Compensatory Growth of the Sandbar Shark in the Western North Atlantic Including the Gulf of Mexico

The number of Sandbar Sharks Carcharhinus plumbeus in the western North Atlantic Ocean has experienced a drastic decline since the early 1980s, reaching a minimum during the early 1990s. Catch rates in the early 1990s were a mere 25% of those during the 1980s. According to several fishery-independent surveys, the low point in Sandbar Shark abundance followed a period of high exploitation. Growth models fit to age-length data collected from 1980 to 1983 and from 2001 to 2004 were compared to investigate potential changes in parameter estimates that might reveal compensatory responses in the Sandbar Shark population. Statistical differences were found between the model parameters for the two time periods, but the differences in growth rates were minimal. The parameters from the three-parameter von Bertalanffy growth model for female sharks during the 1980-1983 and 2000-2004 time periods were as follows: L = 188.4 and 178.3cm FL; k = 0.084 and 0.106; and t(0) = -4.097 and -3.41. For males the growth parameters were as follows: L = 164.63 and 173.66cm; k = 0.11 and 0.11; and t(0) = -3.62 and -3.33. The estimated age at 50% maturity for female Sandbar Sharks changed from 15years to 12.49years between the two time periods

Growth and Demography of the Solitary Scleractinian Coral Leptopsammia pruvoti along a Sea Surface Temperature Gradient in the Mediterranean Sea

The demographic traits of the solitary azooxanthellate scleractinian Leptopsammia pruvoti were determined in six populations on a sea surface temperature (SST) gradient along the western Italian coasts. This is the first investigation of the growth and demography characteristics of an azooxanthellate scleractinian along a natural SST gradient. Growth rate was homogeneous across all populations, which spanned 7 degrees of latitude. Population age structures differed between populations, but none of the considered demographic parameters correlated with SST, indicating possible effects of local environmental conditions. Compared to another Mediterranean solitary scleractinian, Balanophyllia europaea, zooxanthellate and whose growth, demography and calcification have been studied in the same sites, L. pruvoti seems more tolerant to temperature increase. The higher tolerance of L. pruvoti, relative to B. europaea, may rely on the absence of symbionts, and thus the lack of an inhibition of host physiological processes by the heat-stressed zooxanthellae. However, the comparison between the two species must be taken cautiously, due to the likely temperature differences between the two sampling depths. Increasing research effort on determining the effects of temperature on the poorly studied azooxanthellate scleractinians may shed light on the possible species assemblage shifts that are likely to occur during the current century as a consequence of global climatic change

Bayesian hierarchical nonlinear models for estimating coral growth parameters

In ecology, the standard tool for investigating the growth of marine speciesis the von Bertalanffy growth function (VBGF). The parameters of this func-tion are usually estimated by methods that might induce bias in the resultsbecause the VBGF neither distinguishes between the variability at individual orpopulation levels nor takes into account the contribution of site-specific environ-mental factors. A major problem arises when environmental measures are notdirectly linked to data because they are observed at different spatial locations,scales, or times. In this case, the association between site-specific environmentalfeatures and individual data might be forced. A Bayesian hierarchical nonlin-ear model (BHNLM) is proposed to provide reliable estimation of the VBGFparameters while taking into account biological information and site variabil-ity. We illustrate the advantages of the hierarchical structure that allow us tocapture the differences among species and sites when environmental informa-tion is ignored. The proposal is assessed through a case study concerning twoMediterranean corals,Balanophyllia europaeaandLeptopsammia pruvoti,improving both the statistical accuracy and the quantification of uncertaintiesaffecting marine species growth

The Autoling System

The AUTOLING system represents an attempt to replace the human linguist with a machine in the process of linguistic fieldwork with an informant. To the extent that the attempt succeeds, the analytic and heuristic methodology of live linguists can be considered formalized. The current system consists of three as yet unjained components: a morphological analyzer, a program for learning context-free phrase structure grammar, and a program for learning monolingual and bilingual transformations. All programs are written in ALGOL and operational on the Burroughs B-5500 computer. The capabilities of the system are illustrated with examples of its treatment of selected problems in English, Latin, Roglai, Indonesian, Thai, Chinese and German