ICTIOFAUNA DE POÇAS DE MARÉ EM TERRAÇOS CONSOLIDADOS DO LITORAL AMAZÔNICO BRASILEIRO

As poças de maré são formadas pelo represamento de massas d’água durante a vazante e a sua troca ocorre ao longo de cada ciclo de marés, configurando em um ambiente explorado por várias espécies. A ictiofauna é um componente das poças de maré, algumas espécies são totalmente adaptadas (e.g. plasticidade fisológica, tamanho reduzido) e seu ciclo de vida ocorre apenas nas poças de maré. Contudo, muitas espécies utilizam as poças de maré em algumas fases do ciclo de vida para fins de alimentação, refúgio e reprodução. Considerando que os inventários são fundamentais para o conhecimento da biodiversidade, nosso estudo investigou a assembleia de peixes em poças de marés da Praia do Araçagy no período de outubro de 2016 a abril de 2017. No total, nós registramos 409 exemplares, pertencendo a 13 espécies, distribuídas em 11 famílias e sete ordens. Espécies residentes e estuarinas de importância comercial foram dominantes. INTERTIDAL FISHES OF THE CEMENTED TERRACES FROM BRAZILIAN AMAZON COAST: Tidal pools are formed by the damming of marine water during an ebb tide and their exchange occurs along each tidal cycle, configuring an environment explored by several species. The ichthyofauna is one of the components of the tide pools, with some species being fully adapted (e. g. physiological plasticity, reduced size) and their life cycles occuring uniquely on this environment. However, most species use tide pools at some stage of their life cycle for feeding, refuge and reproduction. Considering the main role of faunal inventories for the increase in biodiversity knowledge, this study investigates the fish assemblage in tide pools at Praia do Araçagy from October 2016 to April 2017. In total, were recorded 409 specimens belonging to 13 species, distributed in 11 families and seven orders. Resident and estuarine species with commercial importance were dominant.

First Report of the Marine Benthic Dinoflagellate Bysmatrum subsalsum from Korean Tidal Pools

Dense patches were observed in the tidal pools of the southern area of Korea. To clarify the causative organisms, the cells were collected and their morphological features were examined using light and scanning electron microscopy (SEM). In addition, after establishing strains for the cells the molecular phylogeny was inferred with concatenated small subunit (SSU) and large subunit (LSU) rRNA sequences. The cells were characterized by a nucleus in the hypotheca, strong reticulations in thecal plates, the separation of plates 2a and 3a, the tear-shaped apical pore complex, an elongated rectangular 1a plate and the absence of the right sulcal list. The thecal plate formula was Po, X, 4′, 3a, 7″, 6c, 4S, 5′′′, 2′′′′. Based on these morphological features, the cells were identified as Bysmatrum subsalsum. In the culture, the spherical cysts of B. subsalsum without thecal plates were observed. Molecular phylogeny revealed two ribotypes of B. subsalsum are identified; The Korean isolates were nested within the ribotype B consisting of the isolates from China, Malaysia and the French Atlantic, whereas the ribotype A includes only the isolates from the Mediterranean Sea. In the phylogeny, B. subsalsum and B. austrafrum were grouped. This can be supported by the morphological similarity between the two species, indicating that the two species may be conspecific, however B. subsalsum may distinguish from B. austrafrum, because of differences in the types of eyespots reported in previous studies. These findings support the idea that there is cryptic diversity within B. subsalsum.

Rocky tidal pools: carbonate chemistry, diurnal variability and calcifying organisms in future high-CO2 conditions

<p>Understanding the coastal ocean variability and quantifying its significance in the global biogeochemical cycles is crucial to our ability to project future changes. In the shallow coastal waters, the contribution of the biological activity to water chemistry can be high locally, and responsible for seasonal and diurnal variations. These variations are not yet well-understood: they are often under-estimated and the general lack of observations means that they are seldom integrated into global predictive models such as those used by the IPCC.<br>    In this presentation, we will present results on the natural carbonate chemistry diurnal variability in tidal rock pools in Brittany (France), during emersion times. We chose tidal rock pools as to represent "mini-coastal seas": realistic small mesocosms that simulate coastal environments with extreme variability. These have the advantage to be closed systems containing a range of calcifying organisms such as coralline encrusting and non-encrusting algae, that influence and are influenced by the carbonate chemistry. We calculated calcification of the pools community by using the alkalinity anomaly method and estimated the community photosynthesis/respiration. We also compared night-time dissolution and day-time calcification. Finally, we manipulated the pools chemistry at emersion by adding CO<sub>2</sub> to mimick future acidification changes, and explored the impact of seawater acidification on the calcification of the tidal pools' communities.</p>

Tides: A key environmental driver of osteichthyan evolution and the fish-tetrapod transition?

Tides are a major component of the interaction between the marine and terrestrial environments, and thus play an important part in shaping the environmental context for the evolution of shallow marine and coastal organisms. Here, we use a dedicated tidal model and palaeogeographic reconstructions from the Late Silurian to early Late Devonian (420 Ma, 400 Ma and 380 Ma, Ma = millions of years ago) to explore the potential significance of tides for the evolution of osteichthyans (bony fish) and tetrapods (land vertebrates). The earliest members of the osteichthyan crown-group date to the Late Silurian, approximately 425 Ma, while the earliest evidence for tetrapods is provided by trackways from the Middle Devonian, dated to approximately 393 Ma, and the oldest tetrapod body fossils are Late Devonian, approximately 373 Ma. Large tidal ranges could have fostered both the evolution of air-breathing organs in osteichthyans to facilitate breathing in oxygen-depleted tidal pools, and the development of weight-bearing tetrapod limbs to aid navigation within the intertidal zones. We find that tidal ranges over 4 m were present around areas of evolutionary significance for the origin of osteichthyans and the fish-tetrapod transition, highlighting the possible importance of tidal dynamics as a driver for these evolutionary processes.

Size and sex bias in air-exposure behavior during low tide of the intertidal hermit crab Clibanarius virescens (Krauss, 1843) (Decapoda: Anomura: Diogenidae)

Many species of the hermit crab Clibanarius (Diogenidae) live on rocky shores of tropical and warm temperate regions. Some of these species are known to climb out from tidal pools onto rock surfaces exposed to air during low tide. The ecological significance of this behavior, however, remains unclear. We investigated the differences between air-exposed and non-air-exposed Clibanarius virescens (Krauss, 1843) in relation to their body size, sex, and infestation by three species of parasitic bopyrid isopods. Our generalized additive model (GAM) analyses showed a significant effect of the “smoothing factor” of the interaction between body size and sex for the occurrences of the “air-exposure behavior.” The presence of the ectoparasitic isopods did not affect the air-exposure behavior. Females of C. virescens showed a more distinct trend than in males, whereas air-exposure in both sexes had a peak in approximately 3.0–4.0 mm shield size (comparatively larger size in females, and middle-size in males) and decreased after this size range. Intraspecific and/or interspecific competition for shells may be intense in hermit crabs of this size range because of size overlap, and the individuals that carry suitable shells may avoid such competition by actively escaping from tide pools at low tide.