Km-2 Year-1 Research Articles

From invaders to residents: The golden jackal (Canis aureus) expansion in Hungary since the mid-1990s.

The golden jackal has rapidly expanded across Europe in recent decades and was one of the first to reappear in Hungary. Using hunting bag data from the National Game Management Database from 1995 to 2021, we examined the spatial expansion of the species and its population dynamics. Our findings reveal an exponential increase in the golden jackal population since the mid-1990s, with an average annual growth rate of 40% in the hunting bag and an occupancy of 86% of the country. The average speed of the range expansion was 536.9 km2 year-1 until 2007 and increased to an average of 5,289.1 km2 year-1 during the second part of the expansion process. The density of shot golden jackals also shows an increasing trend with a substantial presence of outliers, indicating that nearly 10% of the hunting bag demonstrates exceptionally high numbers, particularly in southwestern Hungary. The spread originated in the southwest and extended towards the northeast and northwest. However, the increase of the hunting bag slowed down and the expansion rate has decreased in the previous two years, leading us to anticipate that the golden jackal population will stabilize soon, as the expansion has reached its maximum in Hungary. This indicates that from the initial settlement to the stabilization of the population, the time span can be two to three decades.

Including Methane Emissions from Agricultural Ponds in National Greenhouse Gas Inventories.

Agricultural ponds are a significant source of greenhouse gases, contributing to the ongoing challenge of anthropogenic climate change. Nations are encouraged to account for these emissions in their national greenhouse gas inventory reports. We present a remote sensing approach using open-access satellite imagery to estimate total methane emissions from agricultural ponds that account for (1) monthly fluctuations in the surface area of individual ponds, (2) rates of historical accumulation of agricultural ponds, and (3) the temperature dependence of methane emissions. As a case study, we used this method to inform the 2024 National Greenhouse Gas Inventory reports submitted by the Australian government, in compliance with the Paris Agreement. Total annual methane emissions increased by 58% from 1990 (26 kilotons CH4 year-1) to 2022 (41 kilotons CH4 year-1). This increase is linked to the water surface of agricultural ponds growing by 51% between 1990 (115 kilo hectares; 1,150 km2) and 2022 (173 kilo hectares; 1,730 km2). In Australia, 16,000 new agricultural ponds are built annually, expanding methane-emitting water surfaces by 1,230 ha yearly (12.3 km2 year-1). On average, the methane flux of agricultural ponds in Australia is 0.238 t CH4 ha-1 year-1. These results offer policymakers insights into developing targeted mitigation strategies to curb these specific forms of anthropogenic emissions. For instance, financial incentives, such as carbon or biodiversity credits, can mobilize widespread investments toward reducing greenhouse gas emissions and enhancing the ecological and environmental values of agricultural ponds. Our data and modeling tools are available on a free cloud-based platform for other countries to adopt this approach.

PISCINE BIODIVERSITY CHARACTERIZATION OF THE STUBBS CREEK, NIGER DELTA, NIGERIA RECEIVING OIL SPILL EFFLUENTS

A parsimonious survey of the fish biodiversity of the Stubbs Creek, a coastal freshwater/ blackwater stream in the Niger Delta, Nigeria was conducted. The all Teleostei fishes comprised a high taxonomic heterogeneity with 32 species, 24 genera and 17 families. They were organized in three eco physiological assemblages (the primary freshwater, secondary freshwater and peripheral Assemblages) and four mesohabitat assemblages (benthic, benthopelagic, pelagic and epipelagic assemblages). Approximately 84.4% of the fish species were found to be equipped with a variety of biophysical life enhancement devices which enable them to optimally exploit the available resources of the habitat space. The Stubbs Creek has the potential of producing about 27.2 tonnes km-2 year-1 of fish flesh for human consumption, barring the impacts of oil spill effluents from a major oil producing company within the Stream basin/catchment area. Elevated levels of Hydrocarbon (PAHs) and heavy Metals, far above WHO recommended levels were observed in this study. It is figured that the results of this study qualify the Stubbs Creek to be considered as ‘Stream of Special Scientific Interest‘ (SSSI) for management and conservation purposes

