Fish Larvae

Satisfying nutrient requirement of corals is still a major constraint for maintaining corals in marine aquariums. Corals are polytrophic in nature. Heterotrophic feeding on zooplankton is one of the corals’ strategies to overcome nutrient deficiency. Artemia salina nauplii are commonly used as biocarriers for many fish larvae in aquaculture and can also serve as a biocarrier for coral in aquariums, provided coral acceptability, optimal feeding rate, and digestibility of the nauplii are well understood. Feeding rate and digestibility of coral fed on A. salina nauplii at 100, 2,000, 4,000, 6,000, and 10,000 ind. l−1 under light and dark conditions was assessed in this study. The maximum feeding rates of Galaxea fascicularis under light and dark conditions was 113.6 ind. polyp−1 h−1 and 76.9 ind. polyp−1 h−1, respectively. The daily feeding rates of G. fascicularis varies and depends on nauplii density. Light plays an important role in coral feeding. Nevertheless, the quantity of A. salina nauplii consumed by the coral under light and dark conditions was not significantly different (P > 0.05). A. salina nauplii are well accepted by G. fascicularis. Complete nauplii digestion was observed after 180 min. Digestibility of A. salina nauplii by G. fascicularis was positively correlated with digestion time.

Our objective was to determine which survival skills were most informative of larval fish's escape potential, and thereby better understand larval fish strategies for predator evasion and the nature of selective pressures during early life. We examined evasive performance of red drum larvae, Sciaenops ocellatus, in predation trials and related their escape potential to 12 putative survival skills measured in nonlethal assays. The putative survival skills measured were spontaneous swimming speed and the responsiveness, timing and magnitude of escape responses elicited by artificial stimuli. Responsiveness to the predator was the primary determinant of success in predation trials, accounting for 86% of the variation in escape potential. Of 12 putative survival skills and composite variables that summarized all putative skills, only visual responsiveness (proportion of stimulus presentations responded to) was significantly correlated with escape potential. Regression tree analysis showed that three putative survival skills could be applied in sequence to coarsely filter larvae according to escape potential. Previous work showed that batches of larvae (spawns) could be grouped into clusters whose members showed similar levels of performance in most putative skills. Predation trials showed that escape potential varied as predicted by these clusters. Our results imply that some putative survival skills measured in nonlethal assays reflect responsiveness to an actual predator, but they do not relate directly to their analogues in actual predator–prey interactions. Nevertheless, the ability to distinguish unlikely survivors from more fit individuals, even coarsely, can be valuable for designing experiments, and careful interpretation of putative survival skills can improve ecological models designed to project the fate of larval cohorts.

Zooplankton is the source of life for most of aquatic organisms especially in their larval stages. Its importance come from that most fishes depend on it as a source of life after absorbance of the yolk sac. Moreover, the greatest aquatic creatures like many species of whales are filter feeders where the planktonic organisms form the main bulk of their food. The importance of zooplankton as a main source of nutrition of marine fish larvae has been long professed. Many scientists attributed the ability of a fish population to outdistance through the larval period without vast mortality as one of the primary factors determining the size of the resulting year class and hypothesized that competition for food during the larval time might be a major factor affecting survival and subsequent year class strength.

The rotifer Brachionusplicatilis (OF Muller) can be mass cultivated in large quantities and is an important live feed in aquaculture. This rotifer is commonly offered to larvae during the first 7-30 days of exogenous feeding. Variation in prey density affects larval fish feeding rates, ...

The Gulf of California has one of the most diverse ichthyofauna in the region of the Eastern Pacific. Between 850 to 900 species have been described within its different environments. The Gulf of California also shows an endemism of almost 10% of the total number of species. For this reason the Gulf of California has been considered as a biogeographic province apart from the Mexican Province, which is located to the south. It is also a key region from the biogeographic point of view in order to understand the processes and causes of fish distribution.

