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Agricultural and urban contaminants enter aquatic environments at concentrations that can affect a variety of sublethal endpoints, including organismal behavior, which can in turn lead to impacts at the population level. The San Francisco Bay Delta (SFBD) is home to multiple threatened aquatic species, such as Delta smelt (Hypomesus transpacificus) and Longfin smelt (Spirinchus thaleichthys), with contaminant exposure likely playing a role in widespread population declines. Pesticides induce hyperactive or hypoactive states in these species, though little is known of the extent of hyperactivity that could be elicited by exposure to neurotoxic compounds. My study used pentylenetetrazole (PTZ), a γ-aminobutyrate (GABA) receptor antagonist, to explore hyperactive behavior in Delta smelt and Longfin smelt. I evaluated induced and spontaneous movement in light and dark conditions following exposure to increasing concentrations of PTZ. Delta smelt and Longfin smelt exposed to PTZ experienced changes in behaviors reflective of induced hyperactivity, including distance moved and swimming velocity, as well as spontaneous hyperactivity, such as time and frequency spent freezing, bursting, or entering the center of the arena (anti-thigmotaxis). The maximum hyperactivity for Delta smelt larvae was recorded following exposure to 8mM PTZ and for Longfin smelt larvae to 4mM PTZ. Together, this information not only confirms that PTZ could be used as a positive control in future behavioral toxicology studies for hyperactivity, but also provides for a better understanding of hyperactive behavior in these species of ecological concern.

The wild abundance of Longfin smelt (Spirinchus thaleichthys, LFS) in the San Francisco Estuary (SFE) has declined to less than 1% of pre-1980’s numbers. As a result, they have been listed as “threatened” under the California Endangered Species Act since 2009. In an effort to avoid localized species extinction, a captive culture program was created for LFS through the Fish Conservation Culture Laboratory at the University of California, Davis. Larviculture methods for LFS are still being optimized to ensure a successful culture program. For my MS thesis, I tested the impacts of rearing temperature on early post-hatch LFS larvae from three different parental clutches to identify which rearing temperatures are best for successful development of these early life stages. I reared newly fertilized embryos and post-hatch, non-feeding yolk-sac larvae in freshwater (0 ppt) at 10, 12, or 15°C until 3 days post-hatch (dph). I measured larval morphometrics (total length, eye diameter, yolk sac area), and mortality for all groups. I was the first to evaluate the incidence and severity of jaw and spinal malformations for cultured LFS. Larvae reared at 15°C were smaller (mean ± SE; 0.52 ± 0.0040 mm), significantly younger at hatch (13.1 ± 0.1 days post-fertilization; dpf), and had slightly higher mortality and increased spinal malformations compared to other rearing temperatures. Embryos reared at 10 and 12°C were of similar size (10℃: 0.59 ± 0.0030 mm, 12℃: 0.56 ± 0.0030 mm), but 10°C larvae were significantly older at hatch (10℃: 18.4 ± 0.05 dpf, 12℃: 15.8 ± 0.1 dpf). Clutch had a much more variable impact on response metrics, markedly in size, suggesting that parentage may mediate developmental responses to unfavorable environmental conditions and change. No incidences of jaw malformation and a very small percentage of spinal malformations were observed amongst all treatment groups. Overall, the novel results described in this study suggest that parentage modifies the impacts of rearing temperature on larval development and survival. As a result, I make recommendations to broaden the impact of future LFS and other sensitive larval fish studies on conservation larviculture techniques. While our understanding of factors impeding LFS culture is limited, this study represents a significant step towards identifying more biologically efficient larviculture and conservation management techniques for this and other critically threatened fish species.

