Loren McClenachan

Conservation implications of historic sea turtle nesting beach loss

Populations of endangered Caribbean sea turtles are far more depleted than realized because current conservation assessments do not reflect historic nesting data. We used historical sources to analyze changes in the numbers of nesting populations and population sizes for green and hawksbill turtles on all known nesting beaches in the Caribbean over the past millennium. We present the first maps of historic nesting populations, which provide the basis for an objective measure of changes in distribution and abundance. Our results indicate that 20% of historic nesting sites have been lost entirely and 50% of the remaining nesting sites have been reduced to dangerously low populations. Recent conservation efforts have resulted in large population increases at several nesting sites, but loss of widespread nesting throughout the Caribbean and reductions in the Caribbean-wide population since human hunting began indicate that Caribbean turtles are far from recovered. Focusing attention on a small number of nesting populations is a risk-prone strategy; conservation programs should instead broaden their scope to protect both large and small nesting populations throughout the Caribbean.

Large-scale absence of sharks on reefs in the greater-Caribbean: a footprint of human pressures.

Background In recent decades, large pelagic and coastal shark populations have declined dramatically with increased fishing; however, the status of sharks in other systems such as coral reefs remains largely unassessed despite a long history of exploitation. Here we explore the contemporary distribution and sighting frequency of sharks on reefs in the greater-Caribbean and assess the possible role of human pressures on observed patterns. Methodology/Principal Findings We analyzed 76,340 underwater surveys carried out by trained volunteer divers between 1993 and 2008. Surveys were grouped within one km2 cells, which allowed us to determine the contemporary geographical distribution and sighting frequency of sharks. Sighting frequency was calculated as the ratio of surveys with sharks to the total number of surveys in each cell. We compared sighting frequency to the number of people in the cell vicinity and used population viability analyses to assess the effects of exploitation on population trends. Sharks, with the exception of nurse sharks occurred mainly in areas with very low human population or strong fishing regulations and marine conservation. Population viability analysis suggests that exploitation alone could explain the large-scale absence; however, this pattern is likely to be exacerbated by additional anthropogenic stressors, such as pollution and habitat degradation, that also correlate with human population. Conclusions/Significance Human pressures in coastal zones have lead to the broad-scale absence of sharks on reefs in the greater-Caribbean. Preventing further loss of sharks requires urgent management measures to curb fishing mortality and to mitigate other anthropogenic stressors to protect sites where sharks still exist. The fact that sharks still occur in some densely populated areas where strong fishing regulations are in place indicates the possibility of success and encourages the implementation of conservation measures.

Extinction rate, historical population structure and ecological role of the Caribbean monk seal

The productivity and biomass of pristine coral reef ecosystems is poorly understood, particularly in the Caribbean where communities have been impacted by overfishing and multiple other stressors over centuries. Using historical data on the spatial distribution and abundance of the extinct Caribbean monk seal (Monachus tropicalis), this study reconstructs the population size, structure and ecological role of this once common predator within coral reef communities, and provides evidence that historical reefs supported biomasses of fishes and invertebrates up to six times greater than those found on typical modern Caribbean reefs. An estimated 233 000–338 000 monk seals were distributed among 13 colonies across the Caribbean. The biomass of reef fishes and invertebrates required to support historical seal populations was 732–1018 g m−2 of reefs, which exceeds that found on any Caribbean reef today and is comparable with those measured in remote Pacific reefs. Quantitative estimates of historically dense monk seal colonies and their consumption rates on pristine reefs provide concrete data on the magnitude of decline in animal biomass on Caribbean coral reefs. Realistic reconstruction of these past ecosystems is critical to understanding the profound and long-lasting effect of human hunting on the functioning of coral reef ecosystems.

Historical reconstruction reveals recovery in Hawaiian coral reefs

Coral reef ecosystems are declining worldwide, yet regional differences in the trajectories, timing and extent of degradation highlight the need for in-depth regional case studies to understand the factors that contribute to either ecosystem sustainability or decline. We reconstructed social-ecological interactions in Hawaiian coral reef environments over 700 years using detailed datasets on ecological conditions, proximate anthropogenic stressor regimes and social change. Here we report previously undetected recovery periods in Hawaiian coral reefs, including a historical recovery in the MHI (∼AD 1400–1820) and an ongoing recovery in the NWHI (∼AD 1950–2009+). These recovery periods appear to be attributed to a complex set of changes in underlying social systems, which served to release reefs from direct anthropogenic stressor regimes. Recovery at the ecosystem level is associated with reductions in stressors over long time periods (decades+) and large spatial scales (>103 km2). Our results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to long-term trajectories of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts.

