Fundulus Grandis Research Articles

Plasticity, repeatability and phenotypic correlations of aerobic metabolic traits in a small estuarine fish.

Standard metabolic rate (SMR), maximum metabolic rate (MMR), absolute aerobic scope (AAS) and critical oxygen tension (Pcrit) were determined for the Gulf killifish, Fundulus grandis, an ecologically dominant estuarine fish, acclimated to lowered salinity, elevated temperature and lowered oxygen concentration. Acclimation to low salinity resulted in a small, but significant, elevation of Pcrit (suggesting lower tolerance of hypoxia); acclimation to elevated temperature increased SMR, MMR, AAS and Pcrit; acclimation to low oxygen led to a small increase in SMR, but substantial decreases in MMR, AAS and Pcrit Variation in these metabolic traits among individuals was consistent and repeatable when measured during multiple control exposures over 7months. Trait repeatability was unaffected by acclimation condition, suggesting that repeatability of these traits is not context dependent. There were significant phenotypic correlations between specific metabolic traits: SMR was positively correlated with MMR and Pcrit; MMR was positively correlated with AAS; and AAS was negatively correlated with Pcrit In general, within-individual variation contributed more than among-individual variation to these phenotypic correlations. The effects of acclimation on these traits demonstrate that aerobic metabolism is plastic and influenced by the conditions experienced by these fish in the dynamic habitats in which they occur; however, the repeatability of these traits and the correlations among them suggest that these traits change in ways that maintain the rank order of performance among individuals across a range of environmental variation.

Production of Non-Toxic Biosurfactant – Surfactin – Through Microbial Fermentation of Biomass Hydrolysates for Industrial and Environmental Applications

Abstract The economically viable large-scale production of the pure isoforms of the surfactin biosurfactants, involving bacterial – Bacillus subtilis – fermentation of biomass hydrolysate feedstock, relies on the types of bacterial strains, optimization of the fermentation processing parameters, differences in the composition of the carbon and nitrogen in the bacterial media, and the chromatography techniques used for isolation of the isoforms. Here, we biosynthesized the surfactin isoforms in their mixture forms through fermentation of biomass hydrolysates at 2 wt.% carbohydrate content. The surfactin isoforms were assessed for their surface-active properties and toxicity. The enzyme hydrolysates considered were from switchgrass, soyhull (fiber), alfalfa, and bagasse. The isoform mixtures obtained after fermentation of the hydrolysates and, glucose as a control, were concentrated using chromatography columns, and characterized for molecular weights (MWs) and relative distribution using LCMS. The isoform mixtures, obtained in different fermenters (5- and 15-L) and, for different hydrolysates, invariably constituted 5 isoforms with MWs as 992.6, 1006.6, 1020.6, 1034.6, 1048.6, 1062.6 m/z amu, with their relative proportions as 6, 24, 35, 24, and 10 weight % respectively. The surface tension values of all these isoforms, in the absence of electrolytes and at 12 ppt salinity, were similar: 37 (pH 6.5) and 31 (pH 9.5) mN/m. Furthermore, the emulsification index values for the isoforms were also similar: Dispersant-to-Oil ratio as 1:20. The LC50 for Gulf killifish, Fundulus grandis for these surfactin isoforms ranged between 10 and 20 mg/L; a microbially-produced surfactin variant FA-Glu (Fatty acid Glutamate) was least toxic with LC50 at ∼100 mg/L. Thus, the surfactin synthesis approach adopted here suggested that pure (>95 wt.%) non-toxic isoforms of surfactin biosurfactants can be produced in the forms of their mixtures with surface-active properties similar to those of the pure forms of the surfactin isoforms.

