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Toxic Element Concentrations in the Razorbill Alca torda (Charadriiformes, Alcidae) in Portugal
No full textThe present study provides the first data on inorganic element levels (As, Cd, Co, Cr, Cu, Hg, Mn, Pb, Se, and Zn) in juvenile, immature, and adult razorbills (Alca torda) collected along the central coast of Portugal. Element concentrations were assessed by ICP-MS in kidney, liver, muscle, and feathers of 28 razorbills, including 4 juveniles, 17 subadults, and 7 adults. The effect of age and tissue on element accumulation was also assessed. The detected levels in razorbills may indicate a possible contamination risk by Hg and Cr. With respect to bird tissues, higher accumulation of Se and Cd was detected in kidney, Zn and Pb in feathers, and As and Mn in liver. Age was found to affect the accumulation of Cd, Cr, Cu, Hg, and Mn, juveniles presenting higher levels of Cu and Mn than older individuals. In razorbill kidney, Zn–Hg constituted the most significant relationship among metal concentrations. Liver presented the highest number of significant relationships (mostly involving Zn and Co). With regard to feathers, the most significant relationships involved Se, Zn, Cr and Cu concentrations. Positive linear relationships were detected among kidney, liver, and muscle, with emphasis on relationships involving Se and Hg, which may be indicative of similar accumulation/regulation mechanisms in those organs. Element concentrations are discussed in view of possible detoxification mechanisms in seabirds
Catches of target species and bycatches of an artisanal fishery: The case study of a trammel net fishery in the Portuguese coast
No full textIn this work we studied an artisanal fishery targeting mainly soles (Solea senegalensis and Solea solea) and cuttlefish (Sepia officinalis) with trammel nets. Catches of target species, bycatches and discards were studied from October 2004 until August 2005 in the west coast of Portugal. A total of 37 sampling surveys onboard commercial fishing vessels were conducted. The number and weight of individuals of all species caught were registered, as well as the amount discarded and retained by fishermen. A total of 112 species were identified: Scomber japonicus, Chelidonichthys obscura and Callioynimus lyra were the most discarded fishes, corresponding to 28% in weight and 36% in number of discards. Discards represented 22%, in weight, of the total catches, while the amount retained by fishermen for consumption or direct selling was 12%, also in weight. The overall estimate of the annual discards value due to this fishery was ca. 170 tonnes, comprising near 45 fishing vessels. Inconsistencies between the catches recorded onboard and the official landings were detected for the main target species. Some bycatches of species under recovery plans were also found
Nocturnal and diurnal nearshore foraging of\ud European Storm Petrels Hydrobates sp. along the\ud Lisbon coast, Portugal
No full textDuring three days in June 2006, tens of European Storm-petrels Hydrobates\ud
sp. were observed foraging along the Lisbon coast during full daylight. On one morning along a 12\ud
km stretch of coast between Guincho and Parede a minimum of 135 different birds were observed\ud
foraging up close to the rocky shores and inside the Estoril bay. In September 2007 birds were observed\ud
fl ying towards the coast of Guicho Bay and foraging close to the shore near Cabo Raso. In September\ud
almost all birds were seen in the evening after sunset. Up to a maximum of 97 different birds were\ud
observed in one evening. It is discussed that the patterns of occurrence of the Storm-petrels nearshore\ud
in both periods must be explained by a combination of high food availability and a lowered predation\ud
risk. The observations in September 2007 of birds actively foraging nearshore in the dark are in line\ud
with two diet studies, where it was concluded that Storm-petrels regularly use inshore and nearshore\ud
areas at night to forage, based on found prey species in regurgitates, with one of the studies made in the\ud
southwest of Portugal. The observations in June 2006 are a novelty as they show that relatively intense\ud
