Saskia A Otto

Saskia A Otto
University of Hamburg | UHH · Institut für Hydrobiologie und Fischereiwissenschaft

PhD

About

60
Publications
13,992
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
661
Citations
Additional affiliations
March 2009 - August 2012
University of Hamburg
Position
  • PhD Student

Publications

Publications (60)
Article
Full-text available
The occurrence of regime shifts in marine ecosystems has important implications for environmental legislation that requires setting reference levels and targets of quantitative restoration outcomes. The Baltic Sea ecosystem has undergone large changes in the 20th century related to anthropogenic pressures and climate variability, which have caused...
Article
Full-text available
Seasonal Influenza A virus (IAV) infections can promote dissemination of upper respiratory tract commensals such as Streptococcus pneumoniae to the lower respiratory tract resulting in severe life-threatening pneumonia. Here, we aimed to compare innate immune responses in the lungs of healthy colonized and non-colonized mice after IAV challenge at...
Article
Full-text available
Understanding tipping point dynamics in harvested ecosystems is of crucial importance for sustainable resource management because ignoring their existence imperils social-ecological systems that depend on them. Fisheries collapses provide the best known examples for realizing tipping points with catastrophic ecological, economic and social conseque...
Article
Full-text available
Global environmental changes have accelerated at an unprecedented rate in recent decades due to human activities. As a consequence, the incidence of novel abiotic conditions and biotic communities, which have been continuously emerging in the Earth system, has rapidly risen. Despite growing attention to the incidence and challenges posed by novelty...
Article
Full-text available
Identifying key indicator species, their life cycle dynamics and the multiple driving forces they are affected by is an important step in ecosystem-based management. Similarly important is understanding how environmental changes and trophic interactions shape future trajectories of key species with potential implications for ecosystem state and ser...
Article
Full-text available
Large‐scale alterations in marine ecosystems as a response to environmental and anthropogenic pressures have been documented worldwide. Yet, these are primarily investigated by assessing abundance fluctuations of a few dominant species, which inadequately reflect ecosystem‐wide changes. In addition, it is increasingly recognized that it is not spec...
Article
Full-text available
linearity in stock-recruitment relationships of Atlantic cod: insights from a multi-model approach. The stock-recruitment relationship is the basis of any stock prediction and thus fundamental for fishery management. Traditional parametric stock-recruitment models often poorly fit empirical data, nevertheless they are still the rule in fish stock a...
Article
Full-text available
Ecosystem-based management (EBM) is commonly applied to achieve sustainable use of marine resources. For EBM, regular ecosystem-wide assessments of changes in environmental or ecological status are essential components, as well as assessments of the effects of management measures. Assessments are typically carried out using indicators. A major chal...
Article
Full-text available
Indicators are effective tools for summarizing and communicating key aspects of ecosystem state and have a long record of use in marine pollution and fisheries management. The application of biodiversity indicators to assess the status of species, habitats, and functional diversity in marine conservation and policy, however, is still developing and...
Article
Full-text available
Collapses and regime changes are pervasive in complex systems (such as marine ecosystems) governed by multiple stressors. The demise of Atlantic cod (Gadus morhua) stocks constitutes a text book example of the consequences of overexploiting marine living resources, yet the drivers of these nearly synchronous collapses are still debated. Moreover, i...
Article
Full-text available
Impermanence is an ecological principle¹ but there are times when changes occur nonlinearly as abrupt community shifts (ACSs) that transform the ecosystem state and the goods and services it provides². Here, we present a model based on niche theory³ to explain and predict ACSs at the global scale. We test our model using 14 multi-decadal time serie...
Poster
Full-text available
Overfishing and global warming are threatening the sustainability of marine social-ecological systems (SES) worldwide. In this study, we focused on the particular case of Western Baltic cod fishery which has shown a decreasing trend over the last fifteen years inducing substantial social and economic consequences. To understand the conflicts arose...
Article
Full-text available
Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional s...
