Preface: Deep Sea Research Part II: Topical Studies in Oceanography

Esther Garcés; Marina Montresor; Jane Lewis; Karin Rengefors; Donald M. Anderson; Hartmut Barth

doi:10.1016/j.dsr2.2010.01.002

Preface: Deep Sea Research Part II: Topical Studies in Oceanography

Esther Garcés, Marina Montresor, Jane Lewis, Karin Rengefors, Donald M. Anderson, Hartmut Barth

UHI Shetland

Research output: Contribution to journal › Editorial › peer-review

8 Citations (Scopus)

Abstract

This special journal issue is a compilation of papers that derive from the collaborative project called SEED (Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species.

Original language	English
Pages (from-to)	159-161
Number of pages	3
Journal	Deep-Sea Research Part II: Topical Studies in Oceanography
Volume	57
Issue number	3-4
DOIs	https://doi.org/10.1016/j.dsr2.2010.01.002
Publication status	Published - 1 Feb 2010

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@article{1f9f333c44a540c1a6a8289c8afe02d6,

title = "Preface: Deep Sea Research Part II: Topical Studies in Oceanography",

abstract = "This special journal issue is a compilation of papers that derive from the collaborative project called SEED (Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species.",

author = "Esther Garc{\'e}s and Marina Montresor and Jane Lewis and Karin Rengefors and Anderson, {Donald M.} and Hartmut Barth",

