Tropical dry forest ecosystems are among the most endangered ecosystems globally. In Hawai‘i, dry forest species are under threat due to habitat destruction, invasive species, and a loss of mutualisms including pollinators. Understanding the pollination biology of species at risk can inform conservation strategies. This study aimed to identify the breeding system and types of floral visitors to Erythrina sandwicensis (Fabaceae) or wiliwili, an iconic Hawaiian tree in decline and with little regeneration. We conducted hand-pollination trials and observed visitors in two sites: a botanical garden and a forest site. We compared fruit set, seed set, seed germination, seedling growth rate, and seedling size across four pollination treatments: open control, autogamy, geitonogamy, and xenogamy. We found that wiliwili is visited by a novel suite of non-native visitors. All treatments produced seeds, but the xenogamous (cross) treatment produced significantly more fruit and seeds than the control or other treatments. Seedlings produced from cross-pollinated treatments were also taller and had wider basal diameters after twenty-eight days of growth. These results indicate that wiliwili employs a mixed-mating system, and that trees are pollen limited. Enhancing current populations of wiliwili to promote cross-pollination could help increase population regeneration.

Reports on the taxonomy and distribution of the amphipod crustacean Leucothoe nagatai , are discussed including significant range extensions from the type locality in the Sea of Japan. This research was based on existing museum specimens, and in situ collections of new material. Originally described from the branchial chamber of the solitary ascidian Styela plicata (), several new ascidian and sponges host species from California and New Zealand are documented for L. nagatai. Molecular studies confirm that northern and southern hemisphere populations are genetically indistinguishable. Color patterns in live and freshly preserved specimens of L. nagatai are diagnostic across its geographic range aiding in identification by nontaxonomists. Feeding habits of leucothoids within their invertebrate hosts are elucidated and discussed. Figures and plates of known invertebrate hosts, color patterns, and taxonomic structures are included.

This study documents all the currently known fish species from Wake Atoll, representing 98 families and 411 species. This paper updates the identifications of several previously reported unknown or undescribed species, revises the taxonomy from previous lists, and corrects errors and omissions. It builds on the past century of fish studies at this location, adding 43 families with 22 new reef species, 63 deep water species, and five pelagic species to the 321 species and 55 families previously recorded. The updated presence data is based on direct field observations by the author, reviews of all previous field observations for the past two decades, examination of data housed in academic institutions (voucher specimens), agency reports, and review of photographs and videos. In addition to being an active U.S. military installation, in 2009 the waters surrounding Wake Atoll became both a U.S. National Wildlife Refuge and a unit of the Pacific Remote Islands Marine National Monument. Anthropogenic influences and other factors that affect fish diversity and habitats are examined.

Visual census surveys utilizing a distance sampling approach were undertaken in Saipan Lagoon to determine the density of humphead wrasse (HHW) in four shallow water habitats, and compared to observations in the Saipan nighttime commercial spear fishery. Fish observed from the survey ranged in total length from 6.5 to 35 cm total length, generally smaller than the range of fish sampled from the commercial fishery of 16 to 47 cm total length. The majority of survey observations occurred in the central and northern part of Saipan Lagoon, which correlated with capture locations documented in the commercial fishery landings. Analysis of contemporary and historical commercial fishery data showed that HHW could not be considered primary fishery target species. Distance sampling results indicated that coral/hard bottom and Enhalus acroroides seagrass were the habitats most important to HHW, as reflected by higher density estimates. The use of distance sampling was useful in estimating the spatial distribution and density of HHW, and should be considered when assessing other rare marine finfish species.

Hylaeus anthracinus is an endemic Hawaiian yellow-faced bee (Colletidae) that is federally protected under the Endangered Species Act of 1973. On O‘ahu, H. anthracinus populations are restricted to a few isolated areas of intact coastal strand habitat. A detailed understanding of H. anthracinus nesting ecology is required to protect and expand the remaining fragmented and isolated populations. Here, we explore how nest parameters such as tunnel inside diameter, cell length, cell partition material, and plant species utilization compare among H. anthracinus and three non-native coastal bee species. Solitary bee nests from coastal habitats on O‘ahu, Hawai‘i were dissected and nest parameters were measured, compared, and described. We found overlap in most nest parameters among H. anthracinus and the introduced species: Hylaeus strenuus, Ceratina smaragdula, and Ceratina dentipes. No significant differences for inside diameter of nest entrance, length of tunnel nest, or # of cells/nest were found among the four bee species that were utilizing cavity nests. Thus, competition for nesting resources could be occurring. This increased understanding of H. anthracinus nest ecology will inform future conservation actions that could include the development of captive rearing programs, translocations, use of artificial nest sites, and the enhancement of natural habitat to increase nesting resources to support the existing populations.

