Revista de Biología Tropical

A story of disturbance and loss: historical coral reef degradation in Bahía Culebra, North Pacific of Costa Rica

Sònia Fabregat-Malé, Juan José Alvarado — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Climate change and other multiple stressors have globally caused the collapse of many coral reefs. Understanding how coral reefs have responded to previous disturbances is key to identify possible trajectories in the face of future more frequent and intense disturbances.

Objective: We review the ecological history of coral reefs in Bahía Culebra, a historically important area for coral reef development in the North Pacific of Costa Rica, which has suffered extreme deterioration in the last decades.

Methods: We assessed historical traits of coral reefs using both historical and recent data, divided as follows: (i) the “pre-disturbed” period (1970–2000), (ii) the early degradation period (2000–2010), and the degraded period (2010–present day).

Results: Forty years ago, Bahía Culebra harbored the highest coral species richness in the Costa Rican Pacific, with high live coral cover (> 40 %). Signs of early degradation were observed after El Niño events and unprecedented coastal development that caused anthropic eutrophication, which led to coral death and a shift to macroalgae-dominated reefs. In the last decade, a steep decline in live coral cover (1–4 %), the loss of many reefs, and a decrease in reef fish diversity and abundance were recorded.

Conclusions: To promote the recovery of coral reefs in the bay, we propose management actions such as marine spatial planning, mitigation and monitoring of stressors, and ecological restoration. The latter could help turn the tide by increasing live coral cover, eventually leading to ecosystem functionality recovery, with spill-over effects on reef-associated communities, including local coastal communities. Nonetheless, such actions need governmental and local support; thus, raising awareness through environmental education and citizen science programs is key for the long-needed conservation of coral reefs in Bahía Culebra.

Diversity of freshwater crab: new distributional data for four species (Decapoda: Pseudothelphusidae) from Meso- and South American countries

Célio Magalhães, Ingo S. Wehrtmann — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: The Pseudothelphusidae is a very diverse family of primary freshwater crabs widely distributed throughout the Neotropical region, but the true extent of the geographic distribution of several species is poorly known because many of them occur in very remote areas with only a single or very few records available.

Objective: Here we present new country records for four species of pseudothelphusid crabs from Meso- and South American countries.

Methods: The data about the geographic distribution are based on specimens deposited in crustacean collections of institutions from Brazil, Germany, and USA; illustrations of the male first gonopod were prepared in stereomicroscope equipped with a camera lucida.

Results: Occurrence records of Phygiopilus acanthophallus Fredius stenolobus from Guyana, and Kunziana irengis from Brazil are published for the first time, and the occurrence of Raddaus mertensi from Honduras is confirmed. Comments on the morphology of the male first gonopod of each species are given, their range extensions are discussed, and the importance of these new records for conservation assessments is highlighted.

Conclusions: The new data expand the area of occurrence of these four species of Pseudothelphusidae freshwater crabs, providing new data that are relevant for taxonomic and biogeographical studies as well as for the development of better regional and national assessments of the conservation status of the aquatic fauna.

Freshwater crab research in Costa Rica: past, present and future

Ingo S. Wehrtmann, Célio Magalhães — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Freshwater crabs occur in tropical and subtropical regions around the world and are due to their large biomass an important component in ecosystem processes. In Central America, Panama and Costa Rica stand out for their high diversity with 17 and 15 of freshwater crab species, respectively.

Objective: Here we present an analysis of the freshwater crab research in Costa Rica and provide suggestions for future research topics related to these macro-invertebrates.

Methods: The analysis is based on publications dealing with freshwater crab research in Costa Rica. We included only publications that included specimens collected in Costa Rica; on the contrary, publications, which only mentioned freshwater crab species from Costa Rica were not included.

Results: The number of publications increased especially during the last two decades, reaching a total of 35 contributions. The history of freshwater crab research in Costa Rica might be divided into the following three periods: (1) Period I: pre-1900, the discovery phase as the start of freshwater crab research by the description of the first species from Costa Rica; (2) Period II: 1900–2000 when, after a long intermission, taxonomic studies on the freshwater crab fauna were resumed; and (3) Period III: post-2000 characterized by initiating studies including the ecology and molecular phylogeny of freshwater crabs while continuing the biodiversity assessment of these decapods.

