Ecological Research Program Research Articles

Lessons for collaborative research in a changing operating environment

SummaryThis Comment records the details of an unusual multipartner ecological research programme studying Temperate Highland Peat Swamps on Sandstone in the Sydney Basin‐Blue Mountains area of New South Wales. We draw lessons from the experience of designing and managing this multipartner ecological programme, which was based on a nontraditional funding source – that is an enforceable undertaking required of a coal mining company related to an occurrence at a mine site. The research programme encompassed geomorphology, ecohydrology and ecology of a number of sites. Given the currently constrained public‐good environmental research funding and pressures for both researchers and managers to find new, collaborative ways of funding and implementing research, lessons drawn from such innovative experiences may be of wider utility. In particular, lessons are drawn from the programme regarding the time required to design collaborative processes and the need for explicit programme management capacities.

Decadal variability in coastal phytoplankton community composition in a changing West Antarctic Peninsula

The coastal waters of the West Antarctic Peninsula (WAP) are associated with large phytoplankton blooms dominated by large (>20µm) diatoms however, nanoplankton (<20µm) are also an important component of the food web. The dominant nanoflagellates in the WAP are cryptomonad algae. Using a twenty-year time series collected by the Palmer Long Term Ecological Research program at the United States Palmer Research Station, we assessed long-term patterns and stability in the coastal phytoplankton communities in the WAP. There was significant interannual variability in the integrated water column chlorophyll a (chl-a) concentrations, which varied by a factor of 5 over the 20-year time series. There has been a significant positive increase in the seasonally integrated concentration of chl-a over the time series. The dominant phytoplankton were diatoms, with cryptophytes the second most abundant. Mixed flagellates also constituted a significant fraction of the chl-a but showed less interannual variability than diatoms and cryophytes. Peak phytoplankton biomass was observed in summer months, when monthly averaged wind speed was lower than in the fall and autumn. Cryptophytes were most abundant during the summer months (December-January) after the seasonal retreat of sea ice. While diatoms were observed over the full range of observed salinities 32–34.5) as well as over the full range of in situ temperatures (−1.5 to 2.5°C), the cryptophyte populations were observed in locations with lower salinity 32.5–33.75) and colder water (−1 to 1°C). Environmental factors that favored a shallower seasonal mixed layer resulted in larger diatom blooms compared to the other phytoplankton taxa. During summer with lower phytoplankton biomass, a larger proportion of the chlorophyll a was associated with cryptophytes. These results demonstrate that continued temperature changes along the West Antarctic Peninsula will result in changes in phytoplankton concentration and community composition, which has significant ramifications for the food web.

Seasonality and land cover characteristics drive aphid dynamics in an arid city

Urbanization of arid environments results in biotic communities that differ from the surrounding desert. The growth of cities has lowered biodiversity and increased abundance of generalist species, known as urbanophiles. However, the mechanisms by which specific organisms can dominate urban ecosystems remain unclear. Using an 11-year data set from the Central Arizona-Phoenix Long-Term Ecological Research program, we evaluated how aphids, an arthropod urbanophile, were affected by habitat type and seasonality in Phoenix, Arizona, USA. Twenty-five sites were selected in habitat types varying in land use and land cover characteristics. Aphids varied along a gradient of water availability and vegetation, rather than level of urbanization. Seasonal aphid abundance was the highest in the spring and lowest in the summer, a pattern that did not differ between habitat types. We developed a mathematical model parallel to our empirical study to explain how temperature may affect the temporal patterns. The analysis of our model demonstrated that although seasonal patterns were similar across habitats, slight shifts in microclimate can result in dramatic variation of population dynamics. We conclude that both land cover and climate have huge impacts on aphids and that urbanophiles are able to take advantage of favorable environmental conditions caused by urbanization.

