Andrew P. DeVogelaere

Endemicity, Biogeography, Composition, and Community Structure On a Northeast Pacific Seamount

The deep ocean greater than 1 km covers the majority of the earths surface. Interspersed on the abyssal plains and continental slope are an estimated 14000 seamounts, topographic features extending 1000 m off the seafloor. A variety of hypotheses are posited that suggest the ecological, evolutionary, and oceanographic processes on seamounts differ from those governing the surrounding deep sea. The most prominent and oldest of these hypotheses, the seamount endemicity hypothesis (SMEH), states that seamounts possess a set of isolating mechanisms that produce highly endemic faunas. Here, we constructed a faunal inventory for Davidson Seamount, the first bathymetric feature to be characterized as a ‘seamount’, residing 120 km off the central California coast in approximately 3600 m of water (Fig 1). We find little support for the SMEH among megafauna of a Northeast Pacific seamount; instead, finding an assemblage of species that also occurs on adjacent continental margins. A large percentage of these species are also cosmopolitan with ranges extending over much of the Pacific Ocean Basin. Despite the similarity in composition between the seamount and non-seamount communities, we provide preliminary evidence that seamount communities may be structured differently and potentially serve as source of larvae for suboptimal, non-seamount habitats.

Investigations of age and growth for three deep-sea corals from the Davidson Seamount off central California

A recent biological characterization of the Davidson Seamount off central California using a remotely operated vehicle revealed communities rich with deep-sea corals. During this characterization several corals were collected and three colonies were made available for an age and growth study. The colonies examined were identified as bubblegum coral (Paragorgia sp.), bamboo coral (Keratoisis sp.), and precious coral (Corallium sp.). Age was estimated from growth zone counts made in skeletal cross sections. These age estimates were used to estimate growth rates and colony age. Estimated growth rates determined for each species were quite different. The bubblegum coral had a relatively high estimated growth rate, with the precious and bamboo coral estimated as slow growing. These age and growth observations were evaluated relative to published studies on related species and an attempt was made to validate the age and growth estimates with an independent radiometric ageing technique (i.e., lead-210 dating). This approach was not successful for the bubblegum coral, and was successful for the bamboo and precious corals to differing degrees. For the bamboo coral, a minimum colony age of over 200 years was determined. For the precious coral, a linear growth rate of approximately 0.25 cm/yr led to a colony age of about 115 years; however, based on the radial growth rate, an age of up to 200 year is possible.

Deep-sea faunal communities associated with a lost intermodal shipping container in the Monterey Bay National Marine Sanctuary, CA

Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281 m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the containers exterior and the seabed within 10 m of the container differed significantly from those up to 500 m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10 m.

Deep-sea corals and resource protection at the Davidson Seamount, California, U.S.A.

The Davidson Seamount is located 120 km to the southwest of Monterey, along the California coast, USA. It is 2,400 m tall; yet, it is still 1,250 m below the sea surface. In May 2002, 90 hours of digital video was recorded from all depths of the Davidson Seamount, using a remotely operated vehicle, and deep-sea coral specimens were collected. Preliminary analyses indicate that 20 coral taxa were found, and they were almost exclusively located in high relief, ridge areas. Other species were noted on or adjacent to the corals. Because of its pristine nature, as well as human threats and great potential for education, the Davidson Seamount is under consideration for protection as part of the Monterey Bay National Marine Sanctuary.

Temporal variations in humpback whale (Megaptera novaeangliae) song in Monterey Bay National Marine Sanctuary, northeast Pacific

Using two years of nearly continuous recordings from Monterey Bay National Marine Sanctuary, August 2015 through July 2017, variations in humpback whale song are examined on diel, seasonal, and interannual time scales. The cabled hydrophone is in humpback feeding and migratory habitat at 36.7128°N, 122.186°W. Diel analyses show 69% of song during night, 23% during day, and 8% during dusk or dawn. Seasonal analyses show song absence during summer (June–August), emergence during fall (September–October), peak during late fall/winter (November–January), and highly variable detection during spring (February–May). During both years >80% of song occurred during the November–January peak. Song detection within a month reached a maximum of 58% of the time during November 2016. Song length increased (p < 0.01) month-to-month from the start in fall through the end of the peak in January. The months of maximum song occurrence coincide with declining visual sighting of humpbacks within Monterey Bay, consistent with s...