Conclusions: Our knowledge about freshwater crabs in Costa Rica has increased considerably, especially during the last decades; however, information about many aspects of the life history and ecology of these invertebrates remains fragmentary or simply absent. Future research areas might include studies about ecology and behavior, the impact of climate change and other stressors (e.g., pollution, deforestation, habitat loss, and invasive species) on the existing populations as well as their role as intermediate hosts for metacercariae of the trematode Paragonimus spp. Finally, we stress the need to maintain and continue the collection of freshwater crabs in the Universidad de Costa Rica.

Interplay between light and temperature on growth of Chlorella sorokiniana (Chlorellaceae) cultures under laboratory conditions

Ana Margarita Silva Benavides, Giuseppe Torzillo — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: The relationship between light and temperature on the growth of Chlorella sorokiniana (Chlorophyceae) cultures was investigated under laboratory conditions.

Objective: The aim of this study was to evaluate the influence of different temperature and light intensities on growth, productivity, chlorophyll of Chlorella sorokiniana UTEX 1230 in laboratory conditions.

Methods: The cultures were exposed to a combination of two light irradiances (100 and 200 μmol photons m⁻² s⁻¹) and 5 different temperatures (20 °C, 25 °C, 30 °C, 40 °C, 45 °C).

Results: At 100 μmol photons m⁻² s^−1,the culture growth did not differ significantly within 20 °C and 35 °C range. At this irradiance, the maximum attained biomass dry weight was 3.9 g/l after 9 days of cultivation under continuous light. Cultures grown under 200 μmol photons m⁻² s^−1,showed much larger differences in their growth. Their final dry weight changed according to the following temperatures, 30 °C (6.19 g/l), 25 °C (5.24 g/l), 35 °C (4.33 g/l), 40 °C (2.50 g/l) 45 °C. Therefore, the optimal temperature for productivity of cultures of Chlorella sorokiniana, strongly changed according to the light intensities at which cultures were exposed. At 100 μmol photons m⁻² s^−1,a large plateau for optimal growth was observed between 20 °C and 35 °C, while at 200 μmol photons m⁻² s⁻¹ a clear optimal temperature for productivity was observed at 30 °C.

Conclusions: It was interesting to note that culture grown at 20 °C, performed well under 100 μmol photons m⁻² s⁻¹, while when exposed to 200 μmol photons m⁻² s⁻¹ they were unable to grow. No growth was achieved at 45 °C. Therefore, 40 °C represented the upper limit to appreciate the growth in Chlorella sorokiniana strain UTEX 1230, while the temperature lower limit changed with light irradiance.

Community-based identification of ecosystem services in Ramsar wetlands: a socio-ecological network approach

Vladimir González-Gamboa — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Ramsar wetlands are recognized worldwide for the ecosystem services they provide to society, for example they are source of food and water. However, the study of their socio-ecological complexity is often not focused on the local communities that directly interact with the ecosystem. However, the participation and involvement of local actors with wetland management authorities are key factors in achieving sustainability.

Objective: To study the socio-ecological relevance of Ramsar wetland ecosystem services at the community level in Costa Rica.

Methods: Information was collected from one participatory workshop, 27 interviews with community leaders, and a survey administered to 744 households. These methods were applied in 14 communities within seven Ramsar wetlands where interaction between the ecosystem and the communities is significant.

Results: Provisioning ecosystem services were most frequently mentioned by local leaders and households. The main product quantified was fish harvesting, except for the Térraba-Sierpe wetland where mollusks were the most collected wetland product. The social network of wetland actors shows that public actors are the principal actors interacting positively with wetland authorities. The socio-ecological network of wetland-collected products identified central products. The fish families that are relevant simultaneously for many wetlands are robalo (Centropomidae), roncador (Haemulidae), and pargos (Lutjanidae). Additionally, the Caribe Noreste, Térraba-Sierpe, and Gandoca Manzanillo wetlands are those where more diversity and quantity of products were identified.

Conclusions: The two socio-ecological networks highlight that two wetlands have conditions for high management tension, four have moderate tension, and only one has low tension for management.

