Proceedings of the PICES/CoML/IPRC Workshop on Impact of Climate Variability on Observation and Prediction of Ecosystem and Biodiversity Changes in the North Pacific

Table of Contents [pdf, 0.09 Mb] Section I - Presentations and Discussions at Plenary Sessions Introduction and Overview of Workshop Objectives [pdf, 0.07 Mb] Plenary Session Presentations [pdf, 2.23 Mb] Reports of the Breakout Group Discussions [pdf, 0.43 Mb] Closing Plenary Discussion and Recommendations [pdf, 0.11 Mb] Section II - Extended Abstracts of Individual Presentations at Breakout Group Sessions Breakout Group 1: Physical/Chemical Oceanography and Climate [pdf, 6.14 Mb] Breakout Group 2: Phytoplankton, Zooplankton, Micronekton and Benthos [pdf, 28.14 Mb] Breakout Group 3: Fish, Squid, Crabs and Shrimps [pdf, 4.30 Mb] Breakout Group 4: Highly Migratory Fishes, Seabirds and Marine Mammals [pdf, 6.27 Mb] Appendix 1. Workshop agenda [pdf, 0.15 Mb] Appendix 2. List of participants [pdf, 0.13 Mb] (Document pdf contains 216 pages)

Report of the PICES-STA Workshop on Monitoring Subarctic North Pacific Variability

The PICES Science Board and the Science and Technology Agency of Japan held a Workshop on Monitoring Subarctic North Pacific Vaiability,October 22-23,1994, in Nemuro,Hokkaido,Japan,in conjunction with the PICES Third Annual Meeting. The Workshop was not intended to discuss process studies or to review the science of the subaractic Pacific,but rather to focus on the longterm monitoring programs required for assessment of the physical and ecological responses to long-term forcing,both natural and man-made. (PDF contains 90 pages)

Variability of Temperature and Salinity in the Middle Atlantic Bight and Gulf of Maine

Monitoring of the waters of the Middle Atlantic Bight and Gulf of Maine has been conducted by the MARMAP Ships of Opportunity Program since the early 1970's. Presented in this atlas are portrayals of the temporal and spatial patterns of surface and bottom temperature and surface salinity for these areas during the period 1978-1990. These patterns are shown in the form of time-space diagrams for single-year and multiyear (base period) time frames. Each base period figure shows thirteen-year (1978-1990) mean conditions, sample variance in the form of standard deviations of the measured values, and data locations. Each single-year figure displays annual conditions, sampling locations, and departures of annual conditions from the thirteen-year means, expressed as algebraic anomalies and standardized anomalies. (PDF file contains 112 pages.)

Seasonal Climatologies and Variability of Eastern Tropical Pacific Surface Waters

Interannual variability caused by the El Nino-Southern Oscillation in the eastern tropical Pacific Ocean (ETP) is analogous to seasonal variability of comparable magnitude. Climatological spatial patterns and seasonal variability of physical variables that may affect the ETP ecosystem are presented and discussed. Surface temperature, surface salinity, mixed layer depth, thermocline depth, thermocline strength, and surface dynamic height were derived from bathythermograph, hydrocast, and CTD data. Surface current velocity, divergence, and upwelling velocity were derived from ship drift reports. Surface wind velocity, wind stress, wind divergence, wind stress curl, and Ekman pumping velocity were derived from gridded pseudostress data obtained from Florida State University. Seasonal maps of these variables, and their deviations from the annual mean, show different patterns of variation in Equatorial (S°S-SON) and Tropical Surface Water (SOlS0N). Seasonal shifts in the trade winds, which affect the strength of equatorial upwelling and the North Equatorial Countercurrent, cause seasonal variations in most variables. Seasonal and interannual variability of surface temperature, mixed layer depth, thermocline depth and wind stress were quantified. Surface temperature, mixed layer depth and thermocline depth, but not local wind stress, are less variable in Tropical Surface Water than in Equatorial Surface Water. Seasonal and interannual variability are close to equal in most of the ETP, within factors of 2 or less. (PDF file contains 70 pages.)

