Yolanda F. Wiersma

A new measure of longitudinal connectivity for stream networks

Habitat connectivity is a central factor in shaping aquatic biological communities, but few tools exist to describe and quantify this attribute at a network scale in riverine systems. Here, we develop a new index to quantify longitudinal connectivity of river networks based on the expected probability of an organism being able to move freely between two random points of the network. We apply this index to two fish life histories and evaluate the effects of the number, passability, and placement of barriers on river network connectivity through the use of simulated dendritic ecological networks. We then extend the index to a real world dendritic river system in Newfoundland, Canada. Our results indicate that connectivity in river systems, as represented by our index, is most impacted by the first few barriers added to the system. This is in contrast to terrestrial systems, which are more resilient to low levels of connectivity. The results show a curvilinear relationship between barrier passability and structural connectivity. This suggests that an incremental improvement in passability would result in a greater improvement to river network connectivity for more permeable barriers than for less permeable barriers. Our analysis of the index in simulated and real river networks also showed that barrier placement played an important role in connectivity. Not surprisingly, barriers located near the river mouth have the greatest impact on fish with diadromous life histories while those located near the center of the river network have the most impact on fish with potadromous life histories. The proposed index is conceptually simple and sufficiently flexible to deal with variations in river structure and biological communities. The index will enable researchers to account for connectivity in habitat studies and will also allow resource managers to characterize watersheds, assess cumulative impacts of multiple barriers and determine priorities for restoration.

The IQ of the Crowd: Understanding and Improving Information Quality in Structured User-Generated Content

User-generated content UGC is becoming a valuable organizational resource, as it is seen in many cases as a way to make more information available for analysis. To make effective use of UGC, it is necessary to understand information quality IQ in this setting. Traditional IQ research focuses on corporate data and views users as data consumers. However, as users with varying levels of expertise contribute information in an open setting, current conceptualizations of IQ break down. In particular, the practice of modeling information requirements in terms of fixed classes, such as an Entity-Relationship diagram or relational database tables, unnecessarily restricts the IQ of user-generated data sets. This paper defines crowd information quality crowd IQ, empirically examines implications of class-based modeling approaches for crowd IQ, and offers a path for improving crowd IQ using instance-and-attribute based modeling. To evaluate the impact of modeling decisions on IQ, we conducted three experiments. Results demonstrate that information accuracy depends on the classes used to model domains, with participants providing more accurate information when classifying phenomena at a more general level. In addition, we found greater overall accuracy when participants could provide free-form data compared to a condition in which they selected from constrained choices. We further demonstrate that, relative to attribute-based data collection, information loss occurs when class-based models are used. Our findings have significant implications for information quality, information modeling, and UGC research and practice.

Compositional diversity of rehabilitated tropical lands supports multiple ecosystem services and buffers uncertainties

High landscape diversity is assumed to increase the number and level of ecosystem services. However, the interactions between ecosystem service provision, disturbance and landscape composition are poorly understood. Here we present a novel approach to include uncertainty in the optimization of land allocation for improving the provision of multiple ecosystem services. We refer to the rehabilitation of abandoned agricultural lands in Ecuador including two types of both afforestation and pasture rehabilitation, together with a succession option. Our results show that high compositional landscape diversity supports multiple ecosystem services (multifunction effect). This implicitly provides a buffer against uncertainty. Our work shows that active integration of uncertainty is only important when optimizing single or highly correlated ecosystem services and that the multifunction effect on landscape diversity is stronger than the uncertainty effect. This is an important insight to support a land-use planning based on ecosystem services.

Evaluating the Barrier Assessment Technique Derived from FishXing Software and the Upstream Movement of Brook Trout through Road Culverts

AbstractAnthropogenic barriers to fish passage, such as culverts and dams, are major factors impeding the persistence and recovery of aquatic species. Considerable work has focused on mitigating these impacts; however, activities associated with measuring and restoring connectivity of aquatic ecosystems often face challenges in determining the passability of barriers by aquatic species. Hydrological modeling software that incorporates biological aspects of a focal species is often used as a relatively inexpensive method for assessing barrier passability for restoration decisions. However, the biological relevance of these approaches remains to be rigorously tested. We assessed passage rates of PIT-tagged Brook Trout Salvelinus fontinalis through four road culverts and adjacent reference sites (unaltered areas of the streams) on the island of Newfoundland to determine whether upstream passage through road culverts was more restrictive than unaltered reference areas of the stream. Next, we examined the usef...

Using Species Distribution Models for Conservation Planning and Ecological Forecasting

Conservation practitioners and resource managers must often work with limited data to answer critical, time-sensitive questions. In many regions of the world, even the most basic information about the distribution of species is lacking. Knowing the geographic extent of a given species or ecological system is the first step in planning for its management or conservation. The sustainable management of fish stocks, timber, waterfowl populations, and biodiversity in general requires high quality spatial data on species distributions. Selecting preserves or easements to protect plants and wildlife, for instance, requires detailed knowledge of where different species are on the landscape. Such information is the foundation of science-based management and is necessary for assessing the risks of land-use actions, management scenarios, or other human activities to plant and wildlife populations (Huettmann et al. 2005).

Investigating annual diving behaviour by hooded seals (Cystophora cristata) within the Northwest Atlantic Ocean.

