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Category: monitoring (Page 1 of 2)

New paper! Influence of environmental conditions, population density, and prey type on the lipid content in the northern Baltic Herring

Our new paper, where we investigated the effects of different environmental stressors on the lipid content of the northern Baltic Herring (Clupea harengus membras) was recently accepted for publication in the Canadian Journal of Fisheries and Aquatic Sciences.

In this study we collected herring samples from local trap net fishermen during 1987-2006 and 2013-2014 and analysed their lipid content and fatty acid composition. We discovered that the average lipid content of herring muscle has decreased on average from 5-6% wet weight (w.wt) to 1.5% w.wt. The decrease in sea water salinity and increased size of the herring stock explained best the declining lipid content. Also,  sea water temperature during January-April also had a significant effect in our modelling. We estimated that the amount of the lipid storage incorporated in the spawning stock decreased by approximately 45% during the study, with respective energy content decreases. Fatty acid composition analysis revealed that herring lipids contained a high proportion of essential fatty acids EPA (20:5n-3) and DHA (22:6n-3), which likely originated from its main summertime prey, the freshwater calanoid copepod Limnocalanus macrurus – a zooplankton species that has become highly abundant in the Bothnian Sea.

Global climate change can affect the energy content of fish by altering their lipid physiology and consumption.The results of this study illustrate that various climate change induced processes are leading to changes in the lipid content of the Baltic Herring and, consequently, to changes in the energy flows of the northern Baltic ecosystem.

Silakka

Herring from the Archipelago Sea. Photo: Johannes Sahlsten

Rajasilta, M., Hänninen, J., Laaksonen, L., Laine, P., Suomela, J.-P., Vuorinen, I. & Mäkinen, K. 2018. Influence of environmental conditions, population density, and prey type on the lipid content in Baltic Herring (Clupea harengus membras) from the northern Baltic Sea. Canadian Journal of Fisheries and Aquatic Sciences (accepted for publication)

Read more about the project:

The Baltic herring project

 

Ways FINMARI infrastructure has improved our research

High-quality research and teaching requires investment in good research infrastructures. The FINMARI consortium was founded in 2013 and since then, with its support, we have been able to modernize and improve our research infrastructure.  Good research equipment help researchers and students across disciplines to study various interesting and important questions, related for example to the climate change. Here we introduce some of the equipment we have recently acquired.

Last week, we visited Tvärminne, the Zoological Station of the University of Helsinki and attended in the FINMARI Researcher Days. During the two-day meeting, we presented our latest work as well as heard many interesting presentations from other FINMARI partner organizations. In the photo, our master’s student Markus Weckström is giving a presentation on his master’s thesis. Photo: Jari Hänninen.

What is FINMARI?

Finnish Marine Research Infrastructure (FINMARI) is a cross-institutional consortium founded in 2013 and coordinated by the Marine Research Centre of SYKE. The consortium assembles research institutes, universities and a state-owned company, all with a strong interest in marine research. The distributed infrastructure network includes field stations, research vessels an multi-purpose icebreakers, laboratory facilities, ferryboxes, fixed measurement platforms and buoys.

Our research vessel r/v Aurelia is a part of the FINMARI infrastructure network.The 18,1 m long vessel hosts small wet and dry labs and is equipped with standard hydrographic and marine biological research and sampling equipment (incl. CTD, sediment corers and grabs, An acoustic Doppler current profiler (ADCP), on-line chlorophyll fluorometer, Meridata digital sonar system and other sonars), weather station, differential GPS, Navi Fisher navigating system. R/v Aurelia operates in the Archipelago Sea.

The latest major additions to our research infrastructure have been a Hydro-Bios Multinet Mini and a Manta trawl. The Multinet allows the collection of 5 parallel horizontal or vertical zooplankton samples (mesh size 100 um) and thereby essentially increases sampling efficiency by allowing the collection of more samples in less time. The Manta-trawl is a horizontal net system (mesh size 335 um), which allows researchers to collect microplastics and plankton from the surface waters.

The multiple plankton sampler on board of r/v Aurelia.

Sampling microplastics in the Arctic with the manta trawl. Did you know that the net was named after the Manta ray due to their similar shape?

In 2015, we acquired 10 aquaria racks. Each rack includes 12 aquaria with a closed water circulation to a flow-through system. Recently the aquaria have been used to study how the projected future salinity conditions of the Baltic Sea will affect the genetics of bladderwrack (Fucus vesiculosus).

University and school courses visiting Seili have been able to use new  improved stereo microscopes since 2016.

In spring 2018, we will also receive a side scan sonar system for shallow water, with which we’ll be able to study for example the bottom morphology of fish spawning grounds. The equipment can also open new research possibilities for example in marine archaeology.

Researchers interested in working  abroad may apply for funding at Assembleplus.eu. Assemble plus provides transnational access to marine biological research facilities and resources. At Seili, we offer a wide variety of services, including access to a brackish-water coastal ecosystem, state-of-the-art experimental facilities, historical observation data, and various research support services. Contact us for more information or stay tuned for new funding calls!

