Geology topics

Leo Nico

Publications and source records attributed to Leo Nico.

10 recordsLinked to original sources

USGS2022

Occurrence of a reproducing wild population of Channa aurolineata (Pisces: Channidae) in the Manatee River drainage, Florida

We report on the discovery of a wild, reproducing population of Channa aurolineata (Pisces: Channidae) in west-central Florida (USA), and first documented occurrence of snakeheads in the Gulf Coast region. Channa aurolineata is a large, predatory fish of the bullseye snakehead “Marulius group” species complex from Asia. Adult and juvenile specimens were captured in June 2020 in a 1.8-hectare pond that connects during high water to a small stream within the Manatee River-Tampa Bay Basin. The pond site is 250-km from the only other wild C. aurolineata population in the USA (present in southeast Florida since ca. 2000) and is considered a separate introduction and not the result of natural dispersal. Morphological and molecular comparisons revealed high overlap between the two Florida populations, evidence humans may have transported fish between sites. To verify identification, we compared Florida samples to C. aurolineata from Thailand and found mtDNA-COI barcode sequences to be identical or to differ by only a single base pair. Life body coloration of Florida samples matched their Asian counterparts, but Florida specimens averaged fewer dorsal fin rays (53.6 vs. 56.0), anal fin rays (34.2 vs 36.1), lateral line scales (65.3 vs. 67.4), and vertebrae (62.1 vs. 64.3), differences implying possible founder effect or sampling bias. Existence of this invasive predator is a concern because of the risk of spread and negative ecological effects, including an observation of terrestrial hunting behavior. In 2020–2021, several hundred C. aurolineata were removed from the pond by nets and electrofishing, and surveys suggested the population had not spread to nearby waters. In May 2021 the pond was treated with rotenone and 48 more specimens were recovered. No additional snakeheads have been sighted since the piscicide operation, although verification of eradication will require monitoring of the watershed.

Florida↗

USGS2021

Evaluating establishment success of non-native fishes introduced to inland aquatic habitats of tropical Pacific islands

An information-theoretic approach was used to evaluate non-native freshwater fish species introduced to insular habitats of Hawaii and Guam comparing successful establishments vs. failures. Since the late 1800s, as many as 81 non-native freshwater fish species have been recorded as introduced to Hawaii and Guam (combined) and 50 (62%) of these are documented as having one or more established populations. We examined eleven independent variables to investigate establishment success by creating 21 a priori logistic regression models ranked using Akaike's Information Criterion adjusted for small sample size. An additional eight post-hoc models were included that comprised the best a priori model and various combinations of individual variables. The best overall model of establishment probability included effects of taxonomic affinity (family membership), prior establishment success on other tropical islands, and hypoxia tolerance. Establishment success in Hawaii and Guam was highest for those species established on many other islands, and according to our best model air-breathing fishes were more likely to become established. Six fish families, each with from three to 18 species introduced to Pacific islands, were highly successful at establishment: Cichlidae (16 established of 18 species introduced), Poeciliidae (seven of eight), Cyprinidae (four of seven), Centrarchidae (four of four), Clariidae (three of three), and Loricariidae (three of four). Those that successfully established include both small and moderately large-bodied taxa, while representing a diverse array of other morphological and life-history traits. Pathways and motives associated with fish introductions in the Pacific have been linked to desires to develop aquaculture, enhance wild stocks of food, sport, and bait fishes, for use as biological control agents, or are linked to the ornamental fish trade. We found that many established species were introduced via multiple pathways (up to eight) and our analyses suggest that the combination of prior establishment success on other tropical islands and presence of non-native fishes in multiple pathways was indicative of high propagule pressure. Our study results and conclusions on Pacific tropical island introductions are in general agreement with previous studies on non-native freshwater fishes in other regions of the world and similar to observations in continental ecosystems and temperate zones.

Hawaii↗

USGS2020

Discovery of a reproducing wild population of the swamp eel Amphipnous cuchia (Hamilton, 1822) in North America

We report discovery of an established population of the Asian swamp eel Amphipnous cuchia (Hamilton, 1822) in Bayou St. John, an urban waterway in New Orleans, Louisiana, USA. This fish, commonly referred to as cuchia (kuchia), is a member of the family Synbranchidae and is native to southern and southeastern Asia. Recently-used synonyms include Monopterus cuchia and Ophichthys cuchia . We collected both adult and young-of-year cuchia from dense mats of littoral vegetation at several locations in Bayou St. John. Presence of multiple age and size classes is the first documented evidence of reproduction of this species outside of its native range. Establishment of this air-breathing, burrowing, salt-tolerant, opportunistic predator is of concern given that Bayou St. John is a tributary of Lake Pontchartrain, which provides a direct pathway for dispersal into the Mississippi River basin and coastal wetlands of the Gulf of Mexico.

