92. Ocean Acidification and Increased Temperature have both Positive and Negative Effects on Early Ontogeny Traits of a Rocky Shore Keystone Predator Species

Manriquez PH (1)*, Torres R (2), Jara ME (1), Seguel ME (1), Alarcon E (2), Lee MR (3)

1 Laboratorio de Ecología y Conducta de la Ontogenia Temprana (LECOT), Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Avenida Ossandón 877, Coquimbo, Chile
2 Centro de Investigación en Ecosistemas de la Patagonia (CIEP), Coyhaique, Chile
3 Centro i~mar, Universidad de Los Lagos, Camino a Chinquihue km. 6, Puerto Montt, Chile.

Background
Juveniles of marine invertebrates with complex life histories are the most vulnerable stage in the benthic phase. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal of southern Chile (39°S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits.

Methods
The individuals were exposed long-term (5.8 months) to contrasting pCO2 (500 and 1400 μatm) and temperature (15, 19 °C) levels. After this period we compared body growth traits, dislodgement resistance, self-righting and metabolic rates.

Findings
None of these traits were significantly affected by the interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15 °C. High pCO2 levels also had a negative effect on the predator-escape response. However, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour.

Conclusions
We conclude that the implications of climate change projections for C. concholepas in the Chile-Peru Humboldt current system might be less severe than expected.

93. Seagrass fitness under ocean warming and acidification

Tiago Repolho (1)*, Gisela Dionísio (1, 2), Ana R. Lopes (1), Tiago F. Grilo (1), José R. Paula (1), Ricardo Calado (2), Bernardo Duarte (3), Isabel Caçador (3), Rui Rosa (1)

1 MARE – Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
2 Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
3 MARE – Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Campo Grande, Portugal

Background
Within marine coastal environments, seagrasses are experiencing a global decline at unprecedented levels never perceived before. Their response to combined climate change stressors is still elusive or even slightly understood and therefore, it is not known if they will be able to cope in a future changing ocean.
The aim of our study is to unravel, the combined effects of ocean warming and acidification on survival and several photobiological processes of dwarf seagrass (Zostera noltii Hornem). Moreover, it is worth noting that Z. noltii meadows are among the most biodiverse temperate marine ecosystems and hold significant ecological importance in many marine coastal habitats.

Methods
Zostera noltii was acclimated at rising pCO2 (ΔpH=0.4, pH 7.6/8.0) and ocean warming (+4°C). Seagrass survival was determined. Pulse amplitude modulation (PAM) fluorometry was used to monitor photosynthetic activity. Photosynthetic pigment quantification was performed spectrophotometrically.

Findings
Zostera noltii shoot density was significantly reduced under warming conditions. Photosynthetic electron transport rate (ETR) and maximum photosynthetic quantum yield (Fv/Fm) levels were significantly higher under control conditions and lower under warming/hypercapnic scenario. Chl_a, Chl_b and Chl_a/Chl_b ratio were significantly higher (control) and lower under the warming/hypercapnic scenario. Pheophytin a, Pheophytin b, Auroxanthin, Antheraxanthin, β-carotene, Lutein and total carotenoid concentrations showed significantly higher concentrations under the warming/normocapnic scenario. Positive correlations between quantified photosynthetic pigments and leaf coloration were found. De-Epoxidation State (DES) showed significantly lower values under control conditions. A negative correlation between DES and Chl_a, Total-Chl and Total carotenoids was also found.

Conclusions
Zostera noltii survival will be severely affected under a future warming scenario. Ocean acidification seems to be beneficial and improved seagrass resilience within a warming ocean scenario. Moreover, light harvesting and photo-protection mechanisms will be adversely affected by future warming scenario but not acidification.

89. Climate Change-Driven Multistressor Impacts on a Shelf Ecosystem: The Gulf of Maine

Cynthia H. Pilskaln (1), Zhaohui A. Wang (2), David W. Townsend (3), Gareth Lawson (4), Joseph Salisbury (5)

1 School for Marine Science and Technology, University of Massachusetts Dartmouth, New Bedford, MA 02744, USA
2 Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
3 School of Marine Sciences, University of Maine, Orono, ME 04469, USA
4 Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
5 Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA

Background
The Gulf of Maine on the Northwest Atlantic margin is experiencing substantial decadal changes in water column biogeochemical characteristics and planktonic-benthic ecosystem structure and function. Such transformations are believed to be the result of global anthropogenic forcing with acute effects on the North Atlantic region.

Methods
In order to examine linkages between drivers, stressors and specific impacts on the biogeochemical system and ecology, multiple chemical and biological data sets collected by numerous Gulf of Maine researchers from time-series moorings, research cruises and satellite surveys over the course of three decades, are integrated and summarized.