Insiders’ perspectives on the long‐term ecological research program

Insiders’ perspectives on the long‐term ecological research program

Wolf in sheep's clothing: Model misspecification undermines tests of the neutral theory for life histories

Understanding the processes behind change in reproductive state along life‐history trajectories is a salient research program in evolutionary ecology. Two processes, state dependence and heterogeneity, can drive the dynamics of change among states. Both processes can operate simultaneously, begging the difficult question of how to tease them apart in practice. The Neutral Theory for Life Histories (NTLH) holds that the bulk of variations in life‐history trajectories is due to state dependence and is hence neutral: Once previous (breeding) state is taken into account, variations are mostly random. Lifetime reproductive success (LRS), the number of descendants produced over an individual's reproductive life span, has been used to infer support for NTLH in natura. Support stemmed from accurate prediction of the population‐level distribution of LRS with parameters estimated from a state dependence model. We show with Monte Carlo simulations that the current reliance of NTLH on LRS prediction in a null hypothesis framework easily leads to selecting a misspecified model, biased estimates and flawed inferences. Support for the NTLH can be spurious because of a systematic positive bias in estimated state dependence when heterogeneity is present in the data but ignored in the analysis. This bias can lead to spurious positive covariance between fitness components when there is in fact an underlying trade‐off. Furthermore, neutrality implied by NTLH needs a clarification because of a probable disjunction between its common understanding by evolutionary ecologists and its translation into statistical models of life‐history trajectories. Irrespective of what neutrality entails, testing hypotheses about the dynamics of change among states in life histories requires a multimodel framework because state dependence and heterogeneity can easily be mistaken for each other.

Ecosystem function in complex mountain terrain: Combining models and long‐term observations to advance process‐based understanding

AbstractAbiotic factors structure plant community composition and ecosystem function across many different spatial scales. Often, such variation is considered at regional or global scales, but here we ask whether ecosystem‐scale simulations can be used to better understand landscape‐level variation that might be particularly important in complex terrain, such as high‐elevation mountains. We performed ecosystem‐scale simulations by using the Community Land Model (CLM) version 4.5 to better understand how the increased length of growing seasons may impact carbon, water, and energy fluxes in an alpine tundra landscape. The model was forced with meteorological data and validated with observations from the Niwot Ridge Long Term Ecological Research Program site. Our results demonstrate that CLM is capable of reproducing the observed carbon, water, and energy fluxes for discrete vegetation patches across this heterogeneous ecosystem. We subsequently accelerated snowmelt and increased spring and summer air temperatures in order to simulate potential effects of climate change in this region. We found that vegetation communities that were characterized by different snow accumulation dynamics showed divergent biogeochemical responses to a longer growing season. Contrary to expectations, wet meadow ecosystems showed the strongest decreases in plant productivity under extended summer scenarios because of disruptions in hydrologic connectivity. These findings illustrate how Earth system models such as CLM can be used to generate testable hypotheses about the shifting nature of energy, water, and nutrient limitations across space and through time in heterogeneous landscapes; these hypotheses may ultimately guide further experimental work and model development.

Recovering growth and grazing rates from nonlinear dilution experiments

AbstractBiological rate measurements provide critical information for understanding key processes and modeling future states of marine ecosystems. Experimentally derived rates can be challenging to interpret when methodological assumptions are untested or potentially violated under variable natural conditions, such as the assumed linear grazing response of the dilution technique for estimating rates of phytoplankton growth and microzooplankton grazing impact. Here, we show that grazing nonlinearity can be related to the ratio of initial phytoplankton biomass to the half‐saturation parameter in the Holling II model, while not being affected by varying grazer biomass during dilution experiments. From this, we present theory to recover growth and grazing rates from multi‐treatment dilution experiments with nonlinear grazing results. We test our analyses with data collected during the California Current Ecosystem‐Long‐Term Ecological Research (CCE‐LTER) program. We show that using a linear regression in 2‐treatment dilution experiments may lead to underestimates of microzooplankton grazing rates, particularly in high‐phytoplankton‐biomass coastal regions where grazing can be saturated. Using the Holling II grazing model and a correction factor, growth and grazing rates from 2‐treatment experiments can also be estimated, as illustrated by application to Lagrangian water‐tracking studies of growth and grazing dynamics in the CCE.

