The influence of balanced and imbalanced resource supply on biodiversity – functioning relationship across ecosystems

Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

Aquatic noise pollution: implications for individuals, populations, and ecosystems

Anthropogenically driven environmental changes affect our planet at an unprecedented scale, and are considered to be a key threat to biodiversity. According to the World Health Organisation, anthropogenic noise is one of the most hazardous forms of anthropogenically driven environmental change and is recognised as a major global pollutant. However, crucial advances in the rapidly emerging research on noise pollution focus exclusively on single aspects of noise pollution, e.g. on behaviour, physiology, terrestrial ecosystems or by focusing on certain taxa. Given that more than two thirds of our planet is covered with water, there is a pressing need to get a holistic understanding of the effects of anthropogenic noise in aquatic ecosystems. We found experimental evidence for negative effects of anthropogenic noise on an individual’s development, physiology, and/or behaviour in both invertebrates and vertebrates. We also found that species differ in their response to noise, and highlight the potential underlying mechanisms for these differences. Finally, we point out challenges in the study of aquatic noise pollution and provide directions for future research, which will enhance our understanding of this globally present pollutant.

Fingerprinting of Mangrove Ecosystems along Northern Kerala Coast using Biomarker Approach

Mangrove forests are the most productive and bio-diverse wetlands on earth. It generate a large amount of litter in the form of leaves, branches, twigs, inflorescence and other debris and provides habitat for diverse flora and fauna of marine and terrestrial origin such as bacteria, fungi, algae, lichens, zooplankton, benthos, birds, reptiles and mammals. These systems act as nursery for many fishes and shellfishes. The other sources may also provide important organic carbon inputs; including allochthonous riverine or marine material, autochthonous production by benthic or epiphytic micro- or macroalgae, and local water column production by phytoplankton. Since mangrove sediments are very complex which receives autochthonous and allochthonous organic matter inputs, the information extracted from the analysis of mangrove sediments is the fingerprint of both natural and human-induced changes.

Biomarker Geochemistry of Core Sediments in the Mangrove Ecosystems along Northern Kerala Coast

Mangroves are diverse group of trees, palms, shrubs, and ferns that share a common ability to live in waterlogged saline soils exposed to regular flooding, and are highly specialised plants which have developed unusual adaptations to the unique environmental conditions. They are sites of accumulation and preservation of both allochthonous and autochthonous organic matter owing to their strategic loction at the interface between land and sea and prevailing reducing environment. They are among the most productive ecosystems and are efficient carbon sinks with most of the carbon stored in sediments.Mangrove ecosystems play a significant role in global carbon cycle and hence the knowledge on the processes controlling the delivery of organic matter to coastal sediments, and how these signatures are preserved in the sediment is a prerequisite for the understanding of biogeochemical cycles. The evaluation of nature and sources of organic matter can be accomplished by the determination of biochemical constituents like carbohydrates, proteins and lipids. When characterised at molecular level, lipids provide valuable information about the sources of organic matter, even though they account only small fraction of organic matter. They are useful for the paleo-environmental reconstruction because of their low reactivity, high preservation potential and high source specificity relative to other organic class of compounds. The application of recent analytical techniques has produced a wealth of useful information but has also indicated the gaps in our knowledge on cycling of organic matter in the coastal ecosystems. The quantity and quality of organic matter preserved in sediments vary depending up on the nature of material delivered to the sediment and on the depositional environment. The input from both autochthonous and allochthonous sources sharpens the complexity of biogeochemistry of mangrove ecosystem and hence bulk sedimentary parameters are not completely successful in evaluating the sources of organic matter in mangrove sediments. An effective tool for the source characterisation of organic matter in coastal ecosystems is biomarker approach. Biomarkers are chemical "signatures" present in environmental samples whose structural information can be linked to its biological precursor. The usefulness of molecular biomarkers depends on high taxonomic specificity, potential for preservation, recalcitrant against geochemical changes, easily analysable in environmental samples and should have a limited number of well-defined sources.

Peat Bog Ecosystems: Peatland Restoration

Peatland restoration involves giving aid to a complex ecosystem which has been damaged in some way. A reasonable analogy is a patient brought to a hospital for urgent treatment. When arriving at Accident & Emergency , the first priority of the medical team is to stabilise the patient’s condition. Only after the patient’s condition has been assessed and then stabilised can the team begin to think about the longer - term process of healing and recovery. A similar logic is applied to peatland s . First , stabilisation is required to prevent further degradation, following which restoration can focus on the recovery of the ecosystem.

Peat Bog Ecosystems: Tracks across peatlands

Tracks have been made across peatlands for as long as human society has existed. Un - made tracks (i.e. those created simply by regular use, with no construction involved) were probably first created by grazing animals and then presumably also used by early human communities. F ind ing these increasingly impassable with regular use , human societies began to construct ' corduroy roads ' during Neolithic, Bronze and Iron Age times. These first constructed tracks were made from cut timbers ( below ) . Across Europe, ma ny examples of these corduroy roads have been found preserved in lowland bogs, perhaps most famously in the Somerset Levels and more recently at Hatfield Moors on the Humberhead Levels.

