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This overview compares algal blooms and pelagic fisheries of the Arabian Gulf with the Sea of Oman. The data consist of remotely sensed characteristics, directly sampled and modeled. Elucidated seasonal trends were based on 15-year seasonal means, as well as weekly time series of physical parameters. The environmental characteristics (namely photosynthetically available radiation, atmospheric pressure, temperature, wind, aerosol optical thickness, surface currents, surface temperature, salinity, concentration of dissolved oxygen, nitrates, phosphates, chlorophyll-a, net primary production, phytoplankton, zooplankton biomass, fish larvae abundance, small and large pelagic fish catches) were compared between regions. In Sea of Oman, high concentrations of chlorophyll-a were associated with relatively high concentrations of nitrates and phosphates, as well as kinetic energy of surface currents which exceeded that in Arabian Gulf. The dinoflagellate Noctiluca scintillans is one dominat alga in the Sea of Oman, whereas diatom species are more common in the Arabian Gulf blooms. In general, the phytoplankton and zooplankton species diversity during winter was higher than in summer periods. Catches of small pelagic fish (in particular sardines) in the Sea of Oman exceeded that in the Arabian Gulf. This might be associated, in part, with differences in trophic levels interactions. The turnover rate of the net primary production through zooplankton in Sea of Oman was found to be much higher than in Arabian Gulf waters.
Seasonal dynamics of microzooplankton and changes in environmental condition were analysed during a one-year field sampling campaign in the Sea of Oman at two different stations. Monsoon winds in this region cause distinct seasonality patterns with high primary productivity during the south-west monsoon in summer (June to October) and north-east monsoon periods in winter (November to March). Microzooplankton in the Sea of Oman showed several biomass peaks throughout the year. In general, higher biomass occurred during the south-west monsoon when compared to the north-east monsoon period with maxima of 190 µg C l–1at the inshore station Bandar Al-Khyran at 1m and 308 µg C l–1at 10m water depth. At the offshore-station, peaks of 372 µg C l–1(1m) and 256 µg C l–1(20m) occurred during the south-west monsoon. A strong coupling between phytoplankton and microzooplankton was observed during monsoon periods but some microzooplankton peaked during inter-monsoon periods when chlorophyll concentration was low (Bandar Al-Khyran: 372 µg C l–1at 1m and 196 µg C l–1, 10m; Offshore-station: 419 µg C l–1, 20 m). The initiation of phytoplankton blooms in the Sea of Oman was bottom-up controlled due to strong seasonal nutrient influx during south-west and north-east monsoon periods. Highest microzooplankton biomass occurred during monsoon periods with a dominance of Noctiluciphyceae and peaks of 7596 µg C l–1at Bandar Al-Khyran (1m) and 5942 µg C l–1(10m). Copepod nauplii, Amoebozoa and Larvacea contributed substantially to microzooplankton biomass throughout the year. Ciliophora contributed low proportion to the total microzooplankton biomass peaking both during monsoon and inter-monsoon periods. During the spring inter-monsoon, choreotrich ciliates (tintinnids) showed distinct peaks of 15.9 µg C l–1at Bandar Al-Khyran (1m) and 17.7 µg C l–1(10m) as well as 18.2 µg C l–1at Offshore-station (20m). The interplay between bottom-up controlled primary production and top-down control mechanisms regulates the phenology patterns of specific microzooplankton groups in the Sea of Oman thus pointing at complex trophodynamic interactions at the lowermost foodweb level in this low-latitude ecosystem.
Boubyan Island is essentially undeveloped and the largest island in the northwest of the Arabian Gulf. Small otter trawls were used to sample 12 stations circling Boubyan Island each month, except November, from February 2004 through February 2005. All trawl catches, with the exception of large Skates and Rays, were returned to the laboratory for identification and processing. The total number of individuals captured by all 431 five-minute trawl tows was 81659. Species caught included 31 Crustaceans, 7 Mollusks, 5 Echinoderms, 1 Tunicate, 90 fishes, and 1 Sea Snake. The monthly total occurred species ranged from 27 to 78 and was high in the summer months (June to August) and low in the winter (December to February). Species richness and Shannon's diversity showed a similar seasonal change pattern with a range of 3.41–7.93 and 0.80–2.58, respectively. The seasonal changes of the number of species, abundance, species richness and diversity were probably caused by the migration and reproductive circle of the organisms. However, the variations for all these indices among different stations were relatively small and suggested a similar environmental conditions for the areas around Boubyan Island.
