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Short-term bed level changes play a critical role in long-term coastal wetland dynamics. High-frequency observation techniques are crucial for better understanding of intertidal biogeomorphic evolution. Here, we introduce an innovative instrument for bed level dynamics observation, that is, LSED-sensor (Laser based Surface Elevation Dynamics sensor). The LSED-sensors inherit the merits of the previously introduced optical SED sensors as it enables continuous high-frequency monitoring with relatively low cost of labor and acquisition. As an iteration of the optical SED-sensors, the LSED-sensors avoid touching the measuring object (i.e., bed surface), and they do not rely on daylight by adapting laser-ranging technique. Furthermore, the new LSED-sensors are equipped with a real-time data transmission function, enabling automatic observation networks covering multiple (remote) sites. During a 22-day field survey in a mangrove wetland, good agreement (R-2 = 0.7) has been obtained between the automatic LSED-sensor measurement and an accurate ground-truth measurement method, that us, Sedimentation Erosion Bars. The obtained LSED-sensor data were subsequently used to develop machine learning predictors, which revealed the effect of vegetation is a main driver in the accumulative and daily bed level changes. We expect that the LSED-sensors can further support machine learning applications to extract new knowledge on coastal biogeomorphic processes.

Assessing ‘natural’ variability of structural and functional components of ecosystems is a main target of MSFD, responding to the need of disentangling biological responses to anthropogenic stresses from those on which human impact is minimal. The scale and the extent of ecosystem components variability are main determinants of ecological patterns and process. Moreover, variability within ecosystems depends on both internal ecosystem dynamics and larger scale drivers and processes. Here we focus specifically on natural variability of biotic ecosystem components and ecosystem processes, which are either descriptors or parameters of relevance in the MSFD monitoring scheme. Metabolic theories have highlighted how the individual body size can be considered as a main, intrinsic driver of variation in populations and communities functional properties. Indeed, individual energetic and behaviour show body size dependent variation according to an x/4 rule. Cascading deterministic effects of individual level size-dependencies have been demonstrated on both population and community levels as well as on functional properties. In the presentation: i. We develop a conceptual analysis of the implication of body size dependencies of individual energetic and behaviour on scale and extent of natural variability in the individual, population and community parameters considered in the MSFD; ii. We present an example of phytoplankton parameter assessments with changing temporal scales of assessment in order to account for the natural variability of cell densities in the phytoplankton guilds; and iii. We infer from implications of biological parameter size dependencies on MSFD monitoring plan accounting for natural variability and derive operational proposals for adaptive monitoring plans.

The Marine Framework Strategy Directive (MFSD, 2008/56/EC) aims for clean, healthy and productive marine ecosystems within all the EU Members states. The MFSD promotes an holistic, ecosystem based approach to marine conservation and monitoring (Art. 13) Monitoring strategies should: 1) focus on the potential of scale dependence in the observed dynamics and 2) be able to integrate the effect of mediating factors operating at different scale levels. However, present knowledge on spatial and temporal fluctuations in marine ecosystems is scarce. The boundaries of natural variation of several important marine ecosystem processes are still undefined. A major source of complexity is the fact that ecosystem processes are occurred across different spatial as well as temporal scales. The present knowledge gap results in uncertainty on the selection of measured parameters and the definition of sampling frequency and sites. Hereby, we discuss theoretical and applied issues related to definition of optimal cross-scale monitoring strategies. Literature data and existing databases were analyzed, to define the connectivity across nested scales of principal D1 (Biodiversity), D5 (Eutrophication), D6 (Seabed habitat integrity) MFSD descriptors. We conclude that present monitoring strategy does not completely fulfil the scaling issues due to lack of theoretical knowledge on cross-scale processes and poor coordination across monitoring operators. A stronger cooperation among member states and regional environmental agencies is needed to implement efficient cross-scale environmental monitoring. This research was developed by partners of the Integrated Regional monitoring Implementation Strategy in the South European Seas (IRIS-SES, http://iris-ses.eu) Project, a pilot project on new knowledge for an integrated management of human activities in the sea (PP/ENV D2/SEA 2012), funded by the European Union.

