http://www.esf.edu/efb/mitchell/Myron%20Ref/Park%20et%20al%202010_Env%20Int.pdf

Potential effects of climate change and variability on watershed biogeochemical processes and water quality in Northeast Asia.

Dolphins live in complex social groupings with a wide variety of social strategies. In this chapter we investigate the role that differing habitats and ecological conditions have played in the evolution of delphinid social strategies. We propose a conceptual framework for understanding natural patterns of delphinid social structure in which the spatial and temporal predictability of resources influences the ranging patterns of individuals and communities. The framework predicts that when resources are spatially and temporally predictable, dolphins should remain resident in relatively small areas. Predictable resources are often found in complex inshore environments where dolphins may hide from predators or avoid areas with high predator density. Additionally, available food resources may limit group size. Thus, we predict that there are few benefits to forming large groups and potentially many benefits to being solitary or in small groups. Males may be able to sequester solitary females, controlling mating opportunities. Observations of inshore populations of bottlenose dolphins (Tursiops sp.) and island-associated spinner dolphins (Stenella longirostris) seem to fit this pattern well, along with forest-dwelling African antelope and primates such as vervets (Cercopithicus aethiops), baboons (Papio sp.), macaques (Macaca sp.) and chimpanzees (Pan troglodytes). In contrast, the framework predicts that when resources such as food are unpredictable, individuals must range further to find the necessary resources. Forming groups may be the only strategy available to avoid predation, especially in the open ocean. Larger home ranges are likely to support a greater number of individuals; however, prey is often sparsely distributed, which may act to reduce foraging competition. Cooperative foraging and herding of prey schools may be advantageous, potentially facilitating the formation of long-term bonds. Alternately, individuals may display many short-term affiliations. These large groups make it difficult for a male or a small group of males to sequester a female, and polygynandry is the most likely mating strategy. While it is difficult to study wide-ranging delphinids to examine these predictions, this ranging and behavioural pattern has been suggested for dusky dolphins (Lagenorhynchus obscurus), coastal bottlenose dolphins (Tursiops sp.) and mixed species of dolphins in the Eastern Tropical Pacific. These patterns also resemble the ranging and social strategies of open savannah African antelopes and desert-dwelling macropods. Resource availability exists in a range of complex distributions and we predict that delphinid ranging patterns will also vary. At intermediate-ranging patterns, the framework predicts that individuals should form mid-sized groups balancing intra-group competition with predation protection. Humpback dolphins (Sousa sp.) appear to fit this pattern, with some site fidelity over relatively large ranges. They display fluid associations with other individuals. Predation pressure is not sufficiently high to cause large groups to form, and individuals probably reduce predation pressure more by hiding whenever possible. This pattern is likely to prevent the formation of long-term complex bonds. In contrast, killer whales (Orcinus orca) also display intermediate-ranging patterns, but have extremely strong social bonds within familial groups. Cooperative and altruistic behaviour in killer whales facilitate the formation of life-long bonds, similar to those observations in sperm whales (Physeter macrocephalus) and elephants (Loxodonta africana). This conceptual framework remains largely untested, and for many species it is not currently possible to describe ranging behaviours, anti-predator tactics or social behaviour in sufficient detail for appropriate examination of these ideas. Few studies on dolphins have been conducted to explicitly test this type of framework; however, existing observations of delphinid social strategies and communities are used throughout this chapter to examine this framework. Additionally, we anticipate that the present framework may provide a starting point to test hypotheses regarding the evolution of social strategies of delphinids.

The Social Structure and Strategies of Delphinids: Predictions Based on an Ecological Framework

Interannual variability of the physical environment in the eastern tropical Pacific Ocean (ETP) and biological effects of this variability are reviewed and compared to variability in the north- eastern Pacific. El Nino Southern Oscillation (ENSO) scale variability of 2 to 7 yr periods is dominant in the eastern equatorial Pacific and decadal scale variability of 10 to 30 yr periods is dominant in the northeastern Pacific. In the eastern Pacific warm pool at the center of the ETP, temporal variability at any scale is relatively low. ENSO warm (El Nino) and cold (La Nina) events have had a variety of effects on marine populations and ecosystems, but these effects are generally followed by recovery within a few years. El Nino effects such as mortality or reproductive failure are most severe on pop- ulations dependent on local feeding or breeding grounds in coastal waters or around islands. Decadal variability has also caused change in populations and ecosystems. Most of these effects have been observed in the California Current, Gulf of Alaska, and other well studied regions of the Pacific. The 1976-1977 phase change or 'regime shift' is the most well known case of decadal variability. It affected the physical environment throughout the Pacific Ocean and had major effects on North Pacific ecosystems. No regime shift has been detected in the ETP since 1977. However, ENSO vari- ability continues, an unusually persistent warming prevailed in the early 1990s and the thermocline has shoaled in the ETP warm pool area since 1980. Potential population effects on dolphin stocks are discussed. Interaction of environmental changes with other factors, such as fishery stress or mortality, may also induce population effects.

