{{Short description|Species of fish}} {{Use dmy dates|date=March 2017}} {{Speciesbox | image = Fundulus grandis.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 20 November 2021">{{cite iucn |author=Collette, B.B. |author2=Grubbs, D. |author3=Pezold, F. |author4=Tornabene, L. |author5=Chakrabarty, P. |author6=Robertson, R. |author7=Caruso, J. |author8=Carlson, J. |author9=McEachran, J.D. |author10=Brenner, J. |author11=Simons, J. |date=2019 |title=''Fundulus grandis'' |volume=2019 |article-number=e.T190111A86337744 |doi=10.2305/IUCN.UK.2019-2.RLTS.T190111A86337744.en |access-date=20 November 2021}}</ref> | taxon = Fundulus grandis | authority = Baird & Girard, 1853 | synonyms = *''Fundulus floridensis'' <small>Girard, 1859</small> *''Fundulus pallidus'' <small>Evermann, 1892</small> | synonyms_ref = <ref name = Fishbase>{{Fishbase|Fundulus|grandis|month=April|year=2019}}</ref> }} The '''Gulf killifish''' ('''''Fundulus grandis''''') is one of the largest members of the genus ''Fundulus''; it is capable of growing up to {{convert|7|in|cm}} in length, whereas the majority of other ''Fundulus'' reach a maximum length of {{convert|4|in|cm}}. Therefore, ''F. grandis'' is among the largest minnows preyed upon by many sport fish, such as flounder, speckled trout (''Cynoscion nebulosus''), and red drum (''Sciaenops ocellatus'').<ref name="ross" /> ''Fundulus'' derives from the Latin meaning "bottom," and ''grandis'' means "large".<ref name="boschung">{{cite book|last=Boschung|first=H.T.|title=Fishes of Alabama|year=2004|publisher=Smithsonian Books|location=Washington|page=736|author2=R. L Mayden}}</ref> The Gulf killifish is native to the Gulf of Mexico from Texas to Florida and the eastern coast of Florida and the Caribbean Sea in the Atlantic Ocean.<ref name="lee"/> Threats to the survival of the Gulf killifish include extreme changes in salinity, changes in temperatures, and toxic events such as the hypoxic dead zone in Louisiana and the Deepwater Horizon oil spill. The Gulf killifish is currently being used to test the effects of oil and oil dispersants <!-- specifically Macondo 252 crude oil and Corexit 9500, --> on the physiology of marine species affected by these substances. This is significant to conservation biology, because with the continued extraction of oil and other natural resources from North American waters, it has become increasingly important to understand the risks and consequences in worst-case scenarios, such as the Deepwater Horizon oil spill, and the lasting effects on the marine ecosystem.
==Description== ===Coloration=== ''Fundulus grandis'' has a unique coloration that separates it from other ''Fundulus'' species. First, the base color is a dull greenish above shading to lemon-yellow below.<ref name="simpson">{{cite journal|last=Simpson|first=D.G.|author2=G. Gunter|title=Notes on habitats, systematic characters and life histories of Texas salt water cyprinodonts |journal=Tulane Studies in Zoology |year=1956|volume=4|issue=4|pages=115–134}}</ref> Furthermore, the differences in coloration between males show much more vivid colors with silver flecking and noticeable striping; and females, which can appear olive to dull olive below if they grow big enough.<ref name="simpson"/> Additionally, stripes, spots, and different colors occur along the body structure. In the predorsal region are predorsal stripes, which may be present, but generally fade as the fish ages <ref name="reylea">{{cite journal|last=Relyea|first=K|title=A systematic study of two species complexes of the genus ''Fundulus'' (Pisces: Cyprinodontidae)|journal=Bulletin of the Florida State Museum, Biological Sciences |year=1983|volume=29|issue=1|pages=1–64 |url=https://ufdc.ufl.edu/UF00095803/00001 }}</ref> and occasionally predorsal spots.<ref name="hubbs1">{{cite journal|last=Hubbs|first=C.L. |author2=R.J. Edwards |author3=G.P. Garrett|title=An annotated checklist of freshwater fishes of Texas, with key to identification of species.