note = "Funding Information: Garces Esther Garc{\'e}s a ⁎ [email protected] Marina Montresor b Jane Lewis c Karin Rengefors d Donald M. Anderson e Hartmut Barth f a Departament de Biologia Marina i Oceanografia, Institut de Ci{\`e}ncies del Mar, P. Mar{\'i}tim de la Barceloneta, 37-49, E08003 Barcelona, Spain b Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy c School of Life Sciences, University of Westminster, 115, New Cavendish Street, London W1W 6U, United Kingdom d Limnology, Departament of Ecology, Ecology Building, Lund University, SE-22362 Lund, Sweden e Woods Hole Oceanographic Institution, Biology Department Mail Stop 32, Redfield 332, Woods Hole MA 02543-1049, USA f European Commission, Directorate General for Research, Directorate I: Environment, B–1049 BRUSSELS, Belgium ⁎ 93 2309613; fax: +34 93 2309555. ⁎ Corresponding author. Tel.: +34 This special journal issue is a compilation of papers that derive from the collaborative project called SEED ( Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them ), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species. The parent project to SEED was LIFEHAB, an EU project that brought international specialists in life cycle research together at a workshop in Mallorca, Spain in 2001 ( Garc{\'e}s et al., 2002 ). That meeting discussed current methodologies and knowledge of life cycle stages and their dynamics, and proposed research recommendations to help resolve key impediments to progress. One of the main conclusions of LIFEHAB was that while great scientific effort has been devoted to the study of the planktonic stages of HAB species, our knowledge of other life stages was limited, and we were particularly ignorant of the diverse physiologies of benthic stages and the factors that drive the transformations between the benthic and planktonic phases of life. Indeed the details of the complete life cycle of many of the bloom forming species were unknown or very poorly characterized at the time. The extensive LIFEHAB discussions highlighted a number of research needs common to all algal groups, as well as specific requirements related to distinct algal divisions. A subsequent development was the recognition of the importance of scientific cooperation and exchange between the European Commission (EC) and the NSF. These entities signed an agreement in October 2001 to foster collaboration, with HABs identified as one of several topics of common interest. In September 2002, the EC Environment and Sustainable Development Programme and the US NSF jointly funded a workshop in Trieste (Italy) to bring together scientists from both sides of the Atlantic to collectively assess the state of HAB science, to identify gaps in our knowledge, and to develop an international plan for cooperative comparative studies. Subsequently, under the Biodiversity and Marine Ecosystems theme of the European 6th RTD Framework Programme the need for and plans to implement a joint EU–US programme were articulated. Recognizing this funding opportunity and the importance of an intercontinental exchange of knowledge in this area of research, several of the participants of LIFEHAB joined together to conceive a collaborative research proposal that included investigators and research elements from both sides of the Atlantic. Successful proposals were written to the EC and to the NSF, and SEED was thereby established. The overall objective of SEED was to improve and extend our understanding of the transitions among HAB life history stages in order to identify the genetic, environmental, and physiological factors that regulate those transitions. This can lead to identification of the relative importance of anthropogenic vs. natural causes for HABs and the integration of this knowledge into existing and future numerical models of HAB population dynamics. This in turn would lead to improved prediction, mitigation, and management strategies. The approach of SEED was that of “comparative systems,” consistent with the GEOHAB framework (GEOHAB is an international program on the ecology and oceanography of HAB species, co-sponsored by the Intergovernmental Oceanographic Commission and SCOR – the Scientific Committee on Oceanic Research). It thus investigated species of many different types, as well as a variety of habitats and ecosystems, ranging from brackish and freshwater to marine systems, and covering a broad range of species belonging to different algal classes. SEED research was multifaceted, combining field studies, laboratory experiments, and modeling. This issue represents the partial output of the SEED project. The contributions are broadly based, but they all share the common theme of life cycles as a critical element of HAB dynamics. Some of the contributions of this program can be summarized as follows: • The correct identification at the species level of vegetative cells and cysts is a fundamental requirement in ecological research. However some species can be differentiated only through minor morphological details, and their resting stages often share similar morphology. To overcome these problems, molecular methods (e.g., quantitative PCR) were applied in field studies, providing reliable and fast identification tools that allow discrimination between closely related species, thus facilitating large scale surveys ( Erdner et al., 2010 ; Penna et al., 2010 ; Touzet et al., 2010 ). Differences in DNA content among closely related species have been quantified by flow cytometry, showing that this character can be used to distinguish cryptic or pseudo-cryptic dinoflagellate taxa ( Figueroa et al., 2010 ). The Alexandrium tamarense- species complex includes different genotypes with distinct geographic distributions. Successful mating was obtained between toxic Group I and nontoxic Group III isolates but these hybrids were not viable ( Brosnahan et al., 2010 ). These results have important scientific and practical implications. Not only can this information help to explain the existing boundaries and extent of overlap between different Alexandrium strains and populations, but toxic Group I blooms might be mitigated by the introduction of nontoxic Group III populations. • The mating systems of dinoflagellates might be more complex than previously known; in fact crossing experiments carried out with multiple strains of Gymnodinium catenatum showed that both homothallism and heterothallism co-occur in this species ( Figueroa et al., 2010 ). • In diatoms, sexual reproduction is linked to the formation of cells of maximum size to circumvent the progressive cell size reduction that occurs during mitotic division. A simultaneous and massive sexual event involving two Pseudo-nitzschia species has been recorded for the first time in the natural environment ( Sarno et al., 2010 ). Auxosporulation seems to be restricted to a short time interval and this – together with the relative paucity of sexual stages in the populations - might account for the shortage of records of sex in planktonic diatoms . • The life cycle of several harmful species across different lineages includes benthic resting stages, short-lived pellicle cysts (whose confusing terminology was re-defined by Bravo et al., 2010a ) and planktonic vegetative cells; the alternation between these life stages has profound implications for population dynamics. Cyst assemblages in surface sediments represent a temporally integrated repertoire of species diversity, and cyst seedbeds provide baseline information for monitoring purposes, to depict geographic patterns of harmful species, and to detect the introduction of new species ( Rubino et al., 2010 ; Olli & Trunov, 2010 ; Satta et al., 2010 ). • The spatial and temporal patterns of cells in the water column and cysts in the sediments provide information on the role that the alternation between the two stages can have in different species and in environments characterized by distinct physical and chemical physiognomies. For example, in a small and secluded Mediterranean harbour, the spatial distribution of Alexandrium minutum cysts in surface sediments is strongly influenced by seiche-induced currents, which seem to reduce cyst losses by reallocating them to the sediment surface, reducing their burial ( Angl{\`e}s et al., 2010 ). Similarly, cyst seedbeds in the coastal portion of the Ria de Vigo play a major role in inoculating Alexandrium minutum blooms. In contrast, this is not the case for the short-lived cysts of Gymnodinium catanatum , whose blooms seem to depend on the inoculum of motile populations from offshore waters following upwelling relaxation events ( Bravo et al., 2010b ). • Resting stages can play a crucial role in the population dynamics of cyanobacteria responsible for intense summer blooms in the Baltic Sea. Interestingly, different species show distinct life cycle strategies: Aphanizomenon flos-aquae is holoplanktonic, while Anabaena spp. is planktonic during summer, but overwinters as akinetes in the sediments. Nodularia spumigena blooms may originate from both sedimented akinetes and trichomes that overwinter in the water column ( Suikkanen et al., 2010 ). • Life cycle parameters can now be incorporated into numerical models that will enhance our understanding and our predictive capabilities. Estrada et al. (2010) discuss different kinds of models applied to Alexandrium minutum , highlighting the need to quantify short-term temporal variability of the different life stages, of the physical parameters, as well as detailed estimates of population growth and loss rates. At the start of SEED, there were many unknowns in these topic areas, and some of those have been resolved. Considerable work remains before us, however. For example: there are many species for which the life cycles need additional study and clarification; we still lack the ability to identify the factors that drive the transitionsbetween stages, and in particular, do not fully understand the triggers for sexuality and encystment; we need to use the new molecular and taxonomic skills developed here to explore biogeographic species boundaries and bloom dynamics; we need many more field studies of HABs that include detailed life cycle observations throughout, including mapping studies that document the distribution and abundance of benthic resting stages; we need to know what regulates the timing of blooms of the species that do not include benthic resting stages in their life cycle; our knowledge of life cycle dynamics needs to be incorporated into species-specific numerical models of bloom dynamics so that we better simulate the stages of initiation, maintenance, and decline; and we need to explore promising bloom mitigation strategies that are based on life history stages, such as the mating of toxic and non-toxic strains of the same species. The papers presented here are a significant, but early step in our exploration of HAB life history stages. We hope these contributions provide guidance and inspiration to those who carry these investigations forward, following the guiding principle expressed by the great pioneer in phytoplankton life cycle studies, H.A. von Stosch, who stated “You only know a species if you know its complete life cycle.” ",

