Mussel Community Studies [Year Three].

The communities associated with Mytilus californianus (mussel) beds from 20 geographic sites in southern California were examined. The study areas included six mainland sites - Government Point, Goleta Point, Ventura, Corona del Mar, Carlsbad, and San Diego,and two sites on opposite sides of seven offshore islands - San Miguel Island, Santa Rosa Island, Santa Cruz Island, Anacapa Island, San Nicholas Island, Santa Cruz Island and San Clemente Island. : The mussel communities from all areas contributed to the master species list which now encompasses conservatively, 610 species of animals and 141 species of algae. The most diverse collection came from Cat Rock, Anacapa Island where the mussel beds supported 174 species of invertebrates. The lowest diversity was recorded for mussel beds from Ben Weston, Santa Catalina Island which contained 46 species. In general, the island mussel beds supported a greater diversity of both animals and plants. Mussel community samples were collected from upper and lower intertidal areas occupied by the mussel beds within a locality. Community differences in both composition and abundance were associated with these collections. Overall. community similarity analysis revealed five major patterns which corresponded to characteristic species assemblages occupying the mussel beds from the various geographic areas. The patterns included: (1) clusters of localities which display a north-south geographic pattern with respect to the similarity of their respective mussel communities, (2) a separation of selected island and mainland communities because of dissimilarities in their species composition, (3) differences between mussel communities. on opposite sides of the offshore islands, (4) clusters of species whose highest abundances characterize selected localities, (5) species groups ubiquitous to all mussel beds examined. The results of the community analysis further suggest that predictions can be made delineating the probable mussel community inhabitants of areas not sampled. The species distribution patterns observed appear to correspond in part to the influence of currents and water masses which bear planktonic larvae and impinge on selected localities. The most important mussel bed features associated with community differences were quantitative and qualitative differences in the potential microhabitats. Those features associate~ with greater species diversity include the pore base of coarse fraction shell and rock debris, skewness and kurtosis of the sediment grain-size distributions and mussel bed thickness. Those features associated with lower species diversity included the quantity of tar. and rock and shell debris trapped within the mussel bed. (PDF contains 51 pages)

A new synoptic survey of Northern Ireland lakes: sampling from the air

Northern Ireland has approximately 1670 lakes, which cover 4.4% of the land surface. However, most of the water area is accounted for by the large lakes such as Lough Neagh (385 km2) and Lower Lough Erne (109.5 km ). The majority of lakes are less than 100 hectares in area. They tend to be distributed towards the south and west of the Province, where extensive drumlin swarms are rich in small waterbodies. In 1988-1991, 610 of the 708 lakes between one and 100 hectares were sampled by the Northern Ireland Lake Survey. The objective was to assess their conservation status based on their aquatic macrophyte flora, but in addition to extensive plant surveys, the water of each lake was analysed for a range of chemical variables. This article reports on a full-scale survey carried out in early March 2002. The survey was taken with help of two helicopters. The authorise summarise the results of the chemical analysis of the survey.

James's rule and causes and consequences of a latitudinal cline in the demography of John's Snapper (Lutjanus johnii) in coastal waters of Australia

Demographic parameters were derived from sectioned otoliths of John’s Snapper (Lutjanus johnii) from 4 regions across 9° of latitude and 23° of longitude in northern Australia. Latitudinal variation in size and growth rates of this species greatly exceeded longitudinal variation. Populations of John’s Snapper farthest from the equator had the largest body sizes, in line with James’s rule, and the fastest growth rates, contrary to the temperature-size rule for ectotherms. A maximum age of 28.6 years, nearly 3 times previous estimates, was recorded and the largest individual was 990 mm in fork length. Females grew to a larger mean asymptotic fork length (L∞) than did males, a finding consistent with functional gonochorism. Otolith weight at age and gonad weight at length followed the same latitudinal trends seen in length at age. Length at maturity was ~72–87% of L∞ and varied by ~23% across the full latitudinal gradient, but age at first maturity was consistently in the range of 6–10 years, indicating that basic growth trajectories were similar across vastly different environments. We discuss both the need for complementary reproductive data in age-based studies and the insights gained from experiments where the concept of oxygen- and capacity-limited thermal tolerance is applied to explain the mechanistic causes of James’s rule in tropical fish species.

