Estuaries: Dynamics, Biodiversity, and Impacts

The biodiversity of inland is alarmingly declining primarily due to unsuitable and unethical fishing practices prevalent in the rivers and streams. A variety of destructive type of fishing activities are being practised in the inland water bodies of Kerala such as poisoning using chemicals, insecticides and seeds of plant origin, dynamiting, electric fishing etc. This creates various new and intense pressures leading to decline in species number. The Poonthura backwater in the south west coast of India (Kerala state) is a typical estuary. It is located at a latitude between 8° 25’ and 8°3’N and longitude 76° 55’ and 77°00’E. This estuary is circular in shape enclosing an island called Edayar. This is separated from the Lakshadweep Sea by a sand bar at Poonthura which opens during the monsoon period consequent to heavy discharge of water from the adjacent rivers. In the present study the biodiversity survey of fish and shellfishes of this backwater was carried on for one year (April 2013 to March 2014). The data on fish community collected during the surveys were correlated with the physico-chemical parameters, nutrients of the water samples, carbon, nitrogen and phosphorous and heavy metals such as copper, lead, manganese, nickel and zinc of the sediments. A total of 32 species were reported during the whole year. All the fish and shellfishes showed seasonal influence with more fresh water species in monsoon months. The marine fishes occur more during pre monsoon. The pre monsoon reported less percentage and non availability of most of the fish species in catches. The analysis of the condition of fishes is of considerable significance in determining the cycle of changes related to other biological aspects of fishes such as feeding and breeding. By virtue of their position at the interface of sea, river and land, estuaries support a distinctive assemblage of birds, fishes, invertebrates as well as characteristic floral communities such as mangrove swamps and salt marshes. The physico-chemical properties in relation to catchment status with condition of the estuary were determined. The correlation analysis proved that, there is a relationship between environmental parameters and survival of the species in those ecosystems.

Benthic habitats can be broadly classified as either vegetated or unvegetated. Seagrasses are the dominant form of submerged vegetation. Vegetated bay bottoms are generally more productive than unvegetated bottoms. Over 85% of seagrasses in Texas occur in estuaries of the Corpus Christi Bay National Estuary Program (CCBNEP) study area. Seagrass ecosystems are noted for high commercial and sport fishery landings. This correlation is often attributed to the high primary and secondary productivity associated with large seagrass beds in the CCBNEP study area. Disturbances, operating at many different scales, however, can profoundly affect benthic processes in estuaries and threaten fishery resources. For example, upper Laguna Madre appears to be undergoing a dynamic transition from a seagrass-dominated to a phytoplankton-dominated system as a result of a brown tide algal bloom. This large scale disturbance has resulted in pronounced changes in the trophic dynamics and relative importance among key plant and animal species within the system. What is not known is if the disturbance in Upper Laguna Madre is natural or influenced by man's activities, or if there are interactive effects due to natural fluctuations in the environment and anthropogenic input. Therefore, there is a need to identify natural and anthropogenic disturbances and characterize effects on benthic habitats. The four most important benthic habitats in the CCBNEP study area are: seagrass beds, oyster reefs, open bay muddy bottoms and shoreline sandy bottoms. Disturbances to benthic habitats are well known. Seagrasses are stressed by nutrient enrichment, propeller scarring, and especially light reduction caused by brown tide, turbidity, and dredging. Oyster reefs are stressed by reduced freshwater inflows and concomitant higher salinities. Bay bottom habitats are a victim of their own bounty. The large economic benefit the CCBNEP region derives from shrimping and sport fishing, which is supported by bay bottom habitats, is at risk due to mechanized harvest. Trawling continually turns over sediment, keeping the benthos in a continual state of low abundance and biodiversity. Bycatch-removes potential food for recreationally and commercially important fish species. Numerous disturbances resulting from human activities and natural events that affect physical, chemical, and biological characteristics of estuarine benthic habitats have been identified within the CCBNEP study area. Examples of human activities include: shrimp harvesting with bottom trawls, commercial tug and barge operations, recreational boating, dredging, altered currents, altered inflow, nutrient and contaminant input, and hydrocarbon exploration and production. Each activity has variable effects on the different types of bay bottom habitats. Examples of natural disturbances include: wind-generated resuspension and deposition of fine sediments, abrupt salinity changes due to direct rainfall and runoff, erosion due to storms, fish mortality due to freezes, long-term climatic changes, and harmful algal blooms.

