Mangrove Production Research Articles

Inter‐annual hydroclimatic variability in coastal Tanzania

AbstractClimatic controls regulate the coupled natural and human systems in coastal Tanzania, where mangrove wetlands provide a wealth of ecosystem services to coastal communities. Previous research has explained the precipitation seasonality of eastern Africa in terms of the local monsoons. This research examines a wider range of hydroclimatic variables, including water vapour flux, evapotranspiration, runoff, and ocean salinity, and the sources of low‐frequency atmosphere–ocean variability that support mangrove productivity and associated ecosystem services. Results confirm previous work suggesting that the northeast monsoon (kaskazi) largely corresponds to the “short rains” of October–December and extends through February, while the southeast monsoon (kusi) corresponds to the “long rains” of March–May and the drier June–September. The Indian Ocean Dipole (IOD) and, to a lesser extent, El Niño–Southern Oscillation (ENSO) are important modulators not only of precipitation (as has been shown previously) but also of water vapour flux, evapotranspiration, runoff, and salinity variability. During kaskazi, positive (negative) hydroclimatic anomalies occur during positive (negative) IOD, with a stronger IOD influence occurring during its positive phase, when seasonal anomalies of precipitation, evapotranspiration, and runoff exceed +50, 25, and 100%, and nearby salinity decreases by 0.5 practical salinity units. During kusi, the contrast between the positive and negative IOD modes is subtler, and the pattern is dictated more by variability in “long rains” months than in the dry months. The coincidence of the positive IOD and El Niño amplify this hydroclimatic signal. Because previous work suggests the likelihood of increased tendency for positive IOD and increased moisture variability associated with El Niño events in the future, wetter conditions may accompany the kaskazi, with less change expected during the kusi. These results advance understanding of the key environmental drivers controlling mangrove productivity and wetland spatial distribution that provide ecosystem services essential to the well‐being of the human population.

Global patterns of tree stem growth and stand aboveground wood production in mangrove forests

Mangrove forests provide important ecological and economic services including carbon sequestration and storage. The conservation and restoration of mangroves are expected to play an important role in mitigating climate change, and understanding the factors influencing mangrove stem growth and wood production are important in predicting and improving mangrove carbon sequestration and responses to environmental change. In this study, we collected data of individual diameter at breast height (DBH) growth rate and stand level aboveground wood production in both non-plantation (commonly termed as natural) mangroves and mangrove plantations across the world. Climatic factors, proxies of edaphic factors, as well as biological factors (e.g. mangrove species) were included as explanatory variables in the analyses to determine factors influencing the global patterns of tree growth rate and stand wood production of mangroves. Using hierarchical Classification and Regression Tree (CART) analysis we found interactions among environmental and biological factors in controlling mangrove tree growth rate and stand wood production. We also found different global patterns of tree growth rate and stand wood production between non-plantation mangroves and plantations. Climatic conditions (precipitation of driest season, precipitation seasonality) were the most important factors influencing the global pattern of tree DBH growth rate in non-plantation mangroves, with edaphic and biological characteristics also playing a role under specific climatic conditions. The global pattern of stand wood production in non-plantation mangroves was primarily determined by stand mean DBH growth rate of individual trees. However, in mangrove plantations management measures, specifically species selection and planting density, were the most important factors influencing the global patterns of tree growth rate and stand wood production. Our study provides parameters for a global estimation of long-term carbon sequestration in both non-plantation mangroves and mangrove plantations. In addition, our results help us better predict the dynamics of tree growth and carbon sequestration of non-plantation mangroves under changing climate.

Mangrove cover and cover change analysis in the transboundary area of Kenya and Tanzania during 1986–2016

ABSTRACTMangrove forests are among the most threatened ecosystems on earth. Some of these forests traverse national boundaries complicating their management due to differences in governance structures between countries. To improve the management of transboundary species regular monitoring is essential. Remotely sensed data were used to estimate forest cover and analyze conditions of mangroves in the proposed transboundary conservation area (TBCA) between Kenya and Tanzania. Image analysis was performed using unsupervised and supervised classification methods. The transboundary mangroves cover an estimated 11,906 ha; 55% being in Kenya, 45% in Tanzania. Ceriops tagal, Avicennia marina, and Rhizophora mucronata species co-dominate the mangroves of the transboundary area. The hotspot for loss and degradation of mangrove in the TBCA is Vanga in Kenya with a loss of 27 ha/yr. Harvesting of mangrove wood products have contributed to the loss of mangroves in the transboundary area. TBCA formation could play a critical role in ensuring sustainable mangrove resources utilization.

