Larvas de Spongicolidae (Crustacea, Decapoda, Stenopodidea) do plâncton da região oceânica brasileira

Stenopodidea is comprised of the family Spongicolidae, which includes five genera (Spongicoloides, Spongiocaris, Spongicola, Paraspongicola, and Microprosthema), and the family Stenopodidae, with four genera (Engystenopus, Odontozona, Richardina, and Stenopus). In Brazil, Stenopodidea is represented by two species of the genus Stenopus and one of Microprosthema. For the present report, five larvae of two Spongicolidae collected during the cruise of the RV Thalassa between Rio Real (BA) and Cabo de São Tomé (RJ) were identified and described. Two species of Microprosthema were identified, one ascribed to M. semilaeve, the only member of Spongicolidae recorded until now in Brazil; and the other to an undescribed species of Microprosthema. The two species can be distinguished by the rostrum, which is as long as the carapace in M. semilaeve and shorter in Microprosthema sp.2; and by the presence of pleural spines on abdominal somites 1 to 3 in M. semilaeve and only on somites 2 and 3 in the second morphotype.Larvas de Spongicolidae (Crustacea, Decapoda, Stenopodidea) do plâncton da região oceânica brasileira. A infraordem Stenopodidea compreende as famílias Spongicolidae, que inclui cinco gêneros (Spongicoloides, Spongiocaris, Spongicola, Paraspongicola e Microprosthema), e Stenopodidae, com quatro gêneros (Engystenopus, Odontozona, Richardina e Stenopus). No Brasil, a infraordem Stenopodidea é representada por duas espécies do gênero Stenopus e uma de Microprosthema. No presente estudo, cinco exemplares de duas espécies de Spongicolidae coletadas durante o cruzeiro do RV Thalassa entre Rio Real (BA) e Cabo de São Tomé (RJ) foram identificados e descritos. Duas espécies de Microprosthema foram identificadas, uma atribuída a M. semilaeve, a única espécie de Spongicolidae registrada atualmente no Brasil, e outra atribuída a uma espécie ainda não descrita de Microprosthema. As larvas das duas espécies podem ser distinguidas pelo rostro, que é tão longo quanto a carapaça em M. semilaeve e mais curto na segunda espécie, e pela presença dos espinhos pleurais nos somitos abdominais 1-3 em M. semilaeve e somente nos somitos 2 e 3 no segundo morfotipo

Herbivorous copepods with emphasis on dynamic Paracalanus quasimodo in an upwelling region

A ressurgência transfere a água rica em nutrientes do fundo dos oceanos para a superfície, o que beneficia a produção primária e, consequentemente, aumenta a produção biológica local. Cabo Frio é favorecido pelo fenômeno e os copépodes são um dos grupos mais beneficiados. Os resultados mostraram que Pacalanus quasimodo foi a espécie mais abundante em relação às demais devido sua resposta rápida à floração. Assim, este estudo tem como objetivo avaliar a herbivoria e dinâmica das populações de copépodes, com ênfase em P. quasimodo. Os resultados mostraram que a temperatura influencia a produção primária, que, por sua vez, favorece a biomassa séston (R2 = 0,65, p = 0,008). A dominância de P. quasimodo deveu-se à disponibilidade de alimento (R2 = 0,83) e a elevada densidade da população leva a um decréscimo da diversidade (R2 = 0,63, p = 0,002). Nossos resultados revelaram que a predação por copépodes carnívoros, como Corycaeus spp. e Oncaea spp., é o principal fator que afeta a dominância de P. quasimodo (R2 = 0,70, p = 0,004; βcopépodes predador = 0,41, p = 0,04).Coastal upwelling is known to transfer the nutrient-rich water from the deep ocean to the surface, which benefits primary production and consequently increases local organic production. Cabo Frio is favored by the phenomenon and copepods are one of the groups most benefited. According to the results presented here, the higher abundances of Pacalanus quasimodo relative to other species are due to its rapid response to upwelling-dependent blooms. Therefore this study aims to assess the herbivory and dynamics of many copepod populations with emphasis on P. quasimodo. The results showed that temperature influences primary production, which in turn benefits the seston biomass (R2 = 0.65, p = 0.008). The dominance of P. quasimodo was due to its emphasis on herbivory (R2 = 0.83) and lead to a decrease in the planktonic diversity (R2 = 0.63, p = 0.002). Our results revealed that predation by carnivorous copepods, like Corycaeus spp. and Oncaea spp. is the main opposing factor affecting P. quasimodo dominance. (R2 = 0.70, p = 0.004; βpredators = 0.41, p = 0.04)

