Diversity of Seagrass-Associated Decapod Crustaceans in a Tropical Reef Lagoon Prior to Large Environmental Changes: A Baseline Study

The community composition of decapods associated with subtidal tropical seagrass meadows was analyzed in a pristine reef lagoon on the Mexican Caribbean coast in the summer of 1995 and winter of 1998. The macrophyte community was dominated by Thalassia testudinum followed by Syringodium filiforme, with interspersed rhyzophytic macroalgae and large patches of drift algae. In each season, 10 one-min trawls were made with an epibenthic sled (mesh aperture 1 mm) during the day and 10 during the night on each of five sites. In all, 53,211 decapods belonging to 119 species were collected. The most diverse taxa were Brachyura and Caridea, but the most abundant were Caridea and Anomura. Dominance was high, with three species (Latreutes fucorum, Cuapetes americanus, and Thor manningi) accounting for almost 50% of individuals, and 10 species accounting for nearly 90% of individuals. There was great similarity in community composition and ecological indices between seasons, but significantly more individuals and species in night versus day samples. In the 20+ years elapsed since the samples were taken, the reef lagoon has undergone substantial environmental changes due to extensive coastal development and, more recently, the decay of massive beachings of floating Sargassum macroalgae. This study constitutes a valuable baseline for future studies investigating the potential impact of these stressors on tropical seagrass-associated communities.

Synchronized sexual reproduction of the seagrass Syringodium filiforme (Cymodoceaceae) in a tropical reef lagoon on the Caribbean coast of Costa Rica

There has been an increasing effort to understand the mechanisms of sexual reproduction in seagrasses, which is usually synchronized. Synchronization is caused by environmental cues, such as temperature and light availability, and most likely occurs to maximize pollination success. At higher latitudes where seagrass reproductive seasons are clearly marked, intraannual variability of environmental triggers is significant. Our aim was to identify the period and frequency of sexual reproduction for the manatee grass Syringodium filiforme in a tropical coral reef lagoon, where the above-mentioned environmental triggers are homogenous all year round. The reproductive state and frequency and shoot length of S. filiforme were measured non-destructively in a monospecific patch on the tropical Caribbean coast of Costa Rica. The meadow was surveyed at 1 to 4-month intervals between May 2010 and May 2012. Water turbidity, temperature, and salinity were measured in situ. During the surveyed period, sexual reproduction of S. filiforme was detected in February and May, while seagrass shoot length showed no variation. The moment of seagrass sexual reproduction was not fully explained by the environmental parameters studied. Regardless of the limited environmental variability compared to previous studies at higher latitudes, synchronization of seagrass sexual reproduction at this tropical location is interesting and requires further studies on mechanisms and its possible adaptive advantage.

The Microbial Communities of Leaves and Roots Associated with Turtle Grass (Thalassia testudinum) and Manatee Grass (Syringodium filliforme) are Distinct from Seawater and Sediment Communities, but Are Similar between Species and Sampling Sites

Seagrasses are vital members of coastal systems, which provide several important ecosystem services such as improvement of water quality, shoreline protection, and serving as shelter, food, and nursery to many species, including economically important fish. They also act as a major carbon sink and supply copious amounts of oxygen to the ocean. A decline in seagrasses has been observed worldwide, partly due to climate change, direct and indirect human activities, diseases, and increased sulfide concentrations in the coastal porewaters. Several studies have shown a symbiotic relationship between seagrasses and their microbiome. For instance, the sulfur, nitrogen, and carbon cycles are important biochemical pathways that seem to be linked between the plant and its microbiome. The microbiome presumably also plays a key role in the health of the plant, for example in oxidizing phyto-toxic sulfide into non-toxic sulfate, or by providing protection for seagrasses from pathogens. Two of the most abundant seagrasses in Florida include Thalassia testudinum (turtle grass) and Syringodium filliforme (manatee grass), yet there is little data on the composition of the microbiome of these two genera. In this study, the microbial composition of the phyllosphere and rhizosphere of Thalassia testudinum and Syringodium filiforme were compared to water and sediment controls using amplicon sequencing of the V4 region of the 16S rRNA gene. The microbial composition of the leaves, roots, seawater, and sediment differ from one another, but are similar between the two species of seagrasses.

Seagrasses of Costa Rica: from the mighty Caribbean to the dynamic meadows of the Eastern Tropical Pacific

Seagrass meadows are declining worldwide, mostly attributed to anthropogenic disturbances. Understanding the dynamics of these meadows is urgent in order to establish adequate management and conservation strategies. Here, we analyzed the current knowledge on the seagrass meadows in the Caribbean and Pacific coasts of Costa Rica, Central America. Current knowledge was based on literature searches, herbarium collections, informal interviews, and personal observations. We report a total of five genera and seven species for Costa Rica: Thalassia testudinum, Syringodium filiforme, Halophila decipiens, Halophila baillonis, Halodule wrightii, Halodule beaudettei, and Ruppia maritima. Six species are reported for the Caribbean, and four species for the Pacific. Thalassia testudinum, S. filiforme, and H. decipiens have only been reported for the Caribbean. Halodule beaudettei has only been reported for the Pacific coast. Halophila baillonis, H. wrightii and R. maritima have been reported for both coasts. Seagrasses were found at a total of 31 locations in Costa Rica, most from the Pacific coast; 16 of which are reported here for the first time. Seagrass meadows from both coasts are vastly different. Along the Caribbean coast, meadows are often dominated by the robust T. testudinum, they are extensive and stable, persisting for decades. In contrast, the meadows along the Pacific coast are more dynamic and are dominated by pioneer and smaller ephemeral species, such as H. baillonis and H. beaudettei. The number of studies on Costa Rican seagrasses is scarce but has been increasing over time, and mostly concern taxonomic reports and basic descriptions of the dynamics of T. testudinum meadows from the Caribbean. Research, conservation and management efforts on Costa Rican seagrass meadows would benefit from continued monitoring and research on associated fauna and flora, incorporating ecosystem resilience and services.

18 Volumen XIX, Número 3 PHYTOCHEMICAL PROFILE AND EVALUATION OF PHOTOPROTECTIVE POTENTIAL OF Syringodium filiforme KÜTZING

Syringodium filiforme Kützing (Cymodoceaceae) is a marine seagrass abundant in Caribbean Sea, rich in phenolic compounds which have antioxidant properties and can provide new opportunities for treatment and prevention of diseases mediated by ultraviolet radiation like photoaging and skin cancer. The aim of this study was to evaluate the phytochemical profile and the photoprotective potential of S. filiforme leaf extracts . Total phenolic and flavonoid contents were 72.85 ± 0.72 mg pyrogallol equivalents/g dry extract (PE) and 59.09 ± 0.45 mg quercetin equivalents/g dry extract (QE), respectively. The total anthocyanins content was 1.35 ± 0.02 mg malvidin-3-O-glucoside equivalents/g dry extract (ME). The extract showed photoprotector potential in the UVB region. The S. filiforme treated mice showed a significantly decreased wrinkling score, and a reorganization of the collagen fiber was observed compared with irradiated and not treated skin. These results suggest that the crude extract of S. filiforme leaves may be a promising natural sunscreen product.