The Marine Strategy Framework Directive (2008/56/EC) of the European Parliament and of the Council (17th June 2008) establishes a framework for community action in the field of marine environmental policy. A crucial issue will be to improve the existing marine monitoring programs to cover the MSFD requirements. The comparison and identification of gaps in the existent national monitoring is a first step to include new parameters and frequencies of observation according to all relevant Directives and specially to MSFD. Our report is a first, integrated, cross-state assessment of the present state of Mediterranean monitoring networks. Data on monitoring stations have been provided from all member states of IRIS-SES + Croatia and joint in a unique georeferenced dataset. We used the cross-classification to build contingency tables of the counts at each combination of factor levels. Distances from coastline, densities of sampling stations, spatial overlap across descriptors, were also reported. As main results, we observed a large heterogeneity across MS on the parameters measured for each descriptors, on the density of sampling stations and on the frequency of sampling. Larger gaps have been identified for the descriptors Mammals, Birds, Reptiles (D1, D4, D6), Litter (D10), Energy & Noise (D11). The outputs from this work will be included into a GIS planning tool (Activity 3) including many scales and levels on which the MSFD Directive has been built on, such as the characteristics level (e.g. biological features, physicochemical features), pressure and impact, indicator/threshold, spatial (location of monitoring stations) and temporal (frequency-periodicity) across regions-subregions-countries.

Littoral and transitional macrozoobenthic communities are characterized by a broad diversity in size and behavior. Because metabolic and geometric constraints underpin body-size scaling relationships, metabolic theory offers a useful framework to predict the numeric abundances of macrozoobenthic species. Cross Community Scaling Relationships (CCSR) expresses the relationship between the average size of an individual in an assemblage and the total number of individuals. Where resource availability or space is constant, the average amount of resource (or space) used per individual directly determines the number of individuals that can be supported. However, subsidiary factors can modulate the realized expression of metabolic/geometric scaling rules by modifying the resources accessibility/availability across the individual body size spectra. The mechanistic relevance of individual body-size on coexistence relationships still requires field and laboratory tests and community level scaling-up. Here, the influence of different physical constrains on CCSR descriptors is investigated through the analysis of a large transitional water macrozoobenthic dataset. Results show that, while the pro capite individual body size has a major role in determining the realized individual density, subsidiary physical factors can remarkably increase the accuracy of our predictions. We discuss and interpret the implications of our observations for theoretical and applied ecology.

A major source of complexity in marine ecosystem monitoring is represented by the fact that ecosystem processes occurring across different spatial and temporal scales. The implementation of the monitoring strategies applied in accordance to Marine Framework Strategy Directive (MFSD, 2008/56/EC) is a step-by-step process, which should be focus on the potential of scale dependence in the observed dynamics and should be able to integrate the effect of mediating factors operating at different scale levels. Nevertheless, the correct definition of monitoring efforts for each indicator needs to reach a well-defined knowledge on the actual assessment of the “object” of monitoring including ranges of natural variability in terms of spatial and temporal natural fluctuations. Unluckily natural fluctuations are not yet well defined in marine environments for all of the MSFD indicators. For these reasons the achievement of MSFD goals could be severely affected by the lack of knowledge which led to the lack of clear and rationale criteria on the basis of which to align and cope the scale of the assessment with the ecosystem natural fluctuations. Hereby we address the design of monitoring programmes concerning water column and seabed habitats integrity indicators (Descriptors D1, D5, D6) by discussing spatial and temporal extent of monitoring based on their scales of natural variation. The multiple layer approach developed on mesoscales could allow reducing mistakes due to sampling and methodological limits and could allow reducing problems ranging within the comprehension of mechanisms to the anticipation of consequences. The opportune mesoscale is dependent on the indicator considered and range within 0.5 – 100 km for the spatial scale and from 0.2 to 12 months for the temporal scale.

