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.

94. Effects of ocean warming and acidification on the growth of juveniles of two Antarctic Heart Urchins, Abatus ingens and A. shackletoni

Melanie A. Ho (1), Jessica A. Ericson (2,4), Ashley Miskelly (1), Catherine K. King (3), Patti Virtue (2,4), Maria Byrne (1,5)

1 School of Medical Sciences, University of Sydney, Sydney, NSW Australia

2 Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia

3 Australian Antarctic Division, Kingston, TAS, Australia

4 Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, TAS, Australia

5 Schools of Medical and Biological Sciences, University of Sydney, Sydney, NSW, Australia

Background
The heart urchins Abatus ingens and A. shackletoni are ecologically important bioturbators that dominate shallow subtidal areas around Antarctica. To date, there are no published empirical studies on how these echinoids may respond to global change, and polar waters are undergoing carbonate under-saturation earlier than temperate and tropical regions. Studies on Antarctic marine invertebrates are important as they help us predict species response to these changing conditions. In this study, spine growth in juvenile A. ingens and A. shackletoni was investigated in urchins incubated under experimental pCO2 and temperature scenarios predicted by the year 2100.

Methods
Adult A. ingens and A. shackletoni were collected from Heidemann Bay (68° 35’S, 77° 58’E) near Davis Station, East Antarctica, in the 2011 austral summer season (January-February). Juveniles were removed from the parental brood pouch of females and reared for four weeks in a flow-through aquarium system. Temperature controlled seawater (ambient -1°C and 1°C) was injected with CO2 enriched air to create the target pH levels (ambient pH 8.0, pH 7.8, pH 7.6), for a total of six temperature x pH combinations. Spine length in each individual was measured at the start of experiments, and after four weeks exposure.

Findings
Juvenile Abatus reared at pH 7.6 had significantly smaller spines than those in pH 7.8 and ambient control conditions. Spine growth was slower in juveniles of both species exposed to the most extreme treatment combination (1°C/pH 7.6) compared to other treatments. There were no signs of spine dissolution in any treatment.

Conclusions
Slow spine growth in juveniles in pH 7.6 treatments may be due to diversion of energy away from growth to maintain acid-base balance. However, adaptation to the low pH environment within the brood pouch and benthic sediments may explain why juveniles were able to maintain some spine growth in seawater pH levels predicted for 2100.

107. Giant Clams in a Changing Ocean: Effects of Ocean Warming and Acidification on a Solar-powered Bivalve

Gisela Dionísio1,2*, Catarina Santos1,3*, Ricardo Cyrne1*, Mariana Hinzmann2,4, Bernardo A. Duarte5, Ana Lopes1, Vanessa Madeira1, Lidia M. García6, Sara H. García-Morales 6, Jorge Machado4, Rui Rosa1

 

1MARE – Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Cascais, 2750-374, Portugal

2Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

3ICBAS‐UP– Abel Salazar Biomedical Sciences Institute, University of Porto, Porto, 4050-313, Portugal

4CIIMAR– Centre of Marine and Environmental Research, University of Porto, Porto, 4050-123, Portugal

5MARE – Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Campo Grande, Portugal

6 UCM – Facultad de Biología, Universidad Complutense de Madrid, Madrid, 28040, España

 

*Equal contribution

 

Background:

Giant clams are iconic tropical bivalve molluscs enrolled in a rare symbiotic relationship with photosynthetic dinoflagellates (Symbiodinium spp.). Besides their important ecologic role, they have a great cultural and economic value to local human communities. However, populations have been declining over the past decades and their conservation is of considerable management importance. Nonetheless, there is considerable knowledge gap regarding the effects of climate change, with rising temperatures and increasing pCO2 levels, over these species.

Methods:

The present study represents a comprehensive assessment of the physiological responses of the holobiotic system (Tridacna maxima clams and respective symbiotic dinoflagellates) to the foreseen near-future conditions of warming (∆ 3ºC) and high pCO2, with concomitant acidification (ΔpH=0.4). After a two-month acclimation period in a cross-factored design, we evaluated an array of endpoints including: i) respiration and productivity, ii) Symbiodinium cellular conditions, iii) haemolymph cellular and biochemical conditions; iv) shell ultrastructure; v) heat shock response; vi) lipid peroxidation and vii) antioxidative enzymatic activity.

Findings:

The exposure to the experimental conditions triggered deleterious effects in most endpoints. Temperature appeared as the main driver of stress, although effects of acidification were also present and interaction between factors was evident in several cases. The overall fitness of the holobiont was undermined with an evident decline in Symbiodinium populations and cellular damage in the clams, as the defence mechanisms appeared to be insufficient to cope with the new conditions.