Simultaneous estimation of dispersal and survival of the gulf killifish Fundulus grandis from a batch-tagging experiment

Simultaneous estimation of dispersal and survival of the gulf killifish Fundulus grandis from a batch-tagging experiment

Combined effects of salinity, temperature, hypoxia, and Deepwater Horizon oil on Fundulus grandis larvae

Oil spills have polluted the marine environment for decades and continue to be a major source of polycyclic aromatic hydrocarbons (PAHs) to marine ecosystems around the globe, for example during the 2010 Deepwater Horizon spill. Although the toxicity of PAHs to fish has been well studied, their effects combined with abiotic stressors are poorly understood. The goal of this study was to describe the combined impacts of crude oil and environmental stressors on fish larvae, a sensitive life stage. Gulf killifish (Fundulus grandis) larvae (<24 h post-hatch) were exposed for 48 h to high energy water accommodated fractions (HEWAF; total PAHs 0–125 ppb) of Macondo oil from the Deepwater Horizon spill under different combinations of environmental conditions (dissolved oxygen 2, 6 ppm; temperature 20, 25, 30 °C; salinity 3, 10, 30 ppt). Even under optimal environmental conditions (25 °C, 10 ppt, 6 ppm) larval survival and development were negatively affected by PAHs, starting with the lowest concentration tested (∼15 ppb). Hypoxia and high temperature each increased the adverse effects of HEWAF on development and mortality. In contrast, salinity had little effect on any of the endpoints measured. Importantly, expression of the detoxifying gene cyp1a was highly induced in PAH-exposed larvae under normoxic conditions, but not under hypoxic conditions, potentially explaining the enhanced toxicity observed under hypoxia. This work highlights the importance of considering how suboptimal environmental conditions can exacerbate the effects of pollution on fish early life stages.

Evolution to the rescue.

A study in Science uses experimental and population genomic approaches to examine the molecular underpinnings of evolved pollution resistance in Gulf killifish.

Influence of salinity and pH on bioconcentration of ionizable pharmaceuticals by the gulf killifish, Fundulus grandis

Estuaries routinely receive discharges of contaminants of emerging concern from urban regions. Within these dynamic estuarine systems, salinity and pH can vary across spatial and temporal scales. Our previous research identified bioaccumulation of the calcium channel blocker diltiazem and the antihistamine diphenhydramine in several species of fish residing in multiple urban estuaries along the Gulf of Mexico in Texas, where field-measured observations of diltiazem in fish plasma exceeded human therapeutic plasma doses. However, there remains a limited understanding of pharmaceutical bioaccumulation in estuarine environments. Here, we examined the influence of pH and salinity on bioconcentration of three pharmaceuticals in the Gulf killifish, Fundulus grandis. F. grandis were exposed to low levels of the ionizable pharmaceuticals carbamazepine, diltiazem, and diphenhydramine at two salinities (5 ppt, 20 ppt) and two pH levels (6.7, 8.3). pH influenced bioconcentration of select weak base pharmaceuticals, while salinity did not, suggesting that intestinal uptake via drinking does not appear to be a major exposure route of these pharmaceuticals in killifish. Compared to our previous pH dependent uptake observations with diphenhydramine in the fathead minnow model, killifish apparent volume of distribution values were markedly lower than fatheads, though killifish bioconcentration factors were similar at high pH and four fold higher at low pH than freshwater fish. Advancing an understanding of environmental gradient influences on pharmacokinetics among fish is necessary to improve bioaccumulation assessments and interpretation of toxicological observations for ionizable contaminants.

Egg Production of Gulf Killifish Is Dependent on Broodstock Rearing Density but Not Spawning Substrate Surface Area