The benthic zone of lakes can be a hotspot for lake energy flows and nutrient cycling. Indeed, the notion of benthic “ooze” and its role in the recycling of nutrients forms a conceptual cornerstone of ecology (Lindeman 1942). Benthic habitats can vary from soft, muddy sediments rich in organic matter and nutrients to bare rock covered by thin biofilms. These habitats form the linkage between lake and watershed, and support a range of ecosystem processes—from exchange of groundwater nutrients, internal nutrient cycling, mineralization of organic matter, heterotrophic respiration, and benthic algal production—that each vary in importance between different waterbodies. Clear Lake, CA, and Lake Tahoe represent two systems that span a gradient in trophic level, depth, and underlying geology. The former is shallow, and extremely productive, while the latter is deep and has nutrient concentrations near detection limit. Both, however, are large lakes and are extremely important water resources in California. We set out to characterize two very different, but nevertheless important, benthic processes that are adversely affecting water quality in each lake.Benthic algae, or periphyton, blooms may be increasing in oligotrophic, clear water lakes globally in response to increases in water temperature and nutrient loads, often associated with climate change. In many regions, climate change is altering the duration of snow cover, the frequency and severity of drought, and storm intensity, all of which have the potential to affect periphyton growth rates. Lake Tahoe, located in the Sierra Nevada Mountains of California and Nevada, has anecdotal reports that the frequency and severity of nearshore periphyton blooms have increased in recent years. Such blooms decrease both water quality and the aesthetic value of nearshore areas. While recent studies have documented changes in periphyton biomass, it is difficult for in situ studies to disentangle the individual and interactive effects of temperature and nutrients on periphyton growth rates. Consequently, we used laboratory experiments to examine 1) seasonal variability in periphyton biomass and metabolism, 2) the role of temperature, nutrients, and their interactive effects on determining periphyton metabolic rates, and 3) seasonal variability of the aforementioned temperature and nutrient effects. By measuring changes in dissolved oxygen in sealed incubation chambers containing rocks collected from the nearshore, we quantified rates of gross primary production (GPP), ecosystem respiration (ER), and net ecosystem production (NEP). Our experiments had two nutrient treatments (ambient and augmented with nitrogen and phosphorus) and four temperature treatments (ambient, +3, +6, and +9 °C above ambient) to simulate warming during different seasons, and nutrient loading associated with increased runoff. We found that temperature drove the majority of variability in periphyton metabolic rates and increased GPP, ER, and NEP by 4-7% per 1°C of warming. The effect of warming varied seasonally with larger effects in colder months. Warming also stimulated ER more so than GPP, with decreasing trends of NEP with warming during summer months. Nutrient additions had variable effects on rates of GPP, ER and NEP, but increased ER rates by 6-7% at maximum nutrient concentrations observed in the field. However, in contrast to our expectations, we found little evidence for interactive effects between temperature and nutrients for GPP and NEP, and a small, negative, inhibitory interaction for ER. In all, these experiments provide evidence that warming can increase periphyton metabolic rates in oligotrophic systems even in the absence of increased nutrient loads in cases where periphyton are not nutrient limited. These effects on littoral zones of lakes will have important consequences for ecosystem structure and function, and management efforts to curb nutrients will be crucial for limiting periphyton blooms under climate change.Eutrophication continues to be a problem in aquatic systems globally, resulting from excessive nutrients such as phosphorus and nitrogen. Nutrient sources can be external (i.e. runoff) or from within the lake (internal loading). In the case of phosphorus, internal loading can occur several ways: 1) chemically reduced conditions at the sediment-water interface of lake bottoms (usually induced by anoxic conditions) facilitate the reductive dissolution of phosphorus from the sediments to the overlying water, 2) mineralization of organic matter, and 3) physical resuspension of shallow sediments, and 4) elevated pH (commonly the result of intensive algal productivity) that results in ion exchange in sediments. Efforts to restore Clear Lake, a hypereutrophic lake located in Lake County, CA, have largely focused on external nutrient inputs as the cause of excessive phosphorus concentrations. This study provided the first direct measure of internal phosphorus fluxes from the nutrient-rich lake-bottom sediments to the overlying water column using incubations of intact sediment cores. Similar to other studies, soluble reactive phosphorus (SRP) flux rates from sediments ranged from 8.8 to 26.7 mg SRP m-2 d-1 in anoxic treatments and from -4.2 to 0.9 mg SRP m-2 d-1 in oxygenated treatments. We found little seasonal variation in anoxic SRP flux rates between winter and summer incubations despite large temperature differences between these two seasons. We hypothesize that early summer drawdown of redox-sensitive sediment P pools can potentially limit sediment phosphorus flux rates later in the season despite the positive effects of warmer summer temperatures on SRP flux. Thus, characterizing phenology of sediment P pools is important for estimating annual internal phosphorus loads in lakes. Large internal fluxes of P in this system were largely ignored during establishment of nutrient TMDLs for the watershed. This study highlights the importance of measuring internal fluxes of P and its seasonality when setting nutrient TMDLs or designing restoration strategies for a watershed.