Canada and USA have over a 100-year history of international cooperation on Great Lakes management. For over 30 years, federal, state, and provincial governments have successfully used locally-defined ecosystem approaches to develop and implement remedial action plans to restore beneficial uses impairments in 43 Great Lakes Areas of Concern. Each remedial action plan identifies use impairments/causes, remedial/preventive actions to restore uses, and implementation responsibilities and timeframes. Areas of concern are removed from the list when all uses are restored. Long-term efforts are needed to ensure sustainability through adaptive management. Shared resources, like the Arabian Gulf and Great Lakes, require collaboration among boundary countries to achieve common goals. A network of regional technical and governmental representatives could be established under or affiliated with the Regional Organization of Protecting Marine Environment to promote cleanup and ecosystem-based management of degraded areas of the Sea. It would have to be flexible, not prescriptive, science-based, action-oriented, and result in well recognized benefits to all partner countries. Workshops or conferences could be convened to address ecosystem issues. This network must be value-added and build capacity, and could eventually lead to use of locally-defined ecosystem approaches to develop cleanup plans for degraded areas of the Gulf, similar to Great Lakes Areas of Concern. Gulf countries, through the Regional Organization of Protecting Marine Environment and with support of a network, could then come together every three-five years to report on progress, identify research needs, celebrate successes, and establish next steps. Gulf I, II, and III conferences are building blocks for such a network. A logical next step would be to engage the Regional Organization of Protecting Marine Environment in the establishment of a network for ecosystem-based management and co-sponsorship of a Gulf IV Conference or other forum. In the spirit of cooperative learning, further exchanges of both scientific research and management practices would be beneficial between the Great Lakes and the Gulf.
Leizhou Peninsula is located in the Indo-Burma biodiversity hotspot. However, information about freshwater fish species in this peninsula is very scarce. Based on surveys and a literature review, a total of 100 freshwater fish species (92 native and eight non-native) within seven orders, 21 families and 70 genera, have been recorded in the Leizhou Peninsula. Four species, Mud Carp (Cirrhinus molitorella), common carp (Cyprinus carpio), South Sharpbelly (Pseudohemiculter dispar), and Helmet Catfish (Cranoglanis bouderius) are listed as threatened species in red list of IUCN. Sand mining, aquaculture pollution, non-native aquatic species, and overfishing are the greatest threats to freshwater fish biodiversity of Leizhou Peninsula. For better sustainable development, conservation efforts should be focused on the establishment of protected areas, improvement of sustainable fishery management and control of nonnative species. This study provides management recommendations that will be useful for freshwater fish biodiversity conservation and fishery management in Leizhou Peninsula.
Conductivity elevation produces osmotic stress to aquatic biota and then alters biological communities. The responses of stream fish to conductivity remain unclear and strategies for protection are poorly developed. We collected data of fish and conductivity from sixty-two sites of the Taizi River to evaluate the changes to the fish community and species along the gradient of conductivity. Our results found that conductivity elevation was related to the regional development of urban and farmland and the local degradation of habitat quality. The community metrics of abundance and F-IBI, but not species richness and diversity, showed a significant linear correlation with conductivity. Conductivity of the top three F-IBI grades (excellent, good and normal) was significantly lower than those of the other two F-IBI grades (poor and bad). The boundary conductivity between normal grade and poor grade was approximately equal to 500 µS cm–1. We found different probability patterns for different species along the conductivity gradient; one capture probability pattern showed decline trend along the conductivity gradient. Except for two dominating and widespread species and one tolerant species, the remaining fish species of the first pattern should be designated as protection objects. In order to protect fish community integrity and sensitive species, sustainable land use management on the catchment scale and habitat quality improvement on the local scale should be given more attention by catchment managers.
