T. Joydas - Academia.edu (original) (raw)
Papers by T. Joydas
MACROBENTHIC COMMUNITY STATUS 12 YEARS AFTER THE 1991 GULF OIL SPILL INCIDENT T.V. Joydas1*, Moha... more MACROBENTHIC COMMUNITY STATUS 12 YEARS AFTER THE 1991 GULF OIL SPILL INCIDENT T.V. Joydas1*, Mohammad A. Qurban1, Angel Borja2, P.K. Krishnakumar1, Abdulaziz Al-Suwailem3 1Center for Environment and Water, Research Institute, King Fahd University of Petroleum and Minerals, P. B. No. 1995, Dhahran–31261, Saudi Arabia, 2AZTI-Tecnalia; Marine Research Division; Herrera Kaia, Portualdea z/g, 20110 Pasaia, Spain, 3Marine Core Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. E-mail: tvjoydas@kfupm.edu.sa The Gulf war in 1991 resulted in the intentional discharge of an estimated 8–11 million barrels of crude oil into the Gulf and became the largest spill in history. The spill caused a drastic impact in the coastal areas located between Ras-Al-Khafji in the north and Abu Ali in the south of the Saudi Arabian coast. In Saudi Arabia, the greatest impact of the spill was visible in the nearshore region of the open water and in the sheltered inner bays. A consisten...
ICES Journal of Marine Science, 2015
Because of the increasing oil industry development in the Arabian Gulf, hundreds of oil and gas f... more Because of the increasing oil industry development in the Arabian Gulf, hundreds of oil and gas facilities have been installed in both offshore and inshore areas during the last few decades. However, no studies have been conducted till now on the influence of these platforms on the structure and composition of marine faunal assemblages. The present work addresses this issue to propose environmental management measures connected to the utilization of fishery resources. Offshore and inshore surveys were carried out along the Saudi Gulf waters using trawl and beach-seine nets, respectively. Data relative to only fish (offshore) and fish and invertebrates (inshore) were collected concurrently with several factors: density of oil and gas facilities (offshore), distance to the nearest coastal platform (inshore), oceanographic variables, and habitat characteristics. Results of offshore surveys indicated higher fish density-both total and of fishery resources-in locations with a higher number of oil and gas facilities within a 5 km radius, whereas biomass density was not significantly different. Hence, oil and gas facilities seem to serve as nursery areas for small fish. For inshore communities, more species and diversity were found in stations closer to coastal oil and gas facilities. In addition, among the five coastal embayments sampled, those with more oil and gas facilities had more species. The findings of the present work support the hypothesis of a positive net ecological role of oil and gas platforms of the Saudi Arabian Gulf, with the implication that this effect could be extended to improve the sustainability of important fishery resources.
The 1991 Gulf oil spill caused deleterious effects on the benthic fauna of northern Arabian Gulf.... more The 1991 Gulf oil spill caused deleterious effects on the benthic fauna of northern Arabian Gulf. The most heavily affected was the lagoons and bays located between Ras Al-Khafji in the north and Ras Abu Ali in the south. Manifa-Tanajib Bay System (MTBS), located within this affected area was studied in detail during 2006 to comprehend the status of macrobenthic communities fifteen years after oil spill. Benthic samples were collected from 25 locations (0.5 -8.5 m) of MTBS representing inner bay and outer bay regions. Post spill studies have reported the heavily polluted status in sediments (200 -10,000 mg kg -1 of Total Petroleum Hydrocarbons, TPH) in several locations of MTBS and the sediment-depth profile studies revealed that higher concentration was at 0-5 cm during 1993, while it was at 10-20 cm during 2002-2003. This study showed detectable levels of TPH in two stations only, one in inner bay and another in outer bay. Altogether, 39 macrobenthic taxa were recorded from the study area, of which, polychaetes comprised of 39% of the total individuals and were undergone detailed community structure analyses. Opportunistic polychaete/amphipod ratio (BOPA index) indicated high (80%) and good (20%) ecological status in the study area. Our results indicated that the benthic communities in the MTBS are devoid of any kind of stress from oil pollution. Fac, Oral
Marine Pollution Bulletin, 2012
The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gul... more The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15 years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14 years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients.