Feasibility of bi-culture of mud crab (Scylla serrata) and shrimp (Penaeus monodon)

A study on the feasibility of bi-culture of mud crab (Scylla serrata) and shrimp (Penaeus monodon) in brackishwater earthen ponds (0.1 ha each) was carried out for a period of five months (March-August). Nursed shrimp juvenile (ABL:· 3.36±0.23 em and ABW: 0.26±0.04 g) and crab juvenile (ACL: 2.61±0.22 cm, ACW: 4.63±0.11 cm and ABW: 43±2.64 g) were stocked following the experimental design of shrimp 2/m2 (Treatment-1), shrimp 2/m2 and mud crab l/m2 (Treatment-2) and shrimp 2/m2 and mud crab 0.5/m2 (Treatment-3). Crabs were fed with chopped trash tilapia @ 10~5%, while shrimp were fed with Saudi-Bangla shrimp feed @ 3~5% of biomass twice daily. Significantly (p<0.05) higher specific growth rate (SGR) of shrimp and mud crab was 1.86% (g/day) in T2 and 0.83% (g/day) in T3, respectively. The survival of shrimp and mud crab also varied significantly (p<0.05) with a higher mean value of74.63% in Tl and 51.04% in T3, respectively. The production of shrimp (424.09 kg/ha) was significantly (p<0.05) higher in Tl and that of mud crab (568.80 kg/ha) in T2. Significantly (p<0.05) highest total production of 871.29 kg!ha was in T2 followed by 708.52 kg/ha in T3 and 424.09 kg/ha in Tl. The results indicate that mud crab can be cultured at a stocking rate of 1/m2 together with shrimp at 2/m2 •

Substitution of live feed by formulated diet: effect on the growth and survival of Betta splendens (Regan) fry

The present work evaluates the effectiveness of partial or total replacement of live feed (LF) (Tubifex) together with formulated diet (FD) for Betta splendens. Three hundred Betta splendens fry of uniform size (mean weight 0.19±0.01g) were equally distributed in five treatment groups with three replicates in glass aquaria of 351itre capacity. Fishes were given diets at different ratio of LF and FD viz. T1(C) 100% LF; T2 75% LF, 25% FD; T3 50% LF, 50% FD; T4 25% LF, 75% FD and T5 100% FD and the experiment continued for 105 days. T2 group registered highest (P<0.05) % body weight gain (125.61±0.26) and specific growth rate (2.34±0.02), which was similar to T1 and T3 groups. Lowest FCR was recorded in T2 (2.40±0.11) group, which was similar to Tl, T3 and T4 groups. Highest (P<0.05) PER was observed in T4 (1.00±0.03) group, which was similar to T3 and T5 groups. At the end of experiment, highest % survival was recoded in T1, T2 and T3 groups (96.67±1.67), which was similar to T4 group. From the study, it is concluded that LF can be successfully replaced up to 75% by FD without any adverse effect on the growth and survival of Betta splendens.

Ecology of Indian estuaries-XI. A preliminary survey of the fishery resources of the Ashtamudi estuarine system

The fish fauna of the Ashtamudi, the second largest estuarine system in Kerala (8°53'-9°02' N Lat. and 76°31'-76°41' E Long.) is listed. 97 species belonging to 39 families have been recorded, ofwhich69 are commercially important contributing to the fisheries of the Ashtamudi Estuary. Mullets, cichlids and the glassy perchlets are the most abundant groups and contribute appreciably to the landings. Results revealed that the estuarine system supports a good capture fishery which is seasonal. Majority of the fish fauna in the estuary are marine elements recruited from the adjoining Arabian Sea. An inventory of the craft and gear employed is presented and the sources of pollution in the estuarine system are described, aquacultural prospects of this area are discussed.

Study morphologic, phylogenic relationships DNA barcoding of of identified decapod group (Crustacean) of Persian Gulf and Oman Sea.

Phylogenetic relationships among all described species (total of 12 taxa) of the decapoda, were examined with nucleotide sequence data from portions of mitochondrial gene and cytochrome oxidase subunit I (COI). The previous works on phylogeny proved that the mitochondrial COI gene in crustacean is a good discriminative marker at both inter- and intra-specific levels. We provide COI barcode sequences of commertial decapoda of Oman Sea, Persian Gulf, Iran. Industrial activities, ecologic considerations, and goals of the decapoda Barcode of Life campaign make it crucial that species of the south costal be identified. The reconstruction of evolut phylogeny of these species are crucial for revealing stock identity that can be used for the management of fisheries industries in Iran. Mitochondrial DNA sequences were used to reconstruct the phylogeny of the Penaeus species of marine shrimp. For this purpose, DNA was extracted using phenol- chloroform well as CTAB method. The evolutionary relationships among 12 species of the decapoda were examined using 610 bp of mitochondrial (mt) DNA from the cytochrome oxidase subunit I gene. Finally the cladograms were compared and the resulted phylogenetic trees confirmed that the Iran's species origin is Indo-west pacific species. Iran's species, which were not grouped with the other decapoda taxa seem to always form a sister clade with Indo-west pacific species with strong bootstrap support 100%. The result completely agrees with the previously defined species using morphological characters.However, we still lack any comprehensive and clear understanding of phylogenetic relationships in this group.