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Jonathan M. Waters - One of the best experts on this subject based on the ideXlab platform.
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northward range extension for Durvillaea poha bull kelp response to tectonic disturbance
Journal of Phycology, 2021Co-Authors: Felix Vaux, Ceridwen I. Fraser, Dave Craw, Jonathan M. WatersAbstract:Understanding the forces that shape species distributions is increasingly important in a fast-changing world. Although major disturbance events can adversely affect natural populations, they can also present new opportunities, for example by opening up habitat for colonization by other lineages. Following extensive geographic sampling, we use genomic data to infer a range extension following disturbance for an ecologically important intertidal macroalgal species. Specifically, we genotyped 288 southern bull kelp (Durvillaea) plants from 28 localities across central New Zealand. All specimens from the North Island were expected to be D. antarctica, but unexpectedly 10 samples from four sites were identified as D. poha. Extensive sampling from the northern South Island (105 samples at five locations) confirmed the absence of D. poha north of the Kaikōura Peninsula. The North Island specimens of D. poha therefore reveal a biogeographic disjunction, some 150 km northeast of the nearest (South Island) population of this species. Based on strong geographic correspondence between these North Island samples and historic disturbance, we infer that tectonic upheaval, particularly earthquake-generated landslides, likely extirpated local D. antarctica and created an opportunity for a northward range expansion event by D. poha. Close phylogenomic relationships between this new North Island population and South Island samples support a geologically recent northward expansion, rather than a deeper evolutionary origin. These findings indicate the potential of large-scale disturbances to facilitate sudden biogeographic range expansions, and they emphasize the ability of genomic analyses with fine-scale sampling to reveal long-lasting signatures of past disturbance, dispersal, and colonization.
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rafting dispersal in a brooding southern sea star asteroidea anasterias
Invertebrate Systematics, 2018Co-Authors: Jonathan M. Waters, Ceridwen I. Fraser, Tania M King, Christopher J GardenAbstract:Marine biogeographers have long speculated that macroalgal rafting presents a dispersal mechanism for brooding marine invertebrates of the Southern Ocean, but few direct observations of rafting by echinoderm taxa have been documented. Here we report rafting of the brooding benthic sea star Anasterias suteri, along with two mollusc taxa (Onithochiton neglectus – also a brooder – and Cantharidus roseus), on detached bull-kelp Durvillaea antarctica in Foveaux Strait, southern New Zealand. The rafting journey, intercepted at sea, likely lasted for 2–3 weeks and may have covered several hundred kilometres. We use DNA sequences, together with meteorological and prevailing oceanographic data, to infer the likely Fiordland (mainland) origins of the raft and its epifauna. This rafting dispersal mechanism provides an explanation for the broad (circum-subantarctic) but disjunct distribution of brooding Anasterias populations, and for the genetic connectivity observed between their populations.
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crossing the front contrasting storm forced dispersal dynamics revealed by biological geological and genetic analysis of beach cast kelp
Journal of the Royal Society Interface, 2018Co-Authors: Jonathan M. Waters, Ceridwen I. Fraser, Tania M King, Dave CrawAbstract:The subtropical front (STF) generally represents a substantial oceanographic barrier to dispersal between cold-sub-Antarctic and warm-temperate water masses. Recent studies have suggested that storm events can drastically influence marine dispersal and patterns. Here we analyse biological and geological dispersal driven by two major, contrasting storm events in southern New Zealand, 2017. We integrate biological and physical data to show that a severe southerly system in July 2017 disrupted this barrier by promoting movement of substantial numbers of southern sub-Antarctic Durvillaea kelp rafts across the STF, to make landfall in mainland NZ. By contrast, a less intense easterly storm (Cyclone Cook, April 2017) resulted in more moderate dispersal distances, with minimal dispersal between the sub-Antarctic and mainland New Zealand. These quantitative analyses of approximately 200 freshly beach-cast kelp specimens indicate that storm intensity and wind direction can strongly influence marine dispersal and landfall outcomes.