|journal=Texas Journal of Science|year=1991|volume=43|issue=4|pages=1–56}}</ref> Also, small pearly spots are found along the side of the fish.<ref name="smith">{{cite book|last=Smith|first=C.L.|title=National Audubon Society field guide to tropical marine fishes of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda.|year=1997|publisher=Alfred A. Knopf, Inc., New York.|page=720}}</ref> The anal and lower half of the caudal region may be yellow or the anal, dorsal, and caudal regions may be darker in color with white splotches at the base.<ref name="simpson"/> Additionally, the coloration of the male fish changes when they are breeding.<ref name="ross">{{cite book|last=Ross|first=S.T.|title=The Inland Fishes of Mississippi.|year=2001|publisher=University Press of Mississippi, Jackson.|page=624}}</ref> In all, these males are deep blue dorsally, and have blue median fins with light blue spots and yellow-orange margins.<ref name="ross"/> However, in general, the Gulf killifish is characterized by its yellowish or pale belly, and darker back with many pale spots, mottling, and inconspicuous bars.<ref name="robins"/>
===Body structures=== More than 15 scale rows occur on the killifish's body between the pelvic fin and the isthmus, as well as 31 to 39 longitudinal scale rows.<ref name="hubbs2">{{cite journal|last=Hubbs|first=C. |author2=R.J. Edwards |author3=G.P. Garrett|title=An annotated checklist of freshwater fishes of Texas, with key to identification of species.|journal=Texas Journal of Science|year=2008|volume=43|issue=4|pages=1–87}}</ref> Additionally, an average of 17 to 20 individual scales are seen around the caudal peduncle.<ref name="ross"/> Also, 12 to 19 faint stripes are found along the side of the killifish.<ref name="simpson"/> The killifish also has five pairs of mandibular pores, which are sensory pores located on the underside of the lower jaw, part of the lateral line sensory system.<ref name="stevenson">{{cite book|last=Stevenson|first=H.M.|title=Vertebrates of Florida|year=1976|publisher=University Presses of Florida, Gainesville|page=607}}</ref> Around 9 to 12 gill rakers, 10 to 12 dorsal rays, 9 to 11 anal rays, and six pelvic rays are present.<ref name="ross"/>
The maximum length of the Gulf killifish is 18.0 cm,<ref name="smith"/> but it is usually around 10.4 cm in length. These fish are characterized by a blunt head and short snout.<ref name="robins">{{cite book|title=A field guide to Atlantic Coast fishes of North America.|url=https://archive.org/details/fieldguidetoatla00robi|url-access=registration|year=1986|publisher=Houghton Mifflin Company, Boston, MA.|author=Robins, C.R. |author2=G.C. Ray |author3=and J. Douglass}}</ref> The mouth is positioned nearly terminal and its lower jaw slightly projects outwards.<ref name="ross"/> <!-- explain However, the eyes of the Gulf killifish go fewer than 1.5 times in snout.<ref name="hubbs2"/> --> The position of the dorsal fin varies slightly among individuals, yet it generally originates anterior to the anal fin origin.<ref name="hubbs1"/> The anal fin of the killifish is rounded, with the base of the fin being more than half the length of its longest rays.<ref name="stevenson"/> The distance from the origin of the dorsal fin to the end of the hypural plate is usually less than the distance from the origin of the dorsal fin to the preopercle, yet occasionally these distances are equal due to the genetic variability among individuals.<ref name="hubbs2"/> An important characteristic of the fish is the length of the gill slit because it ultimately determines how much water can pass through the gills.<ref name="wilson">{{cite journal|last=Wilson|first=Jonathan M.|author2=Pierre Laurent|journal=Journal of Experimental Zoology|year=2002|volume=293|issue=3|pages=192–213|doi=10.1002/jez.10124|pmid=12115897|title=Fish gill morphology: inside out}}</ref> The anterior edge of a gill slit is motile, moving outward to allow water to exit, but closing to prevent reverse flow.<ref name="wilson"/> In Gulf killifish, the gill slit extends dorsal to the uppermost pectoral-fin ray.<ref name="hubbs1"/> The Gulf killifish is one of the largest killifish species to have a blunt head and short snout.<ref name="robins"/>
