The injluence of chronic exposure to W -B and UV-A radiation on growth and photosynthesis of two polar marine diatoms (Pseudonitzschia seriata and Nitzschia sp.) was investigated in cultures exposed to moderate p h e ton jluences for 3-7 days. Population growth rates were diminished 50 % by W-B. Fluorescence induction kinetics of photosystem 11 ( P S I . revealed that W -B caused lower F,/F,,, ratios and halfrise times, indicating damage to the reaction center of PSII and to related elements of the photosynthetic electron transport chain. Carbon assimilation rates per cell and per chlorophyll a were nonetheless highest for UV-B-exposed populations, which also had the highest chlorophyll a content per cell. The W-B-exposed cells were, however, more vulnerable to visible light-induced photoinhibition. Exposure to W -A in the absence of W -B had little eflect on growth, jluorescence induction of P S I , or chlorophyll a contents but did have some inhibitoly e f f t s on carbon assimilation per chlwophyll a and per cell. The increased photosynthetic capacity of W-B-exposed cells suggested some ability to compensate for damage to the photosynthetic apparatus.

Sailfin catfish indigenous to South America are very popular ornamental fish, having previously been introduced to many regions outside their native range. Two species, namely Pterygoplichthys disjunctivus and P. pardalis, are illegal but widespread in Indonesia. They have formed self-sustaining populations, exploited for feeding of domestic animals and locally for human consumption. Also possible hybrids of the two mentioned species were recorded. The surveyed populations were considered established which perfectly fits with the climate matching analysis. Further monitoring and inspection of regions highlighted to be suitable for sailfin catfish is recommended.

No abstract

Moina sp. merupakan salah satu kelompok zooplanktonyang dimanfaatkan sebagai pakan alami untuk larva pada unit pembenihan ikan. Nilai nutrisi pakan alami dapat ditingkatkan untuk memacu pertumbuhan dan kelangsungan hidup larvanikan. Salah satu metode untuk meningkatkan kualitas nutrisi pakan alami Moina sp. adalah melalui pengkayaan dengan minyak jagung, pengkayaan ini dapat meningkatkan kandungan asam lemak pada Moina sp. Penelitian bertujuan untuk mengetahui pertumbuhan dan kelangsungan hidup larva ikan nila yang diberi Moina sp. yang diperkaya dengan minyak jagung. Larva berumur 5 hari pasca menetas (bobot awal 0,09-0,13 g) diberi pakan Moina sp. tigakali sehari secara ad libitum selama 14 hari pemeliharaan. Penelitian didesain dengan Rancangan Acak Lengkap (RAL). Penelitian mengaplikasikan lima perlakuan dosis minyak jagung pada media pengkayaan Moina sp., masing-masing dengan 4 ulangan. Perlakuan tersebut yaitu: A (0 mL/L), B (0,005 mL/L), C (0,010 mL/L), D (0,015 mL/L), dan E (0,020 mL/L). Hasil penelitian menunjukkan bahwa pengkayaan minyak jagung pada Moinasp. dapat meningkatkan pertumbuhan dan kelangsungan hidup larva ikan nila. Kecenderungan pertumbuhan bobot terjadi pada setiap peningkatan dosis pengkayaan. Pertumbuhan bobot mutlak dan kelangsungan hidup tertinggi (masing-masing 20 g dan 78%) terdapat pada pemberian minyak jagung 0,020 mL/L, sedangkan pertumbuhan dan kelangsungan hidupterendah (masing-masing 0,05 g dan 50%) ditemukan pada perlakuan tanpa pengkayaan minyak jagung.