Food habits and dietary variability of pelagic nekton off Oregon and Washington, 1979-1984

The food habits of 20 species of pelagic nekton were investigated from collections made with small-mesh purse seines from 1979-84 off Washington and Oregon. Four species (spiny dogfish, Squalus acanthias; soupfin shark, Galeorhinus zyopterus; blue shark, Prionace glauca; and cutthroat trout, Salmo clarki) were mainly piscivorous. Six species (coho salmon, Oncorhynchus kisutch; chinook salmon, O. tshawytscha; black rockfish, Sebastes melanops; yellowtail rockfish, S. f1avidus; sablefish, Anoplopoma fimbria; and jack mackerel, Trachurus symmetricus) consumed both nektonic and planktonic organisms. The remaining species (market squid, Loligo opalescens; American shad, Alosa sapidissima; Pacific herring, Clupea harengus pallasi; northern anchovy, Engraulis mordax; pink salmon, O. gorbuscha; surf smelt, Hypomesus pretiosus; Pacific hake, Merluccius productus; Pacific saury, Cololabis saira; Pacific mackerel, Scomber japonicus; and medusafish, Icichthys lockingtom) were primarily planktonic feeders. There were substantial interannual, seasonal, and geographic variations in the diets of several species due primarily to changes in prey availability. Juvenile salmonids were not commonly consumed by this assemblage of fishes (PDF file contains 36 pages.)

Mortality, growth and growth rate variability of striped bass larvae in Chesapeake Subestuaries

In this report we develop age-length keys and derive age-frequency data. We estimate striped bass and white perch mortality and growth rates, based on the otolith-aging analysis. We also report on hatch-date frequencies of striped bass and white perch larvae, and we discuss environmental effects on recruitment potential.

Hypoxic and low pH water in the nearshore marine environments of Monterey Bay, California: characterizing a decade of oxygen and pH, and drivers of variability.

A decade-long time series recorded in southern Monterey Bay, California demonstrates that the shallow, near-shore environment (17 m depth) is regularly inundated with pulses of cold, hypoxic and low pH water. During these episodes, oxygen can drop to biologically threatening levels, and pH levels were lower than expected. Weekly water chemistry monitoring revealed that the saturation state of aragonite (the more soluble form of calcium carbonate) was often below saturation and had a moderate positive relationship with pH, however, analytical and human error could be high. Pulses of hypoxia and low pH water with the greatest intensity arise at the onset of the spring upwelling season, and fluctuations are strongly semidurnal (tidal) and diurnal. Arrival of cold, hypoxic water on the inner shelf typically occurs 3 days after the arrival of a strong upwelling event and appears to be driven by upwelling modulated by internal tidal fluctuations. I found no relationship between the timing of low-oxygen events and the diel solar cycle nor with terrestrial nutrient input. These observations are consistent with advection of hypoxic water from the deep, offshore environment where water masses experience a general decline of temperature, oxygen and pH with depth, and inconsistent with biochemical forcing. Comparisons with concurrent temperature and oxygen time series taken ~20 km away at the head of the Monterey Canyon show similar patterns but even more intense hypoxic events due to stronger semidiurnal forcing there. Analysis of the durations of exposure to low oxygen levels establishes a framework for assessing the ecological relevance of these events. Increasing oceanic hypoxia and acidification of both surface and deep waters may increase the number, intensity, duration and spatial extent of future intrusions along the Pacific coast. Evaluation of the resiliency of nearshore ecosystems such as kelp forests, rocky reefs and sandy habitats, will require consideration of these events.

Season- and depth-dependent variability of a demersal fish assemblage in a large fjord estuary (Puget Sound, Washington)

Fjord estuaries are common along the northeast Pacific coastline, but little information is available on fish assemblage structure and its spatiotemporal variability. Here, we examined changes in diversity metrics, species biomasses, and biomass spectra (the distribution of biomass across body size classes) over three seasons (fall, winter, summer) and at multiple depths (20 to 160 m) in Puget Sound, Washington, a deep and highly urbanized fjord estuary on the U.S. west coast. Our results indicate that this fish assemblage is dominated by cartilaginous species (spotted ratfish [Hydrolagus colliei] and spiny dogfish [Squalus acanthias]) and therefore differs fundamentally from fish assemblages found in shallower estuaries in the northeast Pacific. Diversity was greatest in shallow waters (<40 m), where the assemblage was composed primarily of flatfishes and sculpins, and lowest in deep waters (>80 m) that are more common in Puget Sound and that are dominated by spotted ratf ish and seasonally (fall and summer) by spiny dogfish. Strong depth-dependent variation in the demersal fish assemblage may be a general feature of deep fjord estuaries and indicates pronounced spatial variability in the food web. Future comparisons with less impacted fjords may offer insight into whether cartilaginous species naturally dominate these systems or only do so under conditions related to human-caused ecosystem degradation. Information on species distributions is critical for marine spatial planning and for modeling energy flows in coastal food webs. The data presented here will aid these endeavors and highlight areas for future research in this important yet understudied system.

