During the cruise of EMB238 at several stations in Fehmarn Belt area macrofauna samples were collected within the framework of DAM pilot mission project, MGF Baltic Sea, aiming to investigate the impact of bottom trawling fishing in marine protected areas of the German Exclusive Economic Zone (EEZ). The data contains the abundance, biomass and species number. The water depths of all stations was around 24 metres. Samples were obtained using van Veen grab, sieved with 1 mm sieve and fixed with formalin on board. Sorting with microscopy, taxonomic identification, counting and weighing of the species took place in the laboratory.
Plastic litter items (LI) at the seafloor of the Baltic Sea comprises different polymers. 40 LI were collected within fishery catches by bottom trawling during three cruises in 2020 and 2021 and analysed for their polymer types using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, performed on a Spotlight 400 FTIR Imaging System (PerkinElmer Inc., Waltham, USA). The resulting spectra were compared against reference spectra databases. Just LI spectra showing correlation factors above 0.90 compared to the reference spectra were included in the evaluation. Polymer type of plastic LI under investigation could be attributed to six different polymer groups: Polyethylene (PE), polyamide (PA), polypropylene (PP), polyvinylchloride (PVC), polyester (PES) and polyethylene terephthalate (PET). PE was the most frequently identified polymer representing 59% of all plastic items under investigation - followed by PA (17%), PP (12%), PVC (7%) and PES (3%).
NORDSEE: Der Stechrochen war früher vor allem im Sommer in der deutschen AWZ der Nordsee anzutreffen, zu anderen Jahreszeiten hatte die Art hier ihren nördlichen Arealrand. Das Hauptareal dieser lusitanischen Art liegt eigentlich südlich der deutschen Meeresgebiete der Nordsee. Die genauer als das Global Assessment der IUCN auflösende Verbreitungskarte nach Heessen et al. (2015) zeigt aus der eigentlichen Nordsee nur sehr wenige Einzelnachweise (davon keine aus deutschen Meeresgebieten), aber häufigere Nachweise südwestlich davon im Ärmelkanal. Aufgrund der Klimaerwärmung ist es möglich, dass wieder Nachweise der Art aus den deutschen Meeresgebieten bekannt werden bzw. sich dann auch die nördliche Grenze des Areals der Art saisonal längerfristig nach Norden verschiebt, so dass die Art hier auch ihr Hauptareal haben könnte. Wegen der seltenen bzw. fehlenden Fänge ist derzeit eine zweifelsfreie Arealzuordnung der Art für die deutschen Meeresgebiete aber nicht möglich. Der Stechrochen (Abb.: siehe Publikation für Abbildungsnummer), der in der vorliegenden Roten Liste in die RL-Kategorie „Ausgestorben oder verschollen“ fällt, wurde in der vorherigen Roten Liste noch als stark gefährdet geführt. Nach Zidowitz et al. (2017) liegt jedoch seit 1980 kein Nachweis der Art aus den deutschen Meeresgebieten von Nord- und Ostsee mehr vor. Die aktuell verfügbaren Daten bestätigen dies. Die Art wird weltweit als gefährdet (Vulnerable) eingestuft (IUCN 2023). Vor allem indirekte Effekte der Fischerei sind weltweit Gefährdungsursachen des Stechrochens. Aufgrund seines Vorkommens in relativ geringer Tiefe ist er vor allem durch den Beifang in der küstennahen Schleppnetzfischerei bedroht, aber auch durch andere Fischereigeräte wie Langleinen, Spiegelnetze sowie die Ruten- und Leinenfischerei (Zidowitz et al. 2017).
