Lopez-Calderon J.,Autonomous University of Baja California Sur |
Riosmena-Rodriguez R.,Autonomous University of Baja California Sur |
Rodriguez-Baron J.M.,National Polytechnic Institute of Mexico |
Carrion-Cortez J.,Autonomous University of Baja California Sur |
And 4 more authors.
Marine Biodiversity | Year: 2010
Human impact and global warming are driving major modifications to the world's ecosystems, the coastal zone being one of the most damaged. Seagrass meadows constitute coastal communities that have experienced great losses worldwide. The dominant seagrass in the meadows of the Pacific coast of North America is Zostera marina. There is evidence that Z. marina has been replaced in some places by the opportunistic seagrass Ruppia maritima with important implications for the trophic connections of local ecosystems. In México, there are few reports on the distribution and loss of seagrass meadows. Here, we report on the importance that R. maritima has gained in three wetlands of northwest México, replacing Z. marina and modifying local trophic networks. We made extensive samplings on Z. marina and R. maritima meadows, recording shoot density and marking their spatial distribution with GPS. We included information on the presence of R. maritima at other wetlands of northwest México from historical reviews and current sampling. R. maritima was recorded in 29 localities, 3 of which are new records. Their shoot density and spatial coverage were highest in late fall and decreased in late spring, while Z. marina meadows increased after the reduction of R. maritima meadows. R. maritima now constitutes a primary food source for green turtles in the sampled wetlands, something unprecedented a few years ago. Improvement of wetland management plans is needed to stop environmental degradation, R. maritima invasion, and the loss of ecosystem functions. © 2010 Senckenberg, Gesellschaft für Naturforschung and Springer.
Curran T.J.,The School for Field Studies |
Reid E.M.,The School for Field Studies |
Reid E.M.,Louisiana State University |
Skorik C.,The School for Field Studies |
Skorik C.,Wesleyan University
Restoration Ecology | Year: 2010
Restoration of ecological communities that can withstand future climate and land use changes requires information on species responses to various natural disturbances. Frost is an important disturbance that regulates plant species distributions, and although rare in tropical rainforest, it can occur in upland areas, especially where deforestation has occurred. We report the impacts of a severe frost that occurred in June and July 2007 on the Atherton Tablelands, Queensland, Australia and caused extensive damage to riparian restoration plots of upland rainforest species. We estimated proportion foliage retention to (1) compare impacts across 45 species; (2) examine the influence of plant height on frost effects; and (3) determine if plantings under shelterbelts of mature trees received less damage. Species exhibited different levels of foliage retention. Species that were particularly frost resistant included those from riparian habitats and a conifer. Some heavily impacted species are deciduous and may survive frost by shedding leaves; this warrants further investigation. Plant canopy height above ground level was only weakly correlated to foliage retention. Sheltered plants were much less damaged than unsheltered conspecifics, suggesting a useful way to mitigate frost impacts. These principles should help guide the development of resilient ecological communities in frost-prone areas. © 2010 Society for Ecological Restoration International.
Avila E.,National Autonomous University of Mexico |
Avila E.,Autonomous University of Baja California Sur |
Riosmena-Rodriguez R.,Autonomous University of Baja California Sur |
Hinojosa-Arango G.,The School for Field Studies
Helgoland Marine Research | Year: 2013
The interactions between sponges and red macroalgae have been widely documented in tropical and subtropical environments worldwide, and many of them have been documented as mutualistic associations. Sponges, however, have also been frequently described as part of the associated fauna of rhodolith habitats (aggregations of free-living non-geniculated coralline macroalgae). Nonetheless, the types of interaction they establish as well as the role of sponges in these habitats remain unknown. In this study, the associations between sponges and rhodoliths were investigated in an estuarine ecosystem of the Mexican Pacific based on qualitative and quantitative data. A total of 13 sponge species were identified in five newly discovered rhodolith beds dominated by the non-geniculate coralline macroalga Lithophyllum margaritae. The sponge assemblages were strongly restricted to rhodolith habitats. The best predictor of sponge abundance (from 5.1 to 51.7 ind m-2) and species richness (from 2.6 to 6.1 sponge species m-2) was the rhodolith density rather than other population descriptors assessed (e.g., average size, branch density and sphericity). The identified sponges included a variety of forms: massive (46 %), encrusting (23 %), excavating (15 %), cushion-shape (8 %) and digitate (8 %). Moreover, more than 50 % of sponge species recorded (mainly massive and encrusting forms) were frequently found overgrowing and binding rhodoliths. Halichondria cf. semitubulosa and Mycale cecilia were the most common binding agents; these species bind an average of 3.1 and 6.6 rhodoliths per sponge individual, respectively. These findings reveal the importance of rhodoliths as habitat forming species, since these seaweed beds notably increased the substrate complexity in soft bottom environments. In addition, the relatively high abundance of sponges and their capability to bind rhodoliths suggest that these associated organisms could have an important contribution to rhodolith bed stability. © 2012 Springer-Verlag and AWI.