Journal of Micropalaeontology, 2005
This paper is the first contribution to the knowledge of pteropods in surficial sediments of the ... more This paper is the first contribution to the knowledge of pteropods in surficial sediments of the entire western continental shelf of India. Both qualitative and quantitative analyses of pteropod assemblages were carried out on 50 coarse fractions (>125 µm) of topmost portions of grab samples recovered along 12 transects covering the inner shelf to the upper slope (30-200 m water depths). The distribution of eight significant species was mapped. The resultant maps were correlated with the bathymetric, hydrographic and aragonite preservation conditions in the investigated area. This study reveals a bathymetric control over the distribution of Limacina inflata, Creseis acicula and Creseis chierchiae across the shelf. Furthermore, a marked difference in vertical salinity gradient from south to north along the shelf appears to have a profound influence on the abundance of these species. The pteropod shells in sediments of the northern offshore region with anoxic bottom conditions are generally well preserved, unlike the southern region, where oxygen concentration of the bottom water is relatively high enough to cause dissolution or even elimination of many shells of the most susceptible pteropods like C. acicula and C. chierchiae. The variation in the intensity of the oxygen minimum zone along the western continental shelf of India has significant influence upon the distribution pattern of Clio convexa.
Hydrobiologia, 2010
Taxonomic sufficiency (TS) has been used in impact assessment studies of various pollution effect... more Taxonomic sufficiency (TS) has been used in impact assessment studies of various pollution effects on marine benthic communities and found appropriate to identify the effects of pollution on marine communities. Cost, in terms of the expertise and time needed to identify organisms, increases with the level of taxonomic accuracy. Recently, TS has been adopted to study spatial patterns of macrobenthic community structure. In order to accept TS as a routine approach in wider benthic studies, it needs to be proved valid for various taxa and in geographically different areas. The present study investigates the value of TS in meiofaunal nematodes by analyzing an extensive data set based on samples collected from a wide geographical area covering a large depth gradient. For this study, samples were collected from every degree square of the western Indian continental shelf (7°-22°N latitudes). Our high resolution data showed that with increase in depth, nematode species richness and diversity decreased and communities showed significant variation between shallow and deeper waters. The present study tests whether lower taxonomic resolution nematode data can explain community shifts along a depth gradient in a similar way to species level data from the same data set. Meiofauna have often been neglected from benthic studies, and most attention has been given to macrofauna. This is mainly due to the difficulty in the taxonomic identification of meiofauna. The results of this study based on univariate and multivariate analyses support the use of family level data of nematodes to explain some aspects of depth variation in a similar way to species level data.
Estuarine, Coastal and Shelf Science, 2010
Keywords: Meiofauna free-living marine nematodes community structure depth variation a b s t r a ... more Keywords: Meiofauna free-living marine nematodes community structure depth variation a b s t r a c t Meiofaunal standing stock and nematode community structure were investigated in the western continental shelf of India by collecting samples from every degree square of the shelf during two cruises of the FORV (Fishery and Oceanographic Research Vessel) Sagar Sampada, conducted in 1998 and 2001. Samples were collected from 30, 50, 100 and 200 m depths using a Smith Mc Intyre grab. Meiofaunal density ranged from 8 Ind. 10 cm À2 to 1208 Ind. 10 cm À2 and biomass from 0.07 mg 10 cm À2 to 6.11 mg 10 cm À2 . Nematodes were the dominant meiofaunal group, contributing 88% of the density and 44% of the biomass. Harpacticoid copepods were the second important taxa, contributing 8% of both biomass and density. Altogether, 154 species of nematodes belonging to 28 families were recorded from the study area. Numerically, Desmodora spp., Dorylaimopsis sp., Tricoma spp., Theristus spp. and Halalaimus spp. were the dominant species. In general, there was a decrease in biomass and density of meiofauna and species diversity of nematodes with increase in depth. There was a 67% drop in species number from 51 to 100 m (106 species) to the shelf edge (35 species). Species richness and diversity indices showed consistent decrease with depth. The species dominance index was higher below 150 m depth. ANOSIM (from PRIMER) showed a significant difference between the nematodes of the near shore and shelf edge. Latitudinal variation was observed only in the number of nematode species. Biomass and abundance of nematodes were found to increase from coarse to fine sediment, while copepods showed an opposite trend. Multivariate analyses of nematode communities did not reveal any latitudinal or substratum differences. Variables such as depth, latitude, organic matter (OM) and amount of clay were the most relevant parameters influencing the biomass and density of meiofauna, while depth and temperature were the important parameters explaining the distribution of the nematode communities along the western Indian shelf.
Marine Pollution Bulletin, 2011
Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions.... more Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa-Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status of the macrobenthos in MTBS during 2006. This bay system is characterized by very shallow inner bays with elevated salinity and temperature compared to the rest of the bay area. As a result mainly of the hyper salinity, the inner bay communities are distinct from the outer bay communities. Overall, fairly high species richness with several rare species was observed. High Shannon-Wiener diversity values and ABC plots indicated the healthy status of the polychaete communities, while BOPA index indicated slightly polluted status in 20% of the stations. The oil sensitive amphipods were not completely re-colonized in 20% of the stations, even after 15 years of recovery from the 1991 oil spill.