Peat Bog Ecosystems: Atmospheric pollution

Peatlands can be damaged by deposition of pollutants from the atmosphere – often termed ‘ acid rain ’ . This results from the release of sulphur and nitrogen pollutants into the atmosphere . Originally associated with the Industrial Revolution, ‘acid rain’ was first described by Robert Angus Smith, a Manchester chemist of the 1800s , whose obser vations were made in close proximity to the peatlands of the South Pennines. Sulphur dioxide (SO 2 ) pollution, which is mainly emitted from coal burning power stations, peaked in the 1970s and has since decreased by over 90% due to emission controls and ch anges in energy supply. N itrogen ous air pollutants have decreased less . N itrogen oxide (NO x ) emissions , which are mainly from vehicle s , have decreased by two thirds since their peak in 1990 , but the decrease in ammonia ( NH 3 ) emissions , which are mainly from intensive livestock farming, is much less certain and may be only about 20%.

Soil organic carbon stocks in estuarine and marine mangrove ecosystems are driven by nutrient colimitation of P and N

Mangroves play an important role in carbon sequestration, but soil organic carbon (SOC) stocks differ between marine and estuarine mangroves, suggesting differing processes and drivers of SOC accumulation. Here, we compared undegraded and degraded marine and estuarine mangroves in a regional approach across the Indonesian archipelago for their SOC stocks and evaluated possible drivers imposed by nutrient limitations along the land-to-sea gradients. SOC stocks in natural marine mangroves (271–572 Mg ha-1 m-1 were much higher than under estuarine mangroves (100–315 Mg ha-1 m-1 with a further decrease caused by degradation to 80–132 Mg ha-1 m-1. Soils differed in C/N ratio (marine: 29–64; estuarine: 9–28), δ15N (marine: 0.6 to 0.7‰; estuarine: 2.5 to 7.2‰), and plant-available P (marine: 2.3–6.3 mg kg-1; estuarine: 0.16–1.8 mg kg-1). We found N and P supply of sea-oriented mangroves primarily met by dominating symbiotic N2 fixation from air and P import from sea, while mangroves on the landward gradient increasingly covered their demand in N and P from allochthonous sources and SOM recycling. Pioneer plants favored by degradation further increased nutrient recycling from soil resulting in smaller SOC stocks in the topsoil. These processes explained the differences in SOC stocks along the land-to-sea gradient in each mangrove type as well as the SOC stock differences observed between estuarine and marine mangrove ecosystems. This first large-scale evaluation of drivers of SOC stocks under mangroves thus suggests a continuum in mangrove functioning across scales and ecotypes and additionally provides viable proxies for carbon stock estimations in PES or REDD schemes.

Fine tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems

Invasive species pose a major threat to aquatic ecosystems. Their impact can be particularly severe in tropical regions, like those in northern Australia, where >20 invasive fish species are recorded. In temperate regions, environmental DNA (eDNA) technology is gaining momentum as a tool to detect aquatic pests, but the technology's effectiveness has not been fully explored in tropical systems with their unique climatic challenges (i.e. high turbidity, temperatures and ultraviolet light). In this study, we modified conventional eDNA protocols for use in tropical environments using the invasive fish, Mozambique tilapia (Oreochromis mossambicus) as a detection model. We evaluated the effects of high water temperatures and fish density on the detection of tilapia eDNA, using filters with larger pores to facilitate filtration. Large-pore filters (20 μm) were effective in filtering turbid waters and retaining sufficient eDNA, whilst achieving filtration times of 2-3 min per 2-L sample. High water temperatures, often experienced in the tropics (23, 29, 35 °C), did not affect eDNA degradation rates, although high temperatures (35 °C) did significantly increase fish eDNA shedding rates. We established a minimum detection limit for tilapia (1 fish/0.4 megalitres/after 4 days) and found that low water flow (3.17 L/s) into ponds with high fish density (>16 fish/0.4 megalitres) did not affect eDNA detection. These results demonstrate that eDNA technology can be effectively used in tropical ecosystems to detect invasive fish species. © 2016 John Wiley & Sons Ltd.

An evaluation of surface micro- and mesoplastic pollution in pelagic ecosystems of the Western Mediterranean Sea

This study examines the distribution, abundance and characteristics of surface micro- and mesoplastic debris in the Western Mediterranean Sea. 41 samples were collected in 2011 (summer) and 2012 (summer). Results, firstly, revealed that micro- (<5mm) and mesoplastic debris were widely and uniformly distributed in this area with average concentrations of 130,000 parts/km(2) and 5700 parts/km(2), respectively. Importantly, a strong correlation between micro- and mesoplastic concentrations was identified. Secondly, a classification based on the shape and appearance of microplastics indicated the predominant presence of fragments (73 %) followed by thin films (14 %). Thirdly, the average mass ratio of microplastic to dry organic matter has been measured at 0.5, revealing a significant presence of microplastics in comparison to plankton. Finally, a correction method was applied in order to correct wind mixing effect on microplastics' vertical distribution. This data allows for a comprehensive view, for the first time, of the spatial distribution and nature of plastic debris in the Western Mediterranean Sea.