scholarly journals Commercial fish abundance estimation in the Belgian part of the North Sea through eDNA ddPCR analyses

2021 ◽  
Vol 4 ◽  
Author(s):  
Sam Desmet ◽  
Rein Brys ◽  
Sabrina Neyrinck ◽  
Kris Hostens ◽  
Sofie Derycke
Keyword(s):  
Community Composition ◽  
North Sea ◽  
Water Samples ◽  
Fish Abundance ◽  
Small Scale ◽  
Target Species ◽  
Important Species ◽  
The North ◽  
Marine Diversity ◽  
The North Sea

Monitoring of fish assemblages in the Belgian part of the North Sea (BPNS) mainly happens through trawling. While effective, this method is invasive and destructive as it disturbs bottom communities, catches non-target species and removes organisms from the environment. A more sustainable alternative for monitoring marine diversity is the use of environmental DNA (eDNA) which comprises intra- and extracellular genetic material that comes from the shedding of organic material, like scales and mucus in the case of fish. When applying metabarcoding on eDNA, community composition can be inferred simply by analysing a small volume of water. Therefore the technique does not disturb the environment, and the high sensitivity of eDNA allows the detection of rare and transient species that are frequently missed by traditional sampling methods. Next to determining community composition, the amount of eDNA copies in the water could potentially be used to quantify target fish species in the marine environment. Here, we investigate whether eDNA concentrations from marine water samples correlate with local fish abundance estimates obtained via traditional beam trawling. Species specific Droplet Digital Polymerase Chain Reaction (ddPCR) assays were designed and tested for three economically important species: common sole (Solea solea), plaice (Pleuronectes platessa) and whiting (Merlangius merlangus). In march 2020, 12 sites in the BPNS were selected based on absence, low and high abundances of the three target species as observed in epibenthos monitoring data from previous years. In each site, 2L of seawater was collected with a niskin bottle from ca 1m above the sea floor. Subsequently, beam trawl transects of 1 km were conducted and all epibenthos species caught in the trawling net were morphologically identified, counted and weighted. Our results indicate promising correlations between eDNA concentrations obtained with the ddPCR assays and the number of specimens in the net for all three species. Some “false” positive results were obtained with the ddPCR, but these may actually be “true” positive detections because the fish might be present in the area but were not caught in the trawling transects. This warrants further investigation to see how far eDNA signals can be detected in the North Sea system. Next, 50 water samples were collected in Autumn 2020, involving more locations with or without the three fishes. This time samples were taken at the beginning, middle and end of the 1 km transects to investigate small scale horizontal variation in eDNA concentrations. The autumn samples are currently being processed. In March 2021, samples will be taken at different depths (surface, middle of the water column and ca 1m above the seafloor) to investigate whether there are any vertical patterns in eDNA distribution in a very well mixed system such as the BPNS. A DNA shedding experiment will be performed as well to estimate the rate at which the three fishes shed DNA. This will provide important information on how quickly fishes can be detected when they swim by. The information obtained with the field sampling and experimental setting will help to strengthen the correlation to a point that reliable abundance estimations of our target species become possible and will allow us to evaluate the potential of eDNA as a sustainable alternative/addition to traditional monitoring methods.

scholarly journals Forage fish, their fisheries, and their predators: who drives whom?

2013 ◽  
Vol 71 (1) ◽  
pp. 90-104 ◽  
Author(s):  
Georg H. Engelhard ◽  
Myron A. Peck ◽  
Anna Rindorf ◽  
Sophie C. Smout ◽  
Mikael van Deurs ◽  
...  
Keyword(s):  
North Sea ◽  
Strong Interactions ◽  
Small Scale ◽  
Forage Fish ◽  
Human Consumption ◽  
Important Species ◽  
Piscivorous Fish ◽  
The North ◽  
The North Sea ◽  
The Impact

