Overview of research projects

Funding: Bundesamt für Gewässerkunde, Koblenz, 29.583 EUR

Project Details:
Dietary analysis of otters found dead are the subject of this study. Relevant otters where dissected as part of a previous project that aimed at investigating anticoagulant rodenticides (rat poison) in predators. During necropsies, all stomachs and the intestinal content of otters was sampled, if available. Continuing, all remains found in the gastrointestinal tracts of the otters were specially prepared to allow identification of prey species. Two methods will be used therein: hard part analysis, which targets visible bones, scales etc., and metabarcoding, which identifies prey species genetically. In combination, both methods together will create a realistic overview of the prey spectrum of otters from Lower Saxony. All results will be presented as a short report.

Results:

The results of the hard component analysis confirm fish as the most frequently eaten prey class of otters in Lower Saxony. Furthermore, components of amphibians, plants, arthropods, and very sporadically of birds, mammals and molluscs were detected in the stomachs. The Cyprinidae family was the most frequently identified fish family. That otters are opportunistic predators that feed on a variety of fish species depending on availability in their range (Kruuk, 2006; Buglione et al., 2020) was confirmed by the metabarcoding results. The study was able to show that the combination of hard component analysis and metabarcoding is suitable to break down and describe the feeding ecology of otters in Lower Saxony. While metabarcoding could identify fish species that would otherwise have been overlooked, hard component analysis could provide estimates of the number of prey eaten.

Funding: Common Wadden Sea Secretariat (CWSS), 4.994 EUR

Project Details:
The Quality Status Report (QSR) is commissioned by the Common Wadden Sea Secretariat (CWSS). The report is published at regular intervals and provides information on the current status of the Wadden Sea. In order to be able to present the human impact on this sensitive ecosystem, the latest results from science and research are compiled. The authors are experts from different research disciplines from the three countries over which the Wadden Sea extends - Denmark, Germany and the Netherlands. There are different reports on the various main topics. ITAW coordinated the report for the state of marine mammals.

Results:

https://qsr.waddensea-worldheritage.org/reports/marine-mammals

Funding: Aarhus University, DK, 9.736 EUR

Project Details:
In 2021, data on the abundance and distribution of marine mammals were to be collected as part of an environmental impact assessment. The study area is located in the Kattegat near the Danish island of Hesselø. A new offshore wind farm is to be built there. The main target species of the present survey was the harbour porpoise (Phocoena phocoena).
The flight surveys were conducted by Aarhus University and followed the line transect method. In total, the area was surveyed three times in 2021. ITAW was commissioned by Aarhus University to accompany the planning and organisation of the new survey and to quality assure and evaluate the collected data.

Results:

For the three surveys of the study area, densities and abundances of harbour porpoises were estimated and the inaccuracies (95% confidence intervals and coefficient of variation (CV)) associated with the estimation were determined. The processed data and results were submitted to the client.

Funding: Aarhus University, DK, 4.451 EUR

Project Details:
On behalf of Aarhus University (Denmark), data on the abundance and distribution of marine mammals has been collected annually since 2012. Five Natura 2000 sites in the Danish North Sea and Skagerrak were surveyed in 2020. The main target species was the harbour porpoise (Phocoena phocoena). The flight surveys were conducted by Aarhus University and followed the line transect survey method. ITAW was commissioned to quality assure and evaluate the data collected. For the individual study areas, densities and abundances of harbour porpoises could be estimated and the inaccuracies (95% confidence intervals and coefficient of variation (CV)) associated with the estimation were determined. The processed data and results were submitted to the client.

Results:

Report of the Aarhus University (Denmark)

Videnskabelig rapport fra DCE - Nationalt Center for Miljø og Energi nr. 475

https://dce2.au.dk/pub/SR475.pdf

Funding: UKSH, Institut für Toxikologie und Pharmakologie für Naturwissenschaftler, Kiel, 8.404 EUR

Project Details:
Samples of bycaught common eiders from the danish Baltic Sea, which undergo post-mortem examinations at the Institute for Terrestrial and Aquatic Wildlife Research, are provisioned for toxicological analysis at the Christian-Albrechts-University Kiel.
At the Institute for Toxicology and Pharmacology for Natural Scientists, organ samples of liver, kidneys, muscle, brain and fat as well as bile are analysed for residues of explosive compounds of dumped munition. These are 2,4,6-Trinitrotoluene (TNT) and its derivates, which have been detected in blue mussels (Mytilus edulis) in other studies. The examination of common eider tissues will allow to draw conclusions about possible accumulation in the trophic chain.

