(DRAFT) - Taxonomy
Species mummichog
Species Id M010077
Date 26 AUG 96
TAXONOMY
NAME - mummichog
OTHER COMMON NAMES - mud minnow, pike minnow, mud dabber, gudgeon, saltwater minnow, killie, mummie, marsh minnow, Common Killifish and Brackish Water Minnow
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - Chordata,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Atheriniformes,
FAMILY AND SUBFAMILY - Cyprinodontidae,
GENUS AND SUBGENUS - Fundulus,
SPECIES AND SSP - heteroclitus,
SCIENTIFIC NAME - Fundulus heteroclitus
AUTHORITY - Robins et al., 1980
TAXONOMY REFERENCES - 56
COMMENTS ON TAXONOMY -
Other common names include: mud minnow, pike minnow, mud dabbler, gudgeon,
saltwater minnow, killie, mummie, marsh minnow, common killifish, brackish
water chub.*56*
Taxonomy - 1 (DRAFT) - Status
Species mummichog
Species Id M010077
Date 26 AUG 96
STATUS
Coded Status
Commercial/bait
See Comments
REFERENCES FOR STATUS - 56
COMMENTS ON STATUS -
Although not valued as commercial or sport fishes, killifish are important
in food chains because of their distribution and abundance. Because of
their importance in marsh food chains, mummichogs may be instrumental in
movement of organic material within and out of salt marsh ecosystems (Kneib
et al. 1980).
Mummichogs are the primary predators in the Open Marsh Water Management
mosquito control program currently being tested in New Jersey, Delaware, and
Maryland (Winner et al. in press). Although Gambusia (mosquitofish, Family
Poeciliidae) is more often used as a biological control agent, the portion
of the diet consisting of mosquito larvae is higher in studied species of
Fundulus. According to Harrington and Harrington (1961), the role of
Gambusia affinis against Aedes mosquitoes has been overvalued because of
its reputation as a predator on freshwater anophelines; in the control of
saltmarsh mostquitoes, primary consideration should be given to the local
endemic cyprinodontiform fishes rather than any single species.
As a group, killifishes are used in research in experimental studies of
embryology, genetics, physiology, endocrinology, cytology, and behavior.
Some of this research has important medical implications, such as the action
of steroids in the regulation and reversal of sexual development,
inheritance and development of cancerous tissues, and the genetics of
histocompatability in tissue and organ transplants (Rosen 1973). Mummichogs
are the nondomesticated fish most frequently used in research (Rosen 1973),
including such disparate studies as bioassay for water pollution (Isai et al
1979), effects of weightlessness in outer space (Hoffman et al. 1978), ion
transport in tissues (Evans 1980), and cycling and biological magnification
of radioisotopes (Huver 1973).*56*
Status - 1 (DRAFT) - Distribution
Species mummichog
Species Id M010077
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - TIDAL CREEK
REFERENCES FOR HABITAT - 56
REFERENCES FOR SPECIES ASSOCIATIONS - 56
COMMENTS ON SPECIES ASSOCIATIONS -
Predators
Small tidal marsh fishes, such as killifishes, are the major prey for
wading birds, aerial searching birds, piscivorous ducks, and many predatory
fishes (Peterson and Peterson 1979). These predators include herons,
egrets, terns, gulls, striped bass, and bluefish (Valiela et al. 1977). The
diet of nesting herons and egrets may contain up to 30% Fundulus spp. (Jenni
1969). Least and common terns eat Fundulus spp. in pools when the tide goes
out (Butner and Brattstrom 1960). Selective predation by visual predators
is suggested by increased mortality in male mummichogs after they achieve
sex-specific coloration (Kneib and Stiven 1978).
From late August to early September in Delaware, American eels (Anguilla
rostrata) preyed heavily on mummichogs (Lotrich 1975). Other fish that prey
on Fundulus spp are white perch (Morone americana: Miller 1963), summer
flounder (Paralichthys dentatus: Meredith and Lotrich 1979), and red drum
(Sciaenops ocellata: Peterson and Peterson 1979). Fundulus spp. are also
eaten by crabs (Libinia, Callinectes, Uca: Butner and Brattstrom 1960;
Eurytium limosum: Kneib in press). Predation by blue crabs produces
size-specific losses in experimental field populations of mummichogs (Kneib
1982). Another example of size-specific predation is cannibalism of their
own eggs by spawning mummichogs (Able and Castagna 1975).*56*
Habitat Associations - 1 (DRAFT) - Food Habits
Species mummichog
Species Id M010077
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
OMNIVORE
REFERENCES FOR TROPHIC LEVEL - 56
LIFESTAGE FOOD FOOD PART
General Algae Not Specified
General Polychaetes Not Specified
General Bivalve Molluscs Not Specified
General Crustaceans Not Specified
General Ostracods Not Specified
General Copepods Not Specified
Important Diptera Larva stage
General Hymenoptera Larva stage
General Fish Egg/Fetus stage
REFERENCES FOR GENERAL FOOD - 56
REFERENCES FOR IMPORTANT FOOD - 56
COMMENTS ON FOOD -
Feeding Behavior/Food Habits
The protruding lower jaw and tilted mouth of cyprinodontids are
well-adapted to surface feeding (Eddy 1957). Fundulus, however, does not
hesitate to feed in mid-water or on the bottom (Huver 1973). Grass shrimp
(Palaemonetes pugio) swimming near the surface are often consumed, perhaps
because they are silhouetted against the light (Heck and Thoman 1981).