nearshore foraging can also occur during the day and does not have to be confi ned to the darkness of\ud
the night. The low risk of predation in June, compared to other periods of the year when large numbers\ud
of gulls and Greater Skuas Stercorarius skua are present, might play a role here as well, like in\ud
nocturnal foraging. Although the observations in both June and September coincide with the main\ud
migration period of northern breeding populations of European Storm-petrels, attention is drawn to\ud
the possibility that local breeding might occur along the Portuguese coast. Effort is needed to check for\ud
breeding birds on the isolated islands in front of the coast of Cabo da Roca, being the best potential\ud
breeding locations in the region
Toxic Element Concentration in the Atlantic Gannet Morus bassanus (Pelecaniformes, Sulidae) in Portugal
No full textBycatch of crustacean and fish bottom trawl fisheries\ud from southern Portugal (Algarve)
No full textAs part of two research projects for analysing bycatch and discards, we quantified catch composition, catch\ud
rates, bycatch and discards in two important commercial bottom trawl fisheries (crustacean and fish trawls) off the southern\ud
coast of Portugal (Algarve). Stratified sampling by onboard observers took place from February 1999 to March 2001 and\ud
data were collected from 165 tows during 52 fishing trips. Commercial target species included crustaceans: blue and red\ud
shrimp (Aristeus antennatus), deep-water rose shrimp (Parapenaeus longirostris), Norway lobster (Nephrops norvegicus);\ud
and fishes: seabreams (Diplodus spp. and Pagellus spp.), horse mackerels (Trachurus spp.) and European hake (Merluccius\ud
merluccius). The trawl fisheries are characterised by considerable amounts of bycatch: 59.5% and 80.4% of the overall total\ud
catch for crustacean and fish trawlers respectively. A total of 255 species were identified, which belonged to 15 classes of\ud
organisms (137 vertebrates, 112 invertebrates and 6 algae). Crustacean trawlers had higher bycatch biodiversity. Bony fish\ud
(45.6% and 37.8%) followed by crustaceans (14.6% and 11.5%) were the dominant bycatch components of both crustacean\ud
and fish trawlers respectively. The influence of a number of factors (e.g. depth, fishing gear, tow duration and season) on\ud
bycatch and discards is discusse
Níveis de elementos tóxicos em Alca torda L. no litoral centro de Portugal
No full textNo presente estudo foram determinados os níveis de 10 elementos potencialmente\ud
tóxicos (As, Cd, Co, Cr, Cu, Hg, Mn, Pb, Se e Zn) nos rins, fígado, músculo e penas de\ud
28 tordas mergulheiras (Alca torda), incluindo 4 juvenis, 17 imaturos e 7 adultos. As\ud
aves foram recolhidas no litoral centro de Portugal, entre Aveiro e Peniche, no período\ud
entre 2005 e 2007.\ud
Verificou-se que a concentração dos elementos nos tecidos estudados estavam dentro\ud
dos limites aceitáveis, excepto o Hg e Cr que demonstraram valores um pouco acima\ud
dos referenciados, indicando um possível risco de contaminação. O Zn foi o elemento\ud
que apresentou valores de concentração mais elevados, especialmente nas penas.\ud
Apenas Cd, Cr, Cu, Hg e Mn revclwam uma acumulaç~od ependente da idade, sendo\ud
que as concentrações de Cu no fígado e penas e de Mn no fígado foram mais elevadas\ud
ern indivíduos juvenis. Não foi detectada nenhuma diferença significativa para a\ud
concentracão de Cu entre os vários tecidos na classe I e mercúrio na classe 3. Analisouse\ud
a existência de relações na acumulação entre os elementos no mesmo órgão e\ud
verificou-se a existência de várias relações lineares positivas, sendo que o músculo foi\ud
o tecido que revelou maior numero de relações significativas. Não se verificou\ud
nenhuma relação significativa envolvendo o Pb nos tecidos estudados. O Zn foi o metal\ud
que esteve envolvido nas relações mais fortes em todos os órgãos. No músculo\ud
destacam-se as relações entre o Cd-Hg, Mn-Co e Mn-Cu. Nos rins as relações Zn-Hg e\ud
Co-Hg foram as mais significativas, enquanto que no fígado as relações mais fortes\ud
foram Zn-Cr, Zn-Co e Se-Cu. Analisou-se ainda a existência de relações na acumulação\ud
