Growth rates of five species of subtidal clam on a beach in the South Island, New Zealand

1996 ◽  
Vol 47 (6) ◽  
pp. 773 ◽  
Author(s):  
HJ Cranfield ◽  
KP Michael ◽  
RICC Francis

Growth rates of five species of New Zealand surf clams were estimated at Cloudy Bay, Marlborough, from analyses of sequential length-frequency samples with the computer program MULTIFAN and analyses of incremental growth of marked individuals with the computer program GROTAG. The von Bertalanffy parameters k and L∞ estimated by MULTIFAN were: Paphies donacina, 0.33 and 94.1; Spisula aequilatera, 1.01 and 60.3; Mactra murchisoni, 0.57 and 88; M. discors, 0.41 and 68; data for Dosinia anus could not be analysed reliably. These parameters estimated by GROTAG were: P. donacina, 0.35 and 84.8; S. aequilatera, 1.74 and 57.6; M. murchisoni, 0.58 and 80.6; M. discors, 0.54 and 61.5; D. anus, 0.36 and 61.6. The age-based growth estimated by MULTIFAN is not strictly comparable with the length-based growth estimated by GROTAG, but graphical comparisons show that both programs estimate similar growth rates for each species of surf clam. Interspecies differences in growth rates are hypothesized to be related to differences in species depth distribution within the surf zone. S. aequilatera, with the highest growth rate, is found just inshore of the primary wave break, where surf diatom abundance is postulated to be highest. An extension to the linear growth model of GROTAG that allows the predicted growth of larger animals to decline asymptotically to zero and never be negative is presented.


2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Collette H. Mwanangombe ◽  
Deon Durholtz ◽  
Dawit Yemane ◽  
Jean Githaiga-Mwicigi ◽  
Warwick H. H. Sauer ◽  
...  

Growth of adult chokka squid Loligo reynaudii d’Orbigny was modelled using mantle length and age data derived from samples collected over two years (2003 and 2004) from a single, large cohort of mature and spawning squid. A total of 588 statoliths were examined (310 males, 278 females) from individuals of 71–425 mm mantle length (ML). The maximum size of chokka squid was 425 mm ML for males and 263 mm ML for females. The Francis Growth Model and Linear Growth model were selected for further analysis from six models considered. Males and females attain similar ages, although mantle length-based daily growth rates ranged from 0.75 to 1.02 (0.88 quantile _50) mm/day for males and 0.32–0.45 (0.38 quantile _50) mm/day for females, explaining the sexual dimorphism apparent in the sizes of individuals of this species.



2021 ◽  
Vol 8 ◽  
Author(s):  
Paul Maneval ◽  
Charles A. Jacoby ◽  
Holden E. Harris ◽  
Thomas K. Frazer

Growing fragments of corals in nurseries and outplanting them to supplement declining natural populations have gained significant traction worldwide. In the Caribbean, for example, this approach provides colonies of Acropora cervicornis with minimal impacts to existing wild colonies. Given the impetus to scale up production to augment limited natural recovery, managers and researchers should consider how the design and location of the nurseries affect the growth of different genotypes of corals and the effort required for maintenance. To elucidate such influences, we grew fragments of different genotypes (five varieties) on differing structures (trees and frames) at two depths (6–8 and 16–18 m). The sum of the lengths of all branches or total linear extensions (TLEs) and accumulation of biofouling were measured over 198 days from May to December 2016 to assess the growth of fragments and the effort required to maintain nurseries. TLEs for all fragments increased linearly throughout the incubation period. Mean daily incremental growth rates varied among the genotypes, with one genotype growing significantly faster than all others, two genotypes growing at intermediate rates, and two genotypes growing more slowly. Mean daily incremental growth rates were higher for all genotypes suspended from vertical frames at both sites, and mean daily incremental growth rates were higher for all fragments held on both types of nurseries in deeper water. If linear growth continued, a fragment of the fastest growing genotype held on a frame in deeper water was estimated to increase the sum of the length of all its branches by an average of 88 cm y–1, which was over two times higher than the estimated mean annual growth rate for a fragment of the slowest growing genotype held on a tree in shallow water. Nurseries in deeper water had significantly less biofouling and appeared to be buffered against daily fluctuations in temperature. Overall, the results demonstrated that increased production and reduced maintenance can result from considering the genotype of fragments to be cultured and the design and location of nurseries.



