Role of nearshore benthic algae in the Lake Michigan silica cycle.

Si cycling is linked with processes from global carbon sequestration to community composition and is especially important in aquatic ecosystems. Lake Michigan has seen dramatic fluctuations in dissolved silica (dSi) over several decades, which have been examined in the context of planktonic processes (diatom blooms), but the role of benthic organisms (macroalgae and their epiphytes) in Si cycling have not been explored. To assess significance of nearshore benthic algae in Si dynamics, we assembled dSi data from an offshore site sampled since the late 1980's, and sampled off three Milwaukee beaches during 2005-19. Using colorimetric assays and alkaline digestion, we measured dSi, biogenic silica in particulate suspended material (pSi) and biogenic silica in benthic macroalgae (Cladophora) and epiphytic diatoms (bSi). Offshore, dSi increased about 1 µM per year from 25 µM in the late 1980's to nearly 40 µM in 2019. Nearshore dSi fluctuated dramatically annually, from near zero to concentrations similar to offshore. Both Cladophora and its epiphytes contained significant bSi, reaching up to 30% of dry mass (300 mg Si g dry mass-1) of the assemblage in summer. Microscopic analyses including localization with a Si-specific-stain and X-ray microanalysis showed bSi in epiphytic diatom cells walls, but the nature and localization of Si in macroalgae remained unclear. A simple model was developed estimating Si demand of algae using the areal macroalgal biomass, growth rates inferred from P-content, and bSi content, and comparing Si demand with dSi available in the water column. This indicated that 7-70% of the dSi in water overlying nearshore benthic algal beds could be removed per day. Key elements of the Si cycle, including which organisms sequester bSi and how rapidly Si is recycled, remain unclear. This work has implications for coastal marine waters where large macroalgal biomass accumulates but bSi content is virtually unknown.

Using fisher-contributed secondary fins to fill critical shark-fisheries data gaps.

Developing-world shark fisheries are typically not assessed or actively managed for sustainability; one fundamental obstacle is the lack of species and size-composition catch data. We tested and implemented a new and potentially widely applicable approach for collecting these data: mandatory submission of low-value secondary fins (anal fins) from landed sharks by fishers and use of the fins to reconstruct catch species and size. Visual and low-cost genetic identification were used to determine species composition, and linear regression was applied to total length and anal fin base length for catch-size reconstruction. We tested the feasibility of this approach in Belize, first in a local proof-of-concept study and then scaling it up to the national level for the 2017-2018 shark-fishing season (1,786 fins analyzed). Sixteen species occurred in this fishery. The most common were the Caribbean reef (Carcharhinus perezi), blacktip (C. limbatus), sharpnose (Atlantic [Rhizoprionodon terraenovae] and Caribbean [R. porosus] considered as a group), and bonnethead (Sphyrna cf. tiburo). Sharpnose and bonnethead sharks were landed primarily above size at maturity, whereas Caribbean reef and blacktip sharks were primarily landed below size at maturity. Our approach proved effective in obtaining critical data for managing the shark fishery, and we suggest the tools developed as part of this program could be exported to other nations in this region and applied almost immediately if there were means to communicate with fishers and incentivize them to provide anal fins. Outside the tropical Western Atlantic, we recommend further investigation of the feasibility of sampling of secondary fins, including considerations of time, effort, and cost of species identification from these fins, what secondary fin type to use, and the means with which to communicate with fishers and incentivize participation. This program could be a model for collecting urgently needed data for developing-world shark fisheries globally. Article impact statement: Shark fins collected from fishers yield data critical to shark fisheries management in developing nations.