MACROBENTHIC COMMUNITY STATUS 12 YEARS AFTER THE 1991 GULF OIL SPILL INCIDENT T.V. Joydas1*, Moha... more MACROBENTHIC COMMUNITY STATUS 12 YEARS AFTER THE 1991 GULF OIL SPILL INCIDENT T.V. Joydas1*, Mohammad A. Qurban1, Angel Borja2, P.K. Krishnakumar1, Abdulaziz Al-Suwailem3 1Center for Environment and Water, Research Institute, King Fahd University of Petroleum and Minerals, P. B. No. 1995, Dhahran–31261, Saudi Arabia, 2AZTI-Tecnalia; Marine Research Division; Herrera Kaia, Portualdea z/g, 20110 Pasaia, Spain, 3Marine Core Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. E-mail: tvjoydas@kfupm.edu.sa The Gulf war in 1991 resulted in the intentional discharge of an estimated 8–11 million barrels of crude oil into the Gulf and became the largest spill in history. The spill caused a drastic impact in the coastal areas located between Ras-Al-Khafji in the north and Abu Ali in the south of the Saudi Arabian coast. In Saudi Arabia, the greatest impact of the spill was visible in the nearshore region of the open water and in the sheltered inner bays. A consisten...
ICES Journal of Marine Science, 2015
Because of the increasing oil industry development in the Arabian Gulf, hundreds of oil and gas f... more Because of the increasing oil industry development in the Arabian Gulf, hundreds of oil and gas facilities have been installed in both offshore and inshore areas during the last few decades. However, no studies have been conducted till now on the influence of these platforms on the structure and composition of marine faunal assemblages. The present work addresses this issue to propose environmental management measures connected to the utilization of fishery resources. Offshore and inshore surveys were carried out along the Saudi Gulf waters using trawl and beach-seine nets, respectively. Data relative to only fish (offshore) and fish and invertebrates (inshore) were collected concurrently with several factors: density of oil and gas facilities (offshore), distance to the nearest coastal platform (inshore), oceanographic variables, and habitat characteristics. Results of offshore surveys indicated higher fish density-both total and of fishery resources-in locations with a higher number of oil and gas facilities within a 5 km radius, whereas biomass density was not significantly different. Hence, oil and gas facilities seem to serve as nursery areas for small fish. For inshore communities, more species and diversity were found in stations closer to coastal oil and gas facilities. In addition, among the five coastal embayments sampled, those with more oil and gas facilities had more species. The findings of the present work support the hypothesis of a positive net ecological role of oil and gas platforms of the Saudi Arabian Gulf, with the implication that this effect could be extended to improve the sustainability of important fishery resources.
The 1991 Gulf oil spill caused deleterious effects on the benthic fauna of northern Arabian Gulf.... more The 1991 Gulf oil spill caused deleterious effects on the benthic fauna of northern Arabian Gulf. The most heavily affected was the lagoons and bays located between Ras Al-Khafji in the north and Ras Abu Ali in the south. Manifa-Tanajib Bay System (MTBS), located within this affected area was studied in detail during 2006 to comprehend the status of macrobenthic communities fifteen years after oil spill. Benthic samples were collected from 25 locations (0.5 -8.5 m) of MTBS representing inner bay and outer bay regions. Post spill studies have reported the heavily polluted status in sediments (200 -10,000 mg kg -1 of Total Petroleum Hydrocarbons, TPH) in several locations of MTBS and the sediment-depth profile studies revealed that higher concentration was at 0-5 cm during 1993, while it was at 10-20 cm during 2002-2003. This study showed detectable levels of TPH in two stations only, one in inner bay and another in outer bay. Altogether, 39 macrobenthic taxa were recorded from the study area, of which, polychaetes comprised of 39% of the total individuals and were undergone detailed community structure analyses. Opportunistic polychaete/amphipod ratio (BOPA index) indicated high (80%) and good (20%) ecological status in the study area. Our results indicated that the benthic communities in the MTBS are devoid of any kind of stress from oil pollution. Fac, Oral
Marine Pollution Bulletin, 2012
The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gul... more The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15 years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14 years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients.
Journal of Micropalaeontology, 2005
This paper is the first contribution to the knowledge of pteropods in surficial sediments of the ... more This paper is the first contribution to the knowledge of pteropods in surficial sediments of the entire western continental shelf of India. Both qualitative and quantitative analyses of pteropod assemblages were carried out on 50 coarse fractions (>125 µm) of topmost portions of grab samples recovered along 12 transects covering the inner shelf to the upper slope (30-200 m water depths). The distribution of eight significant species was mapped. The resultant maps were correlated with the bathymetric, hydrographic and aragonite preservation conditions in the investigated area. This study reveals a bathymetric control over the distribution of Limacina inflata, Creseis acicula and Creseis chierchiae across the shelf. Furthermore, a marked difference in vertical salinity gradient from south to north along the shelf appears to have a profound influence on the abundance of these species. The pteropod shells in sediments of the northern offshore region with anoxic bottom conditions are generally well preserved, unlike the southern region, where oxygen concentration of the bottom water is relatively high enough to cause dissolution or even elimination of many shells of the most susceptible pteropods like C. acicula and C. chierchiae. The variation in the intensity of the oxygen minimum zone along the western continental shelf of India has significant influence upon the distribution pattern of Clio convexa.
