Species with complex life cycles often occupy multiple habitats during different life stages. Shrimps in the genus Penaeus are globally distributed, play important roles in food webs, and support valuable fisheries. Before recruiting to the benthos, planktonic stages (e.g. postlarvae) ingress into estuaries. We conducted biweekly collections of postlarval penaeids for 37 yr (1981-2017) in the North Inlet estuary, South Carolina, USA, which revealed seasonal and interannual patterns and trends for white Penaeus setiferus, brown P. aztecus, and pink shrimp P. duorarum. Despite being rare as juveniles or adults in our region, pink shrimp were the most abundant species as postlarvae, identifying the postlarval-juvenile transition as the population bottleneck in the region. During our 4-decade study, postlarval white and brown shrimp abundance increased, and the increase in white shrimp was positively correlated with increasing mean winter water temperature. Abundance of white shrimp was also substantially higher after warm winters. Conversely, the seasonal peak in brown shrimp abundance was more compressed following cold winters. While long-term trends in salinity were not apparent, both brown and white shrimp annual abundance declined as salinities increased, possibly indicating salinity-mediated decreases in estuarine ingress. Generally, increasing postlarval abundances as water temperatures increase suggests that long-term environmental changes have been favorable to penaeid shrimp in South Carolina, located near the northern limits of their distributions. However, changes in the timing of occurrence in response to environmental change raises questions about the structure and stability of estuarine communities considering the important roles these species play in estuaries.

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 con-ducted across broad geographic scales.

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.

Estuarine nekton (fishes, crabs, and shrimps) play key ecological roles and support valuable commercial and recreational fisheries. Long-term research programs focused on nekton can provide insight into community and population-level changes over time, but are uncommon due to funding and logistical constraints. We describe patterns and changes in a nekton assemblage from an intertidal creek in the North Inlet estuary, South Carolina, USA based on 19 years of observations. From 1984 to 2002, biweekly seine collections (approximately every 2 weeks, n = 469) were made in a pool isolated within an intertidal creek at low tide. The assemblage was composed of juvenile and small adult (mostly < 100 mm) fishes, shrimps, and crabs. The 10 most abundant species made up > 97% of the catch; these species included (in descending order): Leiostomus xanthurus , Litopenaeus setiferus , Fundulus heteroclitus , Mugil cephalus , Farfantepenaeus aztecus , Eucinostomus spp., Mugil curema , Fundulus majalis , Menidia menidia , and Brevoortia tyrannus . The assemblage exhibited a distinct seasonality across years, with peak total abundance in mid-spring, peak total biomass in late spring, and highest species richness in late summer and early fall. Total abundance and species richness showed evidence of significant increases across years, total biomass and the Shannon diversity index remained unchanged, and evenness significantly declined. The composition of the assemblage shifted during the sampling period, with the abundance of key year-round residents ( F. heteroclitus , M. cephalus ) decreasing and warm-season species ( L. xanthurus ) increasing. Most of the five metrics of the nekton assemblage and the abundances of the five top species were positively correlated with both water temperature and salinity. Direct and indirect effects of hurricanes and storm events on the hydrogeomorphology of the creek and pool were also recognized as influences on the long-term patterns and trends. Long-term (decadal) sampling programs like this can provide important baseline information, and thus insight into the influence of significant weather events and global climate change on nekton populations and their roles in ecosystem dynamics, as well as inform the management of estuaries and fisheries in the southeastern US.

Coincidental long-term changes in estuarine nekton assemblages and environmental conditions are widely reported. In this study, from a warm-temperate, high salinity, salt marsh-dominated estuary in the southeastern USA, decreases in overall abundance, shifts in species and life stage composition, and changes in seasonal patterns of occurrence coincided with increased water temperature. Biweekly trawl collections in a subtidal creek were made during two 4-year periods separated by more than 30 years. Of the total 111 taxa in the North Inlet estuary, South Carolina, 64% (71) occurred during both the historic (1981–84) and recent (2013–16) periods. The top five species and their proportions of the total annual catches changed between periods. In the recent study period, near-bottom species (Lagodon rhomboides, Bairdiella chrysoura, Litopenaeus setiferus) increased, and pelagic species (Anchoa spp. and Lolliguncula brevis) decreased. The mean abundance of total nekton in the recent period was approximately 50% of historic abundance. Large, but temporary increases in nekton abundance occurred when salinity decreased after major storms. In the recent study period, shifts in the timing of peak abundances from spring to fall, the occurrence of juveniles during winter, and increased diversity suggested responses to significantly warmer winters and summers. Over the 30 year period, the subtidal nekton assemblage transitioned to a state of lower abundance and different composition. Future increases in water temperature, incidences of major storms, and modifications of estuarine habitats due to rising sea level could lead to additional changes in the fauna of warm-temperate estuaries.

