Tim C. Jennerjahn

Tim C. Jennerjahn
Leibniz Centre for Tropical Marine Research (ZMT) | ZMT · Department of Biogeochemistry and Geology

PhD

About

152
Publications
32,557
Reads
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3,840
Citations
Additional affiliations
July 2000 - present
Leibniz Centre for Tropical Marine Research (ZMT)
Position
  • Senior Researcher
January 2000 - October 2017
Leibniz Centre for Tropical Marine Research (ZMT)
Position
  • Senior Researcher
November 1989 - March 2000
University of Hamburg
Position
  • Staff Researcher

Publications

Publications (152)
Preprint
Full-text available
Citizen science has an active role in coastal and marine ecosystem monitoring, including seagrass beds. However, as yet the use of citizen science in the marine environment is limited. Moreover, there are very few studies analyzing and evaluating existing successful case studies, and the need for such work to fill vast information gaps is arguably...
Article
Full-text available
Tropical coastal ecosystems face increasingly severe environmental challenges. Promoting evidence-based management is one way to address these. In this paper, we propose a knowledge exchange framework to pro- mote the uptake of scientific evidence by policy and practice and discuss its effectiveness through on-the-ground implementation on the Chine...
Article
Evidence-informed decision-making is in increasing demand given growing pressures on marine environments. A way to facilitate this is by knowledge exchange among marine scientists and decision-makers. While many barriers are reported in the literature, there are also examples whereby research has successfully informed marine decision-making (i.e.,...
Article
Full-text available
There are several potential practical applications of paleoecological information that can provide guidance for improving peatland restoration in Indonesia, and highlight the values, roles, and applicability of paleoecology in ecological restoration.
Article
Seagrasses are considered one of the most rapidly declining ecosystems in the world. One of the main reasons for this decline is eutrophication during which anthropogenic impacts, including light deprivation and nutrient enrichment often result in cumulative stress for seagrasses. This study aims to investigate the physiological and morphological r...
Article
Full-text available
Southeast Asian peatlands, along with their various important ecosystem services, are mainly distributed in the coastal areas of Sumatra and Borneo. These ecosystems are threatened by coastal development, global warming and sea level rise (SLR). Despite receiving growing attention for their biodiversity and as massive carbon stores, there is still...
Chapter
Indonesia, with its more than 17,000 islands, is an extraordinary place on this planet. It is among the countries with the highest river fluxes of dissolved and particulate substances into the ocean, the most abundant mangrove forests, seagrass meadows and coral reefs, and the highest marine biodiversity. However, Indonesia is also vulnerable to ma...
Chapter
Paleoclimate research in Indonesia has become increasingly important with growing awareness of the critical role of this region for global climate. By reconstructing the past climate trend and variability, paleoclimate research contributes to a more reliable simulation of future Indonesian climate, which has proven difficult owing to the lack of te...
Chapter
Indonesia's rivers are of global importance in terms of their dissolved and particulate fluxes as well as in terms of the controlling natural factors and the human interventions in their catchments. The rivers of the volcanic islands of Java and Sumatra have been affected by different kinds of anthropogenic environmental transformation. While on Ja...
Chapter
Indonesian mangrove forests are of major local and global importance for ecological and economic reasons. Indonesia has both the largest area of mangrove forests and the highest mangrove deforestation rate by country. Using the mangrove-fringed Segara Anakan Lagoon on Java as a prime example, this chapter explains the ecosystem services provided by...
Article
The status and potential degradation of an ecosystem is often difficult to identify, quantify, and characterize. Multiple, concurrent drivers of degradation may interact and have cumulative and confounding effects, making mitigation and rehabilitation actions challenging to achieve. Ecosystem status assessments generally emphasize areal change (gai...
Chapter
Coastal sediments are important sites of microbial mediated biogeochemical cycling of nutrients such as carbon, nitrogen, iron, and sulfur. These nutrients are utilized as either electron donors or electron acceptors during the microbial respiration–coupled organic matter assimilation. During this process, the nutrients are either oxidized or reduc...
Chapter
The structure and functions of microbial communities in coastal sediments are influenced by various environmental factors. Being the largest sink of organic carbon, coastal sediments have a pivotal role in global carbon cycling. Sedimentary organic matter may be labile or refractory based on their biochemical composition and resultant stability. Th...
Chapter
The global cycling of nutrients in coastal waters has been changed profoundly due to natural and anthropogenic reasons. Global nutrient input is increasing and expected to increase with demand for food production and fuel. Concomitantly, this has led to an increase in nutrient transport from land to sea resulting in environmental deterioration as w...
