Sustainability and Local People’s Participation in Coastal Aquaculture: Regional Differences and Historical Experiences in Sri Lanka and the Philippines

This article discusses environmental sustainability in aquaculture and its contribution to poverty alleviation, based on field studies in Sri Lanka and the Philippines. The aquaculture practices studied are the monoculture of the black tiger prawn (Penneaus monodon) and milkfish (Chanos chanos) and the polyculture of the two species together with the mud crab (Scylla serrata). Factors affecting economic viability, social equity and environmental impacts in aquaculture are discussed and used to illuminate local and regional differences between aquaculture in Sri Lanka and the Philippines. Findings indicate that the most significant difference is the level of participation by local people (i.e., people originating ≤10 km away from the farm location). In the Philippines, 84 % of the people involved in aquaculture are locals, whereas in Sri Lanka, 55% are outsiders. Whether differences between the two areas can be explained by analyzing regional conditions, which might have resulted in different aquaculture practices, is discussed. In Sri Lanka, semi-intensive shrimp monoculture is currently the most common practice, whereas in the Philippines, extensive shrimp/fish polyculture is more common. Previous studies, as well as fieldwork, indicate that extensive culture practices reduce environmental impacts and benefit local people more. Sustainability in aquaculture is, however, also dependent on the extent of mangrove conversion into ponds. As such, extensive and locally owned farms do not necessarily result in an all but sustainable situation. Keeping this in mind, it is discussed if extensive polyculture practices might result in a more sustainable aquaculture, both environmentally and socioeconomically.     

Seasonal variation in settlement and spiculation of sponge larvae

A settlement study, based in the Hauraki Gulf, Auckland, New Zealand, has revealed 3 different seasonal reproductive patterns among Demospongiae. Species which settled on our substrates can be divided into summer settlers, winter settlers, or all-year-round settlers. The composition of these groups is given, and the affinities and habitats of the constituent species are commented on. Variation in aspects of the spicule complement have been observed and discussed for three species: Mycale macilenta, Microciona coccinea and Ectyomyxilla kerguelensis.     

Free amino acid patterns and the classification of the Demospongiae

An investigation of the free amino acid patterns of 67 species representing 50 genera of West Indian Demospongiae has been undertaken to examine the value of this biochemical approach in adding another parameter to phylogenetic inquiries. Two-dimensional thin-layer electrophoresis and chromatography were used to separate mixtures of naturally occurring ninhydrin-positive compounds. Individual components were identified as far as possible, and the fingerprints or patterns of the species studied were used as a basis for evaluating relationships. The subclass Ceractinomorpha is a relatively homogeneous group, with free amino acid patterns characterized by a consistent representation of protein amino acids and by the absence of compounds other than taurine and hypotaurine in the neutral region of the chromatogram. Two variants of this general pattern can be recognized, one found in the orders Dictyoceratida and Poecilosclerida, the other occurring in the order Haplosclerida and the family Halichondriidae of the order Halichondrida. Unexpected results within this subclass are the wide separation of the dictyoceratid families Spongiidae and Verongiidae, the anomolous patterns of the genera Agelas and Iotrochota and of the family Callyspongiidae, and the suggestive affinities of the family Hymeniacidonidae with the order Hadromerida. The subclass Tetractinomorpha appears to represent a polyphyletic assemblage in which 5 recognizable patterns can be distinguished. These represent the orders Homosclerophorida, Choristida, Spirophorida, Hadromerida and Axinellida. Of interest are the suggestions that the order Choristida is in itself a heterogeneous group, and that certain genera now placed in the order Axinellida may in fact be more closely related to the Poecilosclerida.     

Results from the first year of the Swedish dioxin survey

PCDD/F levels are presented for food baskets, raw and fried herring, wolf muscle and moose tallow collected from the same area, three burbot liver samples, a sediment core from the Baltic Sea and leach water from three garbage dumps. Levels in food baskets were at or below detection limits making the estimation of intake via the diet difficult. Frying herring produces no net change in PCDD/F levels. Moose have lower PCDD/F levels than wolf from the same area. Levels in burbot liver samples are much higher near industrial discharges than in a more undisturbed area. The top 4 cm of the sediment core contain the highest levels of PCDD/F. Thereafter the levels drop and reach a low level. This low level is probably caused by contamination during sampling and is not evidence of PCDD/F presence far back in time. Leach water from city dumps contains low levels of PCDD/F but that from a dump that takes industrial wastes had higher levels and a different congener pattern.     

