Implications of Complex Connectivity Patterns, Disturbance, Allee Effects, and Fisheries in the Dynamics of Marine Metapopulations - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Implications of Complex Connectivity Patterns, Disturbance, Allee Effects, and Fisheries in the Dynamics of Marine Metapopulations write by Tania Sarith Peña-Baca. This book was released on 2014. Implications of Complex Connectivity Patterns, Disturbance, Allee Effects, and Fisheries in the Dynamics of Marine Metapopulations available in PDF, EPUB and Kindle. Nearshore populations have been depleted and some have not yet recovered. Therefore, theoretical studies focus on improving fisheries management and designing marine protected areas (MPAs). Depleted populations may be undergoing an Allee effect, i.e. a decrease in fitness at low densities. Here, I constructed a marine metapopulation model that included pre- and post-dispersal Allee effects using a network theory approach. Networks represent metapopulations as groups of nodes connected by dispersal paths. With this model I answered four questions: What is the role of Allee effects on habitat occupancy? Are MPAs effective in recovering exploited populations? What is the importance of larval dispersal patterns in preventing local extinctions due to exploitation and Allee effects? Can exploitation fragment nearshore metapopulations? When weak Allee effects are included, habitat occupancy drops as larval retention decreases because more larvae are lost to unsuitable habitat. With strong Allee effects habitat occupancy also drops at high larval retention because more larvae are needed to overcome the Allee effect. Post-dispersal Allee effects seem more detrimental for nearshore metapopulations. MPA effectiveness seems also lower in a post-dispersal Allee effect scenario. In overexploited systems, local populations that go extinct are also less likely to recover even after protecting the whole coastline. In exploited nearshore metapopulations with Allee effects, local occupancy or the recovery of local populations depends not only on larval inflow from neighbor populations, but also on larval inflow for these neighbors. Nearshore metapopulations with intense fishing mortality and Allee effects may also suffer a decrease in dispersal strength and fragmentation. Population fragmentation occurs when large populations are split into smaller groups. A tool for detecting partitioning in a network is modularity. The modularity analysis performed for red abalone in the Southern California Bight showed that exploitation increases partitioning through time before the entire metapopulation collapses. These findings call for research effort in estimating the strength of potential Allee effects to prevent stock collapse and assess MPA effectiveness, evaluating the predictability of local occupancy by centrality metrics to help identify important sites for conservation, and using modularity analysis to quantify the health of exploited metapopulations to prevent their collapse.
Managing for the Future: Understanding the Relative Roles of Climate and Fishing on Structure and Dynamics of Marine Ecosystems
Managing for the Future: Understanding the Relative Roles of Climate and Fishing on Structure and Dynamics of Marine Ecosystems - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Managing for the Future: Understanding the Relative Roles of Climate and Fishing on Structure and Dynamics of Marine Ecosystems write by Alida Bundy. This book was released on 2021-11-29. Managing for the Future: Understanding the Relative Roles of Climate and Fishing on Structure and Dynamics of Marine Ecosystems available in PDF, EPUB and Kindle.
