Disentangling the impacts of heat wave magnitude, duration and timing on the structure and diversity of sessile marine assemblages

Extreme climatic events, including heat waves (HWs) and severe storms, influence the structure of marine and terrestrial ecosystems. Despite growing consensus that anthropogenic climate change will increase the frequency, duration and magnitude of extreme events, current understanding of their impact on communities and ecosystems is limited. Here, we used sessile invertebrates on settlement panels as model assemblages to examine the influence of HW magnitude, duration and timing on marine biodiversity patterns. Settlement panels were deployed in a marina in southwest UK for ≥5 weeks, to allow sufficient time for colonisation and development of sessile fauna, before being subjected to simulated HWs in a mesocosm facility. Replicate panel assemblages were held at ambient sea temperature (∼17 °C), or +3 °C or +5 °C for a period of 1 or 2 weeks, before being returned to the marina for a recovery phase of 2–3 weeks. The 10-week experiment was repeated 3 times, staggered throughout summer, to examine the influence of HW timing on community impacts. Contrary to our expectations, the warming events had no clear, consistent impacts on the abundance of species or the structure of sessile assemblages. With the exception of 1 high-magnitude long-duration HW event, warming did not alter not assemblage structure, favour non-native species, nor lead to changes in richness, abundance or biomass of sessile faunal assemblages. The observed lack of effect may have been caused by a combination of (1) the use of relatively low magnitude, realistic heat wave treatments compared to previous studies (2), the greater resilience of mature adult sessile fauna compared to recruits and juveniles, and (3) the high thermal tolerance of the model organisms (i.e., temperate fouling species, principally bryozoans and ascidians). Our study demonstrates the importance of using realistic treatments when manipulating climate change variables, and also suggests that biogeographical context may influence community-level responses to short-term warming events, which are predicted to increase in severity in the future.

Patterns of faunal change at an upper Cambrian trilobite extinction event, Nolichucky Formation, Tennessee and Virginia

During the Upper Cambrian there were three mass extinctions, each of which eliminated at least half of the trilobite families living in North American shelf seas. The Nolichucky Formation preserves the record of one of these extinction events at the base of the Steptoean Stage. Sixty-six trilobite collections were made from five sections In Tennessee and Virginia. The lower Steptoean faunas are assigned to one low diversity, Aphelaspis-dominated biofacies, which can be recognized in several other parts of North America. In Tennessee, the underlying upper Marjuman strata contain two higher diversity biofacies, the Coosella-Glaphyraspis Biofacies and the Tricrepicephalus-Norwoodiid Biofacies. At least four different biofacies are present in other parts of North America: the Crepicephalus -Lonchocephalus Biofacies, the Kingstonia Biofacies, the Cedaria Biofacies, and the Uncaspis Biofacies. A new, species-based zonation for the Nolichucky Formation imcludes five zones, three of which are new. These zones are the Crepicephalus Zone, the Coosella perplexa Zone, the Aphelaspis buttsi Zone, the A. walcotti Zone and the A. tarda Zone. The Nolichucky Formation was deposited within a shallow shelf basin and consists largely of subtidal shales with stormgenerated carbonate interbeds. A relative deepening is recorded In the Nolichucky Formation near the extinction, and is indicated In some sections by the appearance of shale-rich, distal storm deposits above a carbonate-rich, more proximal storm deposit sequence. A comparable deepening-upward sequence occurs near the extinction in the Great Basin of southwestern United States and in central Texas, and this suggests a possible eustatic control. In other parts of North America, the extinction IS recorded In a variety of environmental settings that range from near-shore to slope. In shelf environments, there is a marked decrease in diversity, and a sharp reduction in biofacies differentiation. Although extinctions do take place in slope environments, there IS no net reduction in diversity because of the immigration of several new taxa.

Faunal analysis of the species Anastrepha in the fruit growing complex Gaviao River, Bahia, Brazil

Besides being considered the greatest pests of fruit growing, fruit flies constitute a large obstacle to the growth of the exportation of fresh fruit. Knowledge of the structure of fruit fly communities is of great importance to the bioecological studies of these insects, but there is a lack of information about the faunistic composition of fruit flies in Brazil. The objective of this work was to analysis the composition of the species of Anastrepha, in eleven mango orchards of the fruit growing complex Gaviao River, Bahia, Brazil. These studies were done in 2004 and 2005, in Anage, Caraibas and Belo Campo town, 23 McPhail traps, which collected 798 female fruit flies from the genus Anastrepha. The structure of these communities was evaluated in each orchard by means of faunistic indexes frequency, constancy, dominance, diversity and similarity. The number of species varied from four to eight in each orchard; and the following species was recorded: Anastrepha fraterculus (Wiedemann), Anastrepha obliqua (Macquart), Anastrepha dissimilis Stone, Anastrepha amita Zucchi, Anastrepha distincta Greene, Anastrepha pickeli Lima. Anastrepha sororcula Zucchi and Anastrepha zenildae Zucchi. The most frequent and dominant species were A. fraterculus and A. obliqua. The indexes of diversity varied from 1.01 to 1.62. In general, the similarity between orchards was high (above 55.0%). We observed the formation of groups, one constituted by Frutvale, Carlan, Santa Clara and Panorama orchards; another composed of Cofet, Campo Gaviao and Ouro Verde and a third group formed by Boa Vista orchard. Barra da Onca and Arruda are distinguished from other orchards.

