Content area
Full Text
Abstract. The province of Camarines Norte has been producing Kappaphycus seaweed since the 1970s, becoming the leading producer in the Bicol Region. However, the occurrence and habit of shore crabs within seaweed farms have not yet been previously recorded. Assessment of shore crabs in seven seaweed farms was conducted for one year. Snorkeling surveys were conducted to record the occurrence and observe the habits of shore crabs on seaweed floaters. Additionally, field interviews with 110 seaweed farmers were carried out to obtain data on floater utilization, farm size, and planting season. Results showed a total of 1,019 shore crabs among 2,081 styrofoam floaters recorded, resulting in a 49.0% occurrence rate and a density of 42.52 crabs per hectare. The majority (84.2%) of shore crabs occurred during the planting season (February to July). Findings revealed that shore crabs exhibit solitary rafting behavior on styrofoam floaters, maintaining a consistent 1:1 ratio (crab to float). Shore crabs actively dismantle styrofoam floaters, emerging as the primary cause of rapid loss and fragmentation. In contrast to other types of floaters used by seaweed farmers, styrofoam floaters appeared to be attractive to shore crabs for rafting, posing a potential risk of ingestion. Regulating the use of styrofoam floaters in the area is recommended to prevent microplastic contamination, promoting responsible aquaculture and fisheries management. Additionally, flat-surfaced floats that are sturdy and more eco-friendly can be used as alternative floaters and as a basis for redesigning floaters to support the crab's rafting population.
Key Words: Kappaphycus, microplastic, rafting behavior, styrofoam floats, Varuna litterata.
(ProQuest: ... denotes formulae omitted.)
Introduction. The euryhaline crab, Varuna litterata (Fabricius, 1798) belongs to the family Varunidae under the phylum Arthropoda and infraorder Brachyura (WoRMS 2023). They are called grapsid crab, commonly known as the 'herring bow crab' (Devi et al 2013) or paddler crab (Bouchard et al 2013), locally known in the Philippines as "Talangka" in Tagalog dialect, "Katang" and "Calampay" in Ilongo, "Kalampay" in Cebuano (Motoh 1980), "Kalimpay" in Cuyono (Jumawan et al 2022), "Карр!" in Ilocos (Mendoza et al 2023; Rojas 2023), while also called as "Talangka", and sometimes "Kimpi" or "Ulok" in the Bicol region. М. litterata are euryhaline and can be found in rivers, brackishwater, or at sea (Bouchard et al 2013), inhabiting...