Challenges to measuring,monitoring, and addressing the cumulative impacts of artisanal and small-scale gold mining in Ecuador

Portovelo-Zaruma, Ecuador is an artisanal and small-scale gold mining (ASGM) region with approximately 6000 gold miners working with mercury and cyanide. Although artisanal gold mining (AGM) has taken place in Portovelo-Zaruma for centuries, highly mechanized small-scale gold mining (SGM) processing plants capable of increased throughput began being built in the 1990s. While there are benefits associated with ASGM, there are also negative impacts experienced by the miners and the surrounding communities. To take advantage of ASGM as a poverty-alleviating mechanism while reducing unwanted externalities, the cumulative impacts must be understood. Numerous challenges to measuring, monitoring, and addressing ASGM impacts result from the complexity of the impacts themselves, the nature of the gold mining as an informal industry, and the shortfalls in the current regulatory framework. These are discussed in the context of ongoing, unresolved issues including efforts to address trans-boundary water pollution, management of mining waste, and conflicts regarding priorities, ambiguities, and enforcement of existing regulations and policies. Internationally, interventions to address both AGM and SGM impacts have typically focused almost exclusively on technological changes through the elimination of mercury use. Our analysis suggests that to better address ASGM and their cumulative impacts in Ecuador, it will be beneficial to revisit the legal definitions of AGM and SGM. Additionally, promotion of information-based strategies including educational outreach programs and cross-scale and cross-level mitigation methods may also be beneficial. The success of these strategies to reduce ASGM-related cumulative impacts will depend on sufficient funding and the commitment of stakeholders.     

Levels and possible sources of PCDD/PCDF in sediment and pike samples from Swedish lakes and rivers. (Part one)

One goal of the Swedish survey project is to discover possible sources of PCDD/F. Bottom sediment and pike were sampled at various sites near different types of industries along the coast line of two lakes and one river. The results show background levels of PCDD/F in some lakes which can only be explained by atmospheric input. In some lakes paper mill emissions of chlorinated PCDD/F give high levels of local contamination (≈1 ng/g IG) within short distances (<1 km) from the source. PCDD/F from paper mill effluents are transported long distances and traces can be detected over the entire lake area. The PCDD/F levels in pike are correlated with levels in the underlying sediment.     

Using the soil and water assessment tool to estimate achievable water quality targets through implementation of beneficial management practices in an agricultural watershed

Runoff from crop production in agricultural watersheds can cause widespread soil loss and degradation of surface water quality. Beneficial management practices (BMPs) for soil conservation are often implemented as remedial measures because BMPs can reduce soil erosion and improve water quality. However, the efficacy of BMPs may be unknown because it can be affected by many factors, such as farming practices, land-use, soil type, topography, and climatic conditions. As such, it is difficult to estimate the impacts of BMPs on water quality through field experiments alone. In this research, the Soil and Water Assessment Tool was used to estimate achievable performance targets of water quality indicators (sediment and soluble P loadings) after implementation of combinations of selected BMPs in the Black Brook Watershed in northwestern New Brunswick, Canada. Four commonly used BMPs (flow diversion terraces [FDTs], fertilizer reductions, tillage methods, and crop rotations), were considered individually and in different combinations. At the watershed level, the best achievable sediment loading was 1.9 t ha(-1) yr(-1) (89% reduction compared with default scenario), with a BMP combination of crop rotation, FDT, and no-till. The best achievable soluble P loading was 0.5 kg ha(-1) yr(-1) (62% reduction), with a BMP combination of crop rotation and FDT and fertilizer reduction. Targets estimated through nonpoint source water quality modeling can be used to evaluate BMP implementation initiatives and provide milestones for the rehabilitation of streams and rivers in agricultural regions.     

Continuous water quality monitoring for the hard clam industry in Florida, USA

In 2000, Florida's fast-growing hard clam aquaculture industry became eligible for federal agricultural crop insurance through the US Department of Agriculture, but the responsibility for identifying the cause of mortality remained with the grower. Here we describe the continuous water quality monitoring system used to monitor hard clam aquaculture areas in Florida and show examples of the data collected with the system. Systems recording temperature, salinity, dissolved oxygen, water depth, turbidity and chlorophyll at 30 min intervals were installed at 10 aquaculture lease areas along Florida's Gulf and Atlantic coasts. Six of these systems sent data in real-time to a public website, and all 10 systems provided data for web-accessible archives. The systems documented environmental conditions that could negatively impact clam survival and productivity and identified biologically relevant water quality differences among clam aquaculture areas. Both the real-time and archived data were used widely by clam growers and nursery managers to make management decisions and in filing crop loss insurance claims. While the systems were labor and time intensive, we recommend adjustments that could reduce costs and staff time requirements.