ARQ - LMS - Número 23A
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Artigos publicados no Número 23A - 2006
CONTENTS:
Sjögren, E.. - Bryophytes (Musci) unexpectedly rare or absent in the Azores.Parente, M. I., A. I. Neto, R. L. Fletcher, M. C. Gil-Rodriguez & R. J. Haroun. - Morphological studies of Hapalospongidion macrocarpum and Nemoderma tingitanum (phaeophyceae) from the Salvage Islands (Madeira archipelago).
Clarke, M. R.. - Oceanic cephalopod distribution and species diversity in the eastern north Atlantic.
Vasconcelos, J., A. Alves, E. Gouveia & G. Faria. - Age and growth of the blue jack mackerel, Trachurus picturatus Bowdich, 1825 (Pisces: Teleostei) off Madeira archipelago.
Neves, V. C., N. Murdoch & R. W. Furness. - Population status and diet of the Yellow-legged Gull in the Azores.
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Wirtz, P.. - Ten invertebrates new for the marine fauna of Madeira.Browse
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- Ten invertebrates new for the marine fauna of Madeira.Publication . Wirtz, PeterThe nemertine Drepanogigas albolineatus, the gastropods Coralliophila kaofitorum, Haminoea orteai, Discodoris rosi and Janolus n sp, the decapod Palaemonella atlantica, the phoronids Phoronis australis and Phoronopsis californica, the starfish Chaetaster longipes and the tunicate Distaplia corolla are recorded from Madeira archipelago for the first time.
- Population status and diet of the Yellow-legged Gull in the Azores.Publication . Neves, Verónica C.; Murdoch, Nadia; Furness, Robert W.During 2004 a census of the Yellow-legged Gull (Larus michahellis atlantis) was conducted in the Azores to assess its present status in the archipelago. The census yielded an estimate of 4249 breeding pairs, an increase by almost 60% since the previous survey conducted in 1984. Gulls were detected on a total of 14 islets and/or sea stacks and are probably limiting the distribution of terns in the archipelago. Out of 37 gull breeding sites found during the 1984 and 2004 surveys, 24 were located within 1 km of tern colonies. All the gull colonies were coastal except Lagoa do Fogo on São Miguel Island. Pellet analysis indicated that gulls from all the colonies feed on refuse, but the percentage of pellets containing refuse on islands with small human populations was less than half than that of islands with more than 55000 inhabitants. Gulls have no direct competitors in the Azores and benefit from an increase in refuse production. The growing number and size of rubbish dumps over the last two decades has probably contributed to the large increase in the Azorean population.
- Age and growth of the blue jack mackerel, Trachurus picturatus Bowdich, 1825 (Pisces: Teleostei) off Madeira archipelago.Publication . Vasconcelos, Joana; Alves, Adriana; Gouveia, Elisabete; Faria, GraçaBetween 1984 and 1986, 630 pairs of sagitta otoliths were collected to determine the age and growth of the blue jack mackerel, Trachurus picturatus from Madeiran waters. The oldest specimen in this study was nine years old and the largest was 46 cm of total length (TL). The parameters of the von Bertalanffy growth curve were estimated for the whole period studied for all fish (L∞=42.32 cm, k=0.161 year-1, t0= -2.563 year; r2=0.743) for males (L∞=39.57 cm, k=0.194 year-1, t0=-2.282 year; r2=0.722) and for females (L∞=49.78 cm, k=0.114 year-1, t0=-3.052 year; r2 = 0.747). There was no significant differences in mean lengths (t–test, p>0,05) and in the von Bertalanffy growth curves (Ftest, p>0,05) between sexes. The validity of otolith readings for estimating age and growth was supported by results from backcalculation method. No significant differences were found in the Bertalanffy growth curves between direct reading of otoliths and backcalculation. Growth parameters estimated from backcalculated sizes-at-age were: for both sexes, L∞=48.28 cm, k=0.135 year-1, t0=-2.898 year and r2=0.999; for males, L∞=44.79 cm, k=0.143 year-1, t0=-3.207 year, r2=0.999; and females, L∞=44.63 cm, k=0.163 year-1, t0=-2.430 year, r2=0.999. The relationship between length and weight was calculated for all fish (Wt=0.00764Lt3.05746; r2=0.951), for males (Wt=0.01271Lt2.90807; r2=0.915) and for females (Wt=0.00604Lt3.12613; r2=0.948).
