Feeding habits and trophic relationships of fishes utilizing an impacted coastal habitat, Singapore

Analysis of the feeding habits and trophic interrelationships between nine important fish species including Ambassis interruptus, Liza vaigiensis, Escualosa thoracata, Leiognathus decorus, Stolephorus indicus, Gerres oyena, Arius sagor, Sillago sihama and Ambassis kopsii utilizing an impacted coastal habitat revealed that the diets of most species underwent marked changes with ontogeny. Most of them had moderate food intake with fullness value ranging from 2.50–4.88. Variations of diet breadth and vacuity index were observed between species and size. New settlers of most species fed mainly on microcrustaceans especially calanoid copepods, before shifting to other food items. A multivariate analysis demonstrated that diet composition of the nine fish species differed from each other. However, significant overlaps between some fish species, including A. kopsii with G. oyena, E. thoracata with L. decorus, A. sagor with S. sihama and G. oyena with L. decorus, were detected by a Morisita-Horn index. This indicates that food partitioning with a slight competition among species occurs in this heavily impacted ecosystem.     

Community Structure of Coastal Fishes in Relation to Heavily Impacted Human Modified Habitats

Diversity and community structure of coastal fishes were compared between reforested mangrove and reclaimed sandy habitats at Pasir Ris, in the eastern part of Singapore. Both habitats supported a total of 91 species, but a single species, Ambassis kopsii dominated in abundance. Mean fish density was significantly higher at the reclaimed sandy shore than the reforested mangrove, but the reforested mangrove habitat yielded higher diversity. Apart from A. kopsii, abundant species in the mangroves included Ambassis interrupta, Thryssa hamiltonii, Acentrogobius sp., Scatophagus argus and Arius sagor. Anodontostoma chacunda, Acentrogobius sp., Leiognathus decorus, Sillago sihama and Stolephorus sp. were abundant in the reclaimed sandy habitat. Both habitats exhibited a higher mean density and average species richness during high tide. Several species from the family Gobiidae dominated the catch during low tide while pelagic fishes were most abundant during high tide. Diel variation showed significantly higher density during the day than at night, a result that contrasts to similar studies elsewhere. However, species richness showed no significant variation between day and night catches. Interaction between combined factors of time of the day and tidal height on fish density and average species richness was significantly different. The results indicated both habitat types to be important fish nurseries.     

Seasonal and spatial variations of fish trophic guilds in a shallow,semi-enclosed tropical estuarine bay

A study on seasonal and spatial variations of feeding habits and trophic guilds of dominant fish species in Pattani Bay during March 2003 to February 2004 was aimed at classifying diet composition, identifying dominant food components of each species, categorizing trophic guilds of the community and evaluating effects of habitat characteristics and seasonality on guild organization. Most fishes showed high food intake, fed on a diverse range of food items but relied heavily on calanoid copepods and shrimps. All species, with the exception of Epinephelus coioides, were classified as specialist feeders. Four main dietary guilds were classified. Three of these were classified as the guilds dominated by at least two major food items. Significant variations in trophic guilds of 28 fish species based on habitat types and seasons were also identified. They could be divided into three seasonal groups and three site-groups and a single site. Trophic organization for each season and habitat ranged from two to four groups. This information identifies groups of fishes that seasonally and spatially utilize different food resources within a semi-enclosed estuarine bay ecosystem.     

Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp-fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay.     

Feeding ecology of two sillaginid fishes and trophic interrelations with other co-existing species in the southern part of South China Sea

Feeding ecology of Sillago sihama and Sillago ingenuua and interrelationship with other 15 fish species, including Stolephorus commersonii, Escualosa thoracata, Lutjanus russelli, Terapon puta, Ambassis kopsii, Ambassis vachellii, Dendrophysa russelli, Gerres filamentosus, Leiognathus decorus, Leiognathus splendens, Leiognathus equulus, Thryssa hamiltonii, Carangoides praeustus, Lethrinus lentjan, and Pomadasys maculatum, utilizing coastal waters off the southern part of the South China Sea were investigated. Dietary contents from 4308 guts of those species collected during July 2003–May 2005 were examined. They were significantly grouped, based on similarity coefficient, into five feeding clusters (P < 0.01). Of these, most of the diets were dominated by calanoid copepods, shrimps, polychaetes and gammarid amphipods. Comparative study on two sillaginid species showed that both Sillago sihama and Sillago ingenuua were carnivores fed mainly on polychaetes and other benthic organisms. Dietary ontogenetic change of Sillago sihama was very distinctive where small sized classes started feeding mainly on calanoid copepods before changing almost completely to polychaetes. The two species applied both sharing and partitioning strategies for food, depending on size classes, to live with each other.