
Juan Carlos Villasenor Derbez
Postdoctoral Scholar, Hopkins Marine Station
All Publications
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Two Decades of Community-Based Marine Conservation Provide the Foundations for Future Action
FRONTIERS IN MARINE SCIENCE
2022; 9
View details for DOI 10.3389/fmars.2022.893104
View details for Web of Science ID 000829411500001
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Evaluating Conditions for Moored Fish Aggregating Device Fisheries Development in the Caribbean and Bermuda
FRONTIERS IN MARINE SCIENCE
2022; 9
View details for DOI 10.3389/fmars.2022.827068
View details for Web of Science ID 000805107700001
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Self-financed marine protected areas
ENVIRONMENTAL RESEARCH LETTERS
2021; 16 (12)
View details for DOI 10.1088/1748-9326/ac3439
View details for Web of Science ID 000719569700001
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Mapping global inputs and impacts from of human sewage in coastal ecosystems
PLOS ONE
2021; 16 (11): e0258898
Abstract
Coastal marine ecosystems face a host of pressures from both offshore and land-based human activity. Research on terrestrial threats to coastal ecosystems has primarily focused on agricultural runoff, specifically showcasing how fertilizers and livestock waste create coastal eutrophication, harmful algae blooms, or hypoxic or anoxic zones. These impacts not only harm coastal species and ecosystems but also impact human health and economic activities. Few studies have assessed impacts of human wastewater on coastal ecosystems and community health. As such, we lack a comprehensive, fine-resolution, global assessment of human sewage inputs that captures both pathogens and nutrient flows to coastal waters and the potential impacts on coastal ecosystems. To address this gap, we use a new high-resolution geospatial model to measure and map nitrogen (N) and pathogen-fecal indicator organisms (FIO)-inputs from human sewage for ~135,000 watersheds globally. Because solutions depend on the source, we separate nitrogen and pathogen inputs from sewer, septic, and direct inputs. Our model indicates that wastewater adds 6.2Tg nitrogen into coastal waters, which is approximately 40% of total nitrogen from agriculture. Of total wastewater N, 63% (3.9Tg N) comes from sewered systems, 5% (0.3Tg N) from septic, and 32% (2.0Tg N) from direct input. We find that just 25 watersheds contribute nearly half of all wastewater N, but wastewater impacts most coastlines globally, with sewered, septic, and untreated wastewater inputs varying greatly across watersheds and by country. Importantly, model results find that 58% of coral and 88% of seagrass beds are exposed to wastewater N input. Across watersheds, N and FIO inputs are generally correlated. However, our model identifies important fine-grained spatial heterogeneity that highlight potential tradeoffs and synergies essential for management actions. Reducing impacts of nitrogen and pathogens on coastal ecosystems requires a greater focus on where wastewater inputs vary across the planet. Researchers and practitioners can also overlay these global, high resolution, wastewater input maps with maps describing the distribution of habitats and species, including humans, to determine the where the impacts of wastewater pressures are highest. This will help prioritize conservation efforts.Without such information, coastal ecosystems and the human communities that depend on them will remain imperiled.
View details for DOI 10.1371/journal.pone.0258898
View details for Web of Science ID 000755112500013
View details for PubMedID 34758036
View details for PubMedCentralID PMC8580218
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Asymmetry across international borders: Research, fishery and management trends and economic value of the giant sea bass (Stereolepis gigas)
FISH AND FISHERIES
2021; 22 (6): 1392-1411
View details for DOI 10.1111/faf.12594
View details for Web of Science ID 000680927600001
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Reply to "Catch rate composition affects assessment of protected area impacts"
NATURE COMMUNICATIONS
2021; 12 (1): 1590
View details for DOI 10.1038/s41467-021-21608-3
View details for Web of Science ID 000629597700015
View details for PubMedID 33707422
View details for PubMedCentralID PMC7952418
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WTO must ban harmful fisheries subsidies.
Science (New York, N.Y.)
2021; 374 (6567): 544
Abstract
[Figure: see text].
View details for DOI 10.1126/science.abm1680
View details for PubMedID 34709891
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Status and trends of moored fish aggregating device (MFAD) fisheries in the Caribbean and Bermuda
MARINE POLICY
2020; 121
View details for DOI 10.1016/j.marpol.2020.104148
View details for Web of Science ID 000595873000007
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Impact of two of the world's largest protected areas on longline fishery catch rates
NATURE COMMUNICATIONS
2020; 11 (1): 979
Abstract
Two of the largest protected areas on earth are U.S. National Monuments in the Pacific Ocean. Numerous claims have been made about the impacts of these protected areas on the fishing industry, but there has been no ex post empirical evaluation of their effects. We use administrative data documenting individual fishing events to evaluate the economic impact of the expansion of these two monuments on the Hawaii longline fishing fleet. Surprisingly, catch and catch-per-unit-effort are higher since the expansions began. To disentangle the causal effect of the expansions from confounding factors, we use unaffected control fisheries to perform a difference-in-differences analysis. We find that the monument expansions had little, if any, negative impacts on the fishing industry, corroborating ecological models that have predicted minimal impacts from closing large parts of the Pacific Ocean to fishing.