Marine species are under mounting threat from stressors associated with climate change, such as ocean acidification and warming. Extreme events such as marine heatwaves (MHWs) are also forecasted to increase in frequency, intensity, and duration. The environment varies greatly with regard to the factors associated with these climatic stressors. Parameters of the physical environment are heterogeneous spatially across gradients associated with marine macrophytes such as kelp forests, and variable across time associated with regular cycles such as seasons, and events such as upwelling or MHWs. Therefore, in this dissertation, I investigated whether this physicochemical variability associated with kelp forest ecosystems or MHWs can drive transgenerational effects in marine invertebrate larvae exposed to stressors associated with climate change (temperature and pH). Early life history stages are believed to be particularly vulnerable to the stressors associated with global change, therefore I focused my investigations on the early larval stages of two marine invertebrate species of ecological and commercial importance: the purple urchin, Strongylocentrotus purpuratus and the green-lipped mussel, Perna canaliculus. First, I monitored the conditions inside and outside a kelp forest environment in the Santa Barbara Channel (SBC) and investigated the maternal effects of conditioning S. purpuratus inside and outside the kelp forest for 6 months spanning gametogenesis. pH and temperature were slightly elevated and more predictably variable inside the kelp forest as compared to outside. After acclimation, the urchins were spawned and their larvae were raised under high and low pCO2 conditions in lab to assess their physiological response to the maternal and developmental environments. Larvae from outside conditioned mothers were more resilient to an additional stressor in the form of an acute thermal tolerance trial, and tended to have more skeletal development than those from inside conditioned mothers. Two experiments were also conducted to explore the paternal effects of simulated MHWs, on P. canaliculus aquaculture in the Marlborough Sound region of New Zealand, which has suffered devastating MHW events in recent years. In the first experiment, I exposed male P. canaliculus to an acute 1-week exposure to MHW or ambient temperatures and then raised their larvae under warm of ambient temperatures to the veliger stage. Paternal and developmental heat exposure had a negative impact on successful development of the larvae, but veliger larvae from heat exposed fathers had the highest thermal tolerance in a lethal tolerance assay. In the final experiment, I conditioned P. canaliculus males from wildtype lineages and lineages selectively bred for heat tolerance to a chronic 1-month exposure to a slightly lower MHW temperature in order to investigate the interaction between selective breeding and paternal effects. Elevated paternal and larval temperatures had negative impacts on successful larval development and size for larvae from both selectively bred and wildtype lineages. Overall, the results of this dissertation indicate that heterogeneity in abiotic factors can have transgenerational effects through the maternal and paternal line with consequences for how key marine invertebrates respond to stressors associated with global change. It will be critical to consider the impact of natural gradients on plasticity and how transgenerational effects can be used to inform aquaculture practices to mitigate the effects of MHWs.