year = "2010",

month = feb,

day = "1",

doi = "10.1016/j.dsr2.2010.01.002",

language = "English",

volume = "57",

pages = "159--161",

journal = "Deep-Sea Research Part II: Topical Studies in Oceanography",

issn = "0967-0645",

publisher = "Elsevier Ltd",

number = "3-4",

}

TY - JOUR

T1 - Preface

T2 - Deep Sea Research Part II: Topical Studies in Oceanography

AU - Garcés, Esther

AU - Montresor, Marina

AU - Lewis, Jane

AU - Rengefors, Karin

AU - Anderson, Donald M.

AU - Barth, Hartmut

N1 - Funding Information: Garces Esther Garcés a ⁎ [email protected] Marina Montresor b Jane Lewis c Karin Rengefors d Donald M. Anderson e Hartmut Barth f a Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, P. Marítim de la Barceloneta, 37-49, E08003 Barcelona, Spain b Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy c School of Life Sciences, University of Westminster, 115, New Cavendish Street, London W1W 6U, United Kingdom d Limnology, Departament of Ecology, Ecology Building, Lund University, SE-22362 Lund, Sweden e Woods Hole Oceanographic Institution, Biology Department Mail Stop 32, Redfield 332, Woods Hole MA 02543-1049, USA f European Commission, Directorate General for Research, Directorate I: Environment, B–1049 BRUSSELS, Belgium ⁎ 93 2309613; fax: +34 93 2309555. ⁎ Corresponding author. Tel.: +34 This special journal issue is a compilation of papers that derive from the collaborative project called SEED ( Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them ), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species. The parent project to SEED was LIFEHAB, an EU project that brought international specialists in life cycle research together at a workshop in Mallorca, Spain in 2001 ( Garcés et al., 2002 ). That meeting discussed current methodologies and knowledge of life cycle stages and their dynamics, and proposed research recommendations to help resolve key impediments to progress. One of the main conclusions of LIFEHAB was that while great scientific effort has been devoted to the study of the planktonic stages of HAB species, our knowledge of other life stages was limited, and we were particularly ignorant of the diverse physiologies of benthic stages and the factors that drive the transformations between the benthic and planktonic phases of life. Indeed the details of the complete life cycle of many of the bloom forming species were unknown or very poorly characterized at the time. The extensive LIFEHAB discussions highlighted a number of research needs common to all algal groups, as well as specific requirements related to distinct algal divisions. A subsequent development was the recognition of the importance of scientific cooperation and exchange between the European Commission (EC) and the NSF. These entities signed an agreement in October 2001 to foster collaboration, with HABs identified as one of several topics of common interest. In September 2002, the EC Environment and Sustainable Development Programme and the US NSF jointly funded a workshop in Trieste (Italy) to bring together scientists from both sides of the Atlantic to collectively assess the state of HAB science, to identify gaps in our knowledge, and to develop an international plan for cooperative comparative studies. Subsequently, under the Biodiversity and Marine Ecosystems theme of the European 6th RTD Framework Programme the need for and plans to implement a joint EU–US programme were articulated. Recognizing this funding opportunity and the importance of an intercontinental exchange of knowledge in this area of research, several of the participants of LIFEHAB joined together to conceive a collaborative research proposal that included investigators and research elements from both sides of the Atlantic. Successful proposals were written to the EC and to the NSF, and SEED was thereby established. The overall objective of SEED was to improve and extend our understanding of the transitions among HAB life history stages in order to identify the genetic, environmental, and physiological factors that regulate those transitions. This can lead to identification of the relative importance of anthropogenic vs. natural causes for HABs and the integration of this knowledge into existing and future numerical models of HAB population dynamics. This in turn would lead to improved prediction, mitigation, and management strategies. The approach of SEED was that of “comparative systems,” consistent with the GEOHAB framework (GEOHAB is an international program on the ecology and oceanography of HAB species, co-sponsored by the Intergovernmental Oceanographic Commission and SCOR – the Scientific Committee on Oceanic Research). It thus investigated species of many different types, as well as a variety of habitats and ecosystems, ranging from brackish and freshwater to marine systems, and covering a broad range of species belonging to different algal classes. SEED research was multifaceted, combining field studies, laboratory experiments, and modeling. This issue represents the partial output of the SEED project. The contributions are broadly based, but they all share the common theme of life cycles as a critical element of HAB dynamics. Some of the contributions of this program can be summarized as follows: • The correct identification at the species level of vegetative cells and cysts is a fundamental requirement in ecological research. However some species can be differentiated only through minor morphological details, and their resting stages often share similar morphology. To overcome these problems, molecular methods (e.g., quantitative PCR) were applied in field studies, providing reliable and fast identification tools that allow discrimination between closely related species, thus facilitating large scale surveys ( Erdner et al., 2010 ; Penna et al., 2010 ; Touzet et al., 2010 ). Differences in DNA content among closely related species have been quantified by flow cytometry, showing that this character can be used to distinguish cryptic or pseudo-cryptic dinoflagellate taxa ( Figueroa et al., 2010 ). The Alexandrium tamarense- species complex includes different genotypes with distinct geographic distributions. Successful mating was obtained between toxic Group I and nontoxic Group III isolates but these hybrids were not viable ( Brosnahan et al., 2010 ). These results have important scientific and practical implications. Not only can this information help to explain the existing boundaries and extent of overlap between different Alexandrium strains