Coverage, vegetation structure and carbon storage of the mangrove forest of Morales, Puntarenas, Costa Rica

Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Mangrove forests provide diverse ecosystem services. However, mangroves are one of the most impacted tropical ecosystems, mainly due to land use change, as has occurred in the Gulf of Nicoya in Costa Rica.

Objective: Analyze mangrove spatial cover over time, and forest structure, and the carbon storage of the mangrove forest of Morales, to generate a current base line of the state of the mangrove forest.

Methods: The study was carried out in the mangrove forest of Morales, Puntarenas, Costa Rica. Total mangrove forest area was calculated from aerial photographs between 1944 and 2020. In 2021, 5 × 5 m plots were sampled in the field. In each plot, trees were counted, they were identified to the lowest possible taxon, their height were measured, and their circumference to calculate their diameter, and soil samples of 4.5 cm depth and interstitial water were collected. The complexity index (CI) of the mangrove stand and the importance value (IV) were calculated for each mangrove genus. Organic carbon content (C_org) was calculated from allometric equations for trees and with loss on ignition for soil.

Results: The mangrove forest area decreased by 24 ha between 1944 and 2020, mainly because of the development of shrimp and salt ponds. The forest CI in 2021 was 18.3 and the genus of greatest importance was Rhizophora. The mangrove forest stores 48 Mg C_org/ha in living vegetation and 11 Mg C_org/ha in the soil up to 4.5 cm depth.

Conclusions: The mangrove forest structure and the carbon storage, in general, are similar to other mangrove stands in the Gulf of Nicoya. Considering only the carbon in the above ground living vegetation, the loss of 24 ha is equivalent to 4 224 Mg CO₂released. The feasibility of carrying out ecological restoration of the lost areas could be analyzed.

Contribution to the knowledge of Cladocera (Crustacea: Branchiopoda) from Costa Rica

Lidia Avilés-Vargas, Francisco Diogo Rocha Sousa, Gerardo Umaña-Villalobos — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: The topography of Costa Rica varies dramatically, from coastal lowlands to high mountain ranges and volcanoes up to 3 800 m.a.s.l.. In this landscape, lakes and wetlands are observed, harboring diverse crustacean fauna that is not yet thoroughly known. Freshwater fauna in Costa Rica has not been reviewed since the 1980s, but some species not previously reported in the literature have recently been found during limnological studies in the country.

Objective: A study of Cladocera was performed to increase the knowledge of this group in Costa Rica.

Methods: Sampling was carried out in small ponds and along lake shores, especially among the aquatic vegetation, which has not been included in regular limnological surveys. Samples were screened to extract all members of Cladocera, and these were identified according to the most recent taxonomic literature. Limnological literature on Costa Rican lakes was also examined to complement the list of species.

Results: A total of 26 taxa of Cladocera were identified, of which 15 are new reports in Costa Rica, and the total number of Cladocera species for the country has increased to 54. New records for Costa Rica are: Acantholeberis curvirostris, Acroperus tupinamba, Biapertura ossiani, Alonella dadayi, Anthalona verrucosa, Camptocercus dadayi, Chydorus dentifer, Chydorus sphaericus, Ephemeroporus tridentatus, Flavalona iheringula, Parvalona parva, Simocephalus mirabilis, Daphnia ambigua, Leydigia striata and Diaphananosoma brevireme. These include four species reported for the first time in Central America, including A. curvirostirs found in high-altitude bogs. Chydoridae was the most diverse family. Most species were found only at one site, and in very low abundances.

Conclusions: It was not possible to identify a few of the specimens, which suggests that the real diversity of Cladocera in Costa Rica is higher, and there might be some species yet to be formally described.

Inuk yuwi ta = let's play with the crab - the semiotic relationship of early Mesoamerican, lower Central and South American cultures with crabs (Decapoda: Brachyura)

Guillermo V. Jiménez, Myrna Báez-Sirias, Ingo S. Wehrtmann — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: The millenary tradition of the Bribri and Cabécar culture called Ak kuk (= pull of the rock) and/or Inuk yuwi ta (= let's play with the crab) consists of pulling a stone from one place to another collectively. For the Bribris it is the most important tradition and festivity. The instrument with the tied stone that they use for this task is graphically related to one of the most present and studied symbols in the iconography in Mesoamerica: the crossed bands.

