Diversidade de macroalgas marinhas bentônicas dos recifes de Maracajaú, área de preservação ambiental dos recifes de corais, Rio Grande do Norte, Brasil

Despite the importance of coral reefs to humanity, these environments have been threatened throughout the world. Several factors contribute to the degradation of these ecosystems. The Maracajaú Reef Complex, in Rio Grande do Norte state is part of the Coral Reefs Environment Preservation Area in northeastern Brazil. This area has been receiving an increasing influx of tourism and the integrity of the local reefs is a matter of concern. In this study, the reef macroalgae communities were studied and compared within two areas distinguished by the presence or absence of tourism activities. Two sample sites were chosen: the first one, where diving activities are intense; and the other, where these practices do not occur. Samples were collected at both sites within a quadrate of 625 cm2 of area randomly thrown 5 times along a 10 meters transect line. Richness, Shannon-Hill diversity and Simpson dominance indices were determined based on biomass data. Similarity between sites was analyzed with Bray-Curtis similarity and distance index. Fifty-eight macroalgae species were observed, including 7 Chlorophyta, 13 Phaeophyta and 38 Rhodophyta. In the non-disturbed site, 49 species were found, while at the disturbed site, there were 42 species. Dictyotaceae and Corallinaceae were the most representative families at the non-disturbed site, and Rhodomelaceae and Dictyotaceae at the disturbed site. The non-disturbed site presented a higher biomass and the greatest richness and diversity indices. In the disturbed site the dominance index was greater and Caulerpa racemosa was the dominant species. The dendogram based on similarity index showed two major clusters, and an isolated element at the center that corresponds to a sample from the disturbed site. In the first cluster, samples from the non-impacted site were predominant and fleshy brown algae were more conspicuous. The second cluster was composed primarily of samples from the impacted site, where C. racemosa and red filamentous and erect calcareous algae associations (turf forming) were observed covering large extensions. These associations are represented by groups of algae adapted to environments where disturbances are frequent. They can grow rapidly on substrate where benthic community was removed and do not allow the establishment of other species. The results of the present study show that tourism activity is an impacting factor that has been causing shifts in macroalgae communities in the Maracajaú Reef Complex

Caracterização da captura incidental de tartarugas marinhas pela pesca de espinhel pelágico no Nordeste do Brasil

The marine turtles biological characteristics and the impact they have been suffering in consequence of human activities have caused in the last decades the decrease of populations to unsustainable levels. All four of the species described in this paper are registered as endangered in a list by IUCN: Caretta caretta, Lepidochelys olivacea, Chelonia mydas, Dermochelys coriacea. The main causes of such impact include several fishing activities, mostly the surface longline. This paper discusses the monitoring of two foreigner longline fleet along the North East Brazilian coast between October of 2004 and September of 2005. Both operated in the West South Atlantic, one using the Chinese technique and the other the American. The American method s target species is the swordfish (Xiphias gladius), and it is characterized by using squid as bait, J 9/0 offset 5º hook, light sticks and night soaking. It also operates in shallower waters than the Chinese method. The source of information about the efforts and the catches came from onboard observers and were used to calculate the catching rate of turtles over 1000 hooks (CPUE). The American equipment caught more turtles (CPUE = 0,059; N= 103), mainly D. coriacea, while the Chinese longline caught mainly the L. olivacea and presented a CPUE= 0,018 (N= 89). The hooks were most frequently found attached to the mouth of C. caretta, C. mydas, and L. olivacea. The D. coriacea were most frequently caught by hooks externally attached to different parts of their body. There was no significant difference between the hook type catching and most turtles were still alive when released. The results suggest a greater potential of turtle catching by the American method. Besides the statistic tests have showed less interaction between the Chinese equipment and marine turtles, the catches of this fishing technique could have been underestimated due to miscommunication between the onboard observer and the vessel s crew plus the retrieve of the longline during night time