Seed burial (i.e. vertical seed dispersal) has become increasingly valued for its relevance for seed fate and plant recruitment. While ecosystem engineers have been generally considered as the most important drivers of seed burial, the role of physical forces, such as wind or water flow, has been largely overlooked. Using tidal habitats as a model system, and a combination of flume and mesocosm experiments, we investigated the effects of 1) currents, 2) benthic animals with different engineering activities and 3) their interplay on seed burial of a common salt marsh pioneer plant, Spartina anglica. Our results reveal that in such systems, water flow can be of equal or higher importance than ecosystem engineers for seed burial. For passive seed-burying engineers (PSE), coupling their actions with currents produced synergistic seed burial effects, whereas the interactive effects were only additive for active seed-burying engineers (ASE). This paper extends current understanding of seed burial and seed bank formation by revealing the need to incorporate physical forces into seed burial mechanisms. We provide the first empirical evidence that physical forces influence seed burial by synergistically interacting with ecosystem engineers, thus highlighting the role of biophysical interactions as important drivers for vertical seed movement.

Contains fulltext : 155836.pdf (Publisher’s version ) (Open Access) Radboud Universiteit Nijmegen, 12 februari 2016 Promotor : Herman, P.M.J. Co-promotores : Ysebaert, T., Bouma, T. 191 p.

Individual space and resource use are central issues in ecology and conservation. Recent technological advances such as automated tracking techniques are boosting ecological research in this field. However, the development of a robust method to track space and resource use is still challenging for at least one important ecosystem component: motile aquatic macroinvertebrates. The challenges are mostly related to the small body size and rapid movement of many macroinvertebrate species and to light scattering and wave signal interference in aquatic habitats.We developed a video tracking method designed to reliably assess space use behavior among individual aquatic macroinvertebrates under laboratory (microcosm) conditions. The approach involves the use of experimental apparatus integrating a near infrared backlight source, a Plexiglas multi‐patch maze, multiple infrared cameras, and automated video analysis. It allows detection of the position of fast‐moving (~ 3 cm/s) and translucent individuals of small size (~ 5 mm in length, ~1 mg in dry weight) on simulated resource patches distributed over an experimental microcosm (0.08 m2).To illustrate the adequacy of the proposed method, we present a case study regarding the size dependency of space use behavior in the model organism Gammarus insensibilis, focusing on individual patch selection, giving‐up times, and cumulative space used.In the case study, primary data were collected on individual body size and individual locomotory behavior, for example, mean speed, acceleration, and step length. Individual entrance and departure times were recorded for each simulated resource patch in the experimental maze. Individual giving‐up times were found to be characterized by negative size dependency, with patch departure occurring sooner in larger individuals than smaller ones, and individual cumulative space used (treated as the overall surface area of resource patches that individuals visited) was found to scale positively with body size.This approach to studying space use behavior can deepen our understanding of species coexistence, yielding insights into mechanistic models on larger spatial scales, for example, home range, with implications for ecological and evolutionary processes, as well as for the management and conservation of populations and ecosystems. Despite being specifically developed for aquatic macroinvertebrates, this method can also be applied to other small aquatic organisms such as juvenile fish and amphibians., We developed a video tracking method designed to reliably assess space use behavior among individual aquatic macroinvertebrates.To illustrate the utility of the proposed method, we present a case study regarding the size dependency of space and resource use behavior in Gammarus insensibilis, focusing on individual's patch selection, giving‐up time, and cumulative space used .We observed the negative size dependency of individual giving‐up time, showing that patch departure occurred sooner in larger individuals than smaller ones and that individual cumulative space used scaled positively with body size.

