Economically optimal marine reserves without spatial heterogeneity in a simple two-patch model

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Natural Resource Modeling 28 (2015): 244-255, doi:10.1111/nrm.12066.Bioeconomic analyses of spatial fishery models have established that marine reserves can be economically optimal (i.e., maximize sustainable profit) when there is some type of spatial heterogeneity in the system. Analyses of spatially continuous models and models with more than two discrete patches have also demonstrated that marine reserves can be economically optimal even when the system is spatially homogeneous. In this note we analyze a spatially homogeneous two-patch model and show that marine reserves can be economically optimal in this case as well. The model we study includes the possibility that fishing can damage habitat. In this model, marine reserves are necessary to maximize sustainable profit when dispersal between the patches is sufficiently high and habitat is especially vulnerable to damage.Graduate Research Fellowship and a Postdoctoral Research Fellowship in Biology Grant Number: DBI-1401332; US National Science Foundation Grant Numbers: OCE-1031256, DEB-1257545, DEB-11450172016-06-2

Habitat damage, marine reserves, and the value of spatial management

Author Posting. © Ecological Society of America, 2013. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 23 (2013): 959–971, doi:10.1890/12-0447.1.The biological benefits of marine reserves have garnered favor in the conservation community, but “no-take” reserve implementation is complicated by the economic interests of fishery stakeholders. There are now a number of studies examining the conditions under which marine reserves can provide both economic and ecological benefits. A potentially important reality of fishing that these studies overlook is that fishing can damage the habitat of the target stock. Here, we construct an equilibrium bioeconomic model that incorporates this habitat damage and show that the designation of marine reserves, coupled with the implementation of a tax on fishing effort, becomes both biologically and economically favorable as habitat sensitivity increases. We also study the effects of varied degrees of spatial control on fisheries management. Together, our results provide further evidence for the potential monetary and biological value of spatial management, and the possibility of a mutually beneficial resolution to the fisherman–conservationist marine reserve designation dilemma.M. G. Neubert acknowledges the support of the National Science Foundation (DMS-0532378, OCE-1031256) and a Thomas B. Wheeler Award for Ocean Science and Society. H. V. Moeller acknowledges support from a National Science Foundation Graduate Research Fellowship. This research is based in part on work supported by Award No. USA 00002 made by King Abdullah University of Science and Technology (KAUST)

The formation of marine kin structure : effects of dispersal, larval cohesion, and variable reproductive success

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Ecology 99 (2018): 2374-2384, doi:10.1002/ecy.2480.The spatial distribution of relatives has profound e ects on kin interactions, inbreeding, and inclusive tness. Yet, in the marine environment, the processes that generate patterns of kin structure remain understudied because larval dispersal on ocean currents was historically assumed to disrupt kin associations. Recent genetic evidence of co-occurring siblings challenges this assumption and raises the intriguing question of how siblings are found together after a (potentially) disruptive larval phase. Here, we develop individual based models to explore how stochastic processes operating at the individual level a ect expected kinship at equilibrium. Speci cally, we predict how limited dispersal, sibling cohesion, and variability in reproductive success di erentially a ect patterns of kin structure. All three mechanisms increase mean kinship within populations, but their spatial e ects are markedly di erent. We nd that: (1) when dispersal is limited, kinship declines monotonically as a function of the distance between individuals; (2) when siblings disperse cohesively, kinship increases within a site relative to between sites; and (3) when reproductive success varies, kinship increases equally at all distances. The di erential e ects of these processes therefore only become apparent when individuals are sampled at multiple spatial scales. Notably, our models suggest that aggregative larval behaviors, such as sibling cohesion, are not necessary to explain documented levels of relatedness within marine populations. Together, these ndings establish a theoretical framework for disentangling the drivers of marine kin structure.CCD was supported by a Weston Howland Jr. Postdoctoral Scholarship from WHOI. MGN was supported by a grant from the US NSF (DEB-1558904)

