Integrated Information System (NIOZ)
Not a member yet
5384 research outputs found
Sort by
From physics to fish: 50 years of research at Great Meteor Seamount, NE Atlantic
No full textSeamounts are among the most common physiographic systems in the global deep ocean, defining habitat for a hugely diverse biome. Great Meteor Seamount is located in the subtropical Northeast Atlantic and is considered one of the largest seamounts worldwide. Despite its remoteness, it remains one of the few seamounts globally with a long research history dating back more than 50 years. In this study, we aim to review the recent history of scientific research at Great Meteor Seamount, integrating multidisciplinary datasets of the entire seamount ecosystem, including data on plankton, benthos, fishes, and physical oceanography. The interaction of the seamount topography with background low-frequency and tidal currents creates a unique dynamical response due to its location at the critical latitude for seamount trapped diurnal waves, and the high amplitudes of semidiurnal tides. Biological observations show elevated patchiness on horizontal scales smaller than the seamount, which compares well to other seamounts with shallow summits. Regardless of ecosystem pressures associated with geographic isolation and the nutrient and organic matter deprivation inside the North Atlantic Subtropical Gyre, Great Meteor Seamount hosts a diverse species composition including megafaunal taxa such as sponges and corals, as well as species rich fish populations and meiofaunal groups of copepods and nematodes. Due to the ecological vulnerability of seamount habitats to unsustainable exploitation and their important role as open ocean hotspots of marine life, the Portuguese government plans to designate Great Meteor Seamount as a Marine Protected Area (MPA) under the European Marine Strategy Framework Directive. Here, we summarize and recount important results from the long history of research at Great Meteor Seamount in the context of present-day challenges and the initiatives to protect vulnerable ecosystems.</span
SIBES: Long-term and large-scale monitoring of intertidal macrozoobenthos and sediment in the Dutch Wadden Sea
No full textThe Wadden Sea is the world’s largest intertidal area and a UNESCO World Heritage Site. Macrozoobenthic invertebrates perform key ecological functions within intertidal areas by regulating nutrient cycles, decomposing organic matter, and providing food for fish, birds and humans. To understand ecological processes and human impacts on biodiversity, the Synoptic Intertidal BEnthic Survey (SIBES) has sampled intertidal macrozoobenthos since 2008. On average 4,109 stations across 1,200 km² of Dutch Wadden Sea mudflats are sampled from June to October to quantify the benthic invertebrate community and sediment composition, including species abundance and biomass, and grain size and mud content. The dataset published now contains 51,851 sampled stations with 3,034,760 individuals of 177 species. This paper details data collection, validation and processing methods. SIBES is ongoing and data will be updated yearly. In sharing these data, we hope to enhance collaborations and understanding of the impact of various pressures on macrozoobenthic invertebrates, sediment composition, food webs, the ecosystem, and biodiversity in the Wadden Sea and other intertidal habitats
Synthesis of population trends reveals seascape‐wide reorganisation of biodiversity from microalgae to birds
No full textMany monitoring programs aim to understand regional biodiversity patterns in relation to global and regional conservation targets, using either community-wide biodiversity metrics to describe the community status or trends of pre-selected “key” species as biodiversity change indicators. However, the former often lacks information on which species are changing, and the latter is heavily skewed towards specific taxa, potentially overlooking changes in other, functionally important taxa. We gathered an extensive set of monitoring data with over 3000 population trends (ranging from 5 to 91 years in duration) for a wide range of taxa across the Wadden Sea. We combined a systematic and quantitative categorization of population trends (weighted vote count) with a meta-analysis on different taxonomic levels. This allowed the first cross-taxa synopsis of species declines and increases and determined their directionalities throughout time. Our meta-analysis showed an overall decrease in population size for fish, zooplankton, and plant species, while birds showed an overall increase. However, these increases mask recent negative trends within specific bird groups since the late 1990s. In contrast, fish populations exhibited declines over the entire monitoring period. Species with declining populations (losers) were phylogenetically related, whereas species with increasing populations (winners) represented various organismal groups. Directionality and onsets of change in population trends were temporally synchronized throughout several groups, such as bivalves, fish, and birds, and may provide warning signals for future local extinctions in these taxa. Our analysis moves beyond typical indicator species by including the entire species inventory of the system. Basal trophic levels of aquatic ecosystems, such as zooplankton and phytoplankton, are often missing from policy assessments but are among the most important organism groups for ecosystem functioning. Here, we show that without additional monitoring effort, a systematic analysis of population trends adds to our understanding of trophic and compositional restructuring of ecosystems
Scope for waterfowl to speed up migration to a warming Arctic