Phenology and floral synchrony of Rhizophora mangle along a natural salinity gradient

AbstractRhizophora mangle is the most common species of mangrove within its range and a major component of coastal ecosystems in the tropics and subtropics. Its phenology is affected by seasonal variations in temperature, salinity, and precipitation, all of which may be altered by impending climate change. In this work, the monthly leaf, flower, and fruit phenology of R. mangle was assessed at three sites, along a natural salinity gradient for 12 months. We assessed phenological states using litter traps installed in mangrove stands, and by direct observation of leaf production at two sites, and flower, and fruit production at a single site. Phenological events were compared with seasonal climatic variations (in wind, rain, and temperature) to explore potential abiotic controls on the phenology of this species. Leaf shedding was lowest at the low salinity site. Leaf and stipule production showed a seasonal trend, decreasing during the cool and dry winter months. Flowering was highly seasonal and synchronous and peaked during the rainy season. Flowering was correlated with average temperature (r = 0.82; p < 0.05) at all three study sites, but was not correlated with precipitation. At the high‐salinity site, flowering was restricted to the rainy season. Fruit abortion was associated with wind speed (r = 0.79; p < 0.05). Flowering of R. mangle is induced by increasing temperatures and the onset of rains. Rising temperatures, drier summers, and more frequent and intense storms, due to climate change, may influence mangrove productivity, population dynamics, and floral synchrony.

Stand dynamics and aboveground net primary productivity of a mature subtropical mangrove forest on Ishigaki Island, south-western Japan

There are insufficient data regarding forest productivity of mature mangroves near the northern limit of mangrove distribution in subtropical East Asia. We conducted the present study to determine the stand dynamics and net primary production (NPP) of a mature mangrove forest on Ishigaki Island in south-western Japan over three successive years, using a large permanent plot. The two mangrove species present were Bruguiera gymnorrhiza and Rhizophora stylosa. The aboveground biomass in the plot was high, despite the high latitude (24 ∘29′N) of the site, gradually increasing from 158.4 Mg ha−1 to 164.6 Mg ha−1 over the three-year study period. This increase was attributable to an increase in the biomass of B. gymnorrhiza. The biomass of R. stylosa, however, decreased during the same period because of a threefold-higher mortality rate and a lower relative growth rate of this species compared with B. gymnorrhiza. The mangrove forest was in the late successional stage, following a pioneer R. stylosa forest that was widely distributed throughout the study plot as standing dead trees and logs. The aboveground NPP of the mangrove forest was 10.66 ± 1.46 Mg ha−1 y−1, partitioned into 3.10 ± 0.51 Mg ha−1 y−1 as woody NPP (net increase in aboveground woody parts, SI), and 7.56 ± 0.99 Mg ha−1 y−1as foliage NPP (litter production, including foliage and reproductive organs, Ln). The mature mangrove forest had a relatively low SI/Ln ratio (0.41 ± 0.03), although litter fall production was within the range previously recorded for mangroves. The lower woody NPP in the mature mangroves was due to the exclusion of R. stylosa once the stand was in a late successional stage dominated by B. gymnorrhiza.

Local Community’s Perception of Mangrove Change Impact on Their Socioeconomic Condition in Johor, Malaysia

Mangrove forests across the globe have experienced remarkable rapid reduction over the recent few couple of decades due to land use changes and socioeconomic factors. These phenomena also have an impact on the socioeconomic condition of the local communities. This study was carried out to determine the impacts of mangrove changes on local community’s socioeconomic condition at the surroundings of Sungai Pulai Mangrove area in southwest Johor, Malaysia. A total of 360 respondents were interviewed by using a questionnaire. The perceived impacts were both negative and positive. As negative impacts, the respondents perceived ‘species and habitat loss’ followed by ‘coastal erosion’, ‘reduction of mangrove production and income’, biodiversity threatened’, ‘increase of migrants’ and ‘increased risk of livelihood’. However, as positive impacts, they perceived ‘new infrastructure developed for useful purpose replacing mangroves’ followed by ‘improved communication system’ and ‘increased the overall quality of living standards. The study concluded that the mangrove change in the study area negatively affecting to their mangrove dependency for livelihood activities whereas positively improving their living quality.

