Tag: Richard Emlet

Water Flux in a Mangrove Forest

Presenter: Katalin Plummer

Co-Presenters: Alyssa Bjorkquist

Faculty Mentor: Richard Emlet, Jan Hodder

Presentation Type: Poster 48

Primary Research Area: Science

Major: Marine Biology, Spanish

Water flux plays an important role in structuring and maintaining biodiversity in aquatic environments, such as tropical mangrove forests where lower water flux could reduce organic carbon outflow so that critical nutrients are more available for regulating organismal trophic processes. In the present study, we used two dissolution methods to estimate water flux at two mangrove sites within Bocas del Toro, Panama. We investigated how water flux differs with respect to mobility of a substratum (mobile versus stationary) as well as its position within a mangrove forest (exterior versus interior). We also examined organic carbon content of the sediment of each site in relation to water flux activity to ascertain the existence of a correlation between water flux and nutrient cycling in these environments.

Water flux differed significantly between sites for both the long-term and short-term (p < 0.001, both) dissolution trials. Additionally, we found a significant difference in sediment carbon content between sites (p < 0.01). While the two sites differed significantly from one another overall, these results do not suggest that water flux alone significantly affects marine community composition within a mangrove forest. We speculate that outside abiotic or geographic factors also influence physical conditions of these communities. Studying the intersection of biological and physical factors within mangrove forests may inform future research and conservation efforts pertaining to these environmentally sensitive habitats.

Radiole Regeneration of the Feather Duster Worm, Schizobranchia insignis

Presenter: Shannon Brown

Faculty Mentor: Richard Emlet, Kelly Sutherland

Presentation Type: Poster 49

Primary Research Area: Science

Major: Marine Biology

The annelid feather duster worm, Schizobranchia insignis, is a prevalent marine invertebrate found along the coastlines of the Northeastern Pacific Ocean. The regenerative ability of feather duster worms is frequently studied as a model for regeneration because the annelid phylum demonstrates a pronounced array of regeneration processes. The main purpose of my study is to examine the regeneration of a single radiole in S. insignis. Previous studies have examined the regeneration of the entire posterior and anterior region of the worm; however, limited information is available on radioles, the anterior appendages used for feeding and respiration. By cutting S. insignis radioles and observing resulting regeneration, I was able to categorize the regeneration into 12 distinctive stages with detailed descriptions of the external and internal structures that developed during each stage. In addition, to support potential regenerative conclusions, I performed an overall survey of the feather duster worm’s branchial crown and found that there is a non-significant positive linear relationship between the number of radioles and the weight of the S. insignis. Although a full analysis of the data has not been completed, I expect that the information collected for this study will provide additional knowledge to the currently limited regeneration field.

Sea Star Plasticity: Morphological Variation of Pisaster ochraceus in Response to Wave Exposure

Presenter: Alyssa Bjorkquist

Faculty Mentor: Richard Emlet, Kelly Sutherland

Presentation Type: Poster 47

Primary Research Area: Science

Major: Marine Biology, Psychology

Funding Source: Undergraduate Research Opportunity Mini-Grant, UROP, $1000

Pisaster ochraceus (the Ochre Sea Star) is a keystone species in the NE Pacific whose role as an ecological engineer influences intertidal diversity by predating on space-competing organisms. Individuals inhabit a broad range of habitats ranging from sheltered coves to exposed cliffs and experience large temporal and spatial variability in water flow throughout their lifetime. However, it is largely unknown how sea star body shape changes between wave- exposed and wave-sheltered environments throughout an organism’s lifetime. Wave exposure was measured at each study site near Charleston, OR using dissimilar metal dissolution and intertidal zonation of sessile organisms. Furthermore, I analyzed how aspects of juvenile and adult P. ochraceus morphology differed between sites as functions of wave exposure.

Sites with more wave exposure were associated with greater anode mass loss over time (F1,30 = 256.21, p < 0.001) and broader vertical zone boundaries relative to mean water level than sheltered sites (F2,8 = 3.03, p < 0.01). Adult sea star populations from wave-exposed sites had longer, narrower arms and smaller central discs relative to individuals from sheltered habitats for a given weight (F2,152 = 70.0, p < 0.001). Juveniles appeared to exhibit similar morphological trends but results were inconclusive. The relationship between wave exposure and sea star morphology indicate that hydrodynamic conditions play a large role in shaping sea star development and environmental adaptability post-larval metamorphosis.

