Tropical Habitats Research Articles

Serum vitamin D in sanctuary chimpanzees (Pan troglodytes) in range countries: A pilot study.

Vitamin D is essential for skeletal health, calcium homeostasis and general health. The major and more stable form of vitamin D in circulation is 25-hydroxyvitamin D (25-OH-D); this is the most valuable indicator of vitamin D status. There are studies on laboratory and zoo-housed chimpanzees; however, serum vitamin D status has not been documented in chimpanzees in range countries. (1) Determine the range of circulating 25-OH-D concentrations in chimpanzees in range countries. (2) Assess the influence of age, sex, and sun exposure on 25-OH-D serum concentrations. Opportunistic blood samples were obtained from 127 clinically healthy chimpanzees. Serum 25-OH-D concentration was measured with a commercially available competitive ELISA. The median overall 25-OH-D concentration for chimpanzees in range countries was 46.24nmol/L (range: 17.10-109.23nmol/L). Males had a significantly lower concentration (40.15nmol/L) than females (49.61nmol/L), and infants (37.99nmol/L) had a significantly lower concentration than adults (46.04nmol/L). Concentrations of 25-OH-D in chimpanzees in sunnier habitats were significantly higher compared to thick tropical forest habitat. The present constitutes a large dataset of serum 25-OH-D concentrations in range country sanctuary chimpanzees and contributes to document normal ranges. Age, sex, and sun exposure influenced serum concentrations of 25-OH-D in sanctuary chimpanzees.

Vegetative fragment production as a means of propagule dispersal for tropical seagrass meadows

Background and aimsLong distance dispersal (LDD) contributes to the replenishment and recovery of tropical seagrass habitats exposed to disturbance, such as cyclones and infrastructure development. However, our current knowledge regarding the physical attributes of seagrass fragments that influence LDD predominantly stems from temperate species and regions. The goal of this paper is to measure seagrass fragment density and viability in two tropical species, assessing various factors influencing their distribution. MethodsWe measured the density and viability of floating seagrass fragments for two tropical seagrass species (Zostera muelleri and Halodule uninervis) in two coastal seagrass meadows in the central Great Barrier Reef World Heritage Area, Australia. We assessed the effect of wind speed, wind direction, seagrass growing/senescent season, seagrass meadow density, meadow location and dugong foraging intensity on fragment density. We also measured seagrass fragment structure and fragment viability; i.e., potential to establish into a new plant. Key resultsWe found that seagrass meadow density, season, wind direction and wind speed influenced total fragment density, while season and wind speed influenced the density of viable fragments. Dugong foraging intensity did not influence fragment density. Our results indicate that wave action from winds combined with high seagrass meadow density increases seagrass fragment creation, and that more fragments are produced during the growing than the senescent season. Seagrass fragments classified as viable for Z. muelleri and H. uninervis had significantly more shoots and leaves than non-viable fragments. We collected 0.63 (±0.08 SE) floating viable fragments 100 m−2 in the growing season, and 0.13 (±0.03 SE) viable fragments 100 m−2 in the senescent season. Over a third (38%) of all fragments collected were viable. ConclusionThere is likely to be a large number of viable seagrass fragments available for long distance dispersal. This study's outputs can inform dispersal and connectivity models that are used to direct seagrass ecosystem management and conservation strategies.

The Lignicolous Genus Entonaema: Its Phylogenetic–Taxonomic Position within Hypoxylaceae (Xylariales, Fungi) and an Overview of Its Species, Biogeography, and Ecology

The lignicolous saprotrophic genus Entonaema contains six formally accepted species: E. liquescens (type species), E. cinnabarinum, E. globosum, E. dengii, E. moluccanum, and E. siamensis. Its stromatic ascomata develop on the surface of dead wood remnants; they are rather large, globose to irregularly shaped, and vividly coloured. The fresh stroma interior is filled with a liquid matter. In early studies, the genus was considered to have a preference for tropical habitats, while in more recent field research, numerous collections have been added from warm, temperate areas of Europe, North America, and Asia. Our taxonomic and phylogenetic studies were based on freshly collected E. cinnabarinum from Croatia and E. liquescens from the USA. A phylogenetic study of the sequence alignment of four concatenated gene regions (ITS, LSU, rpb2, and β-tub) revealed the true taxonomic position of Entonaema within Hypoxylaceae (Xylariales), a sister to Hypoxylon carneum. Detailed macroscopic and microscopic descriptions of E. cinnabarinum are accompanied by drawings and colour photographs, while the study of E. liquescens is focused on stromatal microchemical reaction. With new information, the worldwide identification key to the putative species of Entonaema is proposed. Ecological data and biogeographical patterns were studied using all available and reliable sources of recorded data. Climatic preferences of the two most widespread Entonaema species, E. liquescens and E. cinnabarinum, are discussed in detail.