Impact of Global Change on Nutrient Dynamics in Mangrove Forests

The cycling of essential nutrients is central to mangrove productivity. A mass balance shows that mangroves rely on soil ammonification, nitrification, and dissimilatory reduction to ammonium for available nitrogen. Mangroves are often nutrient limited and show tight coupling between nutrient availability and tree photosynthesis. This relationship and, thus, forest productivity can be disrupted by various disturbances such as deforestation, changes in hydrology due to impoundments, land-use change, increasing frequency and intensity of storms, increasing temperatures, increasing atmospheric CO2 concentrations, and a rising sea-level. Deforestation and hydrological changes are the most devastating to soil nutrient-plant relations and mangrove productivity. Land-use changes can result in positive and negative impacts on mangroves and can also results in increasing frequency of storms and intensity of storms. Increasing temperatures and atmospheric CO2 levels have an initially enhanced effect on mangroves and microbial transformation rates of nitrogen and phosphorus. The effects of rising seas are complex and depend on the local rate of sea-level rise, the soil accretion rate, the subsidence or uplift rate, and the tidal position. If mangroves cannot keep pace with a sea-level rise, seaward mangroves will likely drown but landward mangroves will expand and show enhanced growth and more rapid nutrient cycling if space permits.

Mangrove sediment carbon stocks along an elevation gradient: Influence of the late Holocene marine regression (New Caledonia)

Among blue carbon ecosystems, mangroves are very efficient in storing carbon in their sediments over decadal to millennial time scales. However, this ability varies with numerous parameters, including climate and sea-level variations. In New Caledonia, mangrove ecosystems develop in semi-arid conditions with a typical zonation: Rhizophora spp. colonize the seaward side of the intertidal area, while Avicennia marina develops at higher elevations, just below the salt-flat. Within this context, we determined both the quantity (organic carbon content and carbon stocks) and the characteristics (carbon over nitrogen ratios (C/N), stable carbon and nitrogen isotopes, radiocarbon age) of the organic matter stored beneath each mangrove stands. Carbon stocks were determined down to different limits with depth: approximate extension of the root systems, one-meter depth, and the hard substrate. Within the extension of the root systems, the sediment carbon stock was lower than 100 MgC ha−1 regardless of the mangrove species. This low value resulted directly from the dry climate that limits mangrove productivity. At depth beneath every zone, a buried layer enriched in mangrove-derived organic matter, with C/N values around 40 and δ13C values around −26‰ was observed. This layer likely resulted from a sea-level high stand during the late Holocene that allowed a long period of stability of the mangrove, slowly accumulating organic matter within the sediment. In this buried layer, the carbon stock was higher than in the upper sediment and reached up to 665, 255 and 300 MgC ha−1 in the salt-flat zone, the A. marina stand and the R. spp. stand, respectively. The highest stock, determined beneath the salt-flat, was suggested to be related to a period of sea-level stability that lasted ~3000 years, whereas beneath the other zones, which are at lower elevations, mangrove colonization was more recent and the sea-level was continuously decreasing till recently. Sea-level variations, and, specifically current sea-level rise, may strongly influence mangrove development due to their migration along the tidal elevation gradient to maintain the biotic conditions needed for their development.

