Silversides, continued 



1973, Benson 1982). Habitats include lagoons, estu- 

 aries, bays, marshes, beach passes, ponds, rivers, 

 canals, and lakes (Gunter 1945, Bailey et al. 1954, 

 Gunter 1958, Arnold etal.1 960, SpringerandWoodburn 

 1960, Hellier 1962, Tilton and White 1964, Hoese 

 1965, Parker 1965, Perret et al. 1971, Wilson and 

 Hubbs 1972, Christmas and Waller 1973, Wagner 

 1973, Cornelius 1984, Loftus and Kushlan 1987). 

 Habitat partitioning among/W. beryllina, M. peninsulae, 

 and M. clarkhubbsi has been noted in a study in 

 Copano Bay, Texas (Echelle and Echelle 1997). M. 

 peninsulaewere found primarily in seaward bays and 

 connected tidal pools with mesohaline, polyhaline, and 

 euhaline salinities. M. beryllina were predominant in 

 freshwater streams and bays, isolated pools, and tidal 

 creeks with limnetic, oligohaline, and mesohaline sa- 

 linities. Both species, their hybrids, and/W. clarkhubbsi 

 co-occured in shallow bays and tidal pools with 

 mesohaline salinities. 



Substrate : Little preference for bottom type has been 

 demonstrated for Menidia species, with collections 

 made over sand, mud, shell, clay, clay-shell, clay- 

 sand, and silt-clay (Simmons 1 957, Hoese and Jones 

 1 963, Swingle 1 971 , Benson 1 982). One report does 

 state abundances are greatest over bottoms with a 

 high sand content and low percentage of organics. 

 Silversides are particularly common near inundated 

 terrestrial plants and aquatic vegetation such as 

 Thalassia (Hildebrand 1922, Kilby 1955, Hoese and 

 Jones 1963, Zimmerman 1969, Franks 1970, Fisher 

 1 973, Swingle and Bland 1 974), and are often associ- 

 ated with some sort of structure such as islands, piers, 

 and oyster reefs (Benson 1982). 



Physical/Chemical Characteristics : Menidia species 

 are considered to be eurythermal and euryhaline 

 (Gunter 1 956, Renf ro 1 960, Franks 1 970, Middaugh et 

 al. 1985), but temperature and salinity are factors 

 affecting their distribution (Kilby 1955, Renfro 1960, 

 Springer and Woodburn 1960, Swingle 1971). In 

 general, M. beryllina is considered to be most abun- 

 dant at salinities <19%o, whereas M. peninsulae is 

 found primarily at >15%o (Middaugh et al. 1986). 



Hubbs etal. 1971, Bengtson 1985). 



Temperature - Juveniles: Juvenile Menidia have been 

 collected in the wild from 5.0° to 33°C (Garwood 1 968, 

 Franks 1970, Perret et al. 1971, Pineda 1975, Bonin 

 1 977). Peaks in numbers have been reported at 26.5° 

 and 21.8°C (Bonin 1977). In one study in Mississippi 

 Sound, temperature ranges in which different juvenile 

 Menidia size classes were found are: 26.4° to 28.4°C 

 for fish whose total length (TL) was 1 4 to 22 mm; 21 .0° 

 to 31 .8°C for 23 to 36 mm TL; and 21 .0° to 32.5°C for 

 40 to 44 mm TL (Garwood 1968). 



Temperature - Adults: Adult Menidia sampled in Gulf of 

 Mexico estuaries have been found from 5.0°C to 34.9°C 

 (Chambers and Sparks 1959, Renfro 1960, Franks 

 1970, Perret et al. 1971, Christmas and Waller 1973, 

 Perret and Caillouet 1974, Pineda 1975, Tarver and 

 Savoie 1 976, Barrett et al. 1 978, Middaugh et al. 1 985) 



Salinity - Eggs: Eggs of Menidia species have been 

 observed in the field at salinities ranging from 0.0 to 

 31.5%o (Fisher 1973, Garwood 1968, Hubbs et al. 

 1 971 ). One laboratory study of M. beryllina (reported 

 as M. audens) from Lake Texoma, a freshwater reser- 

 voir, noted salinity affecting temperature tolerance 

 limits of eggs: no survival at 100% seawater (33%o); 

 normal range of 1 7° to 33°C at 25% seawater; 1 9° to 

 33° at 50% seawater; and only 22° to 31 .3°C at 75% 

 seawater (Hubbs et al. 1971). In other words, M. 

 beryllina eggs become more stenothermal as salinity 

 increases. Middaugh et al. (1986) collected adult 

 Menidia from northwest Florida, and compared the 

 survival of M. beryllina and M. peninsulae embryos 

 incubated at an array of salinities. M. beryllina were 

 euryhaline, with 73-78% survival at 5, 1 5, and 30%o. M. 

 peninsulae embryos had 90% hatch at 5%o, but only 

 65% hatch at 30%o, suggesting that it is the less 

 euryhaline species at this life stage. 



Salinity- Larvae: The recorded salinity range for/Wen/d/'a 

 larvae is 0.0 to 30%o, with higher concentrations of 

 larval M. beryllinaoccumng at 2 to 8%o (Garwood 1 968, 

 Martin and Drewry 1978, Bengtson 1985). 



Temperature - Eggs: Eggs of Menidia beryllina have 

 been observed to develop from 13.2° to 34.2°C 

 (Hildebrand 1922, Garwood 1968, Hubbs et al. 1971, 

 Fisher 1 973, Hubbs 1 982, Middaugh et al. 1 985). High 

 survival was recorded from 17.0° to 33.5°C and opti- 

 mum survival occurred from 20.0° to 25.0°C. Upper 

 lethal limit for eggs is about 35.0°C (Hubbs et al. 1 971 ). 



Temperature - Larvae: Larvae of Menidia beryllina 

 have been raised under laboratory conditions and 

 collected in the field over a temperature range of 21 ° + 

 1°C to 30° ± 1° (Hildebrand 1922, Garwood 1968, 



Salinity - Juveniles: Juvenile Menidia have been col- 

 lected in the wild from 0.0 to 34.5%o salinity (Gunter 

 1945, Gunter 1950, Garwood 1968, Franks 1970, 

 Pineda 1 975, Bonin 1 977, Martin and Drewry 1 978). In 

 Mississippi Sound, juvenile Menidia are reported to 

 occur by size class in the following salinities: 3.3 to 

 1 9.4% for fish 1 4 to 22 mm TL; 2.2 to 23.8%o for 23 to 

 36 mm TL; and 2.2 to 28.3%o for 40 to 47 mm TL 

 (Garwood 1968). 



Salinity - Adults: Adult Menidia are reported to be 

 abundant up to 45%o (Simmons 1957), and present in 



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