Chapter
The structure and functions of microbial communities in coastal sediments are influenced by various environmental factors. Being the largest sink of organic carbon, coastal sediments have a pivotal role in global carbon cycling. Sedimentary organic matter may be labile or refractory based on their biochemical composition and resultant stability. Th...
Chapter
oastal microbial communities encompass a large taxonomic and metabolic diversity that is pronounced in sediments than water due to large surface area for microorganisms to attach. Use of traditional methods depending on the cultivation of microorganisms involving the viable plate count or most-probable-number techniques is a challenge. This is beca...
Chapter
The global cycling of nutrients in coastal waters has been changed profoundly due to natural and anthropogenic reasons. Global nutrient input is increasing and expected to increase with demand for food production and fuel. Concomitantly, this has led to an increase in nutrient transport from land to sea resulting in environmental deterioration as w...
Article
Peat fires in Indonesia are predominantly anthropogenic and intensified by El Niño Southern Oscillation (ENSO)-related droughts. In recent decades, peat fires, which typically occurred in degraded areas (partially/entirely deforested peatlands), released massive amounts of carbon by burning the peat swamp vegetation and peat substrate. However, it...
Article
Full-text available
The term ‘Blue Carbon’ was coined about a decade ago to highlight the important carbon sequestration capacity of coastal vegetated ecosystems. The term has paved the way for the development of programs and policies that preserve and restore these threatened coastal ecosystems for climate change mitigation. Blue carbon research has focused on quanti...
Article
Full-text available
Mangrove ecosystems store large amounts of 'Blue Carbon', in particular in the sediment. Research in the past decade has emphasized the quantitative significance of carbon storage in mangrove forests in climate change mitigation, mainly by determining carbon stocks and calculating potential CO2 emissions caused by mangrove degradation. However, whi...
Chapter
This chapter highlights the relevance of autochthonous versus allochthonous contributions to “Blue Carbon” storage in mangrove sediments. Mangrove ecosystems have gained major attention in the scientific community and the public in recent years, because they are considered a major natural carbon sink. However, uncertainties on the magnitude of this...
Chapter
Contamination of aquatic ecosystems by persistent organic pollutants (POPs) is a growing issue throughout the globe. Available reports highlight the importance of increasing population, changing lifestyles as the major reasons for such problems. The fate of these persistent compounds is less studied, even though their bioaccumulative and biocidal p...
Chapter
Coastal sediments are chemically complex with steep gradients of redox potential, pH, and substrate availability that contribute to the formation of large number of microhabitats. The structural heterogeneity of sediments allows resource partitioning, thus creating new niches and enhancing diversification into distinct ecological species. Spatial c...
Chapter
Coastal sediments are important sites of microbial mediated biogeochemical cycling of nutrients such as carbon, nitrogen, iron, and sulfur. These nutrients are utilized as either electron donors or electron acceptors during the microbial respiration–coupled organic matter assimilation. During this process, the nutrients are either oxidized or reduc...
Chapter
Coastal microbial communities encompass a large taxonomic and metabolic diversity that is pronounced in sediments than water due to large surface area for microorganisms to attach. Use of traditional methods depending on the cultivation of microorganisms involving the viable plate count or most-probable-number techniques is a challenge. This is bec...
Article
Coastal aquaculture expansion resulted in mangrove area loss and ecosystem degradation in the past decades, mainly in tropical Asia. Despite increasing environmental concerns regarding nutrient and organic matter-rich effluents, little is known on the effects on adjacent estuarine and coastal food webs. To assess the impact and fate of anthropogeni...
Article
Full-text available
Mangrove ecosystems store large amounts of 'Blue Carbon', in particular in the sediment. Research in the past decade has emphasized the quantitative significance of carbon storage in mangrove forests in climate change mitigation, mainly by determining carbon stocks and calculating potential CO2 emissions caused by mangrove degradation. However, whi...
Article
Although eutrophication is considered a major driver for global seagrass loss with aquaculture effluents being a main factor, little is known about the effect on seagrass meadows in eastern Asia and their resilience to long-term nutrient impact. Seagrass meadows impacted by land-based aquaculture since the 1990s, were visited in 2008/2009 and revis...
Article
Full-text available
Mangrove forests are found along the shorelines of more than 100 countries, and provide a wide range of ecosystem services that support the livelihoods and wellbeing of tens of millions of people. Despite their importance, loss of global mangrove area has been so substantial that twelve years ago academics warned of “a world without mangroves” [1]....
