Managing Endangered Species Within the Use–Preservation Paradox: The Florida Manatee (Trichechus manatus latirostris) as a Tourism Attraction

A significant challenge to wildlife managers in tourism settings is to provide visitors with opportunities to observe rare and endangered wildlife while simultaneously protecting the target species from deleterious impacts. Nearly 100,000 people annually visit Crystal River, Florida, USA to observe and swim with the Florida manatee, an endangered species. This research aimed to investigate and describe human-manatee interactions in a tourism context, to understand the salient issues related to such interactions as identified by stakeholders, and to recommend a course of action to address multiple interests in the planning and management of human-manatee interactions. Five issues were identified by all stakeholder groups: water quality, harassment, density and crowding, education, and enforcement. Currently, the U.S. Fish and Wildlife Service, which is responsible for manatee management, does not have mechanisms in place to manage the tourism component of the manatee encounter. Although a regulatory approach can be taken, a better approach would be to create an organization of tour operators to establish "best practices" that reflect the goal of the managing agency to enhance manatee protection (and thus ensure their livelihood) and to enhance the visitor experience.     

Experimental investigation of the effect of sediment transport patterns on the adsorption of cadmium ions onto sediment particles

The mechanism of flow turbulence, sediment supply conditions, and sediment transport patterns that affect the adsorption of cadmium ions onto sediment particles in natural waters are experimentally simulated and studied in this study both in batch reactors and in a turbulence simulation tank. By changing the agitation conditions, the sediment transport in batch reactors can be categorized into bottom sediment-dominated sediment and suspended sediment-dominated sediment. It is found that the adsorption rate of bottom sediment is much less than that of suspended sediment, but the sediment transport pattern does not affect the final (equilibrium) concentration of dissolved cadmium. This result indicates that the parameters of an adsorption isotherm are the same regardless of the sediment transport pattern. In the turbulence simulation tank, the turbulence is generated by harmonic grid-stirred motions, and the turbulence intensity is quantified in terms of eddy diffusivity, which is equal to 9.84F(F is the harmonic vibration frequency) and is comparable to natural surface water conditions.When the turbulence intensity of flow is low and sediment particles stay as bottom sediment, the adsorption rate is significantly low, and the adsorption quantity compared with that of suspended sediment is negligible in the 6 h duration of the experiment. This result greatly favors the simplification of the numerical modeling of heavy metal pollutant transformation in natural rivers. When the turbulence intensity is high but bottom sediment persists, the rate and extent of descent of the dissolved cadmium concentration in the tank noticeably increase, and the time that is required to reach adsorption equilibrium also increases considerably due to the continuous exchange that occurs between the suspended sediment and the bottom sediment.A comparison of the results of the experiments in the batch reactor and those in the turbulence simulation tank reveals that the adsorption ability of the sediment, and in particular the adsorption rate, is greatly over-estimated in the batch reactor.     

Characterizing species co-occurrence patterns of imperfectly detected stream fishes to inform species reintroduction efforts

Species reintroduction efforts can improve the recovery of imperiled species, but successful implementation of this conservation strategy requires a thorough understanding of the abiotic and biotic factors influencing species viability. Species interactions are especially understudied, in particular by omitting the effect of imperfect detection on negative, neutral, or positive associations within a community. Using repeat surveys from 5 southern Ontario, Canada, Great Lakes tributaries, we quantified species co-occurrence patterns with the eastern sand darter (ESD) (Ammocrypta pellucida), listed as federally threatened, and characterized how imperfect detection during sampling can influence inference regarding these relationships. We used a probabilistic framework that included 3 approaches of increasing complexity: probabilistic co-occurrence analysis ignoring imperfect detection; single-species occupancy models with subsequent co-occurrence analysis; and 2-species occupancy models. We then used our occupancy models to predict suitable sites for potential future reintroduction efforts while considering the influence of negative species interactions. Based on the observed data, ESD showed several positive associations with co-occurring species; however, species associations differed when imperfect detection was considered. Specifically, a negative association between ESD and rosyface shiner (Notropis rubellus) was observed only after accounting for imperfect detection in the Grand River. Alternatively, positive associations in the Grand River between ESD and northern hogsucker (Hypentelium nigricans) and silver shiner (Notropis photogenis) were observed regardless of whether imperfect detection was accounted for. Our models predicted several potential reintroduction sites for ESD in formerly occupied watersheds with high levels of certainty. Overall, our results demonstrate the importance of investigating imperfect detection and species co-occurrence when planning reintroduction efforts.     