Marine reserves and optimal dynamic harvesting when fishing damages habitat

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kelly, M. R., Jr., Neubert, M. G., & Lenhart, S. Marine reserves and optimal dynamic harvesting when fishing damages habitat. Theoretical Ecology, 12(2), (2019): 131-144, doi:10.1007/s12080-018-0399-7.Marine fisheries are a significant source of protein for many human populations. In some locations, however, destructive fishing practices have negatively impacted the quality of fish habitat and reduced the habitat’s ability to sustain fish stocks. Improving the management of stocks that can be potentially damaged by harvesting requires improved understanding of the spatiotemporal dynamics of the stocks, their habitats, and the behavior of the harvesters. We develop a mathematical model for both a fish stock as well as its habitat quality. Both are modeled using nonlinear, parabolic partial differential equations, and density dependence in the growth rate of the fish stock depends upon habitat quality. The objective is to find the dynamic distribution of harvest effort that maximizes the discounted net present value of the coupled fishery-habitat system. The value derives both from extraction (and sale) of the stock and the provisioning of ecosystem services by the habitat. Optimal harvesting strategies are found numerically. The results suggest that no-take marine reserves can be an important part of the optimal strategy and that their spatiotemporal configuration depends both on the vulnerability of habitat to fishing damage and on the timescale of habitat recovery when fishing ceases.This manuscript is based upon the work supported by the National Science Foundation under Grant No. DEB-1558904 (to MGN) and also supported by the National Institute for Mathematical and Biological Synthesis, an Institute supported by the National Science Foundation through NSF Award #DBI-1300426, with additional support from The University of Tennessee, Knoxville

Fire increases invasive spread of Molinia caerulea mainly through changes in demographic parameters

Author Posting. © Ecological Society of America, 2005. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 15 (2005): 2097–2108, doi:10.1890/04-1762.We investigated the effects of fire on population growth rate and invasive spread of the perennial tussock grass Molinia caerulea. During the last decades, this species has invaded heathland communities in Western Europe, replacing typical heathland species such as Calluna vulgaris and Erica tetralix. M. caerulea is considered a major threat to heathland conservation. In 1996, a large and unintended fire destroyed almost one-third of the Kalmthoutse Heide, a large heathland area in northern Belgium. To study the impact of this fire on the population dynamics and invasive spread of M. caerulea, permanent monitoring plots were established both in burned and unburned heathland. The fate of each M. caerulea individual in these plots was monitored over four years (1997–2000). Patterns of seed dispersal were inferred from a seed germination experiment using soil cores sampled one month after seed rain at different distances from seed-producing plants. Based on these measures, we calculated projected rates of spread for M. caerulea in burned and unburned heathland. Elasticity and sensitivity analyses were used to determine vital rates that contributed most to population growth rate, and invasion speed. Invasion speed was, on average, three times larger in burned compared to unburned plots. Dispersal distances on the other hand, were not significantly different between burned and unburned plots indicating that differences in invasive spread were mainly due to differences in demography. Elasticities for fecundity and growth of seedlings and juveniles were higher for burned than for unburned plots, whereas elasticities for survival were higher in unburned plots. Finally, a life table response experiment (LTRE) analysis revealed that the effect of fire was mainly contributed by increases in sexual reproduction (seed production and germination) and growth of seedlings and juveniles. Our results clearly showed increased invasive spread of M. caerulea after fire, and call for active management guidelines to prevent further encroachment of the species and to reduce the probability of large, accidental fires in the future. Mowing of resprouted plants before flowering is the obvious management tactic to halt massive invasive spread of the species after fire.This work was supported by the Flemish Fund for Scientific Research (FWO) to HJ, the U.S. National Science foundation (DEB-0235692, OCE-0083976), and the U.S. Environmental Protection Agency (R-8290891) to MGN

