Ephrime B. Metillo

First Record of Association of Copepods with Highly Venomous Box Jellyfish Chironex, with Description of New Species of Paramacrochiron (Cyclopoida: Macrochironidae)

Paramacrochiron chironecicola n. sp. (Copepoda: Cyclopoida: Macrochironidae) is described from the highly venomous box jellyfish Chironex sp. collected from Malampaya Sound, Palawan Island, The Philippines. This is the first record of copepods associated with cubozoan medusae, although other cnidarian groups such scyphozoans, hydrozoans, and anthozoans are common hosts for symbiotic copepods. The infection sites were on the subumbrella, pedalium, and rhopalium, but also rarely on the adradial furrow. The new species is distinguished from other congeners by a combination of the following features: (1) the fifth pedigerous somite dorsally covering the anterior part of the female genital double-somite; (2) the fine structures of the antenna (relative lengths of segments) and maxilliped (positions of terminal elements) of the female; (3) the relatively long outer spines on the exopodal segments of legs 1–4; (4) the relatively long and thick female leg 5 bearing a long protopodal seta which reaches to the distal margin of the exopod; (5) the relatively short caudal ramus in the female; and (6) the plump prosome and short urosome in the male. Since members of the genus typically parasitize scyphozoans, especially rhizostomes, the association of this parasitic copepod on cubozoans may reflect the relatively close phylogenetic relationship between cubozoans and scyphozoans.

Fatty Acid Profiling of Commercially Important Raw and Boiled Seer Fish Scomberomorus commerson (Lacepede, 1800) (Scombridae, Teleostei, Pisces)

The present study aims to determine the fatty acid profiling of commercially important fresh and boiled Scomberomorus commerson. Fatty acids in fresh and boiled fish were separated and quantitatively determined by gas chromatography–mass spectrophotometer using standard methods. The findings revealed that the predominant fatty acids in fresh S. commerson were octadecanoic acid methyl ester, octanoic acid, 1,2-benzenedicarboxylic acid and 3-cyclopentylpropionic acid representing respectively 45.91, 5.69, 6.75 and 8.65% of total fatty acids. Boiled S. commerson showed predominant changes in their fatty acid profiles. In the omega-3 and omega-6 families the dominant fatty acids were doconexent, 3-cyclopentylpropionic acid, octadeconoic acid methyl ester and Hexadecane representing respectively 3.87, 12.08, 44.26 and 3.11% of total fatty acids. After boiling, some fatty acids present in fresh fish are damaged and formed new fatty acids which belonged to ω-3 polyunsaturated fatty acids (PUFA). Boiling increased the concentration of PUFAs from 73.25 to 80.37% of total fatty acids and also formed new fatty acids.

Prevalence of cymothoid isopods (Crustacea, Isopoda) and proximate analysis of parasites and their host fishes, Southeastern India

Cymothoid isopods (Crustacea, Isopoda) are considered as potential threat to the health of different fish species. In order to evaluate the prevalence and proximate analysis of Cymothoid isopods and its host, an investigation was carried out fish species belonging to families Hemiramphidae and Belonidae in the Palk Bay region, Southeastern India. A total of 1265 individuals of teleost fish belonging to family Hemiramphidae species, Hemiramphus far (462), H. archipelagicus (78), and H. lutkie (277) and another family Belonidae species, Tylosurus crocodilus (448), were examined for cymothoid ectoparasitic infestation. Prevalence in H. far was the highest (39%) for the cymothoid Mothocys plagulophora, while T. crocodilus was most infested (13%) with Mothocys renardi, H. far and H. lutkie were not infested by M. renardi while T. crocodilus was not infested by M. plagulophora. Proximate analysis showed reduced level of protein in parasite infested fish compared with non-infested individuals. However, carbohydrate and lipid concentrations were lower in infested fish than non-infested individuals. Proximate analysis values in the two parasites of Mothocys species were similar, and these values were comparable to those unaffected fish species indicating that parasites were well nourished. The proximate analysis of isopod parasite M. plagulophora showed 21.6 ± 7.7, 1.26 ± 0.05, 5.49 ± 1.06% of protein, carbohydrate and lipid respectively, and in M. renardi, 21.09 ± 6.6, 1.32 ± 0.12, 5.83 ± 0.72% of protein, carbohydrate and lipid respectively. Cadmium levels were similar between affected and non-affected fish individuals and among species. The Pb levels were comparable among all T. crocodilus individuals, but the levels of Cd not showed much variation between affected and unaffected individuals in all four fish species.

