Punta Galeta Research Articles

Seawater quality assessment of the marine ecosystem of Punta Galeta in Panama

Seawater quality was described in the Caribbean coast of Panama based on water physicochemical parameters and biological monitoring studies. Samples of water and benthic macroinvertebrates were collected near Punta Galeta, Province of Colón, Panama. The sampling area was sheltered from the action of waves and located between the coral reef and mangroves. Class Polychaeta was themost abundant with 90 % overall presence in Punta Galeta. Taxonomic classes of Bivalvia, Malacostraca and Ophiuroidea only represented 10 % altogether. Overall, seawater quality was suitable for the collected species of macroinvertebrates, even though concentrations of nitrateand phosphate were above the recommended value. Recorded values of temperature, pH and dissolved oxygen indicated that the site is far from reaching hypoxic conditions. Water quality index indicates a good water quality at Punta Galeta. Further studies with more robust and intense sampling programs are required to properly define the seasonal variations of water quality and its link to benthic macroinvertebrates. Similar studies in the Caribbean of Panama are scarce even though they offer valuable information for water resource administrators.

Enhancing the sustainable management of mangrove forests: The case of Punta Galeta, Panama

Mangrove forests fulfill essential socio-ecological roles, such as providing timber and other forest products, protecting coasts against erosion and rising sea levels, supporting healthy fisheries, and fostering biodiversity. Sustainable mangrove management (SMM) aims to address mangrove degradation and reverse trends of mangrove loss while empowering local stakeholders to participate in governance processes. This paper contributes to SMM scholarship through a case study of Punta Galeta, a protected mangrove forest located in the Colón District in Panama, near the Atlantic entrance to the Panama Canal. Our primary objective was to understand the challenges and opportunities associated with SMM in Punta Galeta and to identify insights of relevance to Panama and Latin America. We identified several successful SMM strategies, such as local awareness-raising on the socio-ecological benefits of mangrove forests and corporate sponsorship of mangrove restoration. However, several facets of SMM remained challenging, such as implementing and enforcing management plans and fostering regular communication and collaboration between all stakeholders. Findings suggest that local-level SMM requires a greater focus on strategies to enhance communication, collaboration, and trusting relationships between diverse stakeholders, as well as a more cohesive vision for the sectoral uses of coastlines. Further experimentation with different forms of social organization in support of local sustainable mangrove forest conservation and management are needed.

Mid to late Holocene sea-level rise and precipitation variability recorded in the fringe mangroves of the Caribbean coast of Panama

Throughout the Holocene, two of the most important factors involved in the evolution of tropical coastlines have been fluctuations in sea level and regional climates. The geological record provides insightful realizations of the complex interaction between these two factors, improving our understanding of the evolution of littoral zones. Here we present the sedimentary record of a mangrove swamp located in Punta Galeta, Caribbean coast of Panama. Through the conjunction of geochemical and biological sedimentary indicators, we reconstruct environmental dynamics of the area for the last ~5200 years. Between ~5200 and ~1800 cal yr B.P., the progressive dominance of carbonates and a decrease of mangrove pollen indicate increasing marine influence in the area, probably facilitated by a progressively drier climate. Between 3100 and 1800 cal yr B.P., the embayment was flooded by marine water resulting in a landward migration of mangroves. From ~1800 cal yr B.P. to present, the pollen and organic matter records indicate that mangrove vegetation belt recovered, contributing a large proportion of organic matter to the sediment and advancing the shoreline seaward. The maturation of the mangrove forest has resulted in a progradation process that offsets between 4 and 5 m of sea level rise occurred through the last ~5000 years. This process was facilitated by the progressive decrease in rates of sea level rise and by increasing sedimentation rates resulting from a higher accumulation of organic matter from the more vigorous vegetation and more terrigenic input associated with higher regional precipitation. The record of Punta Galeta demonstrates that the evolution of fringe mangroves throughout the Holocene has been mostly driven by sea level rise, which effects are potentially offset by erosion during times of high precipitation. Thus, across the Caribbean coast, precipitation regimes have played a pivotal role at defining the structure and function of mangrove communities. • Sea level rise has dominated coastal dynamics in Punta Galeta through the Holocene. • Mangroves have played a central role at counteracting sea level rise. • Precipitation variability has modulated the effect of sea level rise on the regional coastline.