- Oceanic cephalopod distribution and species diversity in the eastern north Atlantic.Publication . Clarke, Malcolm R.This work provides a baseline against which we might measure future changes to oceanic midwater cephalopod stability in the eastern North Atlantic It records a considerable sampling effort from 1959 to 1986 aimed at oceanic midwater cephalopods made by the author and colleagues in the eastern North Atlantic between approximately 10ºN to 70ºN and 0ºto 30ºW. From these samples the latitudinal distribution, the biodiversity and, to some extent, the relative rarity of the species present in the area is shown. Over 700 collections were made with a range of nets from small plankton nets to large commercial trawls of many designs. As an independent measure of the efficiency of our sampling, the species represented by lower beaks from the stomach contents of 241 sperm whales (Physeter catodon) caught or stranded at five different localities in the area are listed and discussed. In total, over 40,000 cephalopods of 82 oceanic midwater species and 16 shelf and slope species were identified and are included here. The number of midwater species caught by nets increases regularly from 11ºN to 32ºN and decreases from 32ºN to 60ºN. A sharp increase at 32ºN of about 10 species above the curve produced by the catches at other stations is very probably due to the use of lights on the nets at this position. This suggests that further use of lights at all stations might elevate the curve at each position commensurate with the numbers of species found by conventional nets. The number of midwater cephalopods caught by nets in each of the 32 families show that Cranchiidae are by far the most numerous (and speciose) followed by Pyroteuthidae and Enoploteuthidae at half the number. 18 families numbered less than 100 individuals. Families eaten by sperm whales showed that Histioteuthidae was by far the most numerous (22787) with Cranchiidae (3285), Octopoteuthidae (1710) and Cycloteuthidae (1360) following in importance. Architeuthidae was not caught by nets but was present in the whale diet (221). The scarcity and expense of net collections suggests that estimates of cephalopod distribution and relative numbers should rely more on analysis of the diet of predators than on net catches. The value of monitoring cephalopods in the deep ocean is discussed.
- Morphological studies of Hapalospongidion macrocarpum and Nemoderma tingitanum (phaeophyceae) from the Salvage Islands (Madeira archipelago).Publication . Parente, Manuela I.; Neto, Ana I.; Fletcher, Robert L.; Gil-Rodríguez, María C.; Haroun, Ricardo J.Two species of encrusting brown algae (Phaeophyceae) are newly recorded for the Salvage Islands (Madeira Archipelago) viz. Nemoderma tingitanum and Hapalospongidion macrocarpum. The species are described, and information is presented concerning their ecology, morphology and geographical distribution in the Atlantic.
- Bryophytes (Musci) unexpectedly rare or absent in the Azores.Publication . Sjögren, ErikSearch for bryophytes in the Azores has until now resulted in a recording of about 430 species of mosses and hepatics. A few of these species are endemic to the Azores or to the Macaronesian island groups. The majority of the other species includes cosmopolitan or oceanic/suboceanic European species. This paper treats some mosses (Musci) which have not managed to get established in the Azorean bryovegetation. Some are just unexpectedly rare and frequently recorded as present in only one or two of the nine Azorean islands. All such species must overcome the gap between the Azorean islands and/or between the islands and the continents. This is quite possible, especially for richly diaspore-spreading species. However, I hypothesize that the principal hinder to the establishment of new bryophyte species, in the remote islands of the Azores, is the potent competition of already established bryo-communities on all sorts of substrates. Also, the influx of diaspores may not be large enough to secure an establishment there. The recent (last 50 yrs) influx of new species to the Azores has mainly been to sites within the low-altitude, profoundly maninfluenced landscape. There, competition from already established bryophyte species is much less potent than in the native plant communities in forest/shrub vegetation at altitudes above 500 m (cf. SJÖGREN 2003). Far-reaching changes of the composition of endemic Azorean bryo-communities within the remains of native Juniperus-Laurus-Erica forests are consequently not likely to take place within the near future. However, continued man-made changes within the Azorean high-altitude landscape, such as plantation of alien tree species, construction or improvement of roads and tracks, extension of areas of managed grasslands, plantation of invasive alien vascular plants may facilitate the influx of new bryophyte species, even there.