Results:

https://doi.org/10.3390/ani12152002

Funding: Aarhus University, DK, 4.451 EUR

Project Details:
On behalf of Aarhus University (Denmark), data on abundance and distribution of marine mammals have been collected annually since 2012. Five Natura 2000 sites in the Danish North Sea and Skagerrak were surveyed in 2021. The main target species was the harbour porpoise (Phocoena phocoena). The flight surveys were conducted by Aarhus University and followed the line transect survey method. ITAW was commissioned to quality assure and evaluate the data collected.

Results:

For the individual study areas, densities and abundances of harbour porpoises could be estimated and the inaccuracies (95% confidence intervals and coefficient of variation (CV)) associated with the estimation were determined. The processed data and results were submitted to the client.

Project Details:
Im Rahmen dieser Untersuchung soll die Digitalisierungsstrategie in Bezug auf die universitäre Lehre an der Stiftung Tierärztliche Hochschule Hannover während der COVID-19-Pandemie, ihre Nachhaltigkeit und Übertragbarkeit auf vergleichbare Situationen untersucht werden.

Funding: Landesbetrieb f. Küstenschutz, Nationalpark u. Meeresschutz Schleswig-Holstein, Tönning, 51.769 EUR

Project Details:
Harbour porpoises are representatives of marine mammal top predators in the North Sea and Wadden Sea. With the amendment of the National Park Act in 1999, part of the national park was explicitly dedicated to the protection of harbour porpoises, since a high density of mother-calf groups was found in this area. As part of the reorganization of the Federal-State Marine Programme (BLMP), a programme for the joint monitoring of marine mammals was agreed in January 2011, which meets the requirements of monitoring in accordance with the relevant European directives and international conventions. The Schleswig-Holstein National Park Administration (NPV) in the Schleswig-Holstein State Agency for Coastal Protection, National Park and Marine Conservation (LKN) is responsible for organizing, implementing and financing the acoustic monitoring of harbour porpoises in this programme. The acoustic surveys for the NPV are carried out by the Institute for Terrestrial and Aquatic Wildlife Research (ITAW) as part of the joint marine mammal monitoring within the BLMP. For this purpose, measuring stations are operated at four defined locations in the Schleswig-Holstein Wadden Sea (Lister Tief, Meldorfer Bucht, Rochelsteert and Westerland). Since this year another measuring station was deployed in the Elbe estuary. The measuring stations are equipped with click detectors (C-PODs), which record the echolocation activity of harbor porpoises. The C-PODs are serviced and data downloaded at regular intervals. The obtained data is evaluated against the background of the optimization of the acoustic monitoring as well as necessary extensions for a permanent operation of the measuring stations. The data from this long-term study will provide information on the possible pattern and tidal dependency of harbor porpoise detections throughout the day and over the course of a year.

Results:

The data analysis showed that harbor porpoises have been detected at all monitoring positions over the study period to date. However, spatial (between stations) and temporal differences (individual years, over the course of a year, over the course of a day) in detection rates were documented. At the station Lister Tief (LT), on the eastern side of Sylt, the lowest detection rates were recorded. The station Westerland (WL), west of Sylt in the whale sanctuary, has the highest detection rates (maximum per day) over the study period. The station Meldorfer Bucht (MB), which is located in the immediate vicinity of Büsum harbour, also showed very high detection rates, with an increasing trend in the summer months. The modelling of the individual stations could clearly show that there is a strong seasonality in the harbor porpoise detections. All stations show a maximum in detections in spring, in the period from mid-March to mid-April. This period is just before the phase of the highest birth rate, which lasts from mid-June to end of July. During this period, increased detections were only detected at station MB. Approximately two months after breeding begins the mating season of harbour porpoises in the North Sea. Within this period, an increased detection was observed at Rochelsteert station (RS) in contrast to all other stations. This could be an indication that the area around the station is used for mating. The calves are suckled for about 10 months, but start feeding independently on solid food, in the form of small shrimp-like crabs (Euphausiidae, e.g., North Sea shrimp), with the age of approximately five months. During this stage, an increase in detection rates was documented at Station LT. It is conceivable that juvenile harbour porpoises visit shallow water areas, such as the area at station LT, to forage on benthic first solid food.

Time of day had little effect on detection rates over the entire study period. However, a pattern in diurnal rhythms with more frequent detections in the morning hours was observed at Station LT. A similar pattern was also evident at station RS, with slightly higher detections throughout the day.

The tidal effect is more pronounced than diurnal patterns and could be observed at high tide or in the phases between high and low tide. Station LT shows increased detection rates just before low tide and a minimum during high tide. When comparing stations WL and RS with MB, an opposite effect is observed. Station MB shows a minimum in detection rates shortly after high tide, wheras a maximum during high tide was present at stations WL and RS.

Harbour porpoises were also detected at the measuring station in the Elbe estuary. The data does not yet allow for modelling over the entire year, as the station was just deployed in summer. However, the tidal effect with a maximum of harbour porpoise detections at high tide and lower detections at low tide has already been documented.