doi: 10.12957/geouerj.2016.20426 A construcao de barragens e a regularizacao da vazao tem implicacao direta no sistema hidrologico do Baixo Sao Francisco (BSF), com reflexos nos processos de erosao e sedimentacao e na relacao homem-natureza. O objetivo do presente artigo e discutir e compreender a organizacao dos agroecossistemas do estuario do rio Sao Francisco a partir do estudo de seus componentes e suas interacoes, estrutura, funcionalidade, inputs e outputs do sistema, alem de seus limites territoriais. A avaliacao das propriedades dos agroecossistemas, como proposto por Conway (1983 e 1987) e Marten (1988), constitui uma importante ferramenta para a compreensao da interacao dos elementos do sistema ambiental do estuario, bem como a identificacao e discussao dos impactos na estrutura, funcionalidade e avaliacao das propriedades (produtividade, estabilidade e equidade) dos agroecossistemas. A regularizacao da vazao provocou mudancas na dinâmica ambiental, reduzindo a agrobiodiversidade, comprometendo a sustentabilidade dos agroecossistemas e a oferta de alimentos para a fauna aquatica, interferindo no processo de renovacao das varzeas e na explotacao dos recursos pesqueiros.

Krabi River Estuary, a ramsar site located in southern Thailand, is dominated by two major natural vegetation assemblages, i.e. mangrove forests and seagrass beds. According to the cluster development strategy, the cabinet has approved in principle to develop Krabi as the global marine tourism center and economic gateway of Asia. This study aimed to assess the economic value of the site, using market price and benefit transfer. The impact on economic activities with the 5% annual decline of mangrove forests was evaluated. The estimated annual use value of the site was $9.7 million for recreation and tourism. The economic value of mangrove forests was $758/ha. The net present value of mangrove forests was $73.1 million based on 7% discount rate and 15-year time line. An approximate impact of mangrove change follows the study of Ruitenbeek (1992). It was assumed that the impact on local direct resource extraction and loss in biodiversity would occur at the year after the depletion of the forest. The impact on the productivity of local fishery would occur in the fifth year and on tourism in the tenth year. Thus, value loss of mangrove at the annual rate of 5% in the net present term became $21.0 million or $2.3 million per year. The results imply that a development project that causes the same rate of mangrove destruction must generate a least an income of $2.3 million per year to be considered as an economically feasible project.

In Brazil, industrial fishing of the piramutaba catfish is performed at the estuary of the Amazon River, utilizing bottom-trawl nets as equipment. This fishing technique is considered potentially the most harmful to the environment and to biodiversity, due to the destruction of biomes and incidental capture of several species, called “bycatch.” In order to characterize the species which compose the ichthyofauna bycatch of the piramutaba catfish, we analyzed 459 fishing trawlers between the years of 2002 and 2008, in the allowed and forbidden areas. The results revealed that the ichthyofauna bycatch of the piramutaba consists of 38 species, divided in 33 genera and 17 families. The piramutaba was confirmed as the main species, consisting of 76% of the overall product, and the gilded catfish as the main bycatch species, consisting of 7.05% of the product. We have recorded the incidence of jewfish (Epinephelus itajara), which can be found in the International Union for Conservation of Nature list of critically endangered species. In despite the production was higher in the rain season than in the dry season, there was no statistical difference in the rate of biodiversity in different areas or periods.

