A fauna de hidroides bentônicos do infralitoral raso, de seis locais do município de Bombinhas (Santa Catarina, Brasil), foi pesquisada e analisada com base na morfologia. O cnidoma foi examinado quando necessário para a identificação específica. Foram encontradas 25 espécies, das quais cinco (20%) são registradas pela primeira vez para o estado de Santa Catarina e três (12%) são registradas pela primeira vez para a região sul do Brasil. Houve um acréscimo de 12% e 5,5% nos registros de espécies de hidroides para Santa Catarina e litoral sul brasileiro, respectivamente.

The benthic hydroid fauna from shallow subtidal zone of six localities in the municipality of Bombinhas (state of Santa Catarina, Brazil) was surveyed and its morphology analysed. Cnidome was also examined when it was necessary for species identification. Twenty five morphospecies were found, from which five (20%) were recorded for the first time in Santa Catarina State and three (12%) were recorded for the first time in the south region of Brazil. There was a 12% and 5.5% increase in the records of benthic hydroid species for Santa Catarina and southern Brazilian coast, respectively.

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).

Decapod crustaceans from rocky shore at Farol Isle, Matinhos, Paraná, Brazil. II. Spatial distribution of population densities. A study of the spatial distribution of the decapod populations from a rocky shore at Farol Isle, Matinhos, State of Paraná, Brazil (25º51'S, 48º32'W) was canied out. In the supralittoral the rocky surface is covered partially by a layer of litter coming from the terrestrial habitats; in the midlittoral boulders and pebbles cover the rocky basin and in the infralittoral, there is a belt of seaweeds. A total of 8 samples were taken by hand, two from each of the following levels: supralittoral (emersion time 8-12 hours), upper midlittoral (4-8), lower midlittoral (0-4) and limit between midlittoral and infralittoral, monthly, from May/1990 to April/1991. The number of species increased from supralittoral (5) to infralittoral (22) and a clear vertical zonation on density was observed according to the emersion time gradient. The supralittoral is characterized by grapsids Armases angustipes (Dana, (1852), Cyclograpsus integer H. Milne Edwards, 1837 and Metasesarma rubripes (Rathbun, 1897) which have terrestrial habits and aerial respiration as a main way in obtaining the oxygen. In the midlittoral, the decapods show three basic types of adaptation against emersion desiccation and thermal stresses: (1) by digging into wet mud among the stones such as Panopeus americanus Saussure, 1857, Panopeus occidentalis Saussure, 1857 and Eurypanopeus abbreviatus Stimpson, 1860, (2) by resting in shady and wet space between the boulders and pebbles or underside of them, like Pachygrapsus transversus (Gibbes, 1850), Petrolisthes armatus (Gibbes, 1850) and adults of Menippe nodifrons Stimpson, 1859 and (3) by clinging over the soaked filamentous algae layer on the pebbles or bouders surfaces, a strategy observed in small species such as Pilumnus dasypodus Kingsley, 1879, Podochela sp., Petrolisthes galathinus (Bosc, 1801 ), Alpheus bouvieri A. Milne Edwards, 1878 and juveniles of Menippe nodifrons. In the infralittoral, small species which are vulnerable to desiccation stresses share space by diversification of their diet and adaptation strategies such as camouflage, body color change according to the substratum, flattened body for tight adhesion on hard surface and rapid movements. The main species of this zone are Petrolisthes armatus, Petrolisthes galathinus, juveniles of Menippe nodifrons, Epialtus brasiliensis Dana, 1852, P. dasypodus, Synalpheus fritzmuelleri Coutière, 1909, Megalobrachium roseum (Rathbun, 1900) and species of Palaemonidae. The rocky shore at Farol Isle is a complex architectural environment due to the conjunction of diversified habitats such as litter over a hard surface, spaces and crevices among boulders and pebbles, muddy substratum and phytal.

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.