/pdf/environmental-change-in-the-eastern-tropical-pacific-ocean-qdo7vtul4e.pdf

Environmental change in the eastern tropical Pacific Ocean: review of ENSO and decadal variability

Surveys to assess cetacean presence were conducted in July 1995 and 1997 in the Gulf of Corinth, which is an almost-enclosed sea in Greece, Eastern Mediterranean. The dolphin sighting frequencies were high (0.043 sightings/km). Four dolphin species were encountered: striped dolphins (Stenella coeruleoalba), short-beaked common dolphins (Delphinus delphis), Risso’s dolphins (Grampus griseus) and bottlenose dolphins (Tursiops truncatus). Bottlenose dolphins were encountered only once. Thirteen dolphin sightings were single-species (striped dolphins) and seven were mixed-species with either two species (striped and common dolphins in five sightings), or three species (striped, common, and Risso’s dolphins in two sightings) in the group. In all mixed-species sightings, Risso’s dolphins and common dolphins were always and by far the minority species present. To date, no singlespecies groups of Risso’s or short-beaked common dolphins have been observed in the Gulf of Corinth. Interspecific rake marks on the Risso’s dolphins, and behaviours observed through video analysis, indicate potentially complex and regular interspecific interactions. Our results support the idea that interspecific interactions between sympatric cetacean species in the area are common, and apparently complex.

/pdf/mixed-species-associations-of-striped-dolphins-stenella-4ql72hwqgw.pdf

Mixed-species associations of striped dolphins (Stenella coeruleoalba), short-beaked common dolphins (Delphinus delphis), and Risso's dolphins (Grampus griseus) in the Gulf of Corinth (Greece, Mediterranean Sea)

The combustion of fossil fuels and the resultant impacts on climate may now represent one of the largest environmental threats. In the Mediterranean Sea, changes in bio-chemical and physical seawater properties resulting from global warming are likely to alter marine biodiversity and productivity, trigger trophic web mismatches and encourage diseases, toxic algal bloom and propagation of thermophilic species. This review highlights the current and potential threats of climate change to the Mediterranean marine ecosystems, including cetaceans, and stresses the emergent necessity for more integrated regulations and policies for the protection of marine biodiversity. For instance, in the Mediterranean Sea, the distribution and abundance of the small euphausid species Meganyctiphanes norvegica is correlated with specific hydrobiological parameters including seawater temperature, salinity and current patterns. Situated at the northern limit of its ecological tolerance, this species, which constitutes the only known food supply of the fin whales (Balaenoptera physalus) in this region, might be affected by climate change-induced alteration of ocean circulation.

/pdf/potential-impacts-of-climate-change-and-greenhouse-gas-ngdg523y9s.pdf

Potential impacts of climate change and greenhouse gas emissions on Mediterranean marine ecosystems and cetaceans.

Abundance of pilot whales at Santa Catalina lsland, California, USA, declined from several hundred to between 0 and 33 per winter following the 1982-83 El Nixio-Southern Oscillation. Starting in 1987, abundance of Risso's dolphins, rarely seen before that time, increased. During a 9-winter-long study at Santa Catalina Island, parallels between the behavior and distribution of these 2 medium-sized, squid-eating delphinids were documented. One possibly aggressive encounter between pilot whales and Risso's dolphins was observed and others were reported. These factors led to the hypothesis that, while the ranges of these 2 species overlap, competitive displacement will generally prevent CO-occurrence of these species in restricted geographic areas with limited food resources such as seen at Santa Catalina lsland.

/pdf/relationship-between-pilot-whales-and-risso-s-dolphins-at-11doohnc6x.pdf

Relationship between pilot whales and Risso's dolphins at Santa Catalina Island, California, USA

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Relationship between pilot whales and Risso's dolphins at Santa Catalina Island, California, USA