AbstractThe Gulf Killifish Fundulus grandis is a popular baitfish for recreational fisheries and is a candidate for commercial‐scale culture; however, its relatively low fecundity compared to other baitfish presents a production challenge. Egg output in relation to broodstock densities and spawning mat surface areas was evaluated in recirculating aquaculture systems (RASs). In experiment 1, broodstock were stocked at two densities (45 and 90 fish/m³), with eggs collected three times per week for 8 weeks. Broodstock (15–17 g) that were held at 45 fish/m³ had greater reproductive output (3.93 eggs·female−1·d−1) than broodstock that were held at 90 fish/m³ (2.22 eggs·female−1·d−1). However, there was no difference between the number of eggs per collection (1,005 and 1,107 eggs per 3,600‐L tank) or total egg production (23,202 and 25,802 eggs per 3,600‐L tank), indicating that reproductive output was limited by another factor, such as available spawning substrate. Therefore, in experiment 2, broodstock (12–16 g) were stocked at a density of 100 fish/m³ in all tanks and were held for 8 weeks with one of three spawning mat (Spawntex) surface areas: 4,500 cm2 (one tier), 9,000 cm2 (two tiers), or 13,500 cm2 (three tiers). Reproductive output was 2.12, 2.27, and 2.21 eggs·female−1·d−1 for the one‐tier, two‐tier, and three‐tier treatments, respectively, with no differences among treatments. There was also no among‐treatment difference in the number of eggs per collection (1,724, 1,858, and 1,794 eggs/tank) or in the total number of eggs collected (27,587, 29,728, and 28,704 eggs/tank), suggesting that increasing the surface area of spawning material does not increase egg production. Therefore, a stocking density of 45 fish/m³ and a spawning mat surface area of 4,500 cm2 in commercial‐scale RAS broodstock tanks result in similar egg production compared to a higher stocking density and greater spawning mat surface area.

The influence of salinity on the toxicity of Corexit at multiple life stages of Gulf killifish

Following the Deepwater Horizon oil spill, approximately 7 million liters of the dispersant Corexit 9500A were released to promote oil biodegradation by breaking up surface oil slick formation. This process is accomplished via amphipathic anionic surfactants within dispersants that facilitate the mixing of aqueous and lipid phases. However, the amphipathicity of Corexit may also cause it to interact with biological membranes like the gill, impairing gill function and ultimately disrupting physiological processes mediated by it, such as osmoregulation. The goal of this study was to investigate the osmoregulatory effects and toxicity of Corexit in Gulf killifish. Killifish at the embryonic, larval, juvenile, and adult life stages were exposed to Corexit in water of different salinities to assess the interactive effects of ontogeny and salinity on Corexit toxicity. Corexit was not toxic to embryos except when exposed in hyperosmotic water where it had negligible effects; however, its toxicity to killifish increased dramatically following hatch, showing its greatest deleterious effects in adults. Corexit tended to increase sodium and chloride burdens in killifish when exposed in hyperosmotic waters and reduced whole-body and plasma ion concentrations in fish exposed to hypoosmotic waters. However, Corexit exposure at hyperosmotic salinities resulted in an increased differential accumulation of sodium over chloride as killifish matured. These findings suggest that Corexit may impair gill structure or alter specific components of osmoregulatory function, thus impacting osmoregulation in hypersosmotic and hypoosmotic waters, potentially impairing survival during osmotic challenges. Furthermore, the magnitude of these impacts continues to increase concomitant with gill ontogeny.

Validation of species specific otolith chemistry and salinity relationships

Strontium (Sr), barium (Ba), and their ratios to calcium (Ca) may be used as indirect proxies of salinity in otoliths, given that generally Sr:Ca is positively and Ba:Ca is negatively related to salinity. However, these relationships are non-linear, dependent on water chemistry, and vary among species. To determine if salinity reconstructions in northern Gulf of Mexico estuaries (nGOM) are possible for Red Drum (Sciaenops ocellatus) and Gulf Killifish (Fundulus grandis), and if ratios were similar between species, the relationships of Sr:Ca and Ba:Ca with salinity in water and otoliths were examined. Fishes were held at low (<1 psu), mid (10 psu), and high (30 psu) salinities established and maintained with water collected from local estuaries. Sr:Ca differed among all treatments for water and Gulf Killifish otoliths, increasing with salinity increases. Sr:Ca was lowest at the <1 psu treatment in Red Drum otoliths, remaining treatments did not differ, and was lower than Gulf Killifish at all treatments. Red Drum otolith and water Ba:Ca differed among all treatments, decreasing with increasing salinity, while Gulf Killifish otolith Ba:Ca was higher at the <1 psu than other treatments. Partition coefficients also differed among species and salinities. These results demonstrate that it should be possible to reconstruct salinities of Red Drum using otolith chemistry in nGOM estuaries. However, Gulf Killifish is not a good proxy species and species-specific validation, across a wide range of salinities, in the estuary of interest, should be conducted before salinity exposure is inferred from otolith elemental ratios.