==Habitats== ===Types=== The Gulf killifish can survive in wide ranges of habitats because it is highly adaptive. These adaptions have changed over time through evolution, which have allowed for the increased survival of the Gulf killifish.<ref name="connor">{{cite book|last=Connor|first=J.V.|title=The Zoogeography of North American Freshwater Fishes|year=1986|publisher=John Wiley and Sons|location=New York, New York|page=866|author2=R.D. Suttkus}}</ref> These different habitats include estuarine, lowland, upland, coastal marshes, lagoons, rivers, and streams.<ref name="burgess">{{cite book|editor-last=Lee|editor-first=D. S.|title=Atlas of North American Freshwater fishes.|year=1980|publisher=N.C. State Mus. Nat. Hist.|location=Raleigh, NC|page=516|author=G. H. Burgess|chapter=Fundulis grandis}}</ref> However, the Gulf killifish spends the majority of the time around brackish water near coasts.<ref name="lee">{{cite book|last=Lee|first=D.S.|title=Atlas of North American freshwater fishes|url=https://archive.org/details/atlasofnorthamer00unse_0|year=1980|publisher=North Carolina State Museum of Natural History|location=Raleigh, NC |author2=C. R. Gilbert |author3=C. H. Hocutt |author4=R. E. Jenkins |author5=D. E. McAllister |author6=J. R. Stauffer Jr.|isbn=978-0-917134-03-6 }}</ref>
===Distribution=== The Gulf killifish is found in the Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea, and over the Southeast United States Continental Shelf.<ref name="robins"/> The normal range of Gulf killifish is from Texas to the western coast of Florida and from the east coast of Florida and throughout the Caribbean.<ref name="lee"/> These waters undergo several changes in water characteristics such as temperature, dissolved oxygen, and salinity, among many other variables that can have profound effects on the survival and abundance of the Gulf killifish.<ref name="connor"/>
===Salinity ranges=== Spending a lot of time near the coasts ensures that the Gulf killifish is able to survive various salinity ranges including fresh water because their habitats get influx of freshwater into the ecosystems normally.<ref name="crego"/> It is able to withstand salinity ranges from 0 to 76 ppt.<ref name="lee"/><ref name="crego">{{cite journal|last=Crego|first=G.J.|author2=M.S. Peterson|year=1997|title=Salinity tolerance of four ecologically distinct species of ''Fundulus'' (Pisces: Fundulidae) from the northern Gulf of Mexico.|journal=Gulf of Mexico Science|pages=45–49}}</ref> However, threats to the survival of the Gulf killifish occur because of changes in salinity.<ref name="simpson"/> Salinity has profound effects on the development and hatching of their eggs.<ref name="crego"/> One of the secondary effects of the Deepwater Horizon oil spill was the opening of industrial canals to send fresh water into the Gulf to push the oil away from the marshes of Louisiana. This caused the salinity to drop quickly within some of the fish's habitat, which caused problems that had not been expected. One of these was that many eggs remained unhatched because the salinity levels had dropped below the critical salinity level where hatching can still occur. Another study looked into how salinity affects the survival and body size of fish within different salinities.<ref name="patterson">{{cite journal|last=Patterson|first=Joshua|author2=Charlotte Bodinier |author3=Christopher Green |title=Effects of low salinity media on growth, condition, and gill ion transporter expression in juvenile Gulf killifish, ''Fundulus grandis'' |journal=Comparative Biochemistry and Physiology A|year=2012|volume=161|issue=4|pages=415–421|doi=10.1016/j.cbpa.2011.12.019|pmid=22245490}}</ref> The results from this study showed that the fish brought up in the lower salinity were less likely to survive, as well as have much lower body size and growth.