Article
Full-text available
Understanding spatio-temporal dynamics of biotic communities containing large numbers of species is crucial to guide ecosystem management and conservation efforts. However, traditional approaches usually focus on studying community dynamics either in space or in time, often failing to fully account for interlinked spatio-temporal changes. In this s...
Data
Biological characteristics of species, ordered by cluster. Information about the biogeography, the trophic level (TL), the maximum length (Lmax) are from Engelhard et al., 2011. Average Catch per Unit Effort (av CPUE) are calculated from the data itself. (PDF)
Data
Full correlation coefficient table. Table of Pearson and RV correlation coefficient (c) with p-value (p) and adjusted p-value (ap). (PDF)
Data
Clustering analysis of the fish species realised with K-means algorithm. (PDF)
Data
Results of the Principal Tensor Analysis. Output of the PTA-k R-package (top) and selection of the four principal tensors (PTs) based on the scree-plot (bottom). (PDF)
Data
Robustness analysis to data transformation and spatial scale. TD computed with (A) the method presented in the manuscript (abundance expressed in number/hour, at the scale of roundfish areas), (B) abundance expressed in biomass (catch per unit effort, expressed in kg/hour) and (C) a finer spatial resolution, at the scale of ICES rectangle (and abun...
Code
INDperform is an R package for validating the performance of ecological state indicators and assessing the ecological status based on a suite of indicators. It implements a novel quantitative framework for selecting and validating the performance of state indicators tailored to meet regional conditions and specific management needs as described in...
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
Marine environmental legislation is increasingly expressing a need to consider the quality of pelagic habitats. This paper uses the European Union marine strategy framework to explore the concept of good environmental status (GES) of pelagic habitat with the aim to build a wider understanding of the issue. Pelagic ecosystems have static, persistent...
Article
Marine strategy framework directive (MSFD) Generalized additive modelling (GAM) State space approach Marine food web indicators Baltic sea Zooplankton Pelagic fish A B S T R A C T Finding suitable state indicators is challenging and cumbersome in stochastic and complex ecological systems. Typically, a great focus is given to criteria such as data a...
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...
Conference Paper
Understanding how human activities and environmental conditions shape the status of marine food webs is key for making ecosystem-based management of marine resources (EBM) operational. In the Baltic Sea, for example, significant changes in the food web during the late 1980s were caused by the combined effects of changing physical oceanographic cond...
Article
Full-text available
Transdisciplinary research that crosses disciplinary boundaries and includes stakeholder collaboration is increasingly being used to address pressing and complex socio-ecological challenges in the Anthropocene. In fisheries, we see transdisciplinary approaches being employed to address a range of challenges, including bycatch where fine-scale data...
Conference Paper
Facing implementation of the Marine Strategy Framework Directive, aiming to reach good environmental status of the marine environment, pelagic food-web indicators are crucially needed. The Baltic Sea pelagic food-web is characterized by strong trophic links between cod (Gadus morhua), and its prey sprat (Sprattus sprattus) and herring (Clupea haren...
Conference Paper
The development of MSFD indicators is particularly challenging for descriptor 4 – food-webs. Ideally, these indicators should signal the state of marine systems that are highly dynamic with complex and often non-linear interactions. Marine regions characterized by strong gradients, such as the Baltic Sea, imply additional complexity, as the relevan...
Article
Full-text available
Regime shifts are characterized by sudden, substantial and temporally persistent changes in the state of an ecosystem. They involve major biological modifications and often have important implications for exploited living resources. In this study, we examine whether regime shifts observed in 11 marine systems from two oceans and three regional seas...
Article
Full-text available
Scale is a key to determining which processes drive community structure. We analyse size distribu-tions of phytoplankton to determine time scales at which we can observe either fixed environmen-tal characteristics underlying communities structure or competition-driven size distributions. Using multiple statistical tests, we characterise size distri...
Conference Paper
Full-text available