Article
Full-text available
The identification and quantification of natural carbon (C) sinks is critical to global climate change mitigation efforts. Tropical coastal wetlands are considered important in this context, yet knowledge of their dynamics and quantitative data are still scarce. In order to quantify the C accumulation rate and understand how it is influenced by lan...
Article
Mangrove forests suffer from large-scale conversion into pond aquaculture worldwide. However, rarely can the detailed development of these changes and the consequences for coastal biogeochemistry be traced back to baseline conditions. We analyzed decadal changes in mangrove forest and aquaculture pond cover of five estuaries along the east coast of...
Technical Report
Full-text available
The Leibniz Centre for Tropical Marine Research (ZMT) is Germany-wide the only research institute for the study of tropical and subtropical marine ecosystems and their services to human societies. In 2019, ZMT published the brochure Concepts, Collaborations, Common Grounds – The Impact of Our Work Beyond Research and Academia to illustrate how rese...
Article
The establishment and wellbeing of seedlings governs the spread and survival of mangrove forests. Eutrophication and global warming are major challenges endangering mangrove ecosystem integrity. How these stressors affect seedling growth is not well understood. In a mesocosm experiment we grew mangrove seedlings in temperature-controlled chambers a...
Article
The South China Sea (SCS), characterized by a large continental shelf, is located at the edge of the Asian monsoon domain. In this study, two marine sediment cores from the northern SCS (NSCS) continental slope were investigated to construct composite vegetation and precipitation isotopic composition records based on the d 13 C and dD values of pla...
Chapter
Full-text available
The coast is the interface between the land and the sea. It is characterized by a huge diversity of social-ecological systems (SES) and the interdependent interactions and outcomes between social and ecological subsystems (Ostrom, 2009). Many resources at the land-sea interface and property rights of those resources have characteristics of a common...
Article
Full-text available
Mangrove ecosystems are an important natural carbon sink that accumulate and store large amounts of organic carbon (Corg), in particular in the sediment. However, the magnitude of carbon stocks and the rate of carbon accumulation (CAR) vary geographically due to a large variation of local factors. In order to better understand the blue carbon sink...
Conference Paper
Full-text available
The Vembanad Lake is the largest estuarine system of Kerala. Six major rivers debouch into the southern part of the lake and introduce a large variety of organic as well as inorganic substances into it resulting from agricultural and municipal surface runoff. Moreover, a man-made barrier (Thannermukkom bund) separates the fresh water dominated area...
Conference Paper
Full-text available
Estuaries receive inputs from multiple sources of organic matter (OM), including allochthonous terrigenous materials exported from land by rivers and autochthonous production of algae. An accurate estimate of the sources of organic carbon in these sediments is essential in order to understand the transformation and the fate of terrestrial OM. The a...
Article
Full-text available
Abstract 1. Tropical peatlands, which provide important functions such as biodiversity provisioning and carbon (C) storage, are currently threatened by land-use conversions. Thus, conservation and restoration efforts are needed to maintain their functions. Conservation concepts aiming to separate human from ecosystems are no longer conceivable. The...
Article
Full-text available
Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these...
Data
Raw R-code for the submitted analyses. This is the provided raw code for the conducted bioinformatics analyses in R.
Data
Performance of the random forest analysis to predict the inhabitation status of the islands based on their microbial communities. Each model was run with 10001 trees. Performance of the random forest analysis to predict the inhabitation status of the islands based on their microbial communities. Each model was run with 10001 trees.
Data
List of eigenvectors of the individual water quality parameters contributing to the principal components (PC) of Fig. 3. NOx−, nitrite/nitrate; PO43−, phosphate; Si, silicate; Chl a, Chlorophyll a; DOC, dissolved organic carbon; TEP, transparent exopolymer particles.
Data
Bacterial diversity based on the inverse Simpson index at the inhabited and uninhabited island and its correlation with water quality parameters. (A+B) Bacterial diversity of the free-living fraction of the water column (>0.2 μm; FL). (C+D) Bacterial diversity of the particle-attached fraction of the water column (>3 μm; PA). (E+F) Bacterial divers...
Data
Rarefaction analysis of alpha diversity indices of bacterial communities at the inhabited and uninhabited island. Rarefaction analysis of alpha diversity indices of bacterial communities at the inhabited and uninhabited island for sequencing depths of 0 to 20,000 sequences using the R packageiNEXT. (A+B) Bacterial diversity of the free-living fract...
Data
Composition and dissimilarity of bacterial communities at the inhabited and uninhabited island. (A) Cluster diagram based on Bray-Curtis dissimilarity coefficients constructed using average linkage. (B) Class-level taxonomic composition of the bacterial communities. FL, Free-living bacterial communities of the water column (>0.2 μm); PA, Particle-a...