Conclusions:

Anthropogenic pressure is already responsible for decline of giant clam populations worldwide and climate change will most likely impose additional stress, undermining the conservation efforts taking place. On the other hand, their unique and charismatic nature may act as a beacon for the conservation of coral reef systems regarding the global change issues.

106. The physiology of Polar cod (Boreogadus saida) in a changing world: Impacts of ocean acidification and warming

Kristina L. Kunz (1,2), Guy Claireaux (3), Hans-Otto Pörtner (2), Rainer Knust (1) & Felix C. Mark (2)*

1 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bentho-Pelagic Processes, Am Alten Hafen 26, D-27568 Bremerhaven, Germany
2 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Integrative Ecophysiology, Am Handelshafen 12, D-27570 Bremerhaven, Germany
3 Université de Bretagne Occidentale, LEMAR (UMR 6539), Unité PFOM, Laboratoire ARN, Centre Ifremer de Brest, 29280 Plouzané, France

Background
The oceans are currently experiencing a distinct warming trend concomitant with increasing levels of PCO2. These trends are expected to be most pronounced in Arctic waters due to the high solubility of CO2 in the cold and decreasing salinities in surface waters. Low natural temperatures in the Arctic imply strong adaptation of Arctic species along with reduced tolerance to changing abiotic conditions as a trade-off. Polar cod (Boreogadus saida) is a key species and an important protein source in the Arctic food chain. The aim of the present study is the investigation of several components of the energy budget of Polar cod under current and projected water conditions in order to evaluate its future competitive strength.

Methods
We incubated Polar cod under different combinations of temperature (0, 3, 6, 8°C) and PCO2 (390, 1,170 µatm) over four months and determined growth performance and feed consumption. After their long-term incubation, swimming performance, active (AMR) and standard metabolic rate (SMR) were measured.

Findings
The impact of hypercapnia on the performance of Polar cod was less pronounced compared to temperature effects. Among investigated parameters, swimming performance was the most sensitive towards ocean acidification, indicated by a lower maximum swimming speed. High PCO2 caused a non-significant trend for impaired growth in Polar cod, most pronounced at the optimum temperature for growth (6°C) under control conditions. Despite low feed intake at 0°C, feed conversion efficiency was highest at this temperature. Both AMR and SMR were significantly enhanced at the highest investigated temperature (8°C).

Conclusions
Our results suggest a high sensitivity of Polar cod towards ocean acidification and warming. Decreasing growth rates and swimming performance may parallel a decrease in abundance, especially when OA is combined with further challenges, such as a decline in under-ice habitats and increased Atlantification of Arctic waters.

105. Behaviour of Atlantic cod (Gadus morhua) is more resilient to ocean warming and acidification than that of Polar cod (Boreogadus saida)

Matthias Schmidt (1), Hans-Otto Pörtner (1), Christian Bock (1)*, Daniela Storch (1)

1 Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany

Background
Ocean acidification (OA) as projected for the year 2100 strongly alters the behaviour of tropical and temperate marine teleost and elasmobranch species with potential impacts for individual fitness and impacts at the ecosystem level. We investigated whether OA changes behavioural laterality and spontaneous activity of two co-occurring cold-water adapted teleost species from Svalbard, Polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua). We further tested for effects of temperature, as the Arctic Ocean will warm in parallel to the acidification process.

Methods
B. saida and G. morhua were incubated for 6 weeks at 2 different CO2 concentrations (current day and as projected for the year 2100) and at 4 different temperatures specific for their thermal window (0,3,6,8°C for B. saida and 3,8,12,16°C for G. morhua, respectively). Behavioural laterality of animals was tested using a Detour test and spontaneous activity was quantified through estimation of crossed grid-lines over a defined period of time.

Findings
OA significantly affected behavioural laterality of B. saida but not that of G. morhua. Spontaneous activity of B. saida, but not of G. morhua was significantly dependent on environmental temperature. Interactive effects of ocean acidification and temperature were not detected.

Conclusions
The behaviour of B. saida may be more vulnerable in a more acidified, warmer future ocean than the behaviour of G. morhua. Due to ocean warming, G morhua currently moves northward into the distribution area of B. saida with potential for competition. Behavioural resilience of G. morhua to future OA scenarios indicates that this invading species might out-compete native B. saida in those areas where the two species will co-exist.

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