Section

The Benthos includes the organisms and communities living in and at surface of the sea floor, which are dominated by invertebrates. These organisms are a major food source for fish and ply a major role in remineralisation and flux of organic matter deposited in the sea floor. Benthic ecology is the major topic of the Marine Biology Section.

The major part of the benthic fauna is burried in the sediments and is, thus, called “Infauna”. Endofauna

Profile of the sea floor showing typical infaunal organisms (from Tardent). a) Barnacles (Balaniden), b) Blue mussels (Mytilus edulis), c) Polychaete Lanice conchilega, d) Polychaete Lagis koreni, e) Snail Littorina littorea, f) Rasor clam (Ensis americanus), g) Bivalve Cerastoderma edule, h) Bivalve Scrobicularia plana, i) Bivalve Mya arenaria, k) Polychaet Arenicola marina, l) Polychaete Hediste diversicolor, m) Bivalve Macoma balthica.

The infauna is divided into three different size classes: Macro- and Meiofauna and Microorganisms.
The macrofauna (>0,5 mm) includes polychaetes (Polychaeta), bivalves (Bivalvia), snails (Gastropoda), amphipods (Amphipoda) and echinoderms (Echinodermata).
Extremely small organisms (>63<500 µm) belong to the meiofauna. This interstitial fauna prefers sandy sediments.
Microorganims are protists and bacteria.
The epi- or megafauna (>1 cm) lives at the surface of the sea floor, the organisms are bigger and mobile such as sea stars, swimming crabs and anthozoans.

The sampling of the infauna is carried out with grabs and corer (z. B. Van Veen Grab, Box corer), which are lowered from the research vessel to the sea floor. The standardised grabs provide quantitative data.

Epifauna is sampled with dredges or a 2 m beam trawl. These gears are towed behind the ship. The mesh size of the cod end of the net determines the size of the fauna caught.

Because of their sessile habit, benthic organisms and communities are supposed to be good indicators for marine environmental change. Due to strong natural variability of benthic communities, long-term studies or monitoring is essentiell to detect real long-term trends. Long-term studies are part of our work since 1970s.

• Epifauna Jade since 1972 in the 2nd and 3rd quarters with FK “Senckenberg”
• Infauna off Norderney since 1978 in the 1st, 2nd and 3rd quarters with FK “Senckenberg”
• Infauna Transect from German Bight to Dogger Bank since 1990 in May with FK “Senckenberg”
• In- and Epifauna in 6 Boxes from German Bigth to northern North Sea since 1998 in July/August with FFS “Walther Herwig III”
• In- and Epifauna south-eastern North Sea since 1998 in July/August with FFS “Walther Herwig III”
• Infauna Dogger Bank, per Decade, 1920s, 1950s, 1980s, 1990s, 2000s with FK “Senckenberg”
• Infauna Jade Bay, per Decade, 1930s, 1970s, 2009 with FK “Senckenberg”

Long-term studies carried out in the North Sea revealed that benthic communities in the entire southern North Sea (südlich 58° N) have changed. A 1.5 to 4 fold increase in biomass was found since the 1970 as well as a drecrease in long-living species and an increase in small short-living “opportunistic” species.

Eutrophication and intensive beam trawl fishery are found to be the major reasons for the changes in the benthic system. Beside these anthropogenic impacts climate change affects the North Sea benthos as shown by our studies off the island of Norderney and at the Dogger Bank.

The studies sites reach from coastal regions such as the East-Frisian Wadden Sea and the Jade Bay towards the open North Sea(German Bight, Dogger Bank, Skagerrak and Kattegatt) to deep-sea areas (Arctic Ocean, Mediterranean Sea, South Atlantic).

• In- and epifaunal biodiversity patterns on different temporal and spatial scales
• Long-term studies on the variability of species number, abundance and biomass of in- and epifauna
• The role of environmental factors and food availability for the structure and functionial diversity of benthic communities
• Relationship between different benthic size classes
• Benthic food webs
• Benthic species distribution modelling
• Use of hydroacoustic advices for large-scale benthic habitat mapping
• Anthropogenic effects on benthic communities