Diversity of Ephemeroptera (Insecta) of the Serra da Mantiqueira and Serra do Mar, southeastern Brazil

Diversity of Ephemeroptera (Insecta) of the Serra da Mantiqueira and Serra do Mar, southeastern Brazil. The aim of this study was to inventory the mayfly fauna, based on nymphal and alate stages, in Serra da Mantiqueira and in Serra do Mar, Sao Paulo State, as well as to present information about habitats used by the genera. Nymphs were collected in several streams and mesohabitats with a Surber sampler and the winged stages with light attraction methods, entomological nets, and Malaise traps. In all, eight families and 33 genera were recorded, representing a very significant portion of the Brazilian fauna (80% of families and 49% of genera). Furthermore, it was possible to identify 11 species, of which two are new records for the state: Tricorythodes santarita Traver and Caenis reissi Malzacher. Despite the high diversity recorded, the accumulation curves presented an ascending form, indicating an increase in the number of genera with additional sampling effort. The high richness found in these areas are in agreement with the high biodiversity of the Atlantic Forest biome and the sampling effort employed, which included the use of different methods, the collection of both nymphs and winged stages, and the sampling of a large area with diverse streams and habitats.

Radiolarian faunal turnover across the Oligocene/Miocene boundary in the equatorial Pacific Ocean

The global warming trend of the latest Oligocene was interrupted by several cooling events associated with Antarctic glaciations. These cooling events affected surface water productivity and plankton assemblages. Well-preserved radiolarians were obtained from upper Oligocene to lower Miocene sediments at Ocean Drilling Program (ODP) Leg 199 Sites 1218 and 1219 in the equatorial Pacific, and 110 radiolarian species were identified. Four episodes of significant radiolarian faunal changes were identified: middle late Oligocene (27.5 to 27.3 Ma), latest Oligocene (24.4 Ma), earliest Miocene (23.3 Ma), and middle early Miocene (21.6 Ma). These four episodes approximately coincide with increases and decreases of biogenic silica accumulation rates and increases in delta18O values coded as "Oi" and "Mi" events. These data indicate that Antarctic glaciations were associated with change of siliceous sedimentation patterns and faunal changes in the equatorial Pacific. Radiolarian fauna was divided into three assemblages based on variations in radiolarian productivity, species richness and the composition of dominant species: a late Oligocene assemblage (27.6 to 24.4 Ma), a transitional assemblage (24.4 to 23.3 Ma) and an early Miocene assemblage (23.3 to 21.2 Ma). The late Oligocene assemblage is characterized by relatively high productivity, low species richness and four dominant species of Tholospyris anthophora, Stichocorys subligata, Lophocyrtis nomas and Lithelius spp. The transitional assemblage represents relatively low values of productivity and species richness, and consists of three dominant species of T. anthophora, S. subligata and L. nomas. The characteristics of the early Miocene assemblage are relatively low productivity, but high species richness. The two dominant species present in this assemblage are T. anthophora and Cyrtocapsella tetrapera. The most significant faunal turnover of radiolarians is marked at the boundary between the transitional/early Miocene assemblages.

Radiolaria abundance and faunal indices of ODP Hole 183-1138A, Kerguelen Plateau

Three sites from Ocean Drilling Program (ODP) Leg 183 (Kerguelen Plateau) have been analyzed to document faunal change in high-latitude radiolarians and to compare the faunal change to Eocene-Oligocene climatic deterioration. Radiolarians are not preserved in Eocene sediments. In Oligocene sediments, radiolarian preservation improves in a stepwise manner toward the Miocene. A total of 115 species were found in lower Oligocene samples from Site 1138; all are documented herein. Radiolarian preservation is presumably linked to productivity triggered by climatic cooling during the early Oligocene. Similar patterns of improving preservation through the Eocene/Oligocene boundary are documented from several Deep Sea Drilling Project and ODP sites in the Southern Ocean, indicating a general pattern. In contrast to the Southern Kerguelen Plateau, however, proxies for productivity are more divergent at Site 1138 (Central Kerguelen Plateau). Whereas carbonate dissolution, as indicated by poor preservation of foraminifers and common hiatuses, is very pronounced in the upper Eocene-lowermost Oligocene, the quality of radiolarian and diatom preservation does not significantly increase until the uppermost lower Oligocene. Multiple measures of radiolarian diversity in the Oligocene from Site 1138 closely parallel radiolarian preservation, indicating that preserved radiolarian diversity is controlled by productivity.

