Tvärminne Benthic Ecology Team

22/06/2020

NEW PAPER! Eva Ehrnsten and colleagues review the effects of benthic fauna on nutrient and carbon fluxes in coastal ecosystems and how models of benthic fauna can be incorporated in biogeochemical models to better understand the functioning of coastal systems under environmental change, such as eutrophication and climate change.The study is part of the Baltic Bridge collaboration between the University of Helsinki and Stockholm University.

Read more here: https://www.su.se/ostersjocentrum/english/research/baltic-bridge/potentials-of-mechanistic-modeling-of-biogeochemical-processes-1.504987

And the full article is available here, open access:

Ehrnsten et al. (2020) “Understanding environmental changes in temperate coastal seas: linking models of benthic fauna to carbon and nutrient fluxes”
Frontiers in Marine Science:
https://doi.org/10.3389/fmars.2020.00450

10/06/2020

NEW PAPER from the TZS Benthic Ecology Team! Organic matter rains down from the water column to the seafloor, where the benthic organisms can then utilise it, but very little has been known about the seasonality of this very dynamic process. Iván Franco Rodil and colleagues did a 1-year study where they repeatedly sampled multiple organic compounds to study the seasonal inputs of organic matter from the water column to the seafloor and the uptake in the benthic system by macrofauna. The paper provides new information on drivers of coastal biodiversity and helps understand coastal responses to global change. The study was part of the BONUS-funded COCOA project and the work took place at Storfjärden, our favourite sampling spot!

The paper is now published in Frontiers in Marine Science (open access)
https://doi.org/10.3389/fmars.2020.00404

19/03/2020

NEW PAPER! Storm in winter or flat calm in summer – what happens to the seafloor? Mari Joensuu and colleagues set out to find out!

Coastal erosion and eutrophication are major problems in many areas and therefore it is important to understand processes that regulate sediment erodibility and nutrient release from the sediments in these areas. In this study we looked how the seasonal variation in benthic fauna and sediment properties is reflected in the sediment erodibility and nutrient dynamics in different types of shallow coastal habitats. We found a clear temporal pattern in sheltered muddy sediment, while more dynamic mixed and sandy sediments exhibited less variation in sediment erodibility. Sediments were generally more stable during warmer months compared to colder months. Our results also suggests that sediment resuspension has a minor role for nutrient release in shallow coastal areas.

The open access paper can be found here:
https://link.springer.com/article/10.1007/s12237-020-00726-z

08/11/2019

NEW PAPER! Hanna Sinkko and colleagues analysed how sediment bacterial communities change when stressed by hypoxia (i.e. oxygen deficiency), which is a major environmental problem worldwide. This was done in a field experiment at TZS, where the divers of the Tvärminne Benthic Ecology Team used plastic sheets to artificially induce oxygen deficiency to the seafloor for 0, 3, 7, and 48 days. Subsequently, samples were taken to investigate relationships between bacterial communities, benthic macrofauna and nutrient effluxes across the sediment-water-interface during hypoxic-anoxic stress, considering differentially abundant operational taxonomic units (OTUs). The study suggests that even slightly higher bottom-water oxygen concentrations, which could sustain macrofaunal bioturbation, enable bacterial communities to resist large compositional changes and decrease the harmful consequences of hypoxia in marine ecosystems.

Link to the article in Scientific Reports (“Increasing oxygen deficiency changes rare and moderately abundant bacterial communities in coastal soft sediments”):
www.nature.com/articles/s41598-019-51432-1

13/09/2019

NEW PAPER! How do marine food-webs respond to simultaneous changes in multiple environmental drivers? Eva Ehrnsten, Barbara Bauer and Bo Gustafsson investigated the major pathways through which two interlinked environmental drivers, eutrophication and climate, affect the biomass and community composition of fish and benthic macrofauna in the Baltic Sea by a systematic sensitivity analysis using two food-web models. They found that responses of individual groups were determined by a combination of direct effects (for example physiological) and indirect effects modified through the food-web. In general, increased primary productivity led to biomass increase in all parts of the ecosystem. However, this increase was counteracted by expanding hypoxia. The results indicate that nutrient loads are a stronger driver of change for ecosystem functions in the Baltic Sea than climate change, but it is important to consider the combined effects of these drivers for proper management of the marine environment.