Preece N.D.,James Cook University |
Preece N.D.,Charles Darwin University |
Preece N.D.,Biome5 Pty Ltd. |
Lawes M.J.,Charles Darwin University |
And 6 more authors.
Forest Ecology and Management | Year: 2015
Few measurements for carbon sequestration, ratio of above-ground to below-ground biomass and wood density exist for young trees. Current allometric models are mostly for mature trees, and few consider trees at the sapling stage. Over four years we monitored the growth rates, from seedling to the sapling stage, of 490 trees (five native species) in environmental plantings, in the Wet Tropics of north-eastern Australia. Our biomass estimates were greater by several orders of magnitude in the first year (6× 10-3Mgha-1 cf. 4× 10-6Mgha-1), and two orders of magnitude less at four years than those derived from the national carbon accounting model (5× 10-1Mgha-1 cf. 13Mgha-1). We destructively sampled 37 young trees to accurately estimate the variation in below-ground and above-ground biomass (AGB) with stem size, and to derive a best fit model for predicting sapling biomass: lnAGB=-5.092+0.786 ln(Diam.base)2Height. Biomass expansion factors for young tree species ranged from 1.71 to 2.44, higher than average for tropical forests. Root:shoot ratios are consistent with mean estimates for mature rainforest. Stem wood densities ranged from 0.444 to 0.683Mgm-3 for the five species measured, which was 6.5% lower than published estimates for three of the species, and 12% and 27% higher for two species. Relative growth rates were faster for species with lower wood density in the first four years, but these species also had the lowest survival over the same period. The findings are significant for a number of reasons. Ecologically, they indicate that young rainforest trees invest more in leaves and branches than in stem growth. From a survival perspective, in the context of rainforest restoration, it is best to invest in species with higher wood densities. From a carbon accounting point of view, refinements to the models used for national carbon accounting are required that include the contribution of the sapling stage. Sapling growth rates were significantly different from those assumed in the national model, requiring growth rates to be increased after four years (as opposed to after 2years in the national model) before reaching an asymptote at some time in the future. This adjustment is essential to enable carbon farmers to judge the time it takes to receive returns from investment. Policies that encourage carbon plantings should take into account that young plantings grow slower than predicted by current national carbon accounting models. © 2015 Elsevier B.V.
Rodriguez-Salinas P.,Autonomous University of Baja California Sur |
Riosmena-Rodriguez R.,Autonomous University of Baja California Sur |
Riosmena-Rodriguez R.,Valle Private University |
Hinojosa-Arango G.,The School for Field Studies |
Muniz-Salazar R.,Valle Private University
Ecological Engineering | Year: 2010
Zostera marina is the dominant seagrass species in coastal lagoons on the western coast of Baja California Peninsula, and due to its coastal location it is threatened by natural and anthropogenic factors, as is happening in Puerto San Carlos, B.C.S., where a fish cannery unloads its wastewater to the beach. Apparently an extensive intertidal meadow replacement was established by great amounts of green macroalgae. We evaluated the possibility to mitigate the impacts of this cannery with transplants of Z. marina meadow using adult plants. The transplant experiment was made in two different seasons for which two undisturbed donor meadows were chosen: El Cuervo and San Carlitos. The winter one obtained a 30% and in San Carlitos 90% after 13 months and the autumn transplant in San Carlos obtained a 0% of survival after 3 months. The results of these transplant activities were reflected in the shoot density at the end of the experiment (San Carlos was of 482 shoots/m2 and San Carlitos of 818 shoots/m2s and agree with the density of the natural meadows. This experiment shows that it is possible to develop a small-scale seagrass restoration as mitigation for Baja California coastal lagoons which are under severe threat for coastal development. © 2009 Elsevier B.V. All rights reserved.