When dealing with invasive fishes, permanent barriers may inhibit spread, but may not be feasible due to costs and logistical constraints. Alternatively, non-permanent barriers using electricity, light, sound, pressure, bubbles, and CO2 are being developed and deployed in efforts to limit and prevent the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable and testing is often lacking for both invasive and native species. We conducted a laboratory experiment to investigate the impact of vertical electric barrier on behaviour of Rainbow Trout, Oncorhynchus mykiss. In response to electric current, Rainbow Trout responded by significantly decreasing passage through the electric barrier zone and spending more time away from the electric barrier when it was turned on during the stimulus period compared to pre-stimulus period. Moreover, when interacting with electric barrier, Rainbow Trout exhibited certain behaviours (e.g. stunned and remained on the same side of the barrier, stunned and crossed the barrier) more than others (e.g. approach and retreat, deflected, and paralyzed). Moreover, it appears that Rainbow Trout remained distant from the electric barrier even after the electric barrier was turned off. Our results indicate that relatively weak electric gradient (i.e. voltage gradient: 0.2 – 0.4 v·cm–1, power density: 3 – 42 µW·cm–3) can inhibit the movement of Rainbow Trout. Our results also highlight the importance of detailed investigation of behavioural responses of target species when evaluating and considering fish-deterrent or guidance technologies.
Analysis of beach profile data over the period 1992–2014 at 14 beaches on mainland Anguilla and the offshore cays of Prickly Pear and Sandy Island, showed an overall erosion trend with a mean erosion rate of –0.51 m yr–1. Eleven beaches showed erosion, while three beaches showed slight accretion. Over the period of measurement nine hurricanes passed close enough to Anguilla to significantly impact the beaches. Analysis of a ten year (2008–2017) record of marine monitoring of fish, marine plants, corals, algae and other invertebrates at 15 sites around Anguilla has shown an 11% drop in coral cover and a 10% increase in algae cover. This contributed to a post Hurricane Luis marine monitoring survey in 1996, which illustrated the dramatic mortality of Anguilla's reef ecosystem that began in the late 1970s with the emergence of white-band disease and continues to this day. An analysis of the changes at each beach shows multiple causal factors including geomorphological adjustments, high swell wave events and hurricanes, hard and soft coastal protection measures, sea level rise and the decline in overall reef heath. Relative importance of each of these factors varied from beach to beach and contributed to the variations in the amount and direction of change at the different locations. The analysis highlights the need to focus on beach and coral reef conservation measures and legislative changes in order for tourism and the economy of Anguilla to thrive.
Coastal wetlands in Qinhuangdao play a vital role in the regional ecological environment. The value of the ecosystem services of the coastal wetland was evaluated in terms of provision services, regulation services, culture services and supporting services by particular methods. Results indicated that coastal wetland area in Qinhuangdao was about 39,918.00 hm2 and annual value of ecosystem services in 2015 was around 174.32 × 108 yuan (yuan: Chinese Currency, 6.5 yuan = 1 USD as of 2015) (about $2.68 billion). The value of provision services, regulation services, culture services and supporting services accounted for 12.3%, 3.3%, 55.0% and 29.4% of the total value, respectively. Recreation value of culture services had the highest proportion (54.4%), which indicated that recreation service was the crucial role of the coastal wetland in Qinhuangdao. Coastal wetland ecosystem of Qinhuangdao provides tremendous value through ecological products and purposes every year and conservation should be enhanced. Meanwhile, cultural connotation construction, such as the creation of a locally characteristic culture, should be specially enhanced to fully unearth its recreation value.
Based on the geometry and surface in Daya Bay, we artificially divided the reclamation projects into three periods to analyze the influences and changes on hydrodynamic conditions as a result of the reclamation projects. Three periods of tidal current fields, tidal prisms, and water exchange capacity are simulated by the Finite-Volume, primitive equation Community Ocean Model and the characteristics and trends of hydrodynamics in Daya Bay are discussed. The combination of observation and simulation in this paper gives a good description on the tidal dynamic system in Daya Bay. As indicated by model results, the tidal current velocity in the Bay totally decreases after numerous activities associated with reclamation construction. The decreasing current velocity region is mainly distributed near the Xiachong and Gangkou chain islands. The current velocity in 2015 decreases by approximately 5cm s–1 compared with velocities before 2000. Future reclamation activities will exacerbate these decreasing current velocity trends in some regions. Compared with 2015, the tidal prism has significantly decreased by 1.3622× 107 m3 due to planned reclamation. The half-water exchange times for Daya Bay in 2015 and after planned reclamation are 178.9 and 177.4 days, respectively. The water exchange capacity in Fanhe Harbor is weaker than other water fields throughout Daya Bay.