Blennies and gobies are among the most abundant fishes in western Atlantic and Gulf of Mexico estuaries. They establish nests and maintain territories in oyster reefs and around other shallow-water structures during warm months. In this study, site fidelity and movements were determined for adult striped blenny , naked goby, freckled blenny , crested blenny , and feather blenny, in descending order of abundance. Recaptures among 221 tagged fishes at nine intertidal oyster reefs in a southeastern U.S. saltmarsh estuary provided information about fidelity for individual oyster reefs and nest sites as well as the size of territories (areas used) around nest sites. An overall recapture rate of 94% for fishes on reefs where they were tagged indicated high fidelity. Total recapture rates for the four blenny species ranged from 38 to 50%, but the naked goby recapture rate was only 9%. Within a breeding season, fidelity for specific nest sites was 58% for all blennies and 17% for gobies. Movements away from nest sites were limited with 56% of all fishes re-occurring ≤ 1 m from the original tagging site. Territories of < 5 m were identified for > 84% of the recaptured fishes. Differences in species composition and abundance between reefs suggested species-specific preferences for habitat features. Crested blenny and freckled blenny were recaptured at nest sites with significantly more oyster cover than nest sites occupied by striped blenny. Blennies occupied nest sites for several months and across annual breeding seasons suggesting continued residency within small areas of individual oyster reefs throughout their lives. Strong fidelity for reefs and nest sites potentially makes blennies more susceptible to disturbances than gobies, but both may be vulnerable to habitat disturbance at scales < 5 m. Thus, blennies and gobies may be useful indicator species for changes within estuarine habitats and ecosystems.

In marine ecosystems, predator-prey interactions are known to structure critical processes (e.g., trophic transfer, nutrient regeneration) and have important implications for mediating community dynamics. However, the temporal and spatial scales over which these processes operate remain poorly understood mainly because the resolution provided by traditional sampling techniques is low. In particular, tides and physical forcing pose challenges due to sampling dynamics in coastal ecosystems. Examining the fine-scale temporal and spatial dynamics of predators and prey in tidally driven estuarine ecosystems requires implementing techniques that are robust to these challenges. Here, we examine data from a high-resolution multibeam imaging sonar (DIDSON) at the confluence of an intertidal and subtidal creek over six ebb-flood cycles and quantify the temporal and spatial scales of variance between the density of predators and prey. Densities of both groups were strongly and inversely related to tidal stage, irrespective of time of day. The potential for an encounter between functional groups and utilization of the estuarine intertidal-subtidal complex was mediated by the tidal stage. When the intertidal creek was flooded, both predator and prey fishes occupied the channel more than the slopes adjacent to the marsh edge. In addition, our study demonstrated fine-scale asynchronous timing in the distribution of predators and prey, with prey densities generally peaking prior to those of predators. This suggests that the scale of variation of prey occupying the intertidal creek, which is often thought to provide refuge, drives coincidental utilization by predators and mediates their interactions.

The extensive use of salt marsh creeks by nekton is widely recognized, yet few investigations have quantified the extent to which tidal migratory nekton make repeated visits to the same location within creek networks. An improved understanding of nekton movements and fidelity can improve insights into the nursery function and value of creek habitats. We conducted tag-recapture experiments with young fishes to determine movements among intertidal creeks in the North Inlet estuary, South Carolina. In 2008, 3246 fishes were tagged with coded microwire tags. In 2012, 577 fishes were tagged with passive integrated transponder (PIT) tags. Based on percentages of recaptures, creek-specific fidelity was determined for spot ( Leiostomus xanthurus ) (78%), silver perch ( Bairdiella chrysoura ) (71%), pinfish ( Lagodon rhomboides ) (80%), and mullets ( Mugil curema and Mugil cephalus ) (77%). Recaptures occurred up to 79 days after release. Rates of recapture of all tagged fishes combined varied among creeks (74% to 100%). Considering earlier research that demonstrated differences in habitat quality among local intertidal creeks, we suggest that differences in fidelity reflect differences in habitat quality among creeks. Greater rates of repeated use (higher fidelity) could help explain why some creeks consistently support more tidal migratory nekton than other creeks. Changes in the strength of fidelity over time could be a useful measure of changes in habitat quality. We suggest that site fidelity be considered as another metric to use in efforts by resource managers to identify and evaluate essential fish habitat.