<ref name="patterson"/> At 2 weeks post-hatch, Gulf killifish show reduced growth and survival in freshwater, but by 7 weeks old juvenile killifish have developed hypo-osmotic tolerance.<ref name=":0">{{Cite journal|last1=Ramee|first1=Shane|last2=Green|first2=Christopher|last3=Allen|first3=Peter J.|date=2016-01-02|title=Effects of low salinities on osmoregulation, growth, and survival of juvenile Gulf killifish|journal=North American Journal of Aquaculture|language=en|volume=78|issue=1|pages=8–19|doi=10.1080/15222055.2015.1079579 |doi-access=free|bibcode=2016NAJA...78....8R }}</ref> At 7 weeks old juvenile killifish can live in freshwater ponds without reducing their growth rate.<ref name=":0" /> Gulf killifish develop an early ability to osmoregulate because they are born with functional gills and mature mouthparts.<ref name=":0" />
===Temperatures=== The normal climate for the Gulf killifish is tropical, as would be expected from where the fish is usually found. However, the Gulf killifish is able to survive in temperatures ranging from 5 to 37 °C.<ref name="cbrown">{{cite journal|last=Brown|first=Charles A.|author2=Craig T. Gothreaux |author3=Christopher C. Green |title=Effects of temperature and salinity during incubation on hatching and yolk utilization of Gulf killifish ''Fundulus grandis'' embryos|journal=Aquaculture|year=2011|volume=315|issue=3–4|pages=335–339|doi=10.1016/j.aquaculture.2011.02.041|bibcode=2011Aquac.315..335B }}</ref> Temperature plays an important role in the hatching of viable eggs, as well as the relative abundance of these eggs.<ref name="cbrown"/> Lower water temperature with the use of shade in June, July, and August lead to the highest number and most viable eggs.<ref name="gothreaux">{{cite journal|last=Gothreaux|first=C.T.|author2=C.C. Green|title=Effects of Shading on the Reproductive Output and Embryo Viability of Gulf Killifish|journal=North American Journal of Aquaculture|year=2012|volume=74|issue=2|pages=266–272|doi=10.1080/15222055.2012.672368|bibcode=2012NAJA...74..266G }}</ref> However, in September, when the water temperature has begun to drop, the extra shading leads to much lower temperatures that lead to significantly fewer and less viable eggs.<ref name="gothreaux"/>
===Dissolved oxygen=== Another key characteristic of the habitats, which is influential to the survival of Gulf killifish, is the amount of dissolved oxygen. Fish need oxygen to survive and carry out normal activities and processes.<ref name="love">{{cite journal|last=Love|first=Joseph W.|author2=Bernard B. Rees|title=Seasonal differences in hypoxia tolerance in Gulf killifish, ''Fundulus grandis'' (Fundulidae)|journal=Environmental Biology of Fishes|year=2001|volume=63|issue=1|pages=103–115|doi=10.1023/a:1013834803665 |s2cid=33280697 }}</ref> Lower levels of oxygen is common in near-shore environments, one of the main habitats of the Gulf killifish.<ref name="tyson">{{cite journal|last=Tyson|first=R.V.|author2=T.H. Pearson|title=Modern and ancient continental shelf anoxia: an overview|journal= Geological Society, London, Special Publications|year=1991|doi=10.1144/gsl.sp.1991.058.01.01|volume=58|issue=1|pages=1–24|bibcode=1991GSLSP..58....1T|s2cid=140633845 }}</ref> These conditions may last from several hours to several days.<ref name="malone">{{cite journal|last=Malone|first=T.C. |author2=L.H. Crocker |author3=S.E. Pike |author4=B.W. Wendler|title=Influences of river flow on the dynamics of phytoplankton production in a partially stratified estuary|journal=Marine Ecology Progress Series|year=1988|volume=48|pages=235–249|doi=10.3354/meps048235|bibcode=1988MEPS...48..235M |doi-access=free}}</ref> Gulf killifish use different ways to cope with low oxygen conditions, including behavioral changes, physiological changes, and changes to biochemical processes.<ref name="love"/> One main threat because it decreases the levels of dissolved oxygen is the Louisiana dead zone, which kills large numbers of fish every year.