CONFIRMATORY FACTOR ANALYSIS: FAKTOR-FAKTOR PENENTU AGRIBISNIS MANGGA DI KABUPATEN MAJALENGKA BERDASARKAN PENGUASAAN LAHANNYA

Mango farmers in Majalengka Regency who have narrow land tenure tend to market their mangrove production only to traditional markets. Even if they are able to improve their agribusiness behavior, even smallholder farmers should have the opportunity to market mango production to the modern market which includes supermarkets and exports that will increase farmers' income. The purpose of this paper are: 1) To analyze the characteristics of mango farmers in Majalengka Regency; and 2) Analyzing the determinants of mango agribusiness in Majalengka Regency based on their land tenure. The research method used survey techniques in Majalengka District as one of the centers of mango production in West Java. The sample of farmers determined using 130 stratification sampling techniques. Data analysis techniques carried out using descriptive statistical analysis, and confirmatory factor analysis. The results of the study show that the proportion of farmers with narrow land tenure is 43 people (33.08%) while 87 people (66.92%) are mango farmers who are cultivating medium and wide land. Farmers who have narrow land tenure have a more homogeneous age than farmers whose land area is medium and wide, but more heterogeneous in terms of mango farming experience. The level of education of farmers with narrow land is lower than that of farmers whose land area is medium and wide. Factors that determine mango agribusiness in Majalengka Regency for farmers with narrow mastery, all significant factors are social factors, economic factors, technological factors, resource factors, institutional factors and cultural factors. Whereas for farmers with medium and broad mastery, significant factors are social factors, technological factors, resource factors and institutional factors, while economic factors and cultural factors are not significant.

The Valuation of Mangrove Forest Economy of Community Development Program of Badak LNG

Mangrove forest is one of the resources that has important functions and roles in a single ecosystem. The utilization of mangrove forest also has a fairly high economic value. The existence of mangrove forest has several functions such as a media for mangrove crab cultivation, mangrove cultivation, diversification of mangrove products and mangrove tourism. Some of these benefits were introduced by CSR of Badak LNG program to society around the mangrove forest in Bontang City for the economic improvement of coastal communities by exploiting the existing mangrove potential. Thus, the aim of this study is to calculate the economic value of the utilization of mangrove forest. The research method used is quantitative method by using benefit cost analysis. In brief, the results showed that the utilization of mangrove resources conducted by the community or local community groups such as mangrove crab cultivation, mangrove seedling, mangrove dodol, mangrove syrup and mangrove tourism. The highest direct benefits of mangrove area came from mangrove seedlings (71%), mangrove dodol (9.76%), mangrove tourism (6.82%), mangrove crab (6.47%) and mangrove syrup (5.96 %). Meanwhile the value of choice for mangrove area is 30 Ha. From the calculation results, the benefit obtained of mangrove forest selection was Rp 6.087.150,00 per year. Based on the mentioned value, it indicated that the respondents were willing to pay for the existence of mangrove forest ranging from Rp 50.000,00 – Rp 750.000,00. The total existence value of mangrove forest was Rp 4.375.000,00 for 50 respondents and the total value of existence per year was Rp 52,500,000.00. The total benefit of mangrove forest was Rp 4,749,322,671,00 per year. As the result, the 87% indirect benefit is the largest contributor to the benefits of mangrove forests in South Bontang District. While the second largest contributor is a direct benefit of 12%.

Mangrove carbon assessment tool: Model development and sensitivity analysis

It is important to have the capability to assess carbon (C) dynamics in mangrove forests and estimate their role in mitigating climate change because of their high carbon density, the threats to their integrity from land-use change and sea-level rise, and functional linkages of the many goods and services. A process-based model for mangroves was developed by integrating new features with existing biogeochemical processes in Forest-DNDC for simulating C sequestration and turnover in mangrove ecosystems. The new model is used to assess (1) the dynamics of C, nitrogen and phosphorous in mangrove ecosystems, including above-and below-ground C in saline wetlands, (2) the impacts of ecological drivers, including climate, soil nitrogen and phosphorous deficit and salt stress, on mangrove production, (3) the production of methane, and aerobic and anaerobic oxidation of methane with sulfate, nitrate and nitrite reductions, (4) the contributions of dissolved inorganic C (DIC), dissolved organic C (DOC), particulate organic C (POC) and burial C (BC) to blue C, and (5) impacts of natural and anthropogenic disturbances on C sequestration in mangrove ecosystems. Model sensitivity analysis showed that C sequestration in mangrove ecosystems was highly sensitive to multiple ecological factors, including climate, soil phosphorus, salinity and sulfate, as well as latitude. The responses of different C components to these factors were distinct. The responses of gross and net primary productivity and aboveground biomass to alterations of mean daily temperature (MDT) were quadratic, or increasing or decreasing non-linearly with an increment or decrement in MDT, but leaf production was linear. Similarly, other mangrove C components, such as BC, DIC, DOC and POC, respond substantially to variations of the ecological drivers. The combined effects of the driving factors are complex due to their intricate interactions. For example, while mangrove productivity is sensitive to available phosphorous, phosphorous cannot mitigate the stress imposed by high salinity. These results highlight the value of a tool to assess C dynamics in mangroves, especially for regional or large mangrove forests.

