Deriving robust historical population trends for long-lived species subject to human exploitation is challenging in scenarios where long-term scientific data are scarce or unavailable, as often occurs for species affected by small-scale fisheries and subsistence hunting. The importance of Local Ecological Knowledge (LEK) in data-poor scenarios is increasingly recognized in conservation, both in terms of uncovering historical trends and for engaging community stewardship of historic information. Building on previous work in marine historical ecology and local ecological knowledge, we propose a mixed socio-ecological framework to reliably document and quantify LEK to reconstruct historical population trends. Our method can be adapted by interdisciplinary teams to study various long-lived taxa with a history of human use. We demonstrate the validity of our approach by reconstructing long-term abundance data for the heavily-exploited East Pacific green turtle (Chelonia mydas) in Baja California, Mexico, which was driven to near extinction by a largely unregulated fishery from the early 1950s to the 1980s. No scientific baseline abundance data were available for this time-frame because recent biological surveys started in 1995 after all green turtle fisheries in the area were closed. To fill this data gap, we documented LEK among local fishers using ethnographic methods and obtained verified, qualitative data to understand the socio-environmental complexity of the green turtle fishery. We then established an iterative framework to synthesize and quantify LEK using generalized linear models (GLMs) and nonlinear regression (NLR) to generate a standardized, LEK-derived catch-per-unit-effort (CPUE) time-series. CPUE is an index of abundance that is compatible with contemporary scientific survey data. We confirmed the accuracy of LEK-derived CPUE estimates via comparisons with fisheries statistics available for 1962–1982. We then modeled LEK-derived abundance trends prior to 1995 using NLR. Our model established baseline abundance and described historical declines, revealing that the most critical (exponential) decline occurred between 1960 and 1980. This robust integration of LEK data with ecological science is of critical value for conservation and management, as it contributes to a holistic view of a species’ historic and contemporary conservation status.

The application of special scanning technologies in plant population studies makes it now possible to offer reliable indirect estimations of Leaf Area Index (LAI). This has stimulated the adaptation of related biomass assessment methods and has provided a way to simplify tedious laboratory procedures whilst avoiding destructive sampling. Particularly, aboveground biomass for Zostera marina L. has been expressed depending linearly on Leaf Area Index. Nevertheless, we demonstrate that this approach produces biased estimations. It is also shown that expressing leaf dry weight by means of an allometric function of length and width can eliminate bias. Furthermore, the dominant term of the associated power series expansion becomes the aforementioned linear representation in terms of Leaf Area Index. The consistency of the estimation methods derived from the allometric model was tested using data from a Z. marina meadow. Consequently, the improved method is expected to become a valuable tool for the reduction of the uncertainty associated with the estimation of above‐ground biomass through the use of Leaf Area Index.

Estimation of leaf productivity in eelgrass (Zostera marina L.) is crucial for evaluating the ecological role of this important seagrass species. Although leaf marking techniques are widely used to obtain estimates of leaf productivity, the accuracy of these assessments, has been questioned mainly because these fail to account for leaf growth bellow the reference mark and also because they apparently disregard the contribution of mature leaf tissues to the growth rate of leaves. On the other hand, the plastochrone method is a simpler technique that has been considered to effectively capture growth in a more realistic way, thereby providing more accurate assessments of both above- and below-ground productivities. But since the actual values of eelgrass growth rates are difficult to obtain, the worth of the plastochrone method has been largely vindicated because it produces assessments that overestimate productivity as compared to estimates obtained by leaf marking. Additionally, whenever eelgrass leaf biomass can be allometrically scaled in terms of matching leaf length in a consistent way, the associated leaf growth rates can be also projected allometrically. In this contribution, we used that approach to derive an authentication of the plastochrone method and formally demonstrate that, as has been claimed to occur for leaf marking approaches, the plastochrone method itself underestimates actual values of eelgrass leaf growth rates. We also show that this unavoidable bias is mainly due to the inadequacy of single-leaf biomass assessments in providing a proxy for the growth of all leaf tissue in a shoot over a given interval. Moreover, the derived formulae give conditions under which assessments of leaf growth rates using the plastochrone method would systematically underestimate matching values obtained by leaf marking procedures. And, assessments of leaf growth rates obtained by using the present data show that plastochrone method estimations underestimated corresponding proxies obtained allometrically (27%), or through leaf marking (35%). Allometric projection is recommended as a simpler and more effective procedure to reduce the bias in eelgrass leaf productivity estimations that associates to the use of plastochrone methods.

El objetivo de este trabajo fue caracterizar la variabilidad espaciotemporal de clorofila satelital (Clsat), productividad primaria (PP), temperatura de la superficie del mar (TSM) y altura del nivel del mar (ANM) de julio de 2002 a diciembre de 2018 en el banco de Campeche. Se descargaron composiciones mensuales de Clsat y TSM del sensor MODIS-Aqua, y de ANM de la página COPERNICUS. Las composiciones de PP se descargaron de la página de internet de la Universidad Estatal de Oregón. Se estudiaron 4 transectos de 200 km perpendiculares a la costa de Campeche (T1 a T4), y 1 de 300 km paralelo a la misma (T5). Se construyeron series de tiempo y diagramas Hovmöller para estudiar las variaciones espaciales y temporales. La Clsat en T1 a T4 mostró una distinción entre una zona interior (0–60 km) y una exterior (60–200 km). La zona nerítica interior presentó los máximos de Clsat (>2.5 mg·m–3) y PP (>2 g C·m–2·d–1) en época de lluvias y los mínimos en época de secas (<0.25 m) en época de secas (<2 mg·m–3 y 0.6 mg·m–3) y PP (>0.7 g C·m–2·d–1) durante los frentes fríos y los mínimos en secas (<0.3 mg·m–3 y 30 °C) en época de lluvias y mínimos (<22 ºC) durante frente fríos; la ANM tuvo máximos (0.40 m) durante frentes fríos y mínimos (<0.25 m) en época de secas.