Effects of passive integrated transponder tagging on cortisol release, aerobic metabolism and growth of the Gulf killifish Fundulus grandis.

The effects of passive integrated transponder (PIT) tagging on cortisol release, standard metabolic rate (SMR) and daily specific growth rate (GS ) were evaluated in the Gulf killifish, Fundulus grandis, a small estuarine fish native to the Gulf of Mexico. Cortisol release by individual fish was measured non-invasively prior to PIT tagging, immediately after tagging and once per week for 1 month following tagging. Within the first 2 h of tagging, cortisol release rates were significantly elevated compared with values measured prior to tagging and significantly higher than that of fish handled identically except not implanted with PIT tags. By 1 week after PIT tagging, cortisol release rates returned to control levels. SMR, determined by intermittent-flow respirometry and GS , defined as per cent change in body mass per day, were measured prior to PIT tagging and weekly for 1 month after tagging. Neither SMR nor GS was significantly different in tagged v. untagged fish for the duration of the study. One month after tagging, haematocrit, plasma cortisol, blood glucose and blood lactate did not differ between tagged and untagged individuals. Therefore, after a transient stress response that subsides within 1 week, PIT tagging had no significant effects on these physiological variables in F. grandis, validating its use as a method of marking this and other small fishes.

Standardizing the determination and interpretation of Pcrit in fishes.

The critical oxygen tension (Pcrit) for fishes is the oxygen level below which the rate of oxygen consumption (ṀO2 ) becomes dependent upon ambient oxygen partial pressure (PO2 ). We compare multiple curve-fitting approaches to estimate Pcrit of the Gulf killifish, Fundulus grandis, during closed and intermittent-flow respirometry. Fitting two line segments of ṀO2 versus PO2 produced high and variable estimates of Pcrit, as did nonlinear regression using a hyperbolic (Michaelis-Menten) function. Using nonlinear regression fit to an exponential (modified Weibull) function, or linear regression of ṀO2 versus PO2 at low PO2 , and determining Pcrit as the PO2 when ṀO2 equals standard metabolic rate (SMR) yielded values that were consistent across fish and among experimental trials. The magnitude of the difference in Pcrit determined by alternative calculation methods exceeded the differences determined in closed and intermittent-flow respirometry, highlighting the need to standardize analytical as well as experimental approaches in determining Pcrit.

The spatial scale of homogenisation and differentiation in Chihuahuan Desert fish assemblages

Abstract We examined riverine desert fish assemblages in the Chihuahuan Desert, U.S.A. at multiple spatial scales of similarity to assess long‐term changes to assemblage distinctiveness, identify individual species responsible for changes, and determine the importance of geographic context and species resolution in interpreting patterns of change. We used a well‐documented historical data set on fish distribution and abundance, and recent collections of fishes that provided a paired analytical design across 36 localities spanning nearly 3 decades. Patterns of faunal homogenisation and differentiation were assessed at basin‐wide, sub‐basin and river‐reach scales with species occurrence and relative abundance data. Individual species responses were examined to identify the drivers of assemblage change across time. Patterns of assemblage similarity varied across spatial scales and produced seemingly incongruous trends across time. Assemblage distinctiveness depended on the spatial extent of the analyses, the geographical structuring of the fish assemblages, and whether occurrence or relative abundance data were used. These dependencies led to interesting and conflicting patterns of homogenisation and differentiation. The Rio Grande sub‐basin showed strong homogenisation with convergence between upstream and downstream reaches that corresponded to declining water quality and quantity from the Rio Conchos in Mexico. In contrast, the Pecos River sub‐basin showed strong differentiation between upstream and downstream reaches that corresponded to the successful colonisation and spread of the non‐native gulf killifish (Fundulus grandis) in the upper reach, where water quantity and quality have declined. Spatial variability in fish assemblages and their degree of change from historical conditions were largely congruent with anthropogenic modifications to the flow regime and variability in the success of invasive gulf killifish in the basin. The use of species occurrence as opposed to relative abundance data, and the spatial scale of analysis are crucial choices in studies of faunal homogenisation and differentiation, and we have demonstrated how these choices lead to variable results for our study system. Our multi‐scale approach and examination of individual species responses identified the ultimate drivers of these differences and illustrated the importance of scale‐dependent effects and geographical context on patterns of assemblage distinctiveness, especially with regard to species invasion, species loss and relative abundance shifts.

