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Data from: Global temperature homogenization can obliterate temporal isolation in migratory animals with potential loss of population structure
No full textClimate change is expected to increase the spatial autocorrelation of temperature, resulting in greater synchronization of climate variables worldwide. Possibly such ?homogenization of the world? leads to elevated risks of extinction and loss of biodiversity. In this study, we develop an empirical example on how increasing synchrony of global temperatures can affect population structure in migratory animals. We studied two subspecies of Bar-tailed Godwits Limosa lapponica breeding in tundra regions in Siberia: yamalensis in the west and taymyrensis further east and north. These subspecies share pre- and post-breeding stopover areas, thus being partially sympatric, but exhibiting temporal segregation. The latter is believed to facilitate reproductive isolation. Using satellite tracking data, we show that migration timing of both subspecies is correlated with the date of snowmelt in their respective breeding sites (later at the taymyrensis breeding range). Snow-cover satellite images demonstrate that the breeding ranges are on different climate trajectories and become more synchronized over time: between 1997 and 2020, the date of snowmelt advanced on average by 0.5 days/year in the taymyrensis breeding range, while it remained stable in the yamalensis breeding range. Previous findings showed how taymyrensis responded to earlier snowmelt by advancing arrival and clutch initiation. In the predicted absence of such advancements in yamalensis, we expect that the two populations will be synchronized by 2036 ? 2040. Since Bar-tailed Godwits are social migrants, this raises the possibility of population exchange and prompts the question whether the two subspecies can maintain their geographic and morphological differences and population-specific migratory routines. The proposed scenario may apply to a wide range of (social) migrants as temporal segregation is crucial for promoting and maintaining reproductive isolation in many (partially sympatric) migratory populations. Homogenization of previously isolated populations could be an important consequence of increasing synchronized environments and hence climate change
SO289 Alkalinity Enhancement Experiment on R/V Sonne.
No full textThis dataset contains 110 measurements of seawater dissolved inorganic carbon (DIC) and total alkalinity (TA) from an alkalinity enhancement expreriment in the South Pacific Ocean. The samples were collected during R/V Sonne cruise SO289 in February-April 2022, as part of the GEOTRACES GP21 research programme to build an understanding of the distribution, origins, and depletions of trace elements and their isotopes (TEIs) in a lesser-explored ocean region. Measurements for TA and DIC were carried out using a VINDTA 3C instrument (#014, Marianda, Germany) and a Seal QuAAtro, gas-segmented continuous flow analyser. All analysis was conducted at the NIOZ Royal Netherlands Institute for Sea Research. Bad results from technical issues during analysis have been removed from these results, so there are no recognised issues. The NIOZ created the metadata entry and is responsible for holding master copies of the data
Vulnerable wildlife concentrations at the Mauritanian Shelf - Atlas of area sensitivity to surface pollutants. NIOZ Report 2022-04
No full textMaritime transport associated with the Grand Tortue Ahmeyim (GTA) gas development project will increase risks for marine wildlife (seabirds and cetaeceans) of the existing threat for accidental spills by international maritime transport, or condensate spills or leakages due to for example ruptures of the wet gas pipeline as a result from fishing activities, accidents, or sabotage.
When an accidental spill occurs, this vulnerability atlas will provide decision makers with easy to digest information on particularly sensitive area, enabling them to see, at a glance, and even before anything happened, when and where sea areas are at risk and where to prioritise clean-up/containment efforts in a crisis situation to protect marine wildlife and fishery resources.
The vulnerability of seabirds to oil (or hydrocarbon) pollution in Mauritania was assessed by parameterising an Oil Vulnerability Index (OVI), used in combination with area specific spatial information on the distribution and density of marine birds (estimates of relative abundance based on state of the art, effort-corrected survey data). The resulting maps predict which areas are most at risk from hydrocarbon spills when they occur.