Hydrobiologia, 2010
Taxonomic sufficiency (TS) has been used in impact assessment studies of various pollution effect... more Taxonomic sufficiency (TS) has been used in impact assessment studies of various pollution effects on marine benthic communities and found appropriate to identify the effects of pollution on marine communities. Cost, in terms of the expertise and time needed to identify organisms, increases with the level of taxonomic accuracy. Recently, TS has been adopted to study spatial patterns of macrobenthic community structure. In order to accept TS as a routine approach in wider benthic studies, it needs to be proved valid for various taxa and in geographically different areas. The present study investigates the value of TS in meiofaunal nematodes by analyzing an extensive data set based on samples collected from a wide geographical area covering a large depth gradient. For this study, samples were collected from every degree square of the western Indian continental shelf (7°-22°N latitudes). Our high resolution data showed that with increase in depth, nematode species richness and diversity decreased and communities showed significant variation between shallow and deeper waters. The present study tests whether lower taxonomic resolution nematode data can explain community shifts along a depth gradient in a similar way to species level data from the same data set. Meiofauna have often been neglected from benthic studies, and most attention has been given to macrofauna. This is mainly due to the difficulty in the taxonomic identification of meiofauna. The results of this study based on univariate and multivariate analyses support the use of family level data of nematodes to explain some aspects of depth variation in a similar way to species level data.
Estuarine, Coastal and Shelf Science, 2010
Keywords: Meiofauna free-living marine nematodes community structure depth variation a b s t r a ... more Keywords: Meiofauna free-living marine nematodes community structure depth variation a b s t r a c t Meiofaunal standing stock and nematode community structure were investigated in the western continental shelf of India by collecting samples from every degree square of the shelf during two cruises of the FORV (Fishery and Oceanographic Research Vessel) Sagar Sampada, conducted in 1998 and 2001. Samples were collected from 30, 50, 100 and 200 m depths using a Smith Mc Intyre grab. Meiofaunal density ranged from 8 Ind. 10 cm À2 to 1208 Ind. 10 cm À2 and biomass from 0.07 mg 10 cm À2 to 6.11 mg 10 cm À2 . Nematodes were the dominant meiofaunal group, contributing 88% of the density and 44% of the biomass. Harpacticoid copepods were the second important taxa, contributing 8% of both biomass and density. Altogether, 154 species of nematodes belonging to 28 families were recorded from the study area. Numerically, Desmodora spp., Dorylaimopsis sp., Tricoma spp., Theristus spp. and Halalaimus spp. were the dominant species. In general, there was a decrease in biomass and density of meiofauna and species diversity of nematodes with increase in depth. There was a 67% drop in species number from 51 to 100 m (106 species) to the shelf edge (35 species). Species richness and diversity indices showed consistent decrease with depth. The species dominance index was higher below 150 m depth. ANOSIM (from PRIMER) showed a significant difference between the nematodes of the near shore and shelf edge. Latitudinal variation was observed only in the number of nematode species. Biomass and abundance of nematodes were found to increase from coarse to fine sediment, while copepods showed an opposite trend. Multivariate analyses of nematode communities did not reveal any latitudinal or substratum differences. Variables such as depth, latitude, organic matter (OM) and amount of clay were the most relevant parameters influencing the biomass and density of meiofauna, while depth and temperature were the important parameters explaining the distribution of the nematode communities along the western Indian shelf.
Marine Pollution Bulletin, 2011
Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions.... more Shallow water bays located in the western Arabian Gulf experience harsh environmental conditions. Some of these bays, including Manifa-Tanajib Bay System (MTBS), were also exposed to the 1991 oil pollution event. This study investigates the status of the macrobenthos in MTBS during 2006. This bay system is characterized by very shallow inner bays with elevated salinity and temperature compared to the rest of the bay area. As a result mainly of the hyper salinity, the inner bay communities are distinct from the outer bay communities. Overall, fairly high species richness with several rare species was observed. High Shannon-Wiener diversity values and ABC plots indicated the healthy status of the polychaete communities, while BOPA index indicated slightly polluted status in 20% of the stations. The oil sensitive amphipods were not completely re-colonized in 20% of the stations, even after 15 years of recovery from the 1991 oil spill.