KOMPOSISI DAN DISTRIBUSI LARVA PELAGIS IKAN DI PERAIRAN TELUK SEMARANG

Musta’in Adinugroho1, Subiyanto1, Haeruddin1

Dipublikasikan pada Seminar Nasional Perikanan dan Kelautan V, Universitas Brawijaya, 2015

Abstrak

Semarang bay is a bay that stretches from Kendal to Demak. This bay has some vital habitats such as estuaries and mangroves that very importance for nursery ground of aquatic organisms such as fish larvae. Fish larvae is dependent by the environment, especially their movement and migration. However human factors such as industrial activities, harbours, residential area, farms and ponds disembogue in this bay. Sampling was conducted between September and October 2014 at 15 stations. Sampling was carried out every two weeks using bongo net (mesh size of 0.2 mm) which was drawn by boat with average speeds of 0.5 m/s for 10 minutes. Identification of fish larvae carried out in Environmental dan Fisheries Resources Management Laboratory, Diponegoro University. 5890 fish larvaes from 22 family were caught and were dominated by Lactarius (36.01%), Stoleporus (28.30%), Atherinomorus (9.80%), Engraulis (7.22%) and Mugil (4.96 %). A small number of fish larvae caught (below 1%) were identified as Gobiopterus, Paramoncanthus, Tylosurus, Leiognathus, Strongylura and Dinematichthyini. Lactarius, Atherinomorus, Stolephorus, Engraulis and Mugil were found in almost every stations. An abundance of fish larvae was found in station E1, C1, D1 and A1,  stations that were close to estuaries and mangrove vegetation. The type and number of fish larvae was quite varied, this is related to the migration of fish and having appropriate environmental conditions for growth. The existence of fish larvae are also influenced by the currents that distribute them. PCA analysis results indicate that the total variance explained was 63.56% with an abundance of fish larvae being related to depth, salinity, abundance of zooplankton and phytoplankton and current speed.

Keywords: pelagic fish larvae, composition, distribution, bay

First-feeding diets employed in the rearing of meagre (Argyrosomus regius) larvae are based on live preys that are commonly enriched to compensate for their deficiency of essential fatty acids. A feeding trial was conducted on meagre larvae (Argyroso-mus regius) fed rotifer (Brachionus plicatilis) and Artemia salina enriched in lipids from an emulsion of cod liver oil (CLO) and a commercial product (CP). The effect of both enrichment products was evaluated on the survival rate, size and lipid composition of meagre larvae. The results showed that larvae fed CLO presented significant higher values of survival rate (35.0 AE 3.2%) and larval size (12.06 AE 1.17 mm) at the end of the experiment, compared to the CP diet (26.0 AE 2.5%, 11.41 AE 0.91 mm, respectively). Both zootechnical parameters were related to the content of polyunsaturated fatty acids in the larvae. Indeed, the larvae fed CLO pre

While qualitative observations of jellyfish intraguild predation abound in the literature, there are only few rate measurements of these interactions. We quantified predation rates among two common jellyfish in northern boreal waters, Cyanea capillata and its prey Aurelia aurita, both of which also feed on crustacean zooplankton and fish larvae. A series of incubation experiments using a wide range of prey concentrations (0.38–3.8 m−3) in large containers (2.6 m3) was carried out. By replenishing the prey continuously as they were captured we maintained a nearly constant prey concentrations. Ingestion rates increased linearly up to prey concentrations of 1.92 m−3, yielding maximum clearance rates of ∼2.37 ± 0.39 m3 predator−1 h−1 for C. capillata predators 16 ± 2.3 cm in diameter. Mean ingestion rate at saturated prey concentrations (1.92–3.85 m−3) was 4.01 ± 0.78 prey predator−1 h−1. Behavioral observations suggested that predators did not alter their swimming behavior during meals, and thus that feeding rates were generally handling limited rather than encounter limited. Predators captured more prey than needed, and semi-digested prey was often discarded when fresh prey was encountered.