Estrutura populacional de Hyale media (Dana) (Amphipoda, Gammaridea, Hyalidae), habitante dos fitais de Caiobá, Matinhos, Paraná, Brasil Population structure of the seaweed dweller Hyale media (Dana) (Amphipoda, Gammaridea, Hyalidae) from Caiobá, Matinhos, Paraná, Brazil

<abstract language="eng">A study of correlation between the total body length and the somites length was carried out in a population of Hyale media (Dana, 1857), in order to know which somite or group of somites has the highest correlation index with the total body length. As the sum of the length of the first to fourth pereonites showed the highest linear correlation index (Y=0.0764+0.2736X; r=0.9723), this meristic parameter was chosen to describe the population structure of the species. The following aspects were treated: distribution of the body size classes in the various phytals, population composition, seasonal fluctuation of population density. relative frequency of the ovigerous females and correlation between the body length and the number of eggs inside the marsupium of the ovigerous females. The amphipods were obtained from the seasonal collections of six phytals from a rocky seashore of Caiobá, Paraná State: Pterosiphonia pennata (Roth) Falkenberg. Gymrogongrus griffithsiae (Turner) Martius, Pterocladia capillacea (Gmelin) Bornet & Thured, Sargassum cymosum Garth, Gelidium sp and Ulva fasciata Delile; they did not occurred in Padina gymnospora (Kútsing) Vickers and Porphyra atropurpurea (Olivi) De Toni. The air temperature oscillated from 16ºC (winter and autumn) to 23ºC (summer), the surface water temperature from 17ºC (winter) to 25ºC (summer) and the surface water salinity, from 29.3‰ (autumn) to 32.8‰ (winter). The density oi Hyale media varied from 0.20 ind.g-1 (in Ulva) to 26.37 ind.g-1 (in Pterosiphonia) of alga-substratum weigth, and the population was distributed mainly in branched algae. It was determined three size classes in the population, within a range from 0.01 to 2.99mm of pereonits 1-4 length. Small amphipods prefer finely branched algae like Gymnogongrusand Pterosiphonia, whereas broad-thallii or less branched algae such as Sargassum, Pterocladia, Gelidium and Ulva harbour proporcionally high number of large individuais. The life cycle of Hyale media takes place wholly in the phytals and the species reproduces continually all year round: males, ovigerous females and juveniles are present every season. The highest femalc reproductive activity occurs in winter and the juveniles are more numerous in summer. The number of eggs inside the marsupium and the pereonites 1-4 length has a linear correlation (Y=-9,9682+12,0729X; r=0.8024)

Ecologia populacional dos Amphipoda (Crustacea) dos fitais de Caiobá, Matinhos, Paraná, Brasil Population ecolocy of Amphipoda (Crustacea) from the phytals of Caiobá, Matinhos, Paraná, Brazil

<abstract language="eng">Spalial and temporal density distributions of Amphipoda from the phytals of Caiobá are described. Air temperature oscillated from 16ºC (August and May) to 23ºC (March), surface water temperature from 17ºC (August) to 25ºC (March) and the salinity from 29.3‰ (May) to 32.8‰ (August). Two samples of 25cm² (for algae less than 5cm long), 100 cm² (for algae between 5-10cm long) and whole plants (for algae more than 10cm long) were removed with a spatula from the rocky surface at Caiobá Beach, in August/86, November/86, March/87 and May/87. After sorting, the algal substrata were weighted, their adsorption coefficient calculated and the sediment retained among the thallii weighted. The average distance between the branching was measured for all branched algae. The densities were calculated in relation to the weight of the algal substrate in grams. Eight phytals were considered: Ulva fasciata Delile, Padina gymnospora (Kútzing) Vickers, Sargassum cymosum Garth, Porphyra atropurpurea (Olivi) De Toni, Gelidium sp., Gymnogongrus griffithsiae (Turner) Martius, Pterocladia capillacea (Gmelin) Bornet &Thurel and Pterosiphonia pennata (Roth) Falkenberg, over which nine Amphipoda species live: Ampithoe ramondi Audouin, 1816, Cymadusa filosa Savigny, 1852, Elasmopus pectenicrus Bate, 1857, Hyale media Dana, 1857, Hyale sp.l, Jassa falcata Montagu, 1895 and Sunampithoe pelagica H. Milne-Edwards, 1830 (Gammaridea). Caprella danilevskii Czerniavski, 1861 and Caprella penantis Leach, 1814 (Caprellidea). Amphipoda densities ranged from 0.27 ind.g-1 to 45.68. ind.g-1. The broad-thallii algae Porphyra, Ulva and Padina harbored lower densities of Amphipoda, whereas those finely branched Pterocladia, Pterosiphonia and Gymnogongrus, the highest values and the less branched Sargassum and Gelidium, intermediate values. The high densities found in the finely branched algae had as main contribution the juvenile recruiting of most Amphipoda. The tide level might have influenced the temporal distribution of the Amphipoda density, due to the distinct time of air exposition in eaeh collection data. Most Amphipoda did not show specific algal substratum colonization: only Sunampithoe pelagica occurred solely in Sargassum. Four species occurred in different branched algae: J. falcata. S. pelagica. C. danilevskii and C. penantis. H. media had Sargassum, Pterocladia, Pterosiphonia and Gymnogongrus as the best algal substrata, whereas Caprellidea, the Pterocladia and Pterosiphonia phytals. High sediment weight in Padina was the main reason for high densities of Hyale sp.l in this phytal. The occurrence of males, females (including ovigerous ones) and juveniles of most Amphipoda species found in the present study indicates a complete life cycle whithin these phytals and corroborates with the assumption of the complexity of this marine coastal ecosystem