Geology-dependent impacts of forest conversion on stream fish diversity

Forest conversion is one of the greatest global threats to biodiversity, and land-use change and subsequent biodiversity declines sometimes occur over a variety of underlying geologies. However, how forest conversion and underlying geology interact to alter biodiversity is underappreciated, although spatial variability in geology is considered an integral part of sustaining ecosystems. We aimed to examine the effects of forest conversion to farmland, the underlying geology, and their interaction on the stream fishes’ diversity, evenness, and abundance in northeastern Japan. We disentangled complex pathways between abiotic and biotic factors with structural equation modeling. Species diversity of stream fishes was indirectly shaped by the interaction of land use and underlying geology. Diversity declined due to nutrient enrichment associated with farmlands, which was mainly the result of changes in evenness rather than by changes in species richness. This impact was strongest in streams with volcanic geology with coarse substrates probably because of the differential responses of abundant stream fishes to nutrient enrichment (i.e., dominance) and the high dependency of these fishes on large streambed materials during their life cycles. Our findings suggest that remediation of deforested or degraded forest landscapes would be more efficient if the interaction between land use and underlying geology was considered. For example, the negative impacts of farmland on evenness were larger in streams with volcanic geology than in other stream types, suggesting that riparian forest restoration along such streams would efficiently provide restoration benefits to stream fishes. Our results also suggest that land clearing around such streams should be avoided to conserve species evenness of stream fishes.     

Evaluating the efficacy of restoration plantings through DNA barcoding of frugivorous bird diets

Frugivores are critical components of restoration programs because they are seed dispersers. Thus, knowledge about bird–plant trophic relationships is essential in the evaluation of the efficacy of restoration processes. Traditionally, the diet of frugivores is characterized by microscopically identifying plant residues in droppings, which is time‐consuming, requires botanical knowledge, and cannot be used for fragments lacking detectable morphological characteristics (e.g., fragmented seeds and skins). We examined whether DNA barcoding can be used as a universal tool to rapidly characterize the diet of a frugivorous bird, Eurasian blackcap (Sylvia atricapilla). We used the DNA barcoding results to assess restoration efforts and monitor the diversity of potentially dispersed plants in a protected area in northern Italy. We collected 642 Eurasian Blackcap droppings at the restored site during the autumn migration over 3 years. Intact seeds and fragmented plant material were analyzed at 2 plastidial barcode loci (rbcL and trnH‐psbA), and the resulting plant identifications were validated by comparison with a reference molecular data set of local flora. At least 17 plant species, including 7 of the 11 newly transplanted taxa, were found. Our results demonstrate the potential for DNA barcoding to be used to monitor the effectiveness of restoration plantings and to obtain information about fruit consumption and dispersal of invasive or unexpected plant species. Such an approach provides valuable information that could be used to study local plant biodiversity and to survey its evolution over time.     

Redistribution of benefits but not detection in a fisheries bycatch‐reduction management initiative

Reducing the capture of small fish, discarded fish, and bycatch is a primary concern of fisheries managers who propose to maintain high yields, species diversity, and ecosystem functions. Modified fishing gear is one of the primary ways to reduce by‐catch and capture of small fish. The outcomes of gear modification may depend on c ompetition among fishers using other similar resources and other gears in the same fishing grounds and the subsequent adoption or abandonment of modified gears by fishers. We evaluated adoption of modified gear, catch size, catch per unit effort (CPUE), yield, and fisher incomes in a coral reef fishery in which a 3‐cm escape gap was introduced into traditional traps. There were 26.1 (SD 4.9) fishers who used the experimental landing sites and 228(SD 15.7) fishers who used the control landing sites annually over 7 years. The size of fish increased by 10.6% in the modified traps, but the catch of smaller fish increased by 11.2% among the other gears. There was no change in the overall CPUE, yields, or per area incomes; rather, yield benefits were redistributed in favor of the unmodified gears. For example, estimated incomes of fishers who adopted the modified traps remained unchanged but increased for net and spear fishers. Fishers using escape‐gap traps had a high proportion of income from larger fish, which may have led to a perception of benefits, high status, and no abandonment of the modified traps. The commensal rather than competitive outcome may explain the continued use of escape‐gap traps 3 years after their introduction. Trap fishers showed an interest in negotiating other management improvements, such as increased mesh sizes for nets, which could ultimately catalyze community‐level decisions and restrictions that could increase their profits.     

