An integrated view of climate sensitivity in marine organisms: The need for proxies indicating molecular to ecosystem-level changes

Hans-O. Pörtner

Climate change effects on marine ecosystems predominantly involve effects of temperature, hypoxia and CO₂. All life forms respond to these drivers, potentially following common, insufficiently understood principles. In animals the concept of oxygen and capacity dependent thermal tolerance (OCLTT) appears as a suitable integrator of various effects, across levels of biological organisation. Recent studies confirm OCLTT involvement in changing species abundance, biogeographical ranges, phenology and species predominance. Performance capacity set by aerobic scope and energy budget, building on baseline energy turnover, link fitness (within thermal window) and functioning at ecosystem level. In variable environments like the intertidal zone, animals also exploit their capacity for passive tolerance. The complexity of molecular adjustments involved in long-term adjustments to climate requires further analysis. While presently the temperature signal appears predominant in the field, observations may well include emerging effects of other stressors, acting synergistically by narrowing the aerobic OCLTT window. OCLTT may link apparently disjunct effects of ocean warming, acidification and hypoxia. In brief, warming induced CO₂ accumulation in body fluids links to the effects of ocean acidification mediated by the weak acid distribution of CO₂. Temperature induced hypoxemia links to the hypoxia sensitivity of thermal tolerance. The present paper discusses the suitability of various proxies indicating the temperature dependent effects of climate related stressors. Mechanism-based modelling efforts are then needed to develop reliable, organism to ecosystem projections of future change.

Modeling krill 'hotspots' in the central California Current: Results from variation in diel vertical migration schemes

Jeffrey G. Dorman, Ramona L. Zeno, Jarrod A. Santora and William J. Sydeman

The spatial organization of prey resources is critical to the foraging success of predators. In the central California Current, krill form a key prey resource for a diverse array of predators from fish to seabirds and marine mammals. Previous research has shown that krill occur in large patches (or ‘hotspots’) of abundance that are typically found downstream from centers of upwelling in this system (Santora et al. 2011). In this study, we use a coastal ocean model (ROMS), integrated with an individual-based model parameterized for Euphausiapacifica, to investigate if we could reproduce known krill ‘hotspots’ in our time-space domain. In our experiment, we compared the resulting distribution of krill particles while varying the upper limit of vertical migration from 0 to 40 meters. Based on 90-day model runs initiated on February 15 over 9 years (2000-2008), we found that some of our known hotspots were better reproduced when the upper limit of vertical migration was deeper in the water (40 meters). We also found that krill particles were rarely retained in hotspots over the course of an entire model run and that particle retention time was greater in certain hotspots than in adjacent non-hotspot regions. This study highlights the role of transport and vertical migration in the maintenance of krill hotspots along the central California coast. The lack of particle retention in certain hotspots highlights the potential role of other factors (behavior, reproduction, predation, etc.) in the formation and maintenance of krill spatial structure in the California Current.

Seasonal changes in the zooplankton community and number of generations per year of small copepods in Ishikari Bay, Sea of Japan

Daichi Arima¹, Atsushi Yamaguchi¹, Yoshiyuki Abe¹, Kohei Matsuno², Rui Saito³, Hiroki Asami⁴, Hiroshi
Shimada⁴ and Ichiro Imai¹

Information on the annual reproductive cycle of mesopelagic fishes has been limited in the western North Pacific, despite their ecological importance.. The Kuroshio region is an important spawning ground for various species of mesopelagic fishes. To describe the reproductive seasonality, we examined the seasonal occurrence patterns of the mesopelagic fish larvae on the continental slope in Tosa Bay which is strongly influenced by the Kuroshio, based on monthly samples collected from January 2001 to December 2004. In total, 2,558 mesopelagic fish larvae occurred, with peak abundance during May to June. Larvae of the dominant families Myctophidae, Sternoptychidae, Gonostomatidae, Bathylagidae, and Phosichthyidae were represented by 26 species (or types) belonging to 18 genera. The twelve most abundant species accounted for 96.9% of the total catch. The seasonal occurrence patterns of these larvae were categorized into five groups in accordance with physical properties of the water column: Winter (Notoscopelus japonicus and Lipolagus ochotensis); Spring (Symbolophorus evermanni and Maurolicus japonicus); Early summer (Myctophum asperum and Diaphus stubby type); Autumn (Lampanyctus sp. A, Cyclothone spp., and Sigmops gracile); and Year-round (Vinciguerria nimbaria, Diaphus slender type, and Diogenichthys atlanticus) groups. No significant difference was observed in the months of peak abundances of these larvae during the four years, suggesting that each species has a fixed seasonal pattern of reproduction. The various patterns of seasonal occurrence would result in seasonal habitat segregation of the larvae among species, possibly reducing intraspecific competition for food resources in the oligotrophic waters of the Kuroshio.