Distribution of Plastic Debris in the Pacific and Caribbean Beaches of Panama

Microplastics are a global ubiquitous problem, which is becoming a major issue of concern at scientific and political levels around the world. This study presents physical and chemical characterizations of microplastic debris and a comparison between the spatial distribution and anthropogenic activities in 4 Panamanian beaches located in both sides of the Isthmus. Two of them (Juan Diaz and San Carlos beaches) are located toward the Pacific Ocean, Panamá Province, whereas the others (Palenque and Punta Galeta beaches) are located at the Caribbean Sea, Colón Province. They were chosen to show different landscape management and environmental impacts: touristic and protected areas; coastal areas that receive pollutants and marine litter from urban rivers or are used for local fishing activities. Plastic debris samples were collected and visually analyzed following the protocol proposed by the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP). The physical characterization of the samples consisted in the determination of variables associated with the number of plastic particles, shape, color, and size. The characterization of the polymers was performed by the attenuated total reflectance-Fourier transform infrared spectroscopy technique. A high concentration of microplastics (353 items/m2) were found at the studied sites at the Caribbean coast, whereas a lesser concentration with a greater diversity of shapes and polymer categories were found at the Pacific Coast (187 items/m2). The results indicate that, in addition to anthropogenic activities, the proximity to Panama Canal installations, as well as seasonality, natural phenomena, winds, and ocean currents may be influencing the increase in microplastic contents and the types of polymers observed.

Identification and Monitoring of Microalgal Genera Potentially Capable of Forming Harmful Algal Blooms in Punta Galeta, Panama

Coastal areas are attractive for human settlements because they allow easy access to benefits like food, security, and fishing. These aquatic ecosystems are supported by photosynthetic organisms that constitute the base of the food web. The term “Harmful Algal Bloom” (HAB) refers to the excessive proliferation of some taxa of these microorganisms reaching harmful levels to humans and other organisms. Biotoxins produced by these HABs could be transferred to the food chain and are the best-documented impact that HABs have on humans. The location and abundance of the HAB species producing the toxin is a good indicator of a possible human health hazard. The aim of this study was to monitor potentially harmful benthic/epibenthic microalgae in Punta Galeta, Panama over a 15-month period. The 3 main microalgae found were 2 dinoflagellates from the genera Prorocentrum and Ostreopsis and 1 diatom from the genus Coscinodiscus. Sampling made with both natural and artificial substrates yielded similar overall abundance patterns; however, for the macroalgae samples, there appeared to be significant host preferences for Ostreopsis and Coscinodiscus. Physicochemical measures taken at the site were found to fall within previously reported growth parameters for the microalgae found in the study.

SUPPLY-SIDE ECOLOGY IN MANGROVES: DO PROPAGULE DISPERSAL AND SEEDLING ESTABLISHMENT EXPLAIN FOREST STRUCTURE?

Theory and empirical evidence suggest that spatial and temporal variation in propagule availability can have as great or greater an influence on community structure as post-recruitment biotic interactions, a phenomenon known as supply-side ecology. One of the first theories to invoke supply-side dynamics, D. Rabinowitz's Tidal Sorting Hypothesis (TSH), attributed the tidal zonation of mangrove tree species to the interacting effects of water depth and propagule size on dispersal and establishment. According to the TSH, smaller propagules are carried farther inland by flood tides than larger ones, stranding and establishing in greater numbers at upper tidal elevations. In contrast, larger propagules are better able to establish in deeper, more seaward areas because their size affords greater access to the soil surface and resistance to buffeting by moving water. Here we present results of the first comprehensive investigation of the TSH. In a series of experiments conducted at Punta Galeta on the Caribbean coast of Panama, we quantified patterns of propagule dispersal and establishment of the three dominant species: Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle. To measure dispersal patterns, we monitored movements (directions and distances) of marked propagules released at three elevations along each of three transects. On all transects, regardless of species or elevation, propagules moved seaward rather than being carried inland by tides, as predicted by the TSH. Rates of seedling establishment were monitored in experiments conducted at different tidal elevations. Contrary to the TSH, all three species established best in the lower intertidal, where they were in prolonged contact with the soil surface during low tides, and established more poorly in the upper intertidal basin, where standing water made rooting difficult. Seedling establishment was lowest in the wave-exposed, back reef habitat, but in accordance with the TSH, the large propagules of Rhizophora rooted and persisted better in this turbulent habitat than did the smaller propagules of the other species. We conclude that the TSH does not explain the vertical distributions of mangrove species on Punta Galeta. Rather, a different form of supply-side dynamics imposed by the strong seaward movement of dispersing propagules is important in structuring our study forests.

