resting cysts of planktonic dinoflagellates occur commonly in modern marine sediment where they represent, with rare exceptions, the only geologically preservable part of the life cycle. Although many species do not produce fossilizable resting cysts, upper Quaternary sediments contain a diverse cyst record that is used frequently fo...
Article
Palynological analyses of 60 surface sediment samples from West Greenland margin revealed high concentrations of dinoflagellate cysts (dinocysts), particularly in the Disko Bugt area, where they reach >10⁴ cysts g⁻¹. Dinocyst assemblages are characterized by a relatively high species diversity and are dominated by Operculodinium centrocarpum, cysts...
Article
We present a new version of the standardized Northern Hemisphere “modern” dinoflagellate cyst (“dinocyst”) database, which includes abundances of 71 taxa at 1968 sites across the Northern Hemisphere, cross-referenced with 17 environmental parameters extracted mostly from the 2013 World Ocean Atlas. Several taxa with tropical to warm temperate affin...
Article
Dinoflagellate resting cysts with rare exception produce the only discrete link between the biology of extant dinoflagellate species and their fossil record. The geological preservability of such cysts allows them to be used for quantitative paleoecological reconstructions, especially in the Quaternary, and for biostratigraphy and the calibration o...
Article
This paper examines the distribution of 91 modern dinoflagellate cyst taxa from 3636 locations across the world's oceans. Patterns of distributions among the taxa included bi-polarity, cosmopolitan, northern versus southern hemispheres, and geographically restricted. Of the 91 taxa, three dominate these 3636 assemblages at the global scale, Brigant...
Poster
Full-text available
During the Late Miocene, the Caspian Sea was part of the brackish-marine Paratethyan Sea extending from Asia to eastern Europe during the ‘Pontian’ regional stage, before becoming a predominantly isolated lake basin from Pliocene to Holocene time. Distinctive organic-walled dinoflagellate cysts (dinocysts) with wing-like morphological features have...
Article
Full-text available
Thalassiphora and other large “winged” dinoflagellate cysts common in Oligocene–Pliocene stratified epicontinental seas display morphological variation greater than the plasticity of extant taxa, thereby raising questions about causes. This variation has been attributed to either directed ontogeny in response to salinity or oxygen gradients or to e...
Article
Full-text available
Miocene to modern sediments of the Ponto-Caspian basins and Mediterranean Sea are uniquely distinguished by presence of gonyaulacacean cysts with ellipsoid to cruciform endocysts and highly variable ectocystal features, including pterate (wing-like) and galeate (helmet-like) outer wall layers. The term cruciform is defined to indicate cysts with co...
Article
Full-text available
The use of dinoflagellate cyst assemblages as a tool for palaeo-environmental reconstructions strongly relies on the robustness of cyst identification and existing information on the distribution of the different species. To this purpose, we propose a functional key for the identification of Pliocene and Quaternary Spiniferites bearing intergonal p...
Article
In marine sediments of late Cenozoic age, Spiniferites is a very common genus of dinoflagellate cysts (dinocysts). Despite some taxonomical ambiguities due to large range of morphological variations within given species and convergent morphologies between different species, the establishment of an operational taxonomy permitted to develop a standar...
Article
Full-text available
We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly desc...
Article
Full-text available
The presence of upwelling systems and oceanic fronts makes the Southwest Atlantic Ocean a region of high primary productivity. These same conditions are present in San Jorge Gulf (SJG) along the southern Argentinian coast, where dinoflagellates and diatoms dominate primary production. The distribution of these microorganisms, including the cysts pr...
Article
The northeastern Baffin Bay continental margin, which experiences high sediment accumulation rates, is an excellent location to study Holocene sedimentary variations. However, it is often difficult to obtain reliable chronologies of the sediment archives using traditional methods (δ¹⁸O and radiocarbon) due to specific oceanographic conditions (e.g....
Article
Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp. is erected to accommodate this species. Pentaplacodinium saltonense differs from Protoceratium reticulatum (Claparède et Lac...
Article
We present here the first study on the role of ship traffic in the introduction of potentially harmful and/or non-indigenous species in the port of Annaba (Algeria). A total of 25 ships of two different types (general cargo and bulk carriers) were sampled and separated into two categories: oceanic and Mediterranean ships. We estimated propagule pre...
Article
Full-text available
Ballast water is a major vector of non-indigenous species introductions world-wide. Our understanding of population dynamics of organisms entrained in ballast is largely limited to studies of zooplankton and phytoplankton. Bacteria are more numerous and diverse than zooplankton or phytoplankton, yet remain comparatively understudied. We apply a met...
Poster
Full-text available
The preliminary results presented in this poster strengthened the idea of Chlorophyll a as an index parameter for sediment stability in intertidal areas. There is a positive correlation between Tau(crit) and organic matter content (measured by loss on ignition) as well as between Tau(crit) and chl a especially for high marsh zone.
Article
Full-text available
Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr,...
Article
Six cores, each approximately 10 m long, of late Pleistocene to Holocene age were studied from the Emba Delta region in the north-eastern Caspian Sea. Radiocarbon dates provide ages within the range of 47,820 to 12,020 cal BP for the middle sections, and for post-1950 close to surface. The ages fall within Marine Isotope Stage (MIS) 3, MIS 2 and MI...