Distributional range shifts of Western Atlantic benthic Sargassum species (Fucales, Phaeophyceae) under future climate change scenarios

Climate change is altering the world’s marine biota, in particular, their geographic distribution. Sargassum species are foundation species that play critical ecological roles in tropical benthic communities, providing food, habitat heterogeneity and shelter for a wide range of marine organisms. To understand how future changes in abiotic variables could affect the distribution of Sargassum species along the Western Atlantic Ocean, we performed Ecological Niche Models (ENM) for 12 benthic Sargassum species. We projected present and future habitat suitability distributions under the RCP 4.5 and RCP 8.5 IPCC scenarios. We fit ENM and created ensembles from different algorithms. Our results predict changes in species latitudinal range (niche suitability) in the order of 0.5˚ to 8.1˚ northward, and 0˚ to 5.5˚ southward. Six species are likely to reduce their suitability area from 10% to 80%, while other six species are likely to expand their suitability area from 4% to 168%. Overall, changes in suitability area and latitudinal ranges will increase at larger latitudes for most species while suitability areas will decrease at lower latitudes for half of the species. This pattern is consistent with the expected tropicalization of temperate latitudes following global warming. Such changes can produce considerable losses in ecosystem services maintained by healthy Sargassum beds, particularly at lower latitudes. Our findings highlight the need to improve Sargassum conservation policies and management strategies to avoid the negative effects caused by losses in Sargassum forests.

Living on the edge: forest edge effects on microclimate and terrestrial mammal activity in disturbed lowland forest in Sumatra, Indonesia

AbstractSpecies–environment relationships are often studied at large spatial scales, but effective conservation requires an understanding of local-scale environmental drivers and pressures. Widespread degradation and fragmentation of forests have increased the proportion of tropical mammal habitat that is affected by edge effects. Edge effects include greater exposure to anthropogenic disturbance and abiotic changes that synergistically influence how well populations can cope with climate change. We investigated relationships between distance to the forest edge, forest structure, microclimate and terrestrial mammal detections in a selectively logged forest at the boundary of Gunung Leuser National Park in Sumatra, Indonesia. We collected mammal detection data from motion-activated camera traps, microclimate data from automated climate data loggers and forest structure data from vegetation plots. Daily mean and maximum temperatures significantly decreased with distance from the forest edge, whereas tree height and minimum temperature increased. Mammal diversity was lower at the forest edge compared to the interior. Mammals were detected less frequently at the forest edge, although this relationship varied between mammal orders. Mammal detections were best explained by temperature, tree height and tree diameter at breast height. These results demonstrate that abiotic changes in forests brought on by edge effects have negative impacts on mammals, but these effects vary between mammal taxa because of differing sensitivities to human disturbance. Our findings highlight the importance of considering local-scale environmental drivers in determining species–environment relationships to identify key habitat features such as microclimate refuges that should be prioritized in ecosystem management.

Conservation planning in national parks may benefit from site occupancy and detection estimates of native animal species