El Niño conditions are known to alter ocean circulation patterns causing a reduction in upwelling events that leads to warmer water with reduced concentrations of inorganic nutrients in coastal waters. The 2015/16 El Niño event resulted in significant losses of the habitat forming giant kelp, Macrocystis pyrifera, with concurrent increases in the non-native, invasive brown alga Sargassum horneri across San Diego, CA. M. pyrifera is known to be highly sensitive to both temperature and nutrient availability, however much less is known about the response of S. horneri to these conditions. The goals of this study were to investigate if and how El Niño-like conditions may have facilitated the invasion of S. horneri in southern CA using both laboratory and field-based approaches. In laboratory experiments, S. horneri maintained positive growth in conditions well exceeding M. pyrifera’s thermal tolerance limits. Temperature was the main driver of growth rates for S. horneri juveniles, but nitrate concentration affected other measurements of algal physiological performance, such as photosynthetic efficiency/maximum quantum yield and pigment concentration. Further, in the field, S. horneri displayed strong seasonality, but with contrasting timing to native M. pyrifera suggesting that the phenology of these two species may be offset. Given the rise in sea surface temperatures and predicted increases in the frequency and intensity of El Niño and marine heat waves, these findings suggest there is increased risk of further invasion by the non-native S. horneri within southern California’s iconic giant kelp forests, but more research is needed to evaluate future trends.

Passive acoustic monitoring (PAM) is commonly used to study behavior and population dynamics of soniferous fish species in a cost-effective, minimally invasive manner. However, understanding the strengths and limitations of PAM for this purpose requires an assessment of variability in CAS of target species as a function of time, space, and proximity of spawning fishes. In this study we evaluate temporal and spatial trends in CAS by Nassau Groupers (Epinephelus striatus) using an array of six hydrophones deployed at a large Nassau Grouper FSA on Little Cayman, Cayman Islands. We collected continuous data for nine days during the winter spawning season, and subsequently employed an automatic classifier to extract the embedded Nassau Grouper CAS. Using these data, we qualitatively and quantitatively analyzed variability in temporal trends across the spatial array with a Bayesian mixed effects model. We found a clear degradation in accuracy of temporal calling patterns at the FSA as distance from the spawning site increased beyond 200 meters, and observed higher correlations among the most proximal hydrophone pairs than the most separated pairs. Our model predicted strong effects of fish proximity, spawning behavior, and crepuscular periods on detected calling rates of Nassau Grouper that corroborate with and add to the present literature. Our findings suggest a high degree of variability within relatively short distances from a sonic target, thus imploring a need for spatial resolution in acoustic analyses.

The California mussel (Mytilus californianus) is an ecologically and culturally important bivalve mollusc species that provides a habitat for hundreds of other taxa throughout rocky intertidal environments along the Pacific Coast of North America. Mytilus californianus is a well-studied organism in the fields of coastal archaeology and marine ecology, but an improved understanding of its shell structure, life-history traits, and calcification patterns could provide valuable insights paleo-seasonality or paleoceanography of Holocene coastal environments. Here, I investigated shell characteristics of M. californianus across a variety of spatial and temporal scales in order to assess and optimize its utility as a biogenic archive. By applying morphometrics, optical microscopy, and geochemical data-synthesis methods to modern, historic, and Holocene M. californianus shells collected throughout the California Current System, I established relationships between growth banding and seasonality, documented the influence of micro- habitat on shell growth, characterized stable isotopic variability over seasonal, ontogenetic, and millennial scales, and identified regional differences in calcification patterns. I present evidence for rapidly shifting calcification patterns in northern California mussels from the early 2000s to 2020, including thinner inner calcite layers and lowered contrast between dark-light growth bands. Shifting shell characteristics were correlated with greater temperature extremes, heightened temperature variability, and more intense upwelling in the past few years relative to the early 2000s. Northern populations of M. californianus preferentially grow their shells during stable, moderate periods (mean monthly temperature near 13°C) with low variability (< 5 C° seasonal temperature range), as indicated by calcite-rich light bands. I then expanded the geographic and temporal scope to characterize geochemical variability of M. californianus shells throughout southern California over millennial scales. By synthesizing the ample published stable isotope records from archaeological mussel shells of the Channel Islands, California, I found that individual analysis of complete stable isotope profiles of many shells offers more valuable paleobiological and paleo-seasonal insights, including an δ18O-inferred annual seawater temperature range of ~ 5°C in the Channel Islands. Collectively, stable isotope data from mussels revealed both millennial-scale isotopic variability indicative of Holocene warm-cool oscillations and an east-west temperature gradient characteristic of the modern-day Channel Islands. However, M. californianus shells exhibited highly variable intra-individual δ18O values depending on micro-environment and ontogeny, complicating the use of aggregated stable oxygen and carbon isotope data from many individuals as an annually resolved climate proxy. Finally, I investigated changes in shell morphology, growth banding, and microstructure over the twentieth century in M. californianus shells from the southern portion of the California Current System (Santa Barbara through Baja California Sur). Shell thickness, morphology, the percentage of calcite-rich light bands, and the contrast between dark-light banding remained unchanged throughout all study sites in southern California and the Baja California peninsula. It is likely that southern populations of M. californianus are adapted to warmer conditions, while mussels from regions farther north in the California Current System may be more susceptible to warming waters. Mytilus californianus is a complex yet useful archive of environmental variability. Its shell records its environment over seasonal to millennial scales, depending on a variety of factors such as ontogenetic age, tidal position, and the sampling technique. I conclude that M. californianus can serve as a valuable record when multiple approaches are applied in tandem: analysis of the growth band pattern, ontogenetic stable isotope profiles, shell morphometrics, and microstructural imaging in one individual, and then across multiple individuals from many sites through time.

