Mayan Cichlid Cichlasoma Urophthalmus Research Articles

Lower Lethal Temperatures for Nonnative Freshwater Fishes in Everglades National Park, Florida

AbstractTemperature is an important factor that shapes biogeography and species composition. In southern Florida, the tolerance of nonnative freshwater fishes to low temperatures is a critical factor in delineating their geographic spread. In this study, we provide empirical information on experimentally derived low‐temperature tolerance limits of Banded Cichlid Heros severus and Spotfin Spiny Eel Macrognathus siamensis, two nonnative Everglades fishes that were lacking data, and African Jewelfish Hemichromis letourneuxi and Mayan Cichlid Cichlasoma urophthalmus, species for which previous results were derived from studies with small sample sizes. We also provide a literature review summarizing the current state of knowledge of low‐temperature tolerances for all 17 nonnative freshwater fishes that have been found in Everglades National Park. Mean lower lethal temperature tolerances ranged from 4°C (Orinoco Sailfin Catfish Pterygoplichthys multiradiatus) to 16.1°C (Butterfly Peacock Bass Cichla ocellaris). These low‐temperature limits may inform the understanding of the ecological role or influence of nonnative fishes and may lead to potential management opportunities and applications.

First report on the occurrence of invasive black-chin tilapia Sarotherodon melanotheron (Ruppell, 1852) in Manila Bay and of Mayan cichlid Cichlasoma urophthalmus (Gunther, 1892) in the Philippines

We report the presence of blackchin tilapia, Sarotherodon melanotheron, in the coastal waters of Manila Bay and in the river tributary of Hagonoy, Bulacan, suggesting its possible range expansion. The occurrence of the native Central American Mayan cichlid, Cichlosoma urophthalmus, is also putatively confirmed for the first time in Hagonoy, Bulacan. While morphological features, morphometric characters, and meristic counts of the current populations match those reported elsewhere for these species, further genetic work is required to confirm their identification and possibly provide information on their source. Negative impacts of the existence of the two species due to competitive interactions have already been anecdotally reported, however, no empirical scientific evidence is available to provide verification. Therefore, studies on the potential ecological impacts should be done, especially because the two species were already reported as notoriously invasive.

Experimental Infection of the Mayan Cichlid Cichlasoma urophthalmus with the Oomycete Aphanomyces invadans.

This study aimed to determine the susceptibility of the Mayan cichlid Cichlasoma urophthalmus to infection with the fungus Aphanomyces invadans (also known as epizootic ulcerative syndrome [EUS]). A total of 27 C. urophthalmus were exposed to the original A. Invadans 2006/86/EC strain by intramuscularly injecting the fish with 25,000 zoospores/ml or exposing the fish to a suspension of 25,000 zoospores/ml in 6-L aquaria for 30 days. To assess the infectious capacity of A. invadans, 3 golden barbs (Puntius semifasciolatus) were infected intramuscularly with 200,000 zoospores/ml. A second experiment using 100 C. urophthalmus was performed for 60 days with 50 fish in each treatment group. A polymerase chain reaction (PCR)-based diagnostic method was used; muscle and gills were the target tissues. In the first experiment, none of the exposed C. urophthalmus developed skin lesions related to A. invadans infection. However, PCR analysis revealed that infection had occurred. For the intramuscular treatment, there were significant differences between the controls and the muscle samples (Fisher's exact test; P < 0.05) but not between the controls and the gill samples (P > 0.05). All golden barbs became infected, as indicated by PCR, and developed skin lesions typical of A. invadans infection. We concluded that C. urophthalmus was infected with A. invadans but was an asymptomatic carrier because skin lesions did not develop. In the second experiment, all fish were negative, suggesting that the fish had cleared the infection by the end of the experiment.

Modeling the Relationship between Environmental Temperature and Feeding Performance in Florida (USA) Nonnative Fishes, with Implications for Invasive-Species Response to Climate Change