Population genomics of Fundulus grandis exposed to oil from Deepwater Horizon

The April 2010 Deepwater Horizon (DWH) oil spill released over 4 million barrels of oil into northern Gulf of Mexico ecosystems. Due to the magnitude of the spill and observed effects from previous spills, the ecological impacts were predicted to be catastrophic. While negative effects of petroleum hydrocarbon exposure to fish have been documented at the organismal scale, most studies of fish assemblages have noted few, if any, DWH impacts. Our understanding of DWH effects is therefore limited by a disconnect in results reported at different organizational levels. We used population genomic tools to test hypotheses about population-level DWH impacts to Gulf Killifish (Fundulus grandis) in coastal Mississippi. Fundulus grandis is one of the most abundant marsh species in the northern Gulf of Mexico, and along with the sister species F. heteroclitus, has served as a model for toxicology research. We collected genotyping by sequencing data from four populations of F. grandis (two oiled and two not) to test predictions about DWH-related gene flow, demographics, genetic diversity and evidence of selection. Mississippi populations of F. grandis showed clear genetic structure, but there were few indicators (e.g. reduced genetic diversity, lower Ne estimates) consistent with large-scale mortality or migration related to DWH oil. Only one estimate of effective population size was reduced in oil-exposed populations and of the twenty outlier loci only two were in regions with potential adaptive significance (i.e., immune functions). While the toxic effects of oil on F. grandis at the organismal level is well established, the minimal impacts we detected to populations along the Mississippi coast likely reflects the complexity of the northern Gulf of Mexico and DWH oil spill. However, we do recognize that the patchiness of oil exposure and low genome coverage of the data limit our ability to conclude there were no DWH effects on these populations.

Repeatable Interindividual Variation in Hypoxia Tolerance in the Gulf Killifish, Fundulus grandis.

The capacity of fishes to tolerate low oxygen (hypoxia) through behavioral and physiological adjustments varies among species in a fashion that correlates with oxygen availability in their natural habitats. Less is known about variation in hypoxia tolerance within a species, but it is expressly this interindividual variation that will determine which individuals will survive during severe hypoxia. Here, we measured aquatic surface respiration (ASR) and loss of equilibrium (LOE), two common indexes of hypoxia tolerance of fishes, in gulf killifish, Fundulus grandis, subjected to multiple trials of a highly reproducible hypoxia protocol over a period of 6-8 wk. The time and [Formula: see text] at the first occurrence of ASR and the time and [Formula: see text] at LOE differed significantly among individuals in a repeatable fashion. This interindividual variation in ASR and LOE was significantly correlated with general body and gill morphology. The time to ASR was shorter and the [Formula: see text] at ASR was higher for fish with greater mass. After correcting for mass, fish with longer or more numerous gill filaments had longer times to ASR or LOE, respectively. Fish in better condition factor (heavier for their length) had lower [Formula: see text] at LOE. Repeatable interindividual variation in hypoxia tolerance, if genetically based, could influence the capacity of species to adapt as their habitats become increasingly threatened by aquatic hypoxia.

