Lengthweight relationship and parameters of growth for the checkered puffer Sphoeroides testudineus from a karstic tropical coastal lagoon: La Carbonera, Yucatan, Mexico

Summary This study reports length-weight relationships and growth parameters for Sphoeorides testudineus from La Carbonera, a karstic tropical coastal lagoon on the northwestern coast of the Yucatan Peninsula, Mexico. A total of 461 specimens were collected between April 2009 and March 2010. The lengthweight relationship was W = 0.061Lt 2.98 . Model parameters of the von Bertalanffy growth equation were: L ∞ = 29.50 cm, k = 0.77 year À1 and t 0 = À0.168 years. Introduction Sphoeroides testudineus, a member of the Tetraodontidae family, is known colloquially as checkered puffer and locally as 'xpu' (Mayan) and 'pez globo' (Spanish). It is an important estuarine-dependent fish species of ecological and commercial importance. The checkered puffer is the dominant species in many Yucatan coastal lagoons (Arceo-Carranza and Vega-Cendejas, 2009). The aim of this study was to present the LWR and to estimate the parameters of growth of S. testudineus from La Carbonera lagoon in northwestern Yucatan Peninsula. Materials and methods Samples of S. testudineus were collected during daytime between April 2009 and March 2010 in La Carbonera lagoon, a karstic coastal lagoon in northwestern Yucatan Peninsula, Mexico (21°13′-21°14′N; 89°52′-89°54′W). Collected specimens were euthanized in ice slurry, preserved in formaldehyde (4%) and transported to the laboratory where they were measured (±0.1 mm) and weighed (±0.01 g). The collected fishes were classified under three climatic seasons representing dry (March-June), rainy (July-October), and when there were prevailing north winds (NovemberFebruary). To determine parameters a and b, a regression analysis of log-converted total weight and total length was used. The 95% confidence intervals for b (CI 95%) were calculated to determine if the hypothetical value of isometry (3) fell between these intervals ÀkðtÀt0Þ , where Lt is the length at age t, L ∞ is asymptotic length, k is the growth rate (year À1 ) and t 0 is the hypothetical age of fish at length zero. The growth performance index (u') proposed by Results and discussion From a total of 461 of S. testudineus collected during the study period, 33.8% were collected in the dry season, 30.2% in the rainy season and 36% during the season when north winds prevaile

Feeding habits of the spotted rose snapper Lutjanus guttatus (Pisces: Lutjanidae) in the coast of Guerrero, Mexico

 Stomach contents analysis was used to describe quantitatively the feeding habits of Lutjanus guttatus. A total of 239 organisms with fork lengths between 12 and 55 cm were collected monthly from February 1993 to January 1995 in the coast of Guerrero. This species consumed a wide variety of prey organisms, mainly small fishes (index of relative importance, IIR = 67.46%) of the families Engraulidae, Clupeidae and Bregmacerotidae. Crustaceans, represented by Reptantia, Natantia and Stomatopoda, were consumed less (IIR = 30.94%). The composition of the diet varied as a function of the fish size. Seasonal and sexual differences in the diet were not significant

Feeding behavior and dietary composition of the northern anchovy, Engraulis mordax Girard (Pisces: Engraulidae), off Baja California, Mexico

Feeding behavior and dietary composition of northern anchovy, Engraulis mordax, off the west coast of Baja California are analyzed. The visual field for prey detection is 104 mm and the basal area of the vision cone is 125 cm2. The mean number of gill rakers in the first lower branchial arch is 41; gill raker gap increases as fish grows. Diatoms, anchovy eggs, crustaceans, dinoflagellates and protozoans are the major by-number contributors to the diet of E. mordax. Filtering mechanism acts over a 0.05 to 1.50 mm range of prey length, while selective particulate feeding occurs from 1.51 to 5.00 mm prey size spectrum. The morphometric relationship between intestine length and fish length is expressed by potential functions, and the number of curvatures varies as fish grows. Although phytoplankton is the principal by-number component of the stomach contents, zooplankton prey are consistently the major source of carbon in the diet. Prey size increases as predator grows

Effects of hurricanes on the stability of reef-associated landscapes

The effects of Hurricane Emily (July 2005, Category 4) on nine different benthic substrates in the reef-associated landscape along the west coast of Cozumel (Mexico) were evaluated by comparing the cover of nine types of substrate on ground-truthed sites before (ten months) and after (two months) the hurricane. Four substrates showed significant differences (Wilcoxon signed-rank test, P < 0.05). Coverage of sand and sand over rock increased, while that of seagrass and hard corals decreased. The effects of the hurricane on soft corals diminished below 10 m depth. Sites between 0.5 and 5.5 m were less affected towards the southwest of the island, where the reefs are more developed. Algal cover was similar to pre-hurricane values after two months, which suggests fast algal recolonization. Cozumel reefs are considered to be healthy; however, a possible increase in the abundance of macroalgae as a result of hurricanes coupled with poorly regulated tourism activities could eventually favor a phase shift in the system.

