Henri Sumelius

• PhD
• Project researcher at Åbo Akademi University

Marine biodiversity loss poses significant ecological and socio-economic challenges. This paper examines how coastal biodiversity loss is expressed and outlines implications for management. Synthesizing scientific literature on biodiversity change in the well-studied Finnish coastal waters (Baltic Sea) as a case study, we show that biodiversity los...

[report in Finnish, summary available in English at https://luontopaneeli.fi/wp-content/uploads/2024/03/finnish-nature-panel-publications-1a-2024-marine-biodiversity-loss.pdf]. Tällä raportilla täytetään tietopuutteita matalien rannikkoalueiden vedenalaisen luonnon osalta. Raportti perustuu olemassa oleviin tutkimustietoihin rannikon vedenalaisen...

The Finnish Nature Panel has compiled the first comprehensive report on changes in the underwater littoral zone. Rapid and cost-effective research-based action is needed to reverse the negative trajectory of coastal nature. Comprehensive assessments of changes in biodiversity and how these changes occur in shallow littoral areas have not previously...

The aim of this report is to assess the status of sea trout rivers and populations in the Baltic Sea region and provide an overview on the impacts on Baltic Sea sea trout caused by recreational fisheries. The outcome of this assessment highlights the current situation with a considerably high share of rivers still failing to reach a good status, a...

The report presents a background overview, summary results and developed bsst practices and recommendations for successful river restoration projects in the Baltic Sea region. The report focuses on river restorations with primary objectives to improve migratory fish populations, especially sea trout. This report is compiled within the EU Interreg...

Initiated by signs of drastic declines of once abundant flounders in the northern Baltic Sea, this thesis characterised/quantified these declines and studied their potential reasons. Multiple approaches were used to describe population trends, reveal intricacies in stock structure, and assess links to key environmental drivers. The results from the...

Recent years have brought the realization that evolutionary changes driven by selection can occur in ecological time scales. However, recent evolutionary events can be hard to detect and may easily go unnoticed. For harvested species, such cryptic diversity may lead to suboptimal management. These points are illustrated by the two flounder species...

Unobserved diversity, such as undetected genetic structure or the presence of cryptic species, is of concern for the conservation and management of global biodiversity in the face of threatening anthropogenic processes. For instance, unobserved diversity can lead to overestimation of maximum sustainable yields and therefore to overharvesting of the...

The European flounder Platichthys flesus (Linnaeus, 1758) displays two contrasting reproductive behaviors in the Baltic Sea: offshore spawning of pelagic eggs and coastal spawning of demersal eggs, a behavior observed exclusively in the Baltic Sea. Previous studies showed marked differences in behavioral, physiological, and life-history traits of f...

Many coastal and offshore fish species are highly dependent on specific habitat types for population maintenance. In the Baltic Sea, shallow productive habitats in the coastal zone such as wetlands, vegetated flads/lagoons and sheltered bays as well as more exposed rocky and sandy areas are utilised by fish across many life history stages including...

Significance Divergent selection can lead to the evolution of distinct species, a process known as ecological speciation. Evidence for ecological speciation in the marine environment is scarce, and the few known examples have happened within a time frame of hundreds of thousands to millions of years. We present evidence that European flounders in t...

Metacommunity ecology recognizes the interplay between local and regional patterns in contributing to spatial variation in community structure. In aquatic systems, the relative importance of such patterns depends mainly on the potential connectivity of the specific system. Thus, connectivity is expected to increase in relation to the degree of wate...

Non-metric multidimensional scaling ordination of the 21 study beach sites. a) Environmental resemblance matrix (Euclidean distance calculated from replicate site samples to centroids) and b) Taxa resemblance matrix (Hellinger-transformed and Euclidean distance calculated from replicate site samples to centroids). S: stress. (PDF)

Relationships between the community similarity matrix (Hellinger-transformed and Euclidean distance), environmental distance matrix (Euclidean distance) and distance matrix (nearest site to site distance), respectively. Each dot represents the relationship between 2 of the 21 beach sites and visualizes the relationship between two different distanc...

Depth structures aquatic habitats, creating substantial differences in the species composition of underwater communities even at small intervals. Those communities also undergo considerable cyclic variation annually. In this study, we surveyed variation in the vertical distribution of fish in a shallow (20 m) coastal basin in the northern Baltic Se...

We studied seasonal and small-scale spatial variation in fish assemblage structure in the northern Baltic Proper archipelago. The study was conducted in a shallow coastal basin during three consecutive production-seasons. The structure of the fish assemblage changes significantly seasonally, from early summer (May–June) to late summer (August–Septe...