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In 2002, we began tagging macrofauna and established an array of hydrophones in the Mullica River and Great Bay estuary in southern New Jersey, USA, as part of an observatory for the study of migration. The hydrophone array differs from other model telemetry programs in several aspects. The wireless radio‐linked design provides the capability to couple observation in real time with reactive sampling schemes (including mobile tracking), provides for public interaction via frequent updates to a Worldwide Web‐based distance learning program, and saves ship time. However, the wireless design is more amenable to a turnstile‐like acoustic gate than to positioning, and strategic positioning of hydrophones at bottlenecks is favored over continuous contact of transmitters within the large study area. The hydrophone array is supplemented by infrastructure from two existing marine observatory programs focused on physical processes. These are the Long‐term Ecosystem Observatory (LEO‐15) outside the estuarine inlet and the System‐Wide Monitoring Program of the Jacques Cousteau National Estuarine Research Reserve (JCNERR) within the river and estuary. This article outlines considerations in the design and implementation of the array from infrastructure, predeployment survey, and biological considerations through hydrophone placement, maintenance, calibration, and data collection. Further, it presents a comprehensive description of the observatory and study area for reference in works on the biology of those organisms under study. The hydrophone array serves as a unit intended for stepwise extension into other estuaries to assist in our understanding of habitat use and of those species that use estuarine habitat during coastal migration.

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Total ascorbic acid was measured in the gonads of North Sea dab (Limanda limanda) throughout one reproductive cycle. In the ovaries, the concentration of ascorbate began to increase during the resting period in summer and reached maximum values of 400 µg⋅g fresh weight (fw) -1 at the onset of ovary maturation in fall. Concentrations declined rapidly towards the spawning period in spring and reached the lowest values of 80-100 µg⋅g fw -1 . The maximum deposition of ascorbate in the ovaries amounted to 2.5 mg⋅organ -1 and occurred in late winter, corresponding to the beginning of the spawning period. In the testes, ascorbate concentrations were lower than in the ovaries, reaching a maximum of 170 µg⋅g fw -1 in early fall. The lowest values of 20-60 µg⋅g fw -1 appeared in winter and spring. In the testes the highest deposition of ascorbate amounted to 110 µg⋅organ -1 and appeared at the beginning of maturation. The sexual differences and seasonal variations are discussed in relation to the reproductive biology of dab.Résumé : L'acide ascorbique total a été mesuré dans les gonades des poissons Limande (Limanda limanda) de la mer du nord durant un cycle reproductif complet. Dans les ovaires les concentrations de l'acide ascorbique total commencent à augmenter durant la période de repos (été), et atteignent des valeurs maximales de 400 µg⋅g poids frais (pf) -1 durant l'automne; c'est à dire au début de la croissance des ovaires. Au printemps, les concentrations ont chuté rapidement avant la période de fraye, et ont atteint des concentrations minimales de 80 à 100 µg⋅g pf -1 . Vers la fin de l'hiver, la déposition maximale de l′acide ascorbique était de 2.5 mg⋅organe -1, correspondant au début de la période de fraye. Au début de l′automne, dans les testicules, les concentrations de l'acide ascorbique total étaient moins que dans les ovaires atteignant une valeur maximale de 170 µg⋅g pf -1 . En hiver et au printemps, des concentrations minimales de 20 à 60 µg⋅g pf -1 ont été atteintes. Au début de la maturation, la déposition d′acide ascorbique dans les testicules était de 110 µg⋅organe -1 . La différence sexuelle et les cycles saisonièrs sont mis en relation avec la biologie de reproduction du limande.