Jani Heino’s research while affiliated with Finnish Environment Institute and other places

Setting reserves or implementing fishing bans in certain areas has become a popular approach to enhance the recovery of disturbed populations and communities due to overfishing. Evaluating the effectiveness of such management measures primarily relies on taxonomic diversity, yet changes in taxonomy-based metrics may not be easily visible even in decadal periods. It has been suggested that functional diversity could outperform taxonomic diversity in capturing early signs of community changes following fishing bans. Here, using a before-and-after comparison methodology, we assessed the recovery of fish communities in the Chishui River basin, an important tributary of the Yangtze River, after seven years of implementation of the “10-year fishing ban” policy. Following the ban, fish community composition and abundance showed no significant changes, but biomass increased significantly. Taxonomic α-diversity (species richness, Simpson, and Margalef indices) and functional α-diversity (functional richness, imbalance, and dispersion indices), as well as taxonomic and functional β-diversity (including turnover and nestedness components), did not change significantly after the ban. Moreover, results from single-trait-based community-weighted mean (CWM) implied an initial recovery of fish communities after the ban, with a significant increase in CWM of maximum body length, age and length at first maturation, and lifespan, while CWM of growth rate showing a declining trend. This study provides a necessary empirical assessment of the efficiency of a fishing ban in restoring fisheries resources in freshwater ecosystems. Furthermore, single-trait-based functional diversity is a useful tool to detect early fish community changes, enabling a robust evaluation of conservation outcomes.

Understanding spatial variation of species composition at different scales is essential for efficient conservation planning. Here, we investigate ecological uniqueness patterns of freshwater macrophyte assemblages at continental extents. We explored the similarities and differences in the patterns of ecological uniqueness between Europe and North America in relation to species richness and environmental variables using macrophyte presence–absence data in 50 × 50 km grid cells. To describe the ecological uniqueness of macrophyte assemblages, we used an index called ‘local contribution to beta diversity’ (LCBD). First, we used linear regression to evaluate the relationship between ecological uniqueness and species richness. Second, the variation of ecological uniqueness was modelled using environmental variables in generalized additive modelling (GAM). Third, boosted regression tree (BRT) analysis was performed with the same environmental variables to compare BRT results with the results from GAM. The results revealed relatively similar patterns of ecological uniqueness in both continents. The relationship between species richness and ecological uniqueness was overall negative but showed differences in the form and degree of the relationship between Europe and North America. The main driver of ecological uniqueness in both continents was mean annual temperature, with further effects associated with annual precipitation, elevation range, alkalinity and the proportion of freshwaters in a grid cell. Synthesis. Our results showed that species richness and ecological uniqueness may be negatively correlated at large spatial extents, and that the form of the relationship is likely to depend on the species richness profile of the area. The significant influence of climate on the ecological uniqueness of macrophyte assemblages suggests that changes in climate and land use may shape unique macrophyte assemblages. Thus, conservation strategies should consider protection measures, especially in the northern areas with unique macrophyte species assemblages, as they are expected to face many changes in the future. Identifying areas with high ecological uniqueness at different scales is important for efficient implementation of biodiversity conservation practices.

Measures based on functional traits are often capable of indicating local environmental conditions and are thus considered promising tools for environmental monitoring and assessment programs. Benthic macroinvertebrates exhibit a diverse array of functional traits that can be used for assessing ecological quality of freshwater ecosystems. However, the associations between functional structure of macroinvertebrates and anthropogenic disturbances remain inadequately understood, especially for floodplain lakes. In our study, we compared the response of taxonomic and functional trait composition of macroinvertebrates to anthropogenic eutrophication in lake ecosystems of the Yangtze River floodplain. We found that the relative abundance of Mollusca, Gastropods, Bithyniidae, Bivalvia and Ephemeroptera showed significant differences among four lake groups (river-connected, macrophyte-dominated, macrophyte-algal transitional and algal-dominated lakes) subjected to different disturbance levels from mesotrophic to highly eutrophic. Using a trait-based approach, we found 13 categories, belonging to seven traits, showed significant differences observed among lake groups. Regarding influence of environmental factors on macroinvertebrate assemblages, both taxonomic measures and functional traits were mainly affected by water quality factors associated with eutrophication. However, the number and specific key environmental factors varied between measures of functional traits and taxonomic composition. The taxonomic composition responded to more environmental factors (seven factors: Chl a, CODmn, TN, area, water depth, NH4⁺-N and conductivity), but showed lower explained variation (24.4%) compared with functional structure (three factors: aquatic vegetation coverage, conductivity and Chl a, 36.4% explained variation). Furthermore, spatial factors only affected taxonomic composition, but they were not correlated with functional composition. In general, our study showed that functional trait structure of macroinvertebrate assemblages responded more sensitively and reliably to eutrophication than measures based on taxonomic composition in floodplain lakes. Thus, we recommend the incorporation of macroinvertebrate functional trait information into biomonitoring programs for floodplain lakes and other aquatic ecosystems, as it can be considered as a more promising approach than taxonomy-based approaches in biomonitoring programs.