Linking recruitment synchrony to environmental variability

Megan M. Stachura¹, Timothy E. Essington¹, Nathan J. Mantua², Anne B. Hollowed³, Melissa A. Haltuch⁴, Paul
D. Spencer³, Trevor A. Branch¹ and Miriam J. Doyle⁵

We investigated the hypothesis that synchronous recruitment is due to a shared susceptibility to environmental processes using stock-recruitment residuals for 52 marine fish stocks within three Northeast Pacific large marine ecosystems: the Eastern Bering Sea and Aleutian Islands (BSAI), Gulf of Alaska (GOA), and California Current (CC). We identified moderate coherence in terms of exceptionally strong and weak year classes and significant distributions of cross-stock correlation. Based on evidence of synchrony from these analyses, we used Bayesian hierarchical models to relate recruitment for groups of stocks with similar susceptibility to environmental processes to environmental covariates. There were consistent relationships among stocks to the covariates, especially within the GOA and CC. Within the GOA the best model included Northeast Pacific sea surface height data as predictor of recruitment, and was particularly strong for stocks dependent on cross-shelf transport during the pelagic larval phase for recruitment. In the CC the best-fitting model included San Francisco sea level height data as predictors, with higher recruitment for many stocks corresponding to high sea level the year before spawning and low sea level the year of spawning. For the BSAI stocks the best model included several environmental variables as covariates and there was some consistency in sensitivity to these variables. Future research may be able to utilize these cross-stock environmental influences, in conjunction with a mechanistic understanding of ecological processes across early life history stages at appropriate temporal and spatial scales, to improve identification of environmental drivers of recruitment.

Development of the 3-D growth prediction model for Japanese scallop in Funka Bay, Japan

Yang Liu¹, Sei-Ichi Saitoh¹, Yu Ihara², Toru Hirawake¹, Katsuhisa Baba³ and Kanamori Makoto³

Information on larval fish ecology and early life history is very important for resource management and the conservation of marine biodiversity. In addition, larval recruitment of demersal fishes determines adult distribution patterns. Moray eels are important elements in tropical to temperate coastal ecosystems due to their role as a higher-level predator. Some species are reported to spawn in coastal areas, however, their larval ecology and early life histories are mostly unknown. Therefore, we first examined the distribution patterns of the leptocephali of different species or types in the Indo-Pacific to estimate the general early life history of moray eels. A total of 914 specimens of muraenid leptocephali were collected across a wide range from the western North Pacific to the western Indian Ocean. They were separated into at least 75 species based on morphology and genetic analysis. All species were distributed in the open ocean. The leptocephali of two species, Gymnothorax minor and G. pseudothyrsoideus were also collected from coastal areas. The specimens collected at moderate distances from coastal areas were small to large size. But the specimens collected at long distances from coastal areas were all large size. Therefore, we estimated that small leptocephali born in the coastal areas were dispersing widely across the open ocean, and then their leptocephali returned to the coastal area after growing. Further research is necessary to clarify their dispersal mechanisms and the timing of when they leave the open ocean, and this will be investigated using otolith microchemistry with LA-ICP-MS.

Oral, BIO/FIS/MEQ/TCODE/FUTURE Topic Session

Assessing direct and indirect risk from human activities to significant ecosystem components in the Northeast Pacific

Cathryn Clarke Murray¹, Megan E. Mach², Rebecca G. Martone², Gerald G. Singh³, Kai M.A. Chan³ and Miriam O⁴

Despite the importance and irreplaceability of coastal ecosystems and the services they provide, degradation and loss of coastal ecosystems is intense and increasing worldwide. This is in large part due to a lack of understanding of how multiple human activities cumulatively affect ecological systems. Given the complexity of ecosystems and the shifting role of species in response to global change, considering both direct and indirect impacts to ecosystem components and indicators of ecosystem health is a priority for scientists and managers. Risk assessment is emerging as a tool for assessing complex relationships between multiple human activities and ecosystems. Yet, the risk assessment literature thus far has not incorporated how ecological components interact with other species or populations, and how risk results from these interactions. Without this knowledge, we cannot easily predict how human activities will impact ecosystem function, whether via direct impacts to ecological components and/or indirectly by affecting supporting species or processes. Here we describe a probabilistic risk assessment method to assess both direct and indirect risk to significant ecological components by incorporating habitat and trophic linkages. This methodology was applied to significant ecological components of the Pacific North Coast Integrated Management Area in order to estimate cumulative risk from land, coastal and ocean-based human activities. A comprehensive estimate of risk to ecological components and indicators of ecosystem health can facilitate ecosystem-based management and the sustainable use of coastal resources.