Objective: To analyze, from an American perspective, the role of the crab (Decapoda: Brachyura) in early American cultures, in their cultural concepts up to the present day.

Methods: The human-crab relationship in Mesoamerica, lower Central and South America was studied in symbolism, cosmovision, cultural representations and iconography, ethnohistoric documentation, oral literature, and interviews.

Results: The present study demonstrates a close link to the present day with crabs, since they combined the morphology of crabs and humans and other animals to create biomorphic cultural representations, utilizing pareidolia as a creative resource to sophisticate their iconographic language, incorporating the biology, morphology and structural geometry of the crab as a positional and conceptual grid.

Conclusions: This study demonstrates the importance that brachyuran crabs had and still have in the first cultures of The Americas, the relation with crossed bands, highlight the relevance of the knowledge regarding the current culture of the Bribris and Cabécares deposited in the tradition Inuk yuwi ta (= let’s play with the crab), and the relation of this tradition with the collective, with the stone and with the water. This contribution allows an approach to the way in which these decapods were reflected in the artistic, ludic manifestations as well as in the cosmovision of the studied cultures.

Coral reefs restoration initiatives in Costa Rica: ten years building hope

Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Costa Rica has been recognized worldwide for its high biodiversity and the conservation actions it has implemented. One of the most iconic ecosystems are coral reefs, which have experienced strong anthropogenic and natural pressures in recent years. To ensure these ecosystems’ preservation and services, a series of coral restoration initiatives have emerged in the last ten years along both Pacific and Caribbean coasts.

Objective: To document the different advances of the various coral restoration initiatives Costa Rica’s Pacific and Caribbean coasts.

Methods: This review focuses on the implementation of the different reef restoration efforts, indicating the restoration techniques used, the coral species used in the nurseries, as well as the general results of survival and growth.

Results: The first coral restoration project in Costa Rica occurred in the 1990s and was the only such effort until the 2010s. In 2013, a pilot project began in the Golfo Dulce area, which was later replicated in other areas of the country, such as Manuel Antonio, Sámara, and Bahía Culebra on the Pacific coast, and more recently in Punta Cahuita in the Caribbean. Various artificial structures have been used as nurseries in the water column such as trees and ropes, and benthic structures such like A-frames, tables, and spiders, the former being very effective for branching species (Pocillopora spp.), while the rest have worked successfully both for branched and massive species (Pavona spp. and Porites spp.). The results shows a growth rates have been between 6 and 9 cm/year, with survival of 60–90 % of the branching and massive colonies. All sites were seriously affected by the El Niño 2023 phenomenon, with high bleaching values and loss of colonies in the nurseries and on the reef.

Conclusion: Despite geographic and oceanographic distinctions, these projects have emphasized local engagement and perception of coral reefs, fostered intersectoral public-private collaborations for financial and human resources, and operated within established governmental regulatory frameworks. All projects face vulnerabilities such as El Niño events and Harmful Algal Blooms.

Patterns of microplastic incorporation in larval and pupal cases of Limnephilus hamifer (Trichoptera: Limnephilidae)

Andrés Arias-Paco, Monika Springer — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Microplastics (MPs) are an omnipresent problem in the environment. However, research on the effects of microplastics on invertebrate organisms in freshwater ecosystems is relatively limited.

Objective: Our aim is to study the patterns of incorporation of MPs by Trichoptera larvae in the Neotropics.

Methods: We collected 30 fourth and fifth instar larvae of Limnephilus hamifer from Cerro de la Muerte, Costa Rica (2 764 m.a.s.l.) and transferred them to the laboratory, where we acclimatized them for 72 hours. We induced the larvae to leave their natural cases and deposited five in each of the following treatments: 100 % MPs, 75 % MPs, 50 % MPs, 25 % MPs and 0 % MPs, where the rest of the percentage corresponded to organic matter from the same collection site. In a sixth treatment, we deposited five larvae with their original cases on a 50 % MPs substrate. The MPs consisted of a proportional mixture of PET of four colors: orange, blue, green and transparent.