Committing to socially responsible seafood

Ocean science must evolve to meet social challenges in the seafood sector Seafood is the worlds most internationally traded food commodity. Approximately three out of every seven people globally rely on seafood as a primary source of animal protein (1). Revelations about slavery and labor rights abuses in fisheries have sparked outrage and shifted the conversation (2, 3), placing social issues at the forefront of a sector that has spent decades working to improve environmental sustainability. In response, businesses are seeking to reduce unethical practices and reputational risks in their supply chains. Governments are formulating policy responses, and nonprofit and philanthropic organizations are deploying resources and expertise to address critical social issues. Yet the scientific community has not kept pace with concerns for social issues in the sector. As the United Nations Ocean Conference convenes in New York (5 to 9 June), we propose a framework for social responsibility and identify key steps the scientific community must take to inform policy and practice for this global challenge.

Mounting Evidence for Historical Overfishing and Long-term Degradation of Caribbean Marine Ecosystems: Comment on Julio Baisre's "Setting a Baseline for Caribbean Fisheries"

The central claim of Baisre’s (2010) article is that no significant ecological change occurred in the Caribbean before the middle of the twentieth century. The assumption that historical fisheries’ impacts were low and populations of marine animals just naturally small is common, and arises primarily because long-term data are difficult to find and interpret, and often lack the uniformity demanded by modern fisheries science. However, when rigorous historical ecological analyses are undertaken, the weight of evidence has shown both assumptions to be false: historical fishing was more intensive

Ghost reefs: Nautical charts document large spatial scale of coral reef loss over 240 years

Nautical charts from the 18th century document loss of nearshore coral reef habitat, revealing a shifted spatial baseline. Massive declines in population abundances of marine animals have been documented over century-long time scales. However, analogous loss of spatial extent of habitat-forming organisms is less well known because georeferenced data are rare over long time scales, particularly in subtidal, tropical marine regions. We use high-resolution historical nautical charts to quantify changes to benthic structure over 240 years in the Florida Keys, finding an overall loss of 52% (SE, 6.4%) of the area of the seafloor occupied by corals. We find a strong spatial dimension to this decline; the spatial extent of coral in Florida Bay and nearshore declined by 87.5% (SE, 7.2%) and 68.8% (SE, 7.5%), respectively, whereas that of offshore areas of coral remained largely intact. These estimates add to finer-scale loss in live coral cover exceeding 90% in some locations in recent decades. The near-complete elimination of the spatial coverage of nearshore coral represents an underappreciated spatial component of the shifting baseline syndrome, with important lessons for other species and ecosystems. That is, modern surveys are typically designed to assess change only within the species’ known, extant range. For species ranging from corals to sea turtles, this approach may overlook spatial loss over longer time frames, resulting in both overly optimistic views of their current conservation status and underestimates of their restoration potential.