Uso de Aletas Secundarias Proporcionadas por Pescadores para Llenar Vacíos Importantes de Información sobre las Pesquerías de Tiburones Resumen Con frecuencia no se evalúan las pesquerías de tiburones del mundo en desarrollo ni cuentan con un manejo activo de sustentabilidad. Uno de los principales obstáculos para esto es la falta de información sobre las especies y la composición de los tamaños en las capturas. Probamos e implementamos una estrategia nueva y potencialmente aplicable en todas partes para la recolección de estos datos: la entrega obligatoria de las aletas secundarias de bajo valor económico (aletas anales) obtenidas de los tiburones desembarcados por parte de los pescadores y el uso de estas aletas para reconstruir las especies y tamaños en la captura. Usamos identificaciones genéticas de bajo costo e identificaciones visuales para determinar la composición de las especies y aplicamos una regresión lineal a la longitud total y a la de la base de la aleta anal para la reconstrucción del tamaño en captura. Probamos la viabilidad de esta estrategia en Belice, primero en un estudio de prueba de concepto y después subiendo al nivel nacional para la temporada de pesca de tiburón 2017-2018 (1,786 aletas analizadas). Se registraron 16 especies en esta pesquería. Las más comunes fueron Carcharhinus perezi, C. limbatus, Rhizoprionodon terraenovae y R. porosus (consideradas como un grupo) y Sphyrna cf. tiburo. Las últimas tres especies fueron desembarcadas principalmente por encima del tamaño maduro, mientras que con las dos primeras especies lo hacían por debajo del tamaño maduro. Nuestra estrategia demostró ser efectiva en la obtención de información crítica para el manejo de la pesquería de tiburones y sugerimos que las herramientas desarrolladas como parte de este programa puedan ser exportadas a otras naciones en esta región y aplicadas casi de manera inmediata si existen los medios para comunicarse con los pescadores e incentivarlos a proporcionar las aletas anales. Fuera del Atlántico Occidental tropical, recomendamos una mayor investigación de la viabilidad del muestreo de aletas secundarias, incluyendo la consideración del tiempo, esfuerzo y costo de la identificación de especies a partir de estas aletas; cuál tipo de aleta secundaria utilizar; y los medios mediante los cuales comunicarse con los pescadores e incentivarlos a participar. Este programa podría ser un modelo para la recolección de información de necesidad urgente para las pesquerías del mundo en desarrollo.

Multiplex real-time PCR assay to detect illegal trade of CITES-listed shark species.

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is a multilateral environmental agreement to ensure that the international trade of threatened species is either prohibited (Appendix I listed species) or being conducted legally, sustainably, and transparently (Appendix II listed species). Twelve threatened shark species exploited for their fins, meat, and other products have been listed under CITES Appendix II. Sharks are often traded in high volumes, some of their products are visually indistinguishable, and most importing/exporting nations have limited capacity to detect illicit trade and enforce the regulations. High volume shipments often must be screened after only a short period of detainment (e.g., a maximum of 24 hours), which together with costs and capacity issues have limited the use of DNA approaches to identify illicit trade. Here, we present a reliable, field-based, fast (<4 hours), and cost effective ($0.94 USD per sample) multiplex real-time PCR protocol capable of detecting nine of the twelve sharks listed under CITES in a single reaction. This approach facilitates detection of illicit trade, with positive results providing probable cause to detain shipments for more robust forensic analysis. We also provide evidence of its application in real law enforcement scenarios in Hong Kong. Adoption of this approach can help parties meet their CITES requirements, avoiding potential international trade sanctions in the future.

First insights into the movements of young-of-the-year white sharks (Carcharodon carcharias) in the western North Atlantic Ocean.

In recent years, white sharks (Carcharodon carcharias) have become more accessible to researchers off the northeastern U.S. as feeding aggregation sites have emerged and the population has increased. However, there has been limited research on young-of-the-year (YOY) sharks relative to older age classes in this region. Previous research indicated that YOY white sharks were most frequently observed in the New York Bight, suggesting the region serves a nursery role. To further examine the species' use of this area, we deployed satellite and acoustic tags on ten YOY white sharks (138-166 cm total length) off Long Island, New York. The sharks remained resident in New York Bight waters through summer (August through October), further supporting the notion that the region is a nursery area. Southward movements were observed during fall, with overwintering habitat identified off North and South Carolina shelf waters. Return migrations toward the New York Bight were observed in some individuals the following spring. YOY white sharks in this heavily-populated region are exposed to anthropogenic impacts such as fisheries bycatch and coastal habitat degradation. As juvenile survival rates are important for long-term population sustainability, further research is necessary to assess the potential impacts of these activities on the western North Atlantic white shark population.

Esophageal manometric characteristics and outcomes for laparoscopic esophageal diverticulectomy, myotomy, and partial fundoplication for epiphrenic diverticula.