Findings and Conclusions
Recent freshening and warming of the North Atlantic/Gulf of Maine appear to be significant drivers of plankton and fish community regimes shifts, changes in carbon delivery rates, variations in benthic community life cycles and production, as well as driving potential impacts on CaCO3 precipitation/dissolution rates and near-bottom dissolved oxygen levels. Implications are that these trends will continue along their present trajectory into the future as a function of increasing atmospheric carbon dioxide levels and global temperature rise.

91. Combined effects of ocean acidification and metals on sea urchin and oyster larval development

N.Dorey*, E. Maboloc, K. Chan

Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong

We live in a multi-stressor world where oceans are impacted by both global (e.g. CO2-driven climate change and ocean acidification) and local pressures. Coastal marine organisms are already challenged by anthropogenic stressors such as pollutants, that may magnify the impacts of future global changes. For instance, ocean acidification is likely to change metal speciation as well as bioaccumulation and, consequently, metal toxicity. There is few information available on the effects of these interactions on marine biota. In this study, we provide insight on the combined effects of ocean acidification and copper on the larval development of the sea urchin Heliocidaris crassispina and the oyster Crassostrea hongkongensis. In laboratory culture, sea urchin larvae appeared quite robust to predicted pH changes as well as to high levels of copper contamination, albeit some morphometric changes. The association of both stressors significantly increased larval mortality, anomalies and respiration. We still lack an understanding of how biological mechanisms respond to co-occurring factors such as metal contamination and ocean acidification, making accurate projections regarding the future of ecologically- and economically- important marine ecosystems difficult.

90. Combined effect of elevated pCO2 and temperature on an estuarine planktonic community and dimethylsulfide production: a mesocosm study

Bénard, Robin (1)*, Levasseur, Maurice (1), Ferreyra, Gustavo (2), Mucci, Alfonso (3), Scarratt, Michael G. (4), Starr, Michel (4), Blais, Marie-Amélie (1), Tremblay, Jean-Éric (1)

1 Université Laval, Québec, Québec, G1V 0A6, Canada
2 Université du Québec à Rimouski, Rimouski, Québec, G5L 3A1, Canada
3 McGill University, Montréal, Québec, H3A 0G4, Canada
4 Maurice-Lamontagne Institute, Mont-Joli, Québec, G5H 3Z4

Anthropogenic carbon dioxide (CO2) emissions will result in concomitant warming and acidification of oceanic waters. There is still limited information on how changes in these two drivers will affect ocean ecosystems. To start filling this knowledge gap, we conducted a mesocosm experiment where we exposed a natural plankton community of the St. Lawrence Estuary to two temperatures (in situ and +5°C) and to a range of decreasing pH conditions (from -0.2 to -0.6 unit). The pH was manipulated by addition of CO2-bubbled artificial seawater to ~3m3 mesocosms and was kept constant for 14 days. A phytoplankton bloom dominated by the diatom Skeletonema costatum developed in all twelve enclosures resulting in a complete nutrients drawdown. Phytoplankton growth was higher at the highest temperature but was not affected by the decreasing pH. Dimethylsufide (DMS) concentrations remained relatively low during the development of the bloom but increased significantly during the declining phase. DMS net production was enhanced by 250% due to the increasing temperature and slightly negatively impacted by acidification. These results suggest that the potential negative impact of ocean acidification on DMS ocean production may be cancelled by the stronger positive effect of warming on the recycling of the most important source of sulfur of the atmosphere.

102. The survival of pteropod larvae (Limacina helicina antarctica) in a changing world

Jessie Gardner (1,2)*, Dorothee Bakker (2), Geraint Tarling (1), Victoria Peck (1) and Clara Manno (1)

1 British Antarctic Survey, Cambridge, Cambridgeshire, CB3 0ET, United Kingdom
2 University of East Anglia, Norwich, Norfolk, NR4 7TJ, United Kingdom

Background
Numerous studies have demonstrated that early life stages of marine calcifiers are particularly susceptible to ocean acidification and warming. Thecosome pteropods have been identified as particularly vulnerable to the projected oceanic changes because of their aragonite shells. Pteropods can dominate zooplankton communities, are key components of high latitude pelagic food webs and act as important contributors to carbon and carbonate fluxes. However, difficulty in capture, incubation and cultivation has left our present understanding of their life history incomplete, especially with regard to the relative vulnerabilities of early life stages. This is particularly crucial within the Southern Ocean due to rapid warming and acidification.

