Fish and epibenthic assemblages in the Chukchi Sea
Fish and epibenthic assemblages in the Chukchi Sea: observations and predictions BA Bluhm, BL Norcross, K Iken, F Huettmann, BA Holladay (all University of Alaska Fairbanks), BI Sirenko (Zoological Institute RAS)
Demersal fish and epifauna • Plumb-staff beam trawl, 7 mm mesh (4 mm in cod end) • 2 -5 min hauls on bottom • Sort, count, weight, identify • 2004 -2009, 165 fish st, 42 epifauna st
Why care? • Climate signal integrators • Prey for subsistence species • Species of potential subsistence and commercial fisheries (snow crab) • Contribution to carbon cycling • Commitment to Circumpolar Biodiversity Monitoring Program (Arctic Council)
Fish Faunal similarity Central North Coastal Northeast Transform: Square root Resemblance: S 17 Bray Curtis similarity Fish-Epifauna 2 D Stress: 0. 22 Central east Herald Valley Southwest Coastal d h i j c f e g b a Similarity East Siberian Sea 30
Observed fish assemblages Wrangel Isl. Herald Canyon East Siberian Sea Icy Cape Alaska Chukotka Clustering based on fish biomass, square-root transformed, Bray-Curtis similarity
Characteristic species Wrangel Isl. Herald Canyon East Siberian Sea Icy Cape Alaska Chukotka Taxa contributing ≥ 10% to within cluster similarity
Observed fish-epifauna assemblages Point Hope Kotzebue Sound Bering Strait Clustering based on fish and epifauna biomass, square-root transformed, Bray-Curtis similarity
Characteristic species Point Hope Kotzebue Sound Bering Strait Taxa contributing ≥ 10% to within cluster similarity (fish species contributed ≤ 7%) Mean fish biomass per cluster 2 -10% of total haul biomass
Environmental variables considered Variable Unit Distance to mean Meters summer ice edge Bottom temperature ºC Integrated chlorophyll a concentration Mg chl a/m 2 Water depth Meters Grain size % phi 5 (silt) Sea surface Temp. ºC (10 m) Bottom salinity PSU Source Variable Unit Aspect Degrees Distance to run- Meters Compiled by S. Okkonen off (Univ. of Alaska Slope Degrees Fairbanks) for Pac. MARS project Distance to coast Meters Matrai et al. , integrated Sea surface by C. Ashjian (WHOI) PSU salinity for Pac. MARS U. S. National Ice Center IBCAO J. Grebmeier, U Maryland, compiled for Pac. MARS World Ocean Atlas Compiled by S. Okkonen (UAF) for Pac. MARS Silicate conc. Phosphate concentration Apparent O 2 utilization Source IBCAO R-Arctic. Net IBCAO Worldcoastline webportal World Ocean Atlas Mmol/m 3 World Ocean Atlas Mol O 2/m 3 World Ocean Atlas
East Siberian Sea Wrangel Isl. Herald Canyon Icy Cape Alaska Chukotka Predicted assemblages northeast central Bathymetry (m) 0 - 25 26 - 50 tal 51 - 75 s c oa 76 - 150 151 - 1000 1001 - 4000 Bering Sea
north central northeast l sta coa Environmental niches for fish assemblages North: near mean summer sea ice extent, low bottom temperature Central : high chlorophyll a, near ice edge, muddy sediment, >40 m Northeast: coarse sediment, <40 m, high(er) bottom temperature, rel. low chlorophyll Coastal: near coast, high surface and bottom temperatures, far from ice edge
Thanks! • Funding through RUSALCA (NOAACIFAR), PEW Environmental Group (US Arctic Program), CMI (Fish), • Species identifications aided by Drs L Cole, K Coyle, D Fautin, A Gebruk, M Hoberg, P Kuklinski, C Mah, CW Mecklenburg, E Rodriguez, A Rogaecheva, I Smirnov, O Tendal • Vessel support, Ship crews and trawl teams of Prof. Khromov, Oscar Dyson /AFSC/NOAA, Oshoru Maru / Hokkaido Univ.
