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Length frequency data for fishes and turtles from polyhaline subtidal and intertidal marsh creeks in southern New Jersey
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This report documents length frequency data for 31 of the most abundant fishes and the diamondback terrapin, which use salt marsh creeks located in the Great Bay-Little Egg Harbor estuary in southern New Jersey. A general description of seasonal abundance and biomass characteristics of the fauna are presented elsewhere for subtidal and intertidal marsh creeks. The goal of this report is to provide length frequency data to investigators interested in interpreting life history patterns, characterizing life history stages that use marsh habitats, and estimating growth rates of selected species.
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In order to determine the dynamics of dissolved oxygen (DO) in salt marsh pools and its effect on their respective fish assemblages, DO was measured in 5 high-salinity pools in a Spartina alterniflora marsh in southern New Jersey over ten 24 h periods, from 2 July to 22 October 1990, to determine daily and monthly fluctuations. Typically, DO peaked at approximately 16:00 h, and reached a minimum by about 05:00 h. The greatest variation occurred in mid-July, when DO ranged from over 20 ppm at midday, to 0 ppm in the early morning. From mid- to late August, DO remained at very low concentrations (<1.0 ppm) for long periods (11.7 +/- 1.7 h). DO concentrations varied among marsh pools, but there was no interaction between pool and time of day. The young- of-the-year (YOY) of the dominant 5 species of fishes in these pools were tested for tolerance and behavioral responses to low DO in laboratory aquaria. Fundulus heteroclitus survived the longest at low DO, and Menidia menidia was least tolerant. Aquatic surface respiration (ASR) was the primary behavioral response to low DO for all species tested. All species, including Cyprinodon variegatus, Lucania parva, and M beryllina, survived at DO < 0.5 ppm when they used ASR; however, when fish were denied access to the air-water interface, only F. heteroclitus was able to survive more than 1 h. All species initiated ASR at ca. 1 ppm, with the exception of M menidia, which began ASR at 2.6 ppm and survived only at higher concentrations of DO. In summary, although the salt marsh pools showed extreme diurnal variability in DO, with rapid drops from supersaturation to anoxic conditions, all of the fish species, with the exception of M menidia, were well adapted to survive these fluctuations. This lack of tolerance to low DO by M menidia may seasonally limit its occurrence in marsh pools, but this is not the case for the congener M beryllina, or the other resident fishes.
The calcium content of flatback (Natator depressus), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), and green (Chelonia mydas) sea turtle eggshells are not significantly different. Green turtle eggs with external fungal invasion by Fusarium solani had significantly reduced calcium content of the outer, inorganic portion of the eggshell.
Population structure of Malaclemys terrapin terrapin in an unaltered creek in southern New Jersey was compared to data collected 12–13 years earlier. I found significantly lower average carapace size of terrapins and lower frequency of adult females compared to the earlier survey, and speculate that road mortality of nesting females may be responsible for these trends.
Allometric growth and sexual dimorphism of the shell is evident in Malayemys macrocephala from the Chao Phraya River Basin of central Thailand. Differences in allometric growth between males and females produce sexually dimorphic adults. Adult females exhibit larger sizes and have relatively wider and higher shells and longer plastra than males.
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