Influence of habitat heterogeneity on the assemblages and shell use of hermit crabs (Anomura: Diogenidae)

Background Two contrasting intertidal habitats on the western Sabah coast (Malaysia), one is a rocky-sandy-mud flat at Sepangar (N6°02′18.57″; E116°06′40.07″) and the other is a mangrove foreshore at Sulaman (N6°15′33.00″; E116°18′49.80″), are characterized by substrate zonation and homogeneous substrate (mud), respectively. Hermit crabs are one of the most conspicuous benthic macrofauna at both sites. The study examined the influence of habitat heterogeneity on the assemblages and shell use pattern of hermit crabs. Results The heterogeneous intertidal flat at Sepangar (five species) supported a higher diversity and abundance of hermit crabs compared to Sulaman mangrove foreshore (two species). Hermit crabs at Sepangar used a greater variety of shells (30 species) compared to those at Sulaman (two species). Zonation of hermit crab species occurred at Sepangar where Diogenes klaasi dominated at the high-tide mark and two Clibanarius species (C. striolatus and C. merguiensis) dominated at the low-tide mark. Considerable overlap in habitat use (mid- and lower shore) occurred between D. tumidus and the two Clibanarius species which appeared to influence shell use pattern. Conclusions This study supports the work of others showing that structurally complex habitats will allow habitat partition among species thus explaining the greater diversity and abundance of hermit crabs. Such a heterogeneous habitat provides a wider choice of shells for the hermit crabs, minimizing interspecific competition for the available shell resources

Abundance, placement and sexual identity of the epizoic barnacle Chelonibia testudinaria relative to the size and species of host turtles in Mabul Island, Malaysia

Sea turtles are partners in commensal relationships with a variety of epibionts, including barnacles. The acorn barnacle Chelonibia testudinaria is one species commonly found associated with sea turtles and other marine fauna throughout temperate to tropical waters including the Indo-Pacific. We conducted a study to assess the occurrence of this barnacle, relative to host life stage and species in a mixed foraging population of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles ( juvenile, sub-adult, adults (female and male)) in Mabul Island, Sabah, Malaysia (Celebes Sea). Expecting similar relative abundance by life stage, we found instead a significant effect between the combined dependent variables (abundance and size of barnacles) and the life stages of sea turtles in Mabul after controlling for the covariates of size and species of sea turtles (F(8, 428) = 5.77, P < 0.001, Pillai = 0.19). Among green turtles with barnacles, though adult males had larger barnacles compared with the female turtles, the mean barnacle abundance on adult females (43.4 individuals ± 5.19 SD) was higher than all other life stages. Most of the barnacles (85.6%; N = 1931) were found on the plastron of the sea turtles. The highest number of barnacle reacquisition was found among the juvenile turtles. In assessing the complemental males of the barnacles, we found they were consistently attached to the shells of the larger of the hermaphrodites from each region of the host’s body despite average shell-size differences with each region

Coral reef fish population in the western extremity of the Coral Triangle

The central and north west coast of Sabah lies along the western extremity of the Coral Triangle, within which are situated several marine protected areas (MPAs). In the present study we determined in situ coral reef fish populations in several localities along the west coast of Sabah, by exploring species abundance, richness and diversity of ten economically important fish species. The underwater surveys were conducted from May to December 2015. During this eight- month period, surveys at each site were undertaken once every two months. Dives were conducted during the daylight hours. A total of 171 individuals from the targeted fish species were enumerated from the 349 still images and 220 minutes of video footage. Abundance was observed mainly in the semi-protected MPA (n=110) with only one fish species recorded with more than 2 individuals at protected MPA and unprotected sites. We observed a correlation between fish species richness and coral topographic complexity, with study sites at the semi-protected MPA having the most complex topography landscape, and accordingly recording the highest Shannon-Wiener index (H= 2.85). Higher abundance recorded at study sites in the unprotected sites and semi-protected MPA indicate that such areas could potentially become de facto MPAs. A long-term monitoring, assessment and evaluation of the multiple degrees of variables involved such as length-weight relationship, type of habitat, variation in depth, and species behaviour are recommended in order to understand better the relationship and dynamics between these variables

An Assessment of the Carrying Capacity of Sipadan Island Park, Sabah, Malaysia

Sipadan Island is a small oceanic island in Malaysia, and renowned as one of the world’s top ten dive destination. However, it was only recently that the island was gazetted as a Marine Protected Area. The aim of this study is to assess the carrying capacity of Sipadan Island Park. The objectives are to enumerate diver and dive frequency, and to record the presence and sighting rate of iconic fishes in each of the 11 established dive sites on Sipadan. The study was carried out monthly over a 12-month period in 2011 and 2012. In that period, we recorded a total of 66,243 dives, of which, more than one third (35%; n=23,215 dives) was in Barracuda Point alone. In comparison, the least popular dive site - West Ridge–North Point - recorded just 154 dives. Thus, Barracuda Point, along with three other sites are found to have greatly exceeded the carrying capacity of a dive site. Iconic fishes are present throughout the year, and their sighting rate was similar in all months (p>0.05). However, our data showed a significant correlation between popular dive sites and sightings of iconic fish (p<0.05)

Consolidated Checklist of Hard Corals of the Genus Acropora Oken, 1815 (Scleractinia: Acroporidae) in North Borneo, East Malaysia

