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Future water quality challenges to aquaculture and influences on product safety
No full textConcerns about water quantity and quality are increasing due to climate change and population growth. Climate change is driving changes in evapotranspiration and precipitation patterns. This is exacerbated as population growth, particularly in arid and semi-arid regions, increases water extraction and consumption. After human consumption, water is treated and discharged to the environment, but generally at lower quality than what was originally extracted. This could cause trouble for consumers of surface waters. One such consumer is the aquaculture industry, which is growing to support human protein consumption demands, while depending on surface water.Aquaculture is growing both globally and within the U.S. (worldwide 9.2% yr-11990-2000 & 6.2% yr-12000-2012). Freshwater aquaculture in the U.S. is largely dependent on surface water (80.78%) compared to ground water sources (19.32%). Surface water sources are increasingly dominated or dependent on treated wastewater effluent, potentially influencing downstream uses. Wastewater effluent generally contains trace levels of anthropogenic compounds, typically referred to as contaminants of emerging concern (CEC), for which our knowledge of their impacts is still evolving. Therefore, the introduction of CEC in aquaculture from surface waters influenced by wastewater effluent is a potential concern for cultured fish health as well as for humans when consuming farmed fish. Studies were conducted to improve our understanding of future water resource quality and quantity in relation to the aquaculture industry and safety of farmed fish. Initially, wastewater effluent data was collected (e.g., USGS), consolidated, and analyzed (e.g., GIS) to understand its influence on surface water quantity and quality, which was utilized to project potential future water quality and quantity scenarios in the USA and its potential effect on aquaculture. This was followed by laboratory-based studies to quantify the bioaccumulation and depuration in tilapia of diltiazem, an ionizable calcium channel blocker, and GenX, a perfluorinated compound, at environmentally relevant concentrations. To broadly examine the extent of U.S. surface waters to dilute wastewater treatment plant (WWTP) effluent, data from wastewater discharge and surface flow from 2007-2017 was used to calculate a WWTP wastewater dilution factor (WWDF) within United Sates Geological Society (USGS) hydrologic unit code (HUC). A WWDF less than 10 indicates poor quality water when classified on <1 to >100 DF scale. The 4 HUCs with the lowest WWDF (i.e., <2) were located in the West or Southwest U.S. and were among the 10 HUCs with the highest proportional population growth from 2010-2016, with similar projections for the future. To identify the end water user impact, U.S. aquaculture farm area with WWDF < 2 was mapped. It was quantified at ~ 2.71% of total freshwater area, out of which 69% and 44% of the area was occupied by aquaculture farms with 100-and 1000-acre areas, respectively. Water availability for the contiguous U.S. was estimated for each HUC during 2015 using a model developed from the earlier analysis of water quantity and quality in the U.S. The Mississippi River generally served as a dividing line for surface water availability, with five of the six HUC regions with very low water availability (<24,000 L/D/Km2) residing in the west. These same areas also experience more drought as well as more severe droughts than regions in the east. In regions with lower surface water flows, water quality is more susceptible to the influence of wastewater effluent discharge, especially near large and growing population centers like San Antonio, Texas. A prediction model was established for this city, which found that from 2009-2017 wastewater effluent increased by 1.8%.
Diltiazem(DTZ)bioconcentrationanddepurationintilapiawasexaminedusingacontrolledtimesequence(maxtime=96hr)exposure(1μgL-1)andnon-exposure(maxtime=96hr)infreshwater.Fishcarcass,bloodplasma,liver,andmusclewereanalyzedinbothexposureanddepurationphases.Diltiazembioconcentrationwasgreatestinliver>plasma>carcass>muscle.Depurationratesweregreatestforliver>carcass>plasma>muscle.Thebiologicalhalf-life(t1/2)indicatesthatDTZtookthelongesttodepuratefrommuscleandleastfromtheliver,whichissimilarforthestablebioconcentrationfactor(BCFa)valueorder.Thet1/2ofDTZintilapiamusclewas18.8hrs,indicatingthecompoundisprocessedrelativelyquickly.Basedonthe96hrDTZuptakebytilapiafingerlingsinthisstudy,humanexposuretothehighestDTZmuscleconcentrationwouldbe~6ordersofmagnitudebelowthelowestdailyhumantherapeutic(120ppb)dose,resultinginverylowhumanexposure.