Aims: To determine the effect of environmental temperature on the feeding kinematics of two Florida (USA) invasive-fish species, pike killifish Belonesox belizanus and Mayan cichlid Cichlasoma urophthalmus, in an attempt to explore the adaptive response of wholeorganism performance to climate change. Study Design: Model I (Fixed-Effects Model) Linear Regression Analysis, y-Dependent Variable = Kinematics; x-Independent Variable = Environmental Temperature. Place and Duration of Study: Fish Ecophysiology Laboratory, Department of Biological Sciences, Florida Institute of Technology in May-December, 2011. Methodology: Four each of B. belizanus and C. urophthalmus, collected from invasive populations in Florida were acclimated in 38 liter experimental aquarium, trained, and filmed using high-speed video while eating fish-prey at 20°C, 25°C and 30°C. Four films per invasive-fish species at each temperature were analyzed using MaxTRAQ digitizing software. In each film, three kinematic-excursion (peak gape, peak hyoid depression and cranial elevation at peak gape) and three kinematic-timing (time to peak gape, hyoid depression, and cranial elevation) variables were measured. Each kinematic variable was regressed against temperature to model the relationship between feeding performance and Research Article Annual Research & Review in Biology, 4(1): 121-132, 2014 122 environmental temperature. Results: All experimental fishes behaved normally and fed aggressively in each of the three experimental temperature regimes. It is evident in the feeding kinematics-temperature plots that fish-feeding at each temperature was variable and unpredictable. Out of the 12 regression equations generated to model the relationship between feeding kinematics and environmental temperature, only one (peak gape in C. urophthalmus) showed a significant slope (Peak Gape = 1.42 + 0.01 Temperature; R = 0.22; P< 0.01). Conclusion: The models defining the relationship between feeding kinematics and environmental temperature are weak, as indicated by the extremely low values of the coefficient of determination (R). Empirical evidence indicates that the feeding performance of invasive B. belizanus and C. urophthalmus is not affected by temperature.

Partial characterisation of digestive proteases of the Mayan cichlid Cichlasoma urophthalmus

The characterisation of digestive proteases in native freshwater fish such as the Mayan cichlid Cichlasoma urophthalmus provides scientific elements that may be used to design balanced feed that matches with the digestive capacity of the fish. The purpose of this study was to characterise the digestive proteases, including the effect of the pH and the temperature on enzyme activity and stability, as well as the effect of inhibitors using multienzymatic extracts of the stomach and intestine of C. urophthalmus juveniles. Results showed that the optimum activities of the acid and alkaline proteases occurred at pH values of 3 and 9, respectively, whereas their optimum temperatures were 55 and 65 °C, respectively. The acid proteases were most stable at pH values of 2–3 and at temperatures of 35–45 °C, whereas the alkaline proteases were most stable at pH values of 6–9 and at 25–55 °C. The inhibition assays recorded a residual activity of 4% with pepstatin A for the acid proteases. The inhibition of the alkaline proteases was greater than 80% with TPCK, TLCK, EDTA and ovalbumin, and of 60 and 43.8% with PMSF and SBT1, respectively. The results obtained in this study make it possible to state that C. urophthalmus has a sufficiently complete digestive enzyme machinery to degrade food items characteristic of an omnivorous fish species, although specimens showed a tendency to carnivory.

Morphological and molecular evidences for the existence of two new species of Homalometron (Digenea: Apocreadiidae), parasites of cichlids (Osteichthyes: Cichlidae)

Two new species of Homalometron Stafford, 1904 are described, one from the Sinaloan cichlid Cichlasoma beani (Jordan)in the upper Río Santiago basin, Northwestern Mexico, and the other one from the Mayan cichlid Cichlasoma urophthal-mus (Günther) and the Redhead cichlid Vieja synspila (Hubbs) in Southeastern Mexico and Guatemala. Homalometronoctopapillatum n. sp., from the intestine of the Sinaloan cichlid, differs from all congeners by having four pairs of oralpapillae surrounding the mouth and by having vitellaria restricted to the hindbody. In addition, this new species is onlyfound in that species of cichlid, which only occurs in river basins of Northwestern Mexico. The second species,Homalometron mesoamericanum n. sp., was considered to be conspecific with the type species, Homalometron pallidumStafford, in several published accounts on the cichlid parasite fauna of Southeastern Mexico; however, detailed morpho-logical examination of museum specimens as well as freshly collected specimens, along with a comparison through mo-lecular data with H. pallidum from its natural distribution range in North America, allowed us to confirm that thisrepresents, in fact, an undescribed species. The new species is distinguished from other congeners by the combination ofthe following characters: lack of papillae around the mouth opening, the anterior extension of the vitellaria (up to the an-terior border of ovary), two compact eyespots next to pharynx and a large size (1,30–3,19). In this paper we followed anintegrative taxonomy approach in which morphological characters are used in combination with data on two nuclear ribo-somal markers (sequence divergence values and phylogenetic analysis), as well as data on host association and geographic distribution, to give further support to the recognition and description of two new species.