BMBF DAM
Funding period 2021-2024
I. Kröncke, A. Vedenin

Coastal waters worldwide are contaminated by munitions from the two world wars (World War I and World War II); in the German part of the North Sea and Baltic Sea alone, there are about 1.6 million tons of munitions. The distribution and condition of the munitions in German waters are not sufficiently known. In addition to the explosion and safety risk, these munitions contain cytotoxic, genotoxic and carcinogenic chemicals in combination with conventional explosives, chemical warfare agents and munitions components. There is increasing interest in the study and removal of underwater munitions due to environmental and health risks and the hazards associated with dredging and increased development of offshore infrastructure related to aquaculture, wind farms, cables, and oil or gas pipelines, as well as increased vessel traffic in general. The goal of CONMAR is to integrate existing and new datasets on historic marine munitions, to combine the expertise and knowledge of German marine science organizations, government agencies, and the private sector to advance our scientific understanding of the role, fate, and effects of munitions in the marine environment, and to provide policy solutions for monitoring and remediation activities in coordination with stakeholders. CONMAR will provide detailed information on the distribution and status of munitions in German waters (specifically for the Baltic Sea) and provide a mechanistic and quantitative understanding of the release, dispersal, dilution/degradation, and transfer of munitions compounds in the food chain, including assessment of their ecological and toxicological impacts. CONMAR will use the results to conduct assessments of remediation approaches based on ecological and socioeconomic considerations. CONMAR will initiate a process of transdisciplinary collaboration among stakeholders and researchers. This should lead to follow-up actions, processes and initiatives that can securely plan and implement remediation of heavily polluted areas in the Baltic Sea. With the implementation of CONMAR, Germany will be in a position to reliably assess reliable findings on the ecological impact of munitions on the oceans.

Senckenberg am Meer will study the effects of munition contaminants on the biodiversity of in- and epifauna communities in the munition sink areas and reference areas.

Cooperation partners: GEOMAR, AWI, GCF, IOW, Senckenberg, Thünen, UBA, UKSH, URO

https://www.geomar.de/news/article/conmar-nimmt-munitionsbergung-in-angriff

NWK, VW Vorab
Funding period 2022-2024
I. Kröncke, W. Stamerjohanns

What exactly is a “good coast“, which shelters us from natural hazards and allows us to live responsible and in tune with nature, embedded within an organic and sustainable cultural landscape?

This hypothesis is investigated by a research collaboration between three universities of Lower Saxony at the North Sea coast between the Ems and Weser estuaries. Ecosystem strengthening coastal protection is the focus of the research project. Within the area of conflicting interests between coastal squeeze and naturally formed coasts, coastal protection structures are constructed. At the interface between land and ocean sea dikes protect the hinterlands with their values against impeding storm surges.

Incremental climatic change, partially enhanced by human activities, results in already measurable consequences such as sea level rise, milder winters and prolonged summer droughts. Consequently, coastal protection concepts require a makeover. Current concepts are solely targeted at flood protection and do not consider any additional benefits for the system. For example, the value of a functional habitat for flora and fauna or touristic development are completely neglected.

How maritime landscapes, such as salt marshes or coastal dunes, can be integrated into current protection approaches is the driving question in the project “Gute Küste Niedersachsen”. What functional benefits, such as added coastal protection through wave dampening or independent system adaptation, they offer is of major importance against the background of ubiquitous climate change. To answer these questions, large scale field laboratories are developed at the North Sea coast by the research partners. Within the field labs, yearlong observations of the foreshore with its halophytes will be acquired. In a subsequent step, these data will be used to build surrogate plant models and mimic nature in hydraulic laboratories to investigate system responses towards extremes in more detail. Finally, technical guidance as well as policy recommendations will be derived for a more integrated coastal protection and management concept.

We will study the changes in the in- and epifauna communities since 1998in the field labs Otzumer Balje und Harle in relation to sea level rise and de-eutrophication. We will also compare the communities in both systems in order to study the effect of an embankment in the Harle on the community structure.

Cooperation partners: Gottfried Wilhelm Leibniz University Hannover, Carl von Ossietzky University Oldenburg – Institute for Chemistry and Biology of the Marine Environment, Technical University Carolo-Wilhelmina Braunschweig

http://gute-kueste.de

BMBF
Funding period 2020-2023
I. Kröncke, A. Singer

The North Sea, as many other marine ecosystems worldwide, is changing rapidly, i.a. driven by changes in human activities and effects of climate change. Decreasing fishing pressure, de-eutrophication due to decreasing riverine nutrient loads from the big rivers, and increasing water temperatures are the most striking changes altering the southern North Sea as a habitat for various species.

Therefore, shifts in the food web can occur through stronger top-down controlled processes (predatory fish) and weaker bottom-up effects (primary production), which have the potential to severely change ecosystem services and the usability of biological resources.

For a better understanding of the consequences of ongoing biodiversity changes for food webs, we will jointly analyse existing long-term datasets of 5 different taxonomic groups (marine mammals, fish, benthos, zoo- and phytoplankton). In addition, we will identify dominant functional characteristics („traits“) and their changes, which will then be implemented as functional groups in a food web model of the Ecopath family, thereby improving the parametrization of the model.

The scenarios for biodiversity changes as well as their effects on food webs and the use of biological resources will be discussed with local and regional stakeholders in the North Sea coastal zone, such as local fisheries, aquaculture companies, and local authorities responsible for tourism and other economic activities. To fulfill these objectives, we will form focus groups and execute case studies. Proposed solutions for ecologically, economically and socially sustainable future use and adaption strategies will be jointly developed.