GenX (ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy))bioconcentrationanddepurationintilapiawasexaminedusingacontrolledtimesequence(maxtime=96hr)exposure(1μgL-1)andnon-exposure(maxtime=96hr)infreshwaterandbrackishwater(16ppt).GenXbioconcentration (BCFa) was greatest in plasma > liver > carcass > muscle, with higher distribution in liver compared to carcass and muscle. Bioconcentration in all tissues examined increased with increasing salinity, raising concern for euryhaline organisms. Muscle was found to have the highest t1/2followed by carcass, plasma, and liver. The rate of uptake and depuration was affected bysalinity. Fish muscle (fillet) GenX concentration at 96 hrs at 0 ppt was 0.14 ppb whereas at 16 ppt it was 0.312 ppb. Therefore, a fillet serving size of ~3.5 oz (100 g) would contain 14.0 μg GenX from freshwaterfish and 31.2 μg GenX from saltwater (16 ppt) fish. This would result in a single serving exposing a person to more than the subchronic oral reference dose of 0.2 ppb as recommended by U.S. EPA.
Water quality is a growing concern along with changing climate and increasing population. The projections and improved bioaccumulation models for farmed fish from this research will provide aquaculturists with knowledge to make pro-active management decisions regarding water quality in the future, while improving our general understanding of human exposure to CEC from nontraditional water use. It also helps to understand environmental exposure and ecological impacts of pharmaceuticals and other industrial chemicals for sustainable management of environmental quality, particularly in urbanizing ecosystems.Physical and Environmental SciencesCollege of Science and Engineerin
Presence of Plastics in the Gastrointestinal Tract of Sharks in Texas Bays
No full textPlastics in the marine environment have become an important topic in the recent decade due to its ubiquitous presence, long lasting impacts, and detrimental health effects. Plastics have been observed affecting marine organisms by causing gastrointestinal or respiratory blockages or tears. Other consequences of plastic ingestion include exposure to endocrine disrupting compounds, persistent organic pollutants, and toxic trace metals. Few studies have investigated the presence of plastics in shark gastrointestinal tracts, and nothing is known for sharks in Texas bays. This study assessed the presence, abundance, and type of plastics present in the gastrointestinal tracts (cardiac stomach, pyloric stomach, and spiral valve intestine) of three shark species [blacktip shark (Carcharhinus limbatus), bonnethead shark (Sphyrna tiburo), and bull shark (Carcharhinus leucas)] in four bays (Sabine Lake, Aransas Bay, Corpus Christi Bay, and Lower Laguna Madre) along the Texas coast using a stereomicroscope and Fourier transform infrared spectroscopy (FTIR). Young-of-the-year, juvenile, and adult individuals were examined in this study. Of the total number of sharks examined (n = 240) only eight individuals (two blacktip sharks, two bonnethead sharks, and four bull sharks) were found to contain plastic pieces, and a total of nine pieces of plastic were found. Each plastic piece was found in the cardiac stomach. Monofilament fishing line and hooks were commonly found, meaning that fishing practices, not plastic ingestion through diet is the main problem. The most frequently found polymers were polyethylene (PE) and nylon 6. Due to the low number of plastics found in these sharks, plastics do not appear to pose a threat to these species in these bay systems, however, future studies should include smaller fibers which were omitted from this study and investigate nanoplastics which could cross the gastrointestinal tract lining and be remobilized around the body.Biolog
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Effects of microplastic pollution on fish health using Japanese Medaka as a model
Get PDFMicroplastic pollution is of current public concern for global environmental health and of
relevance for aquaculture and fisheries. Microplastic ingestion has been shown to cause intestinal
damage, microbiota dysbiosis, and disturbed lipid and energy metabolism in fish. However, these
data resulted from exposures of adult fish at microplastic concentrations 2-7 times higher than
concentrations found in the environment. To determine the impact of microplastic ingestion on fish
health at environmentally relevant, chronic, low doses of microplastic fibers, Oryzias latipes larvae
and juveniles were exposed to five concentrations of polyethylene (PE) fibers for 21 days through
feed. Fish energy intake, growth & condition and reproductive output were assessed to determine
the overall impact on fish health. To assess energy intake, gut integrity was evaluated at the
molecular and cellular level. Relative gene expression of key digestive genes from gut tissue was
quantified using real time-quantitative polymerase chain reaction (RT-qPCR). An effect on
digestive gene expression potentially effecting nutrient absorption and antioxidant production was
indicated via a significant decrease of slc6a6 expression in larvae exposed to the highest
concentration. No significant molecular changes were observed in juvenile gut tissue. Gut
morphology was analyzed using histomorphological observations of the intestinal mucus layer and
cell types. No significant impairment to gut epithelial layers was observed in larvae or juveniles.
