Control of Avicennia germinans recruitment and survival by Junonia evarete larvae in a disturbed mangrove forest in Colombia

1999 ◽  
Vol 15 (6) ◽  
pp. 791-805 ◽  
Author(s):  
Carola Elster ◽  
Laura Perdomo ◽  
Jaime Polanía ◽  
Marie-Luise Schnetter

In the Ciénaga Grande de Santa Marta, a brackish lagoon system on the Caribbean coast of Colombia, about 60% of the mangrove forests died from hypersalinization. The die-back was first encountered in 1964 and mass mortality started in the late 1960s. Although efforts are being made to reestablish the destroyed areas, regeneration is slow, which may be partly due to Junonia evarete caterpillars defoliating Avicennia germinans seedlings. The interaction between insects and seedlings was studied. Both J. evarete butterflies and caterpillars were abundant during the main rainy season, the time of highest fruit production in A. germinans. During the dry season the herbivore disappeared. The caterpillars fed exclusively on A. germinans propagules, seedlings, and pneumatophores. They preferred young seedlings to older plants and did not feed on trees. At some sites, 100% of the A. germinans seedlings died due to the caterpillar attack. Seedlings at open, disturbed sites were attacked more than seedlings protected by small roofs and trenches or those under a closed canopy. Only seedlings protected by insect nets or seedlings germinating at the beginning of the dry season had good chances of survival. The results suggest that in the highly disturbed areas of the Ciénaga Grande regeneration of A. germinans is strongly inhibited by the feeding behaviour of J. evarete caterpillars.

Crustaceana ◽  
2021 ◽  
Vol 94 (9) ◽  
pp. 1043-1058
Author(s):  
Marco Fusi ◽  
Joseph Bayi ◽  
Vanessa Ngo-Massou ◽  
Ndongo Din ◽  
Angela Sacchi ◽  
...  

Abstract The mangrove forests surrounding Douala, Cameroon, have a long history of human impact due to rapid urbanization, resulting in patches of true mangrove forest interspersed with areas dominated by the mangrove-associated Pandanus species. A survey carried out to assess the possible shift in crab fauna composition and dominance between mangrove and Pandanus dominated areas revealed an undescribed phytotelmic habitat for Platychirarma buettikoferi. This species was found colonizing the natural reservoirs of fresh water represented by Pandanus spp. Our results show P. buettikoferi to be ecologically dependent upon Pandanus spp., and absent on the mangrove floor and trees, strongly indicating a phytotelmic adaptation. Our data suggest that this species is a facultative phytotelmic species well adapted to Pandanus spp. dominated areas. Further studies on the reproductive biology and feeding behaviour of P. buettikoferi may shed light on this unique phytotelmic lifestyle and its role in mangrove ecosystem functioning.


Author(s):  
Allan G. Valle ◽  
Adriana M. Osorno Arango ◽  
Diego L. Gil Agudelo

Mangroves are trees or shrubs which represent a relevant link in the transmition between marine and land environments. With high importance at the biological and socio-economic level, mangroves constitute one of the strategic marine ecosystems of Colombia. Along the Caribbean coast of Colombia, mangrove forests are established around marshes or coastal lagoons; most of them have scarce scintific information which described these ecosystems at a qualitative level, but also which shows their biological processes and characteristics in a quantitative form. Given the importance of these ecosystems, the present work contributes to the direct and recent knowledge of the structure, distribution, abundance and regeneration capacity of the mangrove forest in Ciénaga de Cholón (Isla Barú, Bolívar province). Using surveys and in-situ observations, general height averages were calculated at 3.42 m, DAP at 4.94 cm and density of 21 trees 100 m-2, where seedlings was the dominant diametric category, followed by stem-wood; saplings constitued a smaller percentage. Mangrove species found were Rhizophora mangle and Avicennia germinans, with average heights of 3.45 and 2.93 m, and DAP of 4.45 and 3.29 cm respectively. Rhizophora mangle was the dominant species, being found in all the stations, while A. germinans was found only in two of the stations sampled, coinciding with particular soils requirements for the settlement and develoopment of each species. Regarding regeneration, a total of 117 R. mangle juvenile plants were evaluated in four stations, calculating a growth rate of 0.69 cm month-1 and a density average of 1.28 plants m-2. It is expected that the information obtained will allow for the evaluation of changes of this mangrove forest over time, contributing to guarantee the conservation and sustainable management of a valuable ecosystem and the National Natural Park Corales del Rosario y San Bernardo, sehre Cholón is located.