Ontogenetic and temporal variability in the fat content and fatty acid composition of Atlantic herring (Clupea harengus) from the Bay of Fundy, Canada

Atlantic herring (Clupea harengus) is an ecologically and economically valuable species in many food webs, yet surprisingly little is known about the variation in the nutritional quality of these fish. Atlantic herring collected from 2005 through 2008 from the Bay of Fundy, Canada, were examined for variability in their nutritional quality by using total lipid content (n=889) and fatty acid composition (n=551) as proxies for nutritional value. A significant positive relationship was found between fish length and total lipid content. Atlantic herring also had significantly different fatty acid signatures by age. Fish from 2005 had significantly lower total lipid content than fish from 2006 through 2008, and all years had significantly different fatty acid signatures. Summer fish were significantly fatter than winter fish and had significantly different fatty acid signatures. For all comparisons (ontogenetic, annual, and seasonal) percent concentrations of omega-3, -6, and long-chain monounsaturated fatty acids were the most important for distinguishing between the fatty acid signatures of fish. This study underscores the importance of quantifying variation in prey quality synoptically with prey quantity in food webs over ontogenetic and temporal scales when evaluating the effect of prey nutritional quality on predators and on modeling trophic dynamics.

Seasonal variability in ichthyoplankton abundance and assemblage composition in the northern Gulf of Mexico off Alabama

Multiyear ichthyoplankton surveys used to monitor larval fish seasonality, abundance, and assemblage structure can provide early indicators of regional ecosystem changes. Numerous ichthyoplankton surveys have been conducted in the northern Gulf of Mexico, but few have had high levels of temporal resolution and sample replication. In this study, ichthyoplankton samples were collected monthly (October 2004–October 2006) at a single station off the coast of Alabama as part of a long-term biological survey. Four seasonal periods were identified from observed and historic water temperatures, including a relatively long (June–October) “summer” period (water temperature >26°C). Fish egg abundance, total larval abundance, and larval taxonomic diversity were significantly related to water temperature (but not salinity), with peaks in the spring, spring–summer, and summer periods, respectively. Larvae collected during the survey represented 58 different families, of which engraulids, sciaenids, carangids, and clupeids were the most prominent. The most abundant taxa collected were unidentified engraulids (50%), sand seatrout (Cynoscion arenarius, 7.5%), Atlantic bumper (Chloroscombrus chrysurus, 5.4%), Atlantic croaker (Micropogonias undulatus, 4.4%), Gulf menhaden (Brevoortia patronus, 3.8%), and unidentified gobiids (3.6%). Larval concentrations for dominant taxa were highly variable between years, but the timing of seasonal occurrence for these taxa was relatively consistent. Documented increases in sea surface temperature on the Alabama shelf may have various implications for larval fish dynamics, as indicated by the presence of tropical larval forms (e.g., fistularids, labrids, scarids, and acanthurids) in our ichthyoplankton collections and in recent juvenile surveys of Alabama and northern Gulf of Mexico seagrass habitats.

Spatial and temporal variability in the relative contribution of king mackerel (Scomberomorus cavalla) stocks to winter mixed fisheries off South Florida

King mackerel (Scomberomorus cavalla) are ecologically and economically important scombrids that inhabit U.S. waters of the Gulf of Mexico (GOM) and Atlantic Ocean (Atlantic). Separate migratory groups, or stocks, migrate from eastern GOM and southeastern U.S. Atlantic to south Florida waters where the stocks mix during winter. Currently, all winter landings from a management-defined south Florida mixing zone are attributed to the GOM stock. In this study, the stock composition of winter landings across three south Florida sampling zones was estimated by using stock-specific otolith morphological variables and Fourier harmonics. The mean accuracies of the jackknifed classifications from stepwise linear discriminant function analysis of otolith shape variables ranged from 66−76% for sex-specific models. Estimates of the contribution of the Atlantic stock to winter landings, derived from maximum likelihood stock mixing models, indicated the contribution was highest off southeastern Florida (as high as 82.8% for females in winter 2001−02) and lowest off southwestern Florida (as low as 14.5% for females in winter 2002−03). Overall, results provided evidence that the Atlantic stock contributes a certain, and perhaps a significant (i.e., ≥50%), percentage of landings taken in the management-defined winter mixing zone off south Florida, and the practice of assigning all winter mixing zone landings to the GOM stock should