As part of the DAM pilot mission "MGF Ostsee", the meiobenthic communities of a protected area and a reference area in the Fehmarn Belt (Baltic Sea, Germany) were compared, with both study areas currently permitting mobile bottom trawling (MGF). Meiobenthic data were recorded at the major taxon level, with a special focus on the Copepoda Harpacticoida, which was further examined at the species level. This data collection will serve as a baseline for future assessments, after the planned exclusion of MGF in the protected area in 2024 to identify potential impacts of MGF on meiofaunal communities. Meiofauna samples were collected with a multicorer (MUC) on the expedition EMB238 of RV ELISABETH MANN BORGESE from May 26th to June 9th, 2020. From each MUC core the upper 5 cm of the sediment and the supernatant water filtered over 40 µm were used for further processing (area coverage per core: 72.4 cm²). For the morphological approach, this material was fixed with buffered formalin (final concentration: about 4%). Subsequently, in the laboratories of the German Centre for Marine Biodiversity Research (DZMB) in Wilhelmshaven, further treatment took place, namely centrifugation of the rinsed samples with Levasil®, a colloidal gel, to separate the organisms from the sediment (cf. McIntyre and Warwick 1984). Because the sampling material contained an extraordinary abundance of meiofauna, each sample had to be divided into sub-samples before counting and sorting the organisms to ensure efficient processing. This was done using the Jensen splitter (Jensen 1982), which divides a sample into eight equally sized sub-samples. One of these was randomly selected and used for further evaluation.
As part of the DAM pilot mission "MGF Ostsee", the meiobenthic communities of a protected area and a reference area in the Fehmarn Belt (Baltic Sea, Germany) were compared, with both study areas currently permitting mobile bottom trawling (MGF). Meiobenthic data were recorded at the major taxon level, with a special focus on the Copepoda Harpacticoida, which was further examined at the species level. This data collection will serve as a baseline for future assessments, after the planned exclusion of MGF in the protected area in 2024 to identify potential impacts of MGF on meiofaunal communities. Meiofauna samples were collected with a multicorer (MUC) on the expedition EMB238 of RV ELISABETH MANN BORGESE from May 26th to June 9th, 2020. From each MUC core the upper 5 cm of the sediment and the supernatant water filtered over 40 µm were used for further processing (area coverage per core: 72.4 cm²). For the morphological approach, this material was fixed with buffered formalin (final concentration: about 4%). Subsequently, in the laboratories of the German Centre for Marine Biodiversity Research (DZMB) in Wilhelmshaven, further treatment took place, namely centrifugation of the rinsed samples with Levasil®, a colloidal gel, to separate the organisms from the sediment (cf. McIntyre and Warwick 1984). Because the sampling material contained an extraordinary abundance of meiofauna, each sample had to be divided into sub-samples before counting and sorting the organisms to ensure efficient processing. This was done using the Jensen splitter (Jensen 1982), which divides a sample into eight equally sized sub-samples. One of these was randomly selected and used for further evaluation. For the identification and counting of the individuals, we used Leica DMR and Leica DM 2500 microscopes with interference contrast.
As part of the DAM pilot mission "MGF Ostsee", the meiobenthic communities of a protected area and a reference area in the Fehmarn Belt (Baltic Sea, Germany) were compared, with both study areas currently permitting mobile bottom trawling (MGF). Meiobenthic data were recorded at the major taxon level, with a special focus on the Copepoda Harpacticoida, which was further examined at the species level. This data collection will serve as a baseline for future assessments, after the planned exclusion of MGF in the protected area in 2024 to identify potential impacts of MGF on meiofaunal communities. Meiofauna samples were collected with a multicorer (MUC) on the expedition EMB238 of RV ELISABETH MANN BORGESE from May 26th to June 9th, 2020. From each MUC core the upper 5 cm of the sediment and the supernatant water filtered over 40 µm were used for further processing (area coverage per core: 72.4 cm²). For the morphological approach, this material was fixed with buffered formalin (final concentration: about 4%). Subsequently, in the laboratories of the German Centre for Marine Biodiversity Research (DZMB) in Wilhelmshaven, further treatment took place, namely centrifugation of the rinsed samples with Levasil®, a colloidal gel, to separate the organisms from the sediment (cf. McIntyre and Warwick 1984). Because the sampling material contained an extraordinary abundance of meiofauna, each sample had to be divided into sub-samples before counting and sorting the organisms to ensure efficient processing. This was done using the Jensen splitter (Jensen 1982), which divides a sample into eight equally sized sub-samples. One of these was randomly selected and used for further evaluation. For the identification and counting of the individuals, we used Leica DMR and Leica DM 2500 microscopes with interference contrast.