Toward principles of historical ecology

Rising temperatures and sea levels, biological homogenization and biodiversity loss, habitat fragmentation, and other environmental changes are dramatically reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes has become one of the central challenges facing environmental scientists and managers today. Yet to do so requires a long-term perspective on environmental systems that predates many of the accelerated anthropogenic impacts of the recent past. How, then, can we understand these changes in the context of decadeand century-scale ecosystem trajectories and human history? What was the structure, function, and dynamics of ecosystems like before these changes? And how have people shaped these systems over time? Th ese questions are the domain of historical ecology. Historical ecology is the study of nature over time, oft en (though not necessarily) with a focus on human–environment interactions and the causes and consequences of changes caused by human actions in the recent past ( Crumley, 2003 ; Rhemtulla and Mladenoff , 2007 ). Th e fi eld includes both researchers who wish to document ecological patterns and dynamics in the recent past using historical methods, as well as those interested in historicizing ecology— that is, understanding the relationships between nature and human culture over time (cf. Szabo [2014] for a detailed treatment). It draws on a broad range of qualitative and quantitative sources that vary in temporal and spatial coverage, require creative and thoughtful methods to synthesize and interpret, and are oft en integrated in ways that cross traditional disciplinary boundaries ( Fig. 1 ). Data include traditional archival sources such as written documents, maps, oral histories, land surveys, landscape views and photography, along with biological and physical data such as sediment and pollen records, tree rings, species lists, and habitat relationships ( Swetnam et al., 1999 ; Egan and Howell, 2001 ; Vellend et al., 2013 ). While relying on data from the past, historical ecology is an inherently future-oriented discipline given its emphasis on temporal dynamics and change trajectories ( Higgs et al., 2014 ). It provides vivid narratives of past landscapes and change that are of interest to specialists and nonspecialists alike (e.g., Sanderson, 2009 ; Grossinger, 2012 ). Historical ecology is part of a long tradition of understanding relationships between humans and environmental change and shares strong topical and methodological affinities with paleoecology, environmental history, and historical geography. It is similar to “temporal ecology” (sensu Wolkovich et al., 2014 ), though temporal ecology relies more on time series data, rather than integrating a broad array of data types within their historical context. Historical ecology has much in common with landscape and restoration ecology, ecological subfi elds that emphasize spatial patterns and processes, human–environment interactions, and temporal dynamism. As a fi eld, historical ecology largely operates at the intersection of ecology, history, anthropology, and geography, using tools and techniques from all four disciplines to help people conceive of what populations, communities, ecosystems, and landscapes existed in the past and how they have changed over time ( Szabó, 2014 ). It also relies heavily on the history of science, since interpretation of oft en fragmentary, qualitative, and idiosyncratic historical data requires an understanding of the historical, scientifi c, and cultural contexts in which past records and scientifi c data were produced ( Raby, 2015 ). Studies cast a broad net of topics of interest, from traditional ecological questions such as documenting population abundance and community composition, habitat distribution, and ecological processes and functions, to geographic questions such as changes in geophysical patterns and processes 1 Manuscript received 18 February 2017; revision accepted 7 April 2017. 2 Resilient Landscapes Program, San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804 USA; 3 Department of Geography, University of California Berkeley, 565 McCone Hall, Berkeley, California 94720 USA; 4 Environmental Studies, Colby College, 5351 Mayflower Hill, Waterville, Maine 04901 USA; 5 School of Environment, Resources and Sustainability, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G; 6 Wildlife Conservation Society Global Conservation Programs, 2300 Southern Blvd, Bronx, New York 10460 USA; 7 Forest and Conservation Sciences, University of British Columbia, 3609-2424 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4; 8 School of History, Philosophy, and Religion, Oregon State University, 322 Milam Hall, Corvallis, Oregon 97331 USA; and 9 School of Environmental Studies, University of Victoria, Room 205, House 4, Victoria, British Columbia, Canada V8P 5C2 10 Author for correspondence (e-mail: erin@sfei.org) doi:10.3732/ajb.1700070 O N T H E N AT U R E O F T H I N G S : E S S AY S New Ideas and Directions in Botany

Collateral damage to marine and terrestrial ecosystems from Yankee whaling in the 19th century

Abstract Yankee whalers of the 19th century had major impacts on populations of large whales, but these leviathans were not the only taxa targeted. Here, we describe the “collateral damage,” the opportunistic or targeted taking of nongreat whale species by the American whaling industry. Using data from 5,064 records from 79 whaling logs occurring between 1840 and 1901, we show that Yankee whalers captured 5,255 animals across three large ocean basins from 32 different taxonomic categories, including a wide range of marine and terrestrial species. The taxa with the greatest number of individuals captured were walruses (Odobenus rosmarus), ducks (family Anatidae), and cod (Gadus sp.). By biomass, the most captured species were walruses, grampus (a poorly defined group within Odontoceti), and seals (family Otariidae). The whalers captured over 2.4 million kg of nongreat whale meat equaling approximately 34 kg of meat per ship per day at sea. The species and areas targeted shifted over time in response to overexploitation of whale populations, with likely intensive local impacts on terrestrial species associated with multiyear whaling camps. Our results show that the ecosystem impacts of whaling reverberated on both marine and coastal environments.