Individual energy requirements are tightly related to individual resource use and by extension of space-use patterns and other traits at higher levels of the ecological hierarchy. However, there is still little experimental evidence linking individual energetics and space-use behaviour. Individual energy requirements scale mainly with body size and temperature, but these do not explain all individual variation. Therefore, studies focused on inter individual variation in resource and space use behaviour can be used to frame foraging dynamics in an energy perspective. We empirically tested the hypothesis of a relationship between individual energetics and patch departure behaviour using as model organisms four small species (body mass ranging from 0.4 to 14 mg AFDW) of aquatic gastropods strongly differing in adult size: Galba truncatula, Bithynia tentaculata, Theodoxus fluviatilis and Ecrobia ventrosa (in descending order of size). Motility tests were performed in controlled microcosm conditions. The tests were designed to classify the specimens as either low motility (not inclined to abandon the patch) or high motility (likely to abandon the patch). The tests entailed measuring the propensity of the individuals to abandon a limited resource patch (2 g DW of conditioned Phragmites australis leaves) within a given amount of time (24 h) when foraging with conspecifics under conditions where competition for food is expected to increase over time due to resource depletion. The individual standard metabolic rate of the tested specimens was measured via open flow respirometry and compared across motility classes at intra- and interspecific level. At both levels, we observed that individuals with higher standard metabolic rates were more inclined to abandon the patch. This finding establishes a link between foraging theory and competitive coexistence mechanisms.

The present study provides energy density (ED) data and models for four macrobenthic invertebrate genera inhabiting freshwater lotic environments (Baetis, Hydropsyche, Rhyacophila, and Onychogomphus). Samples were collected in the hydrological freshwater network of the Region Friuli Venezia Giulia within different watercourse types (creeks, streams, rivers channels, and ditches), and energy density was directly measured using an adiabatic bomb calorimeter. Measured ED expressed in Joule g(-1) wet weight was strongly and positively correlated with percentage of dry weight (DW%) for all genera investigated (r(2) > 0.9504), allowing to obtain genus-specific predictive models based on the relationship between ED and DW%. Models were validated and showed good predictive power, as 90th percentile of observed percentage errors ranged between 4.23% and 5.18% while medians ranged between 1.32% and 2.83%. ANCOVA disclosed significant differences between the models, as those for Rhyacophila and Onychogomphus differed significantly from the others. The empirical models were used to build a dataset of estimated energy density, to assess the relationship between energy density and ecological status of the monitored riverine systems, assessed in compliance with European and Italian law by the application of four different ecological indices (ICMi, RQE_IBMR, STAR_ICMi, and LIMeco). Information regarding ED levels for freshwater macrobenthic invertebrates is still neglected in biomonitoring programs, but it could be useful to interpret some ecological situations in the context of ecological status assessment, especially in relation to the trophic condition of the investigated riverine systems.

According to the methodological standards established by Marine Strategy Framework Directive, the assessment for the pelagic habitat under the Biodiversity Descriptor should be carried out at the regional or sub-regional level. In the case of Mediterranean Sea, the sub-regional assessment seems optimal to take into account biogeographic differences in species composition and functional characteristics. Previous research has shown that phytoplankton diversity indicators are efficient for reliable environmental assessments, although more effort has been recommended to test these indicators on a wide spatial scale to cover wider gradients of natural and anthropogenic pressures. In this work, a set of eight diversity indices was tested against the pressure levels within a common data set of the structure and abundance of phytoplankton communities from the Adriatic, Ionian and Aegean Seas. Expert knowledge was used to define four categories of impacts that take into account partial pressures, such as point and non-point pollution, industry, ports and fisheries. At the level of the common data set, most of the diversity, evenness and dominance indices could only distinguish between the highest level of impact and the rest of impact categories. These indices maintained the distinction between two levels of subsequently dichotomised impacts (no to low impact vs. high impact) across latitudinal and longitudinal gradients. On average, the indices were less sensitive to impacts in the northernmost and westernmost areas than in the southernmost and easternmost areas, although they still showed a significant response. The results also suggest that phytoplankton communities become more uniform and less dominated by a single taxon as sampling depth increases at sites with low impact, while evenness and dominance at impacted sites remain similar at all depths. In order to establish meaningful definitions of good environmental status and targets for pelagic habitats in the Mediterranean Sea, it is necessary to establish spatially specific thresholds by additional examination of indices of good performance.