No full textClimate change is causing an earlier onset of spring, requiring migratory birds to accelerate their spring migration to avoid arriving late at the breeding grounds. This acceleration hinges on the capacity to shorten the time spent building energy reserves (fuelling) for migratory flight, which is currently thought to be very limited. Combining multiyear global-positioning-system tracking and body mass data from five large-bodied Arctic-breeding waterfowl species, we demonstrate that there is considerable scope for the studied species to migrate faster by shortening the fuelling time, either before departure or at stopovers. With the exception of one species (brent goose), populations were able to largely or fully offset their spring departure date with subsequent fuelling time en route. Still, under the current rates of Arctic warming, this may allow them to mediate only a few more decades of spring advance by migrating fast
Wait a minute? Hiding behavior of burrowing crabs and an oversized bill explain why crab plovers prefer armored swimming crabs
No full textIn the Indo-West Pacific biogeographical region, a suite of shorebirds searches for crabs as food. While the majority of these shorebirds hunt on burrowing crabs, the endemic crab plover Dromas ardeola additionally feeds on swimming crabs with “fast and powerful claws”. Here, we examined the trade-off made by crab plovers between foraging for swimming crabs and burrowing crabs on the intertidal mudflats of Barr Al Hikman in the Sultanate of Oman during four winters (2012–2015). Foraging on burrowing crabs requires waiting for the occupant to emerge, whereas foraging on swimming crabs involves searching and extensive handling. We found that crab plovers strongly preferred swimming crabs. In fact, diet composition was exclusively a function of the densities of swimming crabs, that is, crab plovers stopped waiting for burrowing crabs above threshold densities of swimming crabs even if burrowing crabs were abundant. Using a two-prey functional response model, we could explain diet composition from an energy-maximization perspective, but only if waiting time was added as an identification phase independent of prey densities. This suggests that crab plovers exhibit selective attention and can only wait for a limited number of burrowing crabs at a time. We conclude that the preference for swimming crabs emerges from both the efficient handling of swimming crabs by the crab plover and the long hiding times of the burrowing crabs. Undoubtedly, it is the crab plovers\u27 specialized bill which makes handling of swimming crabs profitable. We speculate that this bill uniquely evolved in the “escalated” environment of the Indo-West Pacific.</span
Nonlinear modeling of river dunes: Insights in long-term evolution of dune dimensions and form roughness
No full textRiver dunes are large-scale (primary) bed patterns commonly occurring worldwide. Capturing these features in process-based morphodynamic models is challenging, partly because of steep gradients at the lee side of the bedform. Here, we present a new morphodynamic model with a hydrodynamic module (solved within OpenFOAM) that is capable of capturing lee side effects such as flow separation, and with a sediment transport formulation that suppresses steep lee slopes. Model results suggest that river dunes develop as free instabilities of the flat bed, characterized by initial exponential growth. After the initial phase, dunes reach a quasi-equilibrium, with the wavenumber of the dominant topographic mode decreasing over time; this holds for a range of parameter settings. Furthermore, we show that the spatially averaged water depth – a proxy for roughness – increases with about 3–5 %; the effective roughness length increases with about 50–100 %.</span
Autumn and winter plankton composition and size structure in the North Sea
No full textPlankton dynamics in temperate ecosystems have mainly been studied during productive seasons, with comparatively less research conducted during the winter, particularly on microplankton. We implemented plankton sampling during a regular fishery cruise to investigate North Sea micro- and mesozooplankton community composition, abundance, and size structure (55-2000 µm) during autumn (Buchan/Banks area) and winter (Downs area) between 2013 and 2019. Samples were analyzed using image-based techniques. Community diversity (broad taxa) was relatively similar across years in both areas, with diatoms and tripos taxa sets dominating the microplankton community and gastropods and copepods dominating the mesozooplankton group. The average micro- to mesozooplankton ratio (in abundance) was 90:1 for Buchan/Banks, resulting in an average (±SD) normalized abundance size spectra (NASS) slope of -1.45 ± 0.18. For Downs, the micro- to mesozooplankton ratio was 235:1 with a steeper NASS slope of -1.67 ± 0.20 due to fewer large organisms. Interannual changes in the planktonic community for each area and their potential environmental drivers were examined using redundancy analysis (including taxonomy and size) and correlation analysis using NASS slopes (size only). Both approaches highlighted the importance of water mass properties (e.g. salinity, temperature, turbidity) in shaping plankton dynamics, although the amount of explained variance differed between approaches (11 vs. 46%). Our results contribute to a better understanding of standing stocks of plankton and their environmental drivers. Specifically, novel insights were gained into microplankton dynamics, which play an important role in supporting the growth and survival of winter-spawned fish larvae in the North Sea.</span
Differences in bed elevation shape subtidal mussel bed stability under high‐energy hydrodynamic events
