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Abstract The effect of individual and population-level egg mortality is important to quantify to maintain sustainable crustacean fisheries. The nemertean worm Carcinonemertes carcinophila (Kölliker, 1845) is an egg predator of the Atlantic blue crab, Callinectes sapidusRathbun, 1896; however, little is known about the impact this nemertean has on the reproduction of the blue crab. We assessed the prevalence and intensity of the infestation of nemerteans in ovigerous blue crabs using a fishery-independent trawl survey. During the primary spawning period of the crab, May–September 2022, 126 ovigerous females were collected and analyzed for worms. Prevalence over this time was 66.6% and mean brood infestation was 53.9 worms per infested crab host. Nemertean egg consumption was quantified with a six-day microcosm experiment. Of the 48 worms in the experiment, 71% actively fed on crab eggs and their consumption ranged 0.16–4.5 eggs day–1. Consumption rates were used to estimate population-level impact of nemertean feeding on crab brood mortality. Modeled proportions of brood loss per crab ranged 0–0.0044%. At the current prevalence and intensity of infestation, egg consumption by nemerteans has a negligible effect on blue crab reproductive output and batch fecundity in Chesapeake Bay. We also investigated the use of mature nemertean worms as a biomarker for establishing the spawning history of ovigerous female blue crabs and determined that the presence of worms in the clutch and in the gills can be used to indicate parity in ovigerous female crabs.
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In an effort to design deep-blue light emitting materials for use in OLEDs, the optical and electronic properties of a series of tetraarylbenzobis[1,2- d :4,5- d ′]oxazole (BBO) cruciforms were evaluated using density functional theory (DFT) and time-dependent DFT (TD-DFT). Of the nine possible combinations of phenyl-, furan-2-yl-, and thiophen-2-yl-substituted BBO cruciforms, five were predicted to have ideal optical and electronic properties for use in blue-light emitting diodes. These five cruciforms were synthesized and then characterized electrochemically and spectroscopically. Additionally, they were solution-processed into functional organic light-emitting diodes (OLED). Several of the OLEDs exhibited deep-blue EL ( λ EL < 452 nm; CIE y ≤ 0.12) with maximum luminance efficacies reaching 0.39 lm W −1 and maximum current efficiencies of 0.59 cd A −1 . A comparison of identical device architectures showed that heterocycles such as furan and thiophene helped improve device efficiencies with only a minor red-shift of the electroluminescence (EL). Although these BBO cruciforms produced the desired deep-blue emission their modest performance in host–guest OLEDs demonstrates the incorporation of heterocycles onto the BBO cruciform motif is detrimental to the fluroescence quantum yield. These results add to the knowledge base on structure–property relationships that will inform the design of better blue emitting materials.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-4357/ab2bf8