Traditionally, vulnerability atlases for hydrocarbon pollution are based solely on (sensitive) seabird abundance data, while the presence and abundance of other megafauna is often put aside. Given the global importance of the Mauritanian slope and shelf area, sightings of cetaceans are added as exact plots, to integrate data and to highlight particular biodiversity hotspot areas
A long-term view on recent changes in abundance of common skate complex in the North Sea
No full textFollowing decades of declines, populations of large fish recently started to increase in the North Sea, presumably due to reduced fishing pressure. However, population recovery may be too readily claimed, since standardised sampling of fish stocks commenced only in the 1970s, well after many species had already collapsed. A true recovery must be seen from a long-term perspective. The critically endangered common skate (Dipturus batis, Rajidae) species-complex is an example of a large-bodied fish that mostly disappeared before standardised monitoring took place. Here we put the recent increase in population size into a 120-year perspective, throughout three geographical divisions in the North Sea. We analysed a large range of mostly undisclosed historical data and contemporary sources. A reconstruction of Dutch commercial landings data confirms that the species used to be very abundant between 1902 – 1920, and shows how it steadily declined from 1920 onwards until it got extirpated around 1970. Based on a quantitative analysis of standardized catch numbers from fishery-independent surveys time we conclude that the current abundance of the species is still below historical baselines and represents a local recovery at most. We further demonstrate a prominent and consistent pattern in size-distribution, with larger (mature) individuals only occurring in the northern North Sea. A large dataset on historical stomach contents from the central North Sea confirmed the diet of young common skate, which consisted predominantly of shrimps. Our review exemplifies the importance of marine historical ecology to deduce the natural richness of the North Sea
Seabirds and other charismatic megafauna in offshore habitats off NW Africa : GTA Ecological Vulnerability Analysis. NIOZ Report 2022-03
No full textThis is a compilation of data collected during dedicated, systematic at sea surveys of seabirds and marine mammals: research cruises conducted between 1988 and 2022, mostly off Mauritania (NW Africa). Mauritanian waters are part of the Canary Current Eastern Boundary Upwelling Ecosystem; one of only four such ecosystems in the World (California, Humboldt, Benguela and Canary currents.The resulting database was used to describe their spatio-temporal distribution patterns and relative abundance of charismatic megafauna, characterise their foraging habitats and species interactions, and assess their sensitivity to developments associated with the Greater Tortue Ahmeyim (GTA) gas exploration project.This document gives a first comprehensive, science-based, impression of the megafauna community with emphasis on seabird distribution patterns, seasonal trends, habitats and species interactions in the GTA project area and beyond (West Africa) to help host governments, bp and its partners to improve mitigation management for net-zero impact on biodiversity. The offshore zone harbours internationally important seabird populations, interacting with migrating marine mammals (cetaceans), sea turtles, sharks, other large predatory fish and fishery resources, aggregating in well-defined areas at predictable times. The analysis is focused on ecological guilds, or ?functional groups? of species and on foraging opportunities, thereby to demonstrating the importance of the area within the annual life-cycle of taxa originating from both hemispheres, as a foraging ground during breeding, as a stop-over, or wintering (non-breeding) area
Evaluation of the distributions of hydroxylated isoprenoidal GDGTs in Holocene Baltic Sea sediments for reconstruction of sea surface temperature: The effect of changing salinity
No full textHydroxylated glycerol dibiphytanyl glycerol tetraethers (OH-GDGTs) produced by both marine and freshwater thaumarchaea are increasingly used for the reconstruction of past sea surface temperature (SST). They occur throughout the modern Baltic Sea, but it is unknown if their OH-GDGTs can be used for assessing past SST in this area, where salinity has changed considerably over the Holocene. Three commonly applied OH-GDGT proxies for SST reconstruction, i.e., the OH-GDGT%, RI-OH, and RI-OH? indices, were tested using a Thaumarchaeotal culture enriched from the Baltic Sea grown at 4 and 22?C, and 12 surface sediments from the Baltic Sea and the adjacent Skagerrak. In the culture experiments all three proxies showed the expected response with the rise of temperature, but their absolute values were not always in line with existing marine core top calibrations, especially for the OH-GDGT% index. Of the two proxies based on the distribution of OH-GDGTs, the RI-OH index shows no increase with increasing mean annual SST, whilst the RI-OH? index shows only a linear correlation with SST when the sediments from the Bothnian Sea and Bay area, with a reduced salinity and increased lateral sediment influx, are omitted from the dataset. Two sedimentary Holocene records from the Arkona and Gotland basins were studied, the latter in high resolution. In the brackish phase of the Baltic Sea (the Littorina Sea stage), the RI-OH? index shows a good correlation with the TEX_86^( L), an established temperature proxy in the Baltic Sea, and can be used to identify important climatic events. However, during the preceding Ancylus Lake phase the RI-OH? (and RI-OH) index records far too high values, resulting in anomalously high SST estimates. This is probably because freshwater thaumarchaea adjust their OH-GDGTs differently, as has been shown for thaumarchaea in Lake Lugano?s water column. In the Littorina Sea, the Ancylus Lake and the Yoldia Lake phases of the Baltic basin, the record of the RI-OH? index, thus, most likely reflects both changes in temperature and salinity. Overall, our study indicates that a reduced salinity increases the values of the RI-OH? (and RI-OH) indices substantially and this should be considered when applying these proxies in other settings