Multi-scale temporal variation of marine femtoplankton and picophytoplankton: the role of size and environment

Femtoplankton and picophytoplankton organisms exert a major role in the balance between producers and consumers and are responsible for a large part of net primary production in the ocean. However, despite their ecological importance, the magnitude and drivers of their temporal dynamics remain largely unexplored. To address this significant knowledge gap, we performed weekly sampling over ten months in a wind-driven coastal upwelling area in the subtropical South Atlantic Ocean. We combined this intensive feldwork with multi-color fow cytometry and statistical modeling to investigate the temporal changes of both femto- and picophytoplankton at multiple temporal scales. We found that femtoplanktonic organisms (including virus-like particles) responded faster (i.e., without a temporal lag) to environmental changes, mainly related to chlorophyll-a (chl-a) and phaeopigment variations. On the other hand, picophytoplanktonic organisms showed a slower response to environmental changes, with positive responses to variation in pH and NH4 concentrations after a one-week lag. Overall, our results demonstrate that the speed of response of planktonic organisms to environmental changes may be dependent on their size, which highlights the importance of environmental variables and biological interactions as drivers of their temporal dynamics

Dynamic of decapod crustacean larvae on the entrance of Guanabara bay

In the present study, we observed seasonal variations in the density of decapod larvae as well as changes in density related to diurnal and tidal cycles. Among the decapod larvae collected, portunids and grapsids were the most abundant, especially during nocturnal ebb tides and near the surface. The same results were obtained in late winter (September) and late summer (March). These results demonstrated a flow of decapod larvae from Guanabara Bay to adjacent coastal waters. Luciferid (Lucifer faxoni) was the only group with high densities during flood tides and we suggest this is an evidence of L. faxoni larvae entering Guanabara Bay in late winter. Probably these changes in distribution of Lucifer faxoni among winter and summer were related to reproductive cycle in the bay. For the portunids, grapsids and ocypodids, a similar dispersion strategy was observed towards adjacent coastal waters in the surface during nocturnal ebb tides

Larvae of Spongicolidae (Crustacea, Decapoda, Stenopodidea) from the plankton off Brazilian coast

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Inter-annual cascade effect on marine food web: A benthic pathway lagging nutrient supply to pelagic fish stock.

Currently, spatial and temporal changes in nutrients availability, marine planktonic, and fish communities are best described on a shorter than inter-annual (seasonal) scale, primarily because the simultaneous year-to-year variations in physical, chemical, and biological parameters are very complex. The limited availability of time series datasets furnishing simultaneous evaluations of temperature, nutrients, plankton, and fish have limited our ability to describe and to predict variability related to short-term process, as species-specific phenology and environmental seasonality. In the present study, we combine a computational time series analysis on a 15-year (1995-2009) weekly-sampled time series (high-resolution long-term time series, 780 weeks) with an Autoregressive Distributed Lag Model to track non-seasonal changes in 10 potentially related parameters: sea surface temperature, nutrient concentrations (NO2, NO3, NH4 and PO4), phytoplankton biomass (as in situ chlorophyll a biomass), meroplankton (barnacle and mussel larvae), and fish abundance (Mugil liza and Caranx latus). Our data demonstrate for the first time that highly intense and frequent upwelling years initiate a huge energy flux that is not fully transmitted through classical size-structured food web by bottom-up stimulus but through additional ontogenetic steps. A delayed inter-annual sequential effect from phytoplankton up to top predators as carnivorous fishes is expected if most of energy is trapped into benthic filter feeding organisms and their larval forms. These sequential events can explain major changes in ecosystem food web that were not predicted in previous short-term models

Neustonic patch of Moreiradromia antillensis (Stimpson, 1859) (Crustacea: Brachyura: Dromiidae) megalopae over the shelf-break: evidence of synchronism in pre-settlement larval pool

This study reports for the first time patches of Moreiradromia antillensis megalopa in superficial waters over the shelf-break and addresses their relevance as evidence of synchronism in the planktonic larval pool. Patches were registered during a plankton survey conducted between 13o and 22o S, over the shelf break in the central coast of Brazil.Este estudo relata pela primeira vez, manchas de megalopas de Moreiradromia antillensis em águas superficiais da plataforma e discute sua relevância como evidência de sincronismo na formação de pool larval. Manchas foram registradas em estudo do plâncton entre 13° e 22° S, sobre a quebra de plataforma na Costa Central do Brasil