In late 2019, at multiple hatcheries in California’s Central Valley (CCV), offspring of recently spawned fall-run Chinook salmon (Oncorhynchus tshawytscha) exhibited abnormalities in swimming, lethargy, and high early life-stage mortality; the combination of these symptoms is commonly referred to as thiamine deficiency complex (TDC). The cause of thiamine deficiency in Pacific salmonids is hypothesized to be due to a lack of diet heterogeneity and reliance on northern anchovies (Engraulis mordax), containing high levels of thiaminase, a thiamine-cleaving enzyme. Of CCV’s four runs, the endangered Sacramento River winter-run Chinook salmon (WRCS) is perhaps the most vulnerable to thiamine deficiency as any additional stressor will exacerbate current threats to survival. The goal of this study was to evaluate the effect of thiamine supplementation in pre-spawn WRCS females on their offspring egg thiamine concentrations, survival, prevalence of TDC-related symptoms, and physiological performance and behavioral traits. Sixty female WRCS at Livingston Stone National Fish Hatchery were randomly administered either a thiamine injection (n=33; 500 mg/ml thiamine hydrochloride) at a dose of 50 mg/kg body weight or a sham injection (n=27; sterile saline solution) at a volume of 0.127 ml/kg body weight. After spawn, a subset of fertilized eggs from each female were analyzed for thiamine concentration. Eyed embryos were transferred to the University of California, Davis and kept for observations of TDC, survival, and to assess the effects of maternal thiamine treatments on offspring physiology and behavior. Upper thermal tolerance, routine metabolic rate, spontaneous swimming activity, boldness, and anti-predator responses were evaluated in swim-up fry. On average, total egg thiamine concentrations were 5.02 and 34.91 nmol/g for untreated (n=27) and thiamine treated (n=33) females, respectively. Mortality rate of offspring from untreated females averaged 32.97 ± 0.33 %, with rates ranging from 0 to 100%, while offspring from thiamine treated females had a mean mortality rate of less than 1%. Using a binomial logistic regression model, we predicted that a mean total egg thiamine concentration of ~5 nmol/g supports 95% survival within a family (EC95). There were no statistically significant effects of maternal treatment on any of the physiological or behavioral metrics assessed in this study. Overall, we recommend the administration of supplemental thiamine to increase thiamine concentrations past the threshold at which TDC symptoms are commonly observed; however, additional research should be conducted to further examine potential latent effects of thiamine deficiency in Pacific salmonids.