Invertebrates are key to island ecosystems but impacts from invasive mammalian predators are not well documented or understood. Given this knowledge gap, we studied terrestrial arthropod communities in the presence of a common invasive rodent (house mice, Mus musculus) on a subtropical atoll—Midway Atoll National Wildlife Refuge (MANWR). Here, invasive mice recently began to attack and depredate nesting seabirds, prompting planning for a future mouse eradication. However, uncertainty remains regarding the ecosystem's response to mouse removal. As part of a pre-eradication investigation, we conducted a baseline survey of MANWR's arthropod community structure and diversity (at order level), comparing islands with and without mice. From April 2018 to February 2020, we used pitfall traps to monitor ground-dwelling arthropods on MANWR's Sand Island (mice present) and Eastern Island (mice absent). During our study, we captured over 450,000 specimens from 24 taxonomic units. Arthropods on MANWR form six community clusters and differ between islands and habitats. Richness is relatively similar among clusters and islands, but diversity of common and dominant arthropod taxa is significantly higher on Sand Island, as well as in anthropogenically-built habitats. Weather is not a strong environmental driver of arthropod communities; community structure and diversity vary only slightly throughout the year. Additionally, anthropomorphic landscape-level alteration of MANWR may still influence arthropod communities today. Continued monitoring and research will provide better insight into how arthropod communities recover following invasive mouse eradications. Our study contributes to the body of knowledge of arthropods in the Northwestern Hawaiian Islands, arthropod community ecology, and potential mouse impacts on islands.

There is little known about cetaceans in the waters of Papua New Guinea (PNG). Here we present findings from the first two sets of cetacean sighting and acoustic surveys conducted within the Admiralty Island group in the northern Bismarck Sea. More than 1,000 cetaceans were sighted during our boat-based surveys–the most common being spinner dolphins (Stenella longirostris), followed by pantropical spotted dolphins (Stenella attenuata), short-finned pilot whales (Globicephala macrorhynchus), and sperm whales (Physeter macrocephalus). The relative group size of spinner dolphins was different between years with group sizes in 2010 being significantly lower (median = 15, range = 2–50) than those recorded in 2013 (median = 50, range = 5–100). The presence of large aggregations of spinner dolphins (including calves) as well as sightings of Vulnerable sperm whales suggest the northern Bismarck Sea as an area of conservation importance for cetaceans. Our surveys also provide useful baseline data for a variety of marine protected area planning processes and management initiatives that are ongoing in PNG.

Remote oceanic islands have high potential to harbor unique fauna and flora, but opportunities to conduct in-depth biotic surveys are often limited. Furthermore, underrepresentation of existing biodiversity in the literature has the potential to detract from conservation planning and action. Between 18 and 29 October 2018, we surveyed the terrestrial vertebrates of East Rennell, a UNESCO World Heritage Site in Solomon Islands. We documented 56 species, including 15 squamates, 13 mammals, and 38 birds, and present four new vertebrate records for the island: Stephan's emerald dove (Chalcophaps stephani), Maluku myotis (Myotis moluccarum), littoral skink (Emoia atrocostata) and brahminy blindsnake (Indotyphlops braminus). East Rennell was designated a World Heritage site for its significant on-going ecological and biological processes, and importance for the study of island biogeography. The new records presented here provide evidence that continued field studies combined with DNA analysis will continue to uncover even greater endemic biodiversity. Rennell is currently experiencing major habitat destruction in parts of the island that are not under World Heritage protection, and we anticipate collateral damage will likely extend into protected areas. Our survey also underscores the incredible vertebrate biodiversity that stands to be lost unless conservation actions and local community needs are intertwined to promote beneficial outcomes on both fronts.

While the influence of elevation and seasonal variation on isotopic composition has been studied on Maui, Hawai‘i Island, and O‘ahu (, , , , , ), this work is the first to investigate event-based precipitation in detail on the island of O‘ahu. The stable isotopic composition of water has been used to track the movement of water within the hydrosphere, to investigate the type and origin of a rainfall event, and elevation of collection, among other characteristics. Here, we present a high-resolution study of the stable isotopes δ²H and δ¹⁸O of precipitation along a compact land-to-sea transect in Waikīkī, a southwest facing region on O‘ahu. The study provides a unique, in-depth investigation into the nature of individual storm events, and how they contribute to a larger seasonal climatic pattern. Monthly precipitation samples were collected at three sites along the transect from December 2017 to March 2019 and event-based samples were collected at the Makai site from October 2018 to February 2019. Storm direction, temperature, and relative humidity were recorded for each event-based sample. Results suggest that evaporative conditions at different elevations influence the isotopic composition of precipitation, either through net addition as moisture recycling, or net loss of evaporated water. The spatial distribution of these patterns from site to site illustrates the extreme heterogeneity of Hawaiian watersheds.