Early‐life density‐dependence effects on growth and survival in subantarctic fur seals

AbstractUnderstanding the regulation of natural populations has been a long‐standing research program in ecology. Current knowledge on marine mammals and seabirds is biased toward the adult component of populations and lacking are studies investigating the juvenile component. Our goal was to estimate demographic parameters on the pre‐weaning stage of a subantarctic fur seal (Arctocephalus tropicalis) population on Amsterdam Island, suspected to be regulated by density‐dependence. The influence of abundance on growth parameters (length and weight) and survival was assessed over a study period spanning 16 years. We evidenced a negative trend in population growth rate when density increased. Density‐dependence models were favored for pup body size and mass growth. Abundance had a clear influence on body length at high population‐density, pups grew slower and were smaller at weaning than pups born in years with low population density. Abundance partly explained pup body mass variation and a weak effect was detected on pre‐weaning survival. The causal mechanisms may be increased competition for food resources between breeding females, leading to a reduction of maternal input to their pups. Our results suggested that pup favored survival over growth and the development of their diving abilities in order to withstand the extreme fasting periods that are characteristic of this fur seal population. This analysis provides significant insight of density‐dependent processes on early‐life demographic parameters of a long lived and top‐predator species, and more specifically on the pre‐weaning stage with important consequences for our understanding of individual long‐term fitness and population dynamics.

Abiotic/Biological Interactions in Coastal Marine Communities: Insights from an Alaskan Fjord

Interactions among multi-scale coastal marine ecosystem processes can be expected to play large roles in and interact with biological processes as stresses increase, potentially allowing interfering processes (including biological interactions) to become more prevalent. Retrospective analyses of intertidal (1988–1992) and subtidal (1971–2012) species compositions from a long-term ecological research program in Port Valdez, Alaska evaluated associations between benthic community structure and physical conditions to better understand interactions between regional to local processes on flora and fauna. Low salinity, habitat structure (varying from mudflats to rocky shores over a distance of <18 km), and suspended sediments contributed to intertidal community structure via elimination of predators from low-salinity prey refugia. Subtidal communities demonstrate adjustments by macrofauna to sedimentation with smaller, disturbance-tolerant fauna towards the head of the fjord as well as effects from depth-related covariates. Shared ecological processes result in comparable community trends in subtidal and intertidal habitats among subarctic and arctic fjords and similarly among coastal environments of the North Pacific. Control exerted by interactions among climatic, oceanographic, and local processes interacting with biota contributes to the direction and length of recovery from disturbance events and environmental changes. Feedbacks, mediation of recovery by additional processes, and strengths of interactions also play important roles in determining interaction outcomes. Interactions among local, regional, and global-scale processes may become critical sources of change as global ecosystem transitions through new climate states.

An approach to analysis of functional redundancy in protozoan communities for bioassessment in marine ecosystems

It is necessary to detect how much ecological redundancy or response units (RUs) exist in communities for reducing the “signal-to-noise” ratios of the observed full species data in community-based ecological research and monitoring programs. To reveal the functional redundancy in ciliated protozoan communities in marine ecosystems for both ecological research and monitoring programs, a multivariate approach (peeling procedure) was used to identify the response units to the environmental changes using a dataset of biofilm-dwelling ciliates from coastal waters of the Yellow Sea, northern China. From the full 141-species dataset, three subsets with sufficient information of the whole community (correlation coefficient >0.75) were identified as response units (RUs 1–3) at three levels of functional redundancy, which comprised 20, 26 and 27 species, respectively. These response units appeared to be interchangeable between functional equivalents on both spatial and temporal scales. In terms of relative abundance, RU1, which predominated the ciliate communities over 1-year period, and RU2, which occurred only in warm seasons (except winter) with a peak in summer, presented a decreasing trend, while RU3, which distributed all four seasons with two peaks in summer and autumn, increased with the increase of pollution level. Furthermore, high proportions of bacterivores were found in RU1 during warm seasons and represented an increase trend, while high relative abundances of algivores occurred in RUs 2 and 3 appeared to be decreasing along the pollution gradient. These results demonstrated that the ciliated protozoan assemblages have high functional redundancy in response to environmental changes in marine ecosystems.

