John P. Manderson

Predator–prey relations between age-1+ summer flounder (Paralichthys dentatus, Linnaeus) and age-0 winter flounder (Pseudopleuronectes americanus, Walbaum): predator diets, prey selection, and effects of sediments and macrophytes

Laboratory experiments and weekly trammel net surveys in the Navesink River, New Jersey (USA) were used to examine the predator-prey interaction between age-1+ summer flounder (Paralichthys dentatus) and age-0 winter flounder (Pseudopleuronectes americanus). Winter flounder (24-67 mm TL) were the dominant piscine prey of summer flounder (n=95, 252-648 mm TL) collected in trammel nets. We observed a temporal shift in summer flounder diets from sand shrimp (Crangon septemspinosa) and winter flounder, dominant during June and early July, to blue crabs (Callinectes sapidus) and other fishes (primarily Atlantic silversides, Menidia menidia and Atlantic menhaden, Brevortia tyrannus) later in the summer. Variations in prey selection appeared to be related to changes in the spatial distribution of predators and spatio-temporal variation in prey availability. In laboratory experiments, summer flounder (271-345 mm total length, TL) preferred demersal winter flounder to a pelagic fish (Atlantic silversides) and a benthic invertebrate (sand shrimp) prey, and the vulnerability of winter flounder increased with increasing prey body size from 20 to 90 mm TL. Experiments testing habitat effects showed that mortality of winter flounder in three different size classes (20-29, 40-49, 60-69 mm TL) was not influenced by sediment grain sizes permitting differential burial of the prey. However, vegetation enhanced survival, with fish suffering lower mortality in eelgrass (Zostera marina, 15+/-0.04%) than in sea lettuce (Ulva lactuca, 38+/-0.04%) or bare sand (70+/-0.07%) when the macrophytes were planted to produce similar leaf surface areas (5000 cm(2) m(-2)). Prey vulnerability appeared to be related to the role of vision in the predators attack strategy and prey activity levels.

Size-related shifts in the habitat associations of young-of-the-year winter flounder (Pseudopleuronectes americanus): field observations and laboratory experiments with sediments and prey

Field surveys and laboratory studies were used to determine the role of substrata in habitat selection by young-of-the year winter flounder. A synoptic field survey of winter flounder and sediments in the Navesink River-Sandy Hook Bay estuarine system in New Jersey demonstrated that winter flounder distribution was related to sediment grain size. Analysis using a generalized additive model indicated that the probability of capturing 10-49 mm SL winter flounder was high on sediments with a mean grain diameter of </=0.5 mm, while fish 50-95 mm were least likely to be collected on fine sediments and most commonly on sediments with a grain-size near 1.0 mm. In the laboratory, sediment preferences and the burying ability of winter flounder (15-69 mm SL) were tested by exposing fish in 10-mm size groups to a choice of azoic sediments of different sediment grain sizes. Smaller individuals (<40 mm SL) preferred fine-grained sediments while larger individuals (>/=40 mm SL) preferred coarse-grained sediments. Burying ability increased with size and all flounders avoided sediments that prevented burial. Subsequent laboratory experiments revealed that the presence of live prey (Mya arenaria) can over-ride sediment choice by winter flounder (50-68 mm SL) indicating the complexity of interrelated factors in habitat choice.

Predation by striped searobin (Prionotus evolans, Triglidae) on young-of-the-year winter flounder (Pseudopleuronectes americanus, Walbaum) : examining prey size selection and prey choice using field observations and laboratory experiments

Laboratory experiments and field observations in shallow water habitats in the Navesink River/Sandy Hook Bay estuarine system (NSHES), New Jersey, USA, were used to examine the predator–prey relationship between the striped searobin (Prionotus evolans: Linnaeus) and young-of-the-year (YOY) winter flounder (Pseudopleuronectes americanus: Walbaum). Striped sea robins (121–367 mm total length [TL]) were present in Sandy Hook Bay but absent from the Navesink River in biweekly gillnet surveys conducted from May through October, 1998. However, juvenile winter flounder were present throughout the estuary during periodic beam trawl surveys. Although mysids and sand shrimp (Crangon septemspinosa, Say: 10–49 mm TL) were the numerically predominant prey of searobins, winter flounder (15–57 mm TL) accounted for an average of 17% (±3) of prey by weight and were found in the diets of 69% of predators collected in June. In the laboratory, searobins (212–319 mm TL) presented with a range of winter flounder sizes (30–114 mm TL) selected prey <70 mm TL (24% of predator TL) and maximum prey size appeared to be constrained by predator esophageal width. When winter flounder (40–60 mm TL) and sand shrimp (30–50 mm TL) were offered at different densities to searobins, the predators fed opportunistically, consuming the prey in proportions similar to initial relative abundances. Laboratory observations showed that searobins rely on modified pectoral finrays to detect, flush, and occasionally excavate buried winter flounder. Our field and laboratory observations indicate that striped searobins consume large numbers of winter flounder in vulnerable size classes (15–70 mm TL) in habitats where the two species co-occur. Patterns in the distribution of the two species in the NSHES suggest that predation probably varies spatially in the estuary, with flounder more at risk in nurseries in Sandy Hook Bay than in the Navesink River, which may serve as a spatial refuge for winter flounder from searobin predation during some years.

Stage-specific spatial and temporal variability in the diets of larval winter flounder (Pseudopleuronectes americanus) in a northeastern U.S. estuarine nursery

Collections of winter flounder (Pseudopleuronectes americanus) larvae were made biweekly from March to May in 1999 and 2000 in the Navesink River-Sandy Hook Bay estuarine system, New Jersey, to determine stage-specific spatial and temporal variability in diets. Relatively high percentages of larvae with empty guts were found at low water temperatures. Percentages of empty guts did not differ by larval stage (preflexion and postflexion) or region of collection (river and bay). There was high intraregional variability in percentages of larvae with empty guts. Nauplii, invertebrate eggs, and polychaete larvae were dominant prey items followed by tintinnids, bivalve and gastropod veligers, and diatoms. Ontogenetic dietary shifts were evident in both years. Preflexion winter flounder largely consumed nauplii, invertebrate eggs, and tintinnids; postflexion winter flounder consumed the largest prey (polychaete larvae) but also retained small prey items in their diets. Water temperature significantly affected the percentages of larvae feeding on nauplii (p<0.05) and tintinnids (p<0.08) in 2000. Region of collection was not significantly related to diets because of high intraregional variability. Fine scale spatial (within regions, stations were approximately 3 km apart) and temporal (weeks) dietary variation of larval winter flounder could result in accompanying variation in development, growth stage duration, and survival.

The Importance of Federal and Regional Partnerships in Coastal Observing

Abstract Congress designed the U.S. Integrated Ocean Observing System (IOOS) as a partnership of 17 Federal agencies and 11 regional systems. Through collaborative projects and shared objectives, these partnerships improve the understanding of the coastal ocean environment by increasing the data available for modeling and analysis, improving forecasting capabilities, and through new decision support tool innovations. This chapter describes the benefits of IOOS partnerships and highlights five case studies. The case studies focus on enhancements to fisheries management, drinking water management, prediction of harmful algal blooms, and the benefits of a dedicated coastal ocean modeling testbed that intentionally brings together the research and operational communities.