The new Arctic in the global context - Ecosystem Part 1
- 09:10 FEATURED TALK: Sea-ice phenology in a warmer Arctic
Authors: Letizia Tedesco ( Finnish Environment Institute ); Marcello Vichi ( University of Cape Town ); Enrico Scoccimarro ( Euro-Mediterranean Center on Climate Change )
Future projections of Arctic sea-ice changes are alarming, but the response of the ice-associated biological community is still uncertain. Here we investigate future changes in timing and intensity of primary production in Arctic first-year ice using a combination of climate and sea-ice biogeochemistry models. Overall, model results suggest a general increase in sea-ice primary production at all latitudes during this century. However, the projected phenological changes are not as quasi-monotonic as the changes in physical drivers. Three latitudinal clusters are identified and distinctly explained by snow cover thinning at the lowest latitudes, biological time windows narrowing in the mid latitudes, and ice seasons advancing towards more favourable photoperiods at the highest latitudes. When considering the changes in ice extent, the increase in sea-ice production at the highest latitudes is boosted due to significant first-year ice expansion at the expense of multiyear ice. The projected changes in sea-ice primary production suggest potential far-reaching consequences for the whole Arctic marine food web.
- 09:40 Mesopelagic layers in the European Arctic: seasonal migrations and trophic interactions.
Authors: Maxime Geoffroy ( Fisheries and Marine Institute of Memorial University of Newfoundland ); Malin Daase ( UiT ); Jørgen Berge ( UiT ); Martin Graeve ( AWI ); Marine Cusa ( UiT ); Nestor Hernandez ( UiT ); Stig Falk-Petersen ( APN )
A mesopelagic sound scattering layer (SSL) was detected with a multifrequency echosounder in the European sector of the Arctic Ocean, both during the polar night and the midnight sun periods. The SSL was located within Atlantic water masses, and pelagic trawling suggested that it was mainly composed of age-0 fish (mainly Sebastes mentella and Leptoclinus maculatus) as well as macrozooplankton (mainly Cyanea capillata, Themisto libellula, Meganyctiphanes norvegica and Thysanoessa inermis). Most abundant species were analysed for total lipids and fatty acid trophic markers. We present data on the total available energy expressed as lipids available for higher trophic animals in these mesopelagic layers. By combining new data on fatty acid trophic markers with published data, we are presenting a new approach to describe the energy transfer from phytoplankton and ice algae to apex predators. We suggest that the prevalence of a high-energy SSL when the ice edge retracts northwards might explain the large Dutch bowhead whaling that took place in Whalers Bay between 1670 to 1800, as well as recent observations of whale aggregations. This study is a part of the RCN funded Arctic ABC project (http://www.mare-incognitum.no/) and of the Arctic Size project at UiT The Arctic University of Norway.
- 09:55 The AmP project : a Framework for integrating Eco-physiological data into marine ecosystem-based management tools
Authors: Starrlight Augustine ( Akvaplan-niva ); Konstadia Lika ( University of Crete ); Laure Pecquerie ( IRD ); Goncalo M. Marques ( Instituto Superior Técnico ); Sebastiaan A. L. M. Kooijman ( VU University )
The role of biodiversity in ecosystem structure and functioning is crucial for conservation and environmental quality management, as well as biospheric and system earth studies. Scientists are turning towards trait based approaches to tackle this issue by investigating for example which traits make a particular species invasive, or else make it resistant (or sensitive) to pollution or climate change, which traits co-exist under what circumstances...
We present in this talk a rigorous trait based approach that aims to: (i) find the simplest organisation principles for metabolism upon which all life is based and (ii) understand taxon-specific patterns as variations on this common theme. This approach is the AmP project: 'Add-my-Pet' database of Dynamic Energy Budget (DEB) models, parameters and referenced underlying data for animals. AmP started in 2009 and, to date, 120 authors submitted entries to the collection. In the context of the NFR project "Framework for integrating Eco-physiological and Ecotoxicological data into marine ecosystem-based management tools" we included many new arctic species like snow crab, shrimps. Auks, reindeer, seals, whales, Greenland shark etc.
The DEB models proved to fit data well, the mean relative error is less than 0.1, for 785 animal species at 2017/09/06, including some extinct ones, from all large phyla and all chordate orders, spanning a range of body masses of 16 orders of magnitude. Each DEB parameter has a clear link with one underlying physiological process and the combination of parameters covers all aspects of energetics throughout the full life cycle of organisms, from the start of embryo development to death by aging. These aspects include feeding, digestion, storage, maintenance, growth, development, reproduction, aging.
DEB models apply to all life on earth and allow us to compare species on the basis of (functions of) parameters of that model. AmP comprises the methodology and code that allows estimating the parameters for any animal species. This talk presents the rapidly extending AmP collection on the web, presents new code that analyses patterns in parameter values of species and discusses the application of AmP as a framework for integrating eco-physiological data into ecosystem-based management in the Arctic.