Methods
We investigated the response of Limacina helicina antarctica to the predicted synergistic changes in temperature and pH within the Southern Ocean. Adults were incubated on-board the R.R.S. James Clark Ross for 18 days under ambient conditions (1.5˚C and pH 8.1), during which time some specimens spawned eggs. Larvae that subsequently hatched were incubated under ambient and projected 2100 temperature (1.5 or 3.5˚C) and pH (7.6 or 8.1) regimes. Incubators comprised of filtered seawater with no antibiotic, sterilization, nutrition or stirring techniques. After five days, larval survival was investigated along with shell morphology and dissolution via scanning electron microscopy.

Findings
We demonstrated ocean acidification significantly reduced pteropod survival and caused shell dissolution. Warming alone had little impact on pteropods but in synergism with acidification individuals displayed shell deformation and dissolution.

Conclusions
This is the first evidence that ocean acidification and warming impacts Limacina helicina antarctica larvae in the Southern Ocean. We demonstrate that acidification and warming produce a synergistic, negative impact on pteropods. Our findings address a key knowledge gap in temperature and ocean acidification impact on the early life-stages of this sentinal species.

101. Methylmercury and climate change: effects on behaviour of Solea senegalensis

Eduardo Sampaio (1), Ana Luísa Maulvaut (1,2,3), Vanessa Lopes (3), Pedro Pousão (1), António Marques (1,2), Rui Rosa (3)*

1 Divisão de Aquacultura e Valorização (DivAV), Instituto Português do Mar e da Atmosfera (IPMA, I.P.), Av. Brasília, Lisboa 1449-006, Portugal
2 Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Rua das Bragas, 289, 4050-123 Porto, Portugal
3
MARE- Marine Environmental Science Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo 939, Cascais 2750-374, Portugal

Background
Methylmercury (MeHg) is an extremely hazardous pollutant, highly accumulating in brain and central nervous system cells. In order to accurately anticipate future neurotoxic effects in fish, warming and acidification must be taken into account. Lateralization produces faster and more efficient responses to external stimuli, e.g. predator avoidance or prey capture. Flatfish use the bottom as camouflage, to avoid being detected by predators and preys. Consequently, disruption in bottom-choosing ability and lateralization may prove disastrous at an ecological level. Thus, we assessed effects on behaviour processes stemmed from MeHg contamination, subjected to warming and acidification stressors, in S. senegalensis.

Methods
During 28 days, S. senegalensis specimens were maintained under three factor crossed treatments: MeHg contaminated feed (uncontaminated: 0.60 µg g-1, contaminated: 8.01 µg g-1), pH (ambient CO2: 8.0, high CO2: 7.6), and temperature (ambient: 19ºC, high: 23ºC). Behaviour was assessed by calculating absolute (individual level) and relative (population level) lateralization using a detour test, as well as by habitat preference, measuring time spent (maximum 180 minutes) between two habitats: simple and complex (all tests, n=10 fish/treatment).

Findings
MeHg intake correlated with increased time spent in complex habitat, where fish could not camouflage or hide efficiently. In addition, intake of MeHg reduced absolute lateralization on each fish, consequently leading to complete loss of lateralization at populational level. Acidification also led to increased time spent in complex habitat, but only in uncontaminated treatments. Finally, temperature and acidification may interact with MeHg in reducing absolute lateralization.

Conclusions
MeHg intake reported major negative effects on both behavioural parameters tested. Climate change may also play a minor role in modulating individual fish lateralization. Regarding habitat preference, acidification effects are downplayed in the presence of MeHg. Disruption of these important behavioural processes may lead to a significant decrease in the ecological fitness of S. senegalensis.

100. Bacterial response to ocean acidification and warming varies with plankton community composition

Tim J. Burrell (1,2), Elizabeth W. Maas (1), Debbie A. Hulston (1), Cliff S. Law (1,3)*

1 National Institute of Water and Atmospheric Research, Greta Point, Kilbirnie, Wellington 6002, New Zealand
2 Victoria University of Wellington, School of Biological Sciences, Wellington 6140, New Zealand
3 Department of Chemistry, University of Otago, Dunedin, 9016, New Zealand

Background
Bacterial extracellular enzymes play an important role in the degradation of organic matter in the surface ocean, but are sensitive to changes in pH and temperature. To date there has been limited consideration of the interaction of these two stressors, and also how this response may be influenced by phytoplankton community composition.

Methods
This study tested the individual and combined effects of ocean acidification (-0.3) and warming (+3°C) projected for the year 2100 on bacterial abundance, process rates and diversity in 5-6 day incubations using four different plankton communities from surface waters east of New Zealand.