Integration of object-based and pixel-based classification for mapping mangroves with IKONOS imagery

IKONOS 1-m panchromatic and 4-m multispectral images were used to map mangroves in a study site located at Punta Galeta on the Caribbean coast of Panama. We hypothesized that spectral separability among mangrove species would be enhanced by taking the object as the basic spatial unit as opposed to the pixel. Three different classification methods were investigated: maximum likelihood classification (MLC) at the pixel level, nearest neighbour (NN) classification at the object level, and a hybrid classification that integrates the pixel and object-based methods (MLCNN). Specifically for object segmentation, which is the key step in object-based classification, we developed a new method to choose the optimal scale parameter with the aid of Bhattacharya Distance (BD), a well-known index of class separability in traditional pixel-based classification. A comparison of BD values at the pixel level and a series of larger scales not only supported our initial hypothesis, but also helped us to determine an optimal scale at which the segmented objects have the potential to achieve the best classification accuracy. Among the three classification methods, MLCNN achieved the best average accuracy of 91.4%. The merits and restrictions of pixel-based and object-based classification methods are discussed.

Comparison of IKONOS and QuickBird images for mapping mangrove species on the Caribbean coast of Panama

Mangrove stands of differing species composition are hard to distinguish in conventional, coarse resolution satellite images. The new generation of meter-level satellite imagery provides a unique opportunity to achieve this goal. In this study, an IKONOS Geo bundle image and a QuickBird Standard bundle image were acquired for a study area located at Punta Galeta on the Caribbean coast of Panama. The two images cover the same area and were acquired under equivalent conditions. Three comparison tests were designed and implemented, each with separate objectives. First, a comparison was conducted band by band by examining their spectral statistics and species by species by inspecting their textural roughness. The IKONOS image had a higher variance and entropy value in all the compared bands, whereas the QuickBird image displayed a finer textural roughness in the forest canopy. Second, maximum likelihood classification (MLC) was executed with two different band selections. When examining only multispectral bands, the IKONOS image had better spectral discrimination than QuickBird while the inclusion of panchromatic bands had no effect on the classification accuracy of either the IKONOS or QuickBird image. Third, first- and second-order texture features were extracted from the panchromatic images at different window sizes and with different grey level (GL) quantization levels and were compared through MLC classification. Results indicate that the consideration of image texture enhances classifications based on the IKONOS panchromatic band more than it does classifications based on comparable QuickBird imagery. An object-based classification was also utilized to compare underlying texture in both panchromatic and multispectral bands. On the whole, both IKONOS and QuickBird images produced promising results in classifying mangrove species.

The Effect of Seed Predators on Plant Distributions: Is There a General Pattern in Mangroves?

Selective crab predation has been hypothesized to maintain mangrove forest zonation by preventing the establishment of certain species' seedlings at particular tidal elevations. Support for this hypothesis consists of observations that the propagules of some mangrove species are consumed at a rate that is inversely related to the species' relative abundance in the adult canopy. In addition, one previous study found that rates of crab predation were lower in large light gaps than in small ones. We conducted a mensurative field experiment to assay rates of crab predation on dispersing propagules of the dominant mangrove species (Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle) in our study forests at Punta Galeta on the Caribbean coast of Panama. The experiment specifically examined whether rates of crab predation varied 1) with species of propagule, 2) with changes in stand composition along the tidal gradient, and 3) inside versus outside of light gaps. Lightning-created canopy gaps are the primary sites of tree regeneration in these and other tall-stature mangrove forests. Propagules of the three mangrove species were tethered inside and in the understory surrounding nine light gaps, with representatives in each of the major stand types that occur along the intertidal gradient. Fates of propagules were monitored over a four-wk period. Rates of propagule predation varied spatially, with highest rates of removal occurring in lower intertidal R. mangle/L. racemosa stands, where the large herbivorous crabs, Ucides cordatus and Goniopsis cruentata are common. In mid- and upper intertidal stands, dominated by A. germinans or L. racemosa, where detritivorous Uca spp. are abundant but larger herbivorous crabs are rare, few propagules were consumed. The propagules of A. germinans were preyed upon more heavily than those of the other two species; rates of predation on R. mangle and L. racemosa propagules did not differ. Light environment (i.e. inside versus outside a gap) had no significant effect on the rate of propagule predation. The enhanced survival of juvenile mangroves in light gaps that we have observed is probably due to other factors such as higher light and nutrient availability, and in some situations, lower insect herbivory. Only the propagules of A. germinans experienced a pattern of predation consistent with the dominance-predation model: they were consumed at higher rates in the low intertidal where adults of the species are rare, and at lower rates in high intertidal areas where the species dominates the canopy. This suggests that predation on mangrove propagules by herbivorous crabs could influence the species composition of low intertidal forests by differentially reducing the recruitment of A. germinan On the other hand, rates of crab predation on A. germinans propagules seem insufficient to prevent A. germinans from establishing in low intertidal areas. In opposition to the dominance-predation hypothesis, crab predation cannot account for the distribution patterns of R. mangle or L. racemosa whose propagules were preyed on most heavily in lower intertidal areas where these species are very abundant. Our results, together with those of two earlier studies, indicate that predation by crabs on dispersing propagules is not a general explanation for the zonation of tree species along tidal gradients in mangrove forests.