Trophic functioning of a small, anthropogenically disturbed, tropical estuary

A trophic model was constructed for the Poonthura Estuary, a small, anthropogenically impacted estuary along the south-western coast of India. An Ecopath with Ecosim based trophic modelling approach, based on observations made between 2016 and 2020, revealed that the Poonthura Estuary had a low total system throughput (3044.2 t km-2 year-1), low ascendancy (15%), high Finn’s cycling index (17.9%), low primary production/total biomass (5.2 t km-2 year-1), high mean transfer efficiency (12.4%), and low eco-exergy (14,455.46 gm detritus equivalent m-2). These values indicated that the estuary is an immature, less organized, and unhealthy system. The evaluation of Ecological Network Analysis, and ecosystem health indices revealed that the ecological structure and functioning of the estuary are impaired to a large extent from multiple anthropogenic stressors. The Poonthura Estuary trophic model revealed the total primary production/respiration value as 0.46, indicative of the massive pollution that the system is subjected to, particularly from organic sources. Small benthic carnivores were the most important keystone groups recorded from the Poonthura Estuary, despite their low biomass. The comparison of ecological indices of Poonthura Estuary, with those recorded for other small estuaries from various geographical locations, suggested dissimilar trophic functioning and food web structures from estuaries with similar physical features. Our study is a pioneering step to reveal the ecosystem status and functioning of small, anthropogenically disturbed estuaries, besides offering theoretical and scientific basis for the management, supervision and restoration of the Poonthura Estuary as well as other small estuaries, around the world.

Historical evolution of gully erosion and its response to land use change during 1968–2018 in the Mollisol region of Northeast China

Gully erosion is one of the most severe types of land degradation, hindering food production and sustainable agricultural development. However, the historical evolution process and the impact of land use change on gully erosion remain unclear. To address this issue, we conducted a field investigation on gully erosion in 2018 and interpreted land use and gullies using historical remote sensing images in 1968 and 1978 over an area of 84.48 km2. The study found that from 1968 to 1978 to 2018, all gully morphological parameters including gully length density and gully areal density increased significantly. The main origin of gully erosion found was from dry farmland. The annual soil loss rate induced by gully erosion was 1.46 mm during 1968–2018. Gully erosion rates were higher during 1968–1978 than during 1978–2018. Furthermore, the length, areal and volumetric erosion rates in gullies formed by multiple gullies merging was greater than that of newly formed gullies (NFG) and gullies developing continuously from a single pre-existing gully, while the widening rate of NFG was highest. The susceptibility of land use types to gully erosion was in the order of woodland < dry farmland < degraded land. The annual average increase in gully area was 871.09 m2 km-2 year-1 for parcels that were converted from woodland to dry farmland, which was 5.56 times and 1.78 times greater than that of woodland and dry farmland maintenance, respectively. Therefore, urgent implementation of ecological land use plans and gully erosion control practices is suggested for this region.

Trophic fingerprinting of a pristine but rapidly deteriorating downstream region of a Western Ghats River.

Chalakudy River is renowned for its pristine waters and rich ichthyofaunal biodiversity. The downstream area of the river is confronting a series of risks, including pollution, saline water ingression, sand mining, illegal and intensified fishing practices, and invasion of exotic and alien species. A mass balanced ecosystem model was constructed for the downstream region of Chalakudy River (DCR) using Ecopath with Ecosim (EWE), incorporating 12 functional groups to delineate the food web and network flow indices for the period 2020 to 2021. The trophic level (TL) of the ecosystem network ranged from TL-1 (detritus) to TL-3.4 (birds). High fishing pressure is one possible cause for the high ecotrophic efficiency values as evidenced by the fish groups. Both the grazing food chain and detritus food chain (detritivory: herbivory ratio 0.94) contributed more or less equal to the energy transfer between TL. Network analysis of the model indicated a mean transfer efficiency of 12%, with shares from primary producers (14%) and detritus (11%). A mixed trophic impact analysis demonstrated a strong positive impact of primary producers and detritus groups on most of the other ecological groups at higher trophic levels. The DCR model showed a high system throughput (32,464.7 t km-2 year-1), low system omnivory (0.09), low connectance index (0.36), low Finn's cycling index (4.9), and mean path length (2.8), low relative ascendency (37.5%), and high system overhead (62.5%). These indices propound that DCR is an immature and developing ecosystem with moderate strength in reserve to resist external perturbations.