Article
Full-text available
Estimates of propagule pressure in invasion biology are often unavailable due to widespread use of proxy variables, leading to uncertainty in absolute introduction effort of marine non-indigenous species (NIS). We present a first estimate of absolute propagule pressure (probability distributions of the total number of individuals introduced per rel...
Article
As polynyas are often used around the globe as a window on tomorrow's marine polar ecosystems, this study presents reconstructions of primary production and sea-surface conditions near the North Water polynya, since ~ 1560 CE from palynological, isotopic and biomarker analyses of a sediment core. Quantitative reconstructions of sea-surface conditio...
Article
Full-text available
This study documents the past ~7000 years of Holocene climatic history for Labrador and Nunatsiavut, using a sedimentary sequence of more than 8 m retrieved in Nachvak fjord, one of the northernmost fjords of Nunatsiavut. Using a multi-proxy approach combining a solid Accelerator Mass Spectrometry (AMS)-14C chronology and the fossil assemblages of...
Article
Full-text available
This study aimed at reconstructing past climatic and environmental conditions of a poorly known and documented subarctic region, the Nunatsiavut (northern Labrador). A multi-proxy approach was chosen, using fossil dinoflagellate cysts, diatoms and pollen from sediment cores taken into three fjords (Nachvak 59°N; Saglek 58.5°N; Anaktalak 56.5°N). It...
Chapter
The reduction, and ultimately the disappearance, of sea ice enhances the warming response of high latitude oceans through a positive feedback loop related to lessening of the heat reflected from ice. In theory, the more sea ice melts, the more rapidly the Arctic will warm. Computer models predict that continued global climate warming may lead to a...
Chapter
Full-text available
Dinoflagellates occur in most aquatic environments and constitute an important part of primary productivity. During their life cycle, some dinoflagellates produce organic-walled cysts (or dinocysts) that fossilize in sediment and are prepared for microscopic observation following palynological procedures. The dinoflagellates producing fossilizable...
Conference Paper
The broadly used microphotogrammetric method can be applied for morphological analysis of dinoflagellates by using scanning electron microscopy (SEM) or optical photography (OP) images. In order to maximise the photographic coverage of the specimens, two methods were tested 1) using SEM micrographs by rotating and tilting the SEM’s stage 2) using O...
Conference Paper
A new method is described here for high-resolution dinoflagellate analysis using Computer Assisted Tomography (CAT), or CAT- scanning. The insufficient radiodensity of dinoflagellate requires the use of a radiopaque stain or coating for such analysis. Consequently, two techniques were tested in order to make dinoflagellates radiopaque: 1) staining...
Conference Paper
The broadly used microphotogrammetric method can be applied for morphological analysis of dinoflagellates by using scanning electron microscopy (SEM) or optical photography (OP) images. In order to maximise the photographic coverage of the specimens, two methods were tested 1) using SEM micrographs by rotating and tilting the SEM’s stage 2) using O...
Article
Full-text available
Sea ice cover extent expressed in terms of mean annual concentration was reconstructed from the application of the modern analogue technique to dinocyst assemblages. The use of an updated database, which includes 1492 sites and 66 taxa, yields sea ice concentration estimates with an accuracy of ±1.1/10. Holocene reconstructions of sea ice cover wer...
Article
Round brown spiny cysts constitute a morphological group common in high latitude dinoflagellate cyst assemblages. The dinoflagellate cyst Islandinium minutum (Harland et Reid) Head, Harland et Matthiessen is the main paleoecological indicator of seasonal sea‐ice cover in the Arctic. Despite the importance of this cyst in paleoceanographical studies...
Article
Full-text available
Recent empirical and statistical evidence suggest that propagule pressure (i.e., number of individuals introduced per event, and the number and frequency of events) and colonization pressure (i.e., number of species released per event, and the number and frequency of events) are of vital importance to invasion success. To explore possible changes i...
Article
Full-text available
Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organic-walled dinoflagellate cy...
Conference Paper
Full-text available
Organic walled dinoflagellates (dinocysts), which occur in a wide range of environmental conditions including polar areas, were used to reconstruct sea ice cover based on the application of the modern analogue technique (MAT). Sea ice cover is expressed in terms of seasonal extent of sea ice cover (months per year with more than 50% of concentratio...
Article
1. The abundances and diversity of dinoflagellate cysts (including non-indigenous or harmful species) in ballast sediments were examined for the east and west coasts and the Great Lakes, to assess the potential invasion risk for these organisms and to determine similarity across regions. 2. In total, 147 ships were sampled, distributed among three...
Data
Full-text available
1. The abundances and diversity of dinoflagellate cysts (including non-indigenous or harmful species) in ballast sediments were examined for the east and west coasts and the Great Lakes, to assess the potential invasion risk for these organisms and to determine similarity across regions. 2. In total, 147 ships were sampled, distributed among three...