Poster, MEQ/FUTURE Topic Session

Ship paint as a new input source of floating microplastics in surface microlayer

Young Kyoung Song^1,2, Won Joon Shim^1,2, Mi Jang^1,2, Sang Hee Hong^1,2 and Gi Myung Han¹

Small sized and low specific gravity microplastics are expected to be accumulated within the surface microlayer (SML) of water due to SML’s high surficial tension. In this study, plastic-like particles were identified by FT-IR microscope in SML from ten stations of southern coast of South Korea in May and July of 2012. Abundances of microplastics are in the range of 68-473 particles/L in May and 60-253 particles/L in July. Results from FTIR identification showed that microplastics in the SML contains at least two types of polymers in fragment; 1) polyester (soybean oil modified phthalic alkyd) and 2) poly (acrylate:styrene) copolymer. These co-polymer types accounted for over 90% of total microplastics abundances and are known to be used in ship paint, coating, pharmaceutical, oil industry, textile finishing, etc. Ship paint was suspected as an origin of the co-polymer fragments, considering their distinct green or blue color as well as thousands of fishing boats registered in the study area. The FT-IR spectrums of the major microplastic co-polymer fragments in the SML and the ship paint chips collected from several boat hulls in the study area matched identically. It indicates that two co-polymer particles are mainly originated from ship paints applied to ship hulls. However, it is unclear, yet that the copolymer fragments were introduced to surface water directly from during ship moving and (or) ship repairing in shipyards and ports. Further study is required to investigate environmental and ecotoxicological consequences of co-polymer fragments and their associated toxic chemicals in SML.

Invited, POC/BIO/MONITOR/FUTURE Workshop

How eastern Bering Sea climate variability affects the distribution of walleye pollock early life stages

Colleen M. Petrik¹, Janet T. Duffy-Anderson², Franz Mueter³, Katherine Hedstrom⁴, Seth Danielson⁵ and Enrique
Curchitser⁶

We present a dynamical method for examining the mechanisms underlying correlative relationships in physicalbiological
datasets. Specifically, we will address the correlation between thermal conditions and the distribution of walleye pollock early life stages in the eastern Bering Sea. The eastern Bering Sea recently experienced a prolonged warm period followed by a prolonged cold period. Analyses of observational data indicated that spatial distributions of walleye pollock early life stages were influenced by both broad- and fine-scale variables, with the greatest amount of variation in abundance explained by temperature over wind, spawning stock biomass, and zooplankton biomass. Under warmer-than-average thermal conditions, distributions were shifted to the east, suggesting a relationship with the predominant wind patterns over the shelf in these years. Additionally, roe-fishery data indicated a spawning time delay by as much as one month when temperatures were colder than average. We developed a coupled biological-physical model (ROMS-TRACMASS) to examine how variable physical forcing affects the spawning, transport, and distribution of walleye pollock early life stages in the eastern Bering Sea. The individual-based biophysical model is being used to test the effects of atmospheric (wind), oceanographic (ice, water column temperature), and biological (time and location of spawning) conditions on the distribution, growth, and transport of walleye pollock eggs and larvae. Model results will help elucidate the dominant physical mechanisms responsible for observed changes. A strength of this modeling approach is the ability to individually test mechanisms to quantitatively assess the impact of each on the distribution of pollock.

Hiromichi Ueno

Hydrographic data measured for 50 years along Line P between the North American west coast and mid Gulf of Alaska as well as data from profiling float observations were analyzed to study the formation and variation of temperature inversions in the eastern subarctic North Pacific. Remarkable decadal to inter-decadal variation was observed in the magnitude of temperature inversions. This variation was mostly attributed to the variation of southward Ekman transport, eastward geostrophic transport and surface cooling.