Detecting reactivity

Author Posting. © Ecological Society of America, 2009. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 90 (2009): 2683-2688, doi:10.1890/08-2014.1.By definition, ecological systems at a stable equilibrium eventually return to the equilibrium point following a small perturbation. In the short term, however, perturbations can grow. Equilibria that exhibit transient growth following perturbation are said to be reactive. In this report, we present a statistical method for detecting reactivity from multivariate time series. The test is simple and computationally tractable, and it can be applied to short time series. Its main limitation is that it is based on a model of population dynamics that is linear on a logarithmic scale. Our results suggest that the test is robust when the dynamics are nonlinear on the log scale but that it may incorrectly classify an equilibrium as reactive when the reactivity is close to zero.This research was supported by a grant (DEB-0515639) from the U.S. National Science Foundation

Bioeconomics and biodiversity in harvested metacommunities : a patch-occupancy approach

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ecosphere 6, no. 11 (2015): 1-18, doi:10.1890/ES14-00503.1.We develop a coupled economic-metacommunity model to investigate the trade-off between diversity and profit for multispecies systems. The model keeps track of the presence or absence of species in habitat patches. With this approach, it becomes (relatively) simple to include more species than can typically be included in models that track species population density. We use this patch-occupancy framework to understand how profit and biodiversity are impacted by (1) community assembly, (2) pricing structures that value species equally or unequally, and (3) the implementation of marine reserves. We find that when local communities assemble slowly as a result of facilitative colonization, there are lower profits and optimal harvest rates, but the trade-off with diversity may be either large or small. The trade-off is diminished if later colonizing species are more highly valued than early colonizers. When the cost of harvesting is low, maximizing profits tends to sharply reduce biodiversity and maximizing diversity entails a large harvesting opportunity cost. In the models we analyze, marine reserves are never economically optimal for a profit-maximizing owner. However, management using marine reserves may provide low-cost biodiversity protection if the community is over-harvested.This research was supported by The Seaver Institute and the National Science Foundation (OCE-1031256) through grants awarded to J. B. Kellner and M. G. Neubert. E. A. Moberg was funded by NSF GRFP number 1122374 and MIT's Ida Green Fellowship

Intraguild predation enables coexistence of competing phytoplankton in a well-mixed water column

Author Posting. © Ecological Society of America, 2019. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology, (2019): e02874, doi: 10.1002/ecy.2874.Resource competition theory predicts that when two species compete for a single, finite resource, the better competitor should exclude the other. However, in some cases, weaker competitors can persist through intraguild predation, that is, by eating their stronger competitor. Mixotrophs, species that meet their carbon demand by combining photosynthesis and phagotrophic heterotrophy, may function as intraguild predators when they consume the phototrophs with which they compete for light. Thus, theory predicts that mixotrophy may allow for coexistence of two species on a single limiting resource. We tested this prediction by developing a new mathematical model for a unicellular mixotroph and phytoplankter that compete for light, and comparing the model's predictions with a laboratory experimental system. We find that, like other intraguild predators, mixotrophs can persist when an ecosystem is sufficiently productive (i.e., the supply of the limiting resource, light, is relatively high), or when species interactions are strong (i.e., attack rates and conversion efficiencies are high). Both our mathematical and laboratory models show that, depending upon the environment and species traits, a variety of equilibrium outcomes, ranging from competitive exclusion to coexistence, are possible.HVM and MGN designed the model. HVM and MDJ designed the experimental test system. HVM performed the model analysis, conducted the experiments, and analyzed the data. All authors wrote the paper. We thank Susanne Wilken for generously providing axenic CCMP 2951 and 1393 cultures for our use. R. Germain, S. Louca, G. Owens, N. Sharp, P. Thompson, and J. Yoder provided valuable feedback on figure design. We also thank J. Bronstein, S. Diehl, J. Huisman, C. Klausmeier, and four anonymous reviewers for comments on earlier versions of this manuscript. HVM was supported by a United States National Science Foundation Postdoctoral Research Fellowship in Biology (Grant DBI‐1401332) and a University of British Columbia Biodiversity Research Centre Postdoctoral Fellowship. This material is based upon work supported by the National Science Foundation under Grants OCE‐1655686 and OCE‐1436169, by a grant from the Simons Foundation/SFARI (561126, HMS), and by the Woods Hole Oceanographic Institution's Investment in Science Program. Research was also sponsored by the U.S. Army Research Office and was accomplished under Cooperative Agreement Number W911NF‐19‐2‐0026 for the Institute for Collaborative Biotechnologies

