|
Potentially Misidentified Species:
Identification of amphipods to the species level is generally beyond the
abilities of amateur naturalists. The large eyes and phytal
(plant-associated), tube-dwelling habits of this species are useful aids in
identification.
II. HABITAT AND DISTRIBUTION
Regional Occurrence:
Cymadusa compta is widely distributed along the Atlantic and Gulf
coasts of the United States, ranging from the Gulf of Maine and Cape Cod
south to Florida and west along the Gulf of Mexico to Texas (Bousfield
1973, Morgan and Kitting 1984, Hauxwell et al. 1998).
IRL Distribution:
Cymadusa compta is widespread throughout the seagrass habitats of the IRL system (Stoner 1983).
III. LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Females are typically 12-15 mm in length and males are somewhat smaller,
7-11 mm (Bousfield 1973), although animals up to 20 mm have been reported
(Hauxwell et al. 1998). Cymadusa compta is an annual species.
Abundance:
Marsh (1973) notes that Cymadusa compta ranked 9th in abundance of
mcroinvrtebrates in a study he conducted in the York River Estuary, VA, and
was one of only 6 species present in all 48 samples collected in that
study. Fox and Bynum (1975) list C. compta as a common and
widespread component of North Carolina estuarine systems. Stoner at al.
(1983) report a density of around 200 individuals per square meter in
Pensacola Bay grassbeds, while Sheridan and Livingston (1983) indicate a
seasonal numerical dominance for the species in Apalachicola Bay occurring
from October to February and reaching a peak abundance of more than 4,300
individuals per square meter.
Nelson et al. (1982) report that C. compta was the dominant
seagrass-associated amphipod in all four sampling sites examined by the
author within the Indian River portion of the IRL complex. These authors
note that C. compta is actually more abundant in the IRL than the
ubiquitous seagrass amphipod Gammarus mucronatus, but is not as
motile or as conspicuous.
Reproduction:
Cymadusa compta reproduces sexually and the sexes are separate.
Bousfield (1973) indicates ovigerous females are present in New England
waters from May-September, but the reproductive season is likely to be
longer and possibly year-round in the southern portion of the species
range.
Females become ovigerous at approximately 2 weeks old. Clutch size varied
from less than 5 eggs/individual to around 25 eggs/ individual and varied
with diets of different nutritional value in laboratory experiments
(Cruz-Rivera and Hay 2000).
Embryology:
Limited information on embryology is available. The eggs are contained by
the female within a thoracic brood pouch and young hatch out as fully
developed juveniles with no free-living larval stage.
IV. PHYSICAL TOLERANCES
Temperature:
The broad distribution of this amphipod from the Gulf of Maine and Cape Cod
southward into Florida indicates the species is eurythermal in its
temperature tolerance.
Salinity:
Boesch and Diaz (1974) list Cymadusa compta as mesohaline to
polyhaline in its salinity tolerance, and provides a range of 5-30 ppt
corresponding with that designation. Examination of NOAA NBI collection records
reveals the species has been collected collected at higher salinities of
nearly 44 ppt.
Feeley (1967) describes seasonal migrations of C. compta and also
the amphipod Ampithoe longimana in response to salinity fluctuations
in the Chesapeake estuary.
V. COMMUNITY ECOLOGY
Trophic Mode:
Cymadusa compta is primarily an epiphyte and macroalgal grazer and
detritivore (Luczkovich et al. 2002). Grazing studies by Zimmerman et al.
(1979) reveal that C. compta consumed macroepiphytic algae, drift algae,
and seagrass detritus, and consumes macroalgae at a higher rate than
epiphytes when both are abundant Although it readily shreds phytodetritus,
C. compta appears to feed very little on live seagrass (Kelly et al
1990). However, gut content analysis has revealed some vascular plant
material (Nelson 1979). Chemically defended seaweeds are actively avoided
(Cruz-Rivera and Hay 2003).
Competitors:
Significantly positive association of Cymadusa compta and
Gammarus mucronatus in habitats they share is likely due to the very
similar diets of these species (Zimmerman et al. 1979, Rey and Stoner
1984). Detrital material is typically abundant in these habitats, so
competition based on limiting food resources might not be expected to
occur. An earlier study by Cory (1967), however, makes a case for
competition between C. compta and the amphipod Ampithoe
longimana in the Patuxent River Estuary, MD. The author notes that
where these species co-occur they settled on experimental plates such that
all C. compta individuals were located on one side of the panel and
all A. longimana confined themselves to the opposite side. Cory suggests
this is cogent evidence of territorialism on a microscale.
The ability of this species to construct tube homes on plant
surfaces is likely to minimize space competition with both tube-building
and non tube-building heterospecifics.
