Prioritizing sites for conservation based on similarity to historical baselines and feasibility of protection.

The concept of shifting baselines in conservation science implies advocacy for the use of historical knowledge to inform these baselines but does not address the feasibility of restoring sites to those baselines. In many regions, conservation feasibility varies among sites due to differences in resource availability, statutory power, and land-owner participation. We used zooarchaeological records to identify a historical baseline of the freshwater mussel community's composition before Euro-American influence at a river-reach scale (i.e., a kilometer stretch of river that is abiotically similar) in the Leon River of central Texas (U.S.A.). We evaluated how the community reference position and the feasibility of conservation might enable identification of sites where conservation actions would preserve historically representative communities and be likely to succeed. We devised a conceptual model that incorporated community information and landscape factors to link the best conservation areas to potential cost and conservation benefits. Using fuzzy ordination, we identified modern mussel beds that were most like the historical baseline. We then quantified housing density and land use near each river reach identified to estimate feasibility of habitat restoration. Using our conceptual framework, we identified reaches of high conservation value (i.e., contain the best mussel beds) and where restoration actions would be most likely to succeed. Reaches above Lake Belton were most similar in species composition and relative abundance to zooarchaeological sites. A subset of these mussel beds occurred in locations where conservation actions appeared most feasible. Our results show how to use zooarchaeological data (biodiversity data often readily available) and estimates of conservation feasibility to inform conservation priorities at a local spatial scale.

Integrating archaeology and ancient DNA analysis to address invasive species colonization in the Gulf of Alaska.

The intentional and unintentional movement of plants and animals by humans has transformed ecosystems and landscapes globally. Assessing when and how a species was introduced are central to managing these transformed landscapes, particularly in island environments. In the Gulf of Alaska, there is considerable interest in the history of mammal introductions and rehabilitating Gulf of Alaska island environments by eradicating mammals classified as invasive species. The Arctic ground squirrel (Urocitellus parryii) is of concern because it affects vegetation and seabirds on Gulf of Alaska islands. This animal is assumed to have been introduced by historic settlers; however, ground squirrel remains in the prehistoric archaeological record of Chirikof Island, Alaska, challenge this timeline and suggest they colonized the islands long ago. We used 3 lines of evidence to address this problem: direct radiocarbon dating of archaeological squirrel remains; evidence of prehistoric human use of squirrels; and ancient DNA analysis of dated squirrel remains. Chirikof squirrels dated to at least 2000 years ago, and cut marks on squirrel bones suggested prehistoric use by people. Ancient squirrels also shared a mitochondrial haplotype with modern Chirikof squirrels. These results suggest that squirrels have been on Chirikof longer than previously assumed and that the current population of squirrels is closely related to the ancient population. Thus, it appears ground squirrels are not a recent, human-mediated introduction and may have colonized the island via a natural dispersal event or an ancient human translocation.

Archaeological evidence of validity of fish populations on unexploited reefs as proxy targets for modern populations.

Reef-fish management and conservation is hindered by a lack of information on fish populations prior to large-scale contemporary human impacts. As a result, relatively pristine sites are often used as conservation baselines for populations near sites affected by humans. This space-for-time approach can only be validated by sampling assemblages through time. We used archaeological remains to evaluate whether the remote, uninhabited Northwestern Hawaiian Islands (NWHI) might provide a reasonable proxy for a lightly exploited baseline in the Main Hawaiian Islands (MHI). We used molecular and morphological techniques to describe the taxonomic and size composition of the scarine parrotfish catches present in 2 archaeological assemblages from the MHI, compared metrics of these catches with modern estimates of reproductive parameters to evaluate whether catches represented by the archaeological material were consistent with sustainable fishing, and evaluated overlap between size structures represented by the archaeological material and modern survey data from the MHI and the NWHI to assess whether a space-for-time substitution is reasonable. The parrotfish catches represented by archaeological remains were consistent with sustainable fishing because they were dominated by large, mature individuals whose average size remained stable from prehistoric (AD approximately 1400-1700) through historic (AD 1700-1960) periods. The ancient catches were unlike populations in the MHI today. Overlap between the size structure of ancient MHI catches and modern survey data from the NWHI or the MHI was an order of magnitude greater for the NWHI comparison, a result that supports the validity of using the NWHI parrotfish data as a proxy for the MHI before accelerated, heavy human impacts in modern times.

Biodiversity of Holocene marine fish of the southeast coast of Brazil / Biodiversidade de peixes marinhos do Holoceno da costa Sudeste brasileira

Abstract Middens are archaeological sites dating between 8,000 and 1,000 years before present and are commonly found on the Brazilian coast. Data were collected from 68 middens allowing an inventory of 142 fish species, most of them recorded in no more than five sites. Conversely, Micropogonias furnieri and Pogonias cromis had the highest frequencies of occurrence. The biogeographic, ecological and economic data showed that most of the identified fish are widely distributed in the Western Atlantic (59.72%) and inhabit estuarine environments (53.99%), while most species have a demersal habit (35.92%) and exhibit oceanic migratory behaviour (28.87%). Lastly, the surveyed fish are predominantly carnivorous (72.54%) with some commercial value (96.48%). Chi-squared tests comparing midden inventory and current ichthyofauna checklists failed to show significant differences between them (p > 0.99). Thus, the results indicate that zoo-archaeological fish remains are key evidence of Holocene biodiversity and may help the establishment of more complete baselines.

Resumo Sambaquis são sítios arqueológicos, datando entre 8,000 e 1,000 anos antes do presente, encontrados na costa brasileira. Neste trabalho, dados ictiológicos referentes a 68 sambaquis da costa Sudeste do Brasil foram compilados e construído um inventário de referência no qual constam 142 espécies, a maioria das quais com registro em não mais que cinco sítios. Por outro lado, as espécies Micropogonias furnieri e Pogonias cromis apresentaram alta frequência de ocorrência nos sambaquis. Os dados biogeográficos, ecológicos e econômicos mostraram que a maioria das espécies registradas nos sambaquis são de ampla distribuição no Atlântico Ocidental (59.72%), habitam ambientes estuarinos (53.99%), tem um hábito demersal (35.92%) e comportamento oceânico migratório (28.87%). A maioria dos registros diz respeito a peixes carnívoros (72.54%) e com algum valor comercial (96.48%). A comparação da lista de ictiofauna registrada para os sambaquis com uma lista construída com base em inventários atuais de peixes para mesma região não mostrou diferenças significativas (teste de qui-quadrado, p> 0.99). Dessa forma, os resultados apresentados indicam que os vestígios de ictiofauna encontrados em sambaquis constituem uma amostra relevante da biodiversidade do Holoceno podendo ser muito úteis na construção de inventários de referências mais completos da fauna ictiológica da costa brasileira.