Author(s):  
Alberto Rodríguez Ramírez ◽  
Jaime Nivia Ruíz ◽  
Jaime Garzón Ferreira

Within the framework of the CARICOMP(Caribbean Coastal Marine Productivity) monitoring program, a study of the Avicennia germinans mangrove formation of Chengue bay (Tayrona Natural Park, Colombia) was performed between June 1995 and July 1996, based on the evaluation of structural and functional characteristics at three monitoring plots (10 x 10 m). The structure of the studied formation is coincident with that of fringing forests of the Caribbean region in having small trees (dbh=11.3 cm, total height=6.3 m) and high densities (16.3 trunks/0.01 ha). During the monitored period there was a low mortality rate (0.7 trees/year) and there were significant increases of the circumferences at breast height (as well as of the variables derived from this measure). Average tree growth rates expressed in height, dbh and basal area were 26.7 cm/year, 0.17 cm/year and 2.9 cm2/year respectively. Litterfall was composed principally by leaves (66.1%) and represented a mean production rate of 43.1 g/m2/month (5.2 t/ha/year). There was a temporal pattern of litterfall production associated with the climatic seasons in the area: during rainy months the production of total litterfall, leaves and fruits was higher, while during the dry season there was a reduction of these components and an increase of flowers and wood/twigs. Therefore, flowering and fruit production periods are fitted to an annual reproductive cycle. In general, the information gathered during this study is a new contribution to the knowledge of mangrove ecology in Chengue, and showed that the monitored trees had the conditions to grow and develop during the evaluated period.


2021 ◽  
Author(s):  
J. Aaron Hogan ◽  
Edward Castañeda-Moya ◽  
Lukas Lamb-Wotton ◽  
Christopher Baraloto

AbstractPhotosynthesis is an essential process to mangrove forest carbon cycling, which plays a critical role in the global carbon cycle. We investigated how differences in mangrove island micro-elevation (i.e., habitat) affect tree physiology in a scrub mangrove forests of the southeastern Everglades. We measured leaf gas exchange rates of scrub Rhizophora mangle trees monthly during 2019, hypothesizing that CO2 assimilation (Anet) and stomatal conductance (gsw) would decline with increases in water level and salinity, with larger differences at mangrove islands edges than centers, where inundation and salt stress are greatest. Water levels varied between 0 and 60 cm, rising during the wet season (May-October) relative to the dry season (November-April). Porewater salinity ranged from 15 to 30 ppt, being higher at mangrove island edges compared to centers. Anet maximized at 15.1 µmol m-2 s-1, and gsw was typically <0.2 mol m-2 s-1, both of which were greater in the dry than the wet season and greater at mangrove island centers than edges. After accounting for season and habitat, water level had a positive effect on Anet in both seasons, but no effect on gsw. Similarly, porewater salinity had a slightly positive marginal effect on Anet but a negligible effect on gsw Our findings suggest that water levels drive variation in Anet more than salinity in Everglades scrub mangroves, while also constraining Anet more than gsw, and that the interaction between permanent flooding and habitat varies with season as physiological stress is alleviated at higher-elevation mangrove island center habitats in the dry season. Additionally, habitat heterogeneity leads to differences in nutrient and water acquisition and use between trees growing in island centers versus edges, creating distinct physiological controls on leaf physiology and photosynthesis which could ultimately affect carbon flux dynamics of scrub mangrove forests across the Everglades landscape.