Abstract Engelhard, G. H., Peck, M. A., Rindorf, A., Smout, S. C., van Deurs, M., Raab, K., Andersen, K. H., Garthe, S., Lauerburg, R. A. M., Scott, F., Brunel, T., Aarts, G., van Kooten, T., and Dickey-Collas, M. Forage fish, their fisheries, and their predators: who drives whom? – ICES Journal of Marine Science, 71: . The North Sea has a diverse forage fish assemblage, including herring, targeted for human consumption; sandeel, sprat, and Norway pout, exploited by industrial fisheries; and some sardine and anchovy, supporting small-scale fisheries. All show large abundance fluctuations, impacting on fisheries and predators. We review field, laboratory, and modelling studies to investigate the drivers of this complex system of forage fish. Climate clearly influences forage fish productivity; however, any single-species considerations of the influence of climate might fail if strong interactions between forage fish exist, as in the North Sea. Sandeel appears to be the most important prey forage fish. Seabirds are most dependent on forage fish, due to specialized diet and distributional constraints (breeding colonies). Other than fisheries, key predators of forage fish are a few piscivorous fish species including saithe, whiting, mackerel, and horse-mackerel, exploited in turn by fisheries; seabirds and seals have a more modest impact. Size-based foodweb modelling suggests that reducing fishing mortality may not necessarily lead to larger stocks of piscivorous fish, especially if their early life stages compete with forage fish for zooplankton resources. In complex systems, changes in the impact of fisheries on forage fish may have potentially complex (and perhaps unanticipated) consequences on other commercially and/or ecologically important species.

Mortality rates of puffin Fratercula arctica and guillemot Uria aalge and fish abundance in the North Sea

1992 ◽  
Vol 60 (1) ◽  
pp. 39-46 ◽  
Author(s):  
M.P. Harris ◽  
R.S. Bailey
Keyword(s):  
North Sea ◽  
Mortality Rates ◽  
Fish Abundance ◽  
Uria Aalge ◽  
The North ◽  
Fratercula Arctica ◽  
The North Sea

scholarly journals The Algicidal Bacterium Kordia algicida Shapes a Natural Plankton Community

2019 ◽  
Vol 85 (7) ◽  
Author(s):  
Arite Bigalke ◽  
Nils Meyer ◽  
Lydia Alkistis Papanikolopoulou ◽  
Karen Helen Wiltshire ◽  
Georg Pohnert
Keyword(s):  
North Sea ◽  
Algal Blooms ◽  
Plankton Community ◽  
Algicidal Bacteria ◽  
Important Species ◽  
Substantial Impact ◽  
The North ◽  
Algicidal Bacterium ◽  
The North Sea ◽  
Plankton Communities

ABSTRACT Plankton communities consist of complex microbial consortia that change over time. These fluctuations can be only partially explained by limiting resources. Biotic factors such as herbivores and pathogens also contribute to the control of algal blooms. Here we address the effects of algicidal bacteria on a natural plankton community in an indoor enclosure experiment. The algicidal bacteria, introduced into plankton taken directly from the North Sea during a diatom bloom, caused the rapid decline of the bloom-forming Chaetoceros socialis within only 1 day. The haptophyte Phaeocystis, in contrast, is resistant to the lytic bacteria and could benefit from the removal of the competitor, as indicated by an onset of a bloom in the treated enclosures. This cascading effect caused by the bacterial pathogen accelerated the succession of Phaeocystis, which bloomed with a delay of only several weeks in the in situ waters at Helgoland Roads in the North Sea. The algicidal bacteria can thus modulate the community within the limits of the abiotic and biotic conditions of the local environment. Implications of our findings for plankton ecosystem functioning are discussed. IMPORTANCE Plankton communities change on a seasonal basis in temperate systems, with distinct succession patterns; this is mainly due to algal species that have their optimal timing relative to environmental conditions. We know that bacterial populations are also instrumental in the decay and termination of phytoplankton blooms. Here, we describe algicidal bacteria as modulators of this important species succession. Upon treatment of a natural plankton consortium with an algicidal bacterium, we observed a strong shift in the phytoplankton community structure, compared to controls, resulting in formation of a succeeding Phaeocystis bloom. Blooms of this alga have a substantial impact on global biogeochemical and ecological cycles, as they are responsible for a substantial proportion of primary production during spring in the North Sea. We propose that one of the key factors influencing such community shifts may be algicidal bacteria.