Stable C and N isotope analysis elucidated the importance of zooplankton in a tropical seagrass bed of Santiago Island, Northwestern Philippines

ABSTRACT The role of zooplankton in a tropical seagrass ecosystem was investigated in milkfish farms pollution-impacted and -unimpacted seagrass beds in Santiago Island coral reefs, Northwestern Philippines. The aim was to compare between the two sites: (1) abiotic factors and zooplankton community parameters, and (2) the trophic structure using C and N stable isotopes. Low water (98–119 mV) and sediment (–121 to −138 mV) Oxidation Reduction Potential values indicated a reducing environment in the impacted site. Zooplankton in the impacted site showed the typical community response to eutrophication (low diversity, but high total abundance due to the dominance of the cyclopoid copepod Oithona oculata), generally few elevated δ15N values, but a significant shift towards depleted 13C due to the organic enrichment of fish-farm feeds. Apart from suggesting a highly complex food web with POM and zooplankton as main food sources in the unimpacted site, the Bayesian mixing model simulation generated reduced complexity in feeding interactions between basal sources, zooplankton, and fish including adults of a key fish species, Siganus fuscescens, in the impacted sites. In this study, C and N stable isotope analysis has clarified the importance of zooplankton as fish prey in a seagrass bed food web.

Diel patterns of Zooplankton community structure in nearshore waters of different substrates off Tinggi and Sibu Islands, Malaysia, with special reference to Copepods

The relationship between zooplankton community structure and selected environmental conditions was investigated by simultaneous two-day consecutive sampling in the waters overlying coral and sand sites off Sibu Island and a seagrass site off Tinggi Island, Johor, Malaysia. A total of 129 taxa were identified, 60 non-copepod taxa and 69 copepod species in all samples. Uni- and multi-variate analyses reveal distinct coral, sand, seagrass copepod assemblages with indicator copepod species and attributes of their size fractions. Small fraction (100–335 µm) samples contained greatest number of individuals, few rare species and were densest at onshore depths, and the opposite for large fraction (>335 µm) samples but were densest at nighttime and most species rich in the coral site at night. Higher species diversity at offshore stations is due likely to ecotonal effects of overlapping oceanic and nearshore communities. This study demonstrates the usefulness of uni- and multi-variate analyses in identifying patterns in zooplankton community structure in representative shallow tropical habitats, and the need for accurate zooplankton taxonomy, nighttime and daytime and onshore and offshore sampling, and size fractionation of samples.

Observations on the specific associations found between scyphomedusae and commensal fish and invertebrates in the Philippines

Our observations on scyphomedusae from selected Philippine embayments identified specific animals commensal with five species of rhizostome scyphomedusae, Acromitoides purpurus, Mastigias sp., Phyllorhiza punctata, Rhopilema hispidum and Versuriga anadyomene. Acromitoides purpurus medusae harbor the crab Charybdis feriata, the carangid fish Alepes djedaba and the poecilostomatoid copepod Paramacrochiron sp. The carangid A. djedaba was an associate of the blue morph of A. purpurus and Rhopilema hispidum in Panguil Bay. A black-pigmented Alepes sp. was found associated with burgundy A. purpurus medusae in Carigara Bay. Charybdis feriata juveniles are common commensals of all morphs of A. purpurus, R. hispidum and P. punctata medusae. Only the zooxanthelate Mastigias sp. lacked animal symbionts. We invoke the “meeting-point hypothesis” and the general theory of fish aggregation to floating structures to explain fish symbiosis with their medusan hosts. The invertebrate-medusa associations are attributed to feeding behaviors and predator avoidance by resident commensals. This study provides record of the poorly studied scyphozoan species and their association with animals in Philippine waters. Finally, we discuss the potential reasons why the golden spotted jellyfish, Mastigias sp., appears to lack animal commensals.

Feeding ecology of two sympatric species of Acetes (Decapoda: Sergestidae) in Panguil Bay, the Philippines

Sergestid shrimps of the genus Acetes are important in global shrimp fisheries and nearshore food-webs. The feeding habits of the sympatric species Acetes erythraeus and A. intermedius from Panguil Bay, Philippines were studied using gut contents and stable isotopes analyses. Both species are omnivorous suspension feeders of plankton, macrophyte detritus, and amorphous particulate organic materials. However, the diet of adults and juveniles differed by prey type. Gut fullness differed over 24h with a night-time peak in A. erythraeus and morning and midnight peaks in A. intermedius. Over 1 year gut fullness peaked during July to September for both species, with a minor peak during January for A. intermedius. Stable isotope analysis revealed similar δ15N values, but both species showed ontogenetic and interspecific separation of δ13C. A. erythraeus seemed to assimilate highly depleted carbon food sources by mangrove-based detrital and plankton trophic pathways, whereas A. intermedius relied on plankton and macroalgal and seagrass detrital pathways. These trophic differences may be mechanisms of partitioning the feeding niche, but allotopy in the two species with A. erythraeus confined to more brackish waters and A. intermedius dwelling in more saline marine waters may indicate that habitat niche segregation underlies these contrasting carbon trophic pathways.