Protected areas are the best strategy to conserve native biodiversity around the world. In Southeast Asia, most of the pristine tropical forest habitats are limited to terrestrial protected areas such as national parks and wildlife reserves. Endau Rompin National Park (ERNP) is one of undisturbed biodiversity-hotspots in the southern region of Peninsular Malaysia but surrounded by industrial oil palm plantations and threatened by habitat fragmentation. To date, little is known about the distribution and habitat requirement of wildlife, including those conservation priority species in the ERNP. This study aims to investigate the mammal distribution in the ERNP by estimating the probability of occurrence of a species among sampled sites. At 24 camera-trapping sites, we used passive infrared camera traps to detect the forest wildlife. We estimated wildlife occupancy by using single-season occupancy analysis while considering of imperfect detection and relating it to stand- and landscape-level variables. We detected 26 species of native wild animals in the study area including several conservation priority species such as Asian elephant, Asian tapir, and Malayan tiger. The site occupancy of conservation-priority species attests to ERNP's status as an important regional biodiversity hotspot. The detection probabilities of wildlife species were highly sensitive to specific ecological variables at stand- and landscape-level. Our data indicated that tree canopy cover, forest edges, adjacent human settlements, and riparian habitats (e.g., stream and river) are crucial for the persistence of the native wildlife species. Our results suggest that pristine forest habitat such as those typical to the ERNP are critical for wildlife conservation. We suggest that the stand- and landscape-level ecological variables are considered in the conservation planning to protect the forest biodiversity and ecological integrity of the national park and other terrestrial protected areas in the tropics.

A seafloor sensitivity index to oil spills in tropical marine protected areas

Oil spills are a global environmental challenge with ecological impacts at local and regional scales. In 2019, a major oil spill from an unknown source reached the Brazilian margin and strongly affected tropical marine habitats with high biodiversity. It is therefore important to establish a quick and accessible approach to assist decision-makers for oil spill responses. Based on current Brazilian legislation, only very specific companies (such as organized ports, port facilities, platforms and their auxiliary facilities) are obliged to maintain marine oil spill response structures. This paper aims to develop an approach for mapping seafloor sensitivity to oil spills for continental shelf areas with limited resources and materials. The study was conducted using a pre-existing bathymetric dataset, at mega- and meso-habitat scales. The assessed area extends over 933 km2, between the 10 and 90 m isobaths, comprising tropical marine areas of intense maritime traffic due to the strategic location for important international routes and also due to the presence of ports, terminals and shipyards. From the megahabitat-scale analyses (30 m resolution grid), the areas with greatest topographic complexity were selected for subsequent detailed analysis and the development of a seafloor sensitivity index at a mesohabitat-scale (10 m resolution grid). The results revealed that 12.7% of the area was classified at a high seafloor sensitivity index (SIseafloor), 28.7% was classified at relatively moderate sensitivity, and 58% was classified at low sensitivity. The seafloor sensitivity methodology presented here can be easily applied to other locations to prepare recovery operations, monitoring plans, and for other forms of environmental planning.

Assessing Pleistocene–Holocene climatic and environmental change in insular Near Oceania using stable isotope analysis of archaeological fauna

ABSTRACTIn comparison to temperate and arid regions, environmental responses to the Last Glacial Maximum and the Terminal Pleistocene and Holocene boundary remain poorly known for many parts of the tropics, making it challenging to unravel human–landscape interactions across this timeframe. This is particularly the case in insular Near Oceania, where sea‐level fluctuations and potential changes in forest cover may have had major impacts on hunter–gatherer populations. Here, we apply stable carbon and oxygen isotope analyses to small‐mammal teeth from four Pleistocene–Holocene (spanning from 29 000 years ago to the late Holocene) sequences in the Bismarck Archipelago to reconstruct changes in environments directly exploited by human populations in this part of the world. Our results show a subtle response of tropical habitats in Near Oceania to relatively arid conditions during the late‐glacial period, something that has also been observed at sites in South and Southeast Asia, followed by a Terminal Pleistocene–Holocene expansion of tropical forest cover. Nevertheless, site‐based variability in environmental responses across this period highlight the need for more multidisciplinary studies of human occupation sequences in a region that is becoming increasingly central to exploring human adaptations, environmental modifications and social network development over the past 20 000 years.

Eukaryotic algal community composition in tropical environments from solar salterns to the open sea

