Arbeitsgruppe Ökologie benthischer Organismen - Aktuelle Projekte
Marine Bivalves of Namibia
Duration: 2004 - 2023
This book deals with the Bivalvia of Namibia. Historically, Mollusca of the Namibian coastline have not been systematically studied and when compared to the neighbouring South Africa and Angola, relatively few species are known. The waters of Namibia are one of the deepest gaps of knowledge in World faunistic records. The present book brings together for the first time all previous knowledge from this region with results of extensive recent research. The marine bivalve fauna of Namibia has been illustrated and described using samples mainly colected by German reasearch cruises. The bivalve inventory includes a significant number of recently described species. This book will be particularly useful for hobby biologists, students and marine scientists who study offshore fauna of western Africa and that of Namibia particular.
This handbook is expected to be published by ConchBooks by the end of 2023.
Zettler, M.L., Hoffman, L. 2023: Marine Bivalves of Namibia. Conchbooks, Harxheim (in preparation)
MAPUCHE - Impact of pelagic Anoxia in the Upwelling Area off Concepción and in a pristine anoxic Fjord, and the postglacial Development of the Patagonian Fjord Region of Chile
Macrozoobenthic communities along the transect off Concepción Bay
Duration: 2023 - 2026
Oxygen-deficient areas in oceans are a global problem. The reasons for this are manifold (Vaquer-Sunyer & Duarte 2008). Persistent low oxygen concentrations result in so-called oxygen minimum zones (OMZ) where bottom-water oxygen concentrations on the seafloor are per definition permanently below 0.5 ml l-1. Anoxic conditions like in the waters off Concepcion Bay normally reaching lethal concentrations for most eukaryotes (Schulz et al. 1996, Vaquer-Sunyer & Duarte 2008). Because of the high biomass of Thioploca populations, they may play an important role in controlling the biogeochemistry of sediments in the oxygen minimum zone off Chile and Peru (Jorgensen & Gallardo 1999), the development of toxic hydrogen sulphide is hampered. In the sea floor off Concepción, the Thioploca spp. transport large amounts of nitrate stored in the vacuole from the bottom water into the sediment, thereby increasing the total nitrate pool of the sediment by up to 100-fold (Thamdrup & Canfield 1996). Especially in the summer the oxygen concentration in the investigation area reach near zero (Schulz et al. 1996).
The core areas of OMZs have been subject to studies concerning ecological consequences of permanent low oxygen (e.g. Diaz & Rosenberg 2008, Stramma et al. 2012). For Namibia there have been some investigations focusing on benthic macrofaunal diversity, community structure and adaptation mechanisms in the OMZ (e.g. Zettler et al. 2009, Zettler & Pollehne 2013, Zettler et al. 2013, Eisenbarth & Zettler 2016, Amorim et al. 2021, 2022, Amorim & Zettler 2023). In the OMZ of Chilean waters, especially off Concepción and therefor in our investigation area, investigations were done by e.g. Gallardo et al. (2004), Palma et al. (2005) and Thiel et al. (2007). These and other studies concluded that organisms that survive both normal oxygen supply and potentially long periods of hypoxia, e.g. from upwelling events, can benefit from an abundant food supply and build up high densities and biomass. Dominant macrofaunal species of OMZ boundaries have been studied rather selectively. The main aim of our subgroup was to analyse the macrobenthic diversity in the core area of the central Chilean OMZ and later to compare with results obtained from the Namibian OMZ.