Vision plays an important role in feeding of mummichogs, but swallowing
depends upon another sense, probably olfactory (Hara 1971).
Mummichogs use all potential food sources: organisms in the water column,
subtidal benthos (Weisberg and Lotrich 1982). Recent radioisotope tracer
studies have shown that 56% of mummichogs' body carbon is derived from algal
(benthic and planktonic) food chains and 44% from the Spartina food chain
(Hughes and Sherr 1983).
Baker-Dittus (1978) decided that Fundulus uses all available food items
except detritus. She found small crustaceans and polychaetes to be the most
frequent food of mummichogs. Fritz (1974) ranked food items found in the
guts of mummichogs 22-101 mm long. Copepods were the most common, followed
in order by flies (mostly larvae and pupae), amphipods, polychaetes (mostly
Nereis virens), isopods, ostracods, snails, insects, bivalves, algae,
fishes, fish eggs, beetles and shrimps, and hymenopterans. In one North
Carolina marsh, the major prey of mummichogs were fiddler crabs,
polychaetes, tanaids, and other small curstaceans. Fish less than 30 mm SL
primarily ate small crustaceans (amphipods, tanaids, copepods); larger fish
consumed crabs, detritus, and algae more often (Kneib and Stiven 1978; Kneib
et al. 1980). Although mummichogs may ingest large quantities of detritus
while feeding on the surface of the substrate, detritus is not a significant
energy source for them because it is not assimilated (Prinslow et al. 1974).
Mummichogs cannot subsist on a diet of plant material or detritus (Katz
Food Habits - 1 (DRAFT) - Food Habits
Species mummichog
Species Id M010077
Date 26 AUG 96
1975).
Mummichogs swallow their prey intact, so mouth gape limits prey size.
Large mummichogs will also eat small prey, but larger prey are more
important in their diet (Vince et al. 1976). The numerical response of most
infaunal invertebrates to mummichog predation depends on fish size more than
fish density. Kneib and Stiven (1982) attributed this to very small infauna
(organisms in bottom sediments) not being readily available to larger fish.
Mummichog populations are large enough to influence their prey's
distribution and abundance (Valiela et al. 1977), but few studies have
convincingly demonstrated this result (Kneib 1984). Some prey species that
may be regulated by mummichogs are the amphipod Gammarus palustris (Van
Dolah 1978), the pulmonate snail Melampus bidentatus (Vince et al. 1976),
and the soft-shelled clam Mya arenaria (Kelso 1979). Kneib (in press)
points out that, by controlling smaller predators, mummichogs may indirectly
increase densities of some infaunal marsh invertebrates. Also, predation by
larval and juvenile mummichogs, which has previously been overlooked, may
affect the patchy distribution patterns of some small invertebrates (e.g.,
harpacticoid copepods) in salt marshes.*56*
Food Habits - 2 (DRAFT) - Environment Associations
Species mummichog
Species Id M010077
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Water Temperature: Specified in Comments
E Water Temperature: Between 15-21 degrees C
G
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 56
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Temperature
Temperate marine fishes do not normally survive water temperatures
greater than 34 degrees C (de Silva 1969). However, several species of
Fundulus can recover from exposures to 40-42 degrees C water (Altman and
Dittmer 1966).