Tropical environments with unique abiotic and biotic factors—such as salt ponds, mangroves, and coral reefs—are often in close proximity. The heterogeneity of these environments is reflected in community shifts over short distances, resulting in high biodiversity. While phytoplankton assemblages physically associated with corals, particularly their symbionts, are well studied, less is known about phytoplankton diversity across tropical aquatic environments. We assess shifts in phytoplankton community composition along inshore to offshore gradients by sequencing and analyzing 16S rRNA gene amplicons using primers targeting the V1-V2 region that capture plastids from eukaryotic phytoplankton and cyanobacteria, as well as heterotrophic bacteria. Microbial alpha diversity computed from 16S V1-V2 amplicon sequence variant (ASV) data from 282 samples collected in and around Curaçao, in the Southern Caribbean Sea, varied more within the dynamic salt ponds, salterns, and mangroves, compared to the seemingly stable above-reef, off-reef, and open sea environments. Among eukaryotic phytoplankton, stramenopiles often exhibited the highest relative abundances in mangrove, above-reef, off-reef, and open sea environments, where cyanobacteria also showed high relative abundances. Within stramenopiles, diatom amplicons dominated in salt ponds and mangroves, while dictyochophytes and pelagophytes prevailed above reefs and offshore. Green algae and cryptophytes were also present, and the former exhibited transitions following the gradient from inland to offshore. Chlorophytes and prasinophyte Class IV dominated in salt ponds, while prasinophyte Class II, including Micromonas commoda and Ostreococcus Clade OII, had the highest relative abundances of green algae in mangroves, above-reef, off-reef, and the open sea. To improve Class II prasinophyte classification, we sequenced 18S rRNA gene amplicons from the V4 region in 41 samples which were used to interrelate plastid-based results with information on uncultured prasinophyte species from prior 18S rRNA gene-based studies. This highlighted the presence of newly described Ostreococcus bengalensis and two Micromonas candidate species. Network analyses identified co-occurrence patterns between individual phytoplankton groups, including cyanobacteria, and heterotrophic bacteria. Our study reveals multiple uncultured and novel lineages within green algae and dictyochophytes in tropical marine habitats. Collectively, the algal diversity patterns and potential co-occurrence relationships observed in connection to physicochemical and spatial influences help provide a baseline against which future change can be assessed.

Two new spotted species of the Cyrtodactylus (Geckoella) collegalensis (Beddome, 1870) complex from the south-eastern coast of India (Reptilia: Squamata)

We describe two new spotted species of ground-dwelling gecko of the genus Cyrtodactylus (Geckoella) from southeastern India in an integrative taxonomic framework. The new species are recovered as sister taxa within the C. collegalensis species complex, with 13.0–16.7% uncorrected mitochondrial sequence divergence from the other eight members of the C. collegalensis complex and 10.4% from one another. The new species are morphologically diagnosed by a spotted dorsal pattern of four pairs of spots (occasionally fused into figure 8-shaped markings) from the banded species C. aravindi, C. speciosus, C. rishivalleyensis and C. yakhuna; and from the spotted species with three or fewer pairs of spots in C. collegalensis and C. srilekhae; and from C. chengodumalaensis by the absence of any enlarged dorsal scales and from C. varadgirii by the absence of a patch of enlarged roughly hexagonal scales on the canthus rostralis and beneath the angle of the lower jaw. The two new species can only be differentiated from each other based on slight differences in body size, relative body width and other statistically significant, size-corrected morphometric characters. These are among the first endemic lizards from Tropical Dry Evergreen habitats along the southeast coast of India.

Thallium toxicity to temperate and tropical marine organisms: Derivation of water quality guidelines to protect marine life

A lack of thallium (Tl) toxicity data for marine organisms has hampered the development of water quality guidelines for protecting marine life and assessing ecological hazard/risk. This study assessed the toxicity (EC10/EC50) of Tl in natural seawater (salinity 34 psu and pH 8.05) to 26 functionally diverse marine organisms (19 phyla from five trophic levels) from a variety of temperate and tropical coastal marine habitats. EC10 values ranged from 3.0 μg/L (copepod, Acartia tranteri) to 489 μg/L (cyanobacterium, Cyanobium sp.), while EC50 values ranged from 9.7 μg/L to 1550 μg/L. Thallium(I) was the dominant (86–99 %) oxidation state in test waters across the range of EC10 and EC50 values. Thallium toxicity (EC10/EC50) did not differ between temperate and tropical marine organisms. New, reliable, long-term Tl water quality guidelines were derived using species sensitivity distributions (with model-averaging) to protect marine life in Australia (e.g., 3.9 μg/L for 95 % species protection).

Temporal modelling of Lymnaea natalensis (Krauss, 1848) in tropical aquatic habitats.