Findings
Although the magnitude and temporal response varied between phytoplankton communities, bacterial abundance and production generally increased in response to elevated temperature, whereas β-glucosidase (BG) activity showed a stronger response to low pH in some communities, and elevated temperature in others. Cell-specific and bulk leucine aminopeptidase (LAP) activity were consistently higher under low pH, and low pH and elevated temperature combined, in all phytoplankton communities. However the interactive effects of temperature and pH were variable, with an additive response in BG activity and bacterial production observed in only one community, and a synergistic response in LAP activity in two phytoplankton communities.

Conclusions
The results suggest that the effect of lower pH and higher temperature on bacterial processes may partially counteract each other in the future ocean. Warming may stimulate bacterial production, and the increase in LAP activity suggests that ocean acidification may result in differential rates of carbohydrate and amino acid remineralisation in surface waters of the South West Pacific.

99. Multiple climate stressors produce complex trade-offs between metabolic costs and growth in subtidal tropical and temperate gastropods

Charlee A. Corra (1)*, Brian Helmuth (1), Sean D. Connell (3), and Bayden D. Russell (2)

1 Northeastern University, Boston, Massachusetts, 02155, USA
2 The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, China
3 The University of Adelaide, Adelaide, South Australia

Background
The impacts to coastal marine ecosystems resulting from global climate change are increasingly obvious. Many gaps, however, remain in our knowledge of the role ocean acidification, in combination with warming, plays in organismal performance and survival. For example, how ocean acidification will interact with warming to alter the biological performance of benthic grazing species, and whether they will maintain their ecological function under these combined stressors, is poorly understood.

Methods
We exposed two tropical (Trochus sacellum and Turbo argyrostomus) and two temperate (Austrocochlea odontis and Turbo undulatus) species of subtidal gastropod to combinations of ambient and future temperature (ambient summer vs. +3°C) and CO2 (400 ppm vs. 1000 ppm) conditions. A variety of response parameters including Thermal Performance Curves (TPCs), ingestion rates, and growth rates were quantified after six weeks to elucidate the effects of different treatments on physiological performance and energetic partitioning.

Findings
After treatment exposure, responses to warmer temperatures and elevated CO2 varied significantly among treatments and species. Species demonstrated differential ability to acclimate and maintain metabolic function closer to that of individuals under contemporary temperature and CO2 levels. Importantly, the species that were able to alter metabolic function and satisfy higher metabolic demands under future conditions exhibited pronounced growth. This indicates that some species may acclimate to future conditions, however, in the absence of sufficient resources their high energetic demands may compromise their overall fitness.

Conclusions
Given these results, the divergence of metabolic and growth responses among species after exposure to increased temperature and CO2 indicate a diverse array of trade offs to these multiple climate stressors. Compromised fitness may result in reduced abundance of some grazer species under future conditions, which may lead to a breakdown in their ecological function and subsequent knock-on effects/impacts on local ecosystems due to decreased grazing pressure.

98. Long Term Adaption by New Zealand Phytoplankton to Climate Change

Evelyn Armstrong (1)* and Cliff S. Law (2,3)

1 NIWA/University of Otago Research Centre for Oceanography, Department of Chemistry, University of Otago, Dunedin, 9016, New Zealand
2 National Institute of Water and Atmospheric Research, Greta Point, Kilbirnie, Wellington 6002, New Zealand
3 Department of Chemistry, University of Otago, Dunedin, 9016, New Zealand

Background
Climate change and ocean acidification will have major impacts on marine ecosystems and biogeochemical cycles. This will be partly dependent on the response of phytoplankton to future change as they occupy a key role in the cycling of nutrients and carbon. Current research has identified significant changes in growth rate, metabolic processes and nutrient cycling in phytoplankton that may arise in response to increasing temperature and CO2. However, the majority of studies to date have been relatively short-term and so do not consider the potential of phytoplankton to adapt to changing temperature and CO2.

Methods
We are investigating the effect of long term changes in temperature and pH on two New Zealand phytoplankton, a Pseudonitzschia sp. and an E. huxleyi strain, isolated from subantarctic water, by incubating cultures in conditions representing current and future conditions projected for the end of this century (0.3 – 0.4 decrease in pH, 3 oC increase in temperature). The pH of the future culture medium is set using 10% CO2 prior to cells being added, and maintained in all cultures by continuous supply to the headspace of air mixtures with CO2 levels at 380 ppm for current conditions or 750 ppm for future conditions. Cells from the first cultures were harvested to provide baseline values and cell parameters, with follow-up analysis after 4 – 5 months incubation (110 – 120 generations). In addition, cells were cross – inoculated from current to future conditions, and vice versa, to examine adaptation potential.

Findings
Preliminary results indicate changes in diatom growth rate and size whereas cellular chlorophyll remained constant in both treatments, with cellular phosphate increasing under future conditions. Current and future results will be assessed in terms of the implications for future biogeochemical cycles and phytoplankton composition.

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