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a morphological and phylogenetic investigation into divergence among sympatric australian southern bull kelps Durvillaea potatorum and d amatheiae sp nov
Molecular Phylogenetics and Evolution, 2017Co-Authors: Xenia A Weber, Jonathan M. Waters, Graham J Edgar, Sam C Banks, Ceridwen I. FraserAbstract:Genetic analyses can reveal a wealth of hitherto undiscovered cryptic biodiversity. For co-occurring and morphologically similar species, the combination of molecular, ecological and morphological analyses provides an excellent opportunity for understanding some of the processes that can lead to divergence and speciation. The Australian endemic brown macroalga Durvillaea potatorum (Phaeophyceae) was examined with a combination of genetic and morphological approaches to confirm the presence of two separate species and to infer the processes that led to their divergence. A total of 331 individuals from 11 sites around coastal Tasmania were collected and measured in situ for a range of morphological and ecological characteristics. Tissue samples were also collected for each individual to allow genetic analyses using mitochondrial (COI) and nuclear (28S) markers. Genetic analyses confirmed the presence of two deeply divergent clades. The significant morphological differentiation, despite high levels of intra-lineage variability, further supported their recognition as distinct species. We describe a new species, D. amatheiae sp. nov., which is characterised by a narrower and proportionately shorter stipe, shorter total length, and higher number of stipitate lateral blades and branches than D. potatorum (sensu stricto). The occurrence of both species in sympatry along Tasmania's eastern and western coasts, as well as their contrasting patterns of haplotype diversity, supports a hypothesis of geographical isolation, allopatric speciation and subsequent secondary contact in response to sea level and ocean current change throughout the Pleistocene glaciation cycles. This research contributes to resolving the phylogenetic relationships, taxonomy and evolution of the ecologically keystone kelp genus Durvillaea.
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Durvillaea poha sp nov fucales phaeophyceae a buoyant southern bull kelp species endemic to new zealand
Phycologia, 2012Co-Authors: Ceridwen I. Fraser, Hamish G. Spencer, Jonathan M. WatersAbstract:Abstract Fraser C.I., Spencer H.G. and Waters J.M. 2012. Durvillaea poha sp. nov. (Fucales, Phaeophyceae): a buoyant southern bull-kelp species endemic to New Zealand. Phycologia 51: 151–156. DOI: 10.2216/11-47.1 Recent molecular and morphological research has demonstrated that the southern bull-kelp genus Durvillaea includes multiple as-yet-unnamed phylogenetic species. One of these, which has previously been recognised as genetically, morphologically and ecologically distinct (the ‘cape’ lineage of D. antarctica, endemic to the New Zealand region), is here described, and named Durvillaea poha sp. nov. Additional molecular analyses (28S sequence data) support the distinct status of this divergent lineage. No evidence of hybridisation among sympatric D. poha and D. antarctica has been observed.
Ceridwen I. Fraser - One of the best experts on this subject based on the ideXlab platform.
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northward range extension for Durvillaea poha bull kelp response to tectonic disturbance
Journal of Phycology, 2021Co-Authors: Felix Vaux, Ceridwen I. Fraser, Dave Craw, Jonathan M. WatersAbstract:Understanding the forces that shape species distributions is increasingly important in a fast-changing world. Although major disturbance events can adversely affect natural populations, they can also present new opportunities, for example by opening up habitat for colonization by other lineages. Following extensive geographic sampling, we use genomic data to infer a range extension following disturbance for an ecologically important intertidal macroalgal species. Specifically, we genotyped 288 southern bull kelp (Durvillaea) plants from 28 localities across central New Zealand. All specimens from the North Island were expected to be D. antarctica, but unexpectedly 10 samples from four sites were identified as D. poha. Extensive sampling from the northern South Island (105 samples at five locations) confirmed the absence of D. poha north of the Kaikōura Peninsula. The North Island specimens of D. poha therefore reveal a biogeographic disjunction, some 150 km northeast of the nearest (South Island) population of this species. Based on strong geographic correspondence between these North Island samples and historic disturbance, we infer that tectonic upheaval, particularly earthquake-generated landslides, likely extirpated local D. antarctica and created an opportunity for a northward range expansion event by D. poha. Close phylogenomic relationships between this new North Island population and South Island samples support a geologically recent northward expansion, rather than a deeper evolutionary origin. These findings indicate the potential of large-scale disturbances to facilitate sudden biogeographic range expansions, and they emphasize the ability of genomic analyses with fine-scale sampling to reveal long-lasting signatures of past disturbance, dispersal, and colonization.