<ref name="tyson"/> This dead zone results from nutrient- and chemical-rich water from the Mississippi River Valley basin entering the Gulf of Mexico. This eutrophic water ultimately leads to no dissolved oxygen remaining within the ecosystem because of increased activities of algae and decomposers.<ref name="malone"/> Fish unable to leave the dead zone in time will die because of the lack of oxygen.<ref name="tyson"/> Fish collected during the summer were better suited to hypoxic conditions because they were already acclimated to the lower levels of dissolved oxygen more so then than any other season.<ref name="love"/> Due to the higher temperatures during the summer, less dissolved oxygen is available within the ecosystem.<ref name="love"/>
==Toxicology== ===Gulf killifish larvae=== ''F. grandis'' is an egg-laying fish, and uses the soft muddy bottoms of saltwater or brackish ecosystems to lay eggs. They are known as an "annual" fish because their lifecycle, from birth to mating and ultimately death usually does not exceed one year.<ref>{{cite encyclopedia|title=Killifish|url=http://www.britannica.com/EBchecked/topic/317779/killifish|encyclopedia=Encyclopædia Britannica|access-date=21 October 2012}}</ref> One adaptation that has allowed ''F. grandis'' to survive so efficiently is the versatile nature of their eggs. The eggs not only protect the developing embryo, but also prevents them from drying out and hindering the development of the inlaid fish. The egg's shell is sensitive to dissolved oxygen and carbon dioxide present within the water that can initiate hatching.<ref>{{cite web|last=Lepley|first=Max|title=Killifish Lifecycle|url=http://infolific.com/pets/fish-in-the-wild/killifish-life-cycle/|publisher=Infolific|access-date=22 October 2012}}</ref> This internal form of evolution is compromised when anthropomorphic effects disrupt the aquatic ecology in which they are laid.{{Cn|date=April 2021}}
Such biochemical effects may result from the presence of oil or oil dispersants in the water in which the fish lay their eggs. Time of exposure and the weather conditions present when the eggs are laid also play a definitive role in how these eggs and larvae can be affected.<ref>{{cite web |author=Thomas |author2=Bonner |author3=Whiteside |title=Gulf Killifish Fundulus Grandis|url=http://www.bio.txstate.edu/~tbonner/txfishes/fundulus%20grandis.htm|access-date=22 October 2012 |archive-url=https://web.archive.org/web/20080808112447/http://www.bio.txstate.edu/~tbonner/txfishes/fundulus%20grandis.htm |archive-date=2008-08-08}}</ref> Oil or oil dispersants can become a hazard for larval ''F. grandis'' when they percolate down into the sediment where the eggs are laid. These substances can then begin to affect the biochemical morphology of the developing embryos or newly hatched larvae, leading to underdeveloped cardiovascular systems, decreased nerve functions, decreased endocrine and hormone secretions, and reduced gill tissue development.<ref>{{cite journal|vauthors=Dubansky B, Bodinier C, Rice CD, Whitehead A, Galvez F |title=Effects of exposure to crude oil from the Deepwater Horizon Oil Spill on populations of Gulf killifish (''Fundulus grandis'') in Barataria Bay, Louisiana|journal=Integrative and Comparative Biology|volume=52|issue= Suppl 1|doi=10.1093/icb/ics078|pages=e1–e201|doi-access=free|hdl=10211.3/169102|hdl-access=free}}<!--|access-date=22 October 2012--></ref>
===Gulf killifish adults=== ''F. grandis'' reaches adulthood as early as three to four months old, but on average close to 1 year of age. It may grow to about 6–7 in long when fully grown. Females may also grow 5–8 cm larger than the males and may exhibit more aggressive behaviors during the mating season. Once fully grown, ''F. grandis'' adults are omnivorous, feeding on algae and vascular plants, small grass shrimps (''Palaemonetes''), microcrustaceans (copepods), and mosquito larvae.<ref name="simpson"/> Adults feed mainly on mosquito larvae and pupae, which has helped to reduce the mosquito population in marsh and wetland areas. ''F. grandis'' also serves as one of the most popular bait minnows for commercial and recreational fishing.<ref>{{cite journal |author1=Harrington, R. W. Jr |author2=E. S. Harrington |title=Food selection among fishes invading a high subtropical salt marsh: from onset of flooding through the progress of a mosquito brood|journal=Ecology|year=1961|volume=42|issue=4|pages=646–666|doi=10.2307/1933496|jstor=1933496 |bibcode=1961Ecol...42..646H }}<!--|access-date=22 October 2012--></ref>