Abundance & Composition of Sponges, Algae, and Oysters on Mangrove Prop Roots: Effects of Location in Bocas Del Toro, Panama

Presenter(s): Ellie Jones − Marine Biology

Co Presenter(s): Emily Bork

Faculty Mentor(s): Richard Emlet

Poster 78

Research Area: Marine Biology

Funding: Global Education Oregon Mills Scholarship

Mangrove forests create an important community at the interface of land and sea. Since 1980, 20-35% of global mangrove area has been lost due to deforestation, aquaculture, and pollution. Degradation or loss also impacts the marine communities living on the prop roots. In this research, we studied mangrove communities near the Bocas Research Station of the Smithsonian Tropical Research Institute (BRS-STRI) in Panama to determine if the abundance and composition of prop root epibionts vary with proximity to human development. We hypothesized that sponge, algal, and oyster abundance will increase with proximity to human development due to higher nutrient content, but sponge species richness will decrease due to conditions that can only be tolerated by one or a few dominant species. We took water quality and biological measurements from a village site, adjacent to a human-occupied shoreline, and a reserve site, in the vicinity of BRS-STRI. Water quality measurements included temperature, salinity, pH, water clarity, and organic matter. Biological measurements included sponge, algae, and oyster abundance, as well as sponge color and morphotype. There were a greater number of sponge species at the reserve than the village site. Temperature was higher at the reserve site, but no other abiotic factors differed. Turf algae was more abundant at the village site, but no other epibionts differed. Our work is significant because mangrove communities are particularly vulnerable to environmental stressors. It is important to identify potential bioindicators of environmental stress in these ecosystems to be able to adequately monitor further change.

Ontogenetic Shifts in Resource Use And Behavior in the Striped Parrotfish, Scarus Iseri, on a Patch Reef in Bocas Del Toro, Panama

Presenter(s): Haley Faringer − Environmental Science

Co Presenter(s): Rulon Hardy, Christina Ellison

Faculty Mentor(s): Richard Emlet, Jan Hodder

Poster 60

Research Area: Natural/Physical Science, Marine Biology, Ecology

Scarus iseri, the striped parrotfish, is among the most abundant parrotfish on Caribbean coral reefs. As grazing herbivores, they shape community structure by transmitting primary production up the food chain, regulating algal biomass, and facilitating benthic settlers in the process of removing patches of algae. S. iseri are protogynous hermaphrodites with 3 life stages (juvenile, initial and terminal) identifiable in the field. Our study investigates differences in range size, habitat utilization, and behavior between the juvenile and terminal phases. Through this research, we hoped to gain a better understanding of how these fish utilize their habitat as they grow, and how resources are partitioned among members of a population.

Our research was conducted at House Reef, near the Smithsonian’s Tropical Research Institute in Bocas del Toro, Panama. We followed 6 focal individuals of each life stage for a 15-minute period to establish their range. These parameters were chosen due to time constraints of the study period. We only had 4 days to complete the research, including data analysis, and wanted to maximize both the amount of time we followed each fish, and the number of replicates for each life stage. The numbers we chose reflect a compromise between these two variables. Using survey flags and transect-tape, we calculated the area of each range and drew a map of its shape.

Before conducting surveys in the field, we constructed an ethogram, or a table of observed behaviors for the fish. Then for 5 minutes of the 15-minute period we observed and recorded behaviors of the fish according to our ethogram. This allowed us to gain insight about feeding frequency, substrate used for feeding (e.g. sediment, sponge, sand, etc.), the proportion of each type of substrate used, and social behavior within a population.

Our results suggest that range size increases with more advanced life stage. Time allocations for feeding and non-feeding behaviors are similar between the two stages and both life stages utilize the same substrate types for feeding, in similar proportions. Juveniles frequently form groups, while terminal phase individuals are often found alone.

Because Scarus iseri is so prominent in the Caribbean Ocean, it has an increased ability to transfer nutrients through trophic levels. Not only is it important to understand how resource utilization within this species is affected by life stage, but how this resource utilization affects nutrient levels and habitat availability for other species on reefs of the Caribbean Ocean. With the recognition of variable social behaviors and range sizes between juveniles and terminal adults, we hope to better understand the nature of these fish’s relationship with each other and other stakeholders on the reef. The data collected is important because it can be used to inform the management of marine protected areas aimed at preserving this important group of fish.

Do Chiton Larvae Have Kidney Stones? Unidentified Crystal Structures in the Larval Development Of Mopalia Hindsii

Presenter(s): Christina Ellison − Marine Biology

Faculty Mentor(s): Richard Emlet

Poster 59

Research Area: Natural Science

Funding: National Science Fund (REU program)

Chitons are marine molluscs in the class Polyplacophora. Like many marine organisms, chitons have a pelagic, dispersive larval stage which settles and metamorphoses into an adult form that lives on the benthos. During development, chitons must acquire structures that enable them to function in each of these environmental contexts. While many features of development have been well documented, one structure has yet to be reported. Chiton larvae consistently form a pair of birefringent, crystalline structures, best viewed with cross-polarized light. What they are made of and their function in the animal are unknown. The location and timing of these structures appear consistent with the “larval kidneys” as described by Baeumler et. al 2011, so we hypothesized they could be involved in kidney function. The purpose of this study was to establish a developmental timeline for these structures, to determine their chemical composition, and to record morphological data concerning their appearance (size, shape, number, location). This was achieved by raising chiton larvae and monitoring their development through microscopy. Calcein-tagging, fluorescence microscopy, and a murexide test were used to infer chemical composition. Our results suggest the structures form 4 days post-fertilization and persist at least 5 days after metamorphosis. The structures are composed of many small, calcium-containing crystals. They have been observed in 7 species across 2 suborders and may be a universal feature of chiton development. Our findings are consistent with possible kidney involvement, but functional studies must be done to further support this idea.