Population dynamics of the threatened staghorn coral, Acropora cervicornis, and the development of a species-specific monitoring protocol

Historically, Acropora cervicornis was found in high densities on many Caribbean, Florida, and Gulf of Mexico reefs. A disease outbreak in the late 1970s and 80s caused up to 99% loss of A. cervicornis cover at some sites, leaving populations sparsely distributed throughout its range and typically found as isolated colonies. Even though populations are depauperate causing a decrease in sexual reproduction, its fast growth rate and ability to reproduce through asexual fragmentation affords this species the potential for quick recovery and population growth. However, limited to no natural recovery has been documented. Many of these populations are poorly studied because most monitoring programs are not designed to capture A. cervicornis’ unique life history characteristics. Its patchy distribution, complex growth form, frequent fragmentation, and dislodgment present a challenge for long term tracking. Furthermore, its ability to exist from small isolated colonies to semi-continuous patches spanning hectares makes defining individuals to assess abundance, survival, health, and growth a difficult task. The aim of this dissertation was to develop a species-specific monitoring protocol to describe the abundance and cover of A. cervicornis and the effects of disease, predation, and disturbance events across space and time. The monitoring protocol was developed and used across three sub-regions of the Florida Reef Tract (Broward County, Middle Keys, and Dry Tortugas). Several permanent 3.5 m radial plots were installed across multiple sites in each sub-region. A species census, percent cover, and demographic data of a sub-set of colonies were collected three times per year (winter, summer, and fall) from 2008-2016. These results were then used to assist in designing and testing optimal outplant strategies. Outplanting occurred at seven sites in Broward County, FL between 2012- 2015. Experiments were designed to assess the effects outplant colony density, host genotype, colony size, and attachment technique had on colony survival, growth, and health. The monitoring protocol was successfully used for identifying spatial and temporal patterns and trends in cover, disease, and predation on A. cervicornis across a range of population sizes. Percent cover of living A. cervicornis declined significantly during the duration of the project. Disease prevalence and occurrence was highest during the summer. Colony size and volume increased with depth and were the largest in the Broward County sub-region. Disease caused the most mortality, however fireworms were the most prevalent cause of recent mortality. Disease and predation were more prevalent on masses (individuals larger than 1.5 m in diameter). The outplant experiments showed that colony survival and health were greatest when colonies had greater than 15 cm in total tissue and in densities less than 1 col/m2. Host genotype and outplant site had variable effects on survival and growth. Outplanted colonies quickly acclimated to their environment and increased colony abundance within sites by fragmentation. Prevalence of disease and predation were lower on outplanted colonies than wild colonies. Frequent disturbances such as tropical storms, hurricanes, and disease events caused increased, prolonged, and widespread mortality and fragmentation, however periods void of disturbances resulted in recovery and growth. Therefore, reducing the effects of climate change and determining and decreasing the causes of disease could promote species recovery. In the meantime, population enhancement by outplanting is a viable way to assist species conservation and recovery

Outplanting Technique, Host Genotype, and Site Affect the Initial Success of Outplanted Acropora cervicornis

Acropora cervicornis is the most widely used coral species for reef restoration in the greater Caribbean. However, outplanting methodologies (e.g., colony density, size, host genotype, and attachment technique) vary greatly, and to date have not been evaluated for optimality across multiple sites. Two experiments were completed during this study, the first evaluated the effects of attachment technique, colony size, and genotype by outplanting 405 A. cervicornis colonies, from ten genotypes, four size classes, and three attachment techniques (epoxy, nail and cable tie, or puck) across three sites. Colony survival, health condition, tissue productivity, and growth were assessed across one year for this experiment. The second experiment assessed the effect of colony density by outplanting colonies in plots of one, four, or 25 corals per 4 m2 across four separate sites. Plot survival and condition were evaluated across two years for this experiment in order to better capture the effect of increasing cover. Colonies attached with a nail and cable tie resulted in the highest survival regardless of colony size. Small corals had the lowest survival, but the greatest productivity. The majority of colony loss was attributed to missing colonies and was highest for pucks and small epoxied colonies. Disease and predation were observed at all sites, but did not affect all genotypes, however due to the overall low prevalence of either condition there were no significant differences found in any comparison. Low density plots had significantly higher survival and significantly lower prevalence of disease, predation, and missing colonies than high density plots. These results indicate that to increase initial outplant success, colonies of many genotypes should be outplanted to multiple sites using a nail and cable tie, in low densities, and with colonies over 15 cm total linear extension

Assessing the host status of banana and other plant species to the enset root mealybug Paraputo ensete (Williams & Matile-Ferrero) (Hem.: Pseudococcidae) in Ethiopia.