Salinity Variability and Water Exchange in Interconnected Estuaries

A high-resolution coastal ocean model is used to investigate salinity variability and water exchange in a complex coastal system off the southern U.S. characterized by three adjacent sounds that are interconnected by a network of channels, creeks, and intertidal areas. Model results are generally highly correlated with observations from the Georgia Coastal Ecosystem Long Term Ecological Research (GCE-LTER) program, revealing a high degree of salinity variability at the Altamaha River and Doboy Sound, decreasing sharply toward Sapelo Sound. A Lagrangian particle tracking method is used to investigate local residence time and connectivity in the system. Local residence time is highly variable, increasing with distance from the Altamaha River and decreasing with river flow, revealing that discharge plays a dominant role on transport processes and estuary-shelf exchange. The Altamaha River and Doboy Sound are connected to each other in all seasons, with exchange occurring both via coastal and estuarine pathways. While particles released at the Altamaha and Doboy rarely reach Sapelo Sound, particles released at Sapelo Sound and the creeks surrounding its main channel can reach the entire estuarine system.

Supuestos epistemológicos y ontológicos presentes en la historia de la ecología

Fil: Denegri, Guillermo Maria. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biologia. Laboratorio de Zoonosis Parasitarias; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata; Argentina

Information management at the North Temperate Lakes Long-term Ecological Research site — Successful support of research in a large, diverse, and long running project

Information management has been an integral part of the research process at the North Temperate Lakes Long-term Ecological Research (NTL LTER) program for over 30years. A combination of factors has made the information management system (IMS) at NTL very successful. Significant resources have been invested in the IMS from the beginning, the Information Manager has been part of the leadership team at NTL and later in various roles at the LTER network level; the NTL IMS was a very early adopter of database systems, standardized metadata, and a data delivery system based on those metadata. This approach has made data easily accessible to NTL researchers and the broader scientific community. Data management workflows have become increasingly more automated with adoption of modern technologies as they became available, making the system efficient enough to handle core data as well as all one-time research data generated within NTL and several related projects. More than three decades of core data from eleven lakes are reused extensively as critical background information and as the limnological go-to site for many synthesis projects within and beyond LTER.The NTL IMS continues to implement new technologies for improving data management efficiency, discovery, access, integration, and synthesis. Accordingly, the functionality of the original online data access system programmed in Java and JavaServer Pages (JSP) was ported to the modern content management system, Drupal and integrated into LTER's Drupal Ecological Information Management System (DEIMS). NTL has invested in sensor technology for studying lake conditions over the long term, which necessitated a sophisticated management system tailored to high frequency data streams. Several technologies have been used at different times for automation of management, quality control and archiving of these high volume data. Near real time lake conditions can be accessed on the NTL website and smart phone Apps.Easy access to long-term and sensor data in the NTL IMS has led NTL researchers to develop new analytical methods and the publication of several R statistical packages. Recent graduate students are now employed as data scientists helping define a new career path inspired by the availability of data.The NTL project has amassed one of the world's most comprehensive long-term datasets on lakes and their surrounding landscapes. The NTL IMS facilitates the use of these data by multiple groups for research, education, and communication of science to the public.

Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER). This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR) and chlorophyll-A (CHL)from Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input.