Oral, BIO/POC/TCODE/MONITOR/FUTURE Topic Session

An improvement of reproducibility of Pacific decadal oscillation in CMIP5

Youngji Joh¹, Chan Joo Jang¹, Minho Kwon¹, Ho-Jeong Shin¹ and Taewook Park²

The Pacific decadal oscillation (PDO), defined as the first empirical orthogonal function mode of North Pacific sea surface temperature (SST), could affect variability of marine ecosystems as well as the climate system in the North Pacific. We evaluate PDO reproducibility simulated from coupled general circulation models (CGCMs) of phase 3 and 5 of the Coupled Model Intercomparison Project (i.e. CMIP3 and CMIP5, respectively) by investigating the interaction between PDO and El Niño - Southern Oscillation (ENSO), and teleconnections between extra tropics and tropics. PDO comparison between the CGCM simulation and observation during the period 1900-1998 shows that the PDO reproducibility has improved in CMIP5 relative to CMIP3. To assess how PDO reproducibility can be improved in CMIP5, sensitivity of precipitation to tropical SST and representation of the Pacific/North America pattern were analyzed. The CGCMs in CMIP5 show enhanced simulations of ENSO and teleconnections agreeing more with observations than those in CMIP3. Based on observations, anomalous warming of the tropical Pacific during El Niño events enhances tropical precipitation with energy transport from ocean to atmosphere and causes atmospheric waves to propagate into the extra tropics. Therefore, it is important to realistically simulate a response of precipitation in the tropical Pacific to SST and formation of planetary waves in appropriate locations. Our findings suggest that enhancement of ENSO reproducibility and teleconnections from tropics to extratropics contribute to the improvement of PDO reproducibility in CMIP5 CGCMs.

Poster, MONITOR Topic Session

Geographical shift of warm water species distribution in western subarctic North Pacific based on CPR sample during 2001-2010

Tomoko M. Yoshiki¹, Sanae Chiba², Tadafumi Ichikawa¹, Hiroya Sugisaki³ and Sonia Batten⁴

Spatial and temporal variation of copepod community structure, abundance and biodiversity was examined in the western subarctic North Pacific (40-55ºN, 142-170ºE) during 2001-2010. Continuous Plankton Recorder (CPR) observational data during summer season (June and July) was analyzed. The warm water species group increased in abundance and was highest in 2009-2010, while cold water species abundance decreased. Mean copepod species diversity increased after 2006. We found a significant positive correlation between warm water species abundance and SST, and also between warm water species abundance and copepod diversity in each sampling location. The most abundant warm water species was Calanuspacificus which accounted for more than 90% of the total warm water species abundance, and which occurred in higher SST area (>7.5ºC). Although a small number of C. pacificus occurred only in an area south of 47ºN during 2001-2005, the distribution extended to the northern area than above 50ºN after 2006. Also it was more abundantly observed over almost the whole sampling location between 40-52ºN in 2009-2010. The SST in the North Western Pacific was warmer during 2006-2010 than during 2001-2005, and this agrees with the PDO pattern. The SST increase of 2006-2010 was considered to cause the geographical shift of warm water species distribution, and subsequently, the northward extension of the warm species was considered to be a one of the cause of the higher biodiversity.

Oral, FIS/TCODE Topic Session

Modelling the effects of density-dependent mortality in juvenile red snapper caught as bycatch in Gulf of Mexico shrimp fisheries: Implications for management

Robyn E. Forrest¹, Murdoch K. McAllister², Steven J.D. Martell²* and Carl J. Walters²

Density-dependent mortality of juvenile fishes is a key population regulation mechanism that is usually assumed to occur before fish recruit to fisheries. When density-dependent mortality occurs simultaneously with bycatch of juvenile fish but is not accounted for in stock assessments, estimates of population size and fishery reference points may be biased. This paper develops an instantaneous, age-structured model accounting for simultaneous density-dependent mortality and bycatch in age-0 red snapper (Lutjanus campechanus), using equations derived from the Beverton-Holt stock-recruit function. Two simplified Bayesian models (with and without post-recruitment density-dependent mortality) are fitted to simulated indices of abundance and age composition data to explore the estimability of model parameters under different amounts of process and observation error, and also to illustrate policy implications of model mis-specification in terms of timing of density-dependent processes. Results show that failure to account for post-recruitment density-dependent mortality in stock assessments can lead to overestimation of true abundance, recovery potential and the fishery reference points MSY and B_MSY. These analyses also illustrate the problematic nature of defining and calculating reference points in the presence of numerous sources of mortality that affect different demographic components of the population. Because the model without post-recruitment density-dependence is a special case of the model with density-dependence, we suggest that it may be advisable to use the latter model if there is a possibility that post-recruitment density-dependent mortality is a factor governing population dynamics, although further simulation testing is recommended.
†Forrest, R.E., McAllister, M.K., Martell, S.J.D, Walters, C.J. 2013. Modelling the effects of density dependent
mortality in juvenile red snapper caught as bycatch in Gulf of Mexico shrimp fisheries: implications for
management. Fisheries Research, 146: 102-120