Development of digestive enzymes in larvae of Mayan cichlid Cichlasoma urophthalmus

The development of digestive enzymes during the early ontogeny of the Mayan cichlid (Cichlasoma urophthalmus) was studied using biochemical and electrophoretic techniques. From yolk absorption (6days after hatching: dah), larvae were fed Artemia nauplii until 15dah, afterward they were fed with commercial microparticulated trout food (45% protein and 16% lipids) from 16 to 60dah. Several samples were collected including yolk-sac larvae (considered as day 1 after hatching) and specimens up to 60dah. Most digestive enzymes were present from yolk absorption (5-6dah), except for the specific acid proteases activity (pepsin-like), which increase rapidly from 8dah up to 20dah. Three alkaline proteases isoforms (24.0, 24.8, 84.5kDa) were detected at 8dah using SDS-PAGE zymogram, corresponding to trypsin, chymotrypsin and probably leucine aminopeptidase enzymes, and only one isoform was detected (relative electromobility, Rf=0.54) for acid proteases (pepsin-like) from 3dah onwards using PAGE zymogram. We concluded that C. urophthamus is a precocious fish with a great capacity to digest all kinds of food items, including artificial diets provided from 13dah.

Salinity effects on behavioural response to hypoxia in the non‐native Mayan cichlid Cichlasoma urophthalmus from Florida Everglades wetlands

This study quantified the hypoxia tolerance of the Mayan cichlid Cichlasoma urophthalmus over a range of salinities. The species was very tolerant of hypoxia, using aquatic surface respiration (ASR) and buccal bubble holding when oxygen tensions dropped to <20 mmHg (c. 1.0 mg l(-1)) and 6 mmHg, respectively. Salinity had little effect on the hypoxia tolerance of C. urophthalmus, except that bubble holding was more frequent at the higher salinities tested. Levels of aggression were greatest at the highest salinity. The ASR thresholds of C. urophthalmus were similar to native centrarchid sunfishes from the Everglades, however, aggression levels for C. uropthalmus were markedly higher.

A New Cryptogonimid (Digenea) From the Mayan Cichlid, Cichlasoma urophthalmus (Osteichthyes: Cichlidae), in Several Localities of the Yucatán Peninsula, Mexico

Oligogonotylus mayae n.sp. is described from the intestine of the Mayan cichlid Cichlasoma urophthalmus (Günther) in Ría Lagartos, Ría Celestún, and Estero Progreso, Yucatán State. This is the second species described for Oligogonotylus Watson, 1976, the other being O.manteri Watson, 1976. The new species is readily distinguished from O. manteri by the anterior extension of the vitelline follicles. In O. Manteri, Vitelline follicles are found entirely in the hindbody, extending posteriorly to mid-testicular level. Vitelline follicles in the new species extend from teh anterior margin of posterior testis to the region between the bentral sucker and the pharynx. comparison of approximately 1,850 bases of ribosomal DNA (ITS1, ITS2, 5.8S, and 28S), and 400 bases of cytochrome c oxidase subunit I (cox1) strongly supports the status of O. mayae as a new species, as compared to O. manteri collected from cichlids in other localities of Mexico, Belize, and Guatemala.

A drop net and removable walkway used to quantitatively sample fishes over wetland surfaces in the dwarf mangroves of the southern Everglades

We describe a 9 m2 drop net and removable walkways designed to quantify densities of small fishes in wetland habitats with low to moderate vegetation density. The method permits the collection of small, quantitative, discrete samples in ecologically sensitive areas by combining rapid net deployment from fixed sites with the carefully contained use of the fish toxicant rotenone. This method requires very little contact with the substrate, causes minimal alteration to the habitat being sampled, samples small fishes in an unbiased manner, and allows for differential sampling of microhabitats within a wetland. When used in dwarf red mangrove (Rhizophora mangle) habitat in southern Everglades National Park and adjacent areas (September 1990 to March 1993), we achieved high recovery efficiencies (78–90%) for five common species <110 mm in length. We captured 20,193 individuals of 26 species. The most abundant fishes were sheepshead minnowCyprinodon variegatus, goldspotted killifishFloridichthys carpio, rainwater killifishLucania parva, sailfin mollyPoecilia latipinna, and the exotic Mayan cichlidCichlasoma urophthalmus. The 9 m2 drop net and associated removable walkways are versatile and can be used in a variety of wetland types, including both interior and coastal wetlands with either herbaceous or woody vegetation.

Effect of Salinity on the Temperature Preference and Tolerance of Age-0 Mayan Cichlids

Abstract We measured the salinity tolerance, temperature tolerance, and preferred temperature of the Mayan cichlid Cichlasoma urophthalmus to determine if temperature and salinity would limit the range expansion of this introduced species in Florida. Salinity tolerance at 25°C exceeded 37‰. The upper and lower ultimate lethal temperatures in freshwater were 39 and 15°C, respectively. Acclimation to 15‰ salinity had no effect on the lower incipient lethal temperature (15°C). Thermal preference determined in a horizontal temperature gradient was 32.8°C in freshwater, 39.2°C at 15‰, and 26.9°C at 30‰ salinity. Our results indicated that temperature and salinity are not likely to limit range expansion of the Mayan cichlid from its present location in the southern portion of the Everglades National Park, but that the species' spread may be blocked by cold winter temperatures in north Florida.