Biology subjects

Schiettekatte, N. M.

Publications and source records attributed to Schiettekatte, N. M..

5 recordsLinked to original sources

bioRxiv2026

Ubiquitous trophic niche partitioning drives species coexistence and biomass on coral reefs

Coral reefs support an extraordinary diversity and biomass of fishes. However, whether species coexist through fine-scale niche partitioning, and whether this impacts ecosystem functioning, remain unresolved. We combined DNA metabarcoding and stable isotope analysis to reconstruct a high-resolution food web and quantify the trophic niches of 2,060 reef fishes across 261 species. We observed extreme trophic partitioning: species pairs diverged by a median of 93% (DNA metabarcoding) and 86% (stable isotopes), consistently overlapping far less than expected by chance. Further, communities with greater trophic complementarity supported higher standing-stock biomass, particularly at high species richness. Our results confirm limiting similarity and trophic complementarity as the driving forces of coexistence and ecosystem functioning in the ocean's most diverse ecological community.

ecology↗

bioRxiv2026

Coral reef ecosystem functions in a human-dominated world

The metabolic processes sustaining coral reefs, from carbonate and primary production to secondary production, remain poorly integrated and rarely quantified simultaneously at global scales. This hampers our ability to predict global responses to accelerating human pressures and manage coral reef functioning. Using metabolic scaling and bioenergetic models applied to surveys from 1,100 reefs worldwide, we provide a global, standardized quantification of 14 ecosystem functions spanning benthic (corals and algae) and fish communities. Our analysis reveals a continuous functional spectrum of global coral reefs organized along four dominant axes: 1) primary production, 2) calcification and habitat structure, 3) secondary biomass production and consumption, and 4) biomass turnover. Functions mediated by fish and benthic communities show weak associations at the global scale rather than tight coupling. Climate stressors reduced calcification and local human impacts lowered secondary production. Yet these directional effects unfolded against a backdrop of substantial natural variability in reef functional configurations, such that heavily and minimally impacted reefs overlap substantially in the global functional space. Temporal analyses across three representative reef systems further revealed that functional trajectories following disturbance are context-dependent, with no universal pattern of recovery across locations. This continuous and context-dependent functional spectrum challenges the notion of universal functional benchmarks and supports locally tailored conservation strategies.

ecology↗

bioRxiv2024

Optimized recess design in artificial structures dramatically enhances coral settlement and survival

The worldwide decline of coral reefs, driven by climate change and local stressors, demands new, scalable restoration approaches. Coral larvae offer significant potential for reef recovery, as a single coral colony can release millions of offspring, with almost all larvae dying before finding a suitable habitat. Building upon an iterative design process, incorporating a gradient of sizes and angles based on larval settlement preferences observed in nature, we developed and tested seven 3D-printed settlement module designs, proposed to enhance coral larvae habitat. We studied the settlement and survival of coral larvae on the settlement modules integrating these designs and adjacent reef structures in K[a]neohe Bay over one year. Helix recesses dramatically outperformed other structural features, increasing settlement by [~]80-fold and post-settlement survival over a year by 20-50-fold compared to control modules. In contrast to natural reef substrates, settlement on modules with helix recesses increased by [~]70-fold. We identified the recess dimensions and light levels preferred as settlement habitat. In a parallel tank experiment, we explored the impacts of hydrodynamics on the settlement and survival of Montipora capitata larvae on modules with helix recesses. We found that settlement was more pronounced under high-flow conditions, suggesting a crucial role of micro-scale hydrodynamics in entraining settling corals. These findings highlight the potential of helix recesses to significantly improve early coral recruitment, a critical bottleneck in reef restoration. By integrating these structures into artificial reefs and coastal infrastructure, our approach offers an innovative, scalable, and cost-effective solution to enhance reef resilience and accelerate ecosystem recovery in a changing ocean.

ecology↗

bioRxiv2024

habtools: an R package to calculate 3D metrics for surfaces and objects

O_LITechnological advances in three-dimensional imaging techniques have opened the door to advanced morphological analyses and habitat mapping for biologists and ecologists. C_LIO_LIAt the same time, the challenge of translating complex 3D data into meaningful metrics that can be used in conjunction with biological data currently hinders progress and accessibility. C_LIO_LIWe introduce habtools, an R package that provides R functions to efficiently calculate complexity and shape metrics from DEMs, 3D meshes and 2D shapes as well as some helper functions to facilitate workflow. C_LIO_LIWe expect the functionality of habtools to continue to expand as new metrics and faster methods become available, and welcome new contributions and ideas. C_LI

ecology↗

bioRxiv2020

Global gut content data synthesis and phylogeny delineate reef fish trophic guilds

The diversity of life on our planet has produced a remarkable variety of biological traits that characterize different species. Such traits are widely employed instead of taxonomy to increase our understanding of biodiversity and ecosystem functioning. However, for species trophic niches, one of the most critical aspects of organismal ecology, a paucity of empirical information has led to inconsistent definitions of trophic guilds based on expert opinion. Using coral reef fishes as a model, we show that experts often disagree on the assignment of trophic guilds for the same species. Even when broad categories are assigned, 60% of the evaluated trait schemes disagree on the attribution of trophic categories for at least 20% of the species. This disagreement greatly hampers comparability across studies. Here, we introduce a quantitative, unbiased, and fully reproducible framework to define species trophic guilds based on empirical data. First, we synthesize data from community-wide visual gut content analysis of tropical coral reef fishes, resulting in trophic information from 13,961 individuals belonging to 615 reef fish species across all ocean basins. We then use network analysis to cluster the resulting global bipartite food web into distinct trophic guilds, resulting in eight trophic guilds, and employ a Bayesian phylogenetic model to predict trophic guilds based on phylogeny and maximum body size. Our model achieved a misclassification error of 5%, indicating that our approach results in a quantitative and reproducible trophic categorization scheme, which can be updated as new information becomes available. Although our case study is for reef fishes, the most diverse vertebrate consumer group, our approach can be applied to other organismal groups to advance reproducibility in trait-based ecology. As such, our work provides an empirical and conceptual advancement for trait-based ecology and a viable approach to monitor ecosystem functioning in our changing world.

ecology↗