This article highlights some salient ecological features of Indian coastal resources and the need for a viable coastal resources management plan. The transition between the land and the sea is one of the most fragile, complex and a productive ecosystem. It is bestowed with enormous resources, both - living, non-living and is a potential area for recreation and harnessing non-conventional energy resources (wave and wind energy). This is the zone of dynamic activity, constantly transforming itself to maintain equilibrium, under the varying intensity of the natural processes operating here Coastal zone of India has diverse ecosystems like mangroves, corals, beaches, wetlands, estuaries, lagoons and backwaters harboring many ecologically and economically important fauna and flora and also serves as a barrier against many destructive natural hazards. Coastal zone is a region of diverse activity, both complementary and conflicting to each other. Accelerated and unscientific developmental activities have induced catastrophic consequences. In order to optimally utilize&reap the benefits, without hampering the fragile balance, it is necessary to adopt coastal management strategies based on solid scientific foundation that allow for multiple use of the resources without causing serious damage to the environment. Indian seas are witnessing increased anthropogenic activities like marine fishing, off-shore oil and gas, marine transport, dumping ground for waste disposals, etc all of which have been bringing about changes in the coastal environment. Increasing stress due to development of industries, trade and commerce, tourism and resultant human population growth and migration towards coastal cities and urban centers pose a serious threat to the to the health of these coastal ecosystems and to lives and livelihoods of coastal communities. The industrial development of coast has resulted in degradation of coastal ecosystems and diminishing the living resources of Exclusive Economic Zone (EEZ) in the form of coastal and marine biodiversity and productivity. Municipal sewage, land use, tourism, maritime transport, offshore oil exploration and production, dumping at sea degrade the marine environment. Felling of mangroves and clearing of forests increase the sedimentation rate affecting the live coral and species diversity. Mangroves are a crucial component deserving high priority in any coastal zone management plan as they are degraded and destroyed due to conversion into agriculture, aquaculture and industrial land. Fishery and fishery resources are another major component in coastal resource management. Preliminary efforts to develop a model coastal zone plan in three different stretches refined our skills to expand the plan at country level. As a result, an exhaustive management plan is being implemented at three different coastal states of the country. It is strongly hoped that many maladies afflicting coastal environment could be effectively addressed by formulating and actively adopting an all encompassing and exhaustive coastal zone management plan. Options to tide over this persistent issue is being debated at national and even international levels and some suggestions consistently made by public interest groups and NGOs includes: Earmarking exclusive zone for fishery, mangroves and other coastal biodiversity and for settlement for fishing communities. All fishery development recommendations suggest that Integrating fishing community with the ongoing development could be initiated to reverse their poverty. It could be done only through long term planning to enhance their special skills which will make them employable and eventually integrate them with the ongoing developmental process. It is also to be remembered that downslide in economic returns of fishing sector is a global phenomenon and Indian fishermen are no exception to this. It is strongly hoped that many maladies afflicting coastal environment could be effectively addressed by formulating and actively adopting an all encompassing and exhaustive coastal resource management plan.

This is the first report about the biodiversity and ecology of chytrids in Taiwan. Periodically survey of chytrids in Tsengwen Reservoir, Tsengwen River, Gaoping Weir and Mudan Reservoir were proceeding. Five genera and thirteen species of chytrids are isolated and identified. Rhizophydium is the most frequent genus. The dominant species isolated from individual collecting area are: Rhizophydium sphaerocarpum var. sphaerocarpum in Tsengwen Reservoir, Cladochytrium replicatum in estuary of Tsengwen River, Rhizophydium laterale and Phlyctochytrium chaetiferum in Gaoping Weir, and Rhizophydium laterale in Mudan Reservoir. At the same time, chytrids are isolated from four collecting areas only at July. The percentage of similarity among four areas is very low.

Sonneratia apetala,a native mangrove species in India,Bengal and Sri Lanka,was introduced in 1985 to Dongzhaigang Mangrove Nature Reserve in Hainan Island from Sundarban,southwest of Bangladesh.The trees beared fruits 3 years later.Then it was further introduced from Dongzhaigang to Lianjiang of Leizhou Peninsula,Shenzhen Bay,Chenghai of eastern Guangdong Province and Jiulongjiang Estuary of Fujian Province and grew well.Since 1998,S.apetala has been extensively used in mangrove restoration in China.With its rapid growth and quick expansion of planting area,some disputes on S.apetala introduction have emerged in recent years,such as whether it competes with indigenous species for resource and habitat,whether it will become an invasive species,and whether it should be restricted or widely used in mangrove planting programs.In order to explore these questions,studies of S.apetala introduction since late 1980s were reviewed within four aspects,namely:(1) environmental adaptability,changes of physiological characteristics and genetic diversity among communities of different introduction locations;(2) silviculture techniques,including planting,seedling and sapling nursing techniques,post-planting management;(3) stand productivity,including biomass accumulation,litterfall production and nutrient elements absorption;and(4) ecological effects,including protective effect,environmental purification,ecological control,impacts on indigenous mangrove species,and possibility of biological invasion.We concluded that(1) S.apetala grows well in intertidal zones of thick and soft muddy soil with low salinity(0—15‰) in China′s south coasts,and can be used as pioneer species in mangrove afforestation due to its fast-growth,high adaptability and stress resistance,but will threaten the growth of indigenous mangrove species if it is introduced to native mangrove communities or planted densely with indigenous species;(2) there are obvious effects of ecological protection,environmental purification and control over Spartina alterniflora for S.apetala forest;(3) the natural spread speed of S.apetala is slow due to the restraint of salinity,light intensity,temperature,soil and tide,and no significant impacts on the structure,functions or biodiversity of native mangrove cummunities are found,so whether S.apetala will be an invasive species cannot be determined at present;(4) with the enhancement of environmental adaptability of S.apetala,its ecological effects might change,and one should be cautious with further expansion of the plantation before its adverse ecological impacts are clear.We suggest that it should be planted mainly on low tidal beaches where native mangrove species cannot grow.Finally,we put forward some important fields for future research,including(1) monitoring of ecological influences of S.apetala on indigenous mangrove communities and the trend of biological invasion;(2) impacts of S.apetala on coastal aquatic animals;(3) planting patterns of mixed forest of S.apetala and indigenous mangrove species,considering species diversity,self-sustainability,comprehensive ecological effects and landscape,and then further research into impacts of S.apetala on indigenous mangrove species under these patterns;and(4) economic utilization of S.apetala.