Acquired phototrophy stabilizes coexistence and shapes intrinsic dynamics of an intraguild predator and its prey

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Ecology Letters 19 (2016): 393-402, doi:10.1111/ele.12572.In marine ecosystems, acquired phototrophs|organisms that obtain their photo- synthetic ability by hosting endosymbionts or stealing plastids from their prey|are omnipresent. Such taxa function as intraguild predators yet depend on their prey to periodically obtain chloroplasts. We present new theory for the effects of acquired phototrophy on community dynamics by analyzing a mathematical model of this predator-prey interaction and experimentally verifying its predictions with a lab- oratory model system. We show that acquired phototrophy stabilizes coexistence, but that the nature of this coexistence exhibits a `paradox of enrichment:' as light increases, the coexistence between the acquired phototroph and its prey transitions from a stable equilibrium to boom-bust cycles whose amplitude increases with light availability. In contrast, heterotrophs and mixotrophic acquired phototrophs (that obtain <30% of their carbon from photosynthesis) do not exhibit such cycles. This prediction matches eld observations, in which only strict (>95% of carbon from photosynthesis) acquired phototrophs form blooms.HVM is supported by a United States National Science Foundation Postdoctoral Research Fellowship in Biology (Grant No. DBI-1401332). EP is supported by the Academy of Finland through research grant 276268. MDJ acknowledges NSF Grant No. IOS-1354773. MGN acknowledges support provided by the Independent Research and Development Program at the Woods Hole Oceanographic Institution.2017-02-0

A model for energetics and bioaccumulation in marine mammals with applications to the right whale

Author Posting. © Ecological Society of America, 2007. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 17 (2007): 2233–2250, doi:10.1890/06-0426.1.We present a dynamic energy budget (DEB) model for marine mammals, coupled with a pharmacokinetic model of a lipophilic persistent toxicant. Inputs to the model are energy availability and lipid-normalized toxicant concentration in the environment. The model predicts individual growth, reproduction, bioaccumulation, and transfer of energy and toxicant from mothers to their young. We estimated all model parameters for the right whale; with these parameters, reduction in energy availability increases the age at first parturition, increases intervals between reproductive events, reduces the organisms' ability to buffer seasonal fluctuations, and increases its susceptibility to temporal shifts in the seasonal peak of energy availability. Reduction in energy intake increases bioaccumulation and the amount of toxicant transferred from mother to each offspring. With high energy availability, the toxicant load of offspring decreases with birth order. Contrary to expectations, this ordering may be reversed with lower energy availability. Although demonstrated with parameters for the right whale, these relationships between energy intake and energetics and pharmacokinetics of organisms are likely to be much more general. Results specific to right whales include energy assimilation estimates for the North Atlantic and southern right whale, influences of history of energy availability on reproduction, and a relationship between ages at first parturition and calving intervals. Our model provides a platform for further analyses of both individual and population responses of marine mammals to pollution, and to changes in energy availability, including those likely to arise through climate change.This research was supported by the David and Lucile Packard Foundation, the U.S. National Science Foundation (DEB-9973518 and OCE-0083976), the U.S. Environmental Protection Agency (R-82908901-0), NOAA grant NA03NMF4720491, and the WHOI/MIT Joint Program in Oceanography