This project is directed towards implementing aspects of the tidewater goby recovery plan in coordination with, and funded by, the US Fish & Wildlife Service (USFWS) through a Section 6 Cooperative Agreement awarded to the University of California, Los Angeles on May 15, 2015. The primary focus of this dissertation was to developed a quantitative framework to complete a metapopulation viability analysis (MVA) for the endangered tidewater gobies in the genus Eucyclogobius. Modeling tidewater goby metapopulation dynamics is an essential component in constructing long-term management plans rangewide throughout the California Coast. This dissertation examines more closely how these dynamics affect viability, connectivity, and long-term persistence of tidewater goby metapopulations throughout the California coast. In the first chapter of this dissertation, I conducted annual population surveys (2014, 2015, and 2017-2018) in 117 estuaries and lagoons to assess the current health and status of the tidewater gobies in five of the six Recovery Units, spanning from Bodega Bay to San Diego, CA. This massive effort has provided continuous coastal surveys over four years, and over 300 observations, which helped create the framework for a robust and comprehensive presence/absence dataset to help inform metapopulation management and recovery actions. In the second chapter of this dissertation collated all existing rangewide occupancy data, metapopulation descriptors, wetland site characteristics, and repository specimen collections into an open access database. This database will provide critical information relative to the federally endangered tidewater gobies and help inform the metapopulation viability analysis model developed in this study, as well as support continued research on the conservation and management of these incredible fish species and the coastal wetland ecosystems they inhabit. In the third chapter of this dissertation I review the general biology, conservation status, habitat impacts, and metapopulation dynamics of the northern tidewater goby (Eucyclogobius newberryi) and southern tidewater goby (Eucyclogobius kristinae). In addition, I demonstrate the effectiveness of a Bayesian approach to provide a flexible method to generate metapopulation viability analyses and provide a detailed summary of the MVA model framework, including limitations, required corrections, and future amendments that need to be addressed in order to meet the recovery criterion envisioned in the recovery plan.

The biodiversity of terrestrial and aquatic communities is driven by the ability of species to successfully disperse to and persist in different habitats. For many marine fishes, dispersal occurs via a planktonic larval form that resides in the surface layer of the ocean for a period of days to months before moving to juvenile habitats and metamorphosing. The period from hatching to soon after settlement is a critical period for fish, as it features high mortality rates. In this dissertation, I investigate selective factors that influence larval dispersal, biogeography, and population persistence in the Eastern Pacific. In Chapter 1, I examined whether morphology of larval eels (order Anguilliformes) can predict larval geographic range, and found that morphological traits of intermediate-stage larvae predicted larval latitudinal range, as leptocephali with larger relative predorsal lengths and snout-to-anus lengths exhibited larger larval ranges. In Chapter 2, I used RAD sequencing to examine genetic structure of California morays (Gymnothorax mordax) and found that California morays exhibit local adaptation in the face of high gene flow, with selection likely taking place primarily during the late larval or early juvenile period. In Chapter 3, I used highly quantitative methods to test if skin coloration of California morays around Catalina Island, CA were correlated with their habitats. I found that eels were yellower and lighter in sandy habitats and that countershading (surprising for a benthic, crevice-dwelling fish) was present on the head and tail. We hypothesize that selection on coloration is also occurring during the first few years after settlement. In Chapter 1, I used a long-term west coast ichthyoplankton dataset to examine what environmental factors are influencing larval distributions of five commercially-important taxa of fishes, as well as larval fish overall: Pacific sanddab (Citharichthys sordidus), California sheephead (Semicossyphus pulcher), cabezon (Scorpaenichthys marmoratus), rockfishes (Sebastes spp.) and sablefish (Anoplopoma fimbria). I found that Bayesian hierarchical modeling is an effect method to model larval fish abundance, and that sea surface height was the strongest environmental covariate.

