Twelve new records of Coral associated fish from the Saint Martin’s island based on morphometric and molecular approaches

The study was conducted to know the diversity of coral associated fishes of the Saint Martin Island from December 2017 to April 2019. A total of 46 coral associated marine fish species were recorded, among them 12 species; sunajtuLiughcliug , Lutjanus russellii, Parupeneus indicus, Siganus sutor, Thalassoma lunare, Gazza achlamys, Pomadasys andamanensis, Pomadasys kaakan, Lethrinus crocineus, Argyrosomus regius, Istigobius ornatus and Cryptocentrus cyanotaenia under six family were newly recorded from this Island. We assume that there are more species to be explored and need proper management strategy for conservation of coral reef and its associated biodiversity. Bangladesh J. Zool. 48(2): 253-262, 2020

Coastal fish diversity of the Socotra Archipelago, Yemen

The Socotra Archipelago, located in the eastern Gulf of Aden, has a unique marine environment which combines tropical and ‘pseudo-temperate’ elements. Studies on the fish biogeography of the archipelago, partially framed in regional studies, have substantially outpaced critical elementary research on the archipelago’s fish diversity. The present study seeks to close this gap and identifies the Socotra Archipelago as a major hotspot of coastal fish diversity in the Indian Ocean. The archipelago supports unique coastal fish assemblages which are predominantly composed of coral-associated (“reef”) species, in spite of the limited biogenic reef frameworks. A Preliminary Checklist comprises 682 species with confirmed records and a “Working List” includes an additional 51 records, totalling 733 faunal records in 108 families. The family Labridae is the most speciose, followed by Gobiidae, Pomacentridae, Serranidae and Chaetodontidae. The species richness of the archipelago is the highest when compared to adjacent Arabian ecoregions. The richness of the Acanthuridae, Chaetodontidae, Labridae, Pomacentridae and Pseudochromidae stand out as particularily high, and the richness of several families is as high as or higher than in the entire Red Sea. The total archipelagic richness is extrapolated at up to 875 species based on incidence-based richness models and expert opinion. Inshore fish inventories, covering 497 species, found between 14 and 132 species per site (x̄ = 66). Site diversity decreased across the archipelago from west to east and from north to south. Total fish diversity was highest around Socotra Island, followed by Abd al-Kuri & Kal Farun and Darsa & Samha. Occurrence frequencies were very unevenly distributed and dominated by Pomacentrus caeruleus and Thalassoma lunare, whilst many species were infrequent. The fish assemblages are dominated by species from the Indo-West Pacific and the north-western Indian Ocean. The assemblages are rich in rare species and hybrids, and include a low number of endemics (4–5), and a high number of species with far-reaching and Western Indian Ocean ranges.

Patterns of pisciviory by resident predatory reef fish at One Tree Reef, Great Barrier Reef

Patterns of piscivory were investigated among five abundant species of predatory fish at One Tree Reef, Great Barrier Reef, Australia. The guts of two lutjanids Lutjanus carponotatus and Lutjanus fulviflamma, two labrids Cheilinus diagrammus and Thalassoma lunare, and a serranid Epinephelus quoyanus were examined for type, length, number and volume of prey at two times of the day: sunrise and sunset. Each of these species consumed fish, but only T. lunare and the two lutjanids consumed recruit-sized fish. This information is important because there is often scepticism as to whether large predators (>200 mm TL) such as lutjanids consume new recruits. Only in the lutjanids were there differences in the number and volume of prey present in the gut at sunrise and at sunset; at sunset, few lutjanid specimens contained prey, whereas at sunrise 98% of specimens contained prey. This result, in conjunction with studies of nocturnal activity, suggest that patterns of predation pressure inferred from daylight observations of predator abundance may have little relevance to actual patterns of predation at local scales.

Comparison of methods for sampling ectoparasites from coral reef fishes

Methods for sampling ectoparasite assemblages were compared using 7 species of coral reef fishes (Acanthochromis polyacanthus, Thalassoma lunare, Ctenochaetus striatus, Chlorurus sordidus, Scolopsis bilineatus, Hemigymnus melapterus, and Siganus doliatus). Estimates of total numbers and composition of ectoparasites were dependent on post-collection handling techniques and the method of ectoparasite removal. Fish were enclosed within plastic bags under water at the point of capture. Filtration of water from the plastic bags revealed a large number of parasites (mainly gnathiid isopods) that had detached from the host on capture. A subsequent sea-water rinse removed a large number of ectoparasites, but further treatment with the anaesthetic chloretone released additional individuals. The few remaining parasites were removed by visual inspection. A chloretone bath was more effective than a sea-water bath at removing parasites. The species composition of parasites recovered by a chloretone bath plus a visual survey was different from that recovered with a sea-water bath and visual survey; this suggests that traditional scanning techniques may not detect all parasites.