and populations, but toxic Group I blooms might be mitigated by the introduction of nontoxic Group III populations. • The mating systems of dinoflagellates might be more complex than previously known; in fact crossing experiments carried out with multiple strains of Gymnodinium catenatum showed that both homothallism and heterothallism co-occur in this species ( Figueroa et al., 2010 ). • In diatoms, sexual reproduction is linked to the formation of cells of maximum size to circumvent the progressive cell size reduction that occurs during mitotic division. A simultaneous and massive sexual event involving two Pseudo-nitzschia species has been recorded for the first time in the natural environment ( Sarno et al., 2010 ). Auxosporulation seems to be restricted to a short time interval and this – together with the relative paucity of sexual stages in the populations - might account for the shortage of records of sex in planktonic diatoms . • The life cycle of several harmful species across different lineages includes benthic resting stages, short-lived pellicle cysts (whose confusing terminology was re-defined by Bravo et al., 2010a ) and planktonic vegetative cells; the alternation between these life stages has profound implications for population dynamics. Cyst assemblages in surface sediments represent a temporally integrated repertoire of species diversity, and cyst seedbeds provide baseline information for monitoring purposes, to depict geographic patterns of harmful species, and to detect the introduction of new species ( Rubino et al., 2010 ; Olli & Trunov, 2010 ; Satta et al., 2010 ). • The spatial and temporal patterns of cells in the water column and cysts in the sediments provide information on the role that the alternation between the two stages can have in different species and in environments characterized by distinct physical and chemical physiognomies. For example, in a small and secluded Mediterranean harbour, the spatial distribution of Alexandrium minutum cysts in surface sediments is strongly influenced by seiche-induced currents, which seem to reduce cyst losses by reallocating them to the sediment surface, reducing their burial ( Anglès et al., 2010 ). Similarly, cyst seedbeds in the coastal portion of the Ria de Vigo play a major role in inoculating Alexandrium minutum blooms. In contrast, this is not the case for the short-lived cysts of Gymnodinium catanatum , whose blooms seem to depend on the inoculum of motile populations from offshore waters following upwelling relaxation events ( Bravo et al., 2010b ). • Resting stages can play a crucial role in the population dynamics of cyanobacteria responsible for intense summer blooms in the Baltic Sea. Interestingly, different species show distinct life cycle strategies: Aphanizomenon flos-aquae is holoplanktonic, while Anabaena spp. is planktonic during summer, but overwinters as akinetes in the sediments. Nodularia spumigena blooms may originate from both sedimented akinetes and trichomes that overwinter in the water column ( Suikkanen et al., 2010 ). • Life cycle parameters can now be incorporated into numerical models that will enhance our understanding and our predictive capabilities. Estrada et al. (2010) discuss different kinds of models applied to Alexandrium minutum , highlighting the need to quantify short-term temporal variability of the different life stages, of the physical parameters, as well as detailed estimates of population growth and loss rates. At the start of SEED, there were many unknowns in these topic areas, and some of those have been resolved. Considerable work remains before us, however. For example: there are many species for which the life cycles need additional study and clarification; we still lack the ability to identify the factors that drive the transitionsbetween stages, and in particular, do not fully understand the triggers for sexuality and encystment; we need to use the new molecular and taxonomic skills developed here to explore biogeographic species boundaries and bloom dynamics; we need many more field studies of HABs that include detailed life cycle observations throughout, including mapping studies that document the distribution and abundance of benthic resting stages; we need to know what regulates the timing of blooms of the species that do not include benthic resting stages in their life cycle; our knowledge of life cycle dynamics needs to be incorporated into species-specific numerical models of bloom dynamics so that we better simulate the stages of initiation, maintenance, and decline; and we need to explore promising bloom mitigation strategies that are based on life history stages, such as the mating of toxic and non-toxic strains of the same species. The papers presented here are a significant, but early step in our exploration of HAB life history stages. We hope these contributions provide guidance and inspiration to those who carry these investigations forward, following the guiding principle expressed by the great pioneer in phytoplankton life cycle studies, H.A. von Stosch, who stated “You only know a species if you know its complete life cycle.”

PY - 2010/2/1

Y1 - 2010/2/1

N2 - This special journal issue is a compilation of papers that derive from the collaborative project called SEED (Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species.

AB - This special journal issue is a compilation of papers that derive from the collaborative project called SEED (Life cycle transformations among HAB species, and the environmental and physiological factors that regulate them), funded by the European Union's Environment and Sustainable Development Research Programme (EU-FP6) and the US National Science Foundation (NSF). These emphasized the environmental, physiological, and genetic factors that influence transitions among life cycle stages of harmful microalgal species. Life cycle transitions are an integral aspect of harmful algal bloom (HAB) dynamics, yet when this project began, remarkably little was known of life cycle dynamics in those species.

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U2 - 10.1016/j.dsr2.2010.01.002

DO - 10.1016/j.dsr2.2010.01.002

M3 - Editorial

AN - SCOPUS:77649147284

SN - 0967-0645

VL - 57

SP - 159

EP - 161

JO - Deep-Sea Research Part II: Topical Studies in Oceanography

JF - Deep-Sea Research Part II: Topical Studies in Oceanography

IS - 3-4

ER -

Preface: Deep Sea Research Part II: Topical Studies in Oceanography

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