The sources and distribution of carbon (DOC, POC, DIC) in a mangrove dominated estuary (French Guiana, South America)

Mangrove forests are highly productive coastal ecosystems that significantly influence global carbon cycling. This study characterized the sources of dissolved organic carbon (DOC), particulate organic carbon (POC) and dissolved inorganic carbon (DIC) and the processes affecting their distributions in a mangrove-influenced estuary located in French Guiana (FG), a region representative of these dynamic systems down drift of the Amazon River. Four sampling cruises were carried out between 2013 and 2015 in surface waters of the estuary during dry and wet seasons. Stable isotopes (δ13DOC, δ13POC, δ13DIC), elemental ratios and optical properties (absorption) were used as proxies to identify different C sources. Property–salinity relationships revealed regions of approximately linear mixing (e.g., alkalinity) or net sources or sinks (e.g., DOC). DIC speciation and isotopic distributions demonstrated dynamic source–sink reaction processes within the estuary. DOC was the major form of organic carbon representing mixtures of terrestrial sources (e.g., pore water, litter leaching) and very high concentration (400–800 µM) compared to other mangrove settings (e.g. Brazilian, Sundarbans, African). Highly negative δ13POC (− 40‰) in the riverine part presumably suggests the role of freshwater phytoplankton in the dry season and methanotrophic sources derived from senescent mangrove deposits or upstream hydrothermal dam during the wet season. Microphytobenthos and marine phytoplankton were the primary sources of POC inshore and DOC offshore, respectively. Mangrove products and benthic microalgae dominated estuarine sources of C in FG coastal waters (~ 10 km, inner shelf region), and there was extensive exchange of C between forest and tidal flat and the estuarine reservoirs.

Produksi Pangan Fungsional Alternatif Olahan Mangrove di Kabupaten Purworejo

Currently, the potential development of alternative functional food comes from various types of leaves and mangrove fruit. One of the coastal areas that have a potential mangrove area is Gedangan Village, Purwodadi District, Purworejo Regency, Central Java. The purpose of this program was to the utilization of mangrove into processed functional food as an effort to improve the economy and environmental conservation through creative small industries that utilize the natural potential. Outcomes of this IbM program were CASEOLARIS of mangrove syrup, JERUJU of mangrove tea and FRUTICA mangrove fruit sweets. Mangrove products were potentially to be developed in Purworejo

Structural characteristics, above‐ground biomass and productivity of mangrove forest situated in areas with different levels of pollution in the Niger Delta, Nigeria

AbstractProductivity is a major driver of carbon sequestration in mangrove ecosystems worldwide. It is hypothesized that hydrocarbon pollution can accelerate litter fall and increase productivity through detoxification. We studied structural characteristics, above ground biomass (AGB) and productivity of mangroves in higher and lower polluted locations in the Niger River Delta, Nigeria. We established four 400 m2 plots in a random block design to test the effects of pollution on mangrove productivity. A total of 1,089 mangrove tree structural characteristics and importance values (IV) were estimated. For productivity, ten litter traps (0.1521 m2) were established within each plot, and emptied monthly for three years, June 2010 – June 2013. Total productivity was significantly different between treatments (F1, 1378 = 9.673, p < .001), with highly polluted having higher total productivity. Flowers (F1, 1378 = 9.673, p < .001) and fruits (F1, 1378 = 9.673, p < .001) productivity varied between treatments too, again with the highly polluted being significantly greater. Our results indicate that pollution increased litter fall, and thus altered productivity in the Niger Delta mangrove. To the best of our understanding, this is the first time productivity has been reported in the primary literature for the Niger Delta mangrove ecosystem.