Results: We found that larvae from all treatments constructed their cases incorporating MPs, even when organic matter was available. In general, the cases made with MPs had a higher weight than the natural cases and those of the control group. Additionally, we observed that orange-colored MPs were more incorporated into the cases in all treatments, so possibly Trichoptera larvae have preferences towards the orange color. We also observed the incorporation of MPs in larvae with their original cases, and notably, we recorded the incorporation of MPs in pupal cases, something not reported in the literature at the moment. Conclusions: The incorporation of MPs in all treatments has important consequences because they can accumulate toxins that affect the organisms. The fact that MPs cases are heavier than natural ones could mean a problem in the mobility of the larvae on the substrate, which leads to a greater energetic wear. Finally, incorporating MPs into fixed structures such as pupal cases may make them more conspicuous to visual predators such as fish.

Does mesofaunal abundance and composition influence mangrove leaf litter decomposition?

Margarita Loría-Naranjo, Jeffrey A. Sibaja-Cordero, Jorge Cortés — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Litter decomposition in mangrove forest is a process in which organic matter produced as leaves in the trees is later transferred to the sediment. Several invertebrates participate in the fragmentation of leaves, and they might have a great impact in the later stages of decomposition of mangrove leaves.

Objective: The study aims to characterize mesofauna inhabiting leaf litter of Rhizophora racemosa, in the South Pacific of Costa Rica during the dry and rainy season.

Methods: Five pre-weighted litter bag samples were set out during each season. Each sample consisted of specimens adhered to the leaves after 0, 15, 30, 60, 90 and 120 days, from two sites in Térraba-Sierpe National Wetland. The samples were washed in a sieve (0.5 mm) and the organisms were separated and identified. Taxa were assigned to trophic groups to evaluate their influence in the decomposition of the leaves. Additionally, leaf detritus samples retained in the sieve were dried in an oven at 70 °C to calculate the remaining vegetal matter for each site and season.

Results: The most abundant taxa were: Bivalvia (26 %), Nematoda (19.45 %), Gastropoda (14.78 %), Nemertea (14.61 %), and Ostracoda (8.20 %). Based on the trophic classification of the mesofauna found, it is expected that most of them are indirect consumers of R. racemosa litter. Correlation analysis shows that, depending on the site and the season, the mass loss of leaf litter was greater with a greater mesofauna abundance. A combined influence of water salinity, temperature and dissolved oxygen explains 25 % of the changes observed in the mesofauna found in leaf litter samples throughout the sampling period.

Conclusions: Leaf litter decomposition process evidences the presence of an abundant and diverse mesofauna community. The abundance of this mesofauna seems to have a positive influence on the decomposition of the leaves. It is a vital issue to comprehend the role of mesofauna as potential consumers of mangrove leaf litter, in order to conservate biodiversity in this ecosystem.

Soft-bottom benthic assemblage changes due to tropical seasonal upwelling (Bahía Salinas, Costa Rican Pacific)

Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Seasonal upwelling is a displacement offshore of surface seawater and replacement by cool deeper water with higher nutrient levels by the influence of the wind. On the north Pacific coast of Costa Rica the upwelling is present from December to April.

Objective: Within this seasonal upwelling area, Salinas Bay was sampled to determine whether the upwelling has an effect on the diversity, composition, and trophic guilds of the soft-bottom benthic community.

Methods: The bay was visited during the upwelling and non-upwelling seasons of 2007-2009. A number of 6 to 9 grab samples were taken in each sampling event.

Results: Richness and abundance were lower in the non–upwelling season and the highest values were observed at the end of the upwelling. The taxa composition of assemblages varied partially across the seasons, depending on the upwelling intensity.

Conclusions: The species composition was more diverse and abundant at the end of the upwelling season than at the start or in the non–upwelling season. Differences in infaunal assemblages during the seasonal upwelling could be explained by the change in characteristics of the sediment-water interface, nutrients, and sediment movements that promote the increase of planktonic productivity, and thus food availability.