EFFECTS OF THE 1986 BAHÍA LAS MINAS OIL SPILL ON REEF FLAT COMMUNITIES

ABSTRACT On April 27, 1986, about 75,000 to 100,000 barrels of medium-weight crude oil spilled into the Caribbean Sea from a refinery in Bahía Las Minas, Panama. After weathering for 13 days in warm, sunny conditions, the oil reached the intertidal reef flat and biological reserve at Punta Galeta, which had been under study since the early 1970's. The pre-spill data base consisted of detailed, time-series monitoring of sessile biota on the reef flat in relation to changes in sea and weather conditions. To assess the effects of the oil, this monitoring was expanded to other sites and continued after the oil spill. Within the resolution of our measurements, most detectable mortality of the sessile biota occurred in specific zones of the reef flats where factors such as winds, waves, water levels, and topography caused the oil to accumulate. Where the oil floated over the reef flats without prolonged accumulation, little mortality was recorded. The sessile biota regenerated from fragments surviving in place or washing in from nearby habitats, and the regeneration times ranged from less than one year to more than five years. For the sessile biota, there appeared to be no recolonization via planktonic larvae or spores. The fastest regeneration times were for species that propagated from fragments that survived in place; the slowest were for species that suffered nearly 100 percent mortality and recolonized from fragments washing in from subtidal habitats. Because regeneration of sessile species on tropical reef flats depends on regrowth from local survivors, control and cleanup of oil spills in these environments should be designed to maximize the survival of resident populations.

Meteorology and hydrography of a shoaling reef flat on the Caribbean coast of Panama

We describe the seasonal patterns and frequency distributions of meteorological and hydrographic conditions on a windward, shoaling reef flat at Punta Galeta, Panama (9° 24′ N lat.), between 1974 and 1985. The factors monitored were wind speed, wind direction, air temperature, rainfall, solar radiation, water level, water temperature, and salinity. All conditions showed strong seasonal periodicity; however, the timing, duration, and amplitude of the seasonal fluctuations differed among years. The greatest variation occurred in 1981 and 1982, leading into an El Nino event. Emergence of the reef flat and extremes of water temperature were the most apparent physiological stresses; both were dependent on mean water levels. The seasonal pattern of emergence time was inversely related to mean water level. Extreme water temperatures only occurred during low water tevels, ranging between 22° to >37°C in depths <15 cm, but staying between 25°C and 30.9°C in depths <35 cm. Water temperatures averaged 1.5°C higher than air temperatures. Although rainfall was 200 to 400 cm year-1, salinity remained between 24 and 36 ppt, with more than 98% of the records ≧30 ppt. The relationship of water temperature to depth is consistent with the hypothesis that the physical environment becomes more stressful when a reef reaches sea level and forms a shoaling platform.

Hydrographic and Meterological Studies of a Caribbean Fringing Reef at Punta Galeta, Panamá: Hourly and Daily Variations for 1977-1985

Hydrographic and Meterological Studies of a Caribbean Fringing Reef at Punta Galeta, Panamá: Hourly and Daily Variations for 1977-1985

AN OIL SPILL AFFECTING CORAL REEFS AND MANGROVES ON THE CARIBBEAN COAST OF PANAMA

ABSTRACT In April 1986, more than 50,000 barrels of medium weight crude oil were spilled into the largest complex of coral reefs and mangroves on the central Caribbean coast of Panama. Considerable amounts of oil came ashore at Punta Galeta, where a long-term environmental sciences program of the Smithsonian Tropical Research Institute provided extensive baseline information for investigating the effects of the oil spill. Immediate mortality was most apparent for organisms living at the seaward edge of the reef flats and on drying substrata above mean water level. By June 1986, a number of reef species were reduced in abundance, and a bloom of microalgae grew over much of the reef flat that had been directly exposed to the oil at low tide. The abundances of some fast-growing algae appeared to have recovered by September 1986, but the slower-growing corals, zoanthids, and calcareous algae were at the lowest abundances recorded. Defoliation and mortality of mangroves, particularly Rhizophora mangle, was severe on windward coasts, and other areas where the oil penetrated into sediments around the mangrove roots. Oysters and other organisms living on mangrove roots also suffered severe mortality. The types of habitats and organisms affected were obviously dependent on the particular weather conditions during the oil spill. Studies are continuing to follow succession and other changes in seagrass meadows, coral reefs, mangrove forests, and associated habitats that were affected by the oil.