Data
Heatmap of centered log ratio (clr)-transformed sequence counts of OTUs best suited to differentiate bacterial communities between the inhabited and uninhabited island based on random forest analysis. Red colors indicate an enrichment of an OTU compared to the average sequence contribution of all OTUs in a sample, whereas blue colors indicate deple...
Data
Summary of the water quality parameters at the inhabited (BL: Barrang Lompo) and the uninhabited island (KK: Kodinggareng Keke). NOx−, nitrite/nitrate; PO43−, phosphate; Si, silicate; Chl a, Chlorophyll a; DOC, dissolved organic carbon; TEP, transparent exopolymer particles; N, number of replicates; SD, standard deviation; SEM, standard error of th...
Data
Heatmap of centered log ratio (clr)-transformed sequence counts of potentially pathogenic OTUs identified in the inhabited and uninhabited island based on random forest analysis. Red colors indicate an enrichment of an OTU compared to the average sequence contribution of all OTUs in a sample, whereas blue colors indicate depletion. For each OTU, it...
Data
Number of generated (raw) and quality-checked (final) sequences produced from bacterial communities of the free-living and particle-attached fraction of the water column and reef sediment at the inhabited (BL: Barrang Lompo) and the uninhabited island (KK). OTU number (nOTU) and Inverse Simpson diversity index (invS) were calculated based on the co...
Preprint
Full-text available
Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these...
Preprint
Full-text available
Water quality deterioration caused by an enrichment in inorganic and organic matter due to anthropogenic inputs is one of the major local threats to coral reefs in Indonesia. However, even though bacteria are important mediators in coral reef ecosystems, little is known about the response of individual taxa and whole bacterial communities to these...
Chapter
This chapter assesses the response of mangrove ecosystems to possible outcomes of climate change, with regard to the following categories: (i) distribution, diversity, and community composition, (ii) physiology of flora and fauna, (iii) water budget, (iv) productivity and remineralization, (v) carbon storage in biomass and sediments, and (vi) the f...
Article
Full-text available
Changes in tropical zonal atmospheric (Walker) circulation induce shifts in rainfall patterns along with devastating floods and severe droughts that dramatically impact the lives of millions of people. Historical records and observations of the Walker circulation over the 20th century disagree on the sign of change and therefore, longer climate rec...
Article
Tropical peatlands are important for the global carbon cycle as they store 18% of the total global peat carbon. As they are vulnerable to changes in temperature and precipitation, a rapidly changing environment endangers peatlands and their carbon storage potential. Understanding the mechanisms of peatland carbon accumulation from studying past dev...
Article
Mangrove leaves form a large pool of carbon, nitrogen and energy that is a major driver of element cycles and detrital food webs inside mangrove forests as well as in adjacent coastal waters. However, there are large gaps in knowledge on the transformation pathways and ultimate fate of leaf nitrogen. Therefore, the main objective of this study was...
Article
The Northern Bay of Bengal (NBoB) is a globally important region for deep-sea organic matter (OM) deposition due to massive fluvial discharge from the Ganges-Brahmaputra-Meghna (G-B-M) rivers and moderate to high surface productivity. Previous studies have focused on carbon burial in turbiditic sediments of the Bengal Fan. However, little is known...
Article
Full-text available
Holocene sequences in the humid tropical region of Kerala, South-western (SW) India have preserved abundance of organic-rich sediments in the form of peat and its rapid development in a narrow time frame towards Middle Holocene has been found to be significant. The sub-coastal areas and flood plains of the Greater Pamba Basin have provided palaeore...
Article
To obtain insight into the natural variability of the coastal ecosystems off southern Kalimantan, late Holocene environmental conditions between ca 2850 and 990 cal yr BP in the Java Sea were investigated. A 134 cm-long sediment core collected ∼50 km off the Pembuang River mouth was analyzed for organic-walled dinoflagellate cysts (dinoflagellate c...
Article
Full-text available
From the 2013 ECSA conference ‘Estuaries and Coastal Areas in Times of Intense Change’ a theme emerged that has ended up being the focus of this Special Issue of Estuarine Coastal and Shelf Science, namely ‘Changes to processes in estuaries and coastal waters due to intense multiple pressures’. Many parts of the world are continuing to experience u...
Article
Settling particles collected in a sediment trap 60 km off SW Java in the Indian Ocean at a 2200 m deep site, about 830 m above the sea floor, between December 2001 and November 2002 (intervals of 16 days for 11 months) were analyzed for the abundance and taxa composition of pollen and spores. Several factors control their deposition such as the mon...