Biodiversity loss is increasing worldwide, necessitating effective approaches to counteract negative trends. Here, we assessed aquatic macroinvertebrate biodiversity in two river catchments in Switzerland; one significantly degraded and associated with urbanisation and instream barriers, and one in a near-natural condition. Contrary to our expectations, environmental heterogeneity was lower in the near-natural stream, with enhanced productivity in the degraded system resulting in a greater range of environmental conditions. At face value, commonly employed alpha, beta and gamma biodiversity metrics suggested both catchments constituted healthy systems, with greater richness or comparable values recorded in the degraded system relative to the near-natural one. Further, functional metrics considered to be early indicators for anthropogenic disturbance, demonstrated no anticipated differences between degraded and near-natural catchments. However, investigating the identity of the taxa unique to each river system showed that anthropogenic degradation led to replacement of specialist, sensitive species indicative of pristine rivers, by generalist, pollution tolerant species. These replacements reflect a major alteration in community composition in the degraded system compared with the near-natural system. Total nitrogen and fine sediment were important in distinguishing the respective communities. We urge caution in biodiversity studies that employ numerical biodiversity metrics alone. Assessing just one aspect of diversity, such as richness, is not sufficient to track biodiversity changes associated with environmental stress. We advocate that biodiversity monitoring for conservation and management purposes must go beyond traditional richness biodiversity metrics, to include indices that incorporate detailed nuances of biotic communities that relates to taxon identity. Supplementary Information The online version contains supplementary material available at 10.1007/s10531-024-02933-7.

1. Revealing the mechanisms underlying community organization has long been a central interest for ecologists and biogeographers. Recent findings have suggested that different dimensions of biodiversity may be shaped by contrasting ecological processes, offering complementary insights about community assembly. However, evaluations integrating multiple diversity facets across the Qinghai-Tibetan Plateau (QTP) remain underdeveloped. 2. We combined multiple analytical frameworks to unravel the patterns (taxonomic, functional and phylogenetic) and correlates (local environment, land use and dispersal pathways) of aquatic arthropod communities in lotic and lentic ecosystems of the QTP. 3. We observed strong phylogenetic signals in most functional traits, pointing to the influence of evolutionary processes on these faunas. 4. Null models indicated that community structure in most streams and wetlands was mostly the result of random draws from the regional functional and phylogenetic species pool. The prevalence of stochasticity was most likely associated with the interplay of the paleogeographical history, the extremely harsh environmental conditions at high elevations and the subsequent impoverishment of the regional species pool. 5. However, some streams and wetlands also exhibited phylogenetic overdispersion and functional clustering, emphasizing the potential importance of competitive exclusion and habitat filtering, respectively. 6. Variation partitioning further revealed that both environmental filtering and dispersal limitation accounted for the spatial variation of diversity measures, with local environment overriding the effects of space and catchment land use. 7. Overall, this study improves our understanding of community organization and diversity patterns in environmentally extreme alpine catchments, with broad implications for the conservation and management of the world’s most relevant high-altitude treasure.

Hydrology and water quality drive multiple biological indicators in a dam-modified large river, Water Research X (2024), doi: https://doi. 1 Highlights  Freshwater biodiversity responses to multiple stressors were studied.  Hydrology and water quality primarily drove all individual biodiversity indices.  Fish and phytoplankton showed greater responses to studied stressors.  Natural, land use, and hydrological factors affected integrated indices indirectly.  Individual and integrated indices are needed for conservation and management. Abstract Freshwater biodiversity is increasingly threatened by dams and many other anthropogenic stressors, yet our understanding of the complex responses of different biotas and their multiple facets remains limited. Here, we present a multi-faceted and integrated-indices approach to assess the differential responses of freshwater biodiversity to multiple stressors in the Yangtze River, the third longest and most dam-densely river in the world. By combining individual biodiversity indices of phytoplankton, zooplankton, periphyton, macroinvertebrates, and fish with a novel integrated aquatic biodiversity index (IABI), we disentangled the effects of hydrology, water quality, land use, and natural factors on both α and β diversity facets in taxonomic, functional, and phylogenetic dimensions. Our results revealed that phytoplankton and fish species and functional richness increased longitudinally, while 4 fish taxonomic and phylogenetic β diversity increased but phytoplankton and macroinvertebrate β diversity remained unchanged. Hydrology and water quality emerged as the key drivers of all individual biodiversity indices, followed by land use and natural factors, with fish and phytoplankton showed the strongest responses. Importantly, we found that natural, land use, and hydrological factors indirectly affected biodiversity by altering water quality, which in turn directly influenced taxonomic and phylogenetic IABIs. Our findings highlight the complex interplay of multiple stressors in shaping freshwater biodiversity and underscore the importance of considering both individual and integrated indices for effective conservation and management. We propose that our multi-faceted and integrated-indices approach can be applied to other large, dam-modified river basins globally.

Functional traits are promising features for biomonitoring in freshwater ecosystems. Here, we focused on 23 floodplain lakes to evaluate the responses of taxonomic and functional traits of freshwater mollusks to the loss of lateral hydrological connectivity (LHC). Our results revealed that the disconnected lakes (DLs) had significantly lower species richness of most functional trait categories of mollusks compared to the connected lakes (CLs). For percentages of species richness, only percentages of burrowers and thick-shelled species were significantly lower in DLs than CLs, while percentages of thin-shelled and small-sized species were higher in DLs. Therefore, there has been a shift toward assemblages with thin-shelled and small mollusks following LHC loss. We also found that key environmental variables affecting taxonomic and functional composition were connectivity, lake area, aquatic vegetable coverage, and water quality. Moreover, the functional composition of all Mollusca, Gastropoda, and Bivalvia were all better explained (explained variation ranged from 0.462 to 0.684) by environmental factors compacted with taxonomic composition (0.213–0.401). Connectivity was the most important factor affecting functional trait composition, whereas area was the most important variable for taxonomic composition. Thus, the trait-based approach based on mollusks was more sensitive in assessing the impacts of disconnection than the taxonomy-based approach.