This study is part of the Baltic Bridge collaboration between TZS and the Stockholm University Baltic Sea Centre. It received funding from the EU, the Academy of Finland, and the Swedish Research Council Formas through BONUS (Art 185) as part of the BONUS BALTICAPP project, and from the Swedish Agency for Marine and Water Management.

Ehrnsten et al. 2019. Combined effects of Environmental Drivers on Marine Trophic Groups – A Systematic Model Comparison
https://www.frontiersin.org/articles/10.3389/fmars.2019.00492/full

05/09/2019

NEW PAPER! Leena Virta and colleagues studied the effect of benthic diatom diversity on ecosystem productivity. They collected 78 sediment cores from 17 sites in the archipelago close to TZS, and found exceptionally high diatom diversity: 328 different species. Results showed that diatom diversity, especially functional diversity, most likely forms the lowest boundary for ecosystem productivity. This means that, although productivity can be high even when diatom diversity is low, high diatom diversity supports high productivity. They also found that a heterogeneous environment, such as a coastal archipelago, leads to patchiness in the diversity of benthic diatom communities, and this patchiness is mainly induced by the variation in sediment organic matter content. This study suggests that benthic microorganisms are vital for ecosystem productivity, and together with the substantial heterogeneity of coastal ecosystems, they should be considered when evaluating the potential productivity of coastal areas.

The study was funded by the Walter and Andrée de Nottbeck Foundation, the BONUS COCOA project, the Academy of Finland, and the University of Helsinki.

Press release in Finnish:
https://www.helsinki.fi/fi/uutiset/luonnontieteet/uutta-tietoa-merten-pohjien-piilevista-monimuotoiset-yhteisot-tuottavat-tehokkaimmin-biomassaa

Press release in English:
https://www.helsinki.fi/en/news/science-news/new-information-on-diatoms-of-sea-bottoms-diverse-communities-are-most-effective-in-producing-biomass

Lind to the original article in Ecology:
https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.2765

12/08/2019

NEW PAPER! Iván Rodil and colleagues from Finland and Denmark estimated the respiration rates and secondary production of macrobenthic communities across five key coastal habitats of the Baltic Sea: bare sand, seagrass meadow, mixed macrophyte, Fucus-canopy and blue mussel reef. Our results showed that approximately 12 % and 10 % of the overall soft-sediment metabolism translated into macrofauna community respiration and secondary production, respectively. On the other hand, the hard-bottom habitats exemplified two end-points of the shallow coastal metabolism, with the Fucus-canopy as a high producer and active exporter of organic carbon (i.e. net autotrophy), and the mussel reef as a high consumer and active recycler of organic carbon (i.e. net heterotrophy). Obtaining a better understanding of the across-habitat patterns and seafloor dynamics of coastal habitats is urgent due to current threats of biodiversity loss and habitat homogenization in coastlines around the world.

The Walter and Andrée de Nottbeck Foundation, The Academy of Finland and the University of Helsinki and Stockholm University strategic collaborative research (the Baltic Bridge initiative) funded this work. This study has utilized research infrastructure facilities provided by FINMARI.

https://link.springer.com/article/10.1007/s10021-019-00427-0

09/08/2019

NEW PAPER! Anna Villnäs and colleagues from Finland, Poland and Denmark explored how benthic faunal communities contribute to the coastal nutrient filter across contrasting coastal areas of the Baltic Sea. By using biological trait analysis they estimated faunal bioturbation, stability and total energy- and nutrient contents between coastal areas and inner versus outer sites. Benthic traits indicative of an enhanced nutrient turnover but a decreased capacity for temporal nutrient retention dominated inner sites, while outer sites were often dominated by larger individuals, exhibiting traits that are likely to enhance nutrient uptake and retention. The differences in trait composition between inner and outer sites highlights that disturbances such as eutrophication, which can homogenize benthic communities over large spatial scale, could result in more rapid nutrient turnover rates and low retention of carbon and nutrients. This underlines the importance of preserving healthy benthic communities that can enhance the capacity of the ecosystem to cope with eutrophication.

