Ylva S Olsen

Ylva S Olsen
University of Western Australia | UWA · Oceans Institute

PhD Biology, Boston University

About

44
Publications
66,470
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5,678
Citations
Additional affiliations
January 2013 - present
September 2010 - September 2012
Mediterranean Institute for Advanced Studies (IMEDEA)
Position
  • Research: IMEDEA/CSIC
January 2009 - May 2010
Bangor University

Publications

Publications (44)
Preprint
Coral reefs face increasing pressures in response to unprecedented rates of environmental change at present. The coral reef physical framework is formed through the production of calcium carbonate (CaCO3) and maintained by marine organisms, primarily hermatypic corals, crustose coralline algae (CCA), and other calcifying algae. The Kimberley bioreg...
Article
Full-text available
Fish biodiversity can be measured by capturing and then sequencing free DNA present in water. Such environmental DNA (eDNA) methods offer an effective, noninvasive tool for species diversity measurement, although standardized protocols are not yet developed. We investigate how metrics of fish biodiversity revealed through eDNA analysis of water are...
Article
Full-text available
A central question in contemporary ecology is how climate change will alter ecosystem structure and function across scales of space and time. Climate change has been shown to alter ecological patterns from individuals to ecosystems, often with negative implications for ecosystem functions and services. Furthermore, as climate change fuels more freq...
Article
Full-text available
Most of the world’s tropical coastal and shelf areas are heavily affected by anthropogenic activities, but the north-west shelf of Australia is considered a ‘very low-impact’ area. The role of herbivory on coral reefs is recognised, but most of that research comes from reefs with considerable land-based impacts. In this study we sampled the teleost...
Article
Aim Marine macrophytes are important components of tropical reefs that are influenced by environmental conditions and biotic interactions. Here, we aimed to identify the factors that shape macrophyte communities on shallow reefs in a region with limited anthropogenic impacts, but that is influenced by periodic disturbances from cyclones and marine...
Thesis
Full-text available
Connectivity of populations through the transfer of individuals is one of the key processes for maintaining ecosystem stability and resilience of coastal ecosystems. During reproduction, dislodged seaweeds of the genus Sargassum form large pelagic surface rafts that can persist for several weeks, and potentially act as a dispersal vector. In surfac...
Article
Full-text available
Connectivity of populations through the transfer of individuals is one of the key processes for maintaining ecosystem stability and resilience of coastal ecosystems. During reproduction, dislodged seaweeds of the genus Sargassum form large pelagic surface rafts that can persist for several weeks, and potentially act as a dispersal vector. In surfac...
Article
Seagrasses thrive in anoxic sediments where sulphide can accumulate to phytotoxic levels. So how do seagrasses persist in this environment? Here, we propose that radial oxygen loss (ROL) from actively growing root tips protects seagrasses from sulphide intrusion not only by abiotically oxidising sulphides in the rhizosphere of young roots, but also...
Chapter
As concentrations of atmospheric CO2 increase, mean temperatures across the globe rise, the carbon system equilibrium in the ocean shifts, and pH is reduced in a process termed Ocean Acidification (OA). These changes can dramatically alter seagrass meadows as both temperature and pH fundamentally influence biochemistry and physiology of plants. Sea...
Article
The presence of oxygen in seagrass tissues, which plays a role in preventing seagrass die-off, is partly regulated by environmental conditions. Here, we examined the relationship between oxygen (O2) in the rhizomes of Posidonia sinuosa and key environmental variables at Garden Island, Western Australia. We made in situ measurements of internal oxyg...
Article
Full-text available
Phenolic compounds are found in all brown macroalgae and function as cell wall structure, UV protection and as herbivore deterrents. The concentrations of phenolic compounds vary among taxa and between temperate and tropical ecosystems. Australasia has high concentrations of soluble phenolics compared to other regions. Presently, relationships betw...
Article
We evaluated the photosynthetic performance of Posidonia oceanica during short-term laboratory exposures to ambient and elevated temperatures (24–25 °C and 29–30 °C) warming and pCO2 (380, 750 and 1000 ppm pCO2) under normal and low light conditions (200 and 40 μmol photons m⁻² s⁻¹ respectively). Plant growth was measured at the low light regime an...
Article
Full-text available
Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically dema...
Article
Full-text available
Canopy-forming seaweeds, as primary producers and foundation species, provide key ecological services. Their responses to multiple stressors associated with climate change could therefore have important knock-on effects on the functioning of coastal ecosystems. We examined interactive effects of UVB radiation and warming on juveniles of three habit...
Data
Health status of Ecklonia, Scytothalia and Sargassum incubated at temperatures from 16 to 30°C, with (black) or without (white) UVB radiation (triangles: after 1 week; circles: after 2 weeks). (DOCX)
Article
Global warming is predicted to alter host-pathogen relationships and increase disease outbreaks in terrestrial and marine environments. We evaluated the effect of warming on the susceptibility of Cymodocea nodosa to infection by Labyrinthula sp. (the causative agent of seagrass wasting disease) by monitoring disease symptoms and seagrass photobiolo...
Article
Full-text available
Climate change is predicted to alter pathogen–host relationships and there is evidence of an increase in disease in both terrestrial and marine environments. Infection rates do not always increase linearly with temperature since thermal tolerance ranges of host and pathogens do not necessarily overlap and the host may benefit from thermal refugia o...