As part of the DAM pilot mission "MGF Ostsee", the meiobenthic communities of a protected area and a reference area in the Fehmarn Belt (Baltic Sea, Germany) were compared, with both study areas currently permitting mobile bottom trawling (MGF). Meiobenthic data were recorded at the major taxon level, with a special focus on the Copepoda Harpacticoida, which was further examined at the species level. This data collection will serve as a baseline for future assessments, after the planned exclusion of MGF in the protected area in 2024 to identify potential impacts of MGF on meiofaunal communities. Meiofauna samples were collected with a multicorer (MUC) on the expedition EMB238 of RV ELISABETH MANN BORGESE from May 26th to June 9th, 2020. From each MUC core the upper 5 cm of the sediment and the supernatant water filtered over 40 µm were used for further processing (area coverage per core: 72.4 cm²). For the morphological approach, this material was fixed with buffered formalin (final concentration: about 4%). Subsequently, in the laboratories of the German Centre for Marine Biodiversity Research (DZMB) in Wilhelmshaven, further treatment took place, namely centrifugation of the rinsed samples with Levasil®, a colloidal gel, to separate the organisms from the sediment (cf. McIntyre and Warwick 1984). Because the sampling material contained an extraordinary abundance of meiofauna, each sample had to be divided into sub-samples before counting and sorting the organisms to ensure efficient processing. This was done using the Jensen splitter (Jensen 1982), which divides a sample into eight equally sized sub-samples. One of these was randomly selected and used for further evaluation. For the identification and counting of the individuals, we used Leica DMR and Leica DM 2500 microscopes with interference contrast.
Fecundity of marine fish species is highly variable, but trade-offs between fecundity and egg quality have rarely been observed at the individual level. We investigated spatial differences in reproductive investment of individual European sprat Sprattus sprattus (Linnaeus 1758) females by determining batch fecundity, condition indices (somatic condition index and gonadosomatic index) as well as oocyte dry weight, protein content, lipid content, spawning batch energy content, and fatty acid composition. Sampling was conducted in five different spawning areas within the Baltic Sea between March and May 2012. Sampling was conducted in the Baltic Sea during three cruises of the German RV “Alkor” in March (https://www2.bsh.de/aktdat/dod/fahrtergebnis/2012/20120331.htm), April (http://dx.doi.org/10.3289/CR_AL390), and May (http://dx.doi.org/10.3289/CR_AL392) 2012. Five different areas were sampled: KB, AB, Bornholm Basin (BB), Gdansk Deep (GD), and Gotland Basin (GB). Fish were caught with a pelagic trawl. Trawling time was in general 30 minutes per haul. The total lengths (TL, ±0.1 cm) of at least 200 sprat per haul were measured for length frequency analysis. Only female sprat with ovaries containing fully hydrated oocytes were sampled, running ripe females were rejected to avoid possible loss of oocytes, as this would lead to an underestimation of batch fecundity. Sprat were sampled immediately after the haul was on deck and stored on crushed ice. The sampled fish were weighed (wet mass WM, ±0.1 g) and measured (TL, ±0.1 cm), and their ovaries were dissected carefully. Oocytes were extracted from a single ovary lobe, rinsed with deionized water, and counted under a stereo microscope (Leica MZ 8). A counted number of oocytes (around 50 oocytes per fish) were transferred to pre-weighed tin-caps (8 x 8 x 15 mm). These samples were used to determine the oocyte dry weight, lipid content, and fatty acid composition. In addition, a counted number of oocytes (around 10 oocytes per fish) were sampled in Eppendorf caps for determination