Ansgar Diederichs

Bio Consult SH

Before piling of offshore wind farm foundations, acoustic harassment devices (AHDs) are used to drive harbor porpoises out of the area where they could suffer injuries. Until 2017, a combination of pingers and seal scarer devices (usually SPL = 174-193 dB re 1 μPa (rms) @ 1m at 1 to 20 kHz depending on the device) was prescribed for mitigation purp...

The utilization of marine renewable energies such as offshore wind farming leads to globally expanding human activities in marine habitats. While knowledge on the responses to offshore wind farms and associated shipping traffic is accumulating now at a fast pace, it becomes important to assess the population impacts on species affected by those act...

The present study is based on a high-quality data set on the distribution and occurrence of divers in the German North Sea over the last 18 years and represents the most extensive data set currently available. For spring, 16 years of data were available (no data for 2006 and 2007), for winter, 17 years were available (2006 missing). This data set c...

All offshore wind farms (OWFs) built in German waters were accompanied by extensive passive-acoustic (CPODs) and aerial-survey-based monitoring programmes to assess potential adverse effects on harbour porpoises. Data collected during piling events of the period 2014-2016, when noise mitigation systems (NMS) reduced average broadband noise levels i...

The seasonal abundance and distribution of harbour porpoise (Phocoena phocoena) in the German North Sea shows a strong variation. However, on a more local scale the seasonal occurrence may follow a constant pattern in consecutive years. We conducted digital aerial surveys covering all seasons over several years to obtain abundance and distribution...

We investigated the disturbance effects of offshore windfarm construction on harbour porpoises using acoustic porpoise monitoring data and noise measurements during construction of the first seven large-scale offshore wind farms in the German Bight between 2010 and 2013. At six wind farms active noise mitigation systems (NMS) were applied during mo...

Effects of shipping traffic on the spatial and temporal distribution of seabirds in the Baltic Sea

Numerous studies based on passive acoustic monitoring by Porpoise Detectors (C-PODs) showed negative effects of pile driving by hydraulic hammers for the construction of offshore wind farms on harbour porpoise (Phocoena phocoena). We studied the efficiency of noise mitigation by two configurations of circular big bubble curtains (BBC1 & BBC2) regar...

During offshore wind farms construction, abundance in harbour porpoise (Phocoena phocoena) is known to be negatively affected. From 2011 to 2013, extensive passive acoustic monitoring was conducted during research projects accompanying the construction of two wind farms in the German North Sea. Using C-PODs, we studied the effect ranges of pile dri...

This study analyses the effects of the construction of eight offshore wind farms within the German North Sea between 2009 and 2013 on harbour porpoises (Phocoena phocoena). It combines porpoise monitoring data from passive acoustic monitoring using Porpoise Detectors (POD data 2010-2013) and aerial surveys (2009-2013) with data on noise levels and...

Acoustic monitoring of harbor porpoises (Phocoena phocoena L., 1758) indicated a strongly reduced disturbance by noise emitted by pile driving for offshore wind turbine foundations insulated by a big bubble curtain (BBC). This newly developed noise mitigation system was tested during construction of the offshore wind farm Borkum West II (North Sea)...

The construction of industrial offshore structures may lead to colonization by a variety of marine organisms resulting in locally enhanced biodiversity and biomass, which may then affect the habitat use and behavior of marine predators. For harbor porpoises high nocturnal echolocation activity was demonstrated near industrial structures and it was...

Unterwasser-Rammarbeiten zur Installation der Stahlfundamente von Offshore-Windenergieanlagen bewirken starke Schallemissionen, die zu Störungen oder Schädigungen von Meeressäugetieren führen können. Daher wird die Entwicklung von Schallminderungsmaßnahmen in Deutschland vorangetrieben. Im Projekt HYDROSCHALL-OFF BW II wurde das Schallschutzsystem...

The first German offshore windfarm (OWF) alpha ventus was constructed between September 2008 and August 2009 in the German Bight north of Borkum, North Sea. It comprises twelve offshore wind turbines on an area of 4 km² and is officially operating since April 2010. Using OWF alpha ventus as a test site, a major goal of this study, being part of pro...