New research project investigates parasites found in the Baltic herring

In the Archipelago Research Institute, the reproductive biology of the Baltic herring (Clupea harengus membras) has been studied for over 30 years, since 1984. During the last few years we have discovered large amounts of parasitic worms in the body cavity of herring, collected from the Airisto Inlet. The phenomenon is new as no worms have been previously discovered in our samples. Dna-analyses conducted by the University of Eastern Finland showed that the parasitic worms are in fact two species (Corynosoma strumosum ja C. semerme), belonging to the phylum Acanthocephala. A new research project, studying the distribution and occurrence of these worms in the local herring, seal and great cormorant populations will begin next summer. 

Acanthocephala, also called thorny- or spiny headed worms, are commonly found in fish and seals. In Finland, 11 species are known to occur. The parasitic worms don’t infect humans. The Baltic herring is a safe and nutritious food fish and no cold treatment is required when preparing the fish.

herring_sample

According to our preliminary studies, in 2014-2015, approximately 15% of herring in the Airisto Inlet were infected by the parasitic worms.

Corynosoma-worms use herring as an intermediate host. The grey seal (Halichoerus grypus) and/or ringed seal  (Pusa hispida) are definitive hosts for the Corynosomaspecies. Of the two seal species, the grey seal is common in the Bothnian Sea and nowadays also in the Archipelago Sea. The steady increase of the grey seal population and its spread to the middle- and inner archipelago might have caused the parasitic infection in herring. The species C. strumosum has also been discovered in  Great Cormorants (Phalacrocorax carbo). Therefore, it is possible that the bird species is also a definitive host as the increase of the cormorant population coincides with the timing of our findings.

herring_sample

Parasitic worms may cause negative effects for commercial herring fishery. Therefore, it is important to understand the extent of the phenomenon and the causes behind it.

The two-year study is funded by the Archipelago Sea Fisheries Action Group (officially Saaristomeren kalatalouden toimintaryhmä in Finnish). The research is carried out together with the Joensuu Molecular Ecology Group of the University of Eastern Finland. The project’s field work begins next summer. The aim is to chart the distribution and occurrence of the parasitic worm species in the local herring population. We will also investigate whether the Great Cormorant is a definitive host in addition to the grey seal.

Stay tuned for updates from the field!

Q&A, What do we do in Seili in winter?

Some of the most frequently asked questions we get is “What is it like to work and live in Seili in wintertime?” “What do you do in Seili during winter?” and “How can I travel to Seili in winter?” The institute has operated in Seili year round since its beginning and our actions are generally governed by the busy summer field season and the more peaceful winter season.

Seili winter

When summer turns to autumn and winter and the ferry m/s Östern, operating between Nauvo, Seili and Hanka, ends its summer season, we turn our focus towards the upcoming winter. Even though the weather might still be sunny and warm, the approaching winter season is obvious as one by one the summer employees leave the island and visiting researchers end their field work and experiments for the year. What remains is the core group that takes care of the infrastructure.

As things slow down on the island, the University campus is starting the new academic year, which means that the number of university board meetings etc. increases exponentially. For this reason, a part of our staff move their office for the winter to the Turku university campus area (Matthias-building) and work in Seili only occasionally.

A great weekend getaway for photographers and astronomical enthusiasts. The city lights won’t bother you here, but instead, pack a  headlamp.

For those who work in Seili full-time year round, the wintertime is devoted for maintenance tasks. During winter, sampling equipment are inspected and, if needed, repaired and calibrated, and lab stores are refilled for the next summer. Our service men, Pete and Kari, also take the Institute’s vessels and boats out of water and make sure they are ready for the next season. This winter, there are also several renovations going on, something new is under construction..

The lights at the workshop don’t go out in winter. The peaceful wintertime is devoted to maintaining the infrastructure at Seili.

In autumn, some of the sampling programs, like the moth monitoring, end when the temperatures fall below 0 degrees. One of last big sampling efforts is the fishing of herring for The Finnish Radiation and Nuclear Safety Authority’s (STUK) monitoring purposes. The water quality monitoring, however, is continued year round, and every ca. 10 days the Institute’s preparator, together with Kari or Pete, travel to the sampling point, located north of Seili, to take water samples and measure the temperature and salinity of the water column. Every month, zooplankton samples are also collected. The wintertime sampling is mainly governed by ice and wind-conditions, but usually only during rasputitsa the monitoring cannot be continued as it is not either possible or safe to travel to the sampling point with a boat, snowmobile or hydrocopter.

Seili winter sampling

Sampling in winter 2006. Exceptionally, the trip from Seili post jetty to the sampling location was done with a hover craft.

It is easy to travel to Seili even in the wintertime. After the summer season, a public ferry, m/s Falkö operates between Nauvo and Seili. The biggest differences is in the timetables, in winter, it is possible to travel to Seili and back only on Tuesday, Wednesday and Friday. The ferry ride also needs to be booked at latest the day before. This winter, the Nauvo guest harbour is also under construction and thus, the ferry operates from Keso shipyard in Ernholm, Nauvo.

Interested in traveling to Seili in winter, but the ferry timetables don’t fit your schedule? We offer transportation services year round. More information and price list here.

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