scholarly journals Seasonal variations in the occurrence of Vibriovulnificusalong the Dutch coast

1994 ◽  
Vol 112 (2) ◽  
pp. 285-290 ◽  
Author(s):  
J. Veenstra ◽  
P. J. G. M. Rietra ◽  
J. M. Coster ◽  
E. Slaats ◽  
S. Dirks-Go
Keyword(s):  
Seasonal Variation ◽  
Water Temperature ◽  
North Sea ◽  
Seasonal Variations ◽  
Water Samples ◽  
Human Disease ◽  
Sea Water ◽  
Dutch Coast ◽  
The North ◽  
The North Sea

SUMMARYThe seasonal variation in the occurrence ofV. vulnificusin relation to water temperature and salinity was studied along the Dutch coast. In two consecutive yearsV. vulnificusstrains could be isolated in August when the water temperature was highest. The indole-positive strains isolated from North Sea water samples were identical to most strains isolated from human disease and from the environment. However, strains isolated from four of five patients living in countries around the North Sea were different from the North Sea isolates in that they were indole-negative and have a lower NaCl tolerance.

Small-scale modelling of the physiochemical impacts of CO2 leaked from sub-seabed reservoirs or pipelines within the North Sea and surrounding waters

2013 ◽  
Vol 73 (2) ◽  
pp. 504-515 ◽  
Author(s):  
Marius Dewar ◽  
Wei Wei ◽  
David McNeil ◽  
Baixin Chen
Keyword(s):  
North Sea ◽  
Small Scale ◽  
The North ◽  
Scale Modelling ◽  
The North Sea

scholarly journals First report of an idiopathic partial tail myonecrosis in European brown shrimp Crangon crangon caught in the North Sea

2020 ◽  
Vol 138 ◽  
pp. 35-40
Author(s):  
XHC Vermeersch ◽  
A Decostere ◽  
G Vlaemynck ◽  
K Chiers
Keyword(s):  
North Sea ◽  
Distal Part ◽  
Brown Shrimp ◽  
Bacterial Invasion ◽  
Microscopical Examination ◽  
Necrotic Tissue ◽  
Crangon Crangon ◽  
Important Species ◽  
The North ◽  
The North Sea

The European brown shrimp Crangon crangon is an abundant and commercially important species in the North Sea. Currently, there is interest in landing live shrimp to provide fresh animals for a growing market in live brown shrimp. During 4 survival studies between 2014 and 2016, shrimp were collected from commercial trawlers and maintained alive in off-shore facilities. From Day 1 onwards, a minority of shrimp (~2.24%) developed a white discoloration of the abdominal muscles and a depigmentation of the distal part of the abdomen, along with paralysis of the affected tissues and appendages. As the symptoms progressed, a circumferential blackish delineation appeared, creating a distinct boundary between healthy and necrotic tissue. Affected shrimp survived up to 3 wk, although in several animals the distal part of the tail was completely lost. Histological and electron microscopical examination confirmed the myonecrosis. A secondary bacterial invasion of the necrotic muscle was observed in some animals. RT-PCR for infectious myonecrosis virus was negative. The condition appears not to be contagious, based on the feeding of healthy shrimp with necrotic tissue of affected shrimp. Based on these observations, a mechanical cause inflicted during the catching process is proposed.

scholarly journals Recent findings of wild European flat oysters Ostrea edulis (Linnaeus, 1758) in Belgian and Dutch offshore waters: new perspectives for offshore oyster reef restoration in the southern North Sea

2018 ◽  
Vol 148 (1) ◽  
Author(s):  
Francis Kerckhof ◽  
Joop W.P. Coolen ◽  
Bob Rumes ◽  
Steven Degraer
Keyword(s):  
North Sea ◽  
Ostrea Edulis ◽  
Important Species ◽  
Reef Restoration ◽  
The North ◽  
Detection And Identification ◽  
The North Sea ◽  
Feasible Alternative ◽  
Flat Oyster ◽  
The 19Th Century