Dispersal, Fishing, and the Conservation of Marine Species
Dispersal, Fishing, and the Conservation of Marine Species - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Dispersal, Fishing, and the Conservation of Marine Species write by Malin La Farge Pinsky. This book was released on 2011. Dispersal, Fishing, and the Conservation of Marine Species available in PDF, EPUB and Kindle. A central goal of ecology is to understand the forces driving the distribution and abundance of organisms. However, understanding the population dynamics of high-dispersal species, their conservation, and the connections between population dynamics and evolution remains difficult. It is in this context that marine organisms provide a particularly intriguing and challenging study system. Their population dynamics are often highly stochastic, most species have a great ability to disperse, and as the last group of wild species exploited commercially, their ecology and evolution can be strongly influenced by human behavior. By using population genetics, modeling, and meta-analysis, this thesis investigates the spatial ecology of reef fish and the causes and evolutionary consequences of global fisheries collapse. One of the first challenges in understanding spatial population dynamics is obtaining accurate measurements of dispersal abilities. This has been especially difficult for marine species with pelagic larvae. In Chapter 1, I apply a new approach to measuring single-generation dispersal kernels in Clark's anemonefish (Amphiprion clarkii) in the central Philippines. After developing two methods for measuring the strength of local genetic drift, my results suggest that larval dispersal kernels in A. clarkii had a spread near 11 km (4-27 km). This study shows that ecologically relevant larval dispersal can be estimated with widely available genetic methods when effective density is measured carefully through cohort sampling and ecological censuses. In Chapter 2, I use dispersal kernels to develop a model for population openness. Openness refers to the degree to which populations are replenished by immigrants or by local production, a factor that has strong implications for population dynamics, species interactions, and response to exploitation. It is also a population trait that has been increasingly measured empirically, though we have until now lacked theory for predicting population openness. I show that considering habitat isolation elegantly explains the existence of surprisingly closed populations in high dispersal species, and that relatively closed populations are expected when patch spacing is more than twice the standard deviation of a species' dispersal kernel. In addition, empirical scales of habitat patchiness on coral reefs are sufficient to create both largely open and largely closed populations. We predict that habitat patchiness has strong control over population replenishment pathways for a wide range of marine and terrestrial species with a highly dispersive life stage. While the first tow chapters have strong implications for the design of regional marine protected areas, I turn to global conservation questions in Chapters 3 and 4. I first ask which marine fishes are most vulnerable to human impacts. Surveys of terrestrial species have suggested that large-bodied species and top predators are the most at risk, but there has been no global test of this hypothesis in the sea. Contrary to expectations, two datasets compiled from around the world suggest that up to twice as many fisheries for small, low trophic level species have collapsed as compared to those for large predators. I then show that collapsed and overfished species have lower genetic diversity than their close relatives. While the ecological and ecosystem impacts of harvesting wild populations have long been recognized, it has been controversial how widespread evolutionary impacts are. Using a meta-analytical approach across 37 taxonomically paired comparisons, I find on average 19% fewer alleles per locus in overfished species, but little difference in heterozygosity. I confirm with simulations that these results are consistent with a recent population bottleneck. These results suggest that the genetic impacts of overharvest are widespread, even among abundant species. A loss of allelic richness has implications for the long-term evolutionary potential of species.
Effects of Isolation on Metapopulation Dynamics in Small-world Networks
Effects of Isolation on Metapopulation Dynamics in Small-world Networks - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Effects of Isolation on Metapopulation Dynamics in Small-world Networks write by Alaina Bernard. This book was released on 2007. Effects of Isolation on Metapopulation Dynamics in Small-world Networks available in PDF, EPUB and Kindle. Simulation models are valuable for making predictions that may be tested in natural systems and for understanding observed patterns. The simulation model developed for this thesis evaluates the effects of spatial network architecture, including organism dispersal patterns and isolation of habitats, on metapopulations. Two fields were merged throughout this project: metapopulation biology and small-world network theory. Small-world networks are characterized in their extremes as scale-free or single-scale. These models potentially simulate the networks of habitats and corridors in which metapopulations operate. Small-world network theory has been used to describe systems as diverse as rivers, the world-wide-web, and protein interactions, but has not been used as an experimental treatment for metapopulation dynamics. I tested the effects of growth rate, dispersal pattern, network architecture (scale-free and single-scale), attack type (targeted or random), and attack severity (0, 5, 10, 20, or 40% attacked populations) on metapopulation size and inter-population variation in a simulated system designed to be relevant to conservation biology and ecology. Metapopulation size and inter-population variation changed due to combinations of dispersal pattern, growth rate, and attack severity. Specifically, metapopulations were most affected by a combination of unidirectional dispersal and low growth rate in both metapopulation number and inter-population variation. However, a significant difference between scale-free and single-scale metapopulations was not found due to a low connectivity in the modeled networks as well as limitations of experimental assumptions. However, future studies that alter the model's assumptions could improve understanding of the influence of landscape structure on at-risk metapopulations.
Dynamic Geography of Marine Fish Populations
Dynamic Geography of Marine Fish Populations - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Dynamic Geography of Marine Fish Populations write by Alec D. MacCall. This book was released on 1990. Dynamic Geography of Marine Fish Populations available in PDF, EPUB and Kindle.