Establishing precise estimates of abundance in patchy habitats of the marine nearshore

Exploratory investigations of optimal sampling designs are a critical component of the decision-making process in ecology where inherent natural variation can lead to erroneous conclusions if left unexamined. Pilot studies and exploratory analyses that investigate the precision of sampling regimes may reduce the chances of erroneous results and can be used to optimise processing time in larger ecological research programs. In our study, we calculated optimal precision estimates for sampling macroinvertebrates and ichthyofauna in surf-zone wrack accumulations by investigating the precision of the mean for sub-samples of seine nets and also for the number of replicate seine nets to guide future sampling regimes. We discovered that the processing time for individual seine net samples could be reduced by 50% using sub-sampling and that time to process replicate seine net samples could be reduced by 25% while maintaining acceptable precision. In future, we suggest that the use of pilot studies with similar exploratory approaches should be less of an exception and more a critical component of ecological investigations, particularly in under-studied or newly-developing areas of research. Further, these types of exploratory approaches are crucially important in a variety of extremely patchy environments where variability is likely to be high.

HIGHLAND GRASSLANDS AT THE SOUTHERN TIP OF THE ATLANTIC FOREST BIOME: MANAGEMENT OPTIONS AND CONSERVATION CHALLENGES

The natural vegetation in the highlands of the southernmost state of Brazil, Rio Grande do Sul, is characterized by extensive grasslands in mosaics with Araucaria forests, usually under cattle grazing. Plant species diversity and endemism in these grasslands is high, though poorly recognized in conservation policy and the general public, and conversion rates into other land uses are high. In this paper, we give an overview of principal biological features of grassland vegetation in the South Brazilian highland region (plant species richness and diversity) and initiate a debate on conservation possibilities and challenges. We use data from four sites of the Long-Term Ecological Research program (LTER/PELD) Campos Sulinos situated in the highland region of the state, where we explore the effects of different types of grassland management (grazing and grazing exclusion) on vegetation structure and composition. Our data give insight into high species richness on both the plot and site scale. Overall, the results indicate the importance of adequate management for the maintenance of grassland vegetation and its characteristic biological features. In theory, grazing or fire can be employed in grassland management, but specific effects of these two types of management need to be considered, as each type of management has distinct effects. We discuss the question of active nature management in conservation units and highlight the importance of research on restoration of degraded grassland areas. Even though grasslands make up the smaller portion of the South Brazilian Atlantic Forest region, their ecological uniqueness calls for specific conservation policy. Normal 0 false false false EN-US X-NONE X-NONE

Contribución del seguimiento ecológico a largo plazo a la investigación y la gestión en la plataforma LTSER-Doñana

Diaz-Delgado, R., Carro, F., Quiros, F., Osuna, A., Baena, M. 2016. Contribution from Long-Term Ecological Monitoring to research and management of Donana LTSER Platform. Ecosistemas 25(1): 09-18. Doi.: 10.7818/ECOS.2016.25-1.03 Donana, as a whole, has definitely helped to consolidate ecological monitoring and long-term research in Spain. An integrated approach, combining the efforts of managers and researchers has led to scientific contributions improving the understanding of Donana’s biodiversity and ecosystem functioning. This paper reviews the scientific contributions and management improvements provided by the implementation of a long-term ecological monitoring program and the LTER networking activities. Especially, the paper reviews the contribution of landscape-scale monitoring by remote sensing s.l., with its retrospective and multi-scale analysis capacity; the different monitoring protocols of local populations of primary consumers and their role in the Donana ecosystems; the great effort made to incorporate automatic monitoring by deploying sensors and developments adapted to harsh field conditions; the contributions of the socio-ecological approach to assess the state of conservation and environmental services of the Donana LTSER platform; and finally, the perspective from the management of the program's usefulness when it comes to decision making and the incorporation in international networks LTER. In summary, this review aims to show the different benefits achieved by the implementation of a long-term (socio-)ecological monitoring and research program in Donana.

