8604 research outputs found
Sort by
Influence of open ocean biogeochemistry on aerosol and clouds: Recent findings and perspectives
Get PDFAerosols and clouds are key components of the marine atmosphere, impacting the Earth’s radiative budget with a net cooling effect over the industrial era that counterbalances greenhouse gas warming, yet with an uncertain amplitude. Here we report recent advances in our understanding of how open ocean aerosol sources are modulated by ocean biogeochemistry and how they, in turn, shape cloud coverage and properties. We
organize these findings in successive steps from ocean biogeochemical processes to particle formation by nucleation and sea spray emissions, further particle growth by condensation of gases, the potential to act as cloud condensation nuclei or ice nucleating particles, and finally, their effects on cloud formation, optical properties, and life cycle. We discuss how these processes may be impacted in a warming climate and the potential for ocean biogeochemistry—climate feedbacks through aerosols and clouds
Detrital Input Sustains Diatom Production off a Glaciated Arctic Coast
Get PDFIn the Arctic and subarctic oceans, the relatively low supply of silicon (compared to othernutrients) can make it limiting for the growth of diatoms, a fundamental building block of the oceanic food web. Glaciers release large quantities of dissolved silicon and dissolvable solid amorphous silica phases into high‐latitude estuaries (fjords), but the role of these glacially‐derived silica phases in sustaining diatom growth in the coastal and open‐water sectors remains unknown. Here we show how stable and radiogenic silicon isotopes canbe used together to address this question, using southwest Greenland as a case study. This study finds enhanced levels of detrital (i.e., mineral) amorphous silica, likely glacially‐sourced, sustaining a large portion of diatomgrowth observed off the coast, revealing how the phytoplankton community can function during high-meltwater periods
Recent trends and biases in mesophotic ecosystem research
No full textMesophotic ecosystems (approx. 30–150 m) represent a significant proportion of the world’s oceans yet have long remained understudied due to challenges in accessing these deeper depths. Owing to advances in underwater technologies and a growing scientific and management interest, there has been a major expansion in research of both (sub)tropical mesophotic coral ecosystems and temperate mesophotic ecosystems. Here, we characterize the recent global trends in mesophotic research through an updated release of the ‘mesophotic.org’ database (www.mesophotic.org) where we reviewed and catalogued 1500 scientific publications. In doing so, we shed light on four major research biases: a gross imbalance in (a) the geographical spread of research efforts, differences in (b) the focal depth range and (c) research fields associated with study organisms and research platforms, and (d) the lack of temporal studies. Overall, we are optimistic about the future of mesophotic research and hope that by highlighting current trends and imbalances, we can raise awareness and stimulate discussion on the future directions of this emerging fiel
Electron microscopy characterization of king scallop (Pecten maximus) shells from low-voltage SEM to 3D-EBSD reconstruction
No full textThe shell of the bivalve Pecten maximus, also called the king scallop, was previously found to be detrimentally affected by the presence of metal contamination, in particular Cu, Pb, and Zn originating from mining activities on the Isle of Man [1]. In addition to a reduction of shell thickness, scallop shells from the contaminated area exhibit a sharp break line in the mineralization within the foliated region of both the top and bottom valves. Our data suggest that these mineralization break line caused reduced fracture strength compared to pollution�free scallops, which results in increased mortality due to predation and during the process of dredging. These break lines have already been referred to as being of aragonitic prismatic structure [2].
