Composição e distribuição de plâncton gelatinoso (cnidaria e thaliacea) na plataforma continental norte brasileira (Amazônia-Brasil)

Abstract

This study aims to characterize the composition and distribution of gelatinous zooplankton present along a transect in the Continental North Brazilian Platform. The collections were carried out in the period from 2013 to 2015 on seven cruises of environmental characterization in 06 stations along the Platform, reaching the isobath of 100, at the mouth of the Pará River. The temperature varied between 29.23 ± 0.12 oC in the C1E3 and 26.0 ± 1.12 oC in C6E6, with significant differences between the months of collection (H = 29.78; p 0.00). Salinity varied during the collection months, between 37.65 ± 6.71 in C6E6 and 9.11 ± 7.44 in C4E1, with significant differences between collection months (F = 5.67; p 0.43). Chlorophyll-a ranged from 31.78 ± 10.88 μg / l-1 in C5E1 to 0.48 ± 2.08 μg / l-1 in C3E, with significant differences between collection months (H = 27.44; p 0.00). During the entire study period 41 rates were recorded and identified at a generic and specific level. The total density of gelatinous during the collection period, the highest average total density among gelatinous was of cnidarians with a value of 117.69 ind / m3 in C7E1, and the lowest value of 0.02 ind / m3 in C3E4. Taliaceous, on the other hand, obtained the highest value of 164.40 ind / m3 in C7E3 and the lowest value of 0.03 ind / m3 in C2E4 (Figure 13), the total density showed significant differences only between months (F = 3.77; p 0.005), showing no significance between and collection stations (F = 0.20; p 0.656) and seasonal periods (F = 0.63; p 0.677). Among which, the species Liriope tetraphylla and Eudoxoides mitra stood out were responsible for the highest peak densities of cnidarians with the respective values 102.64 ind / m3 (H = 4.43; p 0.618) and 13.26 ind / m3 (F = 1.40; p 0.241). In the taliáceos the responsible for the biggest peaks of density were Doliolum sp. with 109.29 ind / m3 (H = 3.30; p 0.770) and cylindrical Iasis with 148.15 ind / m3 (H = 7.80; p 0.252). In view of the results presented, it was observed that the pluviometric indexes and, consequently, salinity and chlorophyll-a, constitute the central factors that regulate the composition and population dynamics of gelatinous.