Henn Ojaveer

Henn Ojaveer
University of Tartu · Pärnu College

PhD

About

202
Publications
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Publications

Publications (202)
Article
Full-text available
Recent global trade disruptions, due to blockage of the Suez Canal and cascading effects of COVID-19, have altered the movement patterns of commercial ships and may increase worldwide invasions of marine non-indigenous species. Organisms settle on the hulls and underwater surfaces of vessels and can accumulate rapidly, especially when vessels remai...
Article
Full-text available
Native to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes and the Baltic Sea. The species is capable of reaching very high densities in the invaded ecosystems, with not only evidence for significant food-web effects on the native biot...
Article
Full-text available
Food webs are central entities mediating processes and external pressures in marine ecosystems. They are essential to understand and predict ecosystem dynamics and provision of ecosystem services. Paradoxically, utilization of food web knowledge in marine environmental conservation and resource management is limited. To better understand the use of...
Article
Full-text available
The ocean provides essential services to human wellbeing through climate regulation, provision of food, energy and livelihoods, protection of communities and nurturing of social and cultural values. Yet despite the ocean’s key role for all life, it is failing as a result of unsustainable human practices. The first global integrated assessment of th...
Article
Scientific interest in the dynamics of fish recruitment dates back to the beginning of the 20th century. Since then, several studies have shown that the environment may have a stronger effect on recruitment (R) compared to that of the spawning stock biomass (SSB). By combining a suite of methods designed to detect the non-linear, non-stationary and...
Article
Full-text available
The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment area...
Chapter
Full-text available
KEYNOTE POINTS 1. Understanding of the ocean continues to improve. Innovations in sensors andautonomous observation platforms have substantially increased observations of the ocean. Regional observation programmes have expanded, with better coordination and integration. 2. Some responses for mitigating or reducing pressures and their associated...
Chapter
Full-text available
KEYNOTE POINTS 1. Innovations in technology and engineering regarding sensors and autonomous observation platforms have substantially increased observations of the ocean and allowed for those observations to be collected at finer temporal and spatial resolutions. 2.The networking and coordination of regional observation programmes has been promote...
Chapter
Full-text available
KEYNOTE POINTS 1. The purpose of the second World Ocean Assessment is to update the first World Ocean Assessment by providing an understanding of changes that have occurred in the global ocean since 2010 and associated trends. 2. The Assessment also provides an overview of understanding of some aspects not fully covered in the first Assessment, s...
Article
The introduction of non-indigenous species (NIS) is a major driver for global change in species biogeography, often associated with significant consequences for recipient ecosystems and services they provide for humans. Despite mandated by several high-level international legislative instruments, comprehensive quantitative evaluation on ecosystem i...
Chapter
Full-text available
- The Mobilization of existing data and the development of tools and open, global repositories provide a global picture of the diversity of marine fishes, with 17762 known species, including 238 species described since the first World Ocean Assessment (United Nations, 2017) - While knowledge of the biodiversity of marine fishes exceeds that of many...
Article
Full-text available
Studying how food web structure and function varies through time represents an opportunity to better comprehend and anticipate ecosystem changes. Yet, temporal studies of highly resolved food web structure are scarce. With few exceptions, most temporal food web studies are either too simplified, preventing a detailed assessment of structural proper...
Article
Full-text available
Abstract Improving the health of coastal and open sea marine ecosystems represents a substantial challenge for sustainable marine resource management, since it requires balancing human benefits and impacts on the ocean. This challenge is often exacerbated by incomplete knowledge and lack of tools that measure ocean and coastal ecosystem health in a...
Article
Full-text available
Aim The introduction of aquatic non‐indigenous species (ANS) has become a major driver for global changes in species biogeography. We examined spatial patterns and temporal trends of ANS detections since 1965 to inform conservation policy and management. Location Global. Methods We assembled an extensive dataset of first records of detection of A...
Article
Quantification and attribution of the food web changes associated with the invasion of non-indigenous species in the marine realm often remain a challenge. One of the pelagic non-indigenous species of concern in the recent history of aquatic bioinvasions is the predatory cladoceran Cercopagis pengoi, which invaded the Baltic Sea in the early 1990s....
Article
Full-text available
The concept of ‘blue growth’, which aims to promote the growth of ocean economies whilst holistically managing marine socio-ecological systems, is emerging within national and international marine policy. The concept is often promoted as being novel, however, we show that, historical analogies exist which can provide insights for contemporary plann...
Article
Full-text available
To understand the restoration potential of degraded habitats, it is important to know the key processes and habitat features that allow for recovery after disturbance. As part of the EU (Horizon 2020) funded MERCES project, a group of European experts compiled and assessed current knowledge, from both past and ongoing restoration efforts, within th...
Article
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1. The disproportionately low presence of marine species in the list of invasive alien species (IAS) of Union concern of the European Union (EU) Regulation 1143/2014 does not fully acknowledge the threat they pose to the EU marine environment. 2. In this study, the first EU-scale Horizon Scanning (HS) focusing on marine alien species was performed,...