Mummichogs are eurythermal (de Silva 1969). In Delaware salt marshes,
mummichogs experience a temperature fluctuation of 6-35 degrees C (Schmeltz
1964). In Maine salt marshes, summer tidal cycles expose mummichogs to
rapid temperature changes from 15 to 30 degrees C. Swimming ability is
maintained in nature during temperature fluctuations which would
substantially impair contractile function in other fishes.*56*
COMMENTS ON FEEDING ADULT ENVIRONTAL ASSOC_ -
Although assimilation (digestion) efficiency of mummichogs varies
significantly with temperature in the laboratory, this is probably of
little ecological significance. Maximum efficiency occured from 13 to 29
degrees C in the laboratory; at lower temperatures fish simply took longer
to digest their food (Targett 1979).*56*
Although mummichogs are physiologically euryhaline, Fritz and Garside
(1974) considered salinity preference to be the most important enviromental
factor influencing their distribution in Nova Scotia. Mummichogs are
especially tolerant of abrupt salinity changes. They adapt so quickly that
prior salinity acclimation has no effect on laboratory testing of reponse
to salinity (Garside and Chin-Yuen-Kee 1972).*56*
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Mummichogs spawn in water from 16.5 to 25 degrees C (Hardy 1978).*56*
COMMENTS ON FEEDING LARVAE ENVIRONMENTAL ASSOC_ -
Mummichog larvae survive in water between 0.39 ppt (fresh, by definition)
and 10 ppt, although growth is retarded at salinities greater than that of
seawater (32-33 ppt). Larvae are active and feed in water under 1 ppt, but
Environment Associations - 1 (DRAFT) - Environment Associations
Species mummichog
Species Id M010077
Date 26 AUG 96
do not survive more than 11 days in tap water (Joseph and Saksena 1966).
When mummichog embryos are incubated in salinities of <0.5 ppt to 60 ppt,
those in 20 ppt are always the longest and those in freshwater are always
the shortest (Tay and Garside 1978).*56*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Eggs develop at temperatures of 12-27 degrees C with less than a 2%
increase of abnormality (Smith 1982). The median time to hatching is
inversely related to water temperature (Tay and Garside 1975). Although
hatching is not affected by the normally encountered range of temperatures,
the hatching enzyme is unstable at 30 degrees C or above (DiMichele et al.
1981).*56*
Low dissolved oxygen is a necessary hatching stimulus for mummichog effs
(DiMichele and Taylor 1980).
The ability of ova from northern and southern populations of mummichogs
to be fertilized at various salinities was examined by Bush and Weis(1983).
There was no difference in the ability of sperm to fertilize ova at 30 ppt.
However, at 15 ppt there was a difference, which may mean that egg response
to salinity varies geographically.
Environment Associations - 2 (DRAFT) - Life History
Species mummichog
Species Id M010077
Date 26 AUG 96
LIFE HISTORY
Morphology/Identification Aids
The snout is short, rounded, a little longer than diameter of eye in side
view, with 8 mandibular pores. A well-developed fleshy pouch is found at
the anterior base of the anal fin. Scales along the lateral line number
31-35 (Rosen 1973, but Hardy 1978 gives 31-39). There are 11-12 dorsal fin
rays (Hildebrand and Schroeder 1928). There is no conspicuous silvery sheen
on the sides; adult females have no dark spot on dorsal fin (Rosen 1973),
and are brownish-green above, paler below. Small females have 13-15 dark
vertical bars (Hildebrand and Schroeder 1928); adult females may be confused
with those of F. confluentis (Rosen 1973). Adult males are dark green or
olive above, yellow beneath; have sides with about 15 narrow silvery
vertical bars and numerous white or yellowish spots; and have a dark spot on
posterior 4-5 rays of dorsal fin. Sex-specific color patterns appear when
fish are 38-44 mm long (Hildebrand and Schroeder 1928); until then, young
may be confused with adult female F. luciae (Rosen 1973). Adults are
commonly 51-102 mm long (Armstrong and Child 1965). The largest specimen
reported from Chesapeake Bay was 125 mm (Hildebrand and Schroeder 1928).*56*
Reproductive Physiology
During the breeding season, males of mummichogs and striped killifish
assume a brigher coloration (Ursin 1977) and grow contact organs (Hardy
1978). Fundulus spp are oviparous. The ovary is single, and the number of
ova produced depends upon the size of the fish. The largest number of ripe
ova in a mummichog from Chesapeake Bay counted by Hildebrand and Schroeder
(1928) was 460, in a female 98 mm long; the maximum for a striped killifish
was 540 (length not given). Hardy (1978) gave a range of 200-800 ova for
mummichogs and 460-800 for striped killifish in the Mid-Atlantic region.
According to Taylor (in press), production of 100-300 eggs per day for 3-5
days is not unusual for Delaware mummichogs early in the spawning season.
However, even early in the spawning season in North Carolina, up to 50% of
the ova may be reabsorbed (Kneib and Stiven 1978).
Spawning Season and Periodicity
Spawning of mummichogs usually begins in spring (March to May) and ends in
later summer or early autumn (July to September)(Hardy 1978; Kneib, in
press). Although timing and duration of spawning seasons differ, the water
temperature range over which spawning occurs is similar (Taylor, in press).
Mummichogs may spawn eight or more times in a season. Each spawning peak
may last five or more days and coincides with a high spring tide of the full
or new moon (semilunar periodicity: Taylor and DiMichele 1980). A
circadian periodicity may be superimposed on the semilunar rhythm in some
populations; maximal spawning then occurs when high spring tides are at
night (Taylor et al. 1979). Spawning also occurs during the day (Hardy
1978).