Temporal variation in body-size spectrum of biofilm-dwelling protozoa during the colonization process in coastal waters of the Yellow Sea, northern China

As an inherent function of a community, body-size spectrum has been increasingly used as a useful indicator in global ecological research. The colonization dynamics of biofilm-dwelling protozoa with regard to body-size spectrum were studied based on a 1-month baseline survey in coastal waters of the Yellow Sea, northern China. Samples were collected at time intervals of 1, 3, 7, 10, 14, 21 and 28 days from depths of 1 and 3 m. A total of seven body-size ranks were identified based on a trait hierarchy. The individual abundance of the protozoa at each body-size rank was well fitted to the logistic model equation. The body-size spectra showed a clear shift in probability density during the colonization period at both depths. The multivariate approach demonstrated that the temporal dynamics in body-size spectra of the protozoa may be divided into initial (1 day), transitional (3–7 days) and stable (10–28 days) stages during the colonization period. These results provide useful information for ecological research and monitoring programmes using biofilm-dwelling protozoa in marine ecosystems.

Radio-transmitter attachment methods for monitoring the endangered eastern barred bandicoot (Perameles gunnii)

Radio-tracking is a key technique for monitoring threatened species during ecological research and reintroduction programs. In the case of the endangered eastern barred bandicoot (Perameles gunnii), it has not been possible to radio-track for extended periods (≥3 months) due to difficulties in reliably and safely attaching radio-transmitters. In this study we compared eight attachment methods. Transmitters weighing 1.2–28 g were either mounted with adhesive, attached to a collar or implanted into the peritoneum. Intraperitoneal transmitters were superior in terms of attachment duration, but were considered inferior overall as they could not be fitted in the field and had a very short detection range once implanted (≤50 m). Retention times for external transmitters differed greatly between methods, ranging from 1 to 102 days. One tail-mount attachment technique caused minimal adverse effects but another caused tail amputation in one animal, and both had short retention times (3–33 days). Neither of the glue-on transmitter methods resulted in substantial periods of attachment (2–30 days) and flank-mounted transmitters also caused severe skin trauma. Radio-collars were generally retained for longer periods (42–102 days) but resulted in limb entanglement when they were fitted too loosely or subconjunctival haemorrhages when they were too tight. Cable tie collars are recommended as the most suitable attachment technique for bandicoots, as when fitted correctly they cause minimal impact to individuals and permit long retention times, but precise fitting is essential.

Unveiling the Biodiversity of Deep-Sea Nematodes through Metabarcoding: Are We Ready to Bypass the Classical Taxonomy?

Nematodes inhabiting benthic deep-sea ecosystems account for >90% of the total metazoan abundances and they have been hypothesised to be hyper-diverse, but their biodiversity is still largely unknown. Metabarcoding could facilitate the census of biodiversity, especially for those tiny metazoans for which morphological identification is difficult. We compared, for the first time, different DNA extraction procedures based on the use of two commercial kits and a previously published laboratory protocol and tested their suitability for sequencing analyses of 18S rDNA of marine nematodes. We also investigated the reliability of Roche 454 sequencing analyses for assessing the biodiversity of deep-sea nematode assemblages previously morphologically identified. Finally, intra-genomic variation in 18S rRNA gene repeats was investigated by Illumina MiSeq in different deep-sea nematode morphospecies to assess the influence of polymorphisms on nematode biodiversity estimates. Our results indicate that the two commercial kits should be preferred for the molecular analysis of biodiversity of deep-sea nematodes since they consistently provide amplifiable DNA suitable for sequencing. We report that the morphological identification of deep-sea nematodes matches the results obtained by metabarcoding analysis only at the order-family level and that a large portion of Operational Clustered Taxonomic Units (OCTUs) was not assigned. We also show that independently from the cut-off criteria and bioinformatic pipelines used, the number of OCTUs largely exceeds the number of individuals and that 18S rRNA gene of different morpho-species of nematodes displayed intra-genomic polymorphisms. Our results indicate that metabarcoding is an important tool to explore the diversity of deep-sea nematodes, but still fails in identifying most of the species due to limited number of sequences deposited in the public databases, and in providing quantitative data on the species encountered. These aspects should be carefully taken into account before using metabarcoding in quantitative ecological research and monitoring programmes of marine biodiversity.