Drivers of mangrove ecosystem service change in the Sundarbans of Bangladesh

Mangroves are now well known to provide a range of ecosystem services that benefit local populations, though such ecosystem services are at risk from mangrove deforestation and degradation across much of the tropics. This study aimed to identify the natural and anthropogenic drivers of change that affect ecosystem services of the Sundarbans mangrove forest. Secondary data analysis and primary fieldwork were conducted in three districts in the Sundarbans region of Bangladesh to understand ecosystem service usage and the perceptions of local resource users. Time series data for a range of ecosystem services and biophysical, socio‐economic variables were analyzed to identify the range of trends and the significant drivers of change. Also, community perceptions were consulted to elicit how these changes are felt and how they affected the local ecosystem services users. Results show that most of the ecosystem services of the Sundarbans experienced negative changes over the last two decades. Time series analysis and community perceptions held a number of drivers responsible for these changes. Climatic change, rapid environmental change, demand for mangrove products on the global market, major infrastructure development and governance failure were identified as primary drivers leading to the degradation of ecosystem services of the Sundarbans. The study calls for a transformation in the stewardship of ecosystem services of the Sundarbans and other mangroves across the tropics, to escape the situation where negative environmental impacts might be difficult to reverse.

Mangrove Productivity and Phenology in Relation to Hydroperiod and Physical–Chemistry Properties of Water and Sediment in Biosphere Reserve, Centla Wetland, Mexico

Mangrove is the dominant vegetation in the estuaries, river deltas, and coastal lagoons of tropical and subtropical regions. A number of factors affect the structure and productivity of mangrove forests, including hydrology, soil salinity, and soil type. In this study, litter production in the Centla Wetland Biosphere Reserve in Tabasco, Mexico, was evaluated as a function of the physical–chemical properties of water and sediments. The study cycle was from June 2015 to June 2016. Litterfall was measured, and water samples were collected at the surface, interstitial, and subterranean level to estimate the physical–chemical parameters. Sediment samples were also collected to determine the texture, pH, organic matter, bulk density, and moisture content. The mangrove was composed of Rhizophora mangle (L.), Laguncularia racemosa (L.) Gaertn, and Avicennia germinans (L.) Stearn. The pH was presented in a range of 5.3 to 7.4, and spatially, the texture of sediment varied significantly, with high values of sand in Playa (73.7% ± 3.4%) and high content of clay (57.2% ± 1.4%) and organic matter (41% ± 2% average) in mangrove riverine type. The highest salinity of interstitial water was encountered at Beach (29 ± 3.0 PSU) and of groundwater (36.4 ± 1.5 PSU). Overall, the average estimated litter fall was 10.45 ton·ha−1·year−1. These results indicate that the litter production is related to the response of the mangrove to the variation of the environmental conditions of each site (substrate texture, hydroperiod, soil moisture, water salinity, water redox potential, and soil organic matter).

Community Knowledge Related to Mangrove Conservation Law Products

Indonesia is a country that has an area of mangrove forests in the second place of the world. East Java is one of the provinces that have mangrove forests. The mangrove forest has various conditions, not only good conditions but also damaged conditions. The main cause of damage is the conversion of mangrove forests to ponds and the use of mangrove wood as charcoal. Mangrove forest has various functions so that the Indonesian government issues various laws and regulations relating to the preservation of mangrove forests. This study uses a qualitative approach. Data were collected by in-depth interviews and observations. The informants taken were people who lived around the mangrove area. The study location is on the north coast of East Java which includes Lamongan Regency, Gresik Regency, Pasuruan Regency, and Probolinggo Regency. The results of the study show that the majority of people know the mangrove conservation law products. Community knowledge is mainly obtained from the Village Head. Moreover, they do not know the types of law violations or types of law enforcement related to mangrove conservation. People living in mangrove areas know that there are regulations about mangrove forests, even though they do not know the substance.