Spatiotemporal Dynamic of Land Use/Land Cover Changes and Their Drivers in the Fincha&amp;#39; a-Neshe Sub-Basin, Southeastern Blue Nile Basin, Ethiopia

It is paramount to evaluate the spatiotemporal dynamics of land use and land cover (LULC) changes and their drivers. This is because it helps generate information on biodiversity, land productivity, ecology, and livelihoods for decision-making. Due to land degradation, deforestation, shifting cultivation, high population pressure, and the three national megaprojects (NMPs), the Fincha&amp;#39;a Neshe sub-basin (FNSB) LULC, changes may be unprecedented. This study aimed to investigate the spatiotemporal dynamics of LULC changes and their drivers using remote sensing (RS) data and geographic information systems (GIS). Landsat images 5, 7, and 8 were used for the discrete periods of 1986, 2000, and 2016, respectively. Field observations (Ground control points) and interviews were conducted with key participants to validate the data. Supervised classification with a maximum likelihood algorithm was used to classify the Landsat imagery. The results showed that the FNSB experienced substantial changes in LULC between 1986 and 2016, of which 13.8% (457.3 km2 ) were due to NMPs. The cropland cover has expanded by 694.4 km2 (57.81%) at a rate of 24.60 km2 year-1 at the expense of shrubland, forest, wetland, and grassland. In contrast, shrubland, forest, wetland, and grassland have declined at the rates of 16.8, 3.9, 3.4, and 1.7 km2 year-1 over the entire study period. Population growth and NMPs were the principal drivers of the changes in the LULC of the sub-basin. Thus, the LULC transformation rate observed in the sub-basin requires due attention and mitigation strategies, as it might seriously threaten the sustainability of natural resources and NMPs.

Long-term dense Landsat observations reveal detailed waterbody dynamics and temporal changes of the size-abundance relationship

Study regionSurface water bodies in Hunan Province, China. Study focus:Surface water bodies (WB) are important for agriculture, aquiculture, and aquatic and terrestrial ecosystems, yet monitoring and understanding the spatiotemporal dynamics of water bodies over large areas remain a major challenge. This study used all the available Landsat images and the Google Earth Engine (GEE) to map and analyze annual changes of all water bodies (>0.001 km2) in Hunan Province, China, from 1987 to 2020. New hydrological insights for the region:A total of 76,928 WBs were detected with a total area of 4181.14 km2 (both were averages during the study period) with an interannual variability of − 117 and − 20.05 km2 year-1, respectively. Surface areas of small (0.001–1 km2), medium (1–50 km2), and large (>50 km2) WBs changed at various rates and directions. The size-abundance relationship of WBs followed the power scaling law with a positive trend in the scaling exponent, implying the fraction of small WB number has decreased over the past three decades. The temporal change of the size-abundance relationship, reflects the strong and dynamic imprints of both human activities and regional climate change. Future research should strive to understand the temporal change of the size-abundance relationship of WBs as it is important for water resources management and estimating the temporal changes of greenhouse gas fluxes from WBs over large areas.

Impacts of the 2012-2015 Californian drought on carbon, water and energy fluxes in the Californian Sierras: Results from an imaging spectrometry-constrained terrestrial biosphere model.