Climate Change Scenarios in the Southern Caribbean region of Central America

Tue, 04 Mar 2025 00:00:00 -0600

Introduction: Warming is already significant in Central America and the Caribbean and may be magnified even further in the future. A decrease in the precipitation is projected, increasing also regional aridity.

Objective: To study observed and projected latitudinal gradients for precipitation and temperature in three Southern Caribbean locations of Central America: Bluefields (Nicaragua), Limón (Costa Rica) and Bocas del Toro (Panamá) and to characterize their future changes and determine if there are differences or similarities in a north-south direction.

Methods: Monthly precipitation (P) and temperature (T) data from General Circulation Models from 1979 to 2099, were downloaded from the WRF repository. Data from the selected models from the repository were subjected to a delta-type statistical downscaling to bring them to a resolution of 1 x 1 km. These models are part of the latest generation of the Coupled Model Intercomparison Project-Phase 6 used by the Intergovernmental Panel on Climate Change. The ground-truth data necessary for bias correction were obtained from the ERA5 reanalysis. Monthly P and T data were downloaded from 1979 to 2014 at different native spatial resolutions and climatologies at 1 x 1 km spatial resolution at global scales were obtained from WorldClim data.

Results: Scenarios show that some regions would go from very humid to humid, based on strong reductions in precipitation and warming at the end of the 21st century. This expected increase in the aridity is going to have impacts on ecology and ecosystem services, agriculture, human consumption due to a water availability reduction per capita and hydroelectric generation.

Conclusions: Generation of high spatial Climate Change scenarios is necessary because Central America is a region characterized by significant topographic complexity, land use variety and spatial occurrence of hydrometeorological disasters. This intrinsic variability suggests that local risk management and planning strategies must be designed with a highly specific approach to each locality or region. This implies that, even in areas geographically near to each other, the measures taken may not necessarily be transferable due to differences in climate projections, as it was found for the three nearby communities in the Southern Central American Caribbean coastal region.

Community Structure of coral ecosystems in sites of importance for the conservation of marine biodiversity in the North Pacific of Costa Rica.

Mon, 03 Mar 2025 00:00:00 -0600

Introduction: The North Pacific of Costa Rica is a very dynamic region in oceanographic terms and has been identified as an important site for coral environments, with abundant coral communities and some of the most developed coral reefs on the Costa Rican Pacific coast. Nevertheless, these ecosystems have suffered degradation in the last years, a product of events of natural and anthropogenic origin.

Objective: This study determines the ecological state of the coralline ecosystems located in the Sites of Interest for the Conservation Golfo de Papagayo and Punta Gorda - Punta Pargos.

Methods: The coastline and geological formations (islands and islets) located in these SICs were explored, and rapid ecological evaluations were carried out, which included the characterization of the benthic, macroinvertebrate, and fish communities of each site.

Results: In 46 surveyed sites, three were identified as living coral reefs, 14 as dead coral reefs, and 29 as coral communities upon basalts, highlighting a low coverage of live coral (4.3 %) and a predominance of algae mats (64 %). A total of 79 fish species and 40 macroinvertebrate species were recorded, with significant variations in the community composition of these organisms between the three types of coral ecosystems characterized. Matapalo and Jícaro stand out as bright spots of reef development in the region.

Conclusions: This evaluation sheds light on the continuous alteration of these ecosystems over the last decades, without signs of significant improvements in their state. This reality underlines the urgency of taking effective measures of conservation and management to preserve and restore these coral and rocky reefs, in order to guarantee the sustainability of these valuable marine resources in the region.

Preliminary study on the arsenic removal capacity of native Costa Rican microalgae Chlorella vulgaris and Scenedesmus dimorfus (Chlorophyceae)

Tue, 04 Mar 2025 00:00:00 -0600

Introduction: The accumulation of heavy metals, such as arsenic, in aquatic ecosystems may lead to significant ecological and health issues, disrupting environmental stability and potential risks to human, plant, and animal health. Phytoremediation, particularly using microalgae as bioremediation, offers a promising approach to address these pollution challenges.

Objective: This study aimed to evaluate the arsenic removal capacity of two green microalgae species, Chlorella vulgaris and Scenedesmus dimorphus.

