Climatic control of mat vegetation communities on inselberg archipelagos in south-eastern Brazil

Granite and/or gneiss inselbergs are excellent examples of geomorphologically stable island habitats, considered as old, climatically buffered, infertile landscapes (OCBILs). However, unlike oceanic islands, their underlying drivers of diversity patterns remain to be investigated. Here, we studied 24 inselbergs in south-eastern Brazil, aiming to understand the role of landscape variables and environmental conditions in the assembly of the characteristic extremophilic mat vegetation communities. We found that beta diversity was largely explained by climatic variables, whereas species richness did not vary among inselbergs. Classic determinants of the diversity of island communities do not generally seem to apply to these plant assemblages. Overall, these communities change along a coast-to-inland gradient that captures increased seasonality with a replacement of more hydrophilic taxa by more drought-tolerant taxa. Changes in species composition in space involved strong species replacement, with several widespread genera locally represented on distinct inselbergs by different narrowly distributed species. Despite the deterministic sorting of taxa based on climatic conditions, a substantial fraction of the beta diversity remained unexplained. This underlines the importance of historical processes, which are easier to notice in stable OCBIL regions, such as range expansion, local extinction, dispersal constraints and allopatric speciation.

Influence of roadkill during breeding migration on the sex ratio of land crab (Sesarma haematoche)

Adult land crabs generally live on land while their larvae live in the sea. In the case of Sesarma haematoche, female crabs migrate from land to sea to release the larvae at the high tide of syzygy night. Artificial structures along coastal areas are being obstacles for the migration of land crabs and causing synchronized roadkills on coastal roads during breeding migration. In this research, we compared the sex ratios of crab populations in coastal areas with coastal roads and uninhabited island areas with no road. The proportion of females in inland habitats with coastal roads was significantly smaller than island habitats. In particular, females are exposed to the risk of annually repeated roadkills, and the proportion of females decreases rapidly with their growth. If this tendency is general for land crab populations in the coastal areas with roads, significant road mortality of female land crabs during breeding migration can lead to severe population decline in coastal areas. Therefore, it is necessary to take an action to save land crabs crossing coastal roads.

Historical Ecology and Archaeology in the Galápagos Islands

Historical Ecology and Archaeology in the Galápagos Islands explores human history in the Galápagos Islands, which is today one of the world’s premier nature attractions. From its early beginnings, the Galápagos National Park connected a dual vision of biological conservation with responsible tourism. However, despite its popular perception as a pristine nature park, the archipelago has experienced protracted interactions with humans at least since its accidental discovery in 1535. This book contextualizes six years of interdisciplinary archaeological and historical research on San Cristóbal, the easternmost island in the archipelago. It focuses on the interior highland community of El Progreso and specifically the preserved vestiges of a 19th-century sugar plantation, the Hacienda El Progreso, which left the most intensive historic footprint of human activity in the islands. It did not do this alone, as other islands, particularly those with potable water sources, were varyingly impacted by human encounters. Proceeding within a framework of Historical Ecology, the book integrates archaeological research with historical and ecological study and incorporates three interconnected perspectives: 1. globalization and the increasing integration of the islands into an expanding network of human interests; 2. anthropogenic transformation of distinctive island habitats into novel or emerging ecosystems; and, 3. changing popular and scientific perceptions of nature and ecotourism’s role in biological conservation, preservation, and restoration.