Article
Full-text available
Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5–12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturati...
Data
Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5-12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturati...
Data
We examined the long-term effect of naturally acidified water on a Cymodocea nodosa meadow growing at a shallow volcanic CO2 vent in Vulcano Island (Italy). Seagrass and adjacent unvegetated habitats growing at a low pH station (pH = 7.65 ± 0.02) were compared with corresponding habitats at a control station (pH = 8.01 ± 0.01). Density and biomass...
Article
Full-text available
Macrophytes growing in shallow coastal zones characterized by intense metabolic ac- tivity have the capacity to modify pH within their canopy and beyond.We observed diel pH ranges is in shallow (5–12m) seagrass (Posidonia oceanica) meadows from 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation...
Article
Full-text available
Ocean acidification due to anthropogenic CO2 emissions is a dominant driver of long-term changes in pH in the open ocean, raising concern for the future of calcifying organisms, many of which are present in coastal habitats. However, changes in pH in coastal ecosystems result from a multitude of drivers, including impacts from watershed processes,...
Article
Anthropogenically induced changes to estuaries, including shifts from seagrass to macroalgae-dominated habitats, have led to concerns about the ability of estuaries to support fish and invertebrates. To assess differences in habitat quality of seagrass and macroalgae, we examined faunal community structure and consumer carbon assimilation in adjace...
Article
Full-text available
We experimentally examined the effects of increased temperature on growth and demography of two Mediterranean seagrasses Posidonia oceanica and Cymodocea nodosa. Shoots of C. nodosa and seedlings and shoots of P. oceanica were kept in mesocosms for 3 months and exposed to temperatures between 25 and 32 °C encompassing the range of maximum summer se...
Article
We examined the impact of long-term cattle grazing on soil processes and microbial activity in a temperate salt marsh. Soil conditions, microbial biomass and respiration, mineralization and denitrification rates were measured in upper salt marsh that had been ungrazed or cattle grazed for several decades. Increased microbial biomass and soil respir...
Article
Full-text available
Eutrophication forces shifts in estuarine producer assemblages from seagrass meadows to communities dominated by macroalgae. This restructuring of the benthic producer assemblage presents challenges and alters food resources available to consumers. We examined food web relationships in 3 sub-estuaries of the Waquoit Bay system, Massachusetts, USA,...
Article
Full-text available
We examined the effect of nutrients and grazers on Thalassia testudinum in Jobos Bay, Puerto Rico by fertilizing sediment and manipulating grazer abundances. Bottom-up effects were variable: Added nutrients did not increase seagrass aboveground biomass, but decreased belowground biomass—perhaps as a result of less biomass being allocated to belowgr...
Chapter
Full-text available
Macrophytes provide important estuarine benthic habitats and support a significant portion of estuarine productivity. The composition and characteristics of these benthic communities are regulated bottom-up by resource availability and from the top-down by herbivory and predation. Human activities in coastal zones have dramatically altered the rela...
Article
Full-text available
Receiving coastal waters and estuaries are among the most nutrient-enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast-growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosph...
Article
Couplings between land use and marine food webs in tropical systems are poorly understood. We compared land-sea coupling in seven sites around Puerto Rico, differing in the degree of precipitation and urbanization, by measuring delta(13)C and delta(15)N in producers and consumers. delta(15)N values were influenced by human activity: the food web fr...
Article
Full-text available
Anthropogenic nutrient loading to coastal waters has increased producer biomass, leading to more frequent hypoxic events particularly in estuarine systems. To examine how eutrophication and hypoxia might alter consumer assemblages, we surveyed benthic communities in 2 sub-estuaries of Waquoit Bay, Massachusetts, representing a eutrophic-hypoxic reg...
Article
Full-text available
Increased nutrient inputs to temperate coastal waters have led to increased occurrences of macroalgal blooms worldwide, To identify nutrients that are limiting to rnacroalgae and to determine whether different forms of these nutrients and long-term ambient nutrient conditions affect macroalgal response, we used in situ enrichment methods and tested...
Article
In September 1969, the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor, MA. Today a substantial amount, approximately 100 kg, of moderately degraded petroleum remains within the sediment and along eroding creek banks. The ribbed mussels, Geukensia demissa, which inhabit the salt marsh creek bank, are e...
Article
Full-text available
Millions of metric tons of plastic are produced annually. Countless large items of plastic debris are accumulating in marine habitats worldwide and may persist for centuries ([ 1 ][1]–[ 4 ][2]). Here we show that microscopic plastic fragments and fibers ([Fig. 1A][3]) are also widespread in the
Article
A biokinetic model is presented that simulates the uptake and release of (99)Tc by the European lobster (Homarus gammarus). This organism is of significant radioecological interest since lobsters, in contrast to most other organisms, have a high affinity for (99)Tc. The model is designed to represent annually averaged (99)Tc concentrations in lobst...
Article
Chemical and enzymatic reagents have been employed to determine available concentrations of Fe, Mn, Cu and Zn in contaminated estuarine sediment. Gastric and intestinal enzymes (pepsin, pH 2, and trypsin, pH 7·6, respectively) removed significantly more metal than was water-soluble or exchangeable (by seawater or ammonium acetate), while gastro-int...