Unterwasser-Rammarbeiten zur Installation der Stahlfundamente von Offshore-Windenergieanlagen bewirken starke Schallemissionen, die zu Störungen oder Schädigungen von Meeressäugetieren führen können. Daher wird die Entwicklung von Schallminderungsmaßnahmen in Deutschland vorangetrieben. Im Projekt HYDROSCHALL-OFF BW II wurde das Schallschutzsystem...

Common Scoter (Melanitta nigra) at the Schleswig-Holstein North Sea coast The Schleswig-Holstein North Sea coast has internatio- nal importance for Common Scoters as a wintering and moulting area. The Agency for Mining, Energy and Geo- logy (Landesamt für Bergbau, Energie und Geologie (LBEG)) gave the permission to extract sea sand to the west of...

Underwater noise emissions from pile-driving during the construction of offshore wind farms can physically harm harbour porpoises in the vicinity of the construction site. In order to avoid injury to these animals, German legislation demands that pile-driving noise must not exceed 160dB re 1µ Pa (SEL) at 750 m distance from the sound source. Before...

Although seal scarers are widely used both to reduce economic losses at fish farms caused by seal predation and to reduce risks posed to marine mammals by offshore pile driving activities, the spatial extent of their deterrent effect on harbour porpoises is still largely unclear. However, this information is crucial to understanding the effects the...

Offshore pile driving, e. g. during wind farm construction, produces substantial noise emissions into the water column, which may harm marine mammals. Therefore, it is common practice to attempt to deter the mammals out of potential danger zones beforehand. Seal scarers are commonly used as a deterrent for harbour porpoises in spite of a lack of cl...

The world’s growing demand for sustainable and environmentally friendly energy has led a growing number of countries to explore the options for the installation of offshore wind farms. In particular, noise emissions during the construction phase, when, in many cases, steel foundations are driven into the seafloor, are expected to cause temporal avo...

The construction of several wind parks in the North and Baltic Sea and the associated pile driving could negatively affect the only resident cetacean species, the harbor porpoise. We studied the efficiency of a Lofitech sealscarer that emits pulses at a main frequency of 14 kHz to temporarily deter harbor porpoises during construction periods in or...

Pile driving during offshore windfarm construction goes along with considerable noise emissions that potentially harm marine mammals in the vicinity and may cause large scale disturbances. Information on the scale of such disturbances is limited. Therefore, assessment and evaluation of the effects of offshore construction on marine mammals is diffi...

We conducted a one year investigation between 2007 and 2008 to assess impacts of sand extrac tion west of Sylt using aerial surveys and passive acoustic monitoring devices (TPODs). The area was surveyed once every month using a double engine aircraft, and porpoise densities were calculated using distance sampling techniques. Porpoises were presen...

During summer 2008, 92 monopile foundations of 3.9 m diameter were rammed into the seabed of the Danish North Sea west of Esbjerg to construct the offshore wind farm Horns Rev II. The aim of this study was to investigate the spatial and temporal scale of the effects of underwater noise from pile driving on harbour porpoises (Phocoena phocoena). Usi...

Harbour porpoise signals consist of directional, high frequency stereotypic clicks which can be logged using T-PODs. Variation in interclick intervals (ICIs) can be used to distinguish different acoustic behaviours. So far, studies on ICI variation are mostly descriptive and the behavioural context in which certain click train patterns are emitted...

This study investigates the effects of an operating offshore wind farm on the temporal and spatial pattern of harbour porpoise acoustic activi ty at a fine scale. The project was conducted jointly by the University of Hamburg and BioConsult SH in the two Danish offshore wind farms Horns Rev (North Sea) and Nysted (Baltic Sea) and financed by th...

Escape distances of wintering divers and seaducks at sea Flight distances of divers Gavia spp., Long-tailed Duck Clangula hyemalis and Velvet Scoter Melanitta fusca were measured during seabird surveys carried out by research vessels in the North Sea and Baltic Sea. Perpendicular flight distance from the course of the vessel was 400 m (median) and...

A standard method has been developed for the aerial surveying of birds and marine mammals, which has been adjusted to the distance-sampling method used by ship surveys. Three observers use dictaphones to make continuous recordings of all animals sighted within three predefined bands on both sides of a twin-engined high-winged aeroplane. The aeropla...