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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]

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]