To shed light on the possible impact of metal contaminations on the growth and strength of scallop shells and in particular on the 3D morphology and microstructure of the scallop, from contaminated and uncontaminated sites, we used characterization tools at different length scales (from cm to µm) using electron and X-ray probes to determine areas of interest in contaminated and healthy (uncontaminated) shells to finally realize crystallographic orientation map using EBSD technique and localized 3D reconstruction by focused ion beam techniques (FIB). The aim of this study was to combine these techniques to produce a full 3D EBSD map of the crystallographic orientations of the critical zone
7th Conference of Advances in Marine Ecosystem Modelling Research - Conference Proceedings and Book of Abstracts
Get PDFThe AMEMR (Advances in Marine Ecosystem Modelling Research) Symposium series provides an opportunity to present, discuss and learn about a wide variety of marine modelling challenges, methods, applications and outcomes. Held approximately every three years and now in its 7th iteration, AMEMR has grown into the forum to present and absorb the latest developments in marine (eco)system modelling and discuss new challenges and opportunities. Modelling is a fundamental tool for understanding marine ecosystems and providing projections of potential future states of the environment. Marine modelling is continuously evolving, in response to new scientific knowledge, techniques and societal needs. AMEMR promotes interdisciplinary discussion among stakeholders and modelling, observational and experimental scientists and students who want to contribute to the conceptualisation, design, development and application of improved and new marine ecosystem models of all types. We emphasize networking, discussion and encourage a strong ECR involvement
Long‐term shifts in phenology, thermal niche, population size, and their interactions in marine pelagic copepods
Get PDFUnder climatic warming many species shift their seasonal timing of life cycle events (phenology) and sea�sonal abundance distribution, but whether they maintain the same thermal niche is still poorly understood.
Here, we studied multidecadal trends in abundance and phenology of seven major copepod species across three
stations (Stonehaven (SH), Helgoland Roads (HR), and Plymouth L4) on the North–West European shelf, span�ning � 6.5� of latitude. All seven species consistently occupied colder temperatures at the northern station com�pared to the southerly station, but they maintained the same realized thermal niche over years. Expected
phenological shifts (i.e., earlier when warmer) in some stations were obscured possibly by the long-term drop of
copepod density in spring–summer, which may be due to a variation in the food/predators abundance. The
ongoing spring–summer declines in abundance (� 50%) of many North Atlantic pelagic species over the last five
decades, as found in recent studies, may have also influenced the metrics of seasonal timing. To separate the
seasonal timing of life events from that of seasonal abundance distribution, we used a time series of egg produc�tion rate (EPR) of Calanus helgolandicus at L4, and found that this shifted later into the summer–autumn over
the last 30 yr of warming, coincident with declining spring–summer food and increasing predator abundance.
Overall, direct temperature effects do appear to influence the seasonal timing of the copepods, but to explain
impacts at individual stations or long-term trends in population size or phenology, understanding the changing
balance of food and predators appears to be critica
Investigating ecosystem connections in the shelf sea environment using complex networks
Get PDFWe use complex network theory to better represent and understand the ecosystem connectivity in a shelf sea
environment. The baseline data used for the analysis are
obtained from a state-of-the-art coupled marine physics–
biogeochemistry model simulating the North West European
Shelf (NWES). The complex network built on model outputs is used to identify the functional groups of variables behind the biogeochemistry dynamics, suggesting how to simplify our understanding of the complex web of interactions within the shelf sea ecosystem. We demonstrate that complex networks can also be used to understand spatial ecosystem connectivity, identifying both the (geographically varying) connectivity length-scales and the clusters of spatial locations that are connected. We show that the biogeochemical length-scales vary significantly between variables and are not directly transferable. We also find that the spatial pat�tern of length-scales is similar across each variable, as long
as a specific scaling factor for each variable is taken into
account. The clusters indicate geographical regions within
which there is a large exchange of information within the
ecosystem, while information exchange across the boundaries between these regions is limited. The results of this
study describe how information is expected to propagate
through the shelf sea ecosystem, and how it can be used in