===Gulf killifish evolution to toxic environments=== ''F. grandis'' populations in the highly polluted waters of the Houston Ship Channel were recently found to have adapted to resist the effects of the pollution.<ref name="Oziolor et al. 2014">{{cite journal|author1=Oziolor, E. M. |author2=Bigorgne, E. |author3=Aguilar L. |author4=Usenko, S. |author5=Matson, C. W.|title=Evolved resistance to PCB- and PAH-induced cardiac teratogenesis, and reduced CYP1A activity in Gulf killifish (''Fundulus grandis'') populations from the Houston Ship Channel, Texas|journal=Aquatic Toxicology|volume=150 |year=2014|issue=250|pages=210–219|doi=10.1016/j.aquatox.2014.03.012 |pmid=24699180 |bibcode=2014AqTox.150..210O }}</ref> This resistance confers protection to embryos of these populations from cardiac teratogenesis (developmental deformities in the heart) compared to embryos from reference and un-contaminated populations.<ref name="Oziolor et al. 2014"/> Further, the adapted populations of Gulf killifish seem to also be more resistant to pesticides, oxidative stress, and have a higher metabolism, which could be stemming from the strong selection that these organisms have been under to develop resistance to strong contamination.<ref>{{cite journal|author1=Oziolor, E. M.|author2=Dubansky, B.|author3=Burggren, W. W.|author4=Matson, C. W.|title=Cross-resistance in Gulf killifish (''Fundulus grandis'') populations resistant to dioxin-like compounds|journal=Aquatic Toxicology|volume=175|year=2016|issue=175|pages=222–231|doi=10.1016/j.aquatox.2016.03.019|pmid=27064400|bibcode=2016AqTox.175..222O }}</ref> This strong resistance and cross-resistance suggests the role of adaptation to anthropogenic contaminants in this environment. Such events are widespread in many fish species and populations.{{Cn|date=April 2021}}
==Deepwater Horizon oil spill== The Gulf killifish plays an important role in scientific research concerning the disaster resulting from the Deepwater Horizon oil spill. The spill occurred in April 2010 and resulted in an estimated 53,000 barrels per day of Macondo-252 crude oil being spilled from the well before it was capped in September 2010.<ref>{{cite news|last1=Robertson |first1=Campbell |last2=Krauss |first2=Clifford |url=https://www.nytimes.com/2010/08/03/us/03spill.html |title=Gulf Spill Is the Largest of Its Kind, Scientists Say|newspaper=The New York Times|access-date=5 May 2019|date=2 August 2010 }}</ref> The spill affected the Gulf coast area about a year and was finally determined to be maintained in October 2011. Several coastal reconstruction projects are still underway to try to restore the ecosystems of the Gulf.<ref>{{cite web|title=Restore The Gulf|url=http://www.restorethegulf.gov/|access-date=23 October 2012}}</ref>
===Macondo-252 crude oil=== <!-- The prospect oil drilled from the BP offshore well in the Gulf of Mexico. This is the name of the field of the Deepwater Horizon oil spill, and is the primary oil studied on ''F. grandis'' to determine its effects on marine life. The oil is composed of several hydrocarbons that make up its chemical structure.<ref>{{cite web|last=Dittrick|first=Patricia|title=BP: Macondo sheen likely coming from oil droplets on cofferdam|url=http://www.ogj.com/articles/2012/10/bp-macondo-sheen-likely-coming-from-oil-droplets-on-cofferdam.html|work=Oil and Gas Journal|access-date=24 October 2012}}</ref> -->