Förderung durch: DFG und IOW
ArKoBi - Untersuchungen zum Beitrag von Arctica islandica zur Kohlenstoffspeicherung und Biodiversität in der Ostsee
Duration: 01.10.2023 - 30.09.2026
Das Projekt ArKoBi untersucht inwieweit die Islandmuschel Arctica islandica bzw. ihre assoziierten Biotope eine Rolle als Kohlenstoffsenke (d.h., Blue Carbon) spielen und wie sich der Klimawandel und anthropogene Nutzungen auf deren Biodiversität, Reproduktion und Populationsstruktur und der damit verbundenen Kohlenstoffspeicherkapazität auswirken. Dies hat nicht nur Relevanz hinsichtlich des Arten- und Biotopschutzes, sondern soll auch für den bundespolitischen Zielen zur Erhaltung der Biodiversität und zum Klimaschutz beitragen. ArKoBi bearbeitet drei Schwerpunktthemen: 1) Die ökologischen Funktion von A. islandica und ihren assoziierten Gemeinschaften als Kohlenstoffsenke oder möglicherweise auch Kohlenstoffquelle auf Organismen- und Gemeinschaftsebene, 2) Die Populations- und Reproduktionsdynamik von A. islandica in der Ostsee, insbesondere im Naturschutzgebiet (NSG) „Fehmarnbelt“, deren Entwicklung mit zunehmenden Umweltveränderungen und anthropogenen Nutzungen sowie die Konsequenzen auf die Kohlenstoffspeicherkapazität der Habitate, 3) Die Frage ob A. islandica aus Nord- und Ostsee genetisch unterschiedliche Populationen darstellen und die Ostseepopulation sich selbstständig reproduziert. Das Projekt ArKoBi vereint Grundlagenforschung mit Meeresnaturschutz und ermittelt das Potenzial zu einem weiteren Blue Carbon – Ökosystem in der Ostsee. Die Erkenntnisse können dazu dienen, mögliche Schutzmaßnahmen abzuleiten, um die A. islandica-assoziierten Biotope sowohl für den Klima- als auch für den Biodiversitäts- und Biotopschutz zu erhalten.
Förderung durch: Bundesamt für Naturschutz
Ansprechpartner: Dr. Michael L. Zettler
Marine Bivalvia of Germany
Especially since the beginning of the 1990s, due to the increase of offshore activities associated with wind mill farms, gas pipelines and oil fields and the consequent need for environmental impact assessments, the demand for knowledge of benthic residents, their distribution and ecological needs has increased. There is more than one reason to present a new key book on bivalves for the German parts of the North Sea and Baltic Sea. First, it is an attempt to consider all marine species observed at least once in the whole catchment area. All species are figured and described comprehensively and their distribution is given in a map. Second, due to the rapid increase of non-indigenous species, we included species that seem to be in the process of becoming established as well as those that already are. The reader now has the opportunity to rely on one monograph rather than having to combine several well-known handbooks from neighbouring areas (see above) or to search in several publications dealing with a single species.
The present handbook will be published in the famous series “Die Tierwelt Deutschlands und der angrenzenden Meeresteile”, which did not yet contain the marine bivalves.
Zettler, M.L., Alf, A. 2021: Bivalvia of German marine waters of the North and Baltic Seas. Conchbooks, Harxheim: 329pp [Dahl, F.: Die Tierwelt Deutschlands 85. Teil] https://www.conchbooks.de/?t=53&u=49452
Potential effects of closure for bottom fishing in the marine protected areas (MPAs) of the Baltic Sea - WP3: Makrozoobenthos
Duration: 1.3.2020 – 31.03.2025
MGF-Ostsee is a pilot project of the “Deutsche Allianz Meeresforschung” (DAM), consisting of a consortium of seven research institutes (IOW, University of Rostock, University of Cologne, Thünen Institute, GEOMAR, DZMB, GFZ). It aims to carry out a comprehensive study of benthic communities and sediment functions in habitats affected by mobile bottom trawl fisheries (MGF) in Marine Protected Areas (MPA) of the German EEZ of the Baltic Sea and quantify the potential changes in these areas after MGF has been excluded. By comparison with reference areas outside the MPAs and in combination with experimental studies, an assessment of the influence of MGF on benthic and demersal biocenoses and ecosystem functions in the Baltic Sea shall be established. Combined investigations of sedimentological, micro- and macrobiological and biogeochemical parameters are planned inside and in the reference areas outside of the three MPAs: “Fehmarnbelt”, “Oderbank” and “Westliche Rönnebank”.
Macrozoobenthos has ecological importance in the food web, is one of the main mediators for biogeochemical processes (metabolism) in the sediment, bioturbation activity, resuspension and deposition, it has regulating properties for microorganisms and is often an important component of the bentho-pelagic coupling in coastal waters. In addition to the target species of mobile bottom-contact fishing, macrobenthic organisms are those that are directly and visibly damaged. Tolerance to fishing pressure and dynamics of (re-)colonization after its exclusion are strongly influenced by the taxonomic composition and habitat properties (especially substrate). WP3 aims to detect short and medium-term effects as well as the regeneration times of macrobenthic communities with a special focus on functional aspects, bioturbation and key long-lived species population dynamic (Arctica islandica).