Life Cycle Assessment of Secondary Mangrove Forest in Bintuni Bay,West Papua, Indonesia

The life cycle assessment is conducted in order to assess the impact of mangrove woodchip production in Bintuni bay, West Papua Indonesia on the environment. Study includes the analysis of non-renewable energy use (MJ), global warming potential or carbon footprint (kg CO2), acidification potential (kg SO2) and ozone creation potential (kg O3) of mangrove logging, processing and shipment. Mangrove woodchip production consumes 960 MJ of non-renewable energy and gives out 59.59 kg CO2, .383 kg SO2 and 30.39 kg O3, which is the lowest in comparison with other wood products. Mangrove processing incur less fuel because it is delivered in bulk to the processing area via barges in comparison to other wood products The current shipping of mangrove woodchips to customers has the greatest environmental impact because of the use of bunker fuel. The processing of mangrove woodchips used diesel exclusively for fuel in its power sources. Forest residues from logging can be a source of renewable fuel and may also be another source of new products.

The economic value of fisheries harvest supported by saltmarsh and mangrove productivity in two Australian estuaries

Broad-scale links between productivity of estuarine habitats (such as saltmarsh and mangrove) and the exploited species that rely on them have often been used to build a case for habitat conservation and repair. Stable isotope composition can provide a temporally and spatially integrated measure of trophic connectivity with which to quantify habitat-fishery linkages, allowing primary producers that comprise these habitats to be linked with harvested biomass with relatively few assumptions. We present a novel model that applies this approach to estimate the economic value of fisheries harvest derived from dominant estuarine habitats, in two eastern Australian estuaries. Estimated values of fisheries harvest supported by habitats within the model regions ranged from ∼AUD100,000y−1 to ∼AUD7,200,000y−1. Saltmarsh in the Clarence River had by far the greatest economic value per-unit-area, with an average estimated Total Economic Output (from fisheries harvest) of AUD25,741ha−1y−1, whereas mangrove was estimated to be AUD5,297ha−1y−1. Average Total Economic Output in the Hunter River was AUD2,579ha−1y−1 and AUD316ha−1y−1 for saltmarsh and mangrove habitats respectively. Estuarine habitats are key ecological indicators of fisheries productivity, and the framework presented here will be broadly useful in estimating the potential economic impacts associated with changes in these indicators.

Producción de hojarasca y atributos estructurales del manglar en la Laguna Mecoacán, Golfo de México.

Abstract: Mangroves are tropical species established along topographic gradients in coastal areas, where variations in salinity and flooding periods influence the composition and characteristics of primary productivity. In this paper the structural attributes and litter production of mangroves of the Mecoacan lagoon, Gulf of Mexico were evaluated. In six monitoring sites the floristic composition, diameter at breast height (DBH), height, density mature mangrove trees, juveniles, recruits and seedlings, extraction and mortality were determined. Besides, basal area, importance value index (IVI), coverage and Holdridge complexity index, were calculated. Productivity litter of different mangrove species was quantified by trapping capture, while the physico-chemical parameters in surface, interstitial and groundwater were determined by installing piezometers. The study sites in Mecoacan lagoon were classified into two physiographic types: fringe (Boca, Aspoquero, Arrastradero and Pajaral) and basin (Cerros and Mojarrero). 2 854 mature mangrove trees were measured, where 93% belonged to living trees, 4.4% of extracted trees, and 2.6% dead trees standing. The average density was 2 870 mature mangrove trees ha-1. The highest basal area was found in Pajaral (41.7 m-2 h-1). Avicennia germinans (L.) Stearn presented IVI values higher everywhere, for its high relative density. An average cover of 17.5 m2 was registered. The highest rate in complexity was registered in Cerros (27.5). The species showed zonation with salinity levels of interstitial water; A. germinans located in areas of high salinity (hypersalines) while Laguncularia racemosa (L.) Gaertn and Rhizophora mangle L. in areas of lower salinity. Litter production was 5.15 t ha-1 yr-1, it showed a positive correlation with rainfall and high negative correlation with salinity levels and ORP interstitial and groundwater. Results indicate that variability in the composition and structure of mangrove the Mecoacan, is locally determined by the ability to adapt to environmental conditions (salinity, redox potential) and interspecific relationships of the species present.