Meta‐Analysis of the Effects of Forest Fragmentation on Interspecific Interactions

Forest fragmentation dramatically alters species persistence and distribution and affects many ecological interactions among species. Recent studies suggest that mutualisms, such as pollination and seed dispersal, are more sensitive to the negative effects of forest fragmentation than antagonisms, such as predation or herbivory. We applied meta‐analytical techniques to evaluate this hypothesis and quantified the relative contributions of different components of the fragmentation process (decreases in fragment size, edge effects, increased isolation, and habitat degradation) to the overall effect. The effects of fragmentation on mutualisms were primarily driven by habitat degradation, edge effects, and fragment isolation, and, as predicted, they were consistently more negative on mutualisms than on antagonisms. For the most studied interaction type, seed dispersal, only certain components of fragmentation had significant (edge effects) or marginally significant (fragment size) effects. Seed size modulated the effect of fragmentation: species with large seeds showed stronger negative impacts of fragmentation via reduced dispersal rates. Our results reveal that different components of the habitat fragmentation process have varying impacts on key mutualisms. We also conclude that antagonistic interactions have been understudied in fragmented landscapes, most of the research has concentrated on particular types of mutualistic interactions such as seed dispersal, and that available studies of interspecific interactions have a strong geographical bias (arising mostly from studies carried out in Brazil, Chile, and the United States). Meta‐Análisis de los Efectos de la Fragmentación del Bosque sobre las Interacciones Interespecíficas     

Limitations of outsourcing on‐the‐ground biodiversity conservation

To counteract global species decline, modern biodiversity conservation engages in large projects, spends billions of dollars, and includes many organizations working simultaneously within regions. To add to this complexity, the conservation sector has hierarchical structure, where conservation actions are often outsourced by funders (foundations, government, etc.) to local organizations that work on‐the‐ground. In contrast, conservation science usually assumes that a single organization makes resource allocation decisions. This discrepancy calls for theory to understand how the expected biodiversity outcomes change when interactions between organizations are accounted for. Here, we used a game theoretic model to explore how biodiversity outcomes are affected by vertical and horizontal interactions between 3 conservation organizations: a funder that outsourced its actions and 2 local conservation organizations that work on‐the‐ground. Interactions between the organizations changed the spending decisions made by individual organizations, and thereby the magnitude and direction of the conservation benefits. We showed that funders would struggle to incentivize recipient organizations with set priorities to perform desired actions, even when they control substantial amounts of the funding and employ common contracting approaches to enhance outcomes. Instead, biodiversity outcomes depended on priority alignment across the organizations. Conservation outcomes for the funder were improved by strategic interactions when organizational priorities were well aligned, but decreased when priorities were misaligned. Meanwhile, local organizations had improved outcomes regardless of alignment due to additional funding in the system. Given that conservation often involves the aggregate actions of multiple organizations with different objectives, strategic interactions between organizations need to be considered if we are to predict possible outcomes of conservation programs or costs of achieving conservation targets.     

Cassava, maize and tree root development as affected by various agroforestry and cropping systems in Bénin, West Africa

Soil fertility levels, climate, aboveground interaction for light in plant canopies, and belowground interactions of the root systems for nutrients and water have an important influence on the performance of cropping systems. This study aims at identifying the impact of agroforestry treatments and fertilizer application on the root development of cassava-based cropping systems. At three sites in southern Bénin, the root development of intercropped maize (Zea mays) and cassava (Manihot esculenta) vs. sole-cropped cassava was monitored in an NPK fertilizer treatment and a no-fertilizer and no-mulch treatment. The latter represented local farmers’ practice. In addition, root development of sole-cropped cassava in three agroforestry systems was recorded at the same sites consisting of: (i) annually planted Cajanus cajan, (ii) perennial alleys, and (iii) a tree block of a Gliricidia sepium, Flemingia macrophylla, Parkia biglobosa, Millettia thonningii mixture. Soil monolith sampling was used to extract roots and generate data on the morphological development of root systems and their interactions. In general, intercropping reduced cassava root length density (RLD). Fertilizer applications significantly increased (P≤0.05) the RLD of intercropped maize and intercropped cassava at all sites. Annual alleys of C. cajan developed smaller RLD and root weight densities (RWD) than the perennial tree mixture, leading to less interference with cassava. Block arrangement of the tree mixture had detrimental effects on the cassava growth in the adjacent rows, indicated by high RLD and RWD of the tree mixture. However, the overall effect on cassava yield was positive, when the crop yield is calculated on an entire field basis.     

Measuring the complexity of interaction webs using vertical links between functional groups

Ecological insights into the usually high complexity of interaction webs demand a simplification of their structure to concentrate on the most important interactions within a community. One way to achieve this goal is to use functional groups (FGs). Using simple and partial Mantel tests the vertical interactions between FGs from different trophic levels were studied both at a disturbed grassland site and at a similar but undisturbed site. The resulting interaction structures of both ecosystems were compared. (i) An approximately 50% higher vertical FG-connectance could be found in the undisturbed than in the disturbed grassland; (ii) a much higher percentage of significant correlations did exist between FGs in the undisturbed than in the disturbed system; and (iii) the disturbed grassland was characterized by more simply structured biotic interaction patterns. From these results it was concluded that (a) Mantel tests are a useful tool for detecting significant interaction patterns (web links) between FGs, and that (b) FG-connectance is a powerful measure of complexity and functional diversity of communities.