Louisiana↗

USGS2019

Environmental DNA assays for invasive populations of the Black Carp, Mylopharyngodon piceus, in North America

The Black Carp, Mylopharyngodon piceus, is an increasingly widespread invasive species in North America that threatens freshwater mussel populations. We developed four qPCR assays for detecting environmental DNA (eDNA) from these Black Carp populations. Assays were designed to target four mitochondrial DNA loci and were based on 34 complete mitochondrial genome sequences, including 29 generated in this study from samples obtained in three countries. Assays were validated for taxon specificity with in silico comparisons against archived DNA sequences and with in vitro tests of 41 DNA samples from Black Carp, as well as DNA samples from 30 non‐target fish species, all from the Mississippi River Basin. All four assays were able to detect the DNA of all Black Carp samples and did not exhibit any positive results with DNA from other tested species. Tests conducted in round‐robin fashion among three different laboratories found that all four assays were able to detect DNA at very low template concentrations (limits of detection = 3 copies/qPCR, limits of quantification = 16‐64 copies/qPCR) and, as part of in situ validation, were successful in detecting eDNA from Black Carp in aquaculture ponds. Despite some challenges with other attempts at in situ validation, the assays were also effective in detecting Black Carp eDNA in water samples from a drainage ditch in the upper reaches of the species’ range that was known to contain juvenile Black Carp, as well as in water samples from the Missisippi River and a connected oxbow lake in the lower reaches of the species range.

Transactions of the American Fisheries Society↗

USGS2019

Asian swamp eels in North America linked to the live-food trade and prayer-release rituals

We provide a history of swamp eel (family Synbranchidae) introductions around the globe and report the first confirmed nonindigenous records of Amphipnous cuchia in the wild. The species, native to Asia, is documented from five sites in the USA: the Passaic River, New Jersey (2007), Lake Needwood, Maryland (2014), a stream in Pennsylvania (2015), the Tittabawassee River, Michigan (2017), and Meadow Lake, New York (2017). The international live-food trade constitutes the major introduction pathway, a conclusion based on: (1) United States Fish and Wildlife Service’s Law Enforcement Management Information System (LEMIS) database records revealing regular swamp eel imports from Asia since at least the mid-1990s; (2) surveys (2001–2018) documenting widespread distribution of live A. cuchia among ethnic food markets in the USA and Canada; (3) indications that food markets are the only source of live A. cuchia in North America; and (4) presence of live A. cuchia in markets close to introduction sites. Prayer release appears to be an important pathway component, whereby religious practitioners purchase live A. cuchia from markets and set them free. Prevalence of A. cuchia in US markets since 2001 indicates the species is the principal swamp eel imported, largely replacing members of the Asian complex Monopterus albus/javanensis. LEMIS records (July 1996–January 2017) document 972 shipments containing an estimated 832,897 live swamp eels entering the USA, although these data underestimate actual numbers due to undeclared and false reporting. LEMIS data reveal most imports originate in Bangladesh, Vietnam, and China. However, LEMIS wrongly identifies many imported swamp eels as “Monopterus albus”; none are identified as A. cuchia although specimens from Bangladesh and India are almost certainly this species. Some imported A. cuchia are erroneously declared on import forms as Anguilla bengalensis. To date, there is no evidence of A. cuchia reproduction in open waters of North America, presumably because it is a tropical-subtropical species and all introductions thus far have been in latitudes where winter water temperatures regularly fall near or below freezing.

Aquatic Invasions↗

USGS2017

Distribution and status of five non-native fish species in the Tampa Bay drainage (USA), a hot spot for fish introductions

The Tampa Bay region of Florida (USA) is a hot spot for non-native freshwater fishes. However, published information on most non-native fishes in the basin is not current. Systematic sampling efforts targeting non-native fishes in the region were conducted from 2013–2015 by the University of Florida Tropical Aquaculture Laboratory. Data from these recent surveys were analyzed, along with historic and new data from published and unpublished sources, to assess current fish distributions and determine status. We focus on five of the non-native species sampled: pike killifish Belonesox belizanus Kner, 1860, green swordtail Xiphophorus hellerii Heckel, 1848, southern platyfish Xiphophorus maculatus (Günther, 1866), Mayan cichlid Mayaheros urophthalmus (Günther, 1862), and Jack Dempsey Rocio octofasciata (Regan, 1903). All five were found to have reproducing populations in the basin, each showing broader distributions than previously indicated. Non-native populations of four of the species have persisted in the Tampa Bay region since at least the 1990s. In contrast, the presence of Mayan cichlid in the basin was not confirmed until 2004. Based on numbers, distributions, and years of persistence, these five species all maintain established populations. Pike killifish and Mayan cichlid are established and spreading throughout multiple habitat types, while green swordtail, southern platyfish, and Jack Dempsey are localized and found primarily in more marginal habitats (e.g., small ditches and first order tributary streams). Factors affecting continued existence and distributions likely include aquaculture, biotic resistance, and thermal and salinity tolerances. We also clarify non-native species status determination using a multi-agency collaborative approach, and reconcile differences in terminology usage and interpretation.