1986 ◽  
Vol 20 (1) ◽  
pp. 121-130
Author(s):  
S. Chatterjee ◽  
C. Michelini


Author(s):  
J. Walker

Abstract A description is provided for Melampsora medusae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Pycnia and aecia on Coniferae, especially Larix and Pseudotsuga, less commonly on Pinus and other genera (Ziller, 1965). Uredinia and telia on species of Populus, especially Populus deltoides, and its varieties and hybrids P. balsamifera, P. nigra var. italica and others. Its exact host range on species of Populus is not known due to confusion with other species of Melampsora and to uncertainty in the reported identity of some species of Populus and clones (Walker, Hartigan & Bertus, 1974). DISEASE: Leaf rust of poplars, causing severe leaf damage and early defoliation on susceptible species and clones. Continued defoliation of successive flushes of growth predisposes trees to winter injury and dieback (Peace, 1962) and can cause death of trees, especially nursery stock and trees 1-2 yr old (25, 204; 47, 241; Walker Haitigan & Bertus, 1974). Reduction in incremental growth of timber occurs with susceptible varieties. Some damage can occur to the conifer hosts. It is often severe on Pseudotsuga menziesii (45, 459; 47, 126) and in nurseries Pinus spp. and Larix spp. can be heavily attacked (Ziller, 1965). GEOGRAPHICAL DISTRIBUTION: North America (Canada, USA), Asia (Japan); Australasia and Oceania (Australia, New Zealand); Europe (France, Spain). Reports of Melampsora spp. on poplars (including P. deltoides and P. canadensis) from South America (Argentina, 21, 173), Uruguay (Lindquist & de Rosengurtt, 1967) may refer in part to M. medusae. TRANSMISSION: By air-borne urediniospores, often over long distances (suspected from eastern Australia to New Zealand). Urediniospores survive the winter in milder climates on semi-evergreen lines and on green sucker growth of deciduous trees. This is probably the main method of overwintering in the Southern Hemisphere and in warmer parts of the Northern Hemisphere. The possibility of bud carryover as occurs with M. epitea on Salix in Iceland (Jorstad, 1951) and the Canadian Arctic (Savile, 1972) should be investigated. Telia survive the winter and basidiospores formed in spring infect susceptible conifers in parts of the Northern Hemisphere (Ziller, 1965) but no conifer infection has so far been found in Australia.



1964 ◽  
Vol 44 (3) ◽  
pp. 315-319
Author(s):  
J. M. Bell

Growth records were obtained from 12 research establishments across Canada for pigs fed according to current (1960–63) recommendations of nutrition and management. Growth curves showing age in days and weight in pounds are presented for the various breeds and crossbreds, for between-station comparisons, for comparison of upper and lower quartiles in purebred pigs, and for comparison of growth rates of purebreds with that of Yorkshires of 20 to 25 years ago.Age at 200 lb averaged from 152 to 187 days, among 10 stations for the Yorkshire breed. Pigs of each of the pure breeds reached 200 lb about 3 weeks earlier than that indicated in previous studies. Crossbred pigs of each of four different crosses grew more rapidly than average Yorkshires, some reaching 200 lb in 140 days and having gains in excess of 2.3 lb/day during the finishing period. Yorkshire, Lacombe, and Landrace pigs had similar growth curves. The upper quartile averaged 1.8 and the lower 1.4 lb/day gain between 100 and 200 lb weights. Slow-maturing pigs tended to be below average throughout life but differences in maturity between stations seemed to reflect differing rates of gain in early life, since finishing period gains were similar in 8 of 10 stations.



