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Climate, ocean acidification, and the changing oceans

Room: Carron B     2014-08-18; 11:00 - 13:00

NB: Unless specified otherwise, presentations are 15 minutes in length, and speed presentations are 5 mins in length.

Chair(s)/Moderator(s): Sunday, Jennifer

C4.1  11:00  Climate change for mussel reefs hangs by a thread. Kent, FEA *, Heriot-Watt University; Last, K Scottish Association for Marine Science; Sanderson, WG Heriot-Watt University;

Abstract: Biogenic reefs, such as those formed by horse mussels (Modiolus modiolus) are biodiversity hotspots, and therefore recognized for their conservation importance. M. modiolus habitats are defined as “reefs” in Marine Protected Areas under the EU Habitats Directive. Highlighting and quantifying the services provided by different marine ecosystems shows the value of different habitats and species to society, which can support decision making and marine spatial planning. The objectives of this study were to measure sedimentation in situ, and then to test if M. modiolus biodeposition rates (faeces and pseudofaeces) were modified by an increase in temperature. A method was developed to collect sediment and biodeposits on a M. modiolus reef using portable experimental units that were deployed by SCUBA divers. Controls units accounted for background sediment deposition using dead mussels shells held together as proxy for living reef matrix. In the laboratory, Vortex Resuspension Tanks (VoRTs) were used to maintain M. modiolus under controlled conditions where the seawater temperature could be adjusted. The results provide the first evidence of the scale at which M. modiolus are able to provide ecosystem services, such as habitat provision and sediment sequestration in the North East Atlantic. Increased seawater temperature can modify the function of M. modiolus, and therefore change the way that biogenic habitats provide benefits to society.

C4.2  11:15  Ecological traits and climate velocity explain range shifts in a climate warming hotspot. Sunday, JS *, University of British Columbia; Bates, AE University of Southampton; Pecl, GT University of Tasmania; Frusher, S University of Tasmania; Hobday, AJ CSIRO Marine and Atmospheric Research; Hill, N University of Tasmania; Holbrook, N University of Tasmania; Edgar, GJ , University of Tasmania;

Abstract: Although many marine species have moved to higher latitudes as a response to climate warming, there is little information on species’ ecological traits that might explain the vast variation in species responses. Here we compile range shifts of marine coastal species in a climate change hotspot to identify species traits that explain variation in rates of range extensions over the last half-century. We find the expected rate of shift based on climate velocity and the continental margin explains the majority of variation in the data. Among fishes, extension rate was positively related to latitudinal range size, and negatively related to trophic level. Remarkably, dispersal potential had a low ability to explain range extension rates, with low-dispersal species among those with the greatest extension rates. The importance of range size and trophic level in explaining range shifts suggest that species with broad dietary and habitat requirements expand faster in a marine climate warming hotspot.

C4.3  11:30  The effects of coral declines and fisheries on reef structural processes and coral reef habitat. Januchowski-Hartley, FA *, University of Exeter; Perry, C University of Exeter; McClanahan, TR Wildlife Conservation Society;

Abstract: Anthropogenic pressures on coral reefs have led to global declines in the abundance and community composition of both corals and fishes. While these changes in biota can lead to new alternative stable states and novel ecosystem configurations, their implications for structural processes underpinning the long term persistence of coral reefs – the maintenance of the carbonate framework – are little considered. By using a novel census based approach that combines estimates of the abundance of carbonate producing (e.g., corals, coralline algae) and bioeroding (e.g., parrotfish, urchins) species with rates of carbonate deposition and bioerosion, we are able to estimate the net accretional/erosional state of coral reefs. Because this methodology uses a census based approach, similar to commonly used underwater visual census methods, it can be easily adapted for data on coral cover, fish biomass etc. that had originally been collected for other purposes. We applied this approach to coral reefs inside and outside protected areas on the Kenyan coast to estimate their current erosional state. We also identify the contribution of various eroding and bioeroding guilds, and use previously collected time series data on coral cover, fish abundance and fisheries status to identify trends within these guilds and which aspects of the ecosystem need to be considered to maintain the structural integrity of coral reefs.

C4.4  11:45  Multiple stressors in a warming ocean: Using thermal performance curves to improve predictions of non-additive outcomes. Kroeker, KJ *, University of California, Davis; Harley, CDG University of British Columbia; Bible, JM University of California, Davis; Cheng, BS University of California, Davis; Kordas, RL University of British Columbia; Miller, SH University of California, Davis;

Abstract: Climatic warming is occurring across a mosaic of human activities that impact marine species and ecosystems, however our ability to predict the combined impacts of multiple stressors is limited due to the high potential for non-additive interactions. Recommendations for climate adaptation strategies already include the mitigation of local stressors to promote resilience, but we lack much of the necessary information to prioritize under what conditions conservation and management investments may be most effective. Species’ responses to temperature may provide a framework for predicting non-additive interactions between warming and other stressors that can be used to guide local stressor mitigation. Here, we use meta-analysis to examine the interactive effects of elevated temperature and other stressors in factorial laboratory experiments with marine species. We find that non-additive interactions can in part be explained by species’ responses to near-future warming scenarios (e.g., whether species experience increased vs. decreased growth in response to the warming treatment). While there is important variability among different stressor combinations and species, this research highlights how future warming in the marine environment can influence vulnerability to other stressors.