Accurate descriptions of current ecosystem composition are essential for improving terrestrial biosphere model predictions of how ecosystems are responding to climate variability and change. This study investigates how imaging spectrometry-derived ecosystem composition can constrain and improve terrestrial biosphere model predictions of regional-scale carbon, water and energy fluxes. Incorporating imaging spectrometry-derived composition of five plant functional types (Grasses/Shrubs, Oaks/Western Hardwoods, Western Pines, Fir/Cedar and High-elevation Pines) into the Ecosystem Demography (ED2) terrestrial biosphere model improves predictions of net ecosystem productivity (NEP) and gross primary productivity (GPP) across four flux towers of the Southern Sierra Critical Zone Observatory (SSCZO) spanning a 2250m elevational gradient in the western Sierra Nevada. NEP and GPP root-mean-square-errors were reduced by 23%-82% and 19%-89%, respectively, and water flux predictions improved at the mid-elevation pine (Soaproot), fir/cedar (P301) and high-elevation pine (Shorthair) flux tower sites, but not at the oak savanna (San Joaquin Experimental Range [SJER]) site. These improvements in carbon and water predictions are similar to those achieved with model initializations using ground-based inventory composition. The imaging spectrometry-constrained ED2model was then used to predict carbon, water and energy fluxes and above-ground biomass (AGB) dynamics over a 737km2 region to gain insight into the regional ecosystem impacts of the 2012-2015 Californian drought. The analysis indicates that the drought reduced regional NEP, GPP and transpiration by 83%, 40% and 33%, respectively, with the largest reductions occurring in the functionally diverse, high basal area mid-elevation forests. This was accompanied by a 54% decline in AGB growth in 2012, followed by a marked increase (823%) in AGB mortality in 2014, reflecting an approximately 10-fold increase in per capita tree mortality from ~55 treeskm-2 year-1 in 2010-2011, to ~535 treeskm-2 year-1 in 2014. These findings illustrate how imaging spectrometry estimates of ecosystem composition can constrain and improve terrestrial biosphere model predictions of regional carbon, water, and energy fluxes, and biomass dynamics.

Lightning Climatology and Human Vulnerability to Lightning Hazards in a School Community: A Case Study in Sri Lanka using LIS Data from TRMM Satellite

This study reported lightning climatology and human vulnerability to lightning in a 20 km × 20 km high-density school area in Colombo city in Sri Lanka from 1998 to 2014 using Lightning Imaging Sensor (LIS) flash data of NASA’s Tropical Rainfall Measuring Mission (TRMM). An average annual flash density recorded over the study area was 9.43 flashes km-2 year-1. A maximum of 49% lightning flashes happened during the first inter-monsoon season. There were only 4% lightning flashes that occurred during 06.00-12.00 LT and during 18.00-24.00 LT, it was 67%, whereas 94% of lightning flashes within a day had occurred after 14.00 LT. It is recommended that, without having proper lightning hazard preventive measures, schools in the study area should avoid or minimalize scheduling their outdoor activities in high lightning risk months of April and November. Especially, after-school outdoor activities should be planned with proper safety measures during the aforementioned months as per the diurnal analysis. Moreover, May to September and December to February were the months with the least lightning risk levels. It is recommended to follow the proposed five-level lightning safety guideline which includes, schedule outdoor activities by considering the variation of lightning activities, follow the 30-30 rule whenever required, avoid staying at the most hazardous locations which are vulnerable to lightning accidents, crouching action if required and providing first-aid whenever necessary. Not only for the Sri Lankan context but also the study is crucial and highly applicable for all schools and other institutes especially in other tropical countries.

Climatology of Lightning Activities over Bandaranaike International Airport in Sri Lanka

This study reveals the spatiotemporal distribution of lightning activities over Bandaranaike International Airport, the main international airport of Sri Lanka. Lightning flash data was acquired from the Lightning Imaging Sensor (LIS) on Tropical Rainfall Measuring Mission (TRMM) of NASA to investigate lightning activities from 1998 to 2014 covering an area of 30 km×30 km over the airport. Overhead annual flash density was 8.19 flashes km-2 year-1. The maximum lightning activities (57%) with an overhead flash density of 28.83 flashes km-2 year-1 was recorded in the first inter-monsoon season. The overhead flash density of 5.28 flashes km-2 year-1, 16.36 flashes km-2 year-1 and 7.46 flashes km-2 year-1 were recorded in the southwest monsoon season, second inter-monsoon season, and northeast monsoon season respectively. The month of April accounts for the highest number of lightning activities while maximum lightning flashes (22%) had occurred during 19.00-20.00 Local Time. According to the international climate season, maximum lightning activities over the study area have been recorded from March to May and during this seasonal period, the northern hemisphere is in spring and the southern hemisphere is in autumn. Safety guidelines are proposed to minimize lightning accidents in the airport. It is important to concern the regions with high lightning activity and vulnerable time periods to mitigate lightning accidents and to take adequate safety precautions to ensure the safety of passengers and the working crew to achieve environmental goals of sustainable development in the aviation industry.