Author(s):  
Roger R Tabalessy

Coastal areas can either meet the human needs or give great contribution to the development. However, rapid infrastrural development in Sorong, west Papua, has been followed by high demand for mangrove timber and caused mangrove forest degradation due to exploitation. This exploitation could also result from high economic value of the mangrove timber. This study was done to analyze the economic value of mangrove wood utilized by the people to support the development process in Sorong. This study used primary data obtained through interviews and the economic value calculation of mangrove forests. It found that Sorong had mangrove economic value of IDR 165,197,833, 491. Wilayah pesisir selain dapat memenuhi kebutuhan hidup manusia juga memberikan kontribusi yang besar bagi pembangunan. Cepatnya pembangunan infrastruktur di Kota Sorong diikuti pula dengan tingginya permintaan akan kayu mangrove dan menyebabkan terjadinya degradasi hutan mangrove akibat eksploitasi. Eksploitasi ini disebabkan juga akibat kayu mangrove memiliki nilai ekonomi. Penelitian yang dilakukan ini bertujuan untuk menganalisis nilai ekonomi kayu mangrove yang dimanfaatkan oleh masyarakat Kota Sorong dalam proses menunjang pembangunan. Penelitian ini menggunakkan data primer yang diperoleh melalui hasil wawancara dan perhitungan nilai ekonomi hutan mangrove. Hasil penelitian ini menunjukkan nilai ekonomi ekosistem hutan mangrove yang berada di Kota Sorong adalah Rp165.197.833.491.


Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 989
Author(s):  
Basáñez-Muñoz Agustín de Jesús ◽  
Jordán-Garza Adán Guillermo ◽  
Serrano Arturo

Mangrove forests have declined worldwide and understanding the key drivers of regeneration at different perturbation levels can help manage and preserve these critical ecosystems. For example, the Ramsar site # 1602, located at the Tampamachoco lagoon, Veracruz, México, consists of a dense forest of medium-sized trees composed of three mangrove species. Due to several human activities, including the construction of a power plant around the 1990s, an area of approximately 2.3 km2 has suffered differential levels of perturbation: complete mortality, partial tree loss (divided into two sections: main and isolated patch), and apparently undisturbed sites. The number and size of trees, from seedlings to adults, were measured using transects and quadrats. With a matrix of the abundance of trees by size categories and species, an ordination (nMDS) showed three distinct groups corresponding to the degree of perturbation. Projection matrices based on the size structure of Avicennia germinans showed transition probabilities that varied according to perturbation levels. Lambda showed growing populations except on the zone that showed partial tree loss; a relatively high abundance of seedlings is not enough to ensure stable mangrove dynamics or start regeneration; and the survival of young trees and adult trees showed high sensitivity.


Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 637
Author(s):  
Huong Thi Thuy Nguyen ◽  
Giles E. S. Hardy ◽  
Tuat Van Le ◽  
Huy Quoc Nguyen ◽  
Hoang Huy Nguyen ◽  
...  

Mangrove forests can ameliorate the impacts of typhoons and storms, but their extent is threatened by coastal development. The northern coast of Vietnam is especially vulnerable as typhoons frequently hit it during the monsoon season. However, temporal change information in mangrove cover distribution in this region is incomplete. Therefore, this study was undertaken to detect change in the spatial distribution of mangroves in Thanh Hoa and Nghe An provinces and identify reasons for the cover change. Landsat satellite images from 1973 to 2020 were analyzed using the NDVI method combined with visual interpretation to detect mangrove area change. Six LULC classes were categorized: mangrove forest, other forests, aquaculture, other land use, mudflat, and water. The mangrove cover in Nghe An province was estimated to be 66.5 ha in 1973 and increased to 323.0 ha in 2020. Mangrove cover in Thanh Hoa province was 366.1 ha in 1973, decreased to 61.7 ha in 1995, and rose to 791.1 ha in 2020. Aquaculture was the main reason for the loss of mangroves in both provinces. Overall, the percentage of mangrove loss from aquaculture was 42.5% for Nghe An province and 60.1% for Thanh Hoa province. Mangrove restoration efforts have contributed significantly to mangrove cover, with more than 1300 ha being planted by 2020. This study reveals that improving mangrove restoration success remains a challenge for these provinces, and further refinement of engineering techniques is needed to improve restoration outcomes.