With the exception of relatively brief periods when they reproduce and moult, hooded seals, Cystophora cristata, spend most of the year in the open ocean where they undergo feeding migrations to either recover or prepare for the next fasting period. Valuable insights into habitat use and diving behaviour during these periods have been obtained by attaching Satellite Relay Data Loggers (SRDLs) to 51 Northwest (NW) Atlantic hooded seals (33 females and 18 males) during ice-bound fasting periods (2004−2008). Using General Additive Models (GAMs) we describe habitat use in terms of First Passage Time (FPT) and analyse how bathymetry, seasonality and FPT influence the hooded seals’ diving behaviour described by maximum dive depth, dive duration and surface duration. Adult NW Atlantic hooded seals exhibit a change in diving activity in areas where they spend >20 h by increasing maximum dive depth, dive duration and surface duration, indicating a restricted search behaviour. We found that male and female hooded seals are spatially segregated and that diving behaviour varies between sexes in relation to habitat properties and seasonality. Migration periods are described by increased dive duration for both sexes with a peak in May, October and January. Males demonstrated an increase in dive depth and dive duration towards May (post-breeding/pre-moult) and August–October (post-moult/pre-breeding) but did not show any pronounced increase in surface duration. Females dived deepest and had the highest surface duration between December and January (post-moult/pre-breeding). Our results suggest that the smaller females may have a greater need to recover from dives than that of the larger males. Horizontal segregation could have evolved as a result of a resource partitioning strategy to avoid sexual competition or that the energy requirements of males and females are different due to different energy expenditure during fasting periods.

Drift Diving by Hooded Seals (Cystophora cristata) in the Northwest Atlantic Ocean

Many pinniped species perform a specific dive type, referred to as a ‘drift dive’, where they drift passively through the water column. This dive type has been suggested to function as a resting/sleeping or food processing dive, and can be used as an indication of feeding success by calculating the daily change in vertical drift rates over time, which reflects the relative fluctuations in buoyancy of the animal as the proportion of lipids in the body change. Northwest Atlantic hooded seals perform drift dives at regular intervals throughout their annual migration across the Northwest Atlantic Ocean. We found that the daily change in drift rate varied with geographic location and the time of year and that this differed between sexes. Positive changes in buoyancy (reflecting increased lipid stores) were evident throughout their migration range and although overlapping somewhat, they were not statistically associated with high use areas as indicated by First Passage Time (FPT). Differences in the seasonal fluctuations of buoyancy between males and females suggest that they experience a difference in patterns of energy gain and loss during winter and spring, associated with breeding. The fluctuations in buoyancy around the moulting period were similar between sexes.

Rocky shoreline protocols miss microplastics in marine debris surveys (Fogo Island, Newfoundland and Labrador)

Most anthropogenic marine debris shoreline studies are conducted on sandy shores, rather than rocky coastlines. We amended a standardized protocol for monitoring marine debris on a high-loading beach composed of small rocks and cobbles in Newfoundland, Canada. Our protocol had two parts: we conducted stratified sampling to a depth of ~20cm below the surface of the rocks (standing survey), and surveyed accumulation of items on the surface of rocks every other day (loading survey). We found the vast majority of smaller items were below the surface. Only 17.2% of debris were microplastics (<5mm). Types of anthropogenic debris differed significantly between the standing survey and the loading survey. We found no relationship between either wind direction or wind speed, and distributions of debris. This study allows for a better understanding of marine debris detection along rocky coasts, and the limitations of protocols for studying them.

Conclusion: An Attempt to Describe the State of Habitat and Species Modeling Today

We set out to deliver a book that would prompt increased attention to the ecological theory and assess the relevant assumptions that underlie predictive landscape-scale species and habitat modeling. We invited international authors who are actively engaged in advancing the discipline of predictive modeling in landscape ecology to provide chapters that would not only highlight current developments and identify outstanding gaps, but which would also reflect on how methodological choices were informed by ecological theory. In this manner, we have provided readers not with a “how-to” guide that will rapidly become outdated as methods advance, but rather insights into the thought processes, reasoning, and current debates that are common across modeling projects and methods. Such extended reflections help to show multiple viewpoints and stimulate new ideas; they rarely find space in published research manuscripts. However, we believe these will offer valuable guidance to both novice and advanced modelers seeking to discern trade-offs between alternative modeling approaches.

Variation, Use, and Misuse of Statistical Models: A Review of the Effects on the Interpretation of Research Results

The field of predictive habitat modeling evolved somewhat separately within the sub-disciplines of theoretical ecology, wildlife management, and landscape ecology. This chapter suggests that this is due to slightly different worldviews, cultures, and research applications within each subfield (Table 11.1). Within the theoretical ecology literature, models of all kinds (e.g., movement, foraging, competition, demographic) have been widespread for many years. The evolution from descriptive models of habitat quality (e.g., Whittaker and McCuen 1976), to mathematical formulations of niche (e.g., Austin 1985), to spatially-explicit predictive habitat models (e.g., Saarenmaa et al. 1988) was a gradual one. The driving force in this literature appears to be underlying theoretical formulations of a host of ecological processes and interactions (e.g., population dynamics, movement, predation, competition).