The European flat oyster, Ostrea edulis, is an emblematic and ecologically important species that was fished to virtual extinction in Belgian and Dutch waters in the 19th century. We report on recent findings of live specimens in Belgian and Dutch waters, an indication for the presence of O. edulis in these waters. Though small, these relict populations provide possibilities for natural recovery of O. edulis reefs in Belgian and Dutch waters, provided the oyster’s habitat requirements are restored (e.g., exclusion of bottom disturbance). We suggest investigating whether a natural, yet slow, recovery using fisheries closures and gravel bed restoration is a feasible alternative to the currently envisaged human-mediated re-introduction of O. edulis in the North Sea. We identify and address the challenge of O. edulis detection and identification as an important issue blurring the true presence and distribution of oysters.

scholarly journals Impact of additional small-scale survey data on the geostatistical analyses of demersal fish species in the North Sea

2005 ◽  
Vol 69 (4) ◽  
pp. 587-602 ◽  
Author(s):  
Gerd Peter Zauke ◽  
Vanessa Stelzenmüller ◽  
Siegfried Ehrich
Keyword(s):  
Survey Data ◽  
North Sea ◽  
Fish Species ◽  
Demersal Fish ◽  
Small Scale ◽  
The North ◽  
The North Sea

scholarly journals JOINT OFFSHORE WIND FIELD MONITORING WITH SPACEBORNE SAR AND PLATFORM-BASED DOPPLER LIDAR MEASUREMENTS

2015 ◽  
Vol XL-7/W3 ◽  
pp. 959-966 ◽  
Author(s):  
S. Jacobsen ◽  
S. Lehner ◽  
J. Hieronimus ◽  
J. Schneemann ◽  
M. Kühn
Keyword(s):  
North Sea ◽  
Wind Field ◽  
Wind Farm ◽  
Offshore Wind ◽  
Small Scale ◽  
Doppler Lidar ◽  
Wind Fields ◽  
The North ◽  
Spatial Coverage ◽  
The North Sea

The increasing demand for renewable energy resources has promoted the construction of offshore wind farms e.g. in the North Sea. While the wind farm layout consists of an array of large turbines, the interrelation of wind turbine wakes with the remaining array is of substantial interest. The downstream spatial evolution of turbulent wind turbine wakes is very complex and depends on manifold parameters such as wind speed, wind direction and ambient atmospheric stability conditions. <br><br> To complement and validate existing numerical models, corresponding observations are needed. While in-situ measurements with e.g. anemometers provide a time-series at the given location, the merits of ground-based and space- or airborne remote sensing techniques are indisputable in terms of spatial coverage. Active microwave devices, such as Scatterometer and Synthetic Aperture Radar (SAR), have proven their capabilities of providing sea surface wind measurements and particularly SAR images reveal wind variations at a high spatial resolution while retaining the large coverage area. Platform-based Doppler LiDAR can resolve wind fields with a high spatial coverage and repetition rates of seconds to minutes. In order to study the capabilities of both methods for the investigation of small scale wind field structures, we present a direct comparison of observations obtained by high resolution TerraSAR-X (TS-X) X-band SAR data and platform-based LiDAR devices at the North Sea wind farm alpha ventus. We furthermore compare the results with meteorological data from the COSMO-DE model run by the German Weather Service DWD. Our study indicates that the overall agreement between SAR and LiDAR wind fields is good and that under appropriate conditions small scale wind field variations compare significantly well.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: A small scale perspective

2006 ◽  
Vol 356 (1-3) ◽  
pp. 275-289 ◽  
Author(s):  
B DANIS ◽  
P WANTIER ◽  
R FLAMMANG ◽  
P PERNET ◽  
Y CHAMBOSTMANCIET ◽  
...  
Keyword(s):  
Heavy Metals ◽  
North Sea ◽  
Small Scale ◽  
Asterias Rubens ◽  
Sea Stars ◽  
The North ◽  
The North Sea
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