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Concise review of the genus Durvillaea Bory de Saint-Vincent, 1825
Journal of Applied Phycology, 2020Co-Authors: Marcel Velásquez, Ceridwen I. Fraser, Wendy A. Nelson, Fadia Tala, Erasmo C. MacayaAbstract:The genus Durvillaea includes six currently accepted species, as well as two newly proposed species. Durvillaea spp. have a diplontic life cycle, lack a free-living gametophyte and have oogamous reproduction. All Durvillaea species require rocky substrate for attachment and wave-exposed environments. These “southern bull kelps” occur exclusively in the Southern Hemisphere and are important foundation species, in most cases controlling local community structure, influencing biodiversity, and providing food and habitat for other culturally and economically important species. Most species are non-buoyant and these have restricted geographic ranges, in some cases endemic to small oceanic islands. Buoyant members of the genus are more widespread, with one species ( Durvillaea antarctica ) found throughout the subantarctic, Chile, and New Zealand. This chapter summarizes the taxonomy, biology, and economic importance of Durvillaea species, with a focus on aspects relevant to their availability and productivity as crop plants. Systematics, distribution, ecology, life histories, population status, harvesting times, protection, management and chemical composition are covered. Much of the available data are for the species Durvillaea antarctica , D. willana , and D. potatorum . The techniques used in harvesting and the human uses of Durvillaea spp. (e.g., as food) are described, along with recommendations for harvest timing and methods.
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rafting dispersal in a brooding southern sea star asteroidea anasterias
Invertebrate Systematics, 2018Co-Authors: Jonathan M. Waters, Ceridwen I. Fraser, Tania M King, Christopher J GardenAbstract:Marine biogeographers have long speculated that macroalgal rafting presents a dispersal mechanism for brooding marine invertebrates of the Southern Ocean, but few direct observations of rafting by echinoderm taxa have been documented. Here we report rafting of the brooding benthic sea star Anasterias suteri, along with two mollusc taxa (Onithochiton neglectus – also a brooder – and Cantharidus roseus), on detached bull-kelp Durvillaea antarctica in Foveaux Strait, southern New Zealand. The rafting journey, intercepted at sea, likely lasted for 2–3 weeks and may have covered several hundred kilometres. We use DNA sequences, together with meteorological and prevailing oceanographic data, to infer the likely Fiordland (mainland) origins of the raft and its epifauna. This rafting dispersal mechanism provides an explanation for the broad (circum-subantarctic) but disjunct distribution of brooding Anasterias populations, and for the genetic connectivity observed between their populations.
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crossing the front contrasting storm forced dispersal dynamics revealed by biological geological and genetic analysis of beach cast kelp
Journal of the Royal Society Interface, 2018Co-Authors: Jonathan M. Waters, Ceridwen I. Fraser, Tania M King, Dave CrawAbstract:The subtropical front (STF) generally represents a substantial oceanographic barrier to dispersal between cold-sub-Antarctic and warm-temperate water masses. Recent studies have suggested that storm events can drastically influence marine dispersal and patterns. Here we analyse biological and geological dispersal driven by two major, contrasting storm events in southern New Zealand, 2017. We integrate biological and physical data to show that a severe southerly system in July 2017 disrupted this barrier by promoting movement of substantial numbers of southern sub-Antarctic Durvillaea kelp rafts across the STF, to make landfall in mainland NZ. By contrast, a less intense easterly storm (Cyclone Cook, April 2017) resulted in more moderate dispersal distances, with minimal dispersal between the sub-Antarctic and mainland New Zealand. These quantitative analyses of approximately 200 freshly beach-cast kelp specimens indicate that storm intensity and wind direction can strongly influence marine dispersal and landfall outcomes.
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a morphological and phylogenetic investigation into divergence among sympatric australian southern bull kelps Durvillaea potatorum and d amatheiae sp nov
Molecular Phylogenetics and Evolution, 2017Co-Authors: Xenia A Weber, Jonathan M. Waters, Graham J Edgar, Sam C Banks, Ceridwen I. FraserAbstract:Genetic analyses can reveal a wealth of hitherto undiscovered cryptic biodiversity. For co-occurring and morphologically similar species, the combination of molecular, ecological and morphological analyses provides an excellent opportunity for understanding some of the processes that can lead to divergence and speciation. The Australian endemic brown macroalga Durvillaea potatorum (Phaeophyceae) was examined with a combination of genetic and morphological approaches to confirm the presence of two separate species and to infer the processes that led to their divergence. A total of 331 individuals from 11 sites around coastal Tasmania were collected and measured in situ for a range of morphological and ecological characteristics. Tissue samples were also collected for each individual to allow genetic analyses using mitochondrial (COI) and nuclear (28S) markers. Genetic analyses confirmed the presence of two deeply divergent clades. The significant morphological differentiation, despite high levels of intra-lineage variability, further supported their recognition as distinct species. We describe a new species, D. amatheiae sp. nov., which is characterised by a narrower and proportionately shorter stipe, shorter total length, and higher number of stipitate lateral blades and branches than D. potatorum (sensu stricto). The occurrence of both species in sympatry along Tasmania's eastern and western coasts, as well as their contrasting patterns of haplotype diversity, supports a hypothesis of geographical isolation, allopatric speciation and subsequent secondary contact in response to sea level and ocean current change throughout the Pleistocene glaciation cycles. This research contributes to resolving the phylogenetic relationships, taxonomy and evolution of the ecologically keystone kelp genus Durvillaea.