Great Skuas and Northern Gannets on Foula, summer 2022 - an unprecedented, H5N1 related massacre
No full textIn summer 2022, a highly pathogenic avian influenza virus (HPAIV) H5N1 pandemic struck, affecting numerous species of colonial seabirds all over the Northern Hemisphere. Great skuas Stercorarius skua and Northern Gannets Morus bassanus were especially badly affected by the outbreak. This report documents the exceptional mortality levels, poor reproductive success and a major population decline in Great Skuas breeding in Foula (Shetland), and a drop in numbers of breeding Northern Gannets on the island. Systematic searches (May-August) produced over 1500 corpses of Great Skuas of which 109 had been ringed earlier in life. The distribution of corpses was non-homogeneous, with clusters of corpses in relatively wet areas, mostly known as clubs and bathing sites. Mortality became apparent in early May, peaked in the second half of May and early June, but continued through the summer at lower levels. In June, Apparently Occupied Territories (AOT) of Great Skuas were counted and it appeared that numbers had declined by 57% since 2015, the most recent earlier survey (from 1820 to 778 AOT). Given the ongoing mortality in July and August, a decline in the order of magnitude of 60-70% in occupied territories is more likely. Great Skuas commenced breeding as usual in May and June, but most attempts failed, mainly because one or both partners got infected and died. The rapid spread of infections over Foula has probably been facilitated by the habit of Great Skuas to bath and socialise at freshwater lochs and pools; sites where close conspecific interactions occur and where all major pathways of infection could play a role: through accumulating of virions in water, aerosols shed from the respiratory tract, via dropped faeces, or by scavenging. How the gannets have picked up the virus is a mystery, but further infections in other marine birds and marine mammals indicate that the virus does cause problems in the marine environment. Gannets bred, but the population declined by 20% during the season (less dramatic than in other Scottish gannetries), while numbers of hatchlings were exceptionally low. Studying the epidemiology and transmission of avian influenza viruses in (pelagic) seabirds in marine habitats is critical to understand how and where outbreaks develop and spread
Disentangling the diet composition of Arctic shorebirds? chicks provides a new perspective on trophic mismatches: dataset
No full textWe use metabarcoding of prey items in faeces to show that chicks of four different shorebird species (red knot, curlew sandpiper, little stint, and red phalarope) strongly differ in their arthropod diet, which may have implications for the calculations of trophic mismatches
Food web interactions of breeding Arctic shorebirds are shaped by their elevational distribution: dataset
No full textWe describe the spatial position of little stints and red knots in the tundra food web, from both a top-down and a bottom-up perspective, and suggest that these affect shorebird diet and survival. The availability of the key food items for chicks is related to their diet, and, although it is not possible to fully disentangle cause and effect, we find support that the diet differences are explained by elevation. Moreover, the difference in the elevational distribution of shorebird nests impacts their relationships with predators
ADCP data Whittard Canyon 64PE453-53
No full textThis dataset covers ADCP data collected in Whittard Canyon at 2200 m water depth. THe 75 kHz ADCP was upward looking and deployed in Whittard to monitor daily to seasonal changes in current speed and acoustic backscatter.
Challenging the highstand-dormant paradigm for land-detached submarine canyons (Heijnen et al.):
Abstract: Sediment, nutrients, organic carbon and pollutants are funnelled down submarine canyons from continental shelves by sediment-laden flows called turbidity currents, which dominate particulate transfer to the deep sea. Post-glacial sea-level rise disconnected more than three quarters of the >9000 submarine canyons worldwide from their former river or long-shore drift sediment inputs. Existing models therefore assume that land-detached submarine canyons are dormant in the present-day; however, monitoring has focused on land-attached canyons and this paradigm remains untested. Here we present the most detailed field measurements yet of turbidity currents within a land-detached submarine canyon, documenting a remarkably similar frequency (6 yr-1) and speed (up to 5-8 ms-1) to those in large land-attached submarine canyons. Major triggers such as storms or earthquakes are not required; instead, seasonal variations in cross-shelf sediment transport explain temporal-clustering of flows, and why the storm season is surprisingly absent of turbidity currents. As >1000 other canyons have a similar configuration, we propose that contemporary deep-sea particulate transport via such land- detached canyons may have been dramatically under-estimated