The coastal zone of Indonesia, especially in the eastern archipelago, is composed of typical tropical small island ecosystems such as estuaries, coral reefs, seagrass meadows, algal beds, and sandy beaches which are habitats of many groups of marine organisms including Echinoderms. The biodiversity of many small islands in this area was understudied, including Bakalan Island of Banggai Islands in Central Sulawesi. The purpose of this study was to determine the diversity of Echinoderms (Echinoidea and Holothuroidea) in Bakalan Island. This study applied the purposive sampling technique with the 2 x 2 m quadrats were placed along a 100-meter transect with ten-meter intervals. There are nine species of echinoderms found in this study including Salmacis sphaeroides, Mespilia globulus, Tripneustes gratilla, Echinometra mathaei, Diadema setosum, D. savigny, Echinothrix calamaris, Holothuria atra , and Synapta maculata . The first seven species belonging to the class Echinoidea while the latter two belong to the class Holothuroidea.

La biodiversidad marina en la Guyana Francesa esta fuertemente influenciada por los aportes amazonicos, los cuales constituyen un factor estructurante de los ecosistemas estuarianos, costeros y de plataforma continental. Ademas, debido a las cambiantes condiciones meteorologicas y oceanograficas, la variabilidad estacional e inter-anual puede jugar un rol importante en la estabilidad o la modificacion de los parametros medio-ambientales que afectarian la biodiversidad ecologica, poblacional y genetica de los ecosistemas locales. Los estudios llevados a cabo sobre la biologia de las especies marinas y litorales se refieren principalmente a especies de interes comercial, especies protegidas en peligro de extincion, y sobre todo a las caracteristicas del funcionamiento de ciertos ecosistemas costeros y litorales caracteristicos como los estuarios, bancos de fango, playas de arena, y sobre todo los manglares. La idea de estudios o series de estudios mejor coordinados entre si a nivel regional e internacional, emerge como una necesidad para una mejor estimacion y comprension de la biodiversidad marina. Estos estudios beneficiarian de una importante cooperacion internacional que pemitiese comparar e integrar el conjunto de datos obtenidos en el pasado, llevar a cabo misiones oceanograficas conjuntas, mutualizar y homogeneizar los protocolos analiticos, y favorecer el intercambio de tecnicas y estrategias por intermedio de intercambios de cientificos y estudiantes en formacion de postgrado. Finalmente, estudios comparativos sobre la biodiversidad de sistemas costeros analogos sudamericanos permitirian de alcanzar una mejor estimacion de la biodiversidad marina de este continente.

Mangrove forest is an important vegatation type on biodiversity conservation and wetland ecological protection.Acquisition changes on mangrove area timely is an urgent need for protection.In this paper,taking Fujian Zhangjiang Estuary National Nature Reserve as study area,multi-temporal ALOS PALSAR data acquired in 2007 are processed.The temporal change characteristics and depolarization characteristics on L band HH、HV channel are analyzed.On L band HH、HV channel,backscatter information does not change significantly over time,which is similar to local forests,but depolarization ability between mangrove forests and local forests is obviously different.Compared to temporal information,polarization information is more important for mangrove forests extraction.Based on object-oriented approach classification,we proposed a method for mangrove forests extraction by using HV,HH polarization and their ratio from a mono temporal data.The results show that mangrove can be extracted with high accuracy.