Feeding habits of the fishes Lujanus peru and Lujanus guttatus (Pisces : Lutjanidae) of Guerrero, Mexico

Feeding habits of the fishes Lutjanus peru and Lu janus guttatus (Pisces: Lutjanidae) of Guerrero, Mexico. Diet composition of the Pacific snapper (Lu janus peru) 130-684 mm fork length (FL) and the spotted snapper (Lu janus guttatus) 120-550 mm FL, was analyzed. Monthly samples were obtained from commercial landings in three regions off the coast of Guerrero, Mexico. Percentage by number (%N), percentage by weight (%W), and percentage of occurrence (%O) were calculated for each prey and summarized as the index of relative importance. Both species are polyphagous predators feeding on a variety of prey: Sixty-eight prey items, mainly fish (%W = 50.9), crustaceans (%W = 35.6), and mollusks (%W = 7.2), were found in the stomach contents of L. peru, while 88 components were identified in the diet of L. guttatus, the most important prey being fish (%W = 50.8) and crustaceans (%W = 43.4). Diet overlap between species is not significant (p < 0.05), indicating that competition for food is unlikely. Based on published values of the relative importance index, the diets of these Lutjanidae were analyzed considering different regions of the Pacific coast of Mexico and Costa Rica, and similarities among sites and species were discussed. The cluster analysis showed that similarities among species inhabiting in the same area are more important than within organisms of the same species living in different zones. Results suggest that prey availability rather than food selectivity, conditions the feeding behavior of these fish species

Coexistence of Lutjanus peru and Lutjanus guttatus (Pisces : Lutjanidae) in the coast of Guerrero, Mexico: association with the temporal variation of recruitment

Monthly volumes of capture of Lutjanus peru and Lutjanus guttatus from the coast of Guerrero, Mexico, were analyzed considering eight annual cycles. Time-series, auto correlation, and cross-correlation analysis showed that monthly abundance of populations display unsystematic variations. The FiSAT software was used to obtain the recruitment patterns of both species, using length-frequency data. Our results support the hypothesis that temporal phase-shifts in reproductive events, hence recruitment, explain the coexistence of these species. The outcome of this mechanism is a temporal succession of specific recruit abundance off the coasts of Guerrero, Mexico. The uncoupling of the recruitment events between these species, induces a separation of recruits: therefore, the intake of a particular set of preys could take place at different times

Natural feeding of juveniles of Lutjanus peru (Nichols and Murphy, 1922) (Lutjanidae: perciformes) off the coast of Jalisco and Colima, Mexico

Natural feeding of juveniles of Lutjanus peru off the coast of Jalisco and Colima, Mexico, is analyzed. A total of 915 organisms were caught; 696 stomachs were examined and 219 were discarded because they were empty. Items in the stomach content were identified to the lowest possible taxonomic level. Numeric percentage, gravimetric percentage, frequency of occurrence and the index of relative importance were calculated for each prey. The diet of the organisms studied comprises mainly fish and stomatopods, of which members of the family Congridae and organisms of Squilla hancocki are the most abundant in the stomach content. Feeding variations occurred during the year and the diet varied with respect to fish length. A significant positive correlation between the length of the crustaceans consumed and fish length was found. Differences between fish length and prey length were further verified with the Kruskal-Wallis test. Distribution of L. peru juveniles was mostly restricted to the 20- and 40-m isobaths. Low values of abundance were found at 60 m. Diet overlap between months is more frequent when prey number is considered

Feeding behavior of the hawaiian anchovy Encrasicholina purpurea fowler (Pisces: Engraulidae) in Kaneohe bay hawaii

In this paper, data on growth of the encephalon, sense organs and other feeding-related structures in Encrasicholina purpurea are analyzed. Allometric indexes of length of the different parts of the encephalon in relation to standard length (SL) were obtained. Growth of ocular lenses is isometric in organisms less than 25 mm SL, whereas positive allometric values were obtained for individuals 25+ mm SL. Growth of pectoral fins showed a similar pattern. During the life history of this species, visual perception is more important than olfactory sense for prey detection. Only larvae display tilter-feeding, while adults feed through deglutition and biting

Natural feeding of juveniles of Lutjanus peru (Nichols and Murphy, 1922) (Lutjanidae: perciformes) off the coast of Jalisco and Colima, Mexico

Natural feeding of juveniles of Lutjanus peru off the coast of Jalisco and Colima, Mexico, is analyzed. A total of 915 organisms were caught; 696 stomachs were examined and 219 were discarded because they were empty. Items in the stomach content were identified to the lowest possible taxonomic level. Numeric percentage, gravimetric percentage, frequency of occurrence and the index of relative importance were calculated for each prey. The diet of the organisms studied comprises mainly fish and stomatopods, of which members of the family Congridae and organisms of Squilla hancocki are the most abundant in the stomach content. Feeding variations occurred during the year and the diet varied with respect to fish length. A significant positive correlation between the length of the crustaceans consumed and fish length was found. Differences between fish length and prey length were further verified with the Kruskal-Wallis test. Distribution of L. peru juveniles was mostly restricted to the 20- and 40-m isobaths. Low values of abundance were found at 60 m. Diet overlap between months is more frequent when prey number is considered

Size-selective foraging behaviour of blue crabs, Callinectes sapidus (Rathbun), when feeding on mobile prey: Active and passive components of predation

Size-selective predation by small (30-50 mm carapace width) and large (90-110 mm) Callinectes sapidus when feeding on three different size classes of Litopenaeus setiferus was investigated. Laboratory experiments using no-choice and multiple-choice designs were carried out. Active and passive components of predation were evaluated by comparing the probability of attacking (active) and capturing (passive) shrimp. Small C. sapidus consumed shrimp of all size classes in similar frequencies during multiple and no-choice experiments, and the probability of attacking and capturing shrimp of all size classes was similar. Large crabs consumed large shrimp with a significantly higher frequency during multiple than during no-choice experiments, and the probability of capturing large shrimp was significantly higher than medium and small ones. Results in the present study suggest that size-specific consumption rates of C. sapidus are mainly the result of a passive mechanism associated with the salience of shrimp to predation. However, an active component of foraging behaviour related to the decision to attack an alternative prey whilst consuming one that has already been captured, helps to explain the differences in shrimp consumption between multiple and no-choice experiments. The complex interaction between active, passive components and satiation is discussed