Modeling Riverine N2O Sources, Fates, and Emission Factors in a Typical River Network of Eastern China.

Estimates of riverine N2O emission contain great uncertainty because of the lack of quantitative knowledge concerning riverine N2O sources and fates. Using a 3.5-year record of monthly N2O measurements from the Yongan River network of eastern China, we developed a mass-balance model to address the riverine N2O source and sink processes. We achieved reasonable model efficacies (R2 = 0.44-0.84, Nash-Sutcliffe coefficients = 0.40-0.80) across three tributaries and the entire river system. Estimated riverine N2O loads originated from groundwater (38-88%), surface runoff (3-26%), and in-stream production (4-48%). Estimated in-stream losses via atmospheric release + complete denitrification accounted for 76, 95, 25, and 89% of riverine N2O fate for the agricultural, residential, forest, and entire river system, respectively. Considering limited complete denitrification, the model estimated an upper-bound riverine N2O emission rate of 2.65 ton N2O-N km-2 year-1 for the entire river system. Riverine N2O emission estimates were of comparable magnitude to those estimated with a power-law scaling model. Riverine N2O emissions using the IPCC default emission factor (0.26%) overestimated emissions by 3-15 times, whereas the dissolved N2O concentration-based emission factor overestimated or underestimated emissions. This study highlights the importance of combining comprehensive information on N2O sources and fates to achieve accurate riverine N2O emission estimates.

Valuation of kelp forest ecosystem services in the Falkland Islands: A case study integrating blue carbon sequestration potential

Kelp forests provide many important ecosystem services to people, including mitigating storm damage, cycling nutrients, and providing commercially-harvestable resources. However, kelp forests’ ability to sequester carbon dioxide, and therefore help regulate the climate, has until recently, been overlooked in assessments of the beneficial services they provide. In this study we incorporate updated knowledge on the potential of kelp to sequester ‘blue carbon’, and use the extensive kelp forests of the Falkland Islands as a case study to assess the value of kelp forest to society through multiple associated ecosystem services. Our analysis shows kelp forests provide a highly valuable range of direct and indirect services, which if managed correctly, will continue to benefit people, both now and in the future. The total estimated value of the Falkland Islands’ kelp system is currently equivalent to ~ £2.69 billion per year (or £3.24 million km-2 year-1). However, the true value of the kelp forest surrounding the Falkland Islands is likely to be higher still, given that our estimate does not account for elements such as associated scientific research, tourism, and cultural services, due to the necessary data currently being unavailable. Similarly, the full value of these highly biodiverse ecosystems in supplying habitat and food to a large range of associated species is crucial, yet extremely difficult to fully quantify. This study illustrates the importance of maintaining kelp ecosystems in a healthy state to ensure they continue to supply valuable ecological processes, functional roles, and ecosystem services, including their overlooked role as significant long-term carbon sinks.

Ecosystem health status and trophic modeling of an anthropogenically impacted small tropical estuary along India's west coast.

The tropical estuaries are characterized with high biological production and also impacted by anthropogenic activities. Describing these estuaries in terms of ecological data and trophic dynamics to reveal the ecological impacts is gaining attention recently. In this study, the ecological structure is analyzed for a heavily impacted small macrotidal tropical estuary, Ulhas river estuary (URE), situated near Mumbai megacity in the western coast of India, to delineate the impact of anthropogenic stressors on the ecosystem functioning. The URE is being exploited for sand and fisheries resources, and also faces risks from anthropogenic activities. The ecological data of URE were compiled for 2017-18 together with the most relevant literature estimates to construct an ecosystem model. A trophic organization in 20 functional groups was identified for URE using Ecopath modeling approach. The functional groups identified in the food web ranged from detritus and primary producers (trophic level (TL) = 1) to large pelagics (TL = 4.14). Detritivory: herbivory ratio (1.35) indicated that the detritus chain is dominant over the primary producer's chain. The total system throughput (TST) was estimated as 16 736.2 t km-2year-1. The indices such as net system production (NSP = 1 398.781 t km-2 year-1), total primary production/total biomass (TPP/TB = 25.17), biomass/total system throughput (TB/TST = 0.01), recycling index (Finn's Cycling Index = 13.94%), system omnivory index (0.3), relative ascendency (25.6%), and system overhead (74.4%) classified URE as an immature system. The eco-exergy index (30748.54 gm detritus equivalent m-2) showed that the ecosystem is a moderately stable and relatively less organized network. The estuarine fish community index (EFCI) yielded a value of 38 indicating the poor health status of the fish community in URE. The study delivers a comprehensive understanding of the ecosystem setting in URE and characterizes the prevailing condition. The ecological indicators analyzed here point towards a medium to a high level of impact in URE due to anthropogenic activities.