Lymnaea natalensisis the only snail intermediate host ofFasciola gigantica, the causative agent of fascioliasis, in Nigeria. The species also serves as intermediate host for many other African trematode species of medical and veterinary importance, and it is found throughout the country. However, there is no detailed information on the factors that influence its distribution and seasonal abundance in the tropical aquatic habitats in Nigeria. This study used the geographic information system and remotely sensed data to develop models for predicting the distribution ofL. natalensisin South-Western Nigeria. Both land surface temperature (LST) and normalised difference vegetation index (NDVI) were extracted from Landsat satellite imagery; other variables (slope and elevation) were extracted from a digital elevation model (DEM) while rainfall data were retrieved from the European Meteorology Research Programme (EMRP). These environmental variables were integrated into a geographic information system (GIS) to predict suitable habitats ofL. natalensisusing exploratory regression. A total of 1410L. natalensissnails were collectedvis-à-vis22 sampling sites. Built-up areas recorded moreL. natalensiscompared with farmlands. There was no significant difference in the abundance of snails with season (p 0.05). The regression models showed that rainfall, NDVI, and slope were predictors ofL. natalensisdistribution. The habitats suitable forL. natalensiswere central areas, while areas to the north and south were not suitable forL. natalensis.Contribution:The predictive risk models ofL. natalensisin the study will be useful in mapping other areas where the snail sampling could not be conducted.

Effects of projected end-of-century temperature on the muscle development of neonate epaulette sharks, Hemiscyllium ocellatum

Epaulette sharks (Hemiscyllium ocellatum) inhabit shallow tropical habitats with elevated and fluctuating temperatures. Yet, according to global climate change projections, water temperatures in these habitats will rise beyond current cyclical variability, warranting further studies incorporating chronically elevated temperature exposure in this species. This study examined the differences in skeletal muscle morphological and metabolic properties in neonate epaulette sharks exposed to their current-day ambient (27 °C) or projected end-of-century (31 °C) habitat temperatures throughout embryonic and neonatal development. Metrics of skeletal muscle, such as muscle fiber size and density, nuclear density, and satellite cell density, were used to assess the relative contribution of hypertrophic and hyperplastic growth processes. Capillary density was measured as a proxy for peripheral oxygen supply to muscle tissue. At 31 °C, sharks hatched earlier, but were similar in body size 60 days post-hatch. Muscle fiber size, nuclear density, and capillary density were similar between temperature regimes. However, fiber density was lower, satellite cell density was higher, and fibers associated with satellite cells were smaller in sharks reared at 31 °C. These results suggest that elevated temperature may impair or slow satellite cell fusion to existing fibers and new fiber formation. To assess potential metabolic and developmental consequences of elevated temperatures, oxidative damage (2,4-DNPH, 8-OHdG, 4-HNE), protein degradation (Ubiquitin, LC3B, Hsp70), and muscle differentiation (Myf5, Myogenin) markers were measured. Protein carbonylation was higher at elevated temperatures, suggesting that warmer incubation temperatures at early life stages may result in oxidative damage accrual. However, protein degradation and muscle differentiation markers did not differ. These results suggest that projected end-of-century temperatures may alter muscle growth and metabolism in tropical shark species with potential consequences to shark growth and fitness.

Late Pleistocene to late Holocene palaeoecology and human foraging at Kuumbi Cave, Zanzibar Island

BackgroundClimate change played a major role in shaping regional human-environment interactions in Africa during the late Pleistocene-Holocene, but this topic has not been exhaustively studied, particularly in eastern Africa. While there is growing evidence that the coastal and island settings in this region played a critical role in human evolution, combined archaeological and palaeoenvironmental studies have tended to focus on the arid interior and show the dominance of grasslands with patches of closed and open woodlands during the last 20,000 years.MethodsHere, we present stable carbon and oxygen isotope analyses of zooarchaeological remains (n = 229) recovered from Kuumbi Cave, Zanzibar Island, spanning the last glacial period and the Holocene (20,000 to 500 cal. BP).ResultsOur data demonstrate that the vicinity of Kuumbi Cave was consistently covered by mosaic habitats, dominated by forests and small patches of open woodland and grassland. The inhabitants of Kuumbi Cave exploited these diverse tropical habitats even after the regional arrival of agriculture.DiscussionWe suggest that the stable coastal forest mosaic habitats acted as a refugium for foragers during glacial periods and that the Iron Age inhabitants of Kuumbi Cave were not food producers migrating from the interior, but rather Indigenous foragers interacting with food production.