Article
Full-text available
Ecosystem-based management requires an assessment of the cumulative effects of human pressures and environmental change. The operationalization and integration of cumulative effects assessments (CEA) into decision-making processes often lacks a comprehensive and transparent framework. A risk-based CEA framework that divides a CEA in risk identifica...
Article
Full-text available
Parasites may play several critical functions in marine ecosystems, including possibly influencing introduction success or modifying the roles of non-indigenous species. Based on seasonally replicated sampling, we have investigated parasite communities and infection rates of the non-indigenous round goby Neogobius melanostomus in two localities in...
Article
The Ballast Water Management Convention adopted at the International Maritime Organization (IMO) allows exemptions from ballast water management requirements. These exemptions may be granted when a risk assessment results in an acceptable low risk scenario. IMO has adopted a guideline describing different risk assessment approaches (G7 Guidelines,...
Technical Report
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The Working Group on the Introductions and Transfers of Marine Organisms (WGITMO) has contributed several major achievements to the ICES vision, including the first ICES Viewpoint on Biofouling and its source document, two Cooperative Research Reports, and numerous pub-lications related to ToRs, and the continued population of the AquaNIS database....
Article
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Refined baseline inventories of non-indigenous species (NIS) are set per European Union Member State (MS), in the context of the Marine Strategy Framework Directive (MSFD). The inventories are based on the initial assessment of the MSFD (2012) and the updated data of the European Alien Species Information Network, in collaboration with NIS experts...
Article
The Arctic Limnocalanus macrurus is a prominent representative of large copepods which performs several essential functions in freshwater and marine ecosystems. Being a cold stenotherm species, its distribution is primarily confined to deeper water layers. Based on the long-term observations from one of the largest spatially confined natural popula...
Article
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In 2004, the United Nations (UN) General Assembly approved a Regular Process to report on the environmental, economic and social aspects of the world’s ocean. The Regular Process for Global Reporting and Assessment of the State of the Marine Environment, including Socioeconomic Aspects produced the first global integrated assessment of the marine e...
Technical Report
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Ecosystem Overviews (EOs) are central products in the ICES approach to support Ecosystem Based Management, through providing the ecoregion context, identifying main pressures, asso-ciated human activities and impacts on ecosystem state. The WKEO3 explored and discussed both stakeholder/client and expert views on the development of the EOs, and asse...
Article
Full-text available
Climate change in recent decades has been identified as a significant threat to natural environments and human wellbeing. This is because some of the contemporary changes to climate are abrupt and result in persistent changes in the state of natural systems; so called regime shifts (RS). This study aimed to detect and analyse the timing and strengt...
Data
List of used time series, their original temporal resolution and spatial extent. Below potted history for each variable with identified regime shifts as broken lines. Number at the broken line reflects the statistical significance of the particular regime shift. (PDF)
Data
A R script on how to depict a timing and relative strength of statistically significant RSs and the relatedness of time series within each system category (i.e. abiotic and biotic elements of atmospheric, terrestrial, bog, lake, river and marine systems) in terms of the timing of RSs. (PDF)
Article
Incorporating ecosystem changes from non-indigenous species (NIS) is an important task of maritime spatial planning. Maritime spatial planning requires a framework that emphasises ecological functioning in a state of dynamic change, including changes to ecosystem services from functions introduced by new NIS. Adaptable modelling toolsets should be...
Article
The BONUS symposium "Science delivery for sustainable use of the Baltic Sea living resources" held in Tallinn, Estonia, in October 2017 was an opportunity for the presentation and discussion of 107 papers that examined the state and dynamics of living resources of the Baltic Sea, and associated management challenges. The symposium included a half-d...
Article
Full-text available
There is no sign of saturation in accumulation of alien species (AS) introductions worldwide, additionally the rate of spread for some species has also been shown to be increasing. However, the challenges of gathering information on AS are recognized. Recent developments in citizen science (CS) provide an opportunity to improve data flow and knowle...
Preprint
Full-text available
The BONUS symposium "Science delivery for sustainable use of the Baltic Sea living resources" held in Tallinn, Estonia, in October 2017 was an opportunity for the presentation and discussion of 107 papers that examined the state and dynamics of living resources of the Baltic Sea, and associated management challenges. The symposium included a half-d...
Chapter
The introduction of non-native species is an important element of global change in marine ecosystems. This phenomenon is considered to be among the main direct drivers of biodiversity change, exacerbated as it is by climate change, pollution, habitat loss and other human-induced disturbances. Some edible marine non-native species have been widely d...
Article
Full-text available
The human-mediated introduction of marine non-indigenous species is a centuries-if not millennia-old phenomenon, but was only recently acknowledged as a potent driver of change in the sea. We provide a synopsis of key historical milestones for marine bioinva-sions, including timelines of (a) discovery and understanding of the invasion process, focu...
Technical Report
Full-text available
