Seasonality in fish larval assemblage structure within marine reef National Parks in coastal Kenya

Abstract

Variability of larval assemblages within marine habitats has an effect on population structure of adults, and on patchiness of populations in space and time. However, despite this effect, few studies have examined this variability in the Western Indian Ocean (WIO) especially in relation to marine park boundaries. In this study, we tested the hypothesis that seasonality and biophysical variables influence fish larval assemblage structure within two of the oldest marine parks in Kenya of differing reef structure. Monthly samples were obtained from the parks using oblique plankton tows for 14-24 months. A total of 38 families and 52 genera of fish larvae were obtained from Malindi Marine Park, while 20 genera in 20 families were sampled from the more enclosed Watamu Marine Park but with a connection to an estuarine system. The preflexion larvae comprised over 80% of the total larvae in the parks with the dominant groups being; Gobiidae, Blenniidae, Engraulidae and Apogonidae. The availability of a wide size range of larvae for some groups like Blenniidae, Gobiidae, Engraulidae, Labridae and Scaridae indicated the possibility of some larvae completing their pelagic phase within the parks. Larval densities differed significantly between seasons and stations in both parks, with higher densities ranging between 95-311 larvae/100 m 3 during the calm northeast monsoon (NEM) season, compared to 5-58 larvae/ 100 m 3 during the stormy southeast monsoon (SEM) season. Stepwise multiple regression analysis indicated a significant positive influence of zooplankton density on fish larval abundance in Malindi Park, while a positive and significant influence of temperature was found in Watamu Park. Distinct assemblages of larvae occurred within the parks indicating within park patchiness in larval distribution and, perhaps existence of retention features. These results provide useful baseline data on larval distribution in the WIO, and will be useful in understanding population dynamics of adult populations when complimented with additional oceanographic data.

Composition and structure of the mangrove fish and crustacean communities of Vanga Bay, Kenya

“…to vary with monsoon seasons (Lugendo et al, 2005;Crona and Rönnbäck, 2007). While juvenile fishes occupying mangrove habitats have been found to be more abundant in SEM than in NEM, in the current and previous work (Crona and Rönnbäck, 2007), densities of planktonic fish larval assemblages in marine parks in Kenya were higher in NEM when waters were calm compared to the rougher SEM season (Mwaluma et al, 2011). McClanahan (1988…”

Role of circulation scales and water mass distributions on larval fish habitats in the Eastern Tropical Pacific off Mexico

“…Mesoscale structures like fronts and eddies can trap and concentrate fish eggs and fish [Nakata et al, 2000;Bakun, 2006;Contreras-Catala et al, 2012;S anchez-Velasco et al, 2014]. Seasonality causes changes in larval composition and abundance of species that inhabit any given region [Espinosa-Fuentes and Flores-Coto, 2004;S anchez-Velasco et al, 2009;Auth et al, 2011;Mwaluma et al, 2011]. The effects of interannual variability like El Niño could modify the fish larvae community structure by means of significant environmental changes, such as temperature increase, pycnocline deepening, and decrease of primary production [Kamburska and Fonda-Umani, 2009;Lavaniegos et al, 2009;Auth et al, 2011].…”

Exploring the larval fish community of the central Red Sea with an integrated morphological and molecular approach

“…In contrast to the Red Sea, the exploration of the distribution and structure of the early-stage larval fish assemblages in other major tropical coral reef-associated habitats was initiated several decades ago [ 10 – 12 ]. Research efforts have been largely focused in Australian waters and the Pacific [ 11 , 13 , 14 ], the Caribbean [ 15 , 16 ], the Mesoamerican Barrier Reef [ 17 – 20 ], and in other ecosystems [ 54 , 55 ]. The majority of these studies have addressed the mesoscale horizontal and/or vertical changes of larval fish communities with changing proximity from coral reefs, while their seasonal variation has been less studied [ 18 , 54 – 57 ].…”

“…Research efforts have been largely focused in Australian waters and the Pacific [ 11 , 13 , 14 ], the Caribbean [ 15 , 16 ], the Mesoamerican Barrier Reef [ 17 – 20 ], and in other ecosystems [ 54 , 55 ]. The majority of these studies have addressed the mesoscale horizontal and/or vertical changes of larval fish communities with changing proximity from coral reefs, while their seasonal variation has been less studied [ 18 , 54 – 57 ]. Although the efficiency of molecular taxonomy for larval fish from coral reefs has been tested [ 32 , 33 , 58 ], the ecological characterization of larval fish assemblages so far has been mostly restricted to the family level, with only limited utilization of sequencing techniques [ 20 ].…”

“…Water temperature appeared to be the main driver of the temporal changes in the structure of the larval fish community in our study, with higher temperatures (after June) signaling the numerical increase of larvae belonging to many families, particularly Scaridae and Labridae, although species-specific variations within a family were also detected (e.g., Scarus niger was only present in winter). Seasonality in assemblage structure (e.g., winter vs. summer) of larval fishes has been detected in several studies in other tropical areas where ichthyoplankton was sampled on a monthly [ 18 , 54 , 55 ] or less frequent basis [ 56 , 57 ] for one or two-year periods. No previous information on larval fish abundance and diversity is available for the Red Sea.…”