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Title: Disentangling the effects of fishing and environmental forcing on demographic variation in an exploited species
Description: Species targeted by fishing often recover in abundance and size within marine protected areas (MPAs) resulting in increased reproductive potential. However, in some situations, concomitant changes in the abundance of predators, competitors, or prey within MPAs, or strong gradients in the surrounding environmental seascape may counteract the purported benefits making it more difficult to predict how species will respond to protection. We used a network of MPAs in California, spanning a large temperature gradient, to investigate the drivers of demographic variability in the commercially important red sea urchin Mesocentrotus franciscanus. We investigated how demographic metrics varied geographically in response to protection, temperature, and the main sea urchin resource, the giant kelp Macrocystis pyrifera. We found significant conservation benefits to this fished sea urchin within MPAs designated six years prior to the beginning of this study. Within MPAs, red sea urchins were generally larger resulting in greater adult biomass density and reproductive biomass density. In addition, kelp density was an important explanatory variable of all red sea urchin demographic traits examined (adult size, gonadosomatic index [GSI], density, adult biomass density, and reproductive biomass density). Kelp density was positively correlated with red sea urchin GSI and adult size, but the relationships with density, adult biomass density, and reproductive biomass density were complex and the directionality changed depending on the region (or environmental setting) examined. Our results demonstrate that kelp, red sea urchin reproduction, and the effects of spatial management on demographic processes are tightly coupled with the oceanographic regime. © 2017 Elsevier Ltd
Author: Teck, Lorda, Shears, Bell, Cornejo-Donoso, Caselle, Hamilton, Gaines

Title: Natural History Observations of Hawaiian Garden Eels, Gorgasia hawaiiensis (Congridae: Heterocongrinae), from the Island of Hawai'i, Natural History Observations of Hawaiian Garden Eels
Description: Garden eels occur worldwide in the tropics, but little is known about their biology and ecology. We studied Hawaiian garden eel (Gorgasia hawaiiensis) colonies near Kawaihae, Hawai'i, to investigate multiple aspects of basic biology of this species. Colonies of G. hawaiiensis occurred at depths from 16 to 36 m in soft-bottom habitat adjacent to rocky reefs. Highest burrow densities (up to 40 eels m-2) were in shallower water, and large (~10 mm diameter) burrows were more abundant, less dense, and commonly found in pairs in deeper water. Eels emerged around sunrise and withdrew and covered burrow entrances around sunset. Age was estimated from annual rings in sectioned otoliths (n = 17) and modeled to suggest fast growth to a maximum size of ~600 mm total length and a maximum age of 6 yr. Prey size and eel anatomy suggest that these fish feed by ingesting planktonic prey and processing them in the esophagus. The most common food items were small (<0.5 mm) demersal harpacticoid, cyclopoid, and calanoid copepods and unidentified fish eggs. These and other observations indicate that G. hawaiiensis is abundant, has a high population turnover rate, and may enrich sandy-bottom habitat within their beds by facilitating energy flow from the water column to the benthos. © 2017 by University of Hawai'i Press., Export Date: 17 April 2017, Article
Author: Donham, Foster, Rice, Cailliet, Yoklavich, Hamilton

Title: First quantification of subtidal community structure at Tristan da Cunha Islands in the remote South Atlantic from kelp forests to the deep sea
Description: Tristan da Cunha Islands, an archipelago of four rocky volcanic islands situated in the South Atlantic Ocean and part of the United Kingdom Overseas Territories (UKOTs), present a rare example of a relatively unimpacted temperate marine ecosystem. We conducted the first quantitative surveys of nearshore kelp forests, offshore pelagic waters and deep sea habitats. Kelp forests had very low biodiversity and species richness, but high biomass and abundance of those species present. Spatial variation in assemblage structure for both nearshore fish and invertebrates/algae was greatest between the three northern islands and the southern island of Gough, where sea temperatures were on average 3-4o colder. Despite a lobster fishery that provides the bulk of the income to the Tristan islands, lobster abundance and biomass are comparable to or greater than many Marine Protected Areas in other parts of the world. Pelagic camera surveys documented a rich biodiversity offshore, including large numbers of juvenile blue sharks, Prionace glauca. Species richness and abundance in the deep sea is positively related to hard rocky substrate and biogenic habitats such as sea pens, crinoids, whip corals, and gorgonians were present at 40% of the deep camera deployments. We observed distinct differences in the deep fish community above and below ~750 m depth. Concurrent oceanographic sampling showed a discontinuity in temperature and salinity at this depth. While currently healthy, Tristan's marine ecosystem is not without potential threats: shipping traffic leading to wrecks and species introductions, pressure to increase fishing effort beyond sustainable levels and the impacts of climate change all could potentially increase in the coming years. The United Kingdom has committed to protection of marine environments across the UKOTs, including Tristan da Cunha and these results can be used to inform future management decisions as well as provide a baseline against which future monitoring can be based.
Author: Caselle, Hamilton, Davis, Thompson, Turchik, Jenkinson, Simpson, Sala

