Barbara E. Warkentine

The First Record of Palaemon macrodactylus (Oriental Shrimp) from the Eastern Coast of North America

Abstract Palaemon macrodactylus (Oriental Shrimp), native to estuarine waters of Southeast Asia, has been reported outside of its native range. The spreading of this species to new regions has been well documented, and its disjunct distribution strongly speaks for its transport being attributed to ballast water. In this paper, we report the first record of P. macrodactylus from the eastern coast of the United States and in the estuarine system of New York City (NYC). While this animal has been reported to have crossed the Pacific, and has been found in the eastern Atlantic along the coasts of Spain, France, Germany, and the British Isles, and in the southwestern Atlantic off the coast of Argentina, it has not been previously sighted in the northwest Atlantic. Our preliminary life-history data indicate that the size range for the 98 adult individuals in the 2001 collection was from 2.05 to 5.05 cm, and exhibited a one-to-one sex ratio. The finding of gravid females among these shrimp collected from 2001–2002 and again in 2008 indicates that the oriental shrimp populations in the coastal waters of NYC have become established, and show reproductive activity from May through October. Further studies are required to evaluate whether P. macrodactylus poses a threat to native aquatic organisms in this region.

Feeding Preference of Sympatric Hake from the Inner New York Bighta

A total of 156 Urophycis regia, 133 U. chuss, and 145 U. tenuis originally collected from the Brigantine Shoals area off Little Egg Harbor, New Jersey, and part of the permanent fish collection of the Department of Ichthyology of the American Museum of Natural History, New York, were examined for their dietary diversity, evenness, overlap, and preference. The size ranges of these fish were, respectively, 5.3-20.6 cm, 6.0-32.4 cm, and 4.713.4 cm standard length. Length-frequency histograms and scale analyses indicated that all fish were juveniles. Diet diversity was computed by the Shannon Information Index: evenness by the Heip Evenness Function,s2 overlap by both the Schoener Similarity Index and the Morisita Overlap Index: and finally preference by the Relativized Electivity (P) of Vanderploeg and Scavia:o E+ = (W ( l / n ) ) / (W + ( l /n ) ) , where W is the Manly Preference Index and n = the number of kinds of food items. Stomachs were removed from all fish and the stomach contents were identified to the lowest practicable taxon and enumerated. An estimate of the environmental food resource base available to these fish was achieved by pooling the stomach contents of all 434 animals. Dietary data from the pooled stomach contents indicated that the resource base consisted of mysids, Neomysis americana, the decapod crustacean, Crangon septemspinosa, the amphipods, Aeginella longicornis, Calliopus laeviusculus. Gammarus annulatus, G. marinus, Microdeutopus gryllotalpa. and Pontogenia inermis, the isopod, Edotea montosa, the copepod, Acartia sp., unidentified nematodes and the fish, Etrumeus teres (round hemng). While these were the dominant food items, the fish also fed on the mysid, Mysidopsis bigelowi, and larve of the decapods, Libinea emarginata, Cancer borealis, C. irroratus, the copepod Temora sp., and the polychaete, Nereis virens. TABLE 1 shows both the diet of the three hake species and the similarity and overlap in their feeding patterns. From these data it can be seen that U. regia and U. tenuis have a 48.4% similarity and a 0.64 overlap in diet. U. regia and U. chuss have a 70.8% similarity and a 0.95 overlap, while U. tenuis and U. chuss have a 57%

Resource Partitioning in a Stream Fish Communitya

A first-order approximation for understanding how members of a fish community allocate available food resources can be achieved through an assessment of the degree of diet similarity found within the community. One method of studying this is to sample a discrete community over a collecting season and to evaluate the degree of diet overlap among the members. The purpose of this study was to examine the diet of concurrently collected fish from a single pool over a collecting season, in order to assess the degree of dietary overlap and similarity, and to evaluate this as a measure of the potential for competition among closely related species. To accomplish this, a section of the Waccabuc River in Westchester County, New York was chosen for the study. The study area is characterized by well-defined pools and rifles. One such well-defined pool was chosen as the study site and sampled monthly from March-November. In addition to fish collections, reference collections of potential invertebrate food resources were made using Surber nets and Dendy plates. These plates were placed in the pool and harvested monthly. Fish specimens were collected using a backpack electroshccker. Both fish and invertebrates were preserved and returned to the laboratory for analysis. The stomach contents of each fish was identified to the lowest possible taxon and enumerated. Dietary overlap among the members of the fish community sampled from the pool study site was then evaluated using the Morisita overlap index as modified by Horn, and the Shoener similarity index. TABLE 1 presents the diet, and food item proportions, for each of the 12 species of fish comprising the discrete freshwater pool community of this study. From these data, pairwise comparisons of diet overlap and similarity were calculated and these data are presented in TABLE 2. The study pool contained three congeneric centrarchids, Lepomis auritus, L. macrochirus, and L. gibbosus. The data in TABLE 1 indicate interesting differences in their diets. All pairwise comparisons of these three species (TABLE 2) indicates no significant overlap and minimal diet similarity during the study period. With the suggested value of 0.6 as the cut-off for significant overlap: it can be seen from the data that the redbreast sunfish and the fallfish have significant diet overlap; the same is true for the bluegill and the large-mouth bass; and also for

Population Dynamics of the Atlantic Silverside, Menidia menidia

A total of 1604 Menidia was collected biweekly from September 1979 to September 1980 at Orchard Beach (Long Island Sound, 40°52”:73047’W). Scale and otolith examination revealed two age classes in the population: O+ fish (standard length c95 mm) and 1 + fish (standard length L 95 mm). Of the 1604 Menidia collected, 97% were O+ fish and 3% were I + fish. This indicates that Menidia from this area have a relatively short life span. Since the majority of the population is represented by O+

Growth Characteristics of Two Sympatric Species of Flatfisha

E2 Four-spot flounders (Paralichthys oblongus) and yellowtail flounders (Limanda ferruginea) occur sympatrically in the New York Bight and respectively represent two families of flatfish, Paralichthyidae (left-eyed) and Pleuronectidae (right-eyed). Since both species are commercially important, knowledge of their population dynamics are essential for management purposes. A total of 66 four-spot flounders and 70 yellowtail flounders were collected from the New York Bight in June 1982 using a standard 3/4 Yankee trawl net, with a 10-foot throat and a 45-foot sweep, in order to determine the growth characteristics of these two populations. Standard lengths (cm) and weights (kg) were recorded for each fish and scales examined for annular growth rings. Four-spot flounders ranged in size from 15.8-29.0 cm standard length (S.L.), and

Population Growth of the Atlantic Red Hake from the Outer New York Bight

2.0 25 30 35 4.0 A total of 141 red (squirrel) hake (Urophycis chuss) was collected in June 1982 from three sites (39O43”:72O18’W; 39O48’N:72O27’W; 39O41’N:72O32’W) a t the outer margin of the New York Bight adjacent to the Hudson Canyon, representing stations at the northeast and southwest sides of the head of the canyon. Water depths were 100,74, and 76 meters, respectively, for the three collection sites. Fish were collected using a standard ’/4 Yankee trawl net, with a 10-foot throat and a 45-foot sweep. The fish ranged in size from 18.W3.3-cm standard length (S.L.). Regression of weight on length was best described by a second-order polynomial (Y = 0.001X2 0.034X + 0.321) with r2 =