Hamish G. Spencer - One of the best experts on this subject based on the ideXlab platform.
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Durvillaea poha sp nov fucales phaeophyceae a buoyant southern bull kelp species endemic to new zealand
Phycologia, 2012Co-Authors: Ceridwen I. Fraser, Hamish G. Spencer, Jonathan M. WatersAbstract:Abstract Fraser C.I., Spencer H.G. and Waters J.M. 2012. Durvillaea poha sp. nov. (Fucales, Phaeophyceae): a buoyant southern bull-kelp species endemic to New Zealand. Phycologia 51: 151–156. DOI: 10.2216/11-47.1 Recent molecular and morphological research has demonstrated that the southern bull-kelp genus Durvillaea includes multiple as-yet-unnamed phylogenetic species. One of these, which has previously been recognised as genetically, morphologically and ecologically distinct (the ‘cape’ lineage of D. antarctica, endemic to the New Zealand region), is here described, and named Durvillaea poha sp. nov. Additional molecular analyses (28S sequence data) support the distinct status of this divergent lineage. No evidence of hybridisation among sympatric D. poha and D. antarctica has been observed.
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Multigene phylogeny of the southern bull-kelp genus Durvillaea (Phaeophyceae: Fucales).
Molecular Phylogenetics and Evolution, 2010Co-Authors: Ceridwen I. Fraser, David J. Winter, Hamish G. Spencer, Jonathan M. WatersAbstract:Abstract Durvillaea (southern bull-kelp) is an economically and ecologically important brown algal genus that dominates many exposed, rocky coasts in the cold-temperate Southern Hemisphere. Of its five currently-recognized species, four are non-buoyant and restricted to the south-western Pacific, whereas one is both buoyant and widely distributed. Durvillaea has had an unsettled taxonomic history. Although its position within the brown algae (Phaeophyceae) has now been largely resolved through the use of molecular techniques, the taxonomic status of several Durvillaea species/morphotypes remains unresolved. Previous molecular phylogenetic studies of phaeophycean taxa have included few Durvillaea samples, and have consequently paid little or no attention to variation within this genus. The current study presents phylogenetic analyses of four genetic markers (mitchondrial: COI; chloroplast: rbcL; and nuclear: 18S and 28S) to resolve phylogenetic relationships within Durvillaea. Results support the monophyly of solid-bladed taxa D. willana, D. potatorum, and D. sp. A (an undescribed species from the Antipodes Islands), whereas the widespread, buoyant D. antarctica is paraphyletic, with solid-bladed D. chathamensis placed sister to a D. antarctica clade from northern NZ but within D. antarctica sensu lato. The phylogenetic and ecological diversity detected within D. antarctica indicate that it is a species complex of five deeply divergent clades. Under a phylogenetic species concept, Durvillaea can be interpreted as a complex of nine distinct evolutionary lineages, only one of which has an intercontinental distribution (‘subantarctic’ D. antarctica).
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systematics and phylogeny of a new cryptic species of diloma philippi mollusca gastropoda trochidae from a novel habitat the bull kelp holdfast communities of southern new zealand
Invertebrate Systematics, 2009Co-Authors: Hamish G. Spencer, Bruce A Marshall, Jonathan M. WatersAbstract:The seven currently recognised New Zealand species in the gastropod genus Diloma Philippi, 1845 are an important component of New Zealand’s littoral biodiversity across a range of intertidal habitats. A new cryptic species in this genus (Diloma Durvillaea, sp. nov.) is described largely on molecular grounds from exposed coasts of the South Island of New Zealand from Lyttelton south, as well as the Auckland Islands. The shell is very similar to D. arida (Finlay, 1926), differing subtly in having stronger spiral ribs and less extensive or no yellow spotting. Phylogenetic analysis of the mitochondrial cytochrome c oxidase I (COI) gene shows these two species are sister-taxa and are more distinct from each other (genetic distance 11.5%) than are the morphologically divergent sister-species D. subrostrata (Gray, 1835) and D. aethiops (Gmelin, 1791) (8.2%), also from New Zealand. The new species is found in a novel habitat for the genus, in the holdfasts and on the blades of the bull kelp, Durvillaea antarctica (Cham.) Har. (Phaeophyta), at the low-tide mark on exposed coasts, whereas D. arida occurs higher up on the shore, as well as in more sheltered situations.