Methods: Both species were collected from water sources in Vuelta de Kooper ASADA 5, Aguas Zarcas, San Carlos. Initial strains of C. vulgaris and S. dimorphus were grown in BG11 culture medium under controlled light and temperature conditions. The biomass from each culture was resuspended in water samples from the ASADA in Aguas Zarcas (with known Arsenic concentration), and some reagents from the BG11 medium. Experimental treatments were conducted for 8 and 13 days for C. vulgaris, and for 12–13 days for S. dimorphus, with a control treatment. The total chlorophyll concentration, temperature, and pH were monitored.

Results: The results demonstrated a significant capacity for arsenic removal. C. vulgaris obtained an average arsenic removal of 20.51 % after 8 days of treatment and 31.67 % after 13 days. After 13 days of treatment, S. dimorphus showed an average arsenic removal of 47.19 %. According to bioaccumulation, both species exhibited bioaccumulation percentages greater than 97 %.

Conclusion: In conclusion, the arsenic removal and bioaccumulation data have demonstrated the potential of C. vulgaris and S. dimorphus as promising candidates for the phytoremediation of arsenic-contaminated waters.

Towards transdisciplinary and transformative coastal marine research: insights from Costa Rica

Astrid Sánchez-Jiménez, Maraja Riechers, Álvaro Morales-Ramírez — Tue, 04 Mar 2025 00:00:00 -0600

Introduction: Transformative transdisciplinary research (TTDR) aims to address complex sustainability issues of our times by engaging researchers from different disciplines, practitioners, individuals, and policymakers.

Objective: This literature review is a first structured effort to understand how marine-coastal research published in English and Spanish can drive transformative change towards sustainability in Costa Rica (n = 30 articles) and is expected to foster critical reflection on the role of scientific systems in the design, production, and use of knowledge.

Results: The results show that in Costa Rica, knowledge production remains largely unidirectional, with stakeholder consultation prevailing over co-production. It highlights the need to foster collaborative research that includes historically underrepresented groups, such as women. Power and funding dynamics determine research priorities, with efforts concentrated in the North Pacific, while the Caribbean region remains underrepresented.

Conclusions: Furthermore, we highlight ways forward to transformative research: a focus on leverage points such as co-production of knowledge, creation of safe spaces for inclusive dialogue, and reform of funding models to support long-term interdisciplinary collaboration. As Costa Rica will co-host the upcoming Ocean Conference in France, this moment presents an opportunity to align national research efforts with global transformative trends, ensuring that marine research evolves towards more inclusive and action-oriented frameworks.

Effect of temperature and salinity on the seagrass Halophila baillonii (Hydrocharitaceae) under aquarium conditions

Carla Olvido van Barneveld Pérez, Jimena Samper-Villarreal — Mon, 03 Mar 2025 00:00:00 -0600

Introduction: Halophila baillonii, also known as “clover grass”, is a rare seagrass species found in tropical waters off the American continent. This is a small and ephemeral species classified as Vulnerable in the IUCN Red List.

Objective: To determine how variations in temperature and salinity affect this seagrass.

Methods: H. baillonii was collected in the southern Pacific coast of Costa Rica either by hand or with a corer (8 cm diameter). Two experiments with three treatments each were carried out in aquaria. Each treatment was applied to three aquaria, for a total of nine aquaria per experiment. The temperature treatments consisted of 23 °C (Low), 28 °C (Control), 33 °C (High), with a constant salinity of 25 over 51 days. Salinity treatments were 15 (Low), 25 (Control), 35 (High) with a constant minimum temperature of 28 °C over 31 days. Five plant performance parameters were measured: 1) foliar shoot survival; 2) increase in the number of foliar shoots; 3) horizontal rhizome elongation; 4) rhizome internodal length; and 5) leaf area.

Results: H. baillonii survival rates were higher when collected manually rather than using a corer. All plant performance parameters were higher at 28 °C temperature (control). In contrast, variables of plant performance were similar in all salinity treatments, except that the seagrass presented smaller leaves at higher salinities. Female flowers were found towards the end of the experiments, being the first report of flowering of this species under aquaria conditions.