Sunscreen products contain chemicals such as oxybenzone or minerals such as titanium dioxide (TiO2) and zinc oxide (ZnO), which are a threat to marine biota and especially to coral reefs. Mineral sunscreens are being marketed as “reef-safe”; however, their impacts on marine organisms are not well understood. The aim of my thesis was to evaluate the effects of oxybenzone, TiO2, and ZnO on photophysiological properties of sea anemone Anthopleura elegantissima. This invertebrate belongs to the phylum Cnidaria and is a close relative to reef-building corals. Anemones were exposed to three environmentally relevant concentrations of oxybenzone, TiO2, and ZnO (nominally, 0.01 microgram/L, 0.1 microgram/L, and 1 microgram/L) for 21 days, followed by seven days of recovery in the absence of sunscreen ingredients. Throughout this 28-day period, measurements of fluorescence intensity and photosynthetic efficiency were taken as proxies for anemone photophysiology. The sunscreen ingredients did not seem to affect either parameter over the course of the experiment. However, analyses of seawater samples using inductively coupled plasma-mass spectrometry (ICP-MS) revealed prominent mismatches in the concentrations of TiO2 and ZnO compared to the target values, including much higher concentrations in the controls than in treatment samples. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis failed to detect oxybenzone. Overall, the unexpectedly high TiO2 and ZnO concentrations measured in the experimental aquarium coupled with oxybenzone analysis issues prevented reaching conclusions about their potential toxicity on anemone photophysiology. These factors must be considered for future studies aiming to assess potential toxic effects of sunscreen compounds on marine life.

Baited remote underwater video systems (BRUVs) have become a valuable method for observing large bodied marine organisms such as sharks. These systems provide several advantages over traditional methods for obtaining species distribution information, which is needed for effective management and conservation of coastal marine habitats. BRUVs are mainly utilized for assessing the distribution and abundance patterns of single species and the effects of environmental factors on these patterns (Bond et al. 2012; De Vos et al. 2015), however opportunities exist for expanded analysis from these rich collections of data. I used data from BRUV surveys within four regions of the Florida Keys to assess the co-occurrence patterns of sharks and rays, employing a method that expands on the utility of BRUVs to explore questions at the community level. I found no evidence to suggest that groups of species were gathering or avoiding each other more than expected. In species pairwise analysis, I found the pairing of specific species consistently co-occurring for common prey or habitat preference. The findings of this study will contribute additional knowledge to the work of MacNeil et al. (2020) in their effort to assess the conservation status of reef associated sharks and rays worldwide.

The red alga, Asparagopsis taxiformis, has recently been recognized for its unique ability to drastically reduce methane emissions from livestock. The main obstacle in using this seaweed is the complete lack of commercially available A. taxiformis. Little is known about how to develop large-scale cultivation systems for this red alga and the factors that influence its performance. This study examined the effect of the key factors including temperature and CO2 concentration, on the growth, photophysiology and the concentration of bromoform, the secondary metabolite responsible for methane reduction in A. taxiformis. A series of single and multifactor closed culture experiments, conducted on A. taxiformis collected, isolated, and cultured in southern California, identified the temperature and CO2 concentration required to optimize growing conditions. The findings indicate that through environmental control and addressing limiting factors, significant increases in biomass production can be achieved, making A. taxiformis a viable species for large-scale cultivation.

Sandy Point National Wildlife Refuge (SPNWR), located in St. Croix U.S. Virgin Islands (USVI), is a known hotspot for nesting sea turtles; however, a full analysis of green turtle (Chelonia mydas) nesting trends has not been conducted until this study. Green turtle nesting activities have been documented since the start of the sea turtle monitoring effort at SPNWR in the early 1980s. These data were digitally entered, compiled, and standardized before being analyzed. Primarily using generalized additive models, Chelonia mydas activities were analyzed to determine trends over time by looking at three time periods of data collection: the entire time frame of 1982-2020, 2005 to 2020, and peak season (August and September) counts for all years. In addition, chi-squared tests were conducted to determine if green turtles have location preferences for nesting and overall activities. Over all examined time periods, increasing trends in both nests and total activities were noted, demonstrating the possible effectiveness of conservation efforts. The North Beach at SPNWR had the highest numbers of activities and nest counts, as well as the highest nesting success rate of the three beaches (North, West, South), likely due to its relative physical and geological stability. Although a small population, Sandy Point’s nesting trends are increasing significantly more than those of similar nesting beaches in the region. Overall, the observed increasing nesting trends demonstrate that SPNWR’s green turtle population seems to be recovering in numbers; however, conservation efforts must continue in order to see these trends persist.