Predicting phototoxicity of alkylated PAHs, mixtures of PAHs, and water accommodated fractions (WAF) of neat and weathered petroleum with the phototoxic target lipid model.

The toxicity of petroleum can increase considerably after exposure to solar radiation, during which certain components in the mixture, including polycyclic aromatic hydrocarbons (PAHs), absorb light in ultraviolet and visible portions of the solar radiation spectrum. A phototoxic target lipid model (PTLM), previously developed to predict the phototoxicity of single PAHs, is validated for 4 species (Americamysis bahia, Rhepoxynius abronius, Daphnia magna, and Pimephales promelas) exposed to 12 compounds that are components of petroleum, including alkylated PAHs and dibenzothiophene. The PTLM is also used to predict the phototoxicity of binary and ternary mixtures of 3 PAHs, pyrene, anthracene, and fluoranthene, to A. bahia and Menidia beryllina. Finally, it is used to predict the toxicity of water accommodated fractions of neat and naturally weathered Macondo crude oil samples from the Deepwater Horizon oil spill sites. The Gulf of Mexico species, including A. bahia, M. beryllina, Cyprinodon variegatus, and Fundulus grandis were exposed to the oil samples under natural and simulated solar radiation. The results support the applicability of the PTLM for predicting the phototoxicity of petroleum. Environ Toxicol Chem 2018;37:2165-2174. © 2018 SETAC.

Correction to: Age validation and seasonal growth patterns of a subtropical marsh fish: the Gulf killifish, Fundulus grandis

The doi for the dataset mentioned in the acknowledgements is incorrectly cited as doi: https://doi.org/10.7266/N7SF2T32 . The correct doi for this dataset is https://doi.org/10.7266/N7NZ85M4 .

Combined effects of Deepwater Horizon crude oil and environmental stressors on Fundulus grandis embryos.

In the present study, we examined how sensitivity to oil changes in combination with environmental stressors in Fundulus grandis embryos. We exposed embryos (<24 h post fertilization) to a range of high-energy water accommodated fraction (HEWAF) concentrations (0-50 parts per billion [ppb] total polycyclic aromatic hydrocarbons [PAHs]) made from Macondo crude oil in conjunction with various environmental conditions (temperature: 20 and 30 °C; salinity: 3, 7, and 30 practical salinity units [PSU]; and dissolved oxygen: 2 and 6 mg/L). Endpoints included mortality, hatching rates, and expression of cytochrome p450 1a and 1c (cyp1a, cyp1c) in hatched larvae. There was 100% mortality for all fish under the 2 parts per million (ppm) dissolved oxygen regimes. For the 6 mg/L dissolved oxygen treatments, mortality and median lethal time (LT50) were generally higher in the 30 °C treatments versus the 20 °C treatments. Oil increased mortality in fish exposed to the highest concentration in the 20-3-6 (°C-PSU-mg/L), 25-7-6, and 30-30-6 conditions. Hatching was driven by environmental conditions, with oil exposure having a significant impact on hatching in only the 25-7-6 and 30-30-6 groups at the greatest HEWAF exposure. Expression of cyp1a was up-regulated in most treatment groups versus the controls, with cyp1c expression exhibiting a similar pattern. These data suggest interactive effects among temperature, salinity, and PAHs, highlighting a need to further assess the effects of oil exposure under various environmental conditions. Environ Toxicol Chem 2018;37:1916-1925. © 2018 SETAC.