Patterns of nekton occurrence on the salt marsh surface at high tide and in an adjacent intertidal creek pool at low tide were used to investigate movements of nekton in an intertidal basin. Paired collections were made in North Inlet estuary, SC on 67 dates over 9 years. Comparisons of high- and low-tide total abundance indicated that what remained in the creek pool at low tide was representative of the nekton on the flooded marsh. Of the 64 taxa collected, the same 8 species ranked in the top 10 in both the high- and low-tide collections. Abundances of most resident species were positively correlated with the area of marsh flooded, but mummichog (Fundulus heteroclitus), the most abundant resident, was not. Abundances of young-of-the-year transient species were not related to the extent of tidal flooding. Some transient species used the flooded marsh but did not occupy the pool at low tide, and others found in the pool did not use the marsh. Differences in abundance, biomass, and length between the marsh and pool collections indicated differences in the tendency of species and life stages to retreat downstream of the pool to the subtidal channel. Proportionately more of the nekton that were present on the flooded marsh left the intertidal basin when large changes in temperature and salinity occurred between high and low tides. More transients left the basin following higher tides, but more residents did not. The results demonstrate a wide range of taxonomic and ontogenetic patterns among nekton using intertidal salt marsh basins and the underappreciated importance of intertidal creek pools as alternative low-tide refuges.

Animals can be important in modulating ecosystem-level nutrient cycling, although their importance varies greatly among species and ecosystems. Nutrient cycling rates of individual animals represent valuable data for testing the predictions of important frameworks such as the Metabolic Theory of Ecology (MTE) and ecological stoichiometry (ES). They also represent an important set of functional traits that may reflect both environmental and phylogenetic influences. Over the past two decades, studies of animal-mediated nutrient cycling have increased dramatically, especially in aquatic ecosystems. Here we present a global compilation of aquatic animal nutrient excretion rates. The dataset includes 10,534 observations from freshwater and marine animals of N and/or P excretion rates. These observations represent 491 species, including most aquatic phyla. Coverage varies greatly among phyla and other taxonomic levels. The dataset includes information on animal body size, ambient temperature, taxonomic affiliations, and animal body N:P. This data set was used to test predictions of MTE and ES, as described in Vanni and McIntyre (2016; Ecology DOI: 10.1002/ecy.1582).

Cultured naked goby (Gobiosoma bosc) and striped blenny (Chasmodes bosquianus) larvae were used to compare life history parameters for early and late periods within a long spawning season during which temperature increased by approximately 10 °C. Hatch lengths, growth rates, larval period duration, settlement length, survivorship, and other metrics of these serial spawners were determined for larvae hatched during early and late time periods with ambient average weekly water temperatures of 20.8 (standard deviation ±2.1 °C) and 29.0 (±1.0), respectively. Cultured fishes provided parameter estimates in the absence of predation mortality and with constant prey availability. Four hypotheses were tested for each species: 1) total length at hatch is not related to temperature, 2) pelagic larval period (PLD) is negatively related to temperature, 3) growth rates and survivorship are positively related to temperature, and 4) flexion and settlement lengths are negatively related to temperature. For both gobies and blennies, hatch length decreased with increasing temperature, but was not significantly related to survivorship. Larval blennies retained the yolk-sac longer than gobies. At higher temperatures, striped blenny flexion length, settlement length, PLD, and instantaneous mortality significantly decreased while instantaneous growth in length increased. Naked goby flexion lengths, settlement lengths, PLD, and mortality rates also declined with increasing water temperatures while instantaneous growth rates increased with increasing water temperatures. Average growth in length did not change significantly with temperature for either species. Survivorship in both fishes was lowest during 0 to 6 days post hatch (dph) coincident with the yolk-sac and first feeding stages. Survivorship significantly increased with larval fish total length and age (dph) for both species and time periods. Average estimated striped blenny percentage survival increased by an order of magnitude (~3 to ~32 %) with increasing temperature while average naked goby percentage survival increased from ~3 % (early) to ~11 % (late) over the 8.3 °C temperature range examined. The observed life history parameter variation with seasonal temperature changes likely function to ensure survival to settlement for at least some cohorts within a year class as part of a bet-hedging life history strategy. Data from cultured fishes provide a baseline for future evaluation of demographics and rates from field collections.

Tidally driven fluctuations lead to rapid variations in hydrological properties that can have profound effects on the dynamic and functions of salt marshes. During low tides, many nektonic species find refuge from predatory fish in shallow intertidal pools. The utilization of shallow pool refuges also exposes fishes to fitness costs that fluctuate between day and night. Yet, how aggregated fish using an intertidal pool modulate their schooling behavior over the diel cycle remains unknown. Using high-resolution imaging sonar (ARIS), we monitored an intertidal pool over a 3-day period and quantified fish abundance, size, and schooling behavior relative to the diel and tidal cycles. Higher fish abundance was found during low tides than high tides when the section was connected with the subtidal waters. At low tide, no differences in fish abundance and size were detected in the pool between day and night, but larger schools formed at night than day. Our results suggest that biotic and abiotic factors affecting fish schooling behavior in the low tide refuge may vary over the diel cycle. We present possible functional explanations for the shifts in schooling tendency between nocturnal and diurnal utilization of the pool.

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 3h 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.