Conservation implications of omitting historical data sources: response to Baisre

Historical ecology has made important contributions to conservation biology, broadening our understanding of long-term changes to species and ecosystems, of their structure and function before pervasive human impact, and of the possibilities for recovery and restoration (Rick & Lockwood 2012). Its research model relies on archaeological and historical records—which can be incomplete—and often makes use of sources that are imprecise by modern ecological standards. For these reasons, Baisre (2013) argues that previous historical ecology research on Caribbean monk seals (Monachus tropicalis) was flawed. He re-examined historical and archaeological records previously compiled by McClenachan and Cooper (2008) and others and concluded that rather than a ubiquitous predator in Caribbean reefs, monk seals were “naturally rare,” persisting only “as a small fragmented population” at the time of first European contact. However, Baisre’s conclusion results from a limited re-examination of historical documents and faulty assumptions and has implications for historical ecology and conservation biology more broadly. Here, we build on a previous discussion (McClenachan et al. 2010) to address Baisre’s problematic approach. We limited our comments to two issues with broad application to future historical ecology research. First, central to Baisre’s conclusion is his assessment of the historical record as insufficient, particularly with respect to a regional or international trade in seal oil, a commonly cited driver of population decline and ultimate extinction. Although sailors and natural historians in the early decades of the 18th century described a substantial hunt of Caribbean monk seals in certain locations—such as up to 100 seals killed per night in the Bahamas (Sloane 1707)—Baisre discounted these written accounts, claiming that a seal trade should have left a more complete historical record. As a result, he concluded that seal populations were too rare to support exploitation. However, this conclusion is based on a limited re-examination of historical documents and fails to consider the variety of sources that provide insight into past change. In particular, Baisre considered only published documents that could be found in libraries or online and did not distinguish between narrative accounts and official documents generated by colonial settlement and trade. As a result, he overlooked important unpublished government documents, which are kept in archives in their original form and not typically reproduced for publication. In contrast, McClenachan and Cooper (2008) visited more than 20 archives to collect historical source documents. These sources included British colonial shipping records that document trade in seal oil and skins (Fig. 1) in the same location and period where natural historians (Sloane 1707) and sailors (Bruce 1782) describe hunting seals for oil. Together, these sources counter Baisre’s conclusion of historical rarity of Caribbean monk seals and underscore the need for a thorough review of historical documents. Second, Baisre dismisses large quantities of anecdotal data, or narrative historical sources, stating that they do “not meet the basic requirements of ordinary zoological samples,” thus introducing a strong bias of what constitutes reliable observation. Although Pauly (1995) argues for the use of anecdotes to evaluate ecosystem change, the term anecdote connotes a lack of credibility in some contexts (Haggan et al. 2007). This is problematic because much historical ecology research requires narrative historical sources to document species’ occurrences. Indeed, most of what is known about Caribbean monk seals after European contact derives from descriptions left by sailors, settlers, and natural historians. Baisre dismisses an account by Hans Sloan, a respected 17th century scientist and the founder of the British Museum, and seven others describing a seal oil trade. Likewise, Baisre rejects observations of seals across the Caribbean basin, including the Lesser Antilles, South America, and Florida and concludes that seals were found only on “small islands and isolated banks.” Excluding historical sources on the basis of modern biases erodes the research process and can fundamentally alter conclusions. Failing to conduct a thorough review of historical sources and to incorporate anecdotal information can lead to misleading results and have important conservation implications. In this case, Baisre’s limited re-analysis of historical sources led to the conclusion that monk seals were naturally rare and therefore ecologists should not consider the possibility that Caribbean reef ecosystems were productive enough to support abundant mesopredators. This, in turn, lowers expectations for conservation and restoration of Caribbean reef ecosystems. As well, a judgment of natural rarity can be used to support the argument that the extinction of Caribbean monk seals was primarily the result of a natural process rather than anthropogenic. Ultimately, a judgment of natural rarity reduces the significance of the extinction event, because losing rare species is less troublesome than losing species that were historically abundant.