To assess growth & condition, Fulton’s condition factor, hepatosomatic index, and gonadosomatic
index were measured. No differences were observed in larval or juvenile growth. To assess
reproductive output, exposed fish were bred and fecundity, fertility and hatching rate were
evaluated. Fecundity and fertility were not affected by consumption of microplastic fibers at these
concentrations. However, hatching in the F1 offspring was delayed by 2-3 days upon
environmentally relevant PE exposure of juvenile fish. Significantly delayed hatching can impact
vi
overall offspring survivability and ultimately population recruitment. Comparisons of different
developmental stages allowed for identification of vulnerable developmental stages for microplastic
exposure; larvae were more susceptible to molecular changes due to PE exposure; however,
juveniles demonstrated organismal level effects via delayed egg hatching. This study is one of the
first to provide toxicological data on the risk of PE fiber ingestion during development stages of
fish. Results indicate no imminent threat to fish condition at current measured environmental levels
of microplastics; however, close monitoring of vital spawning grounds for commercially important
fishes is recommended.Life SciencesCollege of Science and Engineerin
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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Quantification of microplastic presence in Texas waterways and inflows to the Gulf of Mexico
No full textPlastics, first invented in the early 20th century, are long chain polymerized hydrocarbons. Plastics are a staple of everyday life; from packaging, to toys, to clothing, plastic has become a constant in day-to-day life. It is easy to see why, due to its structural stability, ability to withstand breakdown, and wide range of applications. Plastic’s prolific use has allowed for its entry to the environment at every level. Microplastics are plastic particles and fibers that are less than 5 millimeters in size. Microplastics originate as macroplastics which degrade to smaller sizes, or from products that are manufactured at this size. Research has been conducted to quantify microplastics in the Gulf of Mexico, in source waters of the Mississippi River, and in
some coastal areas. There is a paucity of data on microplastics in Texas coastal rivers and bays. The purpose of this project is to provide baseline data on the presence of microplastics in Texas waterways that feed into the Gulf of Mexico in 2019 to 2020. Water samples were collected at 19 locations from Galveston to the U.S., Mexico border. They were collected at
the water surface and 60% of the depth at the time of collection. All samples were filtered through a 0.45 μm, cellulose, membrane filter followed by visual sorting of suspected microplastics. A Fourier-transform infrared microscope (μFTIR) was used for materials confirmation. Microplastic concentrations across all sampled locations averaged 4.0 ± 2.9 microplastics per liter. Polyethylene Terephthalate was the most common microplastic found, accounting for 39% of microplastics. Polystyrene was 33%, while other material types were all less than 10% individually. Total loading to the Texas coastal zone was estimated at ~27 trillion
microplastics annually, equaling ~220 kg. The results of this study are expected to help regulators understand the scale and scope of microplastics pollution in coastal Texas and to help inform future waterway management decisions.Physical and Environmental SciencesCollege of Science and Engineerin
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Distribution of pesticides in groundwater and surface water flood-impacted unconnected communities in South Texas following Hurricane Hanna
No full textPesticides are a vital farming input as they help protect crops from pests and diseases for quality yields and high productivity. However, pesticides' high production, extensive use, and persistence are a potential risk for human health and ecosystems due to their leaching or runoff into the surface water (SW) and groundwater (GW). Over the years, there has been an increasing concern regarding the water quality of SW and GW next to farming areas, specifically after spills or industrial discharges, heavy rainfall, and intense storms. In the case of hurricanes, these cause deposition of contaminants from the atmosphere, disturbance and transport of the sediments in surface water bodies, surface run-off, and penetration of floodwaters to GW. In addition, pesticide degradation in the environment due to different biotic and abiotic transformation processes produces transformation products (TPs), sometimes even more toxic than the original compound. In July 2020, Hurricane Hanna severely damaged infrastructure and agriculture in many counties across the Rio Grande Valley. This area has the largest colonias in South Texas, predominantly Hispanic low-income semirural communities near the Texas-Mexico border that