Title: Recovery trajectories of kelp forest animals are rapid yet spatially variable across a network of temperate marine protected areas
Description: Oceans currently face a variety of threats, requiring ecosystem-based approaches to management such as networks of marine protected areas (MPAs). We evaluated changes in fish biomass on temperate rocky reefs over the decade following implementation of a network of MPAs in the northern Channel Islands, California. We found that the biomass of targeted (i.e. fished) species has increased consistently inside all MPAs in the network, with an effect of geography on the strength of the response. More interesting, biomass of targeted fish species also increased outside MPAs, although only 27% as rapidly as in the protected areas, indicating that redistribution of fishing effort has not severely affected unprotected populations. Whether the increase outside of MPAs is due to changes in fishing pressure, fisheries management actions, adult spillover, favorable environmental conditions, or a combination of all four remains unknown. We evaluated methods of controlling for biogeographic or environmental variation across networks of protected areas and found similar performance of models incorporating empirical sea surface temperature versus a simple geographic blocking term based on assemblage structure. The patterns observed are promising indicators of the success of this network, but more work is needed to understand how ecological and physical contexts affect MPA performance. © 2015, Nature Publishing Group. All rights reserved., Export Date: 2 October 2015
Author: Caselle, Rassweiler, Hamilton, Warner
Date: 2015-01-01T00:00:00Z

Title: Historical ecology and the conservation of large, hermaphroditic fishes in Pacific Coast kelp forest ecosystems
Description: The intensive commercial exploitation of California sheephead (Semicossyphus pulcher) has become a complex, multimillion-dollar industry. The fishery is of concern because of high harvest levels and potential indirect impacts of sheephead removals on the structure and function of kelp forest ecosystems. California sheephead are protogynous hermaphrodites that, as predators of sea urchins and other invertebrates, are critical components of kelp forest ecosystems in the northeast Pacific. Overfishing can trigger trophic cascades and widespread ecological dysfunction when other urchin predators are also lost from the system. Little is known about the ecology and abundance of sheephead before commercial exploitation. Lack of a historical perspective creates a gap for evaluating fisheries management measures and marine reserves that seek to rebuild sheephead populations to historical baseline conditions. We use population abundance and size structure data from the zooarchaeological record, in concert with isotopic data, to evaluate the long-term health and viability of sheephead fisheries in southern California. Our results indicate that the importance of sheephead to the diet of native Chumash people varied spatially across the Channel Islands, reflecting modern biogeographic patterns. Comparing ancient (~10,000 calibrated years before the present to 1825 CE) and modern samples, we observed variability and significant declines in the relative abundance of sheephead, reductions in size frequency distributions, and shifts in the dietary niche between ancient and modern collections. These results highlight how size-selective fishing can alter the ecological role of key predators and how zooarchaeological data can inform fisheries management by establishing historical baselines that aid future conservation.
Author: Braje, Rick, Szpak, Newsome, McCain, Elliott Smith, Glassow, Hamilton

Title: From a sea of phenotypic traits, fast reaction and boldness emerge as the most influential to survival in marine fish
Description: Predation is arguably the most consequential of ecological interactions in determining fitness and thus natural selection; prey that do not escape a predator encounter become dinner and can no longer pass their genes on to the next generation. For organisms with complex life histories (e.g. plants, insects, amphibians, marine fish, invertebrates and algae; Wilbur, 1980), processes occurring during transitions between life stages are particularly important for subsequent survival and reproduction (e.g. Berven, 1990; Johnson, Grorud‐Colvert, Sponaugle, & Semmens, 2014; Pechenik, 2006). Mortality is intense at these vulnerable developmental stages (Almany & Webster, 2006; Hjort, 1914), especially when those life‐history transitions involve a habitat shift (i.e. pelagic larva to benthic‐associated juvenile for marine species) where individuals are naïve about new predators and other risks. In marine systems, early results showed that bigger, faster growing, or better‐conditioned individuals were more likely to survive the larval‐juvenile transition (Hamilton, Regetz, & Warner, 2008; Hoey & McCormick, 2004; Searcy & Sponaugle, 2001; Vigliola & Meekan, 2002). Understanding which individuals survive periods of selective mortality, from birth to reproduction, remains fundamental to our understanding of both demographic and evolutionary processes.
Author: Hamilton

Title: Ecosystem assessment of the Tristan Da Cunha Islands
Description: In January–February 2017, National Geographic’s Pristine Seas project, in collaboration with the Royal Society for the Protection of Birds (RSPB) and the Tristan da Cunha Government (including the Fisheries and Conservation Departments) conducted a 21-day expedition to Tristan da Cunha, Nightingale, Inaccessible and Gough Islands. The primary goals of the expedition were to conduct comprehensive quantitative surveys of the health of the archipelago’s largely unknown marine environment to assist the Government and people of Tristan da Cunha in planning marine protection . The results of the expedition highlight the unique marine ecosystem of this archipelago, particularly the pelagic and deep-sea environments, which were virtually unstudied and documented scientifically.The work presented in this report is meant to complement ongoing research at Tristan da Cunha and provide a springboard to help inform the Tristan Government about potential protection schemes that protect both important fisheries and unique biodiversity of the archipelago. .
Author: Caselle, Hamilton, Davis, Bester, Wege, Thompson, Turchik, Jenkinson, Simpson, Mayorga