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Ichthyoplankton data sets based on collections from estuaries in South Carolina, North Carolina, Virginia, Delaware, and New Jersey and from ocean cruises off the U.S. East Coast were examined to determine spawning locations in the ocean, cross- shelf distributions of larvae, and movements of spot (Leiostomus xanthurus) into estuaries. Spot spawn during fall and winter near the edge of the continental shelf, primarily south of Cape Hatteras in North Carolina. We documented additional spawning of spot north of Cape Hatteras, close to the coast, in summer and fall. Larval and early juvenile spot enter estuaries from November through May in South Carolina and North Carolina and from January through June in Virginia, Delaware, and New Jersey. Numbers of spot per volume of water sampled decreased from south to north among estuaries and in the ocean. Interannual variations in abundance were high, and no long- term trends were determined. Over the decades, median annual lengths of ingressing larval and juvenile spot decreased as annual mean water temperature increased in South Carolina and North Carolina. The timing of ingress was positively correlated with water temperature. Continued increases in water temperature on the East Coast will likely lead to additional changes in oceanic distribution and ingress patterns of spot. Our findings indicate the value of synthesizing information from long- term studies conducted across broad geographic scales. [ABSTRACT FROM AUTHOR]

We investigated long-term changes in copepod community body size in a temperate estuary in the Southeastern United States. Mesozooplankton samples were collected twice each lunar cycle from 1981 to 2020 during the months of March to July. We found strong evidence for a long-term increase in body size, likely driven by shifts in species composition, with the most rapid increase occurring during the most recent decade (2011–2020). Between the 1980s and 2010s, we documented an increase in the proportion of Oithona spp. (small species) and Acartia tonsa and Pseudodiaptomus pelagicus (large species) and decreased proportion of Parvocalanus crassirostris (small species). Temperature was inversely related with monthly mean body size, potentially driving the seasonal shifts in size, but was not correlated with the observed long-term trend. We detected strong seasonality in the normalized biomass size spectra slope, but the slope for each month did not vary interannually with changes in temperature. Overall, our study showed a long-term increase in copepod community body size that was not directly linked to changes in temperature but instead to changes in species composition. [ABSTRACT FROM AUTHOR]

The naked goby ( Gobiosoma bosc ), striped blenny ( Chasmodes bosquianus ), and eastern oyster ( Crassostrea virginica ) are common resident species in temperate Atlantic tidal waters. All three species produce planktonic larvae, and interactions between their early life stages likely influence recruitment success. Fish predation on oyster veligers requires co-occurrence as well as a match between prey behavior, size, and morphology and the ability of the predator to capture and engulf the veliger (prey). Wild plankton, oyster veligers, and wild plankton enriched with oyster veligers (mixed) were fed to cultured larval fishes during laboratory experiments. Three hypotheses were tested: (1) no fish species-specific differences in oyster veliger consumption exist within similar predator–prey development stage combinations, (2) postflexion blennies and gobies consume more veligers than preflexion fishes, (3) veligers reach a size refuge from fish predation by the umbo developmental stage. The resulting data provide a quantitative description of larval fish feeding behavior with respect to fish (preflexion, postflexion) and veliger (straight hinge, umbo) developmental stage. Selectivity for bivalve veligers as well as ontogenetic effects on the predator–prey interaction were examined. Fish nests were cultured to provide larval fish predators of known age. Overall, 70% of striped blennies and 59% of naked gobies consumed at least one prey item during the 3 h experiments. There were fish species-specific differences in oyster veliger consumption between striped blennies and naked gobies. Striped blennies consumed more prey items including a wider range of veliger ages than larval naked gobies of the same developmental stages, regardless of the prey treatment. Fish selectivity was high for copepod nauplii and bivalve veligers and usually low for polychaete larvae, barnacle nauplii, and diatoms. There was a significant positive relationship between standardized consumption and predator development stage in the wild treatment for both fishes and in mixed and veliger treatments for blennies. All fishes consumed straight hinge veligers more often than umbo stage veligers. The largest veligers appear to reach a predation refuge from both fishes. Larval gobies and blennies are generalist predators that use seasonal pulses of zooplankton prey within temperate estuaries. Potential mismatches between predator–prey spatial and temporal overlap that might reduce fish recruitment are likely offset by adult spawning strategies that result in multiple nests within a long spawning season. [ABSTRACT FROM AUTHOR]

