Discovering the fish fauna of a lagoon from the southeast of the Yucatan Peninsula, Mexico, using DNA barcodes.

Background: Aquatic ecosystems in the tropics are typically environments with a high species richness of fishes. These systems are also among the most vulnerable in the world, threatening the overall biodiversity of tropical regions. As a first step, it is important to enumerate the species in any ecosystem to promote its conservation. This study aims to inventory the ichthyofauna in the Chile Verde Lagoon, Quintana Roo, on the Yucatan Peninsula, a system fortunately well protected in Mexico, based on faunal surveys backed up with mtDNA barcodes. Methods: We collected larvae, juveniles, and adults of fishes in the lagoon with a variety of sampling gear targeting various life stages. Species were identified using both morphology and DNA barcodes. The abundance of species and ichthyoplankton biomass (wet weight, suction technique) were calculated from 43 samples. Results: We collected 197 adult and juvenile fishes and 3,722 larvae, of which 306 specimens were DNA-sequenced with a success rate of 96.7%. We identified 13 families, 24 genera, and 27 species in our inventory. The species number was estimated to comprise 75% of the potential total richness using the Chao 1 richness estimator. Clupeids and gobiids accounted for 87.9% of the total abundance of fishes, and, together with cyprinodontids, also accounted for the highest ichthyoplankton biomass. Conclusion: Adult and juvenile fishes were identified by morphology and meristic values, however larvae required DNA barcoding to identify species. The high biomass and abundance of larvae of clupeids, gobiids and cyprinodontids suggests that the Chile Verde Lagoon may be important for reproduction of these species in the region. Microgobius microlepis, a marine goby species, is reported for the first time in an inland oligohaline system. This study provides a basis for future environmental assessment and biomonitoring of the Chile Verde Lagoon in the Yucatan Peninsula of Mexico.

A new Cardiodectes Wilson, 1917 (Hexanauplia: Copepoda: Siphonostomatoida) parasitic on a scarid teleost (Perciformes: Scaridae) from Roatan Island, Central America.

Members of the parasitic copepod family Pennellidae are highly transformed ecto- or mesoparasites infecting a wide array of marine teleosts. Currently, this family contains more than 20 valid genera. The pennellid genus Cardiodectes Wilson, 1917 is currently known to contain 15 nominal species. Some pennellids exhibit a complex life cycle involving an intermediate host; it is known that planktonic pteropod molluscs are intermediate hosts for Cardiodectes. Pennellid mesoparasites can be detected by the conspicuous female egg-carrying trunk on the host external surface. The copepod cephalothorax is deeply embedded in the host muscle tissue. Members of Cardiodectes have been reported from several teleost families, mainly Myctophidae and Engraulidae. From the parasitological examination of a juvenile individual of a scarid teleost collected in a reef lagoon of Roatan Island, Honduras, Central America, several ovigerous female individuals of a mesoparasitic pennellid copepod were found; these specimens were recognized as representative of an undescribed species of Cardiodectes Wilson, 1917. The new species, C. roatanensis n. sp., differs from its known congeners in several respects, including the presence of neck lobes, paired posterior protuberances of the trunk, trunk shape and proportions, structure of cephalothorax lobes, cephalothorax relative size, and number of legs. The new species from Roatan is the second member of this copepod genus to be reported from the Caribbean region, after C. boxshalli Bellwood, 1981 from off Jamaica (Bellwood 1981). It is also the second report of Cardiodectes on a parrotfish.

Early life ecology of the invasive lionfish (Pterois spp.) in the western Atlantic.

The invasion of the western Atlantic by the Indo-Pacific lionfish (Pterois volitans/miles) is a serious threat to the ecological stability of the region. The early life history of the lionfish remains poorly understood despite the important role that larval supply plays reef fish population dynamics. In this study, we characterized patterns in the horizontal and vertical distributions of larval lionfish collected in the western Caribbean, US Caribbean, and the Gulf of Mexico from 19 ichthyoplankton surveys conducted from 2009-2016. Using generalized additive models (GAMs), we assessed the relative effects of spatiotemporal and environmental variation on the distribution of lionfish larvae. We also examined otoliths to determine larval ages and report the first larval growth rate estimates for this species. Lionfish larvae were present at 7.8% of all stations sampled and our model suggests that lionfish presence is related to sea surface temperature and the lunar cycle. Year and location also strongly affected the larval distribution, likely reflecting the ongoing expansion of the species during our sampling timeframe. Much of the variation in larval lionfish presence remained unexplained, and future studies should incorporate additional environmental factors to improve model predictions. This study improves our understanding of the lionfish life cycle and accentuates the need for further research into the early life history of this invasive species. The design and implementation of effective long-term lionfish control mechanisms will require an understanding of their entire life history.