Alexander Darr

• PhD
• Senior Researcher at Bundesamt für Seeschifffahrt und Hydrographie

Simple Summary This study provides full-coverage maps of the habitats and biotopes in the German Baltic Sea at an unprecedented level of resolution. We combined geological and biological surveys to map the seabed and collected extensive data to classify different habitats and their inhabitants. Using newly established national guidelines and modell...

This study contributes to a better understanding of geogenic reef distribution in the southern Baltic Sea and highlights the implications of survey-related factors on automated boulder classification when utilizing data from multiple surveys. The distribution of hard grounds and reefs is needed as a baseline for geological and biological studies, b...

Simple Summary An increasing number of different habitats leads to an increasing number of species and has been considered a key driver for biodiversity. However, there is no common understanding on how to measure habitat diversity. In this study, we tested a newly proposed measure of substrate heterogeneity by classifying changes on the seafloor w...

In this chapter, we describe the formation and mapping of marine benthic underwater habitats in offshore waters. We characterize the respective biotopes and discuss the anthropogenic pressures acting upon them. A variety of different classification systems have been developed within the last decades that, depending on the respective aim and scale,...

The short term impacts of fishing pressure were compared with the variability induced by environmental drivers on quantitative benthic community impact indicators. The different pressures were evaluated through comparative multifactor statistical analyses of their effects on macrofauna indicators in a Baltic Sea area with high natural disturbance....

Marine Biotope und Habitatkartierungen

The rare in the German North and Baltic Sea waters and strictly protected sea star Crossaster papposus was found in 2019 and 2021 during monitoring activities in a marine protected area. This unique observation was achieved by using towed camera platform imagery along a transect in the Fehmarn Belt, which allows monitoring of a much larger area of...

The rare in the German North and Baltic Sea waters and strictly protected sea star Crossaster papposus was found in 2019 and 2021 during monitoring activities in a marine protected area. This unique observation was achieved by using towed camera platform imagery along a transect in the Fehmarn Belt, which allows monitoring of a much larger area of...

Military munitions from World War I and II dumped at the seafloor are a threat to the marine environment and its users. Decades of saltwater exposure make the explosives fragile and difficult to dispose of. If required, the munition is blast-in-place. In August 2019, 42 ground mines were detonated in a controlled manner underwater during a NATO man...

Benthic habitats and communities are key components of the marine ecosystem. Securing their functioning is a central aim in marine environmental management, where monitoring data provide the base for assessing the state of marine ecosystems. In the Baltic Sea, a > 50-year-long tradition of zoobenthic monitoring exists. However, the monitoring progr...

1 There is concern across the International Council for the Exploration of the Sea (ICES) region that a consideration of vulnerable components and the wider support mechanisms underpinning benthic marine ecosystems may be lacking from the process of marine protected area (MPA) designation, management and monitoring. 2 In this study, MPAs across si...

Subtidal hard substrate habitats are unique habitats in the marine environment. They provide crucial ecosystem services that are socially relevant, such as water clearance or as nursery space for fishes. With increasing marine usage and changing environmental conditions, pressure on reefs is increasing. All relevant directives and conventions aroun...

Knowledge of spatial patterns in subtidal hard substrate assemblages is necessary for the development of effective marine management strategies. However, patterns are intrinsically scale-dependent, and little is known about the relative importance of vertical and horizontal position changes across scales. In the southwestern Baltic Sea, major physi...

Understanding the distribution and structure of biotopes is essential for marine conservation according to international legislation, such as the European Marine Strategy Framework Directive (MSFD). The biotope 'Sea Pen and Burrowing Megafuna Communities' is included in the OSPAR list of threatened and/or declining habitats. Accordingly, the MSFD p...

Quantitative acoustic marine habitat mapping needs to consider the impact of macrobenthic organisms on backscatter data. However, the sensitivity of hydroacoustic systems to epibenthic life is poorly constrained. This study explores the impact of a benthic community with sparse abundance on seafloor microroughness and acoustic backscatter at a sand...

Benthic monitoring has long traditions in the Baltic Sea and soft-bottom macrofauna was among the first variables to be included in the Baltic-wide HELCOM COMBINE monitoring program. Whereas monitoring methods, programs and assessment procedures are well established for soft-bottom macrobenthic infauna, present marine policies, e.g. the Marine Stra...

Boulders provide ecologically important hard grounds in shelf seas, and form protected habitats under the European Habitats Directive. Boulders on the seafloor can usually be recognized in backscatter mosaics due to a characteristic pattern of high backscatter intensity followed by an acoustic shadow. The manual identification of boulders on mosaic...

1. In this study, non-destructive seafloor imaging techniques were employed to assess the benthic community structure of a recently discovered boulder reef within the central Arkona Basin of the Baltic Sea. 2. Data indicate that geographical isolation, water column stratification and temporary oxygen deficiency create an exceptional reef habitat i...

Quantitative sampling of sessile assemblages on temperate subtidal rocky reefs is expensive and severely time-limited by logistics. However, knowledge about distribution patterns of critical and endangered species and habitats at different spatial scales is needed for effective marine management strategies. To gain information of sessile community...

Anthropogenic pressure on marine coastal ecosystems is increasing and benthic habitats are particularly affected. Effective marine resource management is needed which rely largely on the knowledge of the distribution of critical species and habitats. Rocky reefs are such important habitats, hosting diverse macrobenthic assemblages, which in turn su...

Anthropogenic pressure on marine coastal ecosystems is increasing and benthic habitats are particularly affected. Effective marine resource management is needed which rely largely on the knowledge of the distribution of critical species and habitats. Rocky reefs are such important habitats, hosting diverse macrobenthic assemblages, which in turn su...

Langzeitbeobachtungen von aquatischen Ökosystemen zeigen nicht nur eine hohe Variabilität, sondern auch graduelle Änderungen und sog. Regimeshifts: sprunghafte Änderungen im Funktionieren des gesamten Ökosystems. Sowohl die natürliche Variabilität hydrodynamischer und atmosphärischer Prozesse auf verschiedenen Zeitskalen als auch menschliche Einflu...

Hard-bottom habitats with complex topography and fragile epibenthic communities are still not adequately considered in benthic monitoring programs, despite their potential ecological importance. While indicators of ecosystem health are defined by major EU directives, methods commonly used to measure them are deficient in quantification of biota on...

1. Changes in living conditions caused by natural variability or anthropogenic activities elicit distinct responses of species, populations and communities. Bioindication is the recording of such responses and the entity measured is called a “bioindicator”. 2. A bioindicator can be any relevant component or measure that can be used to estimate the...

Biological long-term data series in marine habitats are often used to identify anthropogenic impacts on the environment or climate induced regime shifts. However, particularly in transitional waters, environmental properties like water mass dynamics, salinity variability and the occurrence of oxygen minima not necessarily caused by either human act...

List of abiotic variables. (XLSX)

Supplementary data. (XLSX)

Derivative indices used. (DOCX)

The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries1. A total of 257 benthi...

Due to increasing pressures on the oceans by human activities, effective conservation measures for marine habitats and biotopes are urgently needed. In order to address requirements such as the protection of ecologically important areas and setting legislations to safeguard the oceans, knowledge of the extent, geographical range and ecological func...

Making use of acquired and sampled data and the chosen biotope classification systems soft bottom biotopes and biotope types could be mapped for both the Baltic and the North Sea areas. Regarding the Baltic Sea the mapping was done according to the classification rules of HELCOM HUB. Accordingly, six levels could be mapped for the entire German Bal...

The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries. A total of 257 benthic...

Evaluating the state of benthic communities has played an important role in water quality assessments. Indices incorporating species sensitivities, richness and densities are commonly applied. In Europe, the importance of benthic indices has increased in the last years with the implementation of the European Marine Strategy Framework Directive (MSF...

Full-coverage maps on the distribution of marine biotopes are a necessary basis for Nature Conservation and Marine Spatial Planning. Yet biotope maps do not exist in many regions. We are generating the first full-coverage biotope map for the German Baltic Sea according to the HELCOM Underwater biotope and habitat classification system (HUB). Specie...

Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as well as the protection of sensitive habitats, taki...

Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as well as the protection of sensitive habitats, taki...

Macrozoobenthic biodiversity is described for waters off Angola, one of the poorest-known marine environments of the world. During research cruises in 2004 and 2011, the shelf region of Angola was investigated at 39 stations in water depths of between 19 and 340 m. Most of the stations were characterised by fine sediments, e.g. silt and sand. In al...

The HELCOM Red List biotopes project proposed a Baltic Sea wide classification consisting of six levels: The HELCOM Underwater biotopes/habitats classification system (HELCOM HUB). We present a case study from the south-western Baltic Sea where we tested the applicability of this system. More than 500 sampling stations were analyzed regarding macro...

The use of static indicator species, in which species are expected to have a similar sensitivity or tolerance to either natural or human-induced stressors, does not account for possible shifts in tolerance along natural environmental gradients and between biogeographic regions. Their indicative value may therefore be considered at least questionabl...

uMuscheln, Seesterne und andere im und auf dem Meeresboden lebende Organismen reagieren auf sich verändernde Salzgehalte, wechselnde Temperaturen und auch auf Eingriffe durch den Menschen. Einige von ihnen werden deshalb dazu verwendet, den Zustand der Ostsee zu bewerten. An dieser Stelle soll dargestellt werden, welche Aussagen von der Struktur de...

The aim of the present study was the development of species-habitat models for four Magelona species (Polychaeta: Magelonidae) found in the German Bight in the SE North Sea. Analyses were based on field data and data obtained from reexamination of material deposited in museum collections. In addition, data on environmental variables were retrieved...

Increasing attention has been paid on the prediction of the distribution of species in relation to environmental conditions in consequence of increasing interests in nature conservation issues behind the background of ecosystem change and spatial planning. Additionally, the developped models may give important information on the preference of the s...

A list of common names of German marine and brackish water molluscs was compiled for the German coastal waters and the exclusive economic zone (EEZ) of the North and Baltic Seas. Main aim of this compilation is to give interested non-professionals better access to and understanding of sea shells and squids. As often long-lived and relatively statio...

The aim of the study was the development of habitat models for Nephtys species (Polychaeta: Nephtyidae). The investigation area was the German Bight, the southeastern part of the North Sea. Models were developed based on field data collected between 2000 and 2006. In addition, data on environmental variables were retrieved from long-term monitoring...

First record of Congeria leucophaeata (Conrad, 1831) in Mecklenburg-Vorpommern (Bivalvia: Dreissenidae). - In the year 2000 at three stations of the lower Region of the River Warbnow in the Hanseatic town Rostock, several specimens of the dreissenid bivalve Congeria leucophaeata were observed....