Acropora is the most biologically diverse group of reef-building coral, and its richness peaks at the Indo-Malay-Philippine Archipelago, the centre of global coral reef biodiversity. In this paper, we describe the species richness of Acropora fauna of North Borneo, East Malaysia, based on review of literature and as corroborated by voucher specimens. Eighty-three species of Acropora are reported here; four species are literature based and 79 are supported by voucher specimens that were subsequently photographed. New records for North Borneo were recorded for 12 species, including Acropora suharsonoi Wallace 1994 that was previously thought to be confined to a few islands along Lombok Strait, Indonesia. The diversity of Acropora in North Borneo is comparable to that of Indonesia and the Philippines, despite the area’s smaller reef areas. This further reinforces its inclusion as part the global hotspot of coral biodiversity

Marine profiling of Marudu Bay: Southwest Monsoon

Marudu Bay is a semi-enclosed bay located in the northernmost part of Sabah. It is located within the Tun Mustapha Park, and is a part of Malaysia’s Coral Triangle. The primary aim of this study is to gather information for the marine profiling of Marudu Bay, including its coastline, during the northeast monsoon. However, due to unavoidable delays, surveys were conducted during the southwest monsoon. Thus, the surveys were conducted between June and December 2015, which coincided with the southwest monsoon. During this season, most afternoons are defined by rain beginning late October. In this report, we present the result of a comprehensive review of literature on the biota (fishes, marine invertebrates, other aquatic vertebrates i.e. marine mammals and marine reptiles, corals and coral reef indicators, seagrasses and mangroves) and abiotic factors (oceanographic parameters, water quality and marine pollutants) of Marudu Bay, and the results of the field surveys within the Bay. The primary database (raw data) of the biodiversity studies are appended to this report as an excel spreadsheet, and photographs of the species observed as jpeg files copied on to a compact disc. Generally, we recorded higher species diversity for the fishes (188 spp.), marine invertebrates (35 spp.), hard corals (168 spp.), seagrasses (4 spp.) and mangroves (26 spp.), compared to other previous studies. On the status of mangrove forests, mangrove species composition in Marudu Bay varies between the three surveyed areas: Kudat (5 species), Marudu (11 and 10 species in Sg. Matunggong and Bandau, respectively) and Pitas (18 species). The species include both mangrove-associated species and true mangrove species. Sungai Telaga in Pitas is also the location of Malaysias’ largest but also controversial shrimp aquaculture farm. The farm is estimated to be at least 1,000 hectares, which is largely sited within a virgin mangrove forest. On the status of green mussel population, recent studies suggests the high relative abundance of phytoplankton Chaetocerotaceae in the Marudu Bay as the main limiting factor to the growth of the green mussels

First record of jellyfish Anomalorhiza shawi Light, 1921 (Cnidaria: Scyphozoa) and its associated organisms in Sabah, Malaysia

The present study describes a first record of the jellyfish Anomalorhiza shawi Light, 1921 from Malaysia. It belongs to the family Lychnorhizidae Haeckel, 1880, order Rhizostomeae Cuvier, 1799 (Cnidaria: Scyphozoa). The specimen was taken from Sepanggar Bay, Kota Kinabalu, off the Universiti Malaysia Sabah (UMS) Jetty by manual collection with a bucket. The size of the bell was 430 mm in diameter with oral arms measuring 290 mm in length including the brown terminal clubs, which differentiates A. shawi from other congeners of the family. Anomalorhiza shawi belongs to the monotypic genus Anomalorhiza, and was first reported from the Philippines, with later reports from Hawaii and Thailand. In addition, A. shawi was found associated with other organisms such as the silver shad, Alepes vari (Cuvier, 1833) (Carangidae), and the crab Charybdis feriata (Linnaeus, 1758) (Portunidae). The association between jellyfish and other organisms have been discussed here. A checklist is provided for the current species of scyphozoan jellyfish reported from Malaysia

Turbid reefs experience lower coral bleaching effects in NE Borneo (Sabah, Malaysia)

The impacts of climate change are becoming more evident in recent years. Future projections suggest that heat stress events will likely be more frequent and severe over the next century, threatening the high diversity of the Coral Triangle. Shallow turbid reefs may help dampen some of these effects as several studies have shown their inherent resilience to heat stress events. Therefore, our main goal was to test this hypothesis by assessing the response of corals to the heat stress event of 2020. We conducted bleaching surveys in two contrasting habitats in Darvel Bay, Sabah: the turbid reef of Sakar, and the clear-water reef of Blue Lagoon. Relatively high coral cover (40-43%) was observed on both reefs in 2019. Underwater data loggers were used to monitor temperature and light. Coral colonies were scored from video transects of 100m at 5m and 10m depth in both localities, with an additional transect at 15m depth in Blue Lagoon. A total of 1,326 coral colonies were evaluated for bleaching presence and bleaching severity based on the six-point scoring method. Bleaching severity varied significantly between both reefs. Low bleaching impacts were observed in the high turbid reef, with an average of 9.6% of colonies having bleached. Meanwhile, the clear-water of Blue Lagoon had an average of 37.1% of coral colonies affected by bleaching. Bleaching severity also varied significantly among depth, where corals in deeper depths bleached less in Blue Lagoon. Foliose coral forms were most affected in Blue Lagoon, while massive coral forms suffered the most in Sakar reef. Bleaching responses were also significantly different among coral genera. While Ctenactis and Herpolitha were consistently resistant in both reefs, Leptoseris, Fungia and Goniopora were most affected in the 5m of Blue Lagoon. Meanwhile, Pachyseris was notably more affected in Sakar reef at 10m than in Blue Lagoon. Overall, bleaching indices within these two reefs are lower than most that were assessed around the globe during heat stress events in 2020. These outcomes support the hypothesis of turbid reefs hosting resilient coral communities in the face of climate change