Estuaries or also known as ustuaria is the area of water bodies into a meeting between one or more rivers in coastal areas with marine areas. Juata Laut waters located in the northern part of Tarakan Island. These waters are a small part of the estuarine waters in this region, which connects the river Sesayap which is one of the major rivers located in the northern coastal region of North Kalimantan with the surrounding sea area. The purpose of this study was to determine the type and level comparison fishes diversity found in mangrove waters and traditional farms around the waters of Juata Laut Tarakan City North Kalimantan province. Types of fish found in the waters of the Sea of mangrove Juata as many as 23 types, while in pond waters around 19 species. Level of biodiversity of fish in mangrove waters and traditional farms around the waters of the Sea Juata classified in the spring rate which means it has a lower level of community stability. Keywords : Comparation, diversity, fishes.

The Institute consists of researchers with expertise in: catchment and river processes; water allocation and environmental flows; coastal and estuarine processes; aquatic biodiversity and conservation; restoration science; and monitoring and assessment. The collection includes metadata related to research undertaken as part of the Tropical Rivers and Coastal Knowledge (TRaCK) hub. The collection also includes grey literature and metadata on various data from ARI researchers. The collection can be searched from public access and any requests for copies of material can be made to the authors or to the ARI custodian.

The Araçá Lagoon (Recife) and Manguezal Chico Science (Olinda) are two estuarine-lagoons environments in Pernambuco State, that receive
\norganic and inorganic wastes from urban origin. From the hypothesis that they show a low biological diversity this work aimed at making an inventory
\nof the vegetation and epibenthic fauna from the intertidal zone, to assess how environmental changes affected the biological community composition.
\nFour samplings were done in each lagoon in 2005, seeking to relate the species with its ecological preferences about substrate and tide height. Both
\nlagoons showed a defi cient hydrodynamism on account of the nature and formatting of the artifi cial canals that conduct the tides, the considerable
\naffl uence of domestic sewers waters and the low indices of dissolved oxygen. The fauna of these lagoons differed very little among itself, being constituted
\nby mollusks (Littoraria angulifera, Melampus coffeus, Neritina virginea, Mytilopsis leucophaeta) and crustacean species (Ucides cordatus,
\nAratus pisonii, Goniopsis cruentata, Sesarma rectum and Amphibalanus amphitrite). In the Chico Science mangrove forest, in addition to the
\nspecies Avicennia schaueriana, Rhizophora mangle and Laguncularia racemosa (predominant), there were also found Ligia exotica and Uca
\nthayeri. In the Araçá Lagoon, with a monospecifi c forest of L. racemosa these animal species were replaced by Uca burgesi and U. rapax. Considering
\nthat the sampled benthic macrofauna was comprised of species with a pantropical distribution, eurihaline and suffi ciently resistant to the environmental
\nand anthropic actions, it is suggested that the faunistic grouping common to both lagoons be a bioindicator of organic sewerage pollution, as long as
\nonly those species are found to in the estuarine environment.

Mangrove ecosystems are dense forests along the tidal estuaries and comprise incredible biological diversity. Mangrove trees are salt tolerant and survive in muddy anaerobic soils by the presence of pneumatophores (breathing roots). Mangroves have crucial ecological and economic importance. They carry out the source and sink in the carbon cycle, and protect the coasts from floods, tsunamis and other disasters. Mangrove leaves and bark are potential sources of pharmaceutical compounds to treat AIDS, jaundice and cancer. However, unregulated urban development, increased pollution, altered distribution and national highway expansion, bridges and increased tourism has resulted in the most destructive impact on mangrove forest. In the present study, a field survey of mangrove sites in Goa like the areas of Cortalim, Ribandar, Old Goa, etc. has conducted to observe the mangrove morphology, and growing pattern and analyse the impact of urbanization on declining mangrove health. Further, a survey was conducted to track public awareness about the declining mangrove ecosystem. The individuals were divided into four different categories and five questions were asked including whether they are aware of mangroves, their occurrence, their decline, and measures to protect them. Results suggest that most people are aware of declining mangroves but haven't experienced mangrove declines in their locality. Most people suggest that creating awareness, building mangrove farms and implementing strict rules can help in conserving mangroves.