PURPOSE: The purpose of this study is to characterize the esophageal motor and lower esophageal sphincter (LES) abnormalities associated with epiphrenic esophageal diverticula and analyze outcomes for laparoscopic esophageal diverticulectomy, myotomy, and partial fundoplication. METHODS: The endoscopic, radiographic, manometric, and perioperative records for patients undergoing laparoscopic esophageal diverticulectomy, anterior esophageal myotomy, and partial fundoplication from 8/99 until 9/06 were reviewed from an Institutional Review Board (IRB)-approved outcomes database. Data are given as mean +/- standard deviation (SD). RESULTS: An esophageal body motor disorder and/or LES abnormalities were present in 11 patients with epiphrenic diverticula; three patients were characterized as achalasia, one had vigorous achalasia, two had diffuse esophageal spasm, and five had a nonspecific motor disorder. Presenting symptoms included dysphagia (13/13), regurgitation (7/13), and chest pain (4/13). Three patients had previous Botox injections and three patients had esophageal dilatations. Laparoscopic epiphrenic diverticulectomy with an anterior esophageal myotomy was completed in 13 patients (M:F; 3:10) with a mean age of 67.6 +/- 4.2 years, body mass index (BMI) of 28.1 +/- 1.9 kg/m2 and American Society of Anesthesiologists (ASA) 2.2 +/- 0.1. Partial fundoplication was performed in 12/13 patients (Dor, n = 2; Toupet, n = 10). Four patients had a type I and one patient had a type III hiatal hernia requiring repair. Mean operative time was 210 +/- 15.1 min and mean length of stay (LOS) was 2.8 +/- 0.4 days. Two grade II or higher complications occurred, including one patient who was readmitted on postoperative day 4 with a leak requiring a thoracotomy. After a mean follow-up of 13.6 +/- 3.0 months (range 3-36 months), two patients complained of mild solid food dysphagia and one patient required proton pump inhibitor (PPI) for gastroesophageal reflux disease (GERD) symptoms. CONCLUSION: The majority of patients with epiphrenic esophageal diverticula have esophageal body motor disorders and/or LES abnormalities. Laparoscopic esophageal diverticulectomy and anterior esophageal myotomy with partial fundoplication is an appropriate alternative with acceptable short-term outcomes in symptomatic patients.

Clinical utility of routine barium esophagram after laparoscopic anterior esophageal myotomy for achalasia.

BACKGROUND: This study aimed to evaluate the clinical utility of routine barium esophagram after laparoscopic anterior esophageal myotomy for achalasia. METHODS: The records of 260 consecutive patients who underwent laparoscopic anterior esophageal myotomy for achalasia from May 1996 to August 2007 were reviewed from a prospective institutional review board-approved database. Data are given as mean +/- standard deviation. Statistical significance (p \ 0.05) was determined using a two-tailed t-test and Fisher's exact test. RESULTS: Routine protocol barium esophagrams performed for 236 patients a mean of 1 +/- 0.3 days postoperatively were interpreted for 145 (61.4%) of the patients as normal flow of contrast after esophageal myotomy. There were no false-negative studies in this group, and diet was initiated without incident at a mean of 1 +/- 0.2 days. The time to the goal diet was 1.3 +/- 0.7 postoperative days, and the mean postoperative time to discharge was 1.5 +/- 1 days. Of the 236 patients, 91 (38.6%) had an abnormal barium esophagram (contrast retention or pooling, delayed emptying). For this group, initiation of a diet was delayed for only six (6.6%) patients. Two barium esophagrams (0.9%) interpreted as an esophageal leak were determined to be false-positives after the one patient underwent negative exploratory laparoscopy and the other was observed clinically. In this group, diet was initiated at a mean of 1.1 +/- 0.3 days. The time to the goal diet was 1.4 +/- 0.7 days, and the mean postoperative time to discharge was 1.8 +/- 1.9 days. The mean times to diet initiation, goal diet, and discharge were not significantly different (p >or= 0.14) between the normal and the abnormal barium esophagram groups. The sensitivity and specificity of an abnormal routine barium esophagram after laparoscopic esophageal myotomy were, respectively, 100% and 62.0%, and the positive and negative predictive values were 2.2% and 100%. CONCLUSIONS: Because of its poor positive predictive value, routine barium esophagram after laparoscopic anterior esophageal myotomy should be used selectively in the immediate postoperative period after an uncomplicated procedure.

Characterization of the low-energy electronic excited states of benzoyl-substituted ruthenocenes.

Electronic absorption and resonance Raman spectral studies of benzoylruthenocene (BRc) and 1,1'-dibenzoylruthenocene (DRc) indicate that the low-energy electronic excited states of these 4d(6) metallocenes possess metal-to-ligand charge transfer (MLCT) character. While this MLCT contribution should weaken the metal-ring bonding in the excited state, neither compound is photosensitive in nonhalogenated solvents such as methanol, acetonitrile, and cyclohexane. In contrast, irradiating BRc and DRc in the good electron-accepting solvent, carbon tetrachloride, results in ring loss via a pathway that appears to originate from a charge-transfer-to-solvent excited state. Both metallocenes function as photoinitiators for the anionic polymerization of ethyl 2-cyanoacrylate, and the kinetics and mechanism of this process have been investigated. Comparing the present results on BRc and DRc with those reported earlier for the corresponding benzoyl-substituted ferrocene compounds reveals some interesting commonalities and differences between the excited-state properties of these 3d and 4d metallocenes.