Conclusion: H. baillonii has a wide salinity tolerance, thus enabling plant survival during dry or rainy seasons. In contrast, H. baillonii appears to be more sensitive to lower and higher temperatures than 28 ºC. This is the first study reporting the response of this threatened species to experimentally induced fluctuations of temperature and salinity.

Relationship between herbivory of the green turtle Chelonia mydas (Testudines: Cheloniidae) with seagrass meadow structural complexity at Cahuita National Park, Limón, Costa Rica

Tue, 04 Mar 2025 00:00:00 -0600

Introduction: Seagrasses are habitat for the green turtle (Chelonia mydas). At Cahuita National Park (CNP), seagrass have been monitored since 1999. Over time, the canopy complexity of the dominant seagrass species (Thalassia testudinum) has declined. However, seagrass spatial variability and the turtle's interactions with these meadows at Cahuita remain poorly studied.

Objective: We aimed to assess the distribution and composition of seagrass meadows in CNP and quantify the intensity of C. mydas herbivory.

Methods: Seagrass meadows characterization was done in 2019 and 2021. Sampling points were distributed systematically every 200 m. When seagrasses were present, points were sampled every 50 m for greater resolution. Water depth and seagrass cover by species were quantified at each point. In 2019, additional metrics included sediment carbon content, shoot density, photosynthetic biomass, and leaf area index. Sea turtle density was calculated using aerial video transects, and abundance estimated from density and reef lagoon area. Herbivory rates were estimated by seagrass tethering experiments and underwater videos in 2021.

Results: Seagrass meadows were found at depths between 0.4–5.3 m. Mean sediment organic carbon was 2 % and increased slightly at higher seagrass biomass. Carbonate was 40 % and did not vary spatially. Seagrasses at CNP were dominated by T. testudinum, with minimal presence of Syringodium filiforme, Halodule wrightii, and Halophila decipiens. Between 2019-2021, seagrass cover declined by 52 %, from 54.7–24.7 ha in the area sampled both years. Sea turtle length ranged from 20-80 cm. Estimated density was 0.6 ± 0.6 turtles/ha and abundance was 36-211 turtles within the reef lagoon. Underwater videos showed that C. mydas is the main herbivore of T. testudinum in the meadow, with herbivory rates from 12–182 cm²/s.

Conclusions: Chelonia mydas plays a significant role in shaping seagrass canopy complexity and distribution at CNP, highlighting the need for integrated ecological monitoring and conservation efforts, particularly under the challenges posed by climate change and anthropogenic pressures.

Marine cyanobacteria of Costa Rica: published records

Laura Brenes-Guillén, Cindy Fernández-García, Jorge Cortés — Tue, 04 Mar 2025 00:00:00 -0600

Introduction: Cyanobacteria, also known as blue-green algae, are photosynthetic bacteria that play a crucial role in the marine environment, including food and oxygen production, nitrogen fixation, yield antibiotics and other bioproducts which might be used by other members of the community. Cyanobacteria remain understudied, particularly in the marine environments of Central America. While research on cyanobacteria has been conducted in Costa Rica, most studies have focused on freshwater environments, leaving a significant gap in understanding their diversity in the region.

Objective: This study compiles the diversity of marine cyanobacteria in Costa Rica through a review of scientific publications and herbarium collections.

Methods: a review of the scientific literature and cyanobacterial specimens from the Pacific and Caribbean from 1936 to the present was conducted. In November 2023, the Dr Luis A. Fournier Origgi Herbarium at the University of Costa Rica was visited to examine the available specimens.

Results: We found 50 records of cyanobacteria in the references and herbarium collections, of which 10 belonged to Sections I and II, 26 to Section III, nine to Section IV and five to the unclassified category. Genomic data from two studies were found in public databases.

Conclusions: The diversity of marine cyanobacteria in Costa Rica represents a valuable resource for ecological and evolutionary studies. This work provides a baseline for future research and highlights the importance of continuing to explore and document the biodiversity of these bacteria.

COVER

Sergio Aguilar Mora — Mon, 03 Mar 2025 00:00:00 -0600

First pages

Juan José Alvarado Barrientos — Mon, 03 Mar 2025 00:00:00 -0600