- 10:10 The importance of giants in a world of dwarfs
Authors: Pedro Duarte ( Norwegian Polar Institute ); Andrew Lowther ( Norwegian Polar Institute ); Philipp Assmy ( Norwegian Polar Institute ); Geir Gabrielsen ( Norwegian Polar Institute ); Kit Kovacs ( Norwegian Polar Institute ); Christian Lydersen ( Norwegian Polar Institute ); Gary Griffith ( Norwegian Polar Institute )
The main goal of this study was to explore the importance of higher trophic levels (HTL) in Arctic marine ecosystems functioning. Hereafter, HTL are defined as organisms in or above the fourth trophic level. Notwithstanding the fundamental importance of these organisms as a food source for the Arctic societies, their cultural and aesthetic values (and tourist appeal), their role in biogeochemical processes and top-down control within Arctic marine ecosystems is yet to be quantified. What will happen if these organisms decrease in abundance or are replaced by their temperate equivalents? We are seeing evidence of declines and substitutions in several bird and fish species in the Svalbard Archipelago. We argue that there is a deficiency in the scientific debate of this question in the Arctic in comparison with the Southern Ocean, where the role of HTL has been discussed in connection with iron recycling for primary production and the decline in krill populations. HTL organisms have an important role in the exchange of nutrients between terrestrial and marine environments, from deep sea to surface waters and from nutrient hotspots to oligotrophic areas. These species may also exert a significant top-down effect on prey populations, thus shaping the ecosystem. Importantly, the long life span of some of these organisms makes them a nutrient buffer, dampening the loss of nutrients to the deep ocean through the typical boom and bust cycles of the Arctic phytoplankton and ice algal blooms. Instead, HTL species keep nutrients available at the surface, where they are partially released through fast recycling excretion pathways that may be used readily for regenerated production. Birds and mammals are thought to consume up to 13% of the net primary production in Kongsfjorden, Svalbard, which suggests that they play an important role in coastal ecosystem functioning. It is likely that this role decreases from coastal to open ocean environments. Current ecosystem models show a dichotomy between lower and HTL based approaches, reflecting difficulties in coupling processes at spatial and temporal scales that span over several orders of magnitude. This dichotomy limits our capacity to evaluate bottom-up and top-down ecosystem effects and their biogeochemical feedbacks. We discuss the need and the methods to overcome these limitations in a context of climate-induced ecosystem restructuring.
- 10:25 Small-scale spatial patterns of soil organic carbon and macro-nutrients in northern Siberian permafrost-affected soils
Authors: Alevtina Evgrafova ( University of Bern/University of Koblenz-Landau ); Tilman de la Haye ( University of Bern ); Ina Haase ( Leibniz University of Hannover ); Olga Shibistova ( Leibniz University of Hannover/VN Sukachev Institute of Forest ); Georg Guggenberger ( Leibniz University of Hannover/VN Sukachev Institute of Forest ); Nikita Tananaev ( Igarka Geocryology Laboratory, Melnikov Permafrost Institute SB RAS ); Leopold Sauheitl ( Leibniz University of Hannover ); Sandra Spielvogel ( University of Bern/University of Kiel )
Thawing permafrost, driven by climate change, alters pedogenic processes and properties as well as soil-plant-atmosphere interactions in high-latitude regions. Increased plant-available macronutrients, i.e. nitrogen (N) and phosphorus (P), may induce vegetation growth and further vegetation community shifts in polar climate regions. However, the influence of permafrost thaw on the spatial distribution and variability of permafrost-affected soil properties remains unclear.
This research studied the changes in spatial patterns and relationships between soil organic carbon (SOC), N and P stocks (0-30 cm) and active layer thickness (ALT), soil acidity, pedogenic (hydr)oxides, and plant-derived C inputs and neutral sugars as a result of permafrost degradation within the six study grids (16 m2) using the principles of geostatistics. The study grids, characterized by various ALT and under different vegetation communities, were located within the forest-tundra ecotone underlain by warm and discontinuous permafrost at the Little Graviyka Creek catchment (67°28.933’N, 86°25.682’E). The soil samples were collected from two depth increments, top- (n=61) and subsoil (n=61) for each study grid, with a sample spacing of 0.2, 0.5 and 1.0 meters.
The results showed that permafrost thaw caused a decrease and homogenization of SOC, N and P stocks and increase in P availability for plants within the studied small-scale grids. Moreover, declining permafrost table led to the formation of soil organic matter (SOM) accumulation “hot spots” in thawed soil horizons, associated with the development of organo-mineral associations and deeper root systems. The semivariogram ranges for SOC and N stocks were estimated at less than 3.1 m. The nugget-to-sill ratios were estimated between 29 and 52% for shallow AL soils and between 19 and 34% for intermediate AL and non-permafrost soils. Based on vegetation analyses, higher grid-specific vascular species abundance was observed for grids with a deeper ALT likely due to the increased availability of macronutrients, while species diversity was lower likely due to more homogeneous distribution of macronutrients. Hence, the changes in vegetation communities in high-latitude regions could be an indicator of permafrost thawing linked to possible vegetation shifts and changing carbon sequestration potential in the Arctic regions. Combined research on vegetation structure and ecosystem carbon storage capacity can be seen as a key approach for estimating carbon and biodiversity losses driven by permafrost degradation.
Wednesday 24th January 2018
09:10 - 10:40