Temporal comparison of epifauna and food web in the southern Chukchi Sea (2004, 2009, 2012): First results BA Bluhm, KB Iken, C Serratos (all University of Alaska Fairbanks), B Sirenko (Zoological Institute RAS)
Why care? Epifauna • Climate signal integrators (long-lived) • Prey for subsistence species • Species of potential subsistence and commercial fisheries (snow crab) • Contribution to carbon cycling • Commitment to Circumpolar Biodiversity Monitoring Program (Arctic Council) Food web • Carbon flow • Food web length – carbon transfer efficiency • Pelagic-benthic coupling • • • Plumb-staff beam trawl, 7 mm mesh (4 mm in cod end) 2 -5 min hauls on bottom Sort, count, weight, identify
Time series stations BSW AW ACW Freshwater inflow, gravel Chukchi Sea A B D C E G F Hard substrate Bering Sea
Biomass and composition A Russian coast B C G Anadyr Water D Bering Shelf Water E F Alaskan coast Caveat: No replicate trawl hauls
Biomass trend
Snow crab: abundant but small in Chukchi Mean 40 SD 11 N=2669 Mean 69 SD 29 N=344
Community structure stable Russian coast Anadyr Water Point Hope Coastal Current
Food web – trophic levels 2009 2004 18 ØAW consumers depleted in δ 15 N compared to ACW in both years ØUse of fresher (=isotopically light) material through shorter food chains in AW 16 δ 15 N 14 12 10 8 2012 6 4 AW ACW POM Surface deposit - bivalves Strongylocentrotus droebach. Neptunea sp. Leptasterias sp. Nephtys sp. Pagurus rathbuni Hyas coarctatus Chionoecetes opilio Argis lar Gymnocanthus tricuspis Myoxocephalus scorpius Lumpenus fabricii Boreogadus saida
Food web – carbon source 2009 2004 -14 ØConsumer δ 13 C depleted in ACW – possible freshwater signal -15 -16 ØDepleted δ 13 C POM in AW in 2009 – strong freshwater signal in 2009 -17 δ 13 C -18 -19 -20 2012 -21 -22 -23 -24 -25 AW ACW AW 2004 results: Iken K et al (2010) Deep-Sea Research II 57: 71 - ACW POM Surface deposit - bivalves Strongylocentrotus droebach. Neptunea sp. Leptasterias sp. Nephtys sp. Pagurus rathbuni Hyas coarctatus Chionoecetes opilio Argis lar Gymnocanthus tricuspis Myoxocephalus scorpius Lumpenus fabricii Boreogadus saida
Learned so far? Epifauna • Biomass variable between years • Individual species can drive tends (stock fluctuations in snow crab? • Community structure stable in area, different by substrate and water mass Food web • Food web reflects water masses (tight pelagicbenthic coupling in AW) • Food web structure stable between 2004 and 2009 • Food source signal variable at point measurement • Combination of metrics tell more than one metric
Thanks! • Funding through NOAA-CIFAR NA 08 OAR 4320870, CIFAR IPY • Ship crews and trawl team of Prof. Khromov, B. Holladay • Crab funding (CMI, BOEM), and lab team • Stable isotope lab team • Species identifications aided by Drs L Cole, K Coyle, D Fautin, A Gebruk, M Hoberg, P Kuklinski, C Mah, CW Mecklenburg, E Rodriguez, A Rogaecheva, I Smirnov, O Tendal
RUSALCA Synthesis - Bio: Have • Species distributions • Community distributions • Biomass / abundance distributions • Food web • Some fluxes • Some rates (benthic respiration, copepod egg production) • Variability / change over time (to varying degrees) Need from phys-chem-geo • Spatial and temporal patterns of environmental conditions on different scales (next slide) for water column and (near) bottom (latitude / longitude, depth, value) • Joint interpretation! • Mapping support across projects for special issue?
Life cycles provide integration scales Bacteria larvae µm Day month zooplankton fishes benthos mm cm dm year decade mammals m century
Possible papers • One overarching highlights paper (or extended editorial to special issue) • Regional highlight, system description as multi-year composite: Herald Canyon area • Temporal variability highlight: focus on DBO 3 • All multidisciplinary, multi-author, multinational • Unique and complementary to other synthesis efforts • Need lead team (Russia/USA) or interdisciplinary postdoc based in both countries (Liza-Maria concept)
RUSALCA Synthesis - Bio Future Need next decade? • Continue time series (minimum DBO transect 3? ) • Increased integration with phys-chem-geo • More rates: Current rates, e. g. grazing, growth, age • Future rates through experiments? • Thermal windows and physiological plasticity? • Link to sea ice? • Predictive capability? • Carbon flux model? • Interdisciplinary post-docs with Russia-US advisory team, based in two countries?
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