Predators:
Cymadusa compta and other seagrass-associate amphipods are important
links in estuary food webs. In the IRL, they are of particular importance
to young-of-the-year pinfish (Lagodon rhomboids) and other juvenile
fish species (Stoner 1979, 1983 Nelson 1995). It is also a potential prey
species for macroinvertebrates such as the nemertean worm Tetrastemma
elegans (McDermott 1976).
C. compta and other amphipods have been observed to preferentially
occupy dense seagrass patches over sparse ones, presumably as a way to
minimize predation risk (Stoner 1979, 1980).
Parasites:
Cymadusa compta and other seagrass-associate amphipods are important
links in estuary food webs. In the IRL, they are of particular importance
to young-of-the-year pinfish (Lagodon rhomboids) and other juvenile
fish species (Stoner 1979, 1983 Nelson 1995). It is also a potential prey
species for macroinvertebrates such as the nemertean worm Tetrastemma
elegans (McDermott 1976).
C. compta and other amphipods have been observed to preferentially
occupy dense seagrass patches over sparse ones, presumably as a way to
minimize predation risk (Stoner 1979, 1980).
Habitats:
Cymadusa compta is a sedentary tube/nest-dwelling species (Marsh
1973). It has been collected from a number of IRL habitat types, including
seagrass beds, macroalgae, and sand and mud bottoms. Zimmerman et al.
(1979) indicate a habitat preference for Halodule beaudettei
(=wrightii), while Stoner (1983) reports the highest densities in the
Indian River Lagoon in, respectively, Thalassia, Syringodium,
and Halodule. On a per biomass basis, experimental animals prefer
Halodule over Thalassia and Syringodium, but when
seagrass was offered at equivalent surface areas no preference is observed
(Stoner 1980).
Rey and Stoner (1984) also found C. compta on nearly 50% of the sea
hare (Aplysia brasiliana) egg masses the examined, and noted that it
was one of three species that together accounted for greater than 90% of
the individuals collected from egg masses.
Although primarily a benthic associate, Williams and Bynum (1972) report
that C. compta was routinely collected as part of the meroplankton
in estuarine surface plankton tows in North Carolina. Nelson and
Demetriades (1992) note that C. compta is a very rare component of
the peracarid community associated with Sabellariid (Phragmatopoma
lapidosa) worm rock.
Individuals build mucus tubes on the plants they inhabit which limits to a
degree their foraging range and mobility (Cruz-Rivera and Hay 2000).
Colinization studies using artificial seagrass plots reveal C.
compta is a mobile species capable of colonizing available habitat even
though it is a tube-dweller (Bartholomew 2002).
Unlike some other gammaridean amphipods (e.g., Melita elongata),
C. compta does not aggregate gregariously, and is more cryptic in
appearance as well as behavior (Stoner 1980).
Activity Time:
Williams and Bynum (1972) collected moderate numbers of water column
Cymadusa compta in nighttime surface plankton tows and also
collected more individuals during full moons compared to new moons,
indicating a degree of nocturnal activity as well as lunar periocicity in
terms of behavior.
VI. SPECIAL STATUS
Special Status:
None.
Economic Importance:
Fredette et al. (1990) estimate the contribution of Cymadusa compta
to secondary production in a 140 ha Chesapeake Bay seagrass bed to be 1.7 x
103 kg/year dry weight, ranking it as the 6th largest macroinvertebrate
contributor out of the species examined by these authors.
In addition to their role as a trophic link between primary producers and
secondary consimers (Zimmerman et al. 1979, Nelson 1981a, b),
seagrass-associated amphipods have been shown to be important as potential
removers of epiphytic algae from seagrass blades. Not all amphipods are
equally efficient at reducing seagrass epiphyte loads (van Montfrans et
al. 1984, Duffy et al. 2001), and Hootsmans et al. (1984) noted that C.
compta exhibited intermediate ability to reduce fouling.
VII.
REFERENCES
Bartholomew A. 2002. Faunal colonization of artificial seagrass plots: The
importance of surface area versus space size relative to body size.
Estuaries 25:1045-1052.
Boesch DF and RJ Diaz. 1974. New records of peracarid crustaceans from
oligohaline waters of the Chesapeake Bay. Chesapeake Science 15:56-59.
Bousfield EL. 1973. Shallow-water gammaridean Amphipoda of New England.
Corell University Press, Ithaca, New York. 312p.
Cory RL. 1967. Epifauna of the Patuxent River Estuary, Maryland, for 1963
and 1964. Chesapeake Science 8:71-89.
Cruz-Rivera E and ME Hay. 2000. The effects of diet mixing on consumer
fitness: Macroalgae, epiphytes, and animal matter as food for marine
amphipods. Oecologia 123:252-264.
Cruz-Rivera E and ME Hay. 2003. Prey nutritional quality interacts with
chemical defenses to affect consumer feeding and fitness. Ecological
Monographs 73:483-506.