Stinkbird Has a Superpower by Jill Esbaum (review)

Reviewed by: Stinkbird Has a Superpower by Jill Esbaum Danica Ronquillo Esbaum, Jill Stinkbird Has a Superpower; illus. by Bob Shea. Putnam, 2023 [32p] Trade ed. ISBN 9780593529522 $18.99 E-book ed. ISBN 9780593529539 $10.99 Reviewed from digital galleys R* 5-9 yrs Deep in the Amazon rainforest, an Amazonian hoatzin ("You can say it—WHOT-sin. Handsome, aren't I?"), or the stinkbird, cheerfully informs the reader that while they share traits with common birds, like wings, feathers, and a beak, stinkbirds also have a hidden superpower. Before he can reveal what that superpower is exactly, his curious and anxious son constantly interrupts him with questions about what it could be. From there, the father hoatzin takes his son all over the rainforest, sharing stinkbird facts with both the reader and his son: the nickname "Stinkbird'' is due to the bird's poopy smell; they have a loud and beautiful song; and hoatzin chicks' escape from predators by jumping out of their nests and swimming in the river. This comical picture book about the Amazonian hoatzin swoops in to delight readers with funny facts, and Shea's smooth and textural digital illustrations and eye for composition effectively create a child-like stinkbird perspective. Viewers are immersed in predominant shades of green in the tropical habitat, while fiery orange stinkbird dad and his grape-purple son take center stage. The father's educational narration pairs with bantering dialogue in the speech bubbles to portray a loving relationship between father and son. Young animal lovers will look forward to following more of Esbaum and Shea's collaborations in their upcoming animal picture book series. End matter includes an entertaining true and false page about the Amazonian hoatzin from the Cornell Lab of Ornithology. Copyright © 2023 The Board of Trustees of the University of Illinois

Abundance and distributional ecology of cetaceans in the central Philippines

In general, little is known about cetacean abundance and distribution in Southeast Asia. This paper investigates the species composition, interactions/associations, abundance and distribution of cetaceans in an archipelagic tropical habitat characterised by deep, oceanic waters approaching the shore, high water temperatures and deep, stable thermoclines. Abundance is estimated using line transect methods. In addition, the cetacean fauna of the Sulu Sea is compared with those of other tropical marine ecosystems: the eastern tropical Pacific, the western Indian Ocean and the Gulf of Mexico. The most abundant species in the two study sites (eastern Sulu Sea and the Tañon Strait) was the spinner dolphin, Stenella longirostris; with a population estimate of 31,512 (CV=26.63%) in the eastern Sulu Sea and 3,489 (CV=26.47%) in the Tañon Strait. Other abundant species were the pantropical spotted dolphin (S. attenuata), Fraser’s dolphin (Lagenodelphis hosei) and the short-finned pilot whale (Globicephala macrorhynchus). Density and species-abundance rank varied between the two study sites, with generally higher densities in the Sulu Sea than in the Tañon Strait. An exception was the dwarf sperm whale, Kogia sima, whose density was 15 times higher in the Tañon Strait. Fraser’s dolphin ranked third in abundance in the Sulu Sea but was absent from the Tañon Strait. Environmental factors such as depth, site and temperature were observed to have a significant influence on the distributions of various species.

Climate warming erodes tropical reef habitat through frequency and intensity of episodic hypoxia

Climate warming threatens marine life by increasing metabolic oxygen demand while decreasing oxygen availability. Tropical species living in warm, low oxygen environments may be most at risk, but their tolerances and exposures to these stressors remain poorly documented. We evaluated habitat restrictions for two brittle star species from Caribbean coral reefs by integrating field observations, laboratory experiments and an ecophysiological model. The absence of one species from the warmest reefs results from vital activity restrictions during episodic low oxygen extremes, even though average conditions are well within physiological tolerance limits. Over the past decade, warmer temperatures have been significantly correlated with a greater frequency and intensity of hypoxic events. Continued warming will progressively exclude hypoxia-tolerant species, even if average oxygen remains constant. A warming-driven increase in frequency or intensity of low oxygen extremes could similarly accelerate habitat loss across other marine ecosystems.

