Temporal stability of gene frequencies within genetically heterogeneous populations of the queen scallop Aequipecten (Chlamys) opercularis

The widely held assumption that gene frequencies within samples of multi-aged organisms are temporally stable has rarely been tested. In order to test this assumption in the commercially exploited bivalve scallop Aequipecten (Chlamys) opercularis (L.), 12 populations were sampled from around the UK over the period 1988–1990 and each was assayed at four putative polymorphic enzyme loci. Most populations were comprised of 3 to 4 year-classes, distinguishable by annual rings laid down on the shell. Three alleles from each locus were used as discriminant-function variables. Discriminant-function analysis based on allele frequencies averaged for each inividual year-class (45 demes) revealed highly significant inter-site heterogeneity. A posteriori classification of individual year-classes based on the discriminant analysis resulted in assignment of year-classes to the correct home site in 80% of cases. If allozyme neutrality is assumed, the phenomenon of predominant local allele frequency-stability through time within populations which are genetically heterogeneous from one site to another raises the possibility that queen scallop populations may be self-recruiting. Despite a planktonic larval phase lasting up to several weeks, this possibility is not excluded by the available hydrographic data.     

Growth,production and biomass of the burrowing protobranch mollusc Yoldia limatula in the Bideford River,Prince Edward Island,Canada

Samples of the population of Yoldia limatula Say were obtained from the Bideford River, Malpeque Bay, Prince Edward Island, Canada, during the summers of 1979 and 1980 by means of a dredge and a Ponar grab sampler. Size frequency analysis demonstrated that individuals in the size range 25- to 35-mm shell length were numerically dominant in May, June and July. Recruitment of juveniles in August resulted in the dominance of individuals of 5 mm and smaller which comprised 50% of the population at that time. The overall sex ratio was 48.8% males to 51.2% females. From annual lengths measured at successive winter growth bands it was determined that one-yr olds attained a shell length of between 13.8 and 17.7 mm, two-yr olds between 26.7 and 28.0 mm, three-yr olds between 33.8 and 35.2 mm, and foru-yr olds had a mean length of 38.7 mm. Y. limatula produced a croppable annual yield of between 1.19 and 2.65 g dry tissue weight m^-2 with P/B ratios of 0.65 and 1.45 respectively.     

Extension rate: A primary control on the isotopic composition of West Indian (Jamaican) scleractinian reef coral skeletons

Large variations in skeletal microarchitecture, and in the carbon and oxygen isotopic composition of the skeleton, exist within single calices and over the surfaces of single colonies of various species of West Indian (Jamaican) scleractinian reef corals. Rapidly extending parts of individual colonies are depleted in both C¹³ and O¹⁸ regardless of the abundance of zooxanthellae in the overlying tissues. We suggest that this relationship is due to active translocation of organic compounds to sites of rapid calcification. Considerable variation in isotopic composition is found in skeletons of different specimens of the same species even when the skeletons are sampled in a consistent manner, come from the same locality and depth, and have a comparable growth history. The isotopic composition of the scleractinian skeleton is vastly more complex than has heretofore been realized.     

Some observations of factors affecting embryonic and larval growth of Pollicipes polymerus (Cirripedia: Lepadomorpha) in vitro

Observations on the effects of several environmental conditions in embryonic and larval cultures are reported for the gooseneck barnacle Pollicipes polymerus (Sowerby, 1833). When the growth rates of control embryos kept in finger bowls at ambient-temperature sea water (ca. 12°–15°C) were compared to those of embryos grown under variously modified circumstances, it was found that growth rates were faster under conditions closely simulating the adult barnacle mantle-cavity (e.g. darkness and aeration). Addition of antimicrobial drugs and reduction of egg-mass size also promoted fast growth and development. Nauplii were fed several species of algae; only three species promoted growth to Stage V or older. Naupliar growth was fastest in larvae fed the combination of Prorocentrum micans/Platymonas sp. Larvae fed Prococentrum micans/pennate diatom grew slowest, and most larvae died at Naupliar Stage III. Interactions between algal species may have affected their nutritional value for Pollicipes polymerus nauplii. Less larval activity, slower growth rates, and higher mortality rates were observed in individuals given small amounts of food. The development of embryos and larvae in culture depends greatly on the culture conditions. These conditions should be described if comparison of timetables and envents are to be made between studies.     

Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTI_SD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTI_SD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTI_SD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming.     

An experimental soft-release of oil-spill rehabilitated American coots (Fulica americana): I. Lingering effects on survival, condition and behavior

In spring 1995, we studied survival, condition and behavior of 37 oiled/rehabilitated (OR) American coots (Fulica americana) (RHB) and compared them to 38 wild-caught, non-oiled and non-rehabilitated coots (REF). All coots were wing-clipped to prevent long-range dispersal, mixed equally and randomly and soft-released into two fenced marshes. Twenty RHB+20 REF coots were subjected to handling and sampling four times during the 4-month study and the remainder were left undisturbed. The study ended before any coots dispersed following remige regrowth. Overall survival was significantly lower for RHB coots, regardless of the way survival was viewed (four Chi 2 tests varied between p<0.045 and p<0.006). Mortality was 2.1 times higher in RHB coots: 51% mortality in RHB coots and 24% in REF coots (4 months total). RHB coots began the experiment 9% lighter in mean body condition indices (BCI=a standardization that corrected for different-sized birds) than REF coots, but REF coots also needed a period of adjustment to captivity. BCIs then varied (p<0.02) similarly among both groups throughout the experiment. Initially, RHB coots lost more weight in comparison to REF coots (although RHB coots fed more), but those RHB coots that did survive recovered to REF-comparable BCIs after about 6 weeks: both higher and equivalent at the beginning of moult and then both equivalent but lower through the moulting period. Long-term RHB coot and REF coot survivors both had significant (p<0.001) positive correlations between their initial and ending body weights. A similar relationship was also suggested for the non-surviving REF coots, but could not be tested for statistical significance. In contrast to all other groups, however, non-surviving RHB coots failed to show any relationship between their initial and ending body weights (p>0.10), indicating that non-surviving RHB coots were unable to gain or maintain body condition for about 2-3 months following their oiling/rehabilitation experience. Throughout the experiment, RHB coots preened more on water and on land, bathed more, slept less during the day, and exhibited feeding and drinking behaviors more frequently or of greater duration than REF coots (all statistical tests with Bonferroni-corrected p<0.05).     

Characterization of emissions of dioxins and furans from ethylene dichloride, vinyl chloride monomer and polyvinyl chloride facilities in the United States. Consolidated report

This is the consolidated report of emissions of PCDD/F from facilities in the organic chemical manufacturing chain leading to polyvinyl chloride. Data have been gathered from facilities in the US and Canada from a number of manufacturers and at various steps in the manufacturing process. Estimates of US emissions or transfers of PCDD/F were generated on an "Upper Bound" and "Most Likely" basis. The Most Likely estimate of US emissions of PCDD/F to the open environment, that is, air, water and land surface by facilities in this chain, based on evaluation of non-detects at one-half the detection limit is about 12 g I-TEQ per year. On this same basis, an estimated 19 g is disposed of in secure landfills.     

Mercury levels in the plumage of red-billed gulls Larus novaehollandiae scopulinus of known sex and age

Samples of 4-8 small body feathers were taken from 27 chicks and 35 adult red-billed gulls caught at their nests on the Kaikoura Peninsula, New Zealand, in December 1988. The adults had been ringed as chicks and were of known ages from 2 to 15 years old. Analysis of total mercury in the feather samples showed that levels were independent of sex and age in adults. Mean fresh weight concentration in adult body feathers was 2.4 microg g(-1). The lack of age accumulation of mercury in gull feathers contrasts with the well known age related accumulation of mercury in tissues of fish and marine mammals, but agrees with predictions of recent studies on mercury dynamics in birds. Mercury levels in chick feathers were about 80% of levels in adult feathers.