Duffy JE, MacDonald KS, Rhode JM, and JD Parker. 2001. Grazer diversity,
functional redundancy, and productivity in seagrass beds: An experimental
test. Ecology 82:2417-2434.
Feeley JB. 1967. The distribution and ecology of the Gammaridea (Crustacea:
Amphipoda) of the lower Chesapeake estuaries. Unpublished M.S. Thesis,
College of William and Mary. 75 p.
Fox RS and KH Bynum. 1875. The amphipod crustaceans of North Carolina
estuarine waters. Chesapeake Science 16:223-237.
Fredette TJ, Diaz RJ, van Montfrans J, amd RJ Orth. 1990. Secondary
production within a seagrass bed (Zostera marina and Ruppia
maritime) in Lower Chesapeake Bay. Estuaries 13:431-440.
Hauxwell J, McClelland J, Behr PJ, and I Valiela. 1998. Relative importance
of grazing and nutrient controls of macroalgal biomass in three temperate
shallow estuaries. Estuaries 21:347-360.
Hootsman MJM, Graveland J., van Montfrass J, and RJ Orth. 1984. Laboratory
studies of four peracarid crustacean species grazing on Zostera
marina periphyton in the Chesapeake Bay, USA. Botanica Marina.
Kelly JR, Levine SN, Buttel LA, Carr KA, Rudnick DT, and RD Morton. 1990.
The effects of tributyltin within a Thalassia seagrass ecosystem.
Estuaries 13:301-310.
Luczkovich JJ, Ward GP, Johnson JC, Christian RR, Baird D, Neckles H, and
WM Rizzo. 2002. Determining the trophic guilds of fishes and
macroinvertebrates in a seagrass food web. Estuaries 25:1143-1163.
Marsh AG. 1973. The Zostera epifaunal community in the York River,
Virginia. Chesapeake Science 14:87-97.
McDermott JJ. 1976. Observations on the food and feeding behavior of
estuarine nemertean worms belonging to the Order Hoplonemertea. Biological
Bulletin 150:57-68.
Morgan MD and CL Kitting. 1984. Productivity and utilization of the
seagrass Halodule wrightii and its attached epiphytes. Limnology
29:1066-1076.
Nelson WG. 1995. Amphipod crustaceans of the Indian River Lagoon: current
status and threats to biodiversity. Bulletin of Marine Science 57:143-152.
Nelson WG. 1979. An analysis of structural pattern in an eelgrass (Zostera
marina L.) amphipod community. Journal of Experimental marine Biology and
Ecology 39:231-264.
Nelson WG, Cairns KD, and RW Virnstein. 1982. Seasonality and spatial
patterns of seagrass-associated amphipods of the Indian River Lagoon,
Florida. Bulletin of Marine Science 32:121-9.
Nelson WG and L Demetriades. 1992. Peracarids associated with sabellariid
worm rock (Phragmatopoma lapidosa Kinberg) at Sebastian Inlet,
Florida, USA. Journal of Crustacean Biology 12:647-654.
Rey JR and AW Stoner. 1984. Macroinvertebrate associations on the egg
masses of the sea hare, Aplysia brasiliana Rang (Gastropoda:
Opisthobranchia). Estuaries 7:158-164.
Sheridan PF and RJ Livingston. 1983. Abundance and seasonality of infauna
and epifauna inhabiting a Halodule wrightii meadow in Apalachicola
Bay, Florida. Estuaries 6:407-419.
Stoner AW. 1979. Species-specific predation on amphipod Crustacea by the
pinfish Lagodon rhomboides: Mediation by macrophyte standing crop. Marine
Biology 55:201-207.
Stoner AE. 1980. Perception and choice of substratum by epifaunal amphipods
associated with seagrasses. Marine Ecology Progress Series 3:105-111.
Stoner AW. 1983. Distributional ecology of amphipods and tanaidaceans
associated with three sea grass species. Journal of Crustacean Biology
3:505-518.
Stoner AW, Greening HS, Ryan JD, and RJ Livingston. 1983. Comparison of
macrobenthos collected with cores and suction sampler in vegetated and
unvegetated marine habitats. Estuaries 6:76-82.
van Montfrans J, Wetzel RL, and RJ Orth. 1984. Epiphyte-grazer
relationships in seagrass meadows: Consequences for seagrass growth and
production. Estuaries 7:289-309.
Williams AB and KH Bynum. 1972. A ten-year study of meroplankton in North
Carolina estuaries: Amphipods. Chesapeake Science 13:175-192.
Zimmerman R, Gibson R, and J Harrington. 1979. Herbivory among gammaridean
amphipods from a Florida seagrass community. Marine Biology 54:41-47.
Report by:
J. Masterson, Smithsonian Marine Station
Submit additional information, photos or comments
to:
irl_webmaster@si.edu
Page last updated: October 1, 2008 |