multiple future applications such as stochastic noise modelling, data assimilation, or machine learnin
Incorporating climate-readiness into fisheries management strategies
Get PDFTropical oceans are among the first places to exhibit climate change signals, affecting the habitat distribution and abundance of marine fish. These changes to stocks, and subsequent impacts on fisheries production, may have considerable implications for coastal communities dependent on fisheries for food security and livelihoods. Understanding the impacts of climate change on tropical marine fisheries is therefore an important step towards developing sustainable, climate-ready fisheries management measures. We apply an established method of spatial meta-analysis to assess species distribution modelling datasets for key species targeted by the Philippines capture fisheries. We analysed datasets under two global emissions scenarios (RCP4.5 and RCP8.5) and varying degrees of fishing pressure to quantify potential climate vulnerability of the target community. We found widespread responses to climate change in pelagic species in particular, with abundances projected to decline across much of the case study area, highlighting the challenges of maintaining food security in the face of a rapidly changing climate. We argue that sustainable fisheries management in the Philippines in the face of climate change can only be achieved through management strategies that allow for the mitigation of, and adaptation to, pressures already locked into the climate system for the near term. Our analysis may support this, providing fisheries managers with the means to identify potential climate change hotspots, bright spots and refugia, thereby supporting the development of climate-ready management plans
Range extension of invasive Cancer irroratus and native Carcinus maenas polewards in the Ascophyllum-dominated intertidal zone in north-west Iceland
No full textThe rocky intertidal zone of sheltered shores in Breiðafjörður, north-west Iceland is dominated by monospecific stands of canopy-forming brown algae Ascophyllum nodosum, which provide habitat for mobile organisms and has been subjected to long-standing rotational harvesting. We investigated the assemblage composition of little-studied mobile brachyuran crabs in this area, to track distributional shifts in a native species responding to climate change and extent of occupancy of the intertidal by a primarily subtidal invasive non-native species. Potential interactive effects of seaweed harvesting were explored. Breiðafjörður was compared with two reference sites in Faxaflói, south-west Iceland. The study revealed clear poleward expansion of the native European green crab Carcinus maenas in the region, displacing the native spider crab Hyas araneus particularly at mid-shore levels. The invasive non-native Atlantic rock crab Cancer irroratus had negligible occupancy in the intertidal zone, indicating limited effects on the intertidal crab assemblage, composition, and abundance. The current harvesting regime of A. nodosum in Breiðafjörður did not affect the composition and abundance of the brachyuran crab assemblage in the rocky intertidal zone. H. araneus is likely being squeezed by displacement subtidally by C. irroratus, and intertidally by C. maenas. Overall, we provide insights into the potential interactions between climate change, invasive species, and human activities in the rocky intertidal zone
Quantifying decadal stability of lake reflectance and chlorophyll-a from medium-resolution ocean color sensors
Get PDFMulti-decadal time-series of Lake Water-Leaving Reflectance (LWLR), part of the Lakes Essential Climate Variable, have typically been interrupted for the 2012–2016 period due to lack of an ocean color sensor with ca�pabilities equivalent to MERIS (2002− 2012) and OLCI (2016 - present). Here we assess, for the first time, the suitability of MODIS/Aqua to estimate LWLR and the derived concentration of chlorophyll-a (Chla) at the global
scale across optically complex water types, in an effort to fill these information gaps for climate studies. We first
compare the normalized water-leaving reflectance (Rw) derived from two atmospheric correction algorithms (POLYMER and L2gen) against in situ observations. POLYMER shows superior performance, considering the agreement with in situ measurements and the number of valid outputs. An extensive assessment of nine Chla algorithms is then performed on POLYMER-corrected Rw from MODIS observations. The algorithms are tested both in original parameterizations and following calibration against in situ measurements of Chla. We find that
the performance of algorithms parameterized per Optical Water Type (OWT) allows considerable improvement of the global Chla retrieval capability. Using 3 years of overlapping observations between MODIS/Aqua and MERIS (2009–2011) and OLCI (2017–2019), respectively, MODIS-derived reflectance and Chla products showed a reasonable degree of long-term stability in 48 inland water bodies. These water bodies, therefore, mark the candidates to study long-term environmental change