Comparison of bioconcentration and kinetics of GenX in tilapia Oreochromis mossambicus in fresh and brackish water.

Contaminants of emerging concern (CEC) are a broad suite of chemicals commonly found in the environment, aquatic organisms and even drinking water. They include pharmaceuticals, personal care products, industrial chemicals and compounds added to consumer products. The CEC ammonium 2,3,3,3-tetrafluoro-2-heptafluoropropoxy propanoic acid, which is more commonly known as generic name GenX, is a replacement of common processing aid longer chain perfluorinated compounds (PFAS) due to a manufacturing shift in 2002 following the EPA stewardship program of 2015/16 in USA (USEPA, 2006). However, recently reported in North Carolina drinking water, GenX raising concerns about its accumulation in aquatic organisms, both wild and cultured, which could be a pathway for human exposure. To examine GenX accumulation and potential for human exposure, tilapia (Oreochromis mossambicus) fingerlings were dosed with GenX for up to 96 h in fresh (0 ppt) or brackish (16 ppt) water to determine uptake and bioconcentration. Depuration values were also determined after a 96 h exposure followed by 96 h without exposure. Bioconcentration was in decreasing order of plasma > liver > carcass > muscle, with higher distribution to liver followed by carcass and muscle. Muscle was found to have the highest half-life (1278 h) followed by carcass (532 h), plasma (106 h), and liver (152 h). The rate of uptake and depuration was positively affected by the salinity. As bioconcentration in all tissues increased with increasing salinity, this may raise concern for marine organisms and human exposure.

An analysis of U.S. wastewater treatment plant effluent dilution ratio: Implications for water quality and aquaculture.

Wastewater discharge and surface flow data from 2007 to 2017 was used to calculate wastewater dilution factors (WWDF) for U.S. Geological Society hydrologic unit codes (HUC) in the contiguous U.S. HUC 10-year average WWDF values generally increased from the east coast (HUC 1-3: WWDF range 125-466) as you move west to the Mississippi River (HUC 7, 8, 10: 1435-1813) before further declining moving west (HUC 13-18: 7-908), particularly in the California (HUC 18: 9) and southwestern states (HUC 13-16: 7-351). Within HUCs, watersheds with higher population centers had lower WWDF values. This population effect on WWDF was greater in drier regions (e.g. Southwestern U.S.) or during drought. This is particularly pronounced in the regions of the Southwest and West where populations are growing in an already water limited region. Moderate WWDF improvement was observed and projected through 2022 in these regions. A few areas of the country where surface water is used for aquaculture overlap with areas of low (<2) WWDF, but it is not widespread for the period examined. With continued population growth and the intensification of climate change, the proportion of treated wastewater effluent in surface waters may grow and potentially influence users of that water, but over the 10-year period examined WWDF values were relatively stable or improving for most regions of the contiguous U.S.

Diseases of oysters Crassostrea ariakensis and C. virginica reared in ambient waters from the Choptank River, Maryland and the Indian River Lagoon, Florida.

To assess potential benefits and liabilities from a proposed introduction of Asian Suminoe oysters, susceptibilities of exotic Crassostrea ariakensis and native C. virginica oysters were compared during exposures to pathogens endemic in temperate, mesohaline waters of Chesapeake Bay and sub-tropical, polyhaline Atlantic waters of southern Florida, USA. Cohorts of diploid, sibling oysters of both species were periodically tested for diseases while reared in mesocosms receiving ambient waters from the Choptank River, Maryland (>3 yr) or the Indian River Lagoon, Florida (10 to 11 mo). Haplosporidium sp. infections (e.g. MSX disease) were not detected in oysters from either site. Perkinsus sp. infections (dermo disease) occurred among members of both oyster species at both sites, but infections were generally of low or moderate intensities. A Bonamia sp. was detected by PCR of DNAs from tissues of both oyster species following exposure to Florida waters, with maximum PCR prevalences of 44 and 15% among C. ariakensis and C. virginica oysters respectively during June 2007. Among C. ariakensis oysters sampled during April to July 2007, a Bonamia sp. was detected in 31% of oysters by PCR (range 11 to 35%) and confirmed histologically in 10% (range 0 to 15%). Among simultaneously sampled C. virginica oysters, a Bonamia sp. was detected in 7% by PCR (range 0 to 15%), but histological lesions were absent. Although this is the first report of a Bonamia sp. from Florida waters, sequences of small subunit (SSU) rDNA and in situ hybridization (ISH) assays both identified the Florida pathogen as Bonamia exitiosa, which also infects oysters in the proximate waters of North Carolina, USA.

Differential fertilization success between two populations of eastern oyster, Crassostrea virginica.

Identification of mechanisms promoting prezygotic reproductive isolation and their prevalence are key goals in evolutionary biology because of their potential role in speciation. In marine broadcast-spawning species, molecular interactions between gamete surface proteins are more important than mating behavior for determining reproductive compatibility. Evidence for differential fertilization capacity has been reported from experiments utilizing competing sperm from two males sampled within populations and between species, but to our knowledge conspecific populations that might have diverged in allopatry have never been tested on the basis of sperm competition. In the present study, the gametic compatibility and embryo survivorship from matings between two allopatric populations of Crassostrea virginica, the eastern oyster, on either side of a genetic step cline were investigated. Fertilization success, embryo survival, and paternity data all indicated an absence of strong reproductive barriers between the two oyster populations, implicating other mechanisms for maintenance of the cline step. Sperm from northern male oysters showed a tendency to produce more larvae than expected when competing with sperm from southern male oysters. Although the northern male advantage was not strong, the trend implies that long-distance dispersal across the step cline might more successfully result in north-to-south gene flow than the reverse, providing a mechanistic hypothesis explaining the asymmetric cline shape.

Are filtration rates for the rough tunicate Styela plicata independent of weight or size?

The filtration rate of the rough tunicate Styela plicata was determined as an aid for potential use as a bioremediator of algae and bacteria contamination in estuarine waters. Filtration rates were calculated hourly over a period of six hours for tunicates (16.8 to 57.8 grams) exposed to two targeted concentrations (10(5) and 10(6) cells mL(-1)) of the microalgae Nannochloropsis sp. (n = 7 per treatment) and the bacteria Escherichia coli (n = 6 per treatment). Filtration rates for individual tunicates exposed to microalgae differed as much as 3520 mL hr(-1) within an hour and 2349 mL hr(-1) with bacteria. However, the average filtration rate of tunicates exposed to microalgae at 10(5) cells mL(-1) was 3065 mL hr(-1) animal(-1)(+/- 1284 mL hr(-1) s.d.), 3252 mL hr(-1) animal(-1) (+/- 1039 mL hr(-1) s.d.) at 10(6) cells mL(-1) and 3158 mL hr(-1) animal(-1) when combined. The average filtration rate with bacteria at 10(5) cells mL(-1) was 4654 mL hr(-1) animal(-1) (+/- 810 mL hr(-1) s.d.), 2296 mL hr(-1) animal(-1) (+/- 1460 mL hr(-1) s.d.) at 10(6) cells mL(-1) and 3475 mL hr(-1) animal(-1) when combined. There was no relationship between average hourly filtration rate and whole animal weight (r(2) = 0.0001) or dry organ weight (r(2) = 0.0067) indicating that filtration rate should not be reported on a live or dry weight basis. It is suggested that averaging the filtration rate of a population of animals over time would yield a more accurate value, especially for use in modeling of bioremediation effects.