View details for DOI 10.1038/s41467-020-14588-3
View details for Web of Science ID 000517260700012
View details for PubMedID 32080189
View details for PubMedCentralID PMC7033108
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Environmental market design for large-scale marine conservation
NATURE SUSTAINABILITY
2020; 3 (3): 234-+
View details for DOI 10.1038/s41893-019-0459-z
View details for Web of Science ID 000507792200002
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Mapping status and conservation of global at-risk marine biodiversity
CONSERVATION LETTERS
2019; 12 (4)
View details for DOI 10.1111/conl.12651
View details for Web of Science ID 000482077700009
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Spatial variation in allometric growth of invasive lionfish has management implications
PEERJ
2019; 7: e6667
Abstract
Lionfish (Pterois volitans/miles) are an invasive species in the Western Atlantic and the Caribbean. Improving management of invasive lionfish populations requires accurate total biomass estimates, which depend on accurate estimates of allometric growth; sedentary species like lionfish often exhibit high levels of spatial variation in life history characteristics. We reviewed 17 published length-weight relationships for lionfish taken throughout their invasive range and found regional differences that led to significant misestimates when calculating weight from length observations. The spatial pattern we observed is consistent with findings from other studies focused on genetics or length-at-age. Here, the use of ex situ parameter values resulted in total biomass estimates between 76.2% and 140% of true observed biomass, and up to a threefold under- or overestimation of total weight for an individual organism. These findings can have implications for management in terms of predicting effects on local ecosystems, evaluating the effectiveness of removal programs, or estimating biomass available for harvest.
View details for DOI 10.7717/peerj.6667
View details for Web of Science ID 000462981800009
View details for PubMedID 30972253
View details for PubMedCentralID PMC6450370
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An interdisciplinary evaluation of community-based TURF-reserves.
PloS one
2019; 14 (8): e0221660
Abstract
Coastal marine ecosystems provide livelihoods for small-scale fishers and coastal communities around the world. Small-scale fisheries face great challenges since they are difficult to monitor, enforce, and manage, which may lead to overexploitation. Combining territorial use rights for fisheries (TURF) with no-take marine reserves to create TURF-reserves can improve the performance of small-scale fisheries by buffering fisheries from environmental variability and management errors, while ensuring that fishers reap the benefits of conservation investments. Since 2012, 18 old and new community-based Mexican TURF-reserves gained legal recognition thanks to a regulation passed in 2012; their effectiveness has not been formally evaluated. We combine causal inference techniques and the Social-Ecological Systems framework to provide a holistic evaluation of community-based TURF-reserves in three coastal communities in Mexico. We find that, overall, reserves have not yet achieved their stated goals of increasing the density of lobster and other benthic invertebrates, nor increasing lobster catches. A lack of clear ecological and socioeconomic effects likely results from a combination of factors. First, some of these reserves might be too young for the effects to show (reserves were 6-10 years old). Second, the reserves are not large enough to protect mobile species, like lobster. Third, variable and extreme oceanographic conditions have impacted harvested populations. Fourth, local fisheries are already well managed, and while reserves may protect populations within its boundaries, it is unlikely that reserves might have a detectable effect in catches. However, even small reserves are expected to provide benefits for sedentary invertebrates over longer time frames, with continued protection. These reserves may provide a foundation for establishing additional, larger marine reserves needed to effectively conserve mobile species.
View details for DOI 10.1371/journal.pone.0221660
View details for PubMedID 31442289
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Feeding ecology of invasive lionfish (Pterois volitans and Pterois miles) in the temperate and tropical western Atlantic
BIOLOGICAL INVASIONS
2018; 20 (9): 2567-2597
View details for DOI 10.1007/s10530-018-1720-5
View details for Web of Science ID 000441112500020
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A user-friendly tool to evaluate the effectiveness of no-take marine reserves
PLOS ONE
2018; 13 (1): e0191821
Abstract
Marine reserves are implemented to achieve a variety of objectives, but are seldom rigorously evaluated to determine whether those objectives are met. In the rare cases when evaluations do take place, they typically focus on ecological indicators and ignore other relevant objectives such as socioeconomics and governance. And regardless of the objectives, the diversity of locations, monitoring protocols, and analysis approaches hinder the ability to compare results across case studies. Moreover, analysis and evaluation of reserves is generally conducted by outside researchers, not the reserve managers or users, plausibly thereby hindering effective local management and rapid response to change. We present a framework and tool, called "MAREA", to overcome these challenges. Its purpose is to evaluate the extent to which any given reserve has achieved its stated objectives. MAREA provides specific guidance on data collection and formatting, and then conducts rigorous causal inference analysis based on data input by the user, providing real-time outputs about the effectiveness of the reserve. MAREA's ease of use, standardization of state-of-the-art inference methods, and ability to analyze marine reserve effectiveness across ecological, socioeconomic, and governance objectives could dramatically further our understanding and support of effective marine reserve management.
View details for PubMedID 29381762