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genetic and morphological analyses of the southern bull kelp Durvillaea antarctica phaeophyceae Durvillaeales in new zealand reveal cryptic species
Journal of Phycology, 2009Co-Authors: Ceridwen I. Fraser, Hamish G. Spencer, Jonathan M. WatersAbstract:Many macroalgae exhibit considerable intraspecific morphological variation, but whether such variation reflects phenotypic plasticity or underlying genetic differences is often poorly understood. We quantified both morphological and genetic variation of 96 plants from seven field sites across eastern South Island, New Zealand, to assess genetic differences between morphotypes of the southern bull kelp Durvillaea antarctica (Cham.) Har. Consistent DNA sequence differentiation across mitochondrial, plastid, and nuclear loci was correlated with two broadly sympatric morphotypes: “cape” and “thonged.” These ecologically, morphologically, and genetically distinct bull-kelp lineages were previously considered to be environmentally determined phenotypes with no underlying genetic basis. Interestingly, the sheltered “cape” lineage appears essentially genetically uniform across its South Island range, whereas the exposed “thonged” lineage exhibits marked phylogeographic structure across its range. Results suggest that D. antarctica in New Zealand comprises two reproductively isolated species.
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Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum
2009Co-Authors: Ceridwen I. Fraser, Hamish G. Spencer, Raisa Nikula, Jonathan M. WatersAbstract:The end of the Last Glacial Maximum (LGM) dramatically reshaped temperate ecosystems, with many species moving poleward as temperatures rose and ice receded. Whereas reinvading terrestrial taxa tracked melting glaciers, marine biota recolonized ocean habitats freed by retreating sea ice. The extent of sea ice in the Southern Hemisphere during the LGM has, however, yet to be fully resolved, with most palaeogeographic studies suggesting only minimal or patchy ice cover in subantarctic waters. Here, through population genetic analyses of the widespread Southern Bull Kelp (Durvillaea antarctica), we present evidence for persistent ice scour affecting subantarctic islands during the LGM. Using mitochondrial and chloroplast genetic markers (COI; rbcL) to genetically characterize some 300 kelp samples from 45 Southern Ocean localities, we reveal a remarkable pattern of recent recolonization in the subantarctic. Specifically, in contrast to the marked phylogeographic structure observed across coastal New Zealand and Chile (10-to 100-km scales), subantarctic samples show striking genetic homogeneity over vast distances (10,000-km scales), with a single widespread haplotype observed for each marker. From these results, we suggest that sea ice expanded further and ice scour during the LGM impacted shallow-water subantarctic marine ecosystems more extensively than previously suggested. Durvillaea antarctica ͉ genetic ͉ phylogeography ͉ raf
Fadia Tala - One of the best experts on this subject based on the ideXlab platform.
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Concise review of the genus Durvillaea Bory de Saint-Vincent, 1825
Journal of Applied Phycology, 2020Co-Authors: Marcel Velásquez, Ceridwen I. Fraser, Wendy A. Nelson, Fadia Tala, Erasmo C. MacayaAbstract:The genus Durvillaea includes six currently accepted species, as well as two newly proposed species. Durvillaea spp. have a diplontic life cycle, lack a free-living gametophyte and have oogamous reproduction. All Durvillaea species require rocky substrate for attachment and wave-exposed environments. These “southern bull kelps” occur exclusively in the Southern Hemisphere and are important foundation species, in most cases controlling local community structure, influencing biodiversity, and providing food and habitat for other culturally and economically important species. Most species are non-buoyant and these have restricted geographic ranges, in some cases endemic to small oceanic islands. Buoyant members of the genus are more widespread, with one species ( Durvillaea antarctica ) found throughout the subantarctic, Chile, and New Zealand. This chapter summarizes the taxonomy, biology, and economic importance of Durvillaea species, with a focus on aspects relevant to their availability and productivity as crop plants. Systematics, distribution, ecology, life histories, population status, harvesting times, protection, management and chemical composition are covered. Much of the available data are for the species Durvillaea antarctica , D. willana , and D. potatorum . The techniques used in harvesting and the human uses of Durvillaea spp. (e.g., as food) are described, along with recommendations for harvest timing and methods.
