Fecal steroids as a potential tool for conservation paleobiology in East Africa

Conservation paleobiology seeks to leverage proxy reconstructions of ecological communities and environmental conditions to predict future changes and inform management decisions. Populations of East African megafauna likely changed during the Holocene in response to trends and events in the regional hydroclimate, but reconstructing these populations requires development of new proxies. We examine if fecal steroids are a viable proxy for megafauna populations since they are well preserved in sedimentary archives. We measured eleven fecal steroids in 87 fresh dung samples representing 22 species of megafauna in the Maasai Mara National Reserve (Kenya) and a further seven samples from captive animals. Using this reference library, four distinctive groups are identified, which reflect diet and biochemical modification of these inputs during digestion by the gut microbiome. Carnivore dung is characterized by more than ~ 75% cholesterol and primate dung includes uniquely high proportions of coprostanol. Two groups of herbivore are distinguished by their differing proportions of phytosterols that are consumed by eating plants and 5β-stanols produced during digestion. Under cross validation a random forests statistical model accurately classified 72% of dung samples to the species level using fecal steroids. Variability among individuals and between wild and captive animals suggests that fecal steroids in herbivore dung may reflect diversity and variability in diet, while a lack of variability in carnivore dung indicates that they cannot be identified to the species level in most instances. Our results suggest that fecal steroids may have utility in reconstructing the time-evolving composition megafauna populations in East Africa

Potential ecological and socio-economic effects of a novel megaherbivore introduction: the hippopotamus in Colombia

Introduced species can have strong ecological, social and economic effects on their non-native environment. Introductions of megafaunal species are rare and may contribute to rewilding efforts, but they may also have pronounced socio-ecological effects because of their scale of influence. A recent introduction of the hippopotamus Hippopotamus amphibius into Colombia is a novel introduction of a megaherbivore onto a new continent, and raises questions about the future dynamics of the socio-ecological system into which it has been introduced. Here we synthesize current knowledge about the Colombian hippopotamus population, review the literature on the species to predict potential ecological and socio-economic effects of this introduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (7–11%) and, on the current trajectory, we predict there could be 400–800 individuals in Colombia by 2050. The hippopotamus is an ecosystem engineer that can have profound effects on terrestrial and aquatic environments and could therefore affect the native biodiversity of the Magdalena River basin. Hippopotamuses are also aggressive and may pose a threat to the many inhabitants of the region who rely upon the Magdalena River for their livelihoods, although the species could provide economic benefits through tourism. Further research is needed to quantify the current and future size and distribution of this hippopotamus population and to predict the likely ecological, social and economic effects. This knowledge must be balanced with consideration of social and cultural concerns to develop appropriate management strategies for this novel introduction

Potential ecological and socio-economic effects of a novel megaherbivore introduction: The hippopotamus in Colombia

Introduced species can have strong ecological, social and economic effects on their non-native environment. Introductions of megafaunal species are rare and may contribute to rewilding efforts, but they may also have pronounced socio-ecological effects because of their scale of influence. A recent introduction of the hippopotamus Hippopotamus amphibius into Colombia is a novel introduction of a megaherbivore onto a new continent, and raises questions about the future dynamics of the socio-ecological system into which it has been introduced. Here we synthesize current knowledge about the Colombian hippopotamus population, review the literature on the species to predict potential ecological and socio-economic effects of this introduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (7-11%) and, on the current trajectory, we predict there could be 400-800 individuals in Colombia by 2050. The hippopotamus is an ecosystem engineer that can have profound effects on terrestrial and aquatic environments and could therefore affect the native biodiversity of the Magdalena River basin. Hippopotamuses are also aggressive and may pose a threat to the many inhabitants of the region who rely upon the Magdalena River for their livelihoods, although the species could provide economic benefits through tourism. Further research is needed to quantify the current and future size and distribution of this hippopotamus population and to predict the likely ecological, social and economic effects. This knowledge must be balanced with consideration of social and cultural concerns to develop appropriate management strategies for this novel introduction

Ontogenetic niche shifts in the American alligator establishes functional connectivity between aquatic systems

a b s t r a c t Individual animals undergoing ontogenetic shifts in habitat use may establish a mobile link between discrete ecosystems via movement of energy, nutrients and matter, as well as through impacts on ecosystem and habitat structure. The American Alligator (Alligator mississippiensis) is a model species for studying ecological implications of ontogenetic niche shifts, because they grow in size by several orders of magnitude, and they play a critical role as both top predators and ecosystem engineers. We used equal trapping effort, radio telemetry and nest surveys to document ontogenetic habitat shifts of alligators between hydrologically isolated, seasonal wetlands and riverine systems. To estimate the degree of functional connectivity between systems, we quantified alligator biomass and nutrient excretion in both systems. Seasonal wetlands provided nesting and nursery sites for adult females and juveniles, which constituted 0.78 g/m 2 biomass and excreted 0.05 g/m 2 /yr N, P, Ca, Mg, Na and K in that system. In contrast, the riverine system provided non-nesting habitat for adults and sub-adults of both sexes, totaling 0.18 g/m 2 biomass and excreting 0.01 g/m 2 /yr of nutrients. Furthermore, sub-adults and adult females were documented moving across the terrestrial matrix, while adult males spent the duration of the study in the creek. Our results demonstrated that ontogenetic niche shifts in alligators establish connectivity between seasonal wetlands and riverine systems and with the surrounding terrestrial matrix. These findings have implications for the definition of jurisdictional wetlands under the US Supreme Court's 2001 SWANCC decision and highlight the importance of ecological, as well as hydrological, connectivity

Subalusky_2018_mara_nutrient_dissolution_chambers

This file contains data on nutrient dissolution of hippo feces and wildebeest tissue measured using 5L chamber experiments filled with river water

Subalusky_2018_mara_river_biofilm_alldata

This file contains data on the biofilm growth and production on individual ceramic tiles placed in the Mara River at our three primary study sites for 3-4 weeks at a time; these are the individual values for 4-5 tiles at each site at each sampling period. The mean values for each site and visit were used for analysis

Subalusky_2018_mara_river_nutrients_tenpttransect

This file contains data on carbon and nutrient concentrations measured along a 10 point sampling transect down the Mara River, and the mean and standard error of all C and nutrient measurements over the period of study at our three primary study sites

Subalusky_2018_mara_river_physicochem_nutrient_data

This file contains data on discharge and water column parameters measured monthly at our three primary study sites in the Mara River from Jun-Aug 2011, Jul-Dec 2012, and Aug 2013-Mar 2014

Subalusky_2018_mara_nutrient_limitation_assays

This file contains data on biofilm growth on nutrient-diffusing substrates, comprised of glass discs (for measurements of cholorophyll a) and cellulose sponges (for measurements of respiration) on cups of agar amended with different nutrients

Subalusky_2018_mara_experimental_stream_tiles

This file contains data on the biofilm growth and production of indvidual ceramic tiles placed in experimental streams and destructively sampled weekly to measure biofilm growth over time