Review of range extensions of tropical brachyuran crabs into temperate waters of southern Africa

We compiled known occurrence records of seven species of crabs identified in the literature and one documented in this report as having undergone range extensions in southern Africa. Of these eight species, six (Austruca occidentalis, Neosarmatium africanum, Ocypode ceratophthalmus, Portunus segnis, Tubuca urvillei, and Varuna litterata) have extended their ranges either across a major biogeographic boundary that separates the subtropical and warm temperate ecoregions of this coast, or into estuaries that historically lack mangrove forests. For the seventh and eighth species, Charybdis smithii and Scylla serrata, we were unable to find any distributional data that supported poleward range extension. In addition, we contribute the first record of the blue swimming crab, P. segnis, from the temperate south coast of South Africa. This early detection is likely to be part of an ongoing regional trend of tropical-adapted brachyuran crab species extending their ranges into temperate ecoregions.

Species richness and longitudinal distribution of crustaceans in the Logawa River, Banyumas, Indonesia

Sastranegara MH, Kusbiyanto, Pulungsari AE. 2020. Species richness and longitudinal distribution of crustaceans in the Logawa River, Banyumas, Indonesia. Biodiversitas 21: 5322-5330. The Logawa River originates in a forest on Slamet Mountain and empties into the Serayu River. In this river, crustaceans play an important role as river macrobenthos. This research aimed to evaluate the species richness and longitudinal distribution of crustaceans. The research method was a stratified random sampling technique at eight stations with five replicates. Crustacean samples were collected using a Surber net, and water samples were taken with a water sampler. The results showed that there were six species of Decapoda in the river. Of these six species, three were shrimps and three were crabs. In longitudinal distribution, the shrimp Macrobrachium idae could be categorized as a cosmopolitan species that inhabited all stations, although there were several river branches before Stations IV (Cangkring Stream), V (Mengaji Stream), and VI (Banjaran Stream), bedrock substrate at Station I, high ammonia at all stations and high chemical oxygen demand (COD) between Stations IV and VIII. The crab Varuna litterata was found only at Station VI. In general, the species richness decreased after Station IV due to COD from the riverside. This was caused by human activities such as stone and sand excavation and overfishing in the habitat. The upstream habitat with its bedrock substrate was not suitable for decapods, except for cosmopolitan species.

Diversity and density of crabs in degraded mangrove area at Tanjung Panjang Nature Reserve in Gorontalo, Indonesia

Lapolo N, Utina R, Baderan DWK. 2018. Diversity and density of crabs in degraded mangrove area at Tanjung PanjangNature Reserve in Gorontalo, Indonesia. Biodiversitas 19: 1154-1159. This study was aimed to analyze the diversity and the density ofcrabs in a degraded mangrove area including in the intact mangrove area and the fishponds (the degraded mangrove area).. The datafrom this study could be used as supporting data for decision makers to slow down the degradation of mangrove along the area ofTanjung Panjang Natural Reserve. The observed data i.e diversity and density of crabs were collected using the stratified randomsampling method (10 m x 10 m plot). Environmental parameters suited to crab habitat were also measured. The samples were takenfrom 18 spots. The study shows that 20 species of crabs were obtained within the mangrove area, and 11 species were founded withinthe fishponds area. Interestingly, two species of crabs i.e Varuna yui and Varuna litterata were only founded in fishponds area. Thedensity of crabs in mangrove area ranged between 3.23 ind/300m2 and 4.52 ind/300m2, while the density of crabs in fishponds arearanged between 0.16 ind/300m2 and 0.63 ind/300m2. Further study revealed that characteristics and the age of mangrove trees affectedmacrozoobenthic biota (Gastropods, Bivalvia, Mud Lobster, Polychaeta, and shrimp) as well as fish diversity within mangrove inTanjung Panjang Natural Reserve. These may be important for further restoration program of mangrove ecosystem and the sustainablerestocking for conservation purposes.