THE ABUNDANCE OF HARBOR SEALS IN THE GULF OF ALASKA

The abundance of harbor seals ( Phoca vitulina richardii ) has declined in recent decades at several Alaska locations. The causes of these declines are unknown, but there is concern about the status of the populations, especially in the Gulf of Alaska. To assess the status of harbor seals in the Gulf of Alaska, we conducted aerial surveys of seals on their haul-out sites in August-September 1996. Many factors influence the propensity of seals to haul out, including tides, weather, time of day, and time of year. Because these "covariates" cannot simultaneously be controlled through survey design, we used a regression model to adjust the counts to an estimate of the number of seals that would have been ashore during a hypothetical survey conducted under ideal conditions for hauling out. The regression, a generalized additive model, not only provided an adjustment for the covariates, but also confirmed the nature and shape of the covariate effects on haul-out behavior. The number of seals hauled out was greatest at the beginning of the surveys (mid-August). There was a broad daily peak from about 1100–1400 local solar time. The greatest numbers were hauled out at low tide on terrestrial sites. Tidal state made little difference in the numbers hauled out on glacial ice, where the area available to seals did not fluctuate with the tide. Adjusting the survey counts to the ideal state for each covariate produced an estimate of 30,035 seals, about 1.8 times the total of the unadjusted counts (16,355 seals). To the adjusted count, we applied a correction factor of 1.198 from a separate study of two haul-out sites elsewhere in Alaska, to produce a total abundance estimate of 35,981 (SE 1,833). This estimate accounts both for the effect of covariates on survey counts and for the proportion of seals that remained in the water even under ideal conditions for hauling out.     

TWO TYPES OF BLUE WHALE CALLS RECORDED IN THE GULF OF ALASKA

At one time blue whales were found throughout the Gulf of Alaska, however, none have been sighted there in post-whaling era surveys. To determine if blue whales ( Balaenoptera musculus ) might now occur in the Gulf of Alaska, an array of hydrophones was deployed there in October 1999. Data were retrieved in May 2000 and in June 2001. Spectrograms from a random subsample comprising 15% of the ∼63,000 h of data were visually examined for blue whale calls. Call types attributed to both northeastern and northwestern Pacific blue whales were recorded. Both of these call types were recorded seasonally from the initial deployment date in October 1999 through the third week of December 1999 and then from July 2000 through mid-December 2000. Both call types were regularly recorded on the same hydrophone at the same time indicating clear temporal and spatial overlap of the animals producing these calls. Two blue whale call types were recorded in the Gulf of Alaska suggesting that perhaps two stocks use this area. The northeastern call type has now been documented from the equator up to at least 55°N in the eastern North Pacific.     

Mussel beds in deeper water provide an unusual situation for competitive interactions between the seastars Leptasterias polaris and Asterias vulgaris

The common seastars Leptasterias polaris and Asterias vulgaris show competitive interactions in shallow subtidal communities in the northern Gulf of St. Lawrence, particularly during summer when aggregations of the two seastars forage on mussel beds at 1-2 m in depth. We examined interactions between the two seastars in a different situation, in a mussel bed at 6 m in depth (a rare situation in this region). In the deeper mussel bed, seastars were three times more abundant than in the shallower beds, and the mussels were larger. The deeper bed disappeared rapidly due to the intense predation. Although decreased prey abundance should have favored interference interactions, we did not detect either partitioning of mussels by size or avoidance of A. vulgaris by L. polaris as previously reported when mussels are in short supply in shallower water. The lack of an avoidance behavior by L. polaris, together with the higher proportion of L. polaris than A. vulgaris that were feeding, suggests that in this situation, the dominance of A. vulgaris (observed in shallower water) is attenuated, or that L. polaris may dominate.     

广西龙眼种质资源研究及品种选育

本文概述广西龙眼种质资源的特点,综述广西龙眼种质资源调查、亲缘关系研究和引种、品种选育进展,并提出进一步开展研究利用的建议.     

Analysis of asymmetries in the African fruit bats Eidolon helvum and Rousettus egyptiacus (Mammalia: Megachiroptera) from the islands of the Gulf of Guinea. I. Variance and size components of bilateral variation

A set of cranial characters was examined in the fruit bats Rousettus egyptiacus and Eidolon helvum to compare trends and relative importance of major components of bilateral morphometric variation, and their relationship with character size. Using two‐way, sides‐by‐individuals ANOVA , four components of variation were estimated for each bilateral variable: individual variation (I), directional asymmetry (DA), non‐directional asymmetry (NDA) and measurement error (E). Both species exhibit similar major trends of variation in asymmetry across characters, as shown by principal component analysis, using variance components as variables. Degree of interspecific congruence among characters was confirmed by a two‐way ANOVA with species and variance components as fixed factors. Congruence of asymmetry patterns between species suggests that the concept of population asymmetry parameter (PAP) could be extended to higher hierarchies. PAPs above the species level may result from common mechanisms or similar developmental constraints acting on species’ buffering capacities and morphological integration processes.     