Data
1. The abundances and diversity of dinoflagellate cysts (including non-indigenous or harmful species) in ballast sediments were examined for the east and west coasts and the Great Lakes, to assess the potential invasion risk for these organisms and to determine similarity across regions. 2. In total, 147 ships were sampled, distributed among three...
Article
Full-text available
Round brown spiny dinoflagellate cysts from high latitudes of the Northern Hemisphere have been examined in order to define criteria for their determination during routine counts. The round brown spiny cysts belong to several taxa including the paleontological genera Echinidinium and Islandinium and the biological genera Oblea, Polykrikos, and Prot...
Chapter
The study of dinoflagellates and their cysts has been ongoing for the last c. 250 years following the pioneering work of the early, passionate researchers who first described them with rudimentary microscopes. The quality of modern microscopes and other laboratory equipment, coupled with enhanced computer capabilities, has extended the frontiers of...
Data
Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organicwalled dinoflagellate cys...
Article
Full-text available
Dinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct sea-surface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a dated 36 cm-long core collected...
Article
We report a large cyst bed of the potentially toxic and bloom-forming dinoflagellate Alexandrium tamarense species complex in bottom sediments from the port of Halifax, Nova Scotia, Canada. The average cyst concentrations of that species ranged from 4033±2647 to 220872±148086cystsg(-1) of dry sediments and the highest concentrations were found near...
Article
Full-text available
Canada’s IPY program funded seven marine projects spanning the North American Arctic. Work embraced oceanography, air-sea interactions, storm response, paleo-climate and trace-element chemistry. Notable findings are emerging. Conditions in the Beaufort were unusual in 2007, with very high air pressure bringing strong winds, rapid ice drift, thin wi...
Article
Process length variation of cysts of the dinoflagellate Protoceratium reticulatum (Claparède et Lachmann) Bü tschli in surface sediments from the North Pacific was investigated. The average process length showed a significant inverse relation to annual seawater density: s t annual ¼ À0.8674 Â average process length þ 1029.3 (R 2 ¼ 0.84), with a sta...
Article
Full-text available
Dinoflagellate cyst (dinocyst) assemblages have been widely used over the Arctic Ocean to reconstruct sea-surface parameters on a quantitative basis. Such reconstructions provide insights into the role of anthropogenic vs natural forcings in the actual climatic trend. Here, we present the palynological analysis of a 36 cm-long core collected from t...
Article
Full-text available
Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms,...
Article
Full-text available
We examined the risk of introduction associated with potentially toxic or otherwise harmful algae (HA) or nonindigenous species (NIS) of dinoflagellates in ballast water from 63 commercial ships visiting ports of eastern Canada in 2007–2009. Ship categories included transoceanics undergoing ballast water exchange (BWE) and coastal ships with or wit...
Article
Full-text available
In order to document long-term climate cycles and predict future climate trends for the Arctic, geological re-cords archived in ocean sediments can help establish the link between historical and pre-historical sea-surface parameters. Dinoflagellate cysts (dinocysts) are used as proxy indicators of sea-surface parameters (temperature, salinity, sea-...
Article
The macromolecular composition of dinoflagellate cyst walls is poorly understood and is usually referred to as ‘sporopollenin-like’. We have carried out micro-Fourier transform infra red (micro-FTIR) analysis of chemically untreated sediment-derived and enzymatically and chemically purified culture-derived L. polyedrum cyst walls, which suggests an...
Article
Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organicwalled dinoflagellate cys...
Conference Paper
Full-text available
Export Date: 6 February 2013, Source: Scopus, Article in Press
Article
Late Holocene paleoceanography and climate variability of the Southeastern Beaufort Sea (Canadian Arctic) have been investigated on the basis of sedimentary cores collected over the Mackenzie Slope. Piston, trigger and box cores were sampled at station 803 in 2004 aboard the CCGS Amundsen at 218 m water depth. The chronology of the piston core is c...
Article
Full-text available
Dinoflagellates are unicellular protists that produce a cyst (dinocyst) as part of their life cycle. The cyst wall of many species is composed of highly resistant organic matter. Dinocysts are thus routinely recovered in marine sediments and occur in high number along the continental margins of the world oceans notably in high latitude environments...
Data
Full-text available
The presence and abundance of non-indigenous, and/or harmful or toxic dinoflagellate species in ballast sediments is examined for 65 cargo ships visiting ports on the East coast of Canada, as part of the Canadian Aquatic Invasive Species Network (CAISN). Ships visiting several ports in the provinces of Quebec, New Brunswick and Nova Scotia were sam...
Article
Full-text available
The presence and abundance of non-indigenous, and/or harmful or toxic dinoflagellate species in ballast sediments is examined for 65 cargo ships visiting ports on the East coast of Canada, as part of the Canadian Aquatic Invasive Species Network (CAISN). Ships visiting several ports in the provinces of Quebec, New Brunswick and Nova Scotia were sam...
Article
Full-text available
Geochemical and micropaleontological analyses of Labrador Sea sediments allowed us to intercalibrate indicators of paleoproductivity and paleofluxes of carbon and to reconstitute biogeochemical fluxes, notably in relation to deep sea circulation changes (Western Boundary Undercurrent and North Atlantic Deep Water). Linear or logarithmic relations a...