2018 ◽  
Vol 67 (2) ◽  
pp. 66-73 ◽  
Author(s):  
KE Lawrence ◽  
BL Lawrence ◽  
RE Hickson ◽  
CA Hewitt ◽  
KR Gedye ◽  
...  


2021 ◽  
Author(s):  
◽  
Guyo Duba Gufu

<p>Biological invasion by non-native plant species has often been cited as a cause of native biodiversity loss. While the outcome of species invasions depends on interactions between exotic and resident native species, most studies of biological invasions have focused solely on the direct negative impacts of non-indigenous species on native biota. Although investigations of the role of competition in shaping natural plant communities were dominant in the previous generations and are still popular, more recent experimental research has uncovered the striking influence of facilitation on community dynamics. This thesis aims to investigate competitive and facilitative influence of the invasive South African iceplant (Carpobrotus edulis) on Spinifex sericeus, a native foredune grass species, with particular reference to implications of these interactions for dune restoration in New Zealand. It further explores the growth rates, substrate preferences and mating systems of the exotic and native iceplant taxa found in New Zealand. I begin by briefly outlining the influence of competition and facilitation on natural plant communities with reference to the role of facilitation in eco-restoration. I also give a few examples where exotic species have been found to facilitate native ones. Secondly, a neighbour removal experiment was conducted on coastal sand dunes with the main aim of studying the effects of Carpobrotus edulis on establishment of Spinifex sericeus at the foredune region. Finally, I compared the growth rates of the most widely distributed iceplant taxa in New Zealand in different substrates and the breeding systems of the exotic Carpobrotus.  Examples abound in literature of exotic plant species facilitating native ones especially in forestry. In the neighbour removal study, Carpobrotus edulis protected Spinifex seedlings against storm erosion, sandblasting and salt sprays while at the same time suppressing its leaf production. Suppression of Spinifex leaf production was more pronounced at top of the dune where stress elements is presumably more benign. There was no evidence of allelopathic suppression of Spinifex by C. edulis. Only Carpobrotus chilensis displayed some level of substrate preference by putting on relatively lower biomass in gravel. The exotic Carpobrotus spp. put on greater dry matter content than the native Disphyma australe and the Carpobrotus-x-Disphyma hybrid. The hybrid displayed a faster vegetative growth rate whereas D. australe allocated relatively more biomass to the roots than the shoot. Both Carpobrotus spp. are self compatible and highly capable of intrageneric and intergeneric hybridisation. Mass removal of the existing exotic iceplant stands from foredunes along high energy coasts is not advisable as they serve as useful stabilisers. The intergeneric hybrid is sexually sterile with sparsely spread stolons that could allow co-occurrence with other species and therefore is more suitable for foredune stabilisation. However, more research needs to be conducted on the ecology of the intergeneric hybrid.</p>



1980 ◽  
Vol 58 (7) ◽  
pp. 1220-1226 ◽  
Author(s):  
L. R. Russell

Growth and swimming abilities of fingerling and 1.5-year-old rainbow trout infected with the nematode parasite Truttaedacnitis truttae were examined. Control trout and trout infected in the laboratory with 5, 10, 20, 40, or 80 worms exhibited similar growth characteristics over a 10-week period within each of four experimental groups fed different rations of trout chow (1, 2, 3, or 4% of wet body weight fed per day). Decreasing growth rates showed some correlation with increasing numbers of nematode parasites. Differences between growth rates, amounts of food consumed, and food conversion efficiencies of infected and noninfected fish were not statistically significant. Critical swimming speed, fixed velocity, and burst velocity stamina tests revealed similar swimming abilities in both control and infected trout. Maximum swimming speeds attained and time to fatigue at cruising speeds were more closely related to fish size than to numbers of worms with which fish were infected. Importance to rainbow trout survival of large natural infections with T. truttae is discussed.



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