Hager A.,The School for Field Studies |
Fernandez Otarola M.,University of Costa Rica |
Stuhlmacher M.F.,George Washington University |
Acuna Castillo R.,University of Costa Rica |
Contreras Arias A.,University of Costa Rica
Agriculture, Ecosystems and Environment | Year: 2015
Understanding the processes that influence tree species composition in agricultural landscapes is essential for conservation of tropical biodiversity outside of protected areas. We analyzed the effects of landscape composition (amount of surrounding forest cover) and farm management (conventional vs. organic) on the diversity and structure of woody plant species assemblages in Costa Rican coffee agroforestry systems. We utilized information from a GIS land-use database, surveys of 1-ha plots located in 14 coffee farms and 4 forest fragments, and farmer interviews on management practices. The coffee farms harbored over 100 tree species, including 19% of the native tree species found in the surrounding forests. The majority of tree species on the farms were native (82%) to the study area and originated from natural regeneration (73%). Among the tree species that regenerated naturally, 71% were dispersed by animals. On the other hand more than half of the individuals were non-natives (55%) and originated from planting, which resulted in low species similarity between farms and forests and a low density for most native species on the farms. Forest cover within a 1000. m radius around the farms varied between 4 and 38%. Increasing forest cover around the farms had a significant, positive effect on species richness; especially on tree species dispersed by animals, and on species similarity between farms and forests. This suggests that the connection to natural forests increases seed dispersal into adjacent farms. The number of regenerated species was higher on the organic farms, but tree species richness was not affected by management type. Although species assemblages on the coffee farms are strongly determined by natural regeneration, the number of individuals contributed by these processes is low. Tree species conservation in agricultural landscapes would greatly benefit from protecting remnant forests, from facilitating natural regeneration processes and promoting native trees on farms, with particular attention to rare species. © 2014 Elsevier B.V.
Claydon J.A.B.,The School for Field Studies |
Mccormick M.I.,James Cook University |
Jones G.P.,James Cook University
Journal of Fish Biology | Year: 2014
Spawning sites used by one or more species were located by intensively searching nearshore coral reefs of Kimbe Bay (New Britain, Papua New Guinea). Once identified, the spawning sites were surveyed repeatedly within fixed 5m radius circular areas, for >2000 h of observations ranging from before dawn to after dusk spanning 190 days between July 2001 and May 2004. A total of 38 spawning sites were identified on the seven study reefs distributed at an average of one site every 60m of reef edge. Pelagic spawning was observed in 41 fish species from six families. On three intensively studied reefs, all 17 spawning sites identified were used by at least three species, with a maximum of 30 different species observed spawning at a single site. Spawning was observed during every month of the study, on all days of the lunar month, at all states of the tide and at most hours of the day studied. Nevertheless, the majority of species were observed spawning on proportionately more days from December to April, on more days around the new moon and in association with higher tides. The strongest temporal association, however, was with species-specific diel spawning times spanning<3h for most species. While dawn spawning, afternoon spawning and dusk spawning species were differentiated, the time of spawning for the striated surgeonfish Ctenochaetus striatus also differed significantly among sites. The large number of species spawning at the same restricted locations during predictable times suggests that these sites are extremely important on this low-latitude coral reef. © 2014 The Fisheries Society of the British Isles.
Schneller A.J.,Skidmore College |
Irizarry A.,The School for Field Studies
Ocean and Coastal Management | Year: 2014
Public art in Mexico has historically served as a platform for protest and social commentary. The purpose of this action research was to document sea turtle murals throughout Baja California Sur (B.C.S.), Mexico and to better understand the potential relevance of public art as an impetus for fostering pro-environmental attitudes, and the extent to which murals are a useful tool in efforts to protect the marine environment and the recovery of endangered species. Through qualitative research, we conducted 333 surveys and interviews with both adult and student participants in nine B.C.S. communities. Through descriptive narratives of participant responses, and Type I tabulations, we found evidence of outcomes that sea turtle murals may have in relation to respondent environmental attitudes about support for marine protections and the recovery of endangered species of sea turtles. Unexpected results from semi-structured interviews with respondents pointed weakly to the potential for murals in helping to shape pro-environmental behaviors towards the treatment and recovery of endangered sea turtles. The results of this action research may provide useful insights for improving management practices during future efforts to protect and restore marine environments and endangered species. That is, public participation in strategically placed community accessible art, may prove to be a valuable and innovative component of a broader suite of outreach and education initiatives used for bolstering community responsibility and empowerment for conservation of the marine environment. © 2013 Elsevier Ltd.