The Wadden Sea monitoring has so far generated robust and continuous long-term data sets up to ten years of harbour porpoise click activity. With these unique data sets, it is possible to generate models that provide information on harbour porpoise presence in the Wadden Sea and the effect of possible environmental parameters. The increase of the data base over the years has shown that the models provide an increasingly clear picture of the effect of abiotic factors on harbour porpoises. The assessments of harbour porpoise presence required by international agreements (MSFD and trilateral agreements) can currently only be carried out on a temporal scale using the acoustic data generated within the project with click detectors. In order to further expand the data base and thus improve the quality for assessment, it is necessary to continue the Wadden Sea monitoring every year.

Funding: Nationalparkverwaltung "Nieders. Wattenmeer" Wilhelmshaven, 38.752 EUR

Project Details:
The aim of the project is a survey of the local grey seal population in the entire Lower Saxony and Hamburg Wadden Sea during the birthing season (November-December) and at the time of the fur change (March-April).
On five trilaterally coordinated dates (three during the birthing season; two during the fur-change period), airborne surveys will be conducted with a single-engine aircraft. During the aerial surveys of the tidal flats, a high-resolution SLR camera will be used to photograph the haul-outs. In order to determine the number of young born as well as the total population, the photos taken are subsequently analyzed on the computer.

Results:

Brasseur S., Carius F., Diederichs B., Galatius A., Jeß A., Körber P., Meise K., Schop J., Siebert U., Teilmann J., Bie Thøstesen C. & Klöpper S. (2021) EG-Marine Mammals grey seal surveys in the Wadden Sea and Helgoland in 2020-2021. Common Wadden Sea Secretariat, Wilhelmshaven, Germany.

https://www.waddensea-worldheritage.org/sites/default/files/Wadden%20Sea_Grey_Seal_Report_2021_0.pdf

Funding: Ministerium für Energiewende, Landwirtschaft, Umwelt, Natur und Digitalisierung, 42.766 EUR

Project Details:
Two populations of harbour porpoise occur in the coastal waters of the German Baltic Sea, of which the "Western Belts Sea population" is significantly larger than the "Central Belts Sea population", which is considered to be in danger of extinction. The habitat of harbour porpoises in the Baltic Sea is intensively affected by human activities and factors that can have a negative impact on harbour porpoise populations. These include commercial shipping, tourist recreational activities, seismic surveys, military activities, fishing, offshore construction, blasting of munitions waste, chemical and pharmaceutical pollution and marine litter. Due to the desired energy turnaround and the accompanying expansion of wind energy, numerous wind farms have already been built in German sea areas in recent years and many more are still planned. There are still large quantities of munitions from the Second World War in the Baltic Sea. In order to exclude any danger to people and machinery, these munitions are often blasted in a controlled manner. These blasts generate very high sound energy levels in the low-frequency range, which can propagate over long distances and have a negative effect on marine mammals. The reception of high sound levels, e.g. during pile driving or blasting, can lead to disturbances in the porpoise's feeding activity or even to hearing injuries. In the Baltic Sea in particular, harbour porpoises continue to be threatened by fishing with gillnets, in which harbour porpoises can end up as unintentional bycatch. In order to warn harbour porpoises of set gillnets, acoustic warning devices are increasingly being used in the German Baltic Sea to warn harbour porpoises of nets. These warning devices (Porpoise Alert = PAL) simulate the communication sound of porpoises. Whether these devices lead to a reduction in bycatch has not yet been conclusively investigated. There is also currently no accompanying research to investigate whether these devices lead to a displacement of harbour porpoises.
Harbour porpoises from the North and Baltic Seas are likely to be in poorer health than animals from Arctic waters, which are currently hardly exposed to anthropogenic factors, as a result of high pressure from human factors. Studies on reproductive capacity and age structure have shown that the mean age at death of female harbour porpoises in the Baltic Sea is only 3.67 (±0.3) years, although harbour porpoises can live 20-25 years. Since females do not reach sexual maturity until they are 4.95 (±0.6) years old, early mortality is serious in terms of population development. Only through continuous monitoring can trends in the occurrence of harbour porpoises be detected.
The aim of this study is to investigate the habitat use of harbour porpoises in the western part of the Baltic Sea by means of "passive acoustic monitoring". For this purpose, harbour porpoise click detectors (C-PODs) will be deployed at a total of four positions to detect the presence of harbour porpoises. The measuring positions are to cover the area of the Schleswig-Holstein Baltic Sea that has not been covered by continuous monitoring so far.

Results:

Report only German

https://www.schleswig-holstein.de/DE/fachinhalte/A/artenschutz/meeressaeuger