HELCOM facts sheet (also available here http://www.helcom.fi/baltic-sea-trends/environment-fact-sheets/biodiversity/abundance-and-distribution-of-round-goby/) on the abundance, distribution and impacts of the invasive round goby (Neogobius melanostomus) in the Baltic region.
Article
Full-text available
Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, unc...
Article
Historical marine ecology has shown that many exploited animal populations declined before their abundance was quantified by scientists. This situation applies for autumn-spawning herring (Clupea harengus) in the Baltic Sea. This stock used to be the dominant spawning group of herring in the early decades of the 1900s and supported several commerci...
Technical Report
Due to its unique characteristics with substantial drainage area and limited water exchange with the North Sea, considerable salinity gradient, permanent stratification as well as a combination of numerous, strong anthropogenic and climatic pressures the Baltic Sea environment is under constant stress. Considering the intensity of exploitation and...
Technical Report
Full-text available
Identification and quantification of pressure‐state links of biodiversity indicators is one of the major scientific challenges ahead. This task aimed at identifying and quantifying the pressure-state links of selected biodiversity indicators, their relevance and response to management measures. Relevant indicators have been selected based on their...
Article
Predator–prey interactions are a primary structuring force in marine foodwebs and they play an important role in the dynamics of both marine fish populations and their prey. We investigated the individual and spatial patterns in the feeding of two dominant zooplanktivorous clupeids—herring Clupea harengus membras and sprat Sprattus sprattus—in the...
Article
Full-text available
Invasive ecosystem engineers (IEE) are potentially one of the most influential types of biological invaders. They are expected to have extensive ecological impacts by altering the physical-chemical structure of ecosystems, thereby changing the rules of existence for a broad range of resident biota. To test the generality of this expectation, we use...
Technical Report
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MERCES is producing a census of European marine key habitat maps, degraded habitat maps and investigating key habitat restoration potential.
Technical Report
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The overall scope of MERCES Deliverable 1.2 is to review current knowledge regarding the major marine pressures placed upon marine ecosystems in EU waters and the mechanisms by which they impact habitats in order to determine potential restoration pathways.
Presentation
Protecting the ecological integrity of marine waters is a prime objective that has recently been explicitly acknowledged by the United Nations with the sustainable development goal SDG14, but that is challenged by the mounting pressures on marine systems. We here argue that the Baltic Sea can serve as marine time machine to study the causes and con...
Presentation
Full-text available
The powerpoint slides of my talk in BONUS 2017 Symposium in Tallinn explained the Empirical Dynamic Modelling toolbox as a way to detect causal links between observational variables. Examples presented in this talk included the long term variability in small-sized copepods and herring recruitment in Gulf of Riga (Baltic Sea). I show the R code and...
Article
Full-text available
Using molecular tools to examine Gobiidae, the second most abundant taxon in ichthyoplankton samples in the Gulf of Riga (Baltic Sea), the sand goby Pomatoschistus minutus was the most abundant taxon (82% of all individuals analysed), the common goby Pomatoschistus microps constituted 12% and the black goby Gobius niger 6%. The spatiotemporal distr...
Poster
Full-text available
We report media coverage of marine invasive species introduced into the Mediterranean Sea via the Suez Canal and the possible impact of its recent enlargement. We explored news websites in 30 countries, mainly European, using “Google news” search engine, for relevant articles. Our starting point for the search was the online publication of a letter...
Article
Full-text available
Cumulative effects assessments (CEAs) are inherently complex and seldom linked to real-world management processes • A risk-based CEA contains risk identification , risk analysis and risk evaluation, revealing the risk of exceeding thresholds • Embedding CEAs in a risk management process reduces complexity, streamlines scientific products, and incre...
Conference Paper
Full-text available
Human activities crisscross the urban and coastal fabric, and expand into the off shore and deep sea, deriving numerous associated pressures often impacting marine habitats. A main goal of the ongoing MERCES project (http://www.merces-project.eu/) is to produce a catalogue of available maps for existing activities and pressures in the European Seas...
Article
Full-text available
We investigated the feeding of the dominant small pelagic fish—herring Clupea harengus membras and three-spined stickleback Gasterosteus aculeatus—in the Gulf of Riga (Baltic Sea) in the summers of 1999–2014. The share of empty stomachs, stomach fullness and taxonomic composition of fish diet was analysed. On average, large herring had the highest...
Technical Report
The deliverable shed light on the direct and indirect food-web effects of increasing abundance and expanding ranges of certain invasive non-indigenous species on native populations and ecosystem functioning. The results support predictions about impact of invasive and non-indigenous species performed in WP3 and WP4. Focus was given on the invasive...
Poster
Full-text available
One of the main goals of MERCES project (http://www.merces-project.eu/) is to produce a census of available maps for marine habitats, along with their degradation status and restoration potential in the European Seas. To achieve this goal, we performed an extensive review and compiled a catalogue with mapping sources for (a) marine key-habitats, (b...
Article
The general positive effect of warmer winters on the abundance of small-sized zooplankton in the following spring and early summer has been reported from different parts of the Baltic Sea, but the mechanism of this link is not clear. Although causal links cannot be deduced with confidence from observational data, sufficiently detailed analyses can...