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long term persistence of the floating bull kelp Durvillaea antarctica from the south east pacific potential contribution to local and transoceanic connectivity
Marine Environmental Research, 2019Co-Authors: Fadia Tala, Andrés Mansilla, Marcel Velásquez, Erasmo C. Macaya, Boris A Lopez, Ricardo Jeldres, Jaime OjedaAbstract:Abstract Current knowledge about the performance of floating seaweeds as dispersal vectors comes mostly from mid latitudes (30°–40°), but phylogeographic studies suggest that long-distance dispersal (LDD) is more common at high latitudes (50°–60°). To test this hypothesis, long-term field experiments with floating southern bull kelp Durvillaea antarctica were conducted along a latitudinal gradient (30°S, 37°S and 54°S) in austral winter and summer. Floating time exceeded 200d in winter at the high latitudes but in summer it dropped to 90d, being still higher than at low latitudes (
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morphological and physiological differences between two morphotypes of Durvillaea antarctica phaeophyceae from the sub antarctic ecoregion of magallanes chile
Journal of Applied Phycology, 2017Co-Authors: Fernando J Mendez, Fadia Tala, Jaime Ojeda, R Rautenberger, Sebastian Rosenfeld, Juan Pablo Rodriguez, Johanna Marambio, P Ocaranza, Andrés MansillaAbstract:The coastal marine ecosystems of the sub-Antarctic ecoregion of Magallanes in southern Chile are strongly characterized by environmental heterogeneity with a unique and high biodiversity of benthic macroalgae. The kelp Durvillaea antarctica (Phaeophyceae) is abundant in the intertidal in this region. Two morphotypes, one with elongated-cylindrical (“morphotype EC”) and one with laminar (“morphotype L”) blades, have been collected from a wave-protected site at the Strait of Magellan and the wave-exposed shores of the isolated Otway Sound. Morphometric and physiological (by chlorophyll fluorescence) analyses showed significant differences between the two morphotypes regarding the morphology, the maximum electron transport rates (ETRmax), and the chlorophyll c concentration. These morphological and physiological differences can be linked to their hydrodynamic environment. The presence of two different species in the region of Magallanes based on the measured parameters is discussed. This study may be useful for future genetic and biotechnological investigations and draws attention to D. antarctica as a species of commercial value among the marine resources of Chile.
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daily and seasonal changes of photobiological responses in floating bull kelp Durvillaea antarctica chamisso hariot fucales phaeophyceae
Phycologia, 2017Co-Authors: Fadia Tala, Miguel Angel Pennadiaz, Guillermo Lunajorquera, Eva Rothausler, Martin ThielAbstract:Abstract: Floating seaweeds are important dispersal vehicles, especially for organisms with limited movement capacities and for the seaweeds themselves. The persistence of floating seaweeds is determined by the balance between their acclimation potential and the environmental pressures at the sea surface. Solar radiation is the most important inducer of physiological stress, varying in intensity throughout the day and the year. Therefore photoinhibition and subsequent recovery can change depending on the daily radiation dose and season. The bull kelp Durvillaea antarctica is one of the most common floating seaweeds in the southern oceans, including New Zealand, Chile, and most subantarctic islands. Herein, daily cycles of maximum quantum yield (Fv/Fm), photoinhibition and recovery levels were examined in microcosm experiments with floating D. antarctica throughout the year, focusing on the blade side exposed to solar radiation (sunny vs shadow side). Also, the effect of simulated wave action (blade turnov...
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seasonal variation in floating persistence of detached Durvillaea antarctica chamisso hariot thalli
Botanica Marina, 2013Co-Authors: Angelika Graiff, Fadia Tala, Ulf Karsten, Steffi Meyer, David Pfender, Martin ThielAbstract:Several large kelp species are capable of long- distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may vari- ably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate dis- integration and cause rapid sinking. We used the bull kelp Durvillaea antarctica from northern-central Chile (30 ° S) to test seasonal variation in floating persistence. Experiments with tethered specimens were conducted in all seasons to assess how variable environmental conditions influence the morphology and photosynthetic characteristics of floating D. antarctica . Floating specimens stayed afloat at the surface for more than 1 month during moderate envi- ronmental conditions that prevailed in winter, spring, and fall. However, higher water temperatures and intense solar radiation in summer resulted in significant biomass losses and rapid disintegration of the floating kelps; conse- quently, they sank within < 1 month. These strong seasonal effects were reflected in decreasing maximal quantum yield as well as in maximum relative electron transport rates of photosynthesis. Understanding physiological responses of floating algae is important because increasing global tem- peratures and shifts in solar radiation may strongly affect the survival of floating algae, potentially reducing the dis- tances and frequencies of rafting dispersal.
