This study aimed to qualitatively and quantitatively analyse the molluscan assemblages associated with a Halodule wrightii seagrass bed in a rarely studied area within a conservation unit in north-eastern Brazil. Seasonal and spatial changes in several seagrass meadow characteristics, including sediment, were evaluated to explain temporal and spatial variations in the molluscs found there. The molluscan community differed in its structure among periods and meadows, as well as in the composition of its infaunal and epifaunal assemblages. The results of this study indicated that molluscs are affected by the particular characteristics of a seagrass meadow, especially by its location in the intertidal zone, more than by the area of the meadow. Molluscs were also affected by other characteristics of the seagrass meadow, such as above-ground biomass and shoot density. Changes in all molluscan assemblages were also mediated by differences among months and seasons in this region of the western equatorial Atlantic, but not by seasonal changes of the meadow. The studied meadow was found to be one of the densest in Brazil, which has considerable importance to its associated fauna.

We examined the feeding ecology (diet, trophic width and trophic position) of five demersal shark species (Mustelus mustelus Linnaeus, 1758, Galeus melastomus Rafinesque, 1810, Scyliorhinus canicula Linnaeus, 1758, Scyliorhinus stellaris Linnaeus, 1758, Squalus blainville, Risso, 1826) coexisting in the north-eastern Aegean Sea (around Gökçeda Island) by combining stomach content and stable isotope analyses. The results indicate clear differences in diet between the five sharks. Cephalopods were mainly found in diet of S. stellaris and M. mustelus and the stomachs of G. melastomus, S. canicula and S. blainville included fish. S. blainville showed the highest trophic position in respect of stable isotope analysis (TPsia = 4.89) around Gökçeada Island. It was followed by G. melastomus (TPsia = 4.57). Direct isotopic values (both stable nitrogen and carbon) and isotopic niche width based on the Standard Ellipse Area (SEA) clearly differed among the five shark species. In particular, S. blainville was isotopically segregated from the other shark species studied, showing a narrow isotopic trophic niche and higher trophic level. In contrast, M. mustelus had the widest trophic niche of the five species studied. The niche width of S. stellaris was narrower than M. mustelus and S. canicula but wider than S. blainville and G. melastomus. SEA showed that G. melastomus has a specialized feeding strategy in the area. There is no overlap between S. canicula and S. stellaris in trophic width.

Many studies have already assessed how wave action may affect morphology of intertidal species among sites that vary in wave exposure, but few attempted to look to this issue in smaller scales. Using the most common limpet of the Brazilian coast, Lottia subrugosa, and assuming position on rocky boulders as a proxy for wave action at small scale, we tested the hypothesis that waves may also influence limpet morphology at a smaller spatial scale by investigating how individual size, foot area and shell shape vary between sheltered and exposed boulder sides on three shores in the coast of Ubatuba, Brazil. Limpets consistently showed a proportionally larger foot on exposed boulder sides for all shores, indicating that stronger attachment is an important mechanism to deal with wave action dislodgement at a smaller scale. Shell shape also varied in the scale investigated here, with more conical (dissipative) shells occurring in exposed boulder sides in one exposed shore across time and in the other exposed shore in one year. Shell shape did not vary regarding boulder sides across time in the most sheltered shore. Although we did not assess large spatial scale effects of wave action in this study, variations of the effect of waves at small spatial scale observed for shell shape suggest that it may be modulated by the local wave exposure regime. Our work highlights the importance of wave action at small spatial scales, and may help to understand the ecological variability of limpets inhabiting rocky shores.

Thermal stress events threaten coral populations by disrupting symbiosis between the coral animal and microalgal symbionts in its tissues. These symbionts are key players in the response of the coral holobiont to elevated temperature. However, little is known about the microalgal symbiont type in select corals in the north-western Philippines and how they contribute to the differential responses of coral species. Based on sequencing of major ITS2 bands from DGGE, the dominant algal symbiont in Acropora digitifera, A. millepora, A. tenuis and Favites colemani was identified to be closely related to ITS2 type C3u, Montipora digitata contained ITS2 type C15, and Seriatopora caliendrum hosted ITS2 types similar to C3-Gulf and D1. Thin branching corals, such as A. tenuis and S. caliendrum, exhibited the greatest reduction in photochemical efficiency (Fv/Fm) and symbiont density at elevated temperature, followed by M. digitata and A. millepora, to a lesser extent. A. digitifera and F. colemani were least affected by the temperature treatment. Reduction in Fv/Fm and symbiont density was more apparent in A. tenuis and A. millepora than in M. digitata and F. colemani, although these species all host ITS2 type C3u symbionts. These results suggest that the impact of elevated temperature is influenced by factors apart from symbiont type. This highlights the importance of further studies on the diversity of corals and their microalgal symbionts in the region to gain insights into their potential resilience to recurring thermal stress events.