Food partitioning of two co-occurring Terapontid fishes, Terapon jarbua and Pelates quadrilineatus, in coastal areas of Trang Province, Southern Thailand

This study clearly demonstrates that Terapon jarbua and Pelates quadrilineatus showed obvious food partitioning by their dietary ontogenetic changes. The larvae of both species fed mainly on the calanoid copepods. Juveniles of T. jarbua shifted to feed mainly on harpacticoid copepods, crabs and fish scales. Juveniles of P. quadrilineatus shifted to fed mainly on harpacticoid copepods and Lucifer spp. Adult fish shifted to fed on larger prey size. AdultT. jarbua fed mainly on fish and fish scales while adult of P. quadrilineatus fed mainly on large benthic animals, amphipods, bivalves, hermit crabs and polychaetes. The study on morphology and feeding structure development indicated that, the development of mouth, jaw, teeth, gill raker and intestinal length were important ontogeneticchange in the diet of fish. The ontogenetic change in the diet was the important strategies to reduce competition between these two coexisting species in coastal area of Trang Province

Influence of environmental variables on the abundance of estuarine clam Meretrix casta (Chemnitz, 1782) in Trang Province, Southern Thailand

The estuarine clam Meretrix casta (Chemnitz, 1782) is an edible bivalve that burrows into bottom sediment to protectitself from environmental fluctuations and predation. This study examined the relationship between clam populations andabiotic environmental conditions in order to develop an understanding of the biological and ecological processes that couldbe used to improve their management and exploitation. The study site was located in the estuary of the Palian River, KantangDistrict, Trang Province, on the Andaman coast of Thailand. Six zones were established along the estuary. Data werecollected from January 2008 to December 2008. The results showed that salinity (Sal) and concentrations of total suspendedsolids (TSS) were the water quality parameters most closely related to population densities of estuarine clams. The combinationof those variables gave the strongest correlation to clam densities (Spearman rank correlation, pw = 0.504). Among bottomsediment parameters, pH and ferrous and ferric iron concentrations gave the strongest correlations to clam densities(Spearman rank correlation, pw = 0.716). The result revealed that the water quality (Sal and TSS) and the bottom sediment(pH, ferrous and ferric iron) were the main significant parameters influencing the abundance of estuarine clam M. casta

Systematics of the combtooth blenny clade Omobranchus (Blenniidae: Omobranchini), with notes on early life history stages

Gibbs, Sean, Hundt, Peter J., Nelson, Andrea, Egan, Joshua P., Tongnunui, Prasert, Simons, Andrew M. (2018): Systematics of the combtooth blenny clade Omobranchus (Blenniidae: Omobranchini), with notes on early life history stages. Zootaxa 4369 (2): 270-280, DOI: https://doi.org/10.11646/zootaxa.4369.2.

Phylogenetic analysis of trophic niche evolution reveals a latitudinal herbivory gradient in Clupeoidei (herrings, anchovies, and allies)

Biotic and abiotic forces govern the evolution of trophic niches, which profoundly impact ecological and evolutionary processes and aspects of species biology. Herbivory is a particularly interesting trophic niche because there are theorized trade-offs associated with diets comprised of low quality food that might prevent the evolution of herbivory in certain environments. Herbivory has also been identified as a potential evolutionary "dead-end" that hinders subsequent trophic diversification. For this study we investigated trophic niche evolution in Clupeoidei (anchovies, sardines, herrings, and their relatives) and tested the hypotheses that herbivory is negatively correlated with salinity and latitude using a novel, time-calibrated molecular phylogeny, trophic guilds delimited using diet data and cluster analysis, and standard and phylogenetically-informed statistical methods. We identified eight clupeoid trophic guilds: molluscivore, terrestrial invertivore, phytoplanktivore, macroalgivore, detritivore, piscivore, crustacivore, and zooplanktivore. Standard statistical methods found a significant negative correlation between latitude and the proportion of herbivorous clupeoids (herbivorous clupeoid species/total clupeoid species), but no significant difference in the proportion of herbivorous clupeoids between freshwater and marine environments. Phylogenetic least squares regression did not identify significant negative correlations between latitude and herbivory or salinity and herbivory. In clupeoids there were five evolutionary transitions from non-herbivore to herbivore guilds and no transitions from herbivore to non-herbivore guilds. There were no transitions to zooplanktivore, the most common guild, but it gave rise to all trophic guilds, except algivore, at least once. Transitions to herbivory comprised a significantly greater proportion of diet transitions in tropical and subtropical ( 35 degrees). Our findings suggest cold temperatures may constrain the evolution of herbivory and that herbivory might act as an evolutionary "deadend" that hinders subsequent trophic diversification, while zooplanktivory acts as an evolutionary "cradle" that facilitates trophic diversification