Background / Purpose: Main environmental drivers of the seasonal life stage abundances of Pseudocalanus acuspes in combination with internal density effects were assessed to improve the understanding of its life cycle dynamics. For this, Generalized Additive Models (GAMs) were applied within a discrete stage-structured population modelling approa...
Article
Full-text available
Understanding and predicting species distribution in space and time and consequently community structure and dynamics is an important issue in ecology, and particularly in climate change research. A crucial factor determining the composition and dynamics of animal populations is habitat heterogeneity, i.e., the number of structural elements in a gi...
Article
Full-text available
Increasing pressure on animal populations through climate change and anthropogenic exploitation fuel the need for understanding complex life cycle dynamics of key ecosystem species and their responses to external factors. Here we provide a novel, integrative study on long-term population dynamics of Pseudocalanus acuspes, a key species in the Balti...
Article
Full-text available
Several marine ecosystems under anthropogenic pressure have experienced shifts from one ecological state to another. In the central Baltic Sea, the regime shift of the 1980s has been associated with food-web reorganization and redirection of energy flow pathways. These long-term dynamics from 1974 to 2006 have been simulated here using a food-web m...
Conference Paper
Background/Question/Methods The distribution of organisms along a body-size axis can reveal whether neutral or niche processes lie behind community structure: the neutral hypothesis for example predicts that such a distribution should be continuous, whereas organisms grouped in lumps can be indicative of the presence of niche-based processes. Rec...
Article
Full-text available
Critical transitions between alternative stable states have been shown to occur across an array of complex systems. While our ability to identify abrupt regime shifts in natural ecosystems has improved, detection of potential early-warning signals previous to such shifts is still very limited. Using real monitoring data of a key ecosystem component...
Data
Temporal variance of Pseudocalanus acuspes (circles) and Acartia spp. (triangles) estimated by standard deviations (SD) and the first-order autocorrelation coefficient (AR(1)) of detrended time-series for a sliding window of 10 (A, D), 15 (B, E) and 20 (C, F) years. Vertical dashed bars mark the timing of the Central Baltic Sea regime shift in the...
Data
Test results for recent trends and changes in trends over 3-year periods before the regime shift in 1988 using intersection–union tests. P-values from a χ2 goodness-of-fit test indicate whether the GAM fits satisfactory to the entire time-series. Significant negative (−) or positive (+) time trends in the rate of change (f′), as well acceleration (...
Data
Map of the Baltic Sea and its location within Northern Europe. The central part of the Baltic Sea encompasses three deep (<70 m) basins important for marine biota, the Bornholm Basin (BB), the Gdansk Deep (GD) and the Gotland Basin (GB); largely corresponding to the International Council for the Exploration of the Sea (ICES) official sub-divisions...
Data
Smoothed indicator time-series of Pseudocalanus acuspes and Acartia spp. with GAM df = 10 (A, B) and df = 20 (C, D) from 1960–1987. Bootstrapped confidence intervals are shown by grey lines. Acceleration in the rate of change (slope) in each year are shown by statistically significant second derivatives (f′′’), where black and white dots represent...
Data
The degree of spatial correlation for Pseudocalanus acuspes (A) and Acartia spp. (B) estimated as the mean significance (p-value) of spatial correlation coefficients derived from a Moran’s I test across 6 (black), 8 (grey) and 10 (black) randomly assigned stations (after 1000 resamples). Vertical dashed bars mark the timing of the Central Baltic Se...
Chapter
Full-text available
Integrated Ecosystem Assessments are an integral part of ecosystem-based management approaches and aim at describing the ecosystem and its temporal development as an entity, including environmental and anthropogenic drivers and ecosystem responses. Here, we present ecological principles and some theoretical background how ecosystems respond to chan...
Article
Natural heterogeneity in ecological parameters, like population abundance, is more widely recognized and investigated than variability in the processes that control these parameters. Experimental ecologists have focused mainly on the mean intensity of predictor variables and have largely ignored the potential to manipulate variances in processes, w...

Network

Cited By

Projects

Projects (5)
Project
balt_ADAPT will develop tools for ecosystem-based management and adaptation for the Western Baltic Sea fisheries that support policy makers in achieving a sustainable use of the fisheries resources under the effects of future climate change.