The study was funded by the Sophie von Julins Stiftelse, the Academy of Finland, and the BONUS COCOA project, which was supported by BONUS (Art 185) funded jointly by EU and the Academy of Finland.

Villnäs et al. 2019. Changes in macrofaunal biological traits across estuarine gradients: implications for the coastal nutrient filter. Marine Ecology Progress Series

https://www.int-res.com/abstracts/meps/v622/p31-48/

30/05/2019

NEW PhD thesis! Johanna Gammal will defend her thesis “Spatial variability in benthic macrofauna communities and associated ecosystem functions across coastal habitats” at the University of Helsinki, on Friday 7th of June 2019, at 12 o’clock, in Auditorium Suomen Laki, Porthania (Yliopistonkatu 3, Helsinki). Professor Martin Solan from the National Oceanography Centre Southampton, University of Southampton, UK, will serve as the opponent.

The aim of Johanna’s thesis was to investigate the links between biodiversity and ecosystem functioning in a variety of field studies in different coastal ecosystems (Tvärminne archipelago in Finland, fjord on the Swedish west coast, and an estuary in New Zealand) in order to understand the context-dependence of these relationships in heterogeneous real-world coastal zones. This included testing the effects of hypoxia, habitat characteristics and background biodiversity on the link between the fauna and the functioning in terms of benthic nutrient recycling.

Her results show that the species identity, abundance and biomass of benthic macrofauna are important for nutrient recycling processes at the sediment-water interface, but that the relationships vary between different types of habitats and that a few dominating species can be more important than species richness per se. These findings are important for improved management and conservation of our complex coastal waters.

The e-thesis can be found here:
https://helda.helsinki.fi/handle/10138/301669

10/05/2019

NEW PAPER! Eva Ehrnsten, Alf Norkko, Bo Gustafsson & colleagues present a new model for macrofaunal biomass and metabolism in coastal soft sediments coupled to a biogeochemical-hydrodynamic model of the Baltic Sea. The results show the important role of macrofaunal respiration in carbon cycling, and how it has increased over time in Tvärminne Storfjärden and around Stockholm University’s Askö research station, Askölaboratoriet. The study is a promising first step to quantify the effects of anthropogenic pressures, such as nutrient loads and climate change, on the future of benthic communities and carbon cycling at the seafloor.

This study is part of the Baltic Bridge strategic research collaboration between the University of Helsinki and Stockholm University, and the study was funded by the EU, the Academy of Finland and Formas through the BalticApp project.

https://doi.org/10.1016/j.jmarsys.2019.04.003

17/04/2019

NEW PAPER! Shallow seafloor habitats are highly biodiverse and productive regions, but there remains considerable uncertainty in their contribution to coastal productivity. Karl Attard and colleagues in the Breathing Seascape project investigated six Baltic Sea habitats over a year using aquatic eddy covariance, a recent technological development that can be applied to a wide range of habitats. The results document the important role of habitats such as seagrass, macroalgae, and mussel reefs for productivity, and they function as 'hotspots' within the coastal zone. The eddy covariance instrumentation was funded through the FINMARI infrastructure network. The Breathing Seascape project is an ongoing collaboration between Tvärminne Zoological Station and the University of Southern Denmark, and funded by the Academy of Finland (Suomen Akatemia) and the Walter and Andrée de Nottbeck Foundation.

Link to the paper in Limnology & Oceanography Letters:
https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lol2.10107

15/02/2019