Isolating Anthropogenic Wetland Loss by Concurrently Tracking Inundation and Land Cover Disturbance across the Mid-Atlantic Region, U.S.

Global trends in wetland degradation and loss have created an urgency to monitor wetland extent, as well as track the distribution and causes of wetland loss. Satellite imagery can be used to monitor wetlands over time, but few efforts have attempted to distinguish anthropogenic wetland loss from climate-driven variability in wetland extent. We present an approach to concurrently track land cover disturbance and inundation extent across the Mid-Atlantic region, United States, using the Landsat archive in Google Earth Engine. Disturbance was identified as a change in greenness, using a harmonic linear regression approach, or as a change in growing season brightness. Inundation extent was mapped using a modified version of the U.S. Geological Survey’s Dynamic Surface Water Extent (DSWE) algorithm. Annual (2015–2018) disturbance averaged 0.32% (1095 km2 year−1) of the study area per year and was most common in forested areas. While inundation extent showed substantial interannual variability, the co-occurrence of disturbance and declines in inundation extent represented a minority of both change types, totaling 109 km2 over the four-year period, and 186 km2, using the National Wetland Inventory dataset in place of the Landsat-derived inundation extent. When the annual products were evaluated with permitted wetland and stream fill points, 95% of the fill points were detected, with most found by the disturbance product (89%) and fewer found by the inundation decline product (25%). The results suggest that mapping inundation alone is unlikely to be adequate to find and track anthropogenic wetland loss. Alternatively, remotely tracking both disturbance and inundation can potentially focus efforts to protect, manage, and restore wetlands.

Variability of Soil Erosion Intensity Due to Vegetation Cover Changes: Case Study of Orahovacka Rijeka, Montenegro

Vegetation cover change in all the river basins leads to the changes of hydrologic response, soil erosion and sediment dynamics characteristics. Those changes are often viewed as main cause of anthropogenic and accelerated erosion rates in short term and one of the main reasons of climate change in long term. The effects of vegetation cover changes on various parts of water balance and hydrological cycle has to be deeply studied because of its important role on mankind future. The aim of present research was therefore to simulate the responses of soil erosion processes by using a process-oriented soil erosion model IntErO, with the different settings of land use for the years 1977, 1987, 1997, 2006 (2007) and 2016 (2017) in Orahovacka Rijeka watershed; a pilot river basin of the Polimlje Region for the northeastern part of Montenegro. For the current state of land use, calculated peak discharge for the Orahovacka Rijeka was 174-175 m3 s-1 (the incidence of 100 years) and there is a possibility for large flood waves to appear in the studied basin. Real soil losses, Gyear, were calculated on 2614-2921 m3 year-1, specific 229-256 m3 km-2 year-1 (1977-2017). The value of Z coefficient range from 0.444 to 0.478 and indicates that the river basin belongs to III destruction category. The strength of the erosion process is medium, and according to the erosion type, it is surface erosion. According to our analysis the land use changes in the last 40 years influenced the increase of the soil erosion intensity for 11% in the study watershed. Further studies should be focused on the detailed analysis of the land use changes trends with the other river basins at the national level, closely following responses of soil erosion to the changed land use structure. The results and approach also should be used by policymakers in all national natural resources organizations to highlight the role of management.

Quality and Quantity of Biological Production in Water Bodies with Different Concentration of Phosphorus: Case Study of Eurasian Perch.