C4.5  12:00  Using a novel, multidimensional coral health index (CHI) to assess human and natural impacts on Maldivian coral reefs. Lewis, LS *, Scripps Institution of Oceanography; Harris, JL Scripps Institution of Oceanography; Smith, JE Scripps Institution of Oceanography; Sandin, SA Scripps Institution of Oceanography;

Abstract: Ecosystem health is multifaceted, particularly on coral reefs. The Coral Health Index (CHI) is a simple, multivariate tool that combines data on benthic, fish, and microbial communities into a normalized index of ecosystem health. We used CHI to establish a baseline and explore variation in coral reef health throughout Lhaviyani, a sparsely-populated atoll in the Maldives. Working from a new research lab (Korallion), we assessed ecological health across 10 islands throughout the atoll. Specifically, we examined the effects of (1) local human population, (2) reef exposure, and (3) orientation on benthic, fish, and microbial communities. We then calculated a CHI score, comparing ecosystem health among Lhaviyani's reefs and with coral ecosystems in the Central Pacific. Calcifier cover on islands ranged from 12-55%. Exposure affected coral communities, with lagoonal and oceanic reefs dominated by branching and massive corals, respectively. Fish communities were dominated by planktivores, and biomass of large fishes (>20 cm) was low overall. Microbe densities were < 30 CFU/mL (i.e. “very healthy”). No effects of population, exposure or orientation on any of the three CHI components were detected. The atoll’s intermediate coral cover, low reef fish biomass, and high water quality resulted in a “fair” to “healthy” CHI score, comparable to other sparsely inhabited islands. We suggest that CHI is an informative, accessible metric for monitoring and comparing reef health globally.

C4.6  12:15  Anthropogenic facilitation and impacts of invasive Asian shore crab around Long Island, NY, USA. Freeman, AS *, Adelphi University; Blakeslee, A. Long Island University Post; Fowler, A South Carolina DNR; Frischeisen, A Adelphi University; Kulins, S Adelphi University; Taub, E. Adelhi University;

Abstract: We present a series of studies investigating how environmental pollutants and invasive species may interact to further degrade coastal estuaries in eastern North America. Since its introduction prior to 1988, the Asian shore crab (Hemigrapsus sanguineus) has become well established in eastern North America. The invader occupies similar estuarine habitats once occupied by native, panopeid mud crabs (Panopeus herbstii and Eurypanopeus depressus). An invasive, rhizocephalan (Loxothylacus panopaei) that parasitizes native panopeids was recently discovered in the region and may facilitate the invasion of Hemigrapsus. We have found that the parasite currently has a limited distribution and, where it does impact native panopeids, Hemigrapsus does not benefit from reduced competition with native panopeids. We found that Hemigrapsus are less affected by the pesticide malathion than native panopeid crabs, suggesting environmental pollutants may facilitate the invasive crab’s progress. Finally we document the impacts of these native and invasive crabs on hard-substrate fouling communities. We find that these fouling communities are heavily dominated by invasive tunicates that may be favored by interactions with the invasive Hemigrapsus.

C4.8  12:30  Tough as a rock-boring urchin: Adult Echinometra mathaei from the Red Sea show high resistance to ocean acidification over long term exposures. Hazan,Y *, Ben Gurion University of the Negev, Israel and the Interuniversity Institute for Marine Sciences in Eilat, Israel;

Abstract: Rising atmospheric CO2 levels due to anthropogenic emissions are acidifying the world’s oceans and changing the seawater chemistry. The impacts of these changes on the marine biota are still largely unknown, however rapidly accumulating data suggest they will have profound effects on all ecosystem levels. This study examined the performance of multiple physiological processes in adult Echinometra mathaei sea urchins over an 11 month incubation under near future ocean acidification conditions. Somatic growth, gonadal growth, gametogenesis and skeletal microstructure were compared between two pCO2 treatments: high (1433±19μatm; pH(NBS) 7.7) and control (435±5μatm; pH(NBS) 8.1). Significant somatic and gonadal growth occurred with no differences between the treatments. Additionally, the urchins in both treatments completed a full reproduction cycle typical of natural populations with no detectable effect of the high pCO2 treatment. Furthermore, scanning electron microscopy images of urchins tests and spines revealed no signs of acidosis effects such as skeletal dissolution, widened stereom pores or non-smoothed structures. No significant impact of high pCO2 on any of the examined processes indicates high resistance of adult Echinometra mathaei to ocean acidification. With respect to other findings in this area, the outcome of this study can be seen as evidence for the complicated and diverse responses of echinoids to predicted environmental changes.

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