Deterministic and stochastic processes are of great importance in influencing the composition of communities. Here, we tested if deterministic and stochastic processes have the same force of influence on functional traits of tiger moth communities. Specifically, we hypothesised that the functional traits of the tribe Arctiini would be more strongly influenced by stochastic processes (associated with spatial variables), given that these moths are primarily diet and habitat generalists within a highly diverse clade. They also exhibit high morphological trait dissimilarity and are capable of occupying a wide range of vegetation habitats. On the other hand, we hypothesised that the functional traits of the tribe Lithosiini would be more influenced by deterministic processes (associated with environmental variables), given that these moths are primarily diet and habitat specialist moths and tend to occur in more specific vegetation types. In agreement with our hypotheses, the functional traits of Arctiini species were better explained by variables related to stochasticity, while the functional traits of Lithosiini were explained by deterministic processes only. Thus, the processes shaping moth distributions across communities may vary according to species’ functional traits and interspecific relationships.

Tropical urban estuaries are understudied, where ecosystem health is often considered through a temperate lens. Here, we use stable isotopes and other biogeochemical parameters to begin to address the hypothesis that the biogeochemical drivers of water column chemistry in tropical urban estuaries are qualitatively different from those in temperate systems. We measured salinity, dissolved oxygen, temperature, turbidity, dissolved nutrients, enterococcus concentrations, and suspended particulate stable isotope and nitrogen (N) and carbon concentrations every two weeks for three years in the San Juan Bay Estuary, Puerto Rico. Enterococcus concentrations exceeded acceptable limits (35 CFU 100 ml-1) in all but three water samples measured in a densely populated channel within the estuary that receives urban runoff and untreated sewage (n = 207). The δ15N values were lowest in this channel, highest in the portion of the estuary with open exchange with the sea, and negatively correlated with dissolved inorganic nitrogen concentrations. This observation, is contrary to current paradigms that were developed in temperate estuaries. The source of the low δ15N values is unknown, but consistent with observations in the sediment and consistent with high rates of N fixation. In addition to the need for a basic understanding of the biogeochemical and ecological processes involved, these data serve as a baseline to compare the effects of restoration efforts and climate change.

Dry ecosystems are critical to the global carbon cycle. Seasonally dry tropical ecosystems as a whole are botanically megadiverse, yet we have little understanding of how diversity impacts aboveground carbon, which is particularly noticeable for insular Asia. Across 133 vegetation plots on the seasonally dry tropical island of Flores, we used spatially explicit models to determine how land use impacts aboveground carbon stocks and whether this is dependent upon multidimensional diversity. Carbon is greatest in primary forests and least in agricultural landscapes. However, we find that land use interacts with phylogenetic and species diversity to shape carbon stocks. Across almost all models, quadratic effects of diversity were better predictors of carbon, indicating that whilst the initial build-up of diversity increases carbon, greater diversity causes carbon decline. Results suggest that future conservation plans will be needed to balance carbon storage with multidimensional diversity, which may offer distinct benefits for ecosystem resilience and services.

Reservoir construction causes marked changes in hydrological, physical and chemical conditions, with rapid effects on aquatic communities. The initial filling phase, characterised by abrupt changes over days to weeks and the onset of vertical stratification, is particularly critical, yet its effects on planktonic ciliate communities remain poorly understood. Here, we combined high-frequency sampling with a two-strata design (surface and bottom) to investigate how the initial filling, and consequent vertical stratification, of a tropical reservoir affect the density, biomass and taxonomic groups composition of the planktonic ciliates community. We observed pronounced temporal and spatial changes, with physicochemical differences between strata and filling phases. We observed that the ciliate community responded to these changes with consistently higher density and biomass at the surface and in the middle of the filling period. Linear mixed-effects and generalised additive models supported our findings, with significant temporal variation in all attributes, with trajectories over the filling period characterised by an initial increase followed by a decline, and by marked shifts among ciliate groups that indicate a clear successional pattern. Our results suggest that the surface strata of the reservoir work as a dynamic and productive environment, whereas the bottom strata remain limiting for ciliate development, mainly due to lower oxygen concentrations. By providing one of the few high-resolution assessments of planktonic ciliates during reservoir filling, integrating vertical structure, temporal dynamics and taxonomic succession, this study extends the trophic-surge perspective to microbial consumers and highlights the value of ciliates as bioindicators during dam construction and early reservoir operation.