The response of ''F. grandis'' fish to Macondo-252 crude oil depends mostly upon the stage in their lifecycle and their exposure time. Once spilled into water, this oil floats on the surface and affects ''F. grandis'' populations. The oil has the ability to harm fish species by different means. Floating oil can come into contact with the Gulf killifish by simply drifting into them, or the fish swimming through the oil trying to reach the surface. During the Deepwater Horizon spill, the Macondo-252 oil slick was composed of over 205 million gallons of crude oil.<ref>{{cite journal|last=Guarino|first=Mark|title=Mystery in Gulf of Mexico: Why is oil leaking from Deepwater disaster site?|url=https://www.csmonitor.com/Environment/2012/1019/Mystery-in-Gulf-of-Mexico-Why-is-oil-leaking-from-Deepwater-disaster-site|journal=The Christian Science Monitor|access-date=24 October 2012|date=19 October 2012}}</ref> The floating oil affected the fish's health by being absorbed through the gills and getting into the eyes of the fish that came into contact with the oil. This imposed several physiological strains on them.<ref name="Gaskill">{{cite journal|last=Gaskill|first=Melissa|title=Trace amounts of crude oil harm fish|url=http://www.nature.com/news/2011/110926/full/news.2011.546.html|journal=Nature|doi=10.1038/news.2011.546|year=2011|doi-access=free|url-access=subscription}}</ref><ref name="Whitty 2011">{{cite journal|last=Whitty|first=Julia|title=Gulf Fish Hammered by BP Oil|journal=Mother Jones|date=1 September 2011|url=https://www.motherjones.com/blue-marble/2011/09/gulf-fish-hammered-bp-oil|access-date=22 October 2012}}</ref>
Macondo-252 oil may also drop within the water column and pose a new ecological threat, due to the oil percolating into the sedimentary layer under the water. The direct impacts are to the egg development and larval stage of the Gulf killifish. Oil in the sedimentary layer can be transferred through endocytosis-like processes that bring the developing ''F. grandis'' embryos into direct contact with the oil.<ref>{{cite web |last=eHow Contributo |title=How Do Oil Spills Affect Fish? |work=Environmental Factors |url=http://www.how.com/howdoes_5489780_do-oil-spills-affect-fish.html |access-date=7 November 2012 }}</ref>
===Corexit 9500=== The toxicology of the oil dispersant Corexit 9500 on ''F. grandis'' has been studied. Corexit 9500 is produced and distributed through NALCO and is a hazy, amber-colored liquid that acts to break down the oil.<ref>{{cite web|title=Product Safety Department|url=http://www.lmrk.org/corexit_9500_uscueg.539287.pdf|work=Corexit 9500|publisher=Nalco. N. P.|access-date=22 October 2012|archive-url=https://web.archive.org/web/20120915020023/http://lmrk.org/corexit_9500_uscueg.539287.pdf|archive-date=15 September 2012}}</ref> Corexit 9500 is sprayed by airplanes on floating oil slicks to cause the floating oil to sink to the bottom of the water in which it is suspended. Corexit 9500 was the primary oil dispersant used in the Deepwater Horizon oil spill in the Gulf, and impacted several of the Gulf coast aquatic ecosystems. The dispersant has been shown to affect biochemical pathways of some marine species, such as the Gulf killifish.<ref>{{cite journal |author=Charles A. Brown |author2=Fernando Galvez |author3=Christopher C. Green |title=Embryonic developments and metabolic costs in the Gulf killifish ''Fundulus grandis'' exposed to varying environmental salinities |journal=Fish Physiology and Biochemistry |volume=38 |issue=4 |doi=10.1007/s10695-011-9591-z |pmid=22252334 |pages=1071–1082|year=2012 |s2cid=254515195 }}</ref>
==See also== * Barataria Bay * Macondo Prospect
==References== {{Reflist|25em}} * [http://www.protecttheocean.com/gulf-oil-spill-bp/ Protecttheocean.com: BP Gulf of Mexico oil spill]
{{Taxonbar|from=Q2751094}}
Gulf killifish Category:Fish of the Gulf of Mexico Category:Fish of Cuba Category:Fish of the Dominican Republic Category:Fauna of the Southeastern United States Gulf killifish Category:Taxa named by Spencer Fullerton Baird Category:Taxa named by Charles Frédéric Girard