At present there is no consistent approach for the definition of Good Environmental Status (GES) and targets in the Mediterranean Sea, especially for Biodiversity Descriptors, according to the Article 12 of the Marine Strategy Framework Directive (MSFD). The use of plankton indicators in the Mediterranean Sea refers mostly to pelagic habitats in coastal waters and to case studies connected with environmental pressures, e.g. in the Adriatic, Aegean etc. The aim of this review is to study the existing biodiversity indicators for different plankton groups in order to compare GES definitions for the Biodiversity Descriptor and identify the relevant gaps and priority needs to improve coherence for the MSFD implementation across the Mediterranean. For these purposes, we focus on plankton indicators for phytoplankton, zooplankton and prokaryotes. Regional conventions (OSPAR, HELCOM, Barcelona and Bucharest Conventions) have long considered phytoplankton as a key element for integrated assessment systems. Phytoplankton biomass, community composition, abundance, frequency and intensity of blooms are used for such assessment purposes. Chlorophyll a still remains the most widely used indicator mostly thanks to its time saving, cost-effective and reproducible analytical methods that provide easily comparable datasets. Despite some integrated indices proposed for phytoplankton in the literature at the Mediterranean level, a number of constrains still prevent their wide use. Regarding zooplankton communities, commonly used indicators have a taxonomic base while recently size structure and biomass can provide a valuable index of zooplankton population dynamics and ecosystem production. Jellyfish blooms’ occurrence and frequency are also considered important zooplankton indicators in specific areas, e.g. North Adriatic. Concerning the prokaryotes, so far MSFD takes into account only their pathogenic component. The revision of MSFD GES definitions shows that all Mediterranean MSs have defined GES at the Descriptor level (e.g. D1 Biodiversity), but our comparison of approaches shows a low level of coherence in GES related to pelagic habitats and plankton communities. Gaps mostly focus on the lack of thresholds and baselines for many biodiversity indicators, and on the scarcity of common and consistent methodological approaches for biodiversity assessment by the MSs. Suggestions to fill these gaps and inconsistencies among MSs include: integration of EU legislation and Regional Agreements and Conventions; targeting on priority species and habitats; testing of existing biodiversity indices with good performances in case studies; coordination and intercalibration actions for the establishment of threshold values and baselines; determination of common methodologies; undertaking of regular monitoring programs and impact assessment studies at regional and sub-regional levels.

Behaviour related to patch resource exploitation is a major determinant of individual fitness. Assuming the size-dependency of patch departure behaviour, model-based approaches have shown size-mediated coexistence in systems of competing species. However, experimental evidence for the influence of body size on patch use behaviour is scarce. In this study, we explore whether allometric principles provide an underlying framework for interspecific patterns of resource use. To this end, we propose a meso-cosm approach using three species of gastropods differing in size as a model system and 32P radio-isotopic techniques as a measure of resource use. Foragers of different size were placed in an artificial patch, provided with a limited amount of labelled resource and let them free to move as resources decrease and scarcity is sensed. We investigated the extent to which individual body size affects the exploitation of resources by examining Giving Up Density (GUD), Giving Up Time (GUT), resource absorption rate and exploitation efficiency as components of individual exploitation behaviour. To compare positive, constant and negative individual size scaling of population energy requirements, experimental trials with an equal numbers and equal biomass of differently sized foragers were carried out, and an experimental trial with equal metabolic requirements was simulated. We observed clear size dependency in the patch departure behaviour of the experimental organisms. Even under conditions of equivalent overall population energy requirements, larger foragers decided to leave the resource patch earlier and at a higher density of resources than smaller ones. Smaller foragers were able to prolong their presence and make more use of the resources, resulting in an inverse body-size scaling of resource exploitation efficiency.