2020 ◽  
Vol 13 (1) ◽  
pp. 52
Author(s):  
Win Sithu Maung ◽  
Jun Sasaki

In this study, we examined the natural recovery of mangroves in abandoned shrimp ponds located in the Wunbaik Mangrove Forest (WMF) in Myanmar using artificial neural network (ANN) classification and a change detection approach with Sentinel-2 satellite images. In 2020, we conducted various experiments related to mangrove classification by tuning input features and hyper-parameters. The selected ANN model was used with a transfer learning approach to predict the mangrove distribution in 2015. Changes were detected using classification results from 2015 and 2020. Naturally recovering mangroves were identified by extracting the change detection results of three abandoned shrimp ponds selected during field investigation. The proposed method yielded an overall accuracy of 95.98%, a kappa coefficient of 0.92, mangrove and non-mangrove precisions of 0.95 and 0.98, respectively, recalls of 0.96, and F1 scores of 0.96 for the 2020 classification. For the 2015 prediction, transfer learning improved model performance, resulting in an overall accuracy of 97.20%, a kappa coefficient of 0.94, mangrove and non-mangrove precisions of 0.98 and 0.96, respectively, recalls of 0.98 and 0.97, and F1 scores of 0.96. The change detection results showed that mangrove forests in the WMF slightly decreased between 2015 and 2020. Naturally recovering mangroves were detected at approximately 50% of each abandoned site within a short abandonment period. This study demonstrates that the ANN method using Sentinel-2 imagery and topographic and canopy height data can produce reliable results for mangrove classification. The natural recovery of mangroves presents a valuable opportunity for mangrove rehabilitation at human-disturbed sites in the WMF.


2020 ◽  
Vol 63 (6) ◽  
pp. 537-540
Author(s):  
Fee O.H. Smulders ◽  
Kelcie L. Chiquillo ◽  
Demian A. Willette ◽  
Paul H. Barber ◽  
Marjolijn J.A. Christianen

AbstractThe dioecious seagrass species Halophila stipulacea reproduces mainly through fast clonal growth, underlying its invasive behavior. Here, we provide morphological evidence to show that the first findings of fruits in the Caribbean were misidentified. Consequently, H. stipulacea reproduction is likely still only asexual in the Caribbean. Therefore, we introduce an identification key of H. stipulacea reproductive structures to encourage careful identification and quantification throughout its invasive range. Until large-scale seed production in invaded habitats is reported, the apparent low rate of sexual reproduction needs to be considered in current studies investigating the invasion capacity of this species.


2016 ◽  
Vol 97 (6) ◽  
pp. 1417-1422 ◽  
Author(s):  
Barbara Calcinai ◽  
Azzurra Bastari ◽  
Daisy M. Makapedua ◽  
Carlo Cerrano

Mangroves create unique ecological environments, furnishing a habitat opportunity for many species. The majority of published information on mangrove sponges comes from the Caribbean while few data are available from Indo-Pacific mangrove sponges. In general, species diversity of sponges in mangroves is lower than adjacent subtidal habitats in both the Caribbean and Indo-Pacific. The aim of this study is to report the first data about sponge species diversity of two mangrove forests from Bangka Island (North Sulawesi, Indonesia) and to describe a new sponge species associated with the mangroves. The survey found 19 species, belonging to 11 families and 15 genera; the samples were collected on mangrove trunks, on the roots or on the surrounding bottom. The majority of the species are typical of coral reef but two of them have been previously found only in lagoons or in mangrove habitats. These new data enlarge our knowledge about Indonesian sponges diversity and suggest the urgency to consider Indonesian mangroves as an important but underestimated element in coral reef ecological dynamics.


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