Grass shrimp are abundant residents of shallow-water habitats in US Atlantic and Gulf coast estuaries. Mark-recapture events determined the extent and direction of their movements in meso-tidal salt marsh creeks at North Inlet, South Carolina. Microwire-tagged Palaemonetes vulgaris demonstrated high fidelity for a dock in a subtidal channel. In the 48 days following release, 11 % of the 422 tagged shrimp were recaptured and 99 % of all recaptures were made there an average of 14 days post-release. Palaemonetes pugio, which favored the use of shallow intertidal areas, exhibited moderate fidelity for pools within creek beds with 53 % of the recaptured shrimp collected at the release site. Higher fidelity was observed for confluences of intertidal creeks and the subtidal channels. Of the 5565 shrimp released with coded microwire tags, 7.5 % were recaptured and 98 % of those recaptures were at release sites up to 53 days later. During another event, P. pugio released 235 m from their origin demonstrated relatively low fidelity for the new site and a lack of homing behavior. Of the 544 tagged shrimp, 3 % were recaptured; only 40 % of those recaptured were from the release site. Site fidelity is a mechanism by which previously discovered large and consistent differences in grass shrimp use of neighboring intertidal creek basins can be sustained over weeks, seasons, and years. Spatial variations and the tendency of these keystone organisms to resist relocation by tidal currents and occupy certain areas for extended periods should be considered in decisions about proposed alterations to creeks and shorelines.

A year-round survey of American eels Anguilla rostrata was performed at 5 localities in South Carolina (SC), USA, 15 yr after the first infection by the nematode Anguillicoloides crassus was reported from Winyah Bay, SC. Infections by adult stages of A. crassus in the swimbladder lumen occurred with a prevalence of 45% (n = 479), a mean intensity (± SE) of 2.3 ± 0.2 worms per infected eel (range = 1-22), and a mean abundance of 2.0 ± 0.1 among all eels. Infections by larval stages of A. crassus in the swimbladder wall occurred with a prevalence, intensity, and abundance of 29%, 2.4 ± 0.3 (range = 1-15), and 0.7 ± 0.1, respectively (n = 471). Overall prevalence of the parasite (any stage) was 58%, with a mean intensity ± SE of 3.0 ± 0.2 and a mean abundance of 1.8 ± 0.2. Biomass of the adult parasite stage varied significantly with eel body length, but the direction of the effect depended on salinity. Prevalence and intensity of infection by adult nematodes varied by locality but not by eel total length, salinity, or season. Larval prevalence was significantly greater in the winter and spring and also differed among localities. The lack of seasonal effects on infection by the adult worm stage contrasts with studies from higher latitudes in North America and Europe and may be due to the warmer winter temperatures at southern latitudes. Significant variation in infection among localities reflects possible differences in abundance of intermediate and/or paratenic hosts. Overall, infection levels were higher than previous reports for eels in SC but comparable to more recent reports from other areas in North America.

Intertidal creeks are shallow, photic ecosystems that potentially serve as sources of prey for many predators within estuaries. In a previous study, the link between nekton community structure and hydrogeomorphological variables for eight intertidal creeks was assessed for North Inlet estuary, South Carolina. Herein, we advance their findings through ecological network analysis of foodweb structure within two creeks and infer nekton trophic relationships to geomorphology and potential influences of hydrological condition and change. A summer network of a shallow, wide creek demonstrated greater carbon recycling, trophic efficiency and flow through consumers than that of a deep, narrow creek representing the same period. We infer greater export of nekton carbon from the former creek. These results were supported by analyses of nekton effective trophic levels and guilds across the eight creeks. Shallow, wide intertidal creeks appear to provide both physical and foodweb attributes that promote good nekton habitat relative to deeper and narrower creeks. Human alterations to flow regimes and sea-level rise have the ability to affect geomorphology of individual creeks and the landscape as a whole. These changes in turn have the potential to alter food webs of intertidal creeks and their ability to serve as sources of food for the larger estuary.

are critical to the vitality of estuaries and coastal waters. In this revised edition of Johnson and Allen's instant classic, readers are taken on a tour of the miniature universe of zooplankton, including early developmental stages of familiar and diverse shrimps, crabs, and fishes. Zooplankton of the Atlantic and Gulf Coasts details the behavior, morphology, and coloration of these tiny aquatic animals. Precise descriptions and labeled illustrations of hundreds of the most commonly encountered species provide readers with the best source available for identifying zooplankton. Inside the second edition: an updated introduction that orients readers to the diversity, habitats, environmental responses, collection, history, and ecological roles of zooplankton; descriptions of life cycles; illustrations (including 88 new drawings) that identify 340-plus taxa and life stages; range, habits, and ecology for each entry located directly opposite the illustration; appendices with information on collection and observation techniques and citations of more than 1,300 scientific articles and books

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.