do mesmo elemento mas em diferentes tecidos. Os elementos que revelaram a\ud
existência de relações lineares positivas foram o As, Cd, Hg e Se, envolvendo\ud
unicamente órgãos internos. O Hg foi o elemento que revelou o maior número de\ud
relações positivas entre os diferentes tecidos. A existência destas relações sugere que os\ud
elementos têm mecanismos de regulação semelhantes nos diferentes tecidos. ~ ~\ud
As concentrações de Hg e Cr relativamente altas podem indicar riscos de conhminaçiio\ud
ao longo da área de migraçgo das tordas mergulheiras ou pode reflectir os níveis de\ud
contaminação nas suas zonas de reprodu~ão.N o futuro, serão necessários mais estudos\ud
para identificar aquelas áreas mais poluídas, onde as aves possam estar expostas a\ud
níveis mais elevados de elementos tóxicos
Relatório de Actividades do Ano 2008:\ud Investigação Científica de Cetáceos ao Largo de Sesimbra
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CATCH AND BY-CATCH OF ARTISANAL FISHERIES IN THE ARRÁBIDA MARINE PROTECTED AREA (PORTUGAL)
Get PDFCatch and by-catch of artisanal fisheries (traps, trammel nets and longlines) in the Arrábida Marine Protected Area were studied. A total of 80 species were recorded for trammel nets, 36 for traps and 28 for longlines. Cephalopods accounted for more than 90% of the biomass captured with traps and fish dominated in catches of trammel nets and longlines (64% and 96%). Discards, in number of individuals,were higher for trammel nets (57%), followed by longlines (42%) and traps (14%).A larger number of species was identified more than 200 meters from the coastline for traps. A larger number of species was recorded in spring/summer for trammel nets. Catches were higher less than 200 meters from the coastline for longlines.Degradation, as a motive for discards, was very low in longlines. Catches below maturation size per sample day were relatively low for trammel nets and longlines target species and medium for traps. Statistical analysis revealed significant differences between the average profit per fishing day estimated for the three gears. The results show a high fishing effort being applied in the study area,causing impact on the marine environment, warranting further studies directed to target species in order to make way for a sustainable management
Diet and feeding intensity of sardine Sardina pilchardus: correlation with satellite-derived chlorophyll data
No full textSpatio-temporal variability of the diet of sardine Sardina pilchardus off Portugal was examined through analysis of the stomach contents of fish collected every 14 d from the west and south of Portugal during 2003/2004. Dietary composition of the modal sardine length class was assessed by determining the frequency of occurrence and carbon content of identified prey, and these 2 parameters were combined to estimate a modified index of relative importance of prey (mIRI). The most important prey for sardines were zooplankton, comprising crustacean eggs, copepods, decapods, cirripedes and fish eggs, dinoflagellates and diatoms (particularly the toxin-producer\ud
genus Pseudo-nitzschia), which together accounted for >90% of the estimated dietary carbon. Dietary seasonality was similar for both areas, except that the contribution of phytoplankton was higher for fish from the west Portuguese coast, where upwelling events are stronger and recurrent during spring and summer months. The predominance of prey <750 μm in sardine diet suggests that filter feeding is the dominant feeding mode used in the wild. Feeding intensity was similar for both sexes and for fish of different length classes and was higher on the west coast than in the south, which is probably related to the higher productivity of the west coast. Although there was high inter-annual variability in feeding intensity, this parameter was highest for both areas during spring and winter months. Temporal variability in satellite-derived chlorophyll a matched the temporal variability in the dietary contribution by phytoplankton and of sardine feeding intensity, suggesting further investigation of the potential use of satellite-derived chlorophyll a data as a proxy for sardine feeding intensity