No full textEscalating high-energy hydrodynamic events, like storms, represent a significant manifestation of global climate change, causing detrimental impacts on various ecosystems and potentially triggering thresholds that result in abrupt shifts in ecosystem states. Despite the potential of such thresholds, few studies have explicitly addressed them. This gap is particularly notable for subtidal ecosystems due to technological challenges in detecting responses of organisms enduring constant submersion. This study focused on subtidal soft-bottom mussel beds through the development of Biophys loggers for in situ monitoring of the fine-scale behavior of mussel clusters under hydrodynamic disturbances and a statistical model based on an 11-yr dataset to perform regional-scale assessments of mussel bed stability. Multisite monitoring in the Dutch Wadden Sea revealed spatial heterogeneity in mussel bed mobility threshold (i.e., near-bed orbital velocity inducing mussel movement), with predictable patterns along elevation gradients. Stability assessment in this region demonstrated that mussel beds in shallower areas (i.e., at higher bed elevations) exhibited higher stability than those in deeper areas, a difference that was attributed to the longer return interval of the mobility thresholds in shallow regions. These findings suggest that conditions such as bed elevation can modulate the stress tolerance of mussels and thereby influence the stability of subtidal soft-bottom mussel beds. This study provides an approach for assessing mussel bed stability, which can also be extended to other comparable ecosystems, such as oyster reefs, to address their stability under climate change, thereby informing strategic management.</span
Mind the gap: DNA barcoding on Pachygrapsus crabs
No full textDNA barcode databases for marine invertebrates faces significant challenges, with several species revealing taxonomic issues like misidentification, ambiguity or shared barcodes. This highlights the importance of the availability of robust genetic data to resolve taxonomic uncertainties and improve species identification, which in many groups of invertebrates, like crustaceans, is lacking. Based on molecular data from the Cytochrome c oxidase I 5′ gene region (COI) for barcoding, this study highlights some of these challenges by addressing existing taxonomic ambiguities and highlighting the scarcity of genetic data for several of the shore crab genus Pachygrapsus Randall, 1840. As expected, molecular data availability is highly skewed towards taxa more prevalent in the Northern Hemisphere. Our analysis reveals a clear barcoding gap amongst Pachygrapsus species, with average interspecific p-distances of 18.75%, exceeding previously reported values for crustaceans. Furthermore, high intraspecific variation (0.70% average) suggests potential taxonomic issues, particularly within P. gracilis (de Saussure, 1857). East and west Atlantic P. gracilis populations exhibit substantial divergence (3.6% p-distance), raising the possibility of ongoing speciation due to limited gene flow across the Atlantic Ocean. Similarly, populations of P. crassipes in the east and west North Pacific exhibit substantial divergence (3.3% p-distance), which suggests possibly another speciation process. COI barcoding proves effective for species identification within Pachygrapsus and in unravelling intraspecific patterns indicative of cryptic diversity guiding further taxonomic revisions integrating morphological, genetic and ecological data.</span
Do older parents do better? Relationships between parental age, chick body condition and migratory behaviour in a colonial‐breeding waterbird
No full textAnimals\u27 performance of basic functional behaviours, such as foraging and movement, may improve with age as a result of past experiences. In migratory birds, for example, due to earlier or more efficient migration, older and likely more experienced individuals tend to arrive at breeding sites earlier and enjoy better breeding conditions than younger conspecifics, resulting in a higher reproductive success. Yet, despite the advantages of early arrival for breeding adults, the long-term effects of fledging early and/or with a higher body condition on chicks\u27 future fitness prospects remain largely unexplored. In differential migration systems, low-quality or socially subordinate individuals may be constrained to sub-optimal migratory behaviours associated with lower demographic rates. Therefore, producing high-quality chicks may enhance the survival of offspring. In this study, we analysed data from the long-term ringing programme on the breeding population of Eurasian spoonbills in the Camargue (southern France) to investigate how breeder age may influence the timing of breeding and, in turn, how this may affect chick body condition and their subsequent migratory behaviour. Using breeding resightings of birds individually marked as a chick since 2008, combined with chick biometric measurements and subsequent winter resightings of offspring, we show that older spoonbills tend to breed earlier in the season than younger individuals, and that early breeders, regardless of age, are more likely to produce chicks with higher body condition than late breeders. Finally, migratory behaviour of juveniles appears to be influenced by the timing of breeding, with later-born juveniles tending to undertake less demanding migrations (without crossing major ecological barriers) than juveniles born earlier in the breeding season. Our study therefore highlights the relevance of long-term studies to better understand the complex breeding phenology of migratory species, which can lead to changes in population-level patterns and processes.</span