Mapping of habitats (biotopes) and their living communities at the sea floor along the coasts of Mecklenburg-Vorpommern
Benthic communities are an important interface between fluxes of the water column and the sea floor and are sensitive to changes in both compartments. Based on this ecological function and the slow mobility of most benthic species, they play a special role in assessing anthropogenic influences on marine ecosystems. Therefore, the state of benthic communities represents a basis for water quality assessments and is considered in Descriptor 1 ‘biodiversity’, Descriptor 2 ‘non-indigenous species’ and in Descriptor 6 ‘sea-floor integrity’ of the European Marine Strategy Framework Directive (MSFD).
The ATLAS project is funded by the „Landesamt für Umwelt, Naturschutz und Geologie Mecklenburg-Vorpommern (LUNG M-V)“ and the European Maritime and Fisheries Fund (EMFF). In the framework of the project habitat mapping in the coastal water of Mecklenburg-Pomerania is conducted to create a basis for assessment. In general, Specially Protected Habitats by law (Section 30 of the Federal Nature Conservation Act) and Broad Habitat Types (BHT) are distinguished. This leads to higher resolution mapping within protected areas and lower resolution mapping in broad habitats. Within the ATLAS project three focus areas were defined in the coastal waters of Mecklenburg-Western Pomerania, being located in the Bay of Wismar, Darss Sill and Plantagenetgrund.
For the mapping of the sea floor, acoustic data has to be collected first by using side scan sonar and multibeam echosounder in yet uncharted areas. Macrobenthic communities are sampled by Van Veen grab in sandy to gravel sediments and scratch samples are taken by divers on hard bottom substrate. Secondly, in large areas dominated by homogeneous soft substrates, the existing database of macrobenthic communities is complemented by additional sampling stations. Low resolution biotope maps will be delineated using predictive modelling. The recorded data will be used to apply and develop state of the art habitat classification models based on acoustic as well as macrobenthic data over a large-scale area in the Baltic Sea.
EVAR-WP7 (Adaptation of macrozoobenthic species to fluctuating oxygen concentrations and their effect on benthic fluxe)
- Duration: 01.01.2019 - 31.12.2022
- Workpackage-PI: Dr. Michael L. Zettler
- Funded by: Bundesministerium für Bildung und Forschung (BMBF)
The coe areas of oxygen minimum zones (OMZs) have been subject to studies concerning ecological consequences of permanent low oxygen. The boundaries of OMZs, however, have not been considered as intensely despite their importance with regard to climate change and expansion of OMZs. Several studies concluded that organisms that are able to simultaneously cope with potentially long-lasting hypoxic periods and intense oxygen input e.g. by upwelling events, can build up high densities and biomass if food supply is abundant. Given the high variety of adaption mechanisms to these conditions, successful organisms in and along OMZs likely rely not only on one mechanism, but rather combine several strategies such as, for example, morphological and behavioural traits. In general, the boundaries of the Benguela Upwelling System have been poorly investigated in terms of species inventory, but during preliminary investigations we have observed that certain species occur with highest biomass directly at the edges of the OMZ. Therefore, we now aim to address the question:
By which mechanisms and up to which extent can abundant macrobenthic species survive fluctuations in oxygen availability and how does their activity affect benthic fluxes?
To clarify this, we will initially investigate the distribution of macrobenthic organisms along the transect with changing availability of oxygen in the bottom water. In addition, we will assess the abundance of macrobenthic species in the in situ and ex situ experiments planned to quantify benthic fluxes. This will reveal how the composition and activity of benthic macro organisms affect the fluxes between the sediment and water column. Furthermore, we will conduct targeted incubation experiments with selected, highly abundant species to determine how long they can survive without oxygen and their activity under fluctuations of oxygen availability on different time and concentration scales. This will contribute important boundary conditions for implementation of bioturbation in the benthic modelling work.
Several new species for science could be observed and described during the last years (2009 to 2023).A tabular overview of the species and where they were published can be found HERE.
It is part of a successive series of projects funded by the German Federal Agency for Nature Conservation (BfN) with the goal to establish a sound scientific basis for the implication of relevant European Marine Directives with regard to benthic habitats. Within the project, we will continue our investigations on the spatial-temporal variability of the benthic communities in offhsore areas with a focus on special habitats such as boulder fields and exposed coarse substrates. Our work includes the mapping of benthic habitats on different spatial scales as well as the establishment of new monitoring programmes. We also will apply our findings on common assessment indicators and suggest alternative indicators if required. The analysis will be done in close cooperation with national and regional expert groups and consequently will be integrated into the national and regional discussion on the implementation of European Marine Strategy Framework Directive and the Habitats Directive.