Spawning in separate genetic populations of mummichogs may be timed by
different environmental stimuli (Wallace and Selman 1981). Spawning rhythms
may be timed by temperature (Brummett 1966), tides, moonlight, and salinity
(Taylor et al. 1979). Early and late season peaks in spawning, such as
Kneib and Stiven (1978) observed in mummichogs, may be caused by a
combination of moderate temperatures and shorter daylengths (Harrington
1959). Day and Taylor (1983) found that a photoreceptor other than the
Life History - 1 (DRAFT) - Life History
Species mummichog
Species Id M010077
Date 26 AUG 96
pineal gland or retina of the eye influences seasonal reproduction in
mummichogs. Female mummichogs respond to photoperiod, buts its
effectiveness has not been rigorously tested in males (Taylor, in press).
In both sexes, low temperature prevents and high temperature permits gonadal
development (Taylor, in press). The semilunar cycle of oogenesis persists
in the absence of lunar or tidal stimuli (Taylor and Dimichele 1980).
Schwassmann (1980) argued that we have no idea of the actual timing
mechanism that entrains semilunar spawning in mummichogs.*56*
Eggs
Fertilized eggs of mummichogs are spherical, about 2 mm in diameter
(range: 1.5-2.5 mm), and transparent yellow to amber (Hardy 1978); dead or
infertile eggs are opaque (Taylor, in press). Adhesive chorionic fibrils on
eggs may be long and dense, short and sparse, or absent in various
populations (Hardy 1978; Morin and Able 1983). These fibrils may anchor
eggs to the substrate and/or retain moisture when eggs are stranded
(Brummett and DuMont 1981).
Mummichog eggs normally incubate in air and are not submerged until the
next spring tide after they are laid (Taylor and DiMichele 1980). Eggs fail
to develop if immersed for extended periods in water with less than 1 ml/l
dissolved oxygen (DO) (Taylor, in press). Incubation of mummichog eggs in
the field takes 7-8 days at 22-34 degrees C. (Taylor et al. 1977); in the
laboratory at 20 degrees C, hatching occurs in 10.5 days (Armstrong and
Child 1965).
Yolk-Sac Larvae
The yolk-sac larval stage lasts from hatching until all yolk is absorbed,
and may also be called the prolarva, free embryo (Chuganova 1963), or alevin
(Tay and Garside 1978). Larvae of mummichogs may hatch with
the yolk already absorbed, if immersion of developed eggs has been
delayed (Taylor et al. 1977). At hatching mummichog embryos are 4.0-7.7 mm
(mean 5.0 mm) long; striped killifish are 7.0-11.0 mm long (Hardy 1978). In
the laboratory at 20 degrees C newly hatched mummichogs require 5.5 days to
absorb the yolk. As the yolk disappears, dorsal and ventral fins form, and
the coordination of the lower jaw and operculum, undulating swimming, and
pectoral fin movements are perfected (Armstrong and Child 1965).
Larvae
The larval stage lasts from yolk-sac absorbtion until the fish attains the
characteristic shape of the species. During this stage the fin rays and
scales develop (Chuganova 1963). Striped killifish larvae are 11.8-23.8 mm
long. In mummichogs scales first appear above the pectoral fin at about
12.5 mm, and are well developed at 20.0 mm (Hardy 1978).
Juveniles
Juveniles are also called fry or young-of-the-year, and have fully
developed fins and a more or less distinct scale covering (Chuganova 1963).
The minimum described length of this stage in mummichogs is 25.0 mm (Hardy
1978). For a detailed description of this stage for both species, see Hardy
(1978).
Adults
Females mummichogs are sexually mature at 38 mm and males at 32 mm;
Life History - 2 (DRAFT) - Life History
Species mummichog
Species Id M010077
Date 26 AUG 96
striped killifish females mature at 76 mm and males at 64 mm (Hildebrand and
Schroeder 1928). Most members of both species attain maturity during their
second year, although some mummichogs may mature and spawn during their
first year (Hardy 1978; Kneib and Stiven 1978).*56*
REFERENCES FOR LIFE HISTORY- 56
Life History - 3 (DRAFT) - Management Practices
Species mummichog
Species Id M010077
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Maintaining unique or special habitat features [wetlands, caves,
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 56
Management Practices - 1 (DRAFT) - References
Species mummichog
Species Id M010077
Date 26 AUG 96
References
56* Abraham, B. 1985. Species Profiles: Life Histories and
Environmental Requirements of Coastal Fishes and Invertebrates
(Mid-Atlantic)--Mummichog and Striped Killifish. U.S. Fish and
Wildlife Service Biol. Rep. 82(11.40) pp 23.
References - 1