Water-level fluctuations, emersion regimes, and variations of echinoid populations on a Caribbean reef flat

This paper examines fluctuations in water level over a Caribbean reef flat at Punta Galeta, Panamá. In an analysis of approximately ten years of records, the mean diurnal range of the tides was 24·5 cm and varied <2 cm from year to year. Daily mean water levels varied erratically over a range of approximately 30 cm. Monthly mean water levels fluctuated seasonally over a range of about 10 cm and were consistently higher than those at the regional tidal reference station at Cristóbal. On days with more wave action, water levels at Galeta increased relative to those at Cristóbal, suggesting that waves were ‘pumping’ water onto the reef flat. The monthly mean water levels at the two sites were not correlated, indicating that tidal data from conventional stations in deeper water cannot be extrapolated to reef flats, except as estimates of minimum potential water levels. Most of the reef flat was within 6 cm vertical span just below mean lower low water. The highest elevations within this range were exposed above water level for an average of 918 hours per year, as compared with 144 hours per year at the lowest elevation. Most exposures lasted less than 10 hours, with a modal duration of 3–5 hours; however, exposures longer than 12 hours occurred at nearly all elevations in all years. Exposures of the reef flat were most frequent between February and June and between August and November, a pattern apparently caused by a combination of seasonal oscillations of regional sea levels, the annual pattern of the solstitial tides, and waves generated by seasonal trade winds. The fluctuations in water levels apparently affected the abundances of some species of sea urchins on the reef flat. Populations of Lytechinus variegatus and Diadema antillarum declined or disappeared from the reef flat during seasons of repeated subaerial exposures, but recolonized the habitat in periods of higher water levels. Although they are reported to suffer heavy mortality during emersion, Echinometra lucunter and E. viridis did not exhibit reductions in abundance that were synchronous with the seasonal exposures of the reef flat.

Mass mortality of Diadema antillarum on the Caribbean coast of Panama

The ecologically important sea urchin Diadema antillarum suffered mass mortalities in 1983, first noted in Panama and then reported from the rest of the Caribbean. We documented the effects of this mortality at two localities on the Atlantic coast of Panama, Punta Galeta and the San Blas Archipelago. At Punta Galeta, affected by the mortality in January 1983, the numbers of D. antillarum changed from an estimated 14,000 per ha in June 1982 to 0.5 per ha in May 1983; by February 1984 they had increased to 38 per ha. In the San Blas, where mass mortality started in April 1983, the number of D. antillarum in permanent quadrats on 8 reefs was reduced by an average of 94.2%. The average reduction in population density measured in transects on nine reefs was 98.9%. Data taken in permanent quadrats on four reefs in 1978, 1979 and 1980 indicate that population fluctuations of D. antillarum are normally much smaller, justifying the labeling of the 1983 event as “mass mortality”. Size structure of the San Blas populations was also affected; mean test diameter of D. antillarum on four reefs was reduced from 48.6 mm to 25.0 mm. Other echinoids (Echinometra viridis, E. lucunter, Lytechinus variegatus, L. williamsi, Eucidaris tribuloides, Tripneustes ventricosus, Clypeaster rosaceus and Echinoneus cyclostomus) suffered no ill effects at either Galeta or the San Blas; their population densities remained stable or increased. Density determinations of Diadema mexicanum at the island of Taboguilla on the Pacific side of Panama indicate that Diadema mass mortality did not extend to the eastern Pacific. Sea surface temperatures, tidal levels, rainfall and salinity showed no abnormal fluctuations during the time of D. antillarum mass mortality at Galeta, suggesting that mortality was not due to physical stress. The wide geographical spread and species-specificity of the mortality suggest a water-borne pathogen as the most likely causative agent. Recovery of D. antillarum populations is likely to be slow because there are few, if any, unaffected populations in the Caribbean to contribute larvae for the recolonization of depleted areas. The absence of D. antillarum will probably be reflected by changes in the algal, coral and echinoid communities, and by altered patterns of bioerosion.