Motile organisms are thought to play a role in biogeochemical cycles in tidal systems, but few studies have addressed links between animal activities and dissolved nutrients. Our observations and experiments indicated that movements, feeding, and excretion by fishes and shrimps resulted in subsidies of and to intertidal salt marsh creeks. During low tide, isolated pools inhabited by nekton became biogeochemical hotspots with up to fivefold increases in water column nutrient concentrations. In field experiments, simultaneous measurements in artificial pools and an adjacent natural intertidal pool demonstrated that nekton were sources of during day and night, contributing 17-109% of the net increase in and 3-18% of the in the natural intertidal pool. Nekton residing in intertidal pools generated the equivalent of 5% of the total imported to the creek. At night, nekton in pools contributed the equivalent of 12% of the and 4% of the imported from the subtidal channel. As the tide flooded the intertidal creek, nutrient enriched pool water was pulsed up the creek and into the intertidal basin. Tidally controlled patterns of nekton movements and feeding result in retention and reintroduction of nutrients to the upper reaches of intertidal creek basins. Accordingly, nekton contribute to the recycling of nutrients through a positive feedback loop that may enhance primary production and invertebrate prey within salt marsh creek basins. We conclude that nekton can be important and underappreciated contributors of dissolved nutrients in tidal systems. [ABSTRACT FROM AUTHOR]

Biotic factors such as interactions among co-occurring taxa are frequently cited as important in determining how nekton use habitat, yet their effects have rarely been tested experimentally. We investigated the general hypothesis that depth distributions of five taxa common in salt marsh intertidal creeks are affected by the presence of other taxa. Two experiments were conducted in a pair of large (15m3), multi-level (20, 40, and 60cm water depth) flow-through tanks under fairly stable environmental conditions. During the first experiment, when grass shrimp (Palaemonetes spp.), mummichog (Fundulus heteroclitus), white mullet (Mugil curema), spot (Leiostomus xanthurus), and pinfish (Lagodon rhomboides) were each tested alone, the highest proportions of individuals occupied the intermediate and deepest depths. When all taxa were tested together, the distributions of resident creek taxa, mummichog and grass shrimp, shifted to shallower depths, but the distributions of the seasonal transient taxa, white mullet, spot, and pinfish, did not change. A second experiment was conducted to test the effect of predator presence on grass shrimp depth selection. Neither predatory pinfish nor non-predatory white mullet had a strong influence on grass shrimp depth distribution when tested separately, but grass shrimp shifted to shallower depths in the combined presence of both fish. This suggests that a multiple-taxa effect such as increased disturbance or higher encounter frequency influenced the depth selection of grass shrimp. Our results demonstrate that biotic factors are important in shaping distributions of grass shrimp and mummichog in shallow water habitat. [Copyright &y& Elsevier]

The release of inorganic nutrients by nekton (fish and shrimp) assemblages through excretion and bioturbation was quantified for intertidal creeks in a warm-temperate estuary, North Inlet, South Carolina, USA. Excretion rates for individual nekton taxa were determined for captive animals maintained in the field. Nutrient production by nekton assemblages was determined in laboratory tank experiments in which the effects of nutrient releases through excretion and bioturbation could be separated. These values and field-measured biomass data were used to calculate and compare nutrient generation rates by nekton to those of other biotic and abiotic sources in intertidal creeks. Mass specific ammonium excretion rates ranged from 5.7–11.9 μmol g dw-1 h-1 in early spring to 8.3–20.7 μmol g dw-1 h-1 in the summer. Orthophosphate excretion rates were distinctly lower and never exceeded 3 μmol g dw-1 h-1. The N/P ratio in the excretory products of the different taxa was generally higher during summer than in early spring. In the summer, experiments on nekton assemblages in tanks indicated that mass specific ammonium production rates based on excretion plus bioturbation were on average 40% higher than rates based on excretion alone. Orthophosphate production was unaffected by bioturbation during both seasons.Nekton, oyster reefs, and benthic remineralization were identified as the major sources for inorganic nutrients. These observations and the fact that consumer driven nutrient cycling through nekton has not been recognized as an important process in coastal ecosystems suggest that additional efforts to quantify the role of large motile animals are needed. [Copyright &y& Elsevier]

Depressional wetlands provide habitat for birds, mammals, reptiles, amphibians, invertebrates, and rare plant species. In order to protect, restore, and manage depressional wetlands, it is important to know more about the vegetative composition and productivity of these systems. The species composition and aboveground productivity of three seasonally flooded depressional forested wetlands were studied on the coastal plain of South Carolina from January 2000 to January 2001. The dominant tree species in the depressions were Taxodium distichum [L.] Rich., Nyssa aquatica L., and Nyssa sylvatica var. biflora [Walt.] Sarg. Annual diameter at breast height (dbh) growth was measured for all trees >10 cm dbh in five 20 x 25 m plots within each depression, and changes in dbh were used to estimate annual biomass and stem production. Aboveground net primary productivity (ANPP) was calculated for each wetland by summing stem and leaf litter production. There were no significant differences in ANPP among sites, ranging from 564-774 grams/m²/yr. These ANPP values are similar to values reported for slowly flowing forested wetland systems of the southern United States. [ABSTRACT FROM AUTHOR]