Arevalo J.E.,The School for Field Studies |
Newhard K.,The School for Field Studies
Revista de Biologia Tropical | Year: 2011
The construction of roads near protected forest areas alters ecosystem function by creating habitat fragmentation and through several direct and indirect negative effects such as increased pollution, animal mortality through collisions, disturbance caused by excessive noise and wind turbulence. Noise in particular may have strong negative effects on animal groups such as frogs and birds, that rely on sound for communication as it can negatively interfere with vocalizations used for territorial defense or courtship. Thus, birds are expected to be less abundant close to the road where noise levels are high. In this study, we examined the effects of road traffic noise levels on forest bird species in a protected tropical forest in Costa Rica. Data collection was conducted in a forest segment of the Carara National Park adjacent to the Coastal Highway. We carried out 120 ten minute bird surveys and measured road noise levels 192 times from the 19th to the 23rd of April and from the 21st to the 28th of November, 2008. To maximize bird detection for the species richness estimates we operated six 12m standard mist nets simultaneously with the surveys. The overall mist-netting effort was 240net/h. In addition, we estimated traffic volumes by tallying the number of vehicles passing by the edge of the park using 24 one hour counts throughout the study. We found that the relative abundance of birds and bird species richness decreased significantly with the increasing traffic noise in the dry and wet season. Noise decreased significantly and in a logarithmic way with distance from the road in both seasons. However, noise levels at any given distance were significantly higher in the dry compared to the wet season. Our results suggest that noise might be an important factor influencing road bird avoidance as measured by species richness and relative abundance. Since the protected forest in question is located in a national park subjected to tourist visitation, these results have conservation as well as management implications. A decrease in bird species richness and bird abundance due to intrusive road noise could negatively affect the use of trails by visitors. Alternatives for noise attenuation in the affected forest area include the enforcement of speed limits and the planting of live barriers.
PubMed | The School for Field Studies
Type: Journal Article | Journal: Revista de biologia tropical | Year: 2011
The construction of roads near protected forest areas alters ecosystem function by creating habitat fragmentation and through several direct and indirect negative effects such as increased pollution, animal mortality through collisions, disturbance caused by excessive noise and wind turbulence. Noise in particular may have strong negative effects on animal groups such as frogs and birds, that rely on sound for communication as it can negatively interfere with vocalizations used for territorial defense or courtship. Thus, birds are expected to be less abundant close to the road where noise levels are high. In this study, we examined the effects of road traffic noise levels on forest bird species in a protected tropical forest in Costa Rica. Data collection was conducted in a forest segment of the Carara National Park adjacent to the Coastal Highway. We carried out 120 ten minute bird surveys and measured road noise levels 192 times from the 19th to the 23rd of April and from the 21st to the 28th of November, 2008. To maximize bird detection for the species richness estimates we operated six 12 m standard mist nets simultaneously with the surveys. The overall mist-netting effort was 240 net/h. In addition, we estimated traffic volumes by tallying the number of vehicles passing by the edge of the park using 24 one hour counts throughout the study. We found that the relative abundance of birds and bird species richness decreased significantly with the increasing traffic noise in the dry and wet season. Noise decreased significantly and in a logarithmic way with distance from the road in both seasons. However, noise levels at any given distance were significantly higher in the dry compared to the wet season. Our results suggest that noise might be an important factor influencing road bird avoidance as measured by species richness and relative abundance. Since the protected forest in question is located in a national park subjected to tourist visitation, these results have conservation as well as management implications. A decrease in bird species richness and bird abundance due to intrusive road noise could negatively affect the use of trails by visitors. Alternatives for noise attenuation in the affected forest area include the enforcement of speed limits and the planting of live barriers.