Assessment and Valuation of Commercially Important Bivalves and Gastropods within the Seagrass Beds of Laguindingan, Misamis Oriental and Rizal, Zamboanga del Norte, Philippines

A study was conducted to assess the abundance and value of commercially important bivalves and gastropods within the seagrass beds of Laguindingan, Misamis Oriental and Rizal, Zamboanga del Norte, Mindanao, Philippines. The line transect method was used to assess the diversity of the bivalves and gastropods within the seagrass beds and coring was used in collecting sediment samples. Laguindingan was categorized as undisturbed site, while Rizal as disturbed site. The results identified three families of gastropods in undisturbed and thirteen families in disturbed, comprising a total of seven bivalves and six gastropods. Cyprea sp. Dominated in undisturbed area, while Anadara inequivalves dominated in disturbed area. The diversity index in disturbed (1.57) was greater than in undisturbed (0.88) probably due to high organic matter (2.56ppm) compared to the undisturbed area (1.92ppm). Ironically, the total volume of bivalves and gastropods production in disturbed area was higher at19.84 kg compared with2.23 kg in undisturbed. In terms of total monetary value, the undisturbed production could yield PHP 22,672.32 (USD 466.48) in an approximated area of 165 ha, while PHP 422,130.50 (USD 8,685.37) in 326 ha in the disturbed area. The study revealed that higher diversity resulted in higher production with greater monetary value derived from bivalves and gastropods in disturbed area contributed by higher organic load. Protection and management of the seagrass beds is likely most needed in both disturbed and undisturbed are as to support not only a robust but also a healthy production of shellfish fit for human consumption.

Notes on the Reproductive Traits of Holothuria fuscogilva Cherbonnier, 1980 from Laguindingan, Misamis Oriental, Philippines

Reproductive traits of white teatfish Holothuria fuscogilva from Laguindingan, Misamis Oriental were investigated from February to July 2020. Gonad samples from 62 adult individuals weighing 1,240g to 5,800g were collected and examined macroscopically and microscopically to determine gonad morphology, sex ratio, gonad maturity, and gonad index. Gonads were composed of numerous branched tubules of varying lengths and frequency of bifurcations arising from the gonad basis. There was no significant variation in the ratio of male to female white teatfish (x2=2.32, α=0.05) and were mostly mature in May (weighing 1,750g–4,000g in males and 2,600g-3,900g in females) with relatively high gonad output. Information on gonad maturation is useful in the development of a successful breeding technology for this economically important sea cucumber species.