of protein content. Oocyte samples were stored at -80 °C for subsequent fatty acid and protein analysis in the laboratory. Finally, both ovary lobes were stored in 4% buffered formaldehyde solution for further fecundity analysis. Ovary free body mass (OFBM, ±0.1 g) of sampled frozen fish and fixed ovary mass (OM, ±0.1 g) were measured (Sartorius, 0.01 g) in the laboratory on land, to avoid imprecise measurements due to the ship's motion at sea. Absolute batch fecundity (ABF) was determined gravimetrically using the hydrated oocyte method suggested by Hunter et al. (1985) for indeterminate batch spawners. For ascertainment of the relative batch fecundity per unit body weight (RBF), ABF was divided by OFBM. Further, a condition index (CI) was determined: CI = (OFBM/〖TL〗^3 )× 100. A gonadosomatic index (GSI) was calculated with the following formula: GSI = (OM/OFBM)× 100. Oocyte dry weight was determined to the nearest 0.1 µg (Sartorius SC 2 micro-scale), using the samples stored in pre-weighed tin caps, after freeze-drying (Christ Alpha 1-4) for at least 24 hours. After subtracting the weight of the empty tin cap, the average oocyte dry mass (ODM) was then calculated by dividing the total weight by the number of oocytes contained in the tin cap. The fatty acid signature of oocytes was determined by gas chromatography (GC). Lipid extraction of the dried oocytes was performed using a 1:1:1 solvent mix of dichloromethane:methanol:chloroform. A five component fatty acid methyl ester Mix (13:0 - 21:0, Restek, Bad Homburg, Germany; c = 8.5 ng component µl-1) was added as an internal standard and a 23:0 fatty acid standard (Restek, Bad Homburg, Germany, c = 25.1 ng µl-1) was added as an esterification efficiency control. Esterification was performed over night at 50 °C in 200 µl 1% H2SO4 and 100 µl toluene. The solvent phase was transferred to 100 µl n-hexane and a 1 µl aliquot measured in a Thermo Fisher Trace GC Ultra with a Thermo Fisher TRACETM TR-FAME column (10 m*0.1 mm*0.2 µm). For more details on sample preparation and GC settings, see Hauss et al. (2012). The total lipid content per oocyte was determined by adding up the weights of all detected fatty acids. To ensure comparability with past studies, results for FA are given as a percentage of the combined weights of all detected FA. An average of 10 oocytes were transferred to 5*9 mm tin cups (Hekatech) and dried at 50 °C for >24 h. Total organic carbon (C) and nitrogen (N) content was measured using a Thermo Fisher Scientific Elemental Analyzer Flash 2000. From the total amount of N in the sample, the oocyte protein content was calculated according to Kjeldahl (Bradstreet, 1954), using a factor of 6.25. The oocyte gross energy content was calculated on the basis of measured protein and lipid content, which were multiplied with corresponding energy values from literature. The measured amount of proteins per given oocyte (P, mg) was multiplied by a factor of 23.66 J mg-1 and was added to the total amount of lipids per oocyte (L, mg) multiplied by 39.57 J mg-1 (Henken et al. 1986). Consequently, the oocyte energy content of each individual female sprat was multiplied by its relative batch fecundity in order to obtain a standardized estimate of the total amount of energy invested into a single spawning batch (SBEC, J g-1 OFBM): SBEC = [(P × 23.66 (J )/mg)+(L × 39.57 (J )/mg)]× RBF
In the framework of research on impacts of trawling in the western Baltic Sea (DAM pilot mission MGF Baltic Sea), we investigated the population structure of the benthic key species Mya arenaria by measuring shell length to provide the size-frequency distribution in the marine protected area of Oderbank in the Southern Baltic Sea from June 2021. We obtained samples using vanVeen grabs inside the marine protected areas and reference areas nearby.
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