Beyond the Trees:A Comparison of Nonwoody Species, and Their Ecology, in Papua New Guinea Elevational Gradient Forest

This study appraises the richness of nonwoody species (ferns, herbs, lianas, palms, and shrubs) in 31 sites across undisturbed and disturbed forests in the lowland of Papua New Guinea (PNG) and at montane forest sites at 2,700 m a.s.l. The assessment was conducted following the PNG National Forest Inventory protocol. The results indicate that with 463 nonwoody species, the tropical forest of PNG has remarkable species richness. No significant difference was observed in richness among lowland, logged and pristine, and montane forests. The study shows that the richness of nonwoody species increases with elevation, but this trend is different when considering the taxonomic group separately. Palms and lianas decrease along the elevation, whereas ferns, herbs, and shrubs are positively correlated with elevation. The species composition between lowland forest and mountain sites is different, with a tree fern and an Araliaceae as an indicator of the mountain forest. The findings demonstrate a high taxonomic richness of nonwoody species in PNG, supporting previous research but highlighting the significant contribution of nonwoody species to the overall plant richness in a tropical habitat.

Tropical savanna small mammals respond to loss of cover following disturbance: A global review of field studies

Small-mammal faunas of tropical savannas consist of endemic assemblages of murid rodents, small marsupials, and insectivores on four continents. Small mammals in tropical savannas are understudied compared to other tropical habitats and other taxonomic groups (e.g., Afrotropical megafauna or Neotropical rainforest mammals). Their importance as prey, ecosystem engineers, disease reservoirs, and declining members of endemic biodiversity in tropical savannas compels us to understand the factors that regulate their abundance and diversity. We reviewed field studies published in the last 35 years that examined, mostly experimentally, the effects of varying three primary endogenous disturbances in tropical savanna ecosystems—fire, large mammalian herbivory (LMH), and drought—on abundance and diversity of non-volant small mammals. These disturbances are most likely to affect habitat structure (cover or concealment), food availability, or both, for ground-dwelling small mammalian herbivores, omnivores, and insectivores. Of 63 studies (included in 55 published papers) meeting these criteria from the Afrotropics, Neotropics, and northern Australia (none was found from southern Asia), 29 studies concluded that small mammals responded (mostly negatively) to a loss of cover (mostly from LMH and fire); four found evidence of increased predation on small mammals in lower-cover treatments (e.g., grazed or burned). Eighteen studies concluded a combination of food- and cover-limitation explained small-mammal responses to endogenous disturbances. Only two studies concluded small-mammal declines in response to habitat-altering disturbance were caused by food limitation and not related to cover reduction. Evidence to date indicates that abundance and richness of small savanna mammals, in general (with important exceptions), is enhanced by vegetative cover (especially tall grass, but sometimes shrub cover) as refugia for these prey species amid a “landscape of fear,” particularly for diurnal, non-cursorial, and non-fossorial species. These species have been called “decreasers” in response to cover reduction, whereas a minority of small-mammal species have been shown to be “increasers” or disturbance-tolerant. Complex relationships between endogenous disturbances and small-mammal food resources are important secondary factors, but only six studies manipulated or measured food resources simultaneous to habitat manipulations. While more such studies are needed, designing effective ones for cryptic consumer communities of omnivorous dietary opportunists is a significant challenge.

Going with the flow: The case of three tropical reef fish transported to cool temperate waters following an extreme marine heatwave

The extreme marine heatwave of 2010/11 off Western Australia, and the anomalously high water temperatures in 2011/12 and 2012/13 were attributable, in part, to the out-of-season, pole-ward flowing Leeuwin Current (LC). While this event devastated some regional fisheries, it led to increased recruitment and/or large range extensions of tropical marine taxa in more southern, temperate waters. Three large-bodied tropical reef fishes, Lutjanus malabaricus, Pinjalo pinjalo and Lethrinus nebulosus, were caught in temperate waters off southern Western Australia, ∼1000–1500 km from their typical tropical habitats. Estimated ages of 8 to 9 years indicate they were spawned in the 2011/2012 or 2012/2013 austral spring/summer spawning periods. Swimming speed of late-stage larvae combined with the LC speed would have facilitated long-distance dispersal of larvae to temperate waters, where elevated water temperatures throughout the year, but particularly warmer winter months during their first 1–2 years of life, would have enabled these vagrant species to acclimatise to temperate waters.