Modeling Barrier Island Habitats Using Landscape Position Information

Barrier islands are dynamic environments because of their position along the marine–estuarine interface. Geomorphology influences habitat distribution on barrier islands by regulating exposure to harsh abiotic conditions. Researchers have identified linkages between habitat and landscape position, such as elevation and distance from shore, yet these linkages have not been fully leveraged to develop predictive models. Our aim was to evaluate the performance of commonly used machine learning algorithms, including K-nearest neighbor, support vector machine, and random forest, for predicting barrier island habitats using landscape position for Dauphin Island, Alabama, USA. Landscape position predictors were extracted from topobathymetric data. Models were developed for three tidal zones: subtidal, intertidal, and supratidal/upland. We used a contemporary habitat map to identify landscape position linkages for habitats, such as beach, dune, woody vegetation, and marsh. Deterministic accuracy, fuzzy accuracy, and hindcasting were used for validation. The random forest algorithm performed best for intertidal and supratidal/upland habitats, while the K-nearest neighbor algorithm performed best for subtidal habitats. A posteriori application of expert rules based on theoretical understanding of barrier island habitats enhanced model results. For the contemporary model, deterministic overall accuracy was nearly 70%, and fuzzy overall accuracy was over 80%. For the hindcast model, deterministic overall accuracy was nearly 80%, and fuzzy overall accuracy was over 90%. We found machine learning algorithms were well-suited for predicting barrier island habitats using landscape position. Our model framework could be coupled with hydrodynamic geomorphologic models for forecasting habitats with accelerated sea-level rise, simulated storms, and restoration actions.

Advancing barrier island habitat mapping using landscape position information

Barrier islands are dynamic ecosystems that change gradually from coastal processes, including currents and tides, and rapidly from episodic events, such as storms. These islands provide many important ecosystem services, including storm protection and erosion control to the mainland, habitat for fish and wildlife, and tourism. Habitat maps, developed by scientists, provide a critical tool for monitoring changes to these dynamic ecosystems. Barrier island monitoring often requires custom habitat maps due to several factors, including island size and the classification of unique geomorphology-based habitats, such as beach, dune, and barrier flats. In this study, we reviewed barrier-island-specific habitat mapping efforts and highlighted common habitat class types, source data, and mapping approaches. We also developed a framework for mapping geomorphology-based barrier island habitats using a rule-based, geographic object-based image analysis approach, which included the use of field data, tide data, high-resolution orthophotography, and lidar data. This framework integrates several barrier island mapping advancements with regard to the use of landscape position information for automated dune extraction and the use of Monte Carlo analyses for the treatment of elevation uncertainty for elevation-dependent habitats. Specifically, we used the uncertainty analyses to refine automated dune delineation based on elevation relative to extreme storm water levels and to increase the accuracy of intertidal and supratidal/upland habitat delineation. We found that dune extraction results were enhanced when elevation relative to storm water levels and visual interpretation were also applied. This framework could also be applied to beach–dune systems found along a mainland.

Investigating leaf beetles (Coleoptera, Chrysomelidae) on the west coast islands of Sabah via checklist-taking and DNA barcoding

Sabah is a province of Malaysia located on the northern part of the island of Borneo. Most of the leaf beetle fauna studies from this region conducted over the past 15 years have focussed on the mainland habitats while the leaf beetle fauna from island habitats (ca. 500 islands) have largely been overlooked. This study looks into the leaf beetle fauna of 13 small satellite islands off the west coast of Sabah. All specimens were first sorted into morpho-species operational taxonomic unit (OTU) before being identified to species rank where possible based on morphological characters and species names assigned when the specimens fitted the description of species in the literature. We collected 75 OTUs from 35 genera and five subfamilies according to morphology, 12 of which were identifiable to species level. In addition, the DNA barcode for each OTU was cross checked with records in GenBank and Barcoding of Life Data system (BOLD) to verify their identity. The number of species recorded was reduced from 12 species and 63 OTUs (total 75 OTUs) to 12 species and 56 OTUs (total 68 OTUs) after removal of the colour polymorphic species based on DNA barcode analyses. Pulau Gaya has the highest species richness and Pulau Sulug has the lowest species richness. A total of 64 Barcode Index Numbers consisting of 101 DNA barcodes were obtained from the 12 leaf beetle species and 48 OTUs. Based on the DNA barcode analyses, it was possible to confirm several polymorphic OTUs and cryptic species. The mean intraspecific and interspecific genetic divergence were determined as 0.77% and 16.11%, respectively. DNA barcodes of this study show a low similarity with records in GenBank and BOLD, highlighting the lack of representation and the urgency of studying leaf beetles from this region. The study provides the first documentation of leaf beetle fauna from island habitats of Sabah and the first DNA barcoding data for leaf beetles from this part of the world, with the next steps being larger scale sampling over a wider geographical scale for a better understanding of tropical arthropod diversity.