Ninety backyard gardens in the south-eastern Ethiopian highlands with enset (Ensete ventricosum (Welw.) Cheesman), banana and various annual crops were assessed for the presence of enset root mealybugs (Paraputo ensete (Williams & Matile-Ferrero)). This study presents the first observation of enset root mealybugs on banana. This pest has until now been exclusively recorded on enset in Ethiopia. In the Dilla Zuria district of the Gedeo zone, southern Ethiopia, infested banana mats of the ‘Pisang Awak’ (ABB genome) landrace were observed adjacent to infested enset plants in three small-holder backyard gardens. As roots of banana mats and enset plants were overlapping and intertwined, and large numbers of mealybugs were observed on enset roots, possibly representing an overpopulation, the observed mealybugs on banana might have represented a “chance infestation". The smaller size of mealybugs on banana roots might indicate a non-optimal host status of this crop. Experimental choice and no-choice pot trials however provided another indication of the possible host potential of ‘Pisang Awak’ and of an additional banana cultivar ‘Matooke’ (AAA-East African Highland). The enset root mealybug was able to fully develop, produce viable offspring and survive on both banana cultivars. Not all investigated banana cultivars presented this host status, and the susceptibility of most Musa cultivars remains low

First report of the enset root mealybug Paraputo ensete (Williams & Matile Ferrero) (Hem.: Pseudococcidae) on banana in Ethiopia.

Enset root mealybugs, a major pest affecting the cultivation of the enset crop in the Ethiopian highlands, have for the first time been observed on banana mats indicating the potential host status of Musa spp. These observations were made under natural conditions in backyard gardens in the Gedeo zone, southern Ethiopia, on the root system of banana mats of the ‘Pisang Awak’ (local name ‘Feranji Muz’, ABB genome group) landrace. Here, we confirm the identification of the collected enset root mealybug specimens on banana mat root systems as Paraputo ensete (Williams & Matile-Ferrero) (Hemiptera: Pseudococcidae) through DNA analysis

Vertebrate Photography: 3rd Place

https://nsuworks.nova.edu/occ_shuttershark_2008/1003/thumbnail.jp

Data from: Invasive Bromus tectorum alters natural selection in arid systems

While much research has documented the impact of invaders on native communities and ecosystem services, there has been less work quantifying how invasion affects the genetic composition of native populations. That is, when invaders dominate a community, can they shift selection regimes and impact the evolutionary trajectory of native populations? The invasion of the annual grass Bromus tectorum in the Intermountain West provides an opportunity to quantify the effects of invasion on natural selection in wild populations. The shift from a perennial-dominated native community to one dominated by a highly competitive annual species alters the timing and intensity of competitive pressure, which has the potential to strongly shift selection regimes for native plants. To quantify traits under selection in contrasting environments, we planted seeds of two native perennial grasses, Elymus multisetus and Poa secunda, into three invaded, invaded but weeded and relatively uninvaded sagebrush systems. We quantified phenotypic traits of seedlings from separate maternal plants, describing differences in phenotypes among individuals. We then asked which traits were associated with survival and plant size in adjacent invaded and uninvaded sagebrush systems, following individual seed performance for 3 years. We found evidence for divergent selection between invaded and uninvaded sagebrush systems, with contrasting phenotypic traits associated with greater survival or plant size in these different growing conditions at all three field sites. For example, at one field site, P. secunda families with higher root tip production were more likely to survive in invaded and weeded environments, but this was not the case in uninvaded environments. Similarly, for E. multisetus, root mass fraction, seed mass and allocation to coarse or fine roots affected survival and plant size, again with contrasting relationships across invaded, weeded or uninvaded environments. Synthesis. Impacts of invasive species extend beyond ecosystem and community composition changes and can affect the evolutionary trajectory of native populations. By quantifying natural selection in invaded landscapes, we identified phenotypic traits that are potentially adaptive in these invaded systems. Importantly, these traits differed from traits associated with success in uninvaded communities. This insight into adaptive, contemporary evolution in native species can guide restoration and conservation efforts

Coral reef restoration and staghorn coral conservation: lessons learned over 10 years of research

Acropora cervicornis restoration and conservation has grown in importance over the past few decades, especially following its listing as threatened under the US Endangered Species Act in 2006. This listing prompted initiation of restoration projects across the Florida Reef Tract and Greater Caribbean. Since 2007, three A. cervicornis nurseries have been established at the northern most extant of the species range (Broward County, FL) raising over 7,100 colonies. Outplanting began in 2009 and by 2012, approximately 1,000 colonies were being outplanted from the nurseries each year to local reefs. Since establishment, our program has been focused on determining optimal nursery and outplant propagation methods to increase restoration efficiency and species recovery. Through development and expansion of our program numerous aspects of the restoration process have been studied. Nursery colony survival was affected by colony orientation, host genotype, site, time of year and growing platform. Growth was fastest during the summer, varied by colony orientation, host genotype, and site, but was similar across platforms. Disease and predation prevalence were lower in cooler months and on floating platforms. We have not seen long-term host genotype resistance to disease or predation. Active management (removal) of predators increased nursery colony health and reduced predation pressure. Tropical disturbances had devastating effects on our coral nursery reducing colony health through stress, disease, and fragmentation, but these effects were variable across nursery platforms and sites. Outplanted colonies quickly attached to the substrate, created habitat, and over years propagated across each outplant site. Host genotype, colony size, attachment method, colony spacing, and several temporal and spatial characteristics affected colony survival. Colony growth was also variable and influenced by host genotype and site, but not by attachment method. Host genotype did not have an effect on prevalence of disease and predation, but increased distance between outplanted colonies reduced both. This restoration program has had increasing success in raising and propagating thousands of A. cervicornis colonies with a small impact on the wild population, illustrating that by using the proper techniques, facilitation of species recovery through population enhancement is possible