Implications of substrate complexity and kelp variability for south-central Alaskan nearshore fish communities

Understanding the interactions between kelp beds and nearshore fish is essential because anthropogenic changes and natural variability in these beds may affect available habitat for fishes. In this study fish communities were investigated in south-central Alaska kelp beds characterized by a range of substrate complexity and varying densities of both perennial understory kelps and annual canopy kelps. Many of the observed fish species, as well as understory and canopy kelps, were positively associated with structurally complex substratum. Targeted canopy and understory kelp beds supported seasonal populations of adult and juvenile Pacific cod (Gadus macrocephalus), rockfishes (Sebastes spp.), and year-round populations of greenlings (Hexagrammos spp.). Monthly changes in kelp and fish communities ref lected seasonal changes; the densities of some species were greatest during periods with higher temperatures. This work illustrates the importance of structurally complex kelp beds with persistent understory kelp populations as important fish habitat for several commercially and recreationally important fishes.

Genetic variability in spotted seatrout (Cynoscion nebulosus), determined with microsatellite DNA markers

Variation in the allele frequencies of five microsatellite loci was surveyed in 1256 individual spotted seatrout (Cynoscion nebulosus) obtained from 12 bays and estuaries from Laguna Madre, Texas, to Charlotte Harbor, Florida, to St. John’s River on the Florida Atlantic Coast. Texas and Louisiana collection sites were resampled each year for two to four years (1998−2001). Genetic differentiation was observed. Spotted seatrout from Florida waters were strongly differentiated from spotted seatrout collected in Louisiana and Texas. The greatest genetic discontinuity was observed between Tampa Bay and Charlotte Harbor, and Charlotte Harbor seatrout were most similar to Atlantic Coast spotted seatrout. Texas and Louisiana samples were not strongly structured within the northwestern Gulf of Mexico and there was little evidence of temporal differentiation within bays. These findings are contrary to those of earlier analyses with allozymes and mitochondrial DNA (mtDNA) where evidence of spatial differentiation was found for spotted seatrout resident on the Texas coast. The differences in genetic structure observed among these markers may reflect differences in response to selective pressure, or may be due to differences in underlying genetic processes.

Impacts of climate change and variability on fish value chains in Uganda

This study examines the vulnerability of fish pr oduction in Uganda, particularly as it r elates to the predicted impacts from climate change, using the concept of the value chain. The value chain approach has been recommended as a useful tool to study specific challenges facing a sector resulting from various drivers of change, including climate. Critically, such analyses can reveal context-specific response strategies to enhance a sector (Jacinto and Pomer oy 2010). The specific purpose of the study was to identify curr ent and potential impacts of climate change and corresponding adaptation strategies in fish value chains. The study builds upon information fr om earlier value chain analyses on fisheries and aquaculture production in Uganda to provide a more in-depth understanding of issues facing the fish industry, in particular, those to be incorporated in the CGIAR Resear ch Program Livestock and Fish.

Variability in supply and cross-shelf transport of pink shrimp (Farfantepenaeus duorarum) postlarvae into western Florida Bay

The variability in the supply of pink shrimp (Farfantepenaeus duorarum) postlarvae and the transport mechanisms of planktonic stages were investigated with field data and simulations of transport. Postlarvae entering the nursery grounds of Florida Bay were collected for three consecutive years at channels that connect the Bay with the Gulf of Mexico, and in channels of the Middle Florida Keys that connect the southeastern margin of the Bay with the Atlantic Ocean. The influx of postlarvae in the Middle Florida Keys was low in magnitude and varied seasonally and among years. In contrast, the greater postlarval influx occurred at the northwestern border of the Bay, where there was a strong seasonal pattern with peaks in influx from July through September each year. Planktonic stages need to travel up to 150 km eastward between spawning grounds (northeast of Dry Tortugas) and nursery grounds (western Florida Bay) in about 30 days, the estimated time of planktonic development for this species. A Lagrangian trajectory model was developed to estimate the drift of planktonic stages across the SW Florida shelf. The model simulated the maximal distance traveled by planktonic stages under various assumptions of behavior. Simulation results indicated that larvae traveling with the instantaneous current and exhibiting a diel behavior travel up to 65 km and 75% of the larvae travel only 30 km. However, the eastward distance traveled increased substantially when a larval response to tides was added to the behavioral variable (distance increased to 200 km and 85% of larvae traveled 150 km). The question is, when during larval development, and where on the shallow SW Florida shelf, does the tidal response become incorporated into the behavior of pink shrimp.