Cooperation partners: AWI, TI Sea Fisheries, TiHo

https://twitter.com/BioWeb4

https://www.researchgate.net/project/BioWeb-Changes-in-Functional-Biodiversity-and-Food-Webs-in-the-Southern-North-Sea

BMBF
Funding period 2020-2023
I. Kröncke, J. Meyer, A. Brandt, M. Sonnewald, J. Lehnhoff, A. Bartholomä

The German EEZ NATURA 2000 areas Sylter Außenriff-Östliche Deutsche Bucht (SylÖDB), Borkum Riffgrund (BRg) and Doggerbank (Dgb) have been established to protect Red lists and other species and their habitats regarding EU law (Fauna-Flora-Habitat-Directive (FFH-RL 92/43/EWG) und Birds Directive (RL 2009/147/EG)). Fisheries impact in these areas is planned to be excluded in order to achieve the Good ecological status (GES) in these areas.

The project will provide a baseline study fort he three NATURA 2000 areas. The results will enable us to assess the effects of future exclusion of mobile ground fishereis on the communities and their biotops using the BACI approach (Before-After-Control-Impact). We will establish small scale spatial study areas in the NATURA 2000 areas SylÖDB, BRg and Dgb, where we will study the effects of fisheries exclusion and the recovery and succession of benthic communities after the disturbance will stop. Our studies follow a new, holistic-ecosytsem based approach, which includes benthic ecology, plankton ecology, sedimentology, hydroacoustics, microbiology and food web studies.

Cooperation partners: AWI, HZG, HIFMB, TI Sea Fisheries, ICBM

LKN.SH/TI Sea Fisheries
Funding period 2020-2021
Ingrid Kröncke, Vanessa Fromme, Wiebke Stamerjohanns

The aim of this project is to study long-term changes in North Sea fish habitats. This information is needed for the MSRL Assessment.

We will study the benthic food availability for demersal fish in different habitats of the south-eastern and northern North Sea with different environmental conditions. Infauna samples, which were sampled during the „German Small-scale Bottom Trawl Survey“ (GSBTS) since 1998 will be analysed by taxonomical identification of species. We plan to correlate changes in long-term variability of benthic infauna abundance and biomass with those of demersal fish stock.

Cooperation partner: A. Sell, Thünen Institute Sea Fisheries, Bremerhaven

EU
Funding period: 2019-2021
Pedro Martinez Arbizu, Ingrid Kröncke, Magdalini Christodoulou

Several EU directives and OSPAR guidelines require transnational sustainable management of marine resources. Benthic organisms are key components in environmental impact assessments and the Marine Strategy Framework Directive. Currently, indicators are mainly
based on morphological species identification, being time-consuming, labor-intensive and skills reliant. DNA-based tools promise cheaper, faster and more accurate methods, yet, different approaches between countries are used which hamper standard routine application.

GEANS aims to harmonize and consolidate existing genetic tools and methods. Transnational co-operation will create synergies and assure comparability. An open library, linking DNA sequences to species functioning, will guarantee continuity of traditional assessment series. Real time pilot studies, in close cooperation with managers, policymakers and involved stakeholders, will deliver proof of concept on the added value of genetic approaches in environmental health management. A decision support framework will include a fit for purpose choice of genetic tools and protocols, helping to translate genetic results into simple indicators. GEANS will mainstream implementation of fast, accurate, cost-effective DNA-based assessments, enabling national authorities to adapt management measures in a transnational coherent way, resulting in improved management of human activities and protection of the marine environment across the North Sea Region.

Kooperationspartner: ILVO, B; VLIZ, B; Nord University, N; CEFAS, UK; SeAnalytics AB, SE; Aarhus Universitet, DK; Wageningen University, Department of Animal Sciences, NL; Naturalis Biodiversity Center, NL

Lower Saxony Wadden Sea Foundation, Bingo Environment Foundation
Förderperiode: 2019-2021
Anja Singer, Ingrid Kröncke

Das Inkrafttreten der Flora-Fauna-Habitat (FFH)- und Wasserrahmenrichtlinie (WRRL) zur Erhaltung der natürlichen Lebensräume sowie deren wildlebenden Tiere und Pflanzen fordert, den ökologische Zustand des Wattenmeeres und der Ästuare mittels biologischer Indikatoren, wie u.a. Makrozoobenthos, zu bewerten. Grundvoraussetzung für die richtige ökologische Bewertung eines Wattgebietes ist die Ausweisung eines Referenzdatensatzes. Im Sinne der FFH- und WRRL sollte dieser als Grundlage zur Beschreibung eines Referenzzustandes eine möglichst vollständige Erfassung des lebensraumtypischen Arteninventars (Makrofauna, Avifauna) und der lebensraumtypischen Habitatstrukturen (Sandwatt, Mischwatt, Schlickwatt, Seegrasbestände, Miesmuschelbank) aufweisen (Krause et al. 2008). Anhand der Arten, Abundanzen und ggf. Biomassedaten aktueller Untersuchungen kann dieser Referenzdatensatz als Basis für eine Zustandsbeschreibung und Beurteilung naturnaher Wattflächen im Hinblick auf zukünftige klimatische, anthropogene und natürliche Veränderungen verwendet werden.