Faunal turnovers in the central Pacific benthic foraminifera during the Paleocene-Eocene thermal maximum

Although it is well known that the Paleocene/Eocene thermal maximum (PETM) coincided with a major benthic foraminiferal extinction event, the detailed pattern of the faunal turnover has not yet been clarified. Our high-resolution benthic foraminiferal and carbon isotope analyses at the low latitude Pacific Ocean Shatsky Rise have revealed the following record of major faunal transitions: (1) An initial turnover which involved the benthic foraminiferal extinction event (BFE). The BFE, marked by a sharp transition from Pre-extinction fauna to Disaster fauna represented by small-sized Bolivina gracilis, expresses the onset of the PETM and the abrupt extinction of about 30% of taxa. This faunal transition lasted about 45-74 kyr after the initiation of the PETM and was followed by: (2) the appearance of Opportunistic fauna represented by Quadrimorphina profunda, which existed for about 74-91 kyr after the initiation of the PETM. These two faunas, which appeared after the extinction event, are characterized by low diversity and dwarfism, possibly due to lowered oxygen condition and decreased surface productivity. The second pronounced turnover involved the gradual recovery from Opportunistic Fauna to the establishment of Recovery fauna, which coincided with the recovery about 83-91 kyr after its initiation.

Planktic foraminiferal flux and faunal composition of sediment trap L1_K276 in the northeastern Atlantic

Planktic foraminiferal (PF) flux and faunal composition from three sediment trap time series of 2002-2004 in the northeastern Atlantic show pronounced year-to-year variations despite similar sea surface temperature (SST). The averaged fauna of the in 2002/2003 is dominated by the species Globigerinita glutinata, whereas in 2003/2004 the averaged fauna is dominated by Globigerinoides ruber. We show that PF species respond primarily to productivity, triggered by the seasonal dynamics of vertical stratification of the upper water column. Multivariate statistical analysis reveals three distinct species groups, linked to bulk particle flux, to chlorophyll concentrations and to summer/fall oligotrophy with high SST and stratification. We speculate that the distinct nutrition strategies of strictly asymbiontic, facultatively symbiontic, and symbiontic species may play a key role in explaining their abundances and temporal succession. Advection of water masses within the Azores Current and species expatriation result in a highly diverse PF assemblage. The Azores Frontal Zone may have influenced the trap site in 2002, indicated by subsurface water cooling, by highest PF flux and high flux of the deep-dwelling species Globorotalia scitula. Similarity analyses with core top samples from the global ocean including 746 sites from the Atlantic suggest that the trap faunas have only poor analogs in the surface sediments. These differences have to be taken into account when estimating past oceanic properties from sediment PF data in the eastern subtropical North Atlantic.

Diversity of benthic foraminiferal faunas in Tertiary and Quaternary sediments of DSDP Hole 33-317_Site from the Manihiki Plateau, Pacific Ocean (Table 1)

A study is made of the benthic foraminifers (size fraction > 63 µm) recovered from 59 upper Eocene through Quaternary sediment samples at DSDP Site 317 (Leg 33), located at a depth of 2598 m in the central part of the Manihiki Plateau (South Pacific). The sediments cored are disturbed in only two samples. The stratigraphic assignements used are based on previous studies of planktic foraminifers and other microfossils. In total, 216 taxa are identified. A cluster analysis based on the 77 species which comprised 5% or more of the entire foraminiferal assemblage in at least one sample suggests the presence of 3 major biostratigraphic zones corresponding approximately to the following ages, zone A: middle Miocene-Quaternary; zones B-C: early Miocene-Oligocene; and zone D: Eocene. The most important faunal turnover occurred between the Eocene and the Oligocene; a less pronounced break took place between the early and the middle Miocene, and an additional minor turnover between the Oligocene and the early Miocene. Eighteen taxa are long-ranging, being recorded from the middle Eocene through the Pliocene-Quaternary. It is concluded that, in general, benthic foraminifers of the bathyal zone are poor worldwide stratigraphic guide fossils; the following taxa are conditionally considered as the most suitable in the Eocene-Quaternary sequence: Aragonia aragonensis, Quadrimorphina profunda, Nuttallides truempyi, Abyssamina poagi, Buliminella grata, Bulimina jarvisi, B. macilenta, Turrilina alsatica, Cibicides notocenicus, C. wuellerstorfi, Pyrgo murrhina. However, most of these species are relatively rare.

The rise of modern mammalian faunas: tempo and mode of faunal turnover in western Montana during the Oligocene

Thesis (Ph.D.)--University of Washington, 2016-06