For the first time, the quantity of protectors of cardiovascular deceases-omega-3 polyunsaturated fatty acids, eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA), obtained through fish (Eurasian perch) catch in water bodies of different trophic status was determined. A formula was drawn to calculate the quantity of obtained EPA + DHA (kg km-2 year-1) depending on the concentration of total phosphorus in water. It is found that the maximum quantity of EPA + DHA can be obtained by humans from fish caught in mesotrophic water bodies.

Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation?

Seaweed aquaculture, the fastest-growing component of global food production, offers a slate of opportunities to mitigate and adapt to climate change. Seaweed farms release carbon that maybe buried in sediments or exported to the deep sea, therefore acting as a CO2 sink. The crop can also be used, in total or in part, for biofuel production, with a potential CO2 mitigation capacity, in terms of avoided emissions from fossil fuels, of about 1500 tons CO2 km-2 year-1. Seaweed aquaculture can also help reduce the emissions from agriculture, by improving soil quality substituting synthetic fertilizer and, when included in cattle fed, lowering methane emissions from cattle. Seaweed aquaculture contributes to climate change adaptation by damping wave energy and protecting shorelines, and by elevating pH and supplying oxygen to the waters, thereby locally reducing the effects of ocean acidification and de-oxygenation. The scope to expand seaweed aquaculture is, however, limited by the availability of suitable areas and competition for suitable areas with other uses, engineering systems capable of coping with rough conditions offshore and an increasing market demand for seaweed products, among other factors. Despite these limitations, seaweed farming practices can be optimized to maximize climate benefits, which may, if economically compensated, improve the income of seaweed farmers.

Complexities and Uncertainties in Transitioning Small-Scale Coral Reef Fisheries

Coral reef fisheries support the development of local and national economies and are the basis of important cultural practices and worldviews. Transitioning economies, human development and environmental stress can harm this livelihood. Here we focus on a transitioning social-ecological system as case study (Moorea, French Polynesia). We review fishing practices and three decades of effort and landing estimates with the broader goal of informing management. Fishery activities in Moorea are quite challenging to quantify because of the diversity of gears used, the lack of centralized access points or markets, the high participation rates of the population in the fishery, and the overlapping cultural and economic motivations to catch fish. Compounding this challenging diversity, we lack a basic understanding of the complex interplay between the cultural, subsistence, and commercial use of Moorea's reefs. In Moorea, we found an order of magnitude gap between estimates of fishery yield produced by catch monitoring methods (~2 t km-2 year-1) and estimates produced using consumption or participatory socioeconomic consumer surveys (~24 t km-2 year-1). Several lines of evidence suggest reef resources may be overexploited and stakeholders have a diversity of opinions as to whether trends in the stocks are a cause for concern. The reefs, however, remain ecologically resilient. The relative health of the reef is striking given the socio-economic context. Moorea has a relatively high population density, a modern economic system linked into global flows of trade and travel, and the fishery has little remaining traditional or customary management. Other islands in the Pacific that continue to develop economically may have small-scale fisheries that increasingly resemble Moorea. Therefore, understanding Moorea's reef fisheries may provide insight into their future.

Jamuna River Erosional Hazards, Accretion &amp; Annual Water Discharge – A Remote Sensing &amp; Gis Approach

Abstract. This paper presents the results of some of the Jamuna River erosional hazards from Bahadurabad Ghat to Bhuapur (near Jamuna Bridge). Results are also presented on the Jamuna River accretion and water discharge. Landsat images from 1977 to 2014 and water discharge data were analysed to find out a relationship between dynamics of erosion and accretion for different time intervals with average annual water discharge. It is clearly established that total amount of erosion and accretion rates varies with different times. The highest erosion rate 21.15 km2 year-1 was observed in the period of 1989-1992 and the highest accretion rate 13.57 km2 year-1 was observed in the period of 1980-1989. The erosion and accretion values fluctuated with increasing average annual maximum water discharge but the difference between erosion and accretion had remained low before water discharge reached to 67000 m3s-1 and it is estimated higher after crossing annual average maximum water discharge of 67000 m3s-1. This discharge value also plays an important role on bar development and active channel. It is also observed that unvegetated bar areas remained higher than active channel areas before average annual maximum water discharge reached to 67000 m3s-1. Finally, all the erosional hazards and accretion values are compared and evaluated to see their influence on the annual discharge.