Assessing Stressors in Coastal Ecosystems: An Approach to the Patient

Medicine employs an approach to diagnose, give a prognosis, and develop a treatment for human patients. Specific signs and symptoms determined from medical examinations, laboratory tests, and patient history are utilized to predict the outcome of a potential pathological disorder. Utilizing a strategy similar to the medical examination, the status of ecosystems can be examined. To demonstrate this concept a “patient” case study of the Gulf of Mexico is described. The diagnosis of potential abnormalities within the Gulf of Mexico was conducted by examining field indicators including sediment chemistry and tissue chemistry (field examinations), sediment toxicity (laboratory testing), and a benthic index (patient history and existing symptoms). Based on the diagnosis (ecological assessment), a prognosis for the Gulf of Mexico was determined and specific areas that are impacted by stressors were identified for more detailed assessments. Pensacola Bay was identified as such an area impacted by stressors. The case study example demonstrates that a medical approach of “diagnosis and prognosis” can be utilized as a strategy to help identify stressors, develop a successful treatment plan, and prevent future ecosystem degradation.     

Applications of Satellite Ocean Color Sensors for Monitoring and Predicting Harmful Algal Blooms

The new satellite ocean color sensors offer a means of detecting and monitoring algal blooms in the ocean and coastal zone. Beginning with SeaWiFS (Sea Wide Field-of-view Sensor) in September 1997, these sensors provide coverage every 1 to 2 days with 1-km pixel view at nadir. Atmospheric correction algorithms designed for the coastal zone combined with regional chlorophyll algorithms can provide good and reproducible estimates of chlorophyll, providing the means of monitoring various algal blooms. Harmful algal blooms (HABs) caused by Karenia brevis in the Gulf of Mexico are particularly amenable to remote observation. The Gulf of Mexico has relatively clear water and K. brevis, in bloom conditions, tends to produce a major portion of the phytoplankton biomass. A monitoring program has begun in the Gulf of Mexico that integrates field data from state monitoring programs with satellite imagery, providing an improved capability for the monitoring of K. brevis blooms.     

Conservation of pteridophytes in São Tomé e Príncipe (Gulf of Guinea)

Twenty-two pteridophytes (13 endemic and 9 non-endemic) from São Tomé e Príncipe (Gulf of Guinea) are evaluated as regards their rarity and conservation status. IUCN Red List Categories are assigned to these taxa. Eight taxa are Critically Endangered (CR), eleven taxa are Vulnerable (VU) and three taxa are Endangered (EN). Specific measures to conserve these rare pteridophytes are outlined.     

广西百色和永乐盆地的始新世猪类化石──兼论早期猪类的分类和演化(英文)

描述了广西百色及永乐盆地发现的中始新世最晚期一晚始新世的猪类化石。这批已知最早的猪超科化石,大大丰富了亚洲地区的早期猪类,对了解全球猪类的早期演化有着重要价值。广西的材料被确定为两个新属新种：萨氏始新猪Ｅｏｃｅｎｃｈｏｅｒｕｓ ｓａｖａｇｅｉ和广西华夏猪Ｈｕａｘｉａｃｈｏｅｒｕｓ ｇｕａｎｇｘｉｅｎｓｉｓ,一个新种：粗壮暹罗猪Ｓｉａｍｏｃｈｏｅｒｕｓ　ｖｉｒｉｏｓｕｓ和一个未定属种：Ｔａｙａｓｓｕｉｄａｅ　ｇｅｎ．ｅｔ　ｓｐ．ｉｎｄｅｔ。加上已发表的单尖旅猪Ｏｄｉｏｃｈｏｅｒｕｓ　ｕｎｉｃｏｎｕｓ,百色、永乐盆地共计发现了５种始新世猪类化石。新属Ｅｏｃｅｎｃｈｏｅｒｕｓ虽然臼齿结构简单,与原始的古猪类（ｐａｉａｅｏｃｈｏｅｒｉｄ）接近,但因其Ｍ３具有一个明显的跟座而被归入猪科。早期猪科动物非常原始的臼齿形式证明,猪科动物的起源并不晚于古猪科（Ｐａｌａｅｏｃｈｏｅｒｉｄａｅ）和西科（Ｔａｙａｓｓｕｉｄａｅ）。旧大陆的古猪类长期以来被认为与新大陆的西类（ｔａｙａｓｓｕｉｄ）更为接近,多数学者将其归入西科。笔者认为两者共有的近祖特征,并不能支持它们更近的亲缘关系,而且古猪类缺乏典型西类的近裔特征,因而支持将Ｐａｌａ?     

记广西田东却林缅甸先炭兽的新材料

记述了产自广西田东县却林那读组中一残破的缅甸先炭兽 (Anthracokeryxbirmanicus)头骨。通过对化石的描述 ,对该种特征进行了补充和分析 ,并认为其终生生长的上犬齿可能是用来作为争夺领域和配偶的武器。终生生长的上犬齿的发现 ,证明炭兽类具有性双形。将那读动物群和缅甸邦唐动物群进行对比 ,认为那读组的时代很可能有一部分属于中始新世