Projects

Projects (3)
Project
The Mediterranean Sea is warming two to three times faster than the global ocean. The temperature increase is already impacting the marine biodiversity in the Mediterranean, particularly benthic sessile organisms. Global and regional circulation models, under IPCC scenarios of greenhouse gas emissions, project a rapid warming and an increase in intensity and frequency of extreme thermal values in the Mediterranean for the 21st Century, threatening actochthonous biodiversity. Because the Mediterranean is a semi-enclosed sea, endemic marine species have limited scope to adapt to warming by moving their biogeographic limits towards the poles following the migration of isotherms and they should thermally adapt to decrease their extinction risk or they could be represented by relict populations in few colder Mediterranean spots. Similarly, Mediterranean warming could trigger changes in abundance and distribution of other Mediterranean species with wider biogeographic ranges. The Mediterranean is the European sea with the largest number and entry rates of exotic species, some of them with invasive traits, due to the opening of the Suez Canal, high maritime traffic and aquaculture activity. There is evidence that Mediterranean warming is facilitating the proliferation of exotics in this sea. Habitat forming macrophytes are the main primary producers in the coastal Mediterranean, they provide refuge and habitat to a large number of species and, in sandy coastal areas, they are important carbon sinks and prevent coastal erosion. Mediterranean warming could trigger the substitution and loss of abundance of endemic, or narrow thermal niches, macrophyte, and associated fauna, species by those of warmer thermal ranges as well as shifts in the ecosystem services macrophyte dominated ecosystems provide. The aim of MedShift project is to evaluate the vulnerability and adaptation capacity of Mediterranean endemic and autochtonous marine vegetation and associated species to global warming, the role of warming to facilitate the proliferation of invasive macrophytes with tropical and subtropical origin and the effect of the shift in habitat forming macrophytes on the ecosystem services macrophyte ecosystems provide. We will achieve these objectives by combining experiments, field observations, monitoring of long term ecosystem changes by continuing time series initiated during previous projects and meta-analysis.
Project
Quantify the changes in chemical composition and physiology of Sargassum plants as they form floating rafts. This includes quantification of photosynthetic parameters, phenolic compounds, and pigments.
Project
Much in the same way that we rely on our gut flora to help digest our food, seagrasses also rely on microbes living in, on or near their roots (the rhizosphere) to regenerate their nutrients. However, the interaction among seagrass roots, the sediments and the microbes they contain remains, quite literally, in the dark. Gaining a greater understanding of these interactions is imperative if we are to better manage these ecosystems, particularly as seagrass habitat continues to disappear across the globe. My research therefore aims to shed some light on the seagrass rhizosphere by characterizing root released organic matter and oxygen, and determining its role in microbial nutrient cycling