Effects of stocking density on growth and survival of young Gulf killifish in recirculating aquaculture systems

ABSTRACTGulf killifish, Fundulus grandis, is a hardy marine baitfish with established rearing techniques in ponds and static pools, but there is little information about the use of recirculating aquaculture systems (RAS) for growing killifish.The current trial investigated the effects of stocking density on growth and survival of young killifish in RAS. Young fish (28-day posthatch) of 51.6 ± 0.9 mg (mean ± SE) were stocked at 2, 5, 8, and 11 fish/L in 31 L tanks in RAS with triplicate groups for 16 weeks. Cannibalism was a major problem in the study, which increased with increasing initial stocking density, affecting survival negatively. Survival decreased (P < 0.03) with increasing initial stocking density and culture period. At the end of the trial, the 2, 5, 8 and 11 fish/L initial stocking density reduced to 1.66, 1.42, 0.86, and 0.74 fish/L respectively. A significant linear relationship existed between the initial stocking density and weight (y = 0.077x + 2.3; R2 = 0.8; P = 0.003), whereas an inverse relationship occurred between initial stocking density and survival parameters (y = −9.43x + 97.4; R2 = 0.89; P < 0.001). From the trial, the optimum density for culturing young of Gulf killifish in RAS appears to be around two fish/L.

Polychlorinated biphenyl (PCB) contamination in Galveston Bay, Texas: Comparing concentrations and profiles in sediments, passive samplers, and fish.

The industrialized portion of the Houston Ship Channel (HSC) is heavily contaminated with anthropogenic contaminants, most prominent of which are the polychlorinated biphenyls (PCBs). This contamination has driven adaptive evolution in a keystone species for Galveston Bay, the Gulf killifish (Fundulus grandis). We investigated the geographical extent of PCB impacts by sampling 12 sites, ranging from the heavily industrialized upper portion of the HSC to Galveston Island. At each site, PCB concentrations and profiles were determined in three environmental compartments: sediment, water (polyethylene passive samplers), and fish tissue (resident Gulf killifish). We observed a steep gradient of PCB contamination, ranging from 4.00 to 100,000 ng/g organic carbon in sediment, 290-110,000 ng/g lipid in fish, and 4.5-2300 ng/g polyethylene in passive samplers. The PCB congener profiles in Gulf killifish at the most heavily contaminated sites were shifted toward the higher chlorinated PCBs and were highly similar to the sediment contamination profiles. In addition, while magnitude of total PCB concentrations in sediment and total fish contamination levels were highly correlated between sites, the relative PCB congener profiles in fish and passive samplers were more alike. This strong correlation, along with a lack of dependency of biota-sediment accumulation factors with total contamination rates, confirm the likely non-migratory nature of Gulf killifish and suggest their contamination levels are a good site-specific indicator of contamination in the Galveston Bay area. The spatial gradient of PCB contamination in Galveston Bay was evident in all three matrices studied and was observed effectively using Gulf killifish contamination as an environmentally relevant bioindicator of localized contamination in this environment.

Assessment of gonadal and thyroid histology in Gulf killifish (Fundulus grandis) from Barataria Bay Louisiana one year after the Deepwater Horizon oil spill

We examined gonads and thyroid glands of Gulf killifish (Fundulus grandis) 1yr after the Deepwater Horizon oil spill. F. grandis were trapped from two impacted sites in Barataria Bay (Bayou St. Denis, Bay Jimmy) and an un-impacted site in East Texas (Sabine Pass). The greatest number of F. grandis were collected at Sabine Pass. F. grandis collected at Bayou St. Denis were smaller and had smaller Fulton condition factor scores than fish collected at Sabine Pass. Sex ratios were biased roughly 2:1 in favor of females at Sabine Pass and Bayou St. Denis. Gonad-somatic index (GSI) in males from Sabine Pass was double that of fish from Bay Jimmy while germinal epithelium thickness of the testes was 2.7 fold smaller in males from the impacted site. GSI and oocyte diameters in females from Bayou St. Denis were significantly smaller than females from Bay Jimmy or the reference site. There were no differences in thyroid follicle cell height. While total polyaromatic hydrocarbons at the impacted sites were no different from the reference site, the impacted sites did have greater concentrations of benzo[a]pyrene in sediment pore water. The finding of smaller GSI and testicular germinal epithelium in males from an impacted site suggest that exposure to a combination of oil and dispersants may adversely impact testicular function.