mainly rely on GW as a drinking water source. As part of this study, surface water and groundwater samples were collected from colonias in South Texas communities after hurricane Hanna for one year. The analytical approach involved solid-phase extraction (SPE) followed by suspect and target screening of pesticides using ultrahigh-pressure liquid chromatography (UPLC) coupled to a high-resolution Orbitrap Fusion Tribrid mass spectrometer system (OT-FTMS). The advantages of the state-of-the-art high resolution mass spectrometry allowed the accurate identification and quantification of pesticides using an in-house compound database of 308 pesticides for target screening. This is one of the most extensive studies that has screened and quantified over 200 pesticides in a single sample in the United States and, to my knowledge, is one of the largest in Texas. The results of eight monitoring sampling campaigns revealed the occurrence of 21 pesticides with minimum instrumental limit of detection (LOD) of 0.05 ng/mL and limit of quantification (LOQ) of 0.10 ng/mL. Six herbicides were the most detected compounds, followed by insecticides (5), fungicides (4), TPs (3), and a plant growth regulator (1). The most frequently detected compounds were atrazine, clothianidin, cycluron, DEA, dinotefuran, and norflurazon and those with the highest concentrations were clothianidin (211 ng/L), DEET (13,885 ng/L), and norflurazon (952 ng/L). In general, more compounds were detected in GW than in SW, except for atrazine and DEA. Atrazine in SW showed higher detections frequency (67%) than GW (15%) as well as DEA (GW = 6%, SW = 8%). DEET was the compound detected at the highest frequency in GW (74%) while atrazine was detected at the highest frequency in SW (67%). The leaching of pesticides to GW is a complex process and depends on the pesticide's chemical properties, characteristics of the soil, volatilization, climatic conditions of the site, plant uptake, and pesticide management practices. Mainly, pesticides with high leaching potential are more likely to be transported in groundwater beyond application area. In this study, clothianidin and norflurazon with high leaching potential showed significant concentrations in GW. This is one of the few studies able to survey more than 200 pesticides in the United States in general and in Texas specifically, using high resolution mass spectrometry. This work provides a baseline of the water quality for those communities that rely on GW as the primary source of drinking water supply. The occurrence of pesticides in GW demonstrates the vulnerability of the area and the need to continue monitoring the water quality in this region.Physical and Environmental SciencesCollege of Science and Engineerin
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From factory to table: Assessment of combined industrial pollution on three economically relevant fishes within the Matagorda Bay system of Texas: S. Ocellatus, C. Nebulosus, and P. Lethostigma
No full textMercury ranks as one of the top three toxic substances. Aquatic wildlife and humans face adverse health effects when exposed to it in the form of methylmercury. The mass output of hazardous waste has resulted in an EPA Superfund Site for mercury on the edge of Lavaca Bay, the northernmost subset of the Matagorda Bay system. Additionally, heavy release of pre-production resin pellets (nurdles) was discharged into the bay within the last two decades. Due to their chemical properties, there is potential for mercury to bind to the discharged pellets as well as typical debris seen in all environments. Sorption to plastic may allow for mercury to travel greater distances throughout the bay, resulting in higher mercury concentrations in the fish within this semi-closed system. A sample of 178 fish (Sciaenops ocellatus, n = 47; Cynoscion nebulosus, n = 85; and Paralichthys lethostigma, n = 46) was opportunistically collected from anglers fishing within the Matagorda Bay System. Muscle and liver tissue samples, as well as digestive tracts, were removed from each fish. Digestive tracts were dissected, removing any suspected plastic visible to the human eye (>1mm). Mercury concentrations (wet weight; µg g-1 ) of each tissue type and plastic found within the gut were measured in efforts to observe any trends in plastic consumed and mercury concentrations of the fish. No plastic debris (>1mm) was observed in the sampled digestive tracts, inhibiting the analysis of one of the objectives. The study determined mercury concentrations of three economically relevant fish, categorize them by FDA Consumer Advisory levels, and assess a factor of health via hepatosomatic index (HSI). Data from this study will be used to inform the public affected by the pollution in this area and can inform policy and regulations regarding safe consumption limits and reporting efforts.Physical and Environmental SciencesCollege of Science and Engineerin
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