Florida↗

USGS2017

Serrasalmidae — Piranhas and Pacus

The family Serrasalmidae is a morphologically and ecologically diverse group of South American freshwater fishes consisting of 16 genera and about 91 valid species. This chapter is a summary of the current state of knowledge on serrasalmid taxonomy, species richness, and ecology, and provides an identification key to the genera and references to relevant literature for species-level identifications. Included is information on native and non-native populations.

Book chapter↗

USGS2016

Detection limits of quantitative and digital PCR assays and their influence in presence-absence surveys of environmental DNA

A set of universal guidelines is needed to determine the limit of detection (LOD) in PCR-based analyses of low concentration DNA. In particular, environmental DNA (eDNA) studies require sensitive and reliable methods to detect rare and cryptic species through shed genetic material in environmental samples. Current strategies for assessing detection limits of eDNA are either too stringent or subjective, possibly resulting in biased estimates of species’ presence. Here, a conservative LOD analysis grounded in analytical chemistry is proposed to correct for overestimated DNA concentrations predominantly caused by the concentration plateau, a nonlinear relationship between expected and measured DNA concentrations. We have used statistical criteria to establish formal mathematical models for both quantitative and droplet digital PCR. To assess the method, a new Grass Carp ( Ctenopharyngodon idella ) TaqMan assay was developed and tested on both PCR platforms using eDNA in water samples. The LOD adjustment reduced Grass Carp occupancy and detection estimates while increasing uncertainty – indicating that caution needs to be applied to eDNA data without LOD correction. Compared to quantitative PCR, digital PCR had higher occurrence estimates due to increased sensitivity and dilution of inhibitors at low concentrations. Without accurate LOD correction, species occurrence and detection probabilities based on eDNA estimates are prone to a source of bias that cannot be reduced by an increase in sample size or PCR replicates. Other applications also could benefit from a standardized LOD such as GMO food analysis, and forensic and clinical diagnostics.

Molecular Ecology Resources↗

USGS2015

Evaluating the piscicide rotenone as an option for eradication of invasive Mozambique tilapia in a Hawaiian brackish-water wetland complex

Mozambique tilapia Oreochromis mossambicus were recently discovered in ‘Aimakapā Fishpond, a 12-hectare brackish-water wetland complex in Kaloko-Honokōhau National Historical Park, on the Island of Hawai’i. As a possible eradication method, we evaluated rotenone, a natural piscicide used in fish management and the active ingredient in plants traditionally used by indigenous Hawaiians for capturing fish. To assess rotenone’s efficacy in killing tilapia and effects on non-target species, laboratory toxicity tests involved exposing organisms to various concentrations of liquid CFT Legumine (5% rotenone) in static trials of 48-h to 72-h duration. Test organisms included: Mozambique tilapia, non-native guppy Poecilia reticulata , the non-native odonate Rambur’s forktail Ischnura ramburii , native feeble shrimp Palaemon debilis , and native ‘ōpae’ula shrimp Halocaridina rubra . All organisms and water used in tests were obtained from ‘Aimakapā (12.6–12.7 ppt salinity), or, for H. rubra , an anchialine pool (15.0–15.2 ppt salinity). Survival analyses indicated CFT Legumine concentrations >3 ppm (>0.15 mg/L rotenone) achieved 100% mortality of tilapia and 93% of guppies within 24 h, with most tilapia killed by 6 h and most guppies by 2 h. Little or no mortality was observed among invertebrate exposed to 1 to 5 mg/L CFT Legumine: 0% mortality for ‘ōpae’ula shrimp, 4% for feeble shrimp; and 16% for odonate larvae. The 48 h LC50 values for Mozambique tilapia and guppy were 0.06 and 0.11 mg/L rotenone, respectively. Results demonstrate rotenone’s potential for non-native fish eradication in brackish-water habitats, with benefit of low mortality to certain macro-invertebrates. High rotenone tolerance displayed by ‘ōpae’ula shrimp is noteworthy. Invasive fish are common in anchialine pools, threatening existence of shrimp and other invertebrate fauna. Although rotenone’s effects on freshwater organisms have been well studied, our research represents one of only a few controlled laboratory experiments quantitatively assessing rotenone tolerance of brackish or marine fauna.

Hawaii↗

USGS2015

One carp, two carp: are there more carp in the Wailoa River?

The February, 2015 issue of Hawaii Fishing News included the annual list of Hawai`i records for the largest fish of various species caught in the state. Among the new records was one for a 15-pound grass carp (Ctenopharyngodon idella) caught by Avery Berido in the Wailoa River at Hilo on September 13, 2013. A photograph taken by Mr. Berido of the record grass carp garnered our attention because pictured fish looked quite similar to another Asian carp species, the black carp (Mylopharyngodon piceus). Mr. Berido informed us that he also captured a 10-pound grass carp from the same river in June, 2013. After close examination of all of the photographs provided by Mr. Berido, we concluded that both fish from the Wailoa River were unusually dark grass carp, not black carp.

Hawaii Fishing News↗