David R. Schiel - One of the best experts on this subject based on the ideXlab platform.
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Local Extinction of Bull Kelp (Durvillaea spp.) Due to a Marine Heatwave
Frontiers in Marine Science, 2019Co-Authors: Mads S. Thomsen, Paul M. South, Luca Mondardini, Tommaso Alestra, Shawn Gerrity, Leigh W. Tait, Stacie A. Lilley, David R. SchielAbstract:Detailed research has documented gradual changes to biological communities attributed to increases in global average temperatures. However, localized and abrupt temperature anomalies associated with heatwaves may cause more rapid biological changes. We analysed temperature data from the South Island of New Zealand and investigated whether the hot summer of 2017/18 affected species of bull kelp, Durvillaea antarctica, D. poha and D. willana. Durvillaea spp. are large iconic seaweed that inhabit the low intertidal zone of exposed coastlines, where they underpin biodiversity and ecosystem functioning. Sea surface temperatures during the summer of 2017/18 included the strongest marine heatwaves recorded in 38 years of existing oceanic satellite data for this region. Air temperatures were also high, and, coupled with small wave heights, resulted in strong desiccation stress during daytime low tides. Before-After analysis of drone images of four reef platforms (42, 42, 44 and 45 ˚S) was used to evaluate changes to bull kelp over the hot summer. Bull kelp loss varied among species and reefs, with the greatest (100%) loss of D. poha at Pile Bay in Lyttelton Harbour (44 ˚S). In Pile Bay, sea surface temperature exceeded 23 ˚C and air temperatures exceeded 30 ˚C, while Durvillaea was exposed for up to 3 hours per day during low tide. Follow-up surveys showed that all bull kelps were eliminated from Pile Bay, and from all reefs within and immediately outside of Lyttelton Harbour. Following the localized extinction of bull kelp in Pile Bay, the invasive kelp Undaria pinnatifida recruited in high densities (average of 120 m-2). We conclude that bull kelps are likely to experience additional mortalities in the future because heatwaves are predicted to increase in magnitude and durations. Losses of the endemic D. poha are particularly concerning due to its narrow distributional range.
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Local Extinction of Bull Kelp (Durvillaea spp.) Due to a Marine Heatwave
Frontiers Media S.A., 2019Co-Authors: Mads S. Thomsen, Paul M. South, Luca Mondardini, Tommaso Alestra, Shawn Gerrity, Stacie A. Lilley, Leigh Tait, David R. SchielAbstract:Detailed research has documented gradual changes to biological communities attributed to increases in global average temperatures. However, localized and abrupt temperature anomalies associated with heatwaves may cause more rapid biological changes. We analyzed temperature data from the South Island of New Zealand and investigated whether the hot summer of 2017/18 affected species of bull kelp, Durvillaeaantarctica, D. poha, and D. willana.Durvillaea spp. are large iconic seaweeds that inhabit the low intertidal zone of exposed coastlines, where they underpin biodiversity and ecosystem functioning. Sea surface temperatures (SST) during the summer of 2017/18 included the strongest marine heatwaves recorded in 38 years of existing oceanic satellite data for this region. Air temperatures were also high, and, coupled with small wave heights, resulted in strong desiccation stress during daytime low tides. Before-After analysis of drone images of four reef platforms (42, 42, 44, and 45°S) was used to evaluate changes to bull kelp over the hot summer. Bull kelp loss varied among species and reefs, with the greatest (100%) loss of D.poha at Pile Bay in Lyttelton Harbor (44°S). In Pile Bay, SST exceeded 23°C and air temperatures exceeded 30°C, while Durvillaea was exposed for up to 3 h per day during low tide. Follow-up surveys showed that all bull kelps were eliminated from Pile Bay, and from all reefs within and immediately outside of Lyttelton Harbor. Following the localized extinction of bull kelp in Pile Bay, the invasive kelp Undaria pinnatifida recruited in high densities (average of 120 m-2). We conclude that bull kelps are likely to experience additional mortalities in the future because heatwaves are predicted to increase in magnitude and durations. Losses of the endemic D. poha are particularly concerning due to its narrow distributional range
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Table_1_Local Extinction of Bull Kelp (Durvillaea spp.) Due to a Marine Heatwave.DOCX
2019Co-Authors: Mads S. Thomsen, Paul M. South, Luca Mondardini, Tommaso Alestra, Shawn Gerrity, Stacie A. Lilley, Leigh Tait, David R. SchielAbstract:Detailed research has documented gradual changes to biological communities attributed to increases in global average temperatures. However, localized and abrupt temperature anomalies associated with heatwaves may cause more rapid biological changes. We analyzed temperature data from the South Island of New Zealand and investigated whether the hot summer of 2017/18 affected species of bull kelp, Durvillaeaantarctica, D. poha, and D. willana.Durvillaea spp. are large iconic seaweeds that inhabit the low intertidal zone of exposed coastlines, where they underpin biodiversity and ecosystem functioning. Sea surface temperatures (SST) during the summer of 2017/18 included the strongest marine heatwaves recorded in 38 years of existing oceanic satellite data for this region. Air temperatures were also high, and, coupled with small wave heights, resulted in strong desiccation stress during daytime low tides. Before-After analysis of drone images of four reef platforms (42, 42, 44, and 45°S) was used to evaluate changes to bull kelp over the hot summer. Bull kelp loss varied among species and reefs, with the greatest (100%) loss of D.poha at Pile Bay in Lyttelton Harbor (44°S). In Pile Bay, SST exceeded 23°C and air temperatures exceeded 30°C, while Durvillaea was exposed for up to 3 h per day during low tide. Follow-up surveys showed that all bull kelps were eliminated from Pile Bay, and from all reefs within and immediately outside of Lyttelton Harbor. Following the localized extinction of bull kelp in Pile Bay, the invasive kelp Undaria pinnatifida recruited in high densities (average of 120 m-2). We conclude that bull kelps are likely to experience additional mortalities in the future because heatwaves are predicted to increase in magnitude and durations. Losses of the endemic D. poha are particularly concerning due to its narrow distributional range.
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© 1990 Kluwer Academic Publishers. Printed in Belgium. The harvesting of macroalgae in New Zealand
2015Co-Authors: David R. Schiel, Wendy A. NelsonAbstract:Several species of algae have been commercially harvested in New Zealand, mainly for extraction of agar and alginates. In the past, the harvest was comprised mostly of shore-cast plants. There has been more recent interest, however, in harvesting attached plants of Pterocladia spp., Porphyra spp., Gracilaria sordida, Durvillaea spp., Macrocystis pyrifera, and Ecklonia radiata. The ecological effects of harvesting attached algae depend largely on the sizes of plants, the season of removal, the patch size of clearances, and the proximity and identity of mature plants. These have not been well-studied for seaweeds in New Zealand, but population and life history studies indicate that harvesting methods affect the continuity of algal resources, at least on a local scale, and are crucial factors in their management
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self replacement and community modification by the southern bull kelp Durvillaea antarctica
Marine Ecology Progress Series, 2005Co-Authors: David I Taylor, David R. SchielAbstract:Stands of the southern bull kelp Durvillaea antarctica (Chamisso) Hariot provide consid- erable biomass and a major habitat in the lower intertidal zone of exposed shores on the austral land masses. Whiplash effects of adult fronds (up to 10 m long) can affect recruitment, growth and survival of understorey species and potentially large brown algal competitors, thereby affecting community development. In southern New Zealand, D. antarctica is one of several species of large brown algae inhabiting the low intertidal zone. Effects of its canopy and its associated understorey coralline algae on community development were tested at 2 sites (Moeraki and Kaikoura) at different times of year between February 1999 and October 2001. Removal of D. antarctica canopies had surprising results compared to most studies where canopies of large brown algae were removed. The greatest initial recruitment of bull kelp occurred beneath intact canopies, usually in areas where corallines were removed. Recruitment was highly variable through time, with peaks occurring in June and October (austral winter-spring), depending mostly on when canopies were removed. There was an order of magnitude difference in recruitment between sites. The cover of turfing coralline algae, however, increased in all canopy removal treatments. A major source of mortality of young recruits was graz- ing by the herbivorous fish Odax pullus. Its distinct grazing marks were seen on recruits, almost exclusively outside the canopy of bull kelp where 80% of recruits were grazed. We show that D. antarctica has the ability to recruit beneath adult canopies, but that survival and growth ultimately depend on the extent of canopies, underlaying benthic algae and escapes from grazing by herbivo- rous fish.