Kooperationspartner: NIOZ, Texel, NL; Nationalparverwaltung Nieders. Wattenmeer, Wilhelmshaven

DFG Research group
Funding period: 2019-2021
Jana Dewenter, Ingrid Kröncke

Die Motivation für die Forschergruppe DynaCOm ergibt sich vor allem aus dem Fehlen einer trait‐basierten Nahrungsnetzperspektive im räumlichen Kontext. Es bedarf der Information zu mehreren Trait‐Achsen, um für trophisch interagierende Organismen Ausbreitung, Ressourcennutzung und Toleranz bei rapiden Umweltveränderungen vorherzusagen. Diese Information soll in ein räumlich strukturiertes Nahrungsnetz (Meta‐Nahrungsnetz) integriert werden, geleitet von allometrischen (größenabhängigen) und stöchiometrischen (ressourcennutzungsabhängigen) Konzepten (Ziel 1). Die Teilprojekte decken dabei marine und terrestrische Nahrungsnetzkomponenten (Primärproduzenten, Primärkonsumenten, Prädatoren) ab, um eine hohes Maß der Generalisierung über verschiedene Organismentypen zu erlauben.

Daher wurden bereits experimentelle und beobachtende Infrastrukturen im Wattenmeer etabliert, da in dieser Küstenzone terrestrische und marine Nahrungsnetze koexistieren. Außerdem ist das Wattenmeer ein sehr dynamischer Lebensraum, der die Betrachtung existierender Modellvorstellungen außerhalb von Gleichgewichtsbedingugen erlaubt (Ziel 2).

Kooperationspartner: ICBM und IBU Universität Oldenburg, Universität Göttingen, iDiv

SGN since 1978
Ingrid Kröncke, Kerstin Thaler, Marie E. Kaufmann

Since 1978 we study the seasonal variability of macrofaunal species number, abundance and biomass in the subtidal off the island of Norderney. Our data set is one of only few North Sea benthos long-term studies and almost unique due to its methodological constancy.
The statistical data analysis revealed that the increase in macrofaunal species number, abundance and biomass since 1988 is correlated with positive North Atlantic Oscillation Indices (NAOI). Positive NAOIs are related with mild winters, westerly winds and higher storm frequency. Thus, changes in the macrofauna communities are influenced by changes in the hydroclimate of the North Sea, at least in mixed water columns.

SGN since 1990
Julia Meyer, Ingrid Kröncke, Kerstin Thaler

We study the short- and long-term variability of macrofaunal communities along a transect from the inner German Bight towards the Dogger Bank.
At 7 stations samples were taken in 1990 and since 1995 at 4 stations each year in May. Additionally, 3 stations were sampled on a monthly scale from autumn 2000 to spring 2002 to investigate the seasonal variability of species number, abundance and biomass of macro- and epifauna in relation to environmental parameters and food availability.
The results show that seasonal variability is mainly influenced by recruitment in spring. Long-term variability at the study sites was mainly affected by the extreme cold winter 1995/96. Highest intraannual variability was generally found in coastal communities due to higher variability in environmental parameters such as temperature, stratification and food availability in this region. Climatic induced changes in the community structure are evident since 2000.

SGN since 1985
Ingrid Kröncke

The macrofauna communities on Dogger Bank from the 1920s, the 1950s and the 1980s to the 2000s were compared. Five communities with similar spatial distribution throughout the 20th century were identified. The abundance of dominant species in the five communities varied with time. Most obvious in the 1950s was the loss of the extensive Spisula and Mactra patches, which covered most of the shallow parts of the Bank in the 1920s. Since the 1980s, they have been found as juveniles only. The biological regime shift in the late 1980s caused an increase in macrofauna abundance, species numbers, diversity and southern species in most of the communities. The climate regime shift in 2001 had opposite effects, abundance, species numbers, diversity and southern species decreased in most of the communities. The increase in interface feeding species and the decrease in sand licking amphipods in the 2000s especially in the shallow Bank Community